Project Report On WiFi Based Embedded System Development For Wireless Multimedia Campus Network

By Aparna Anand(200412024) Arunabh Mishra(200412026) Atul Dwivedy(200412031) Esha Goel(200412051) Niharika (200412084) Tanzoom Akhtar(200412131) Umang Chittlangia(200412134) In partial fulfillment of requirements for the award of degree in Bachelor of Technology in Electronics and communication Engineering

(2007-08)

Under the Project Guidance of Dr. (Prof.) R. N. Bera HOD, Department of Electronics and Communication Engineering

35

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY MAJITAR, RANGPO, EAST SIKKIM – 737132

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY (A constitute institute of SMU - Deemed University)

MAJITAR – 737 132, SIKKIM, INDIA JUNE – 2008

Wi-fi MESH NETWORK: SURVEY OF EXISTING WIRELESS NETWORK A project report submitted to

SIKKIM MANIPAL UNIVERSITY (SMU - Deemed University) For Partial Fulfillment of the Requirement for the Award of the Degree of

BACHELOR OF TECHNOLOGY in

ELECTRONICS AND COMMUNICATION ENGINEERING by

APARNA ANAND Reg. No. 200412023 Final Year B. Tech 36

ARUNABH MISHRA Reg. No. 200412025 Final Year B. Tech

ATUL DWIVEDY Reg. No. 200412031 Final Year B. Tech

ESHA GOEL Reg. No. 200412051 Final Year B. Tech

NIHARIKA Reg. No. 200412084 Final Year B. Tech

TANZOOM AKHTAR Reg. No. 200412131 Final Year B. Tech

UMANG CHITTLANGIA Reg. No. 200412134 Final Year B. Tech .

Under the Guidance of Dr. (Prof.) R. N. BERA HOD, Department of Electronics and Communication Engineering

37

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY (A constitute institute of SMU - Deemed University)

MAJITAR – 737 132

DEPARTMENT OF ELECRONICS AND COMMUNICATION ENGINEERING

38

CERTIFICATE This is to certify that the project titled ―WiFi Based Embedded System Development For Wireless Multimedia Campus Network” is a bonafied work of

APARNA ANAND

200412023

ARUNBH MISHRA

200412026

ATUL DWIVEDY

200412031

ESHA GOEL

200412051

NIHARIKA

200412084

TANZOOM AKHTAR

200412131

UMANG CHITTLANGIA

200412134

carried out in partial fulfillment of the requirements for awarding the degree of Bachelor of Engineering under Sikkim Manipal University(SMU – Deemed University), Sikkim during the academic year 2007 – 2008.

Dr. (Prof.) R . N. Bera HOD, E & C dept Project Guide

Dr. (Prof.) R .N . Bera HOD E & C department

39

TABLE OF CONTENTS

Page ACKNOWLEDGEMENTS…………………………………………………

i

ABSTRACT …………………………………………………………….

ii

OBJECTIVES……………………………………………………………

iii

TECHNOLOGY TRENDS LIST OF FIGURES ……………………………………………………..

iv

ABBREVIATIONS …………………………………………………….

v

SURVEY OF WMCN IN SMIT AND DESIGN STRATEGY LIST OF FIGURES……………………………………………………..

vi

LIST OF TABLES………………………………………………………

viii

ABBREVIATIONS …………………………………………………….

ix

IEEE 802.11s IMPLEMENTATION OF WIRELESS MULTIMEDIA CAMPUS NETWORK LIST OF FIGURES……………………………………………………..

xii

LIST OF TABLES………………………………………………………

xv

ABBREVIATIONS …………………………………………………….

xvi

APPLICATION DEVELOPMENT FOR WMN LIST OF FIGURES……………………………………………………..

xviii

LIST OF TABLES………………………………………………………

xx

ABBREVIATIONS …………………………………………………….

xxi

40

CHAPTER

1

TECHNOLOGY TRENDS

1.0

Technology trends……………………………………………….1

1.1

Wireless distribution system…………………………………….1

1.1.1

Repeater WDS link……………………………………………...2

1.1.2

Wireless bridge………………………………………………….3

1.1.3

Wireless repeater………………………………………………..5

1.2

WiMAX technology…………………………………………….6

1.2.1

Intel‘s integrated Wi-fi/WiMAX new technology…………….7

1.2.2

Cost effective architecture……………………………………...8

1.2.3

MIMO powered high throughput………………………………8-9

1.2.4

Flexible radio frequency band support………………………...9

1.3

Single radio, Dual radio and Multi radio wireless mesh networks11

1.3.1

Capacity of Wireless Mesh networks………………………….12

1.3.2

Single radio Wireless mesh……………………………………14

1.3.3

Dual radio Wireless mesh……………………………………..16

1.3.4

Multi radio Wireless mesh…………………………………….17

1.3.5

Advantages of multi radio mesh approach……………………19

1.3.6

Examples WiMAX/Wi-fi multi band dual radio………………20

1.3.7

Conclusion…………………………………………………….26

1.4

Motivation……………………………………………………..27

1.4.1

Case 1:AirJaldi, Dharamsala…………………………………..27

1.4.2

Case 2:Nepal wireless project…………………………………28

1.4.3

Case 3:Africa………………………………………………….30

41

1.4.4

Case 4:California……………………………………………...32

SURVEY OF WMCN IN SMIT AND DESIGN STRATEGY

CHAPTER

1

INTRODUCTION

1.1

Building LAN………………………………………………………35

1.1.1

Wired Technology…………………………………………………36

1.1.2

Wireless Technology……………………………………...............38

1.1.3

Wired vs Wireless …..……. ……………………………………...41

1.2

Typical WLAN Installation……. ………………………………..41

CHAPTER

2

Wi-fi

2.1

IEEE 802.11 Architecture…………………………………………45

2.2

IEEE 802.11 Standards…………………………………………....47

2.2.1

IEEE 802.11b………………………………..…………………..... 48

2.2.2

IEEE 802.11a……………………………………………………...50

2.2.3

IEEE 802.11g……………………………………………………..51

2.3

Competing Technologies to IEEE 802.11……………………..52

2.3.1 HiperLAN2…………………………………………………...52 2.3.2 HomeRF…………………………………………………………...53

CHAPTER 3 3.1

CONSIDERATIONS IN CELL DESIGN

Protocols……………………………………………………...55

42

3.1.1 IEEE 802.11b…………………………………………………55 3.1.2 IEEE 802.11a…………………………………………………56 3.1.3 IEEE 802.11g………………………………………………...56 3.2

Making a choice……………………………………………...58

3.3

Site survey…………………………………………………...58

3.3.1 Outdoor site survey………………………………………….58 3.3.2 Indoor site survey……………………………………………58 3.4

Frequency allocation………………………………………...59

3.5

Equipment Selection…………………………………………59

3.5.1 Buy the right AP…………………………………………….59. 3.5.2 Using two antennas for diversity……………………………..59 3.6

Link Budget…………………………………………………..60

3.7

Gains………………………………………………………….60

3.8

Different losses……………………………………………….60

3.9

Considerations in AP deployment……………………………61

3.9.1 From Coverage perspective……………………………………62 3.9.2 From Capacity perspective…………………………………….62

CHAPTER

4

RANGE

4.1

Factors affecting range………………………………………….64

4.2

RF components…………………………………………………65

4.2.1 Antennas……………………………………………………….65

43

4.2.2 Sensitive Receivers…………………………………………….68 4.2.3 Amplifiers……………………………………………………..68 4.3

Single AP(covering large area)…………………………………68

4.4

Extending WLAN range with repeaters………………………..69

4.5

Importance of unobstructed LoS in Wi-fi……………………...70

CHAPTER 5

IMPLEMENTATION OF WMCN IN SMIT

5.1

Typical Deployment process…………………………………...74

5.2

Mode and Network topology…………………………………..75

5.3

Frequency band………………………………………………...77

5.4

Layout planning………………………………………………..78

5.4.1 Coverage planning……………………………………………..78 5.4.2 Capacity planning……………………………………………...78 5.5

Channel assignment……………………………………………81

CHAPTER 6.1

6

SURVEY OF EXISTING WMN IN SMIT

Factors considered during the survey…………………………….82

6.1.1 Fading…………………………………………………………….82 6.2

Software used…………………………………………………….84

6.2.1 NetStumbler v 0.4.0………………………………………………84 6.3

Survey detail………………………………………………………86

44

CHAPTER

7

DESIGN OF WMN IN SMIT

7.1

Introduction of Wireless Mesh network…………………………93

7.2

Characteristics of WMN…………………………………………94

7.3

Critical factors influencing network performance……………….95

7.4

Description of existing WMN……………………………………98

7.5

Problems in existing WMN………………………………………100

CHAPTER 8.1

8

DESIGNING WMN IN SMIT

Factors while designing the layout………………………………..101

8.1.1 Antenna Type……………………………………………………..101 8.1.2 Area to be covered………………………………………………..104 8.1.3 Range of antenna…………………………………………………105 8.1.4 Gain of antenna…………………………………………………..105 8.1.5 Number of antennas………………………………………………105 8.1.6 Interference problems…………………………………………….105 8.1.7 Height of antennas………………………………………………..105 8.1.8 Antenna efficiency………………………………………………106 8.2

Layout……………………………………………………………106

8.3

Conclusion………………………………………………………. 111

CHAPTER

9

CANTENNA

9.1

Introduction…………………………………………………….112

9.2

Interference, Health and Security concerns…………………….115

45

9.3

Simple antenna theory………………………………………….116

9.3.1 Basic concepts………………………………………………….116 9.3.2 Modulation…………………………………………………….117 9.3.3 Why modulation……………………………………………….120 9.4

Working principle……………………………………………..121

9.4.1 Apparatus required…………………………………………….121 9.4.2 Softwares used………………………………………………...122 9.4.3 Construction…………………………………………………..122 9.4.4 Procedure……………………………………………………..129 9.5

Observations…………………………………………………..137

9.6

Safety measures……………………………………………….139

9.7

Advantages…………………………………………………….139

9.8

Disadvantages…………………………………………………140

IEEE 802.11s IMPLEMENTATION OF WIRELESS MULTIMEDIA CAMPUS NETWORK

CHAPTER 1

WIRELESS MESH NETWORK

1.1

Wireless Mesh network……………………………………….146

1.2

Network architecture…………………………………………148

1.2.1 Infrastructure Mode…………………………………………..149 1.2.2 Client Mode…………………………………………………..150

46

1.2.3 Hybrid Mode………………………………………………….151 1.3

Characteristics of WMN………………………………………152

1.4

Application scenario…………………………………………..155

1.4.1 Broadband Home networking………………………………..155 1.4.2 Community and neighbourhood networking………………...156 1.4.3 Enterprise networking……………………………………….158 1.4.4 Metropolitan area networking………………………………159 1.4.5 Transport systems……………………………………………160 1.4.6 Building automation…………………………………………161 1.4.7 Security surveillance system………………………………...162 1.5

Comparison with existing technologies……………………..163

1.5.1 Mesh vs Adhoc networks……………………………………163 1.5.2 Mesh vs Sensor networks……………………………………164 1.5.3 WLAN coverage…………………………………………….164 1.6

Mesh implementation model…………………………………165

1.6.1 Marginal S/N…………………………………………………165 1.6.2

Long bursts of interference due to devices working in same spectrum………………………………………………...165

1.6.3 Short bursts of interference due to concurrent sends from other router………………………………………………166 1.6.4 Multipath interference…………………………………………167

47

CHAPTER 2

HARDWARE REQUIREMENTS

2.1

Horn antennas…………………………………………………..168

2.2

Parabolic antenna……………………………………………….169

2.3

Standard CAT5 LAN cable…………………………………….169

2.4

Wireless Router WRT54G/WRT54GL…………………………173

2.4.1 LINKSYS WRT54GL v 1.1……………………………………176 2.4.2 WRT54GL features…………………………………………….177 2.4.3 LINKSYS WRT54G router…………………………………….179

CHAPTER 3

SOFTWARE REQUIREMENTS

3.1

MS WINDOWS…………………………………………………185

3.2

LINUX-UBUNTU GUTSY RIBBON…………………………..185

3.2.0 Configuring Wi-fi in UBUNTU…………………………………185 3.2.1 TCPDUMP………………………………………………………187 3.2.2 NDISWRAPPER…………………………………………………..188 3.2.3 Wi-fi Radar………………………………………………………...188 3.2.4 Wireless tools………………………………………………………189 3.3

MATLAB and SIMULINK………………………………………..190

3.4

Other softwares used……………………………………………….191

3.4.1 MAD Wi-fi…………………………………………………………191 3.4.2 Netmeeting………………………………………………………… 191 3.4.3 Netstumbler…………………………………………………………193 3.4.4 SKYPE……………………………………………………………...195

48

3.4.5 PRTG Traffic Monitor………………………………………………196 3.4.6 ANGRY IP…………………………………………………………..200

CHAPTER 4 4.1

FIRMWARE

Tomato firmware………………………………………………………202

4.1.1 Supported devices……………………………………………………..203 4.1.2 Licensing………………………………………………………………203 4.1.3 Upgrading the firmware……………………………………………….203 4.1.4 Menus in Tomato………………………………………………………203 4.1.5 Tools……………………………………………………………………206 4.1.6 Network………………………………………………………………..207 4.1.7 Wireless………………………………………………………………..208 4.1.8 Identification…………………………………………………………...210 4.1.9 Time……………………………………………………………………210 4.1.10 DDNS…………………………………………………………………..211 4.1.11 Static DHCP……………………………………………………………212 4.1.12 Wireless Filter………………………………………………………….212 4.1.13 Miscellaneous………………………………………………………….212 4.1.14 Routing…………………………………………………………………213 4.1.15 Port forwarding…………………………………………………………216 4.1.16 Basic……………………………………………………………………216 4.1.17 Triggered……………………………………………………………….217 4.1.18 Universal Plug and Play(UPnP)……………………………………….217

49

4.1.19 QoS…………………………………………………………………….218 4.1.20 Basic settings…………………………………………………………..218 4.1.21 Administration…………………………………………………………220 4.1.22 Reboot…………………………………………………………………222 4.1.23 Shutdown………………………………………………………………222 4.1.24 Logout………………………………………………………………….222 4.1.25 Features………………………………………………………………...227 4.2

FREIFUNK………………………………………………………………228

4.3

OPENWRT………………………………………………………………233

APPLICATION DEVELOPMENT FOR WMN

CHAPTER

1

WIRELESS MESH NETWORKS DEPLOYED IN SMIT

1.1

Introduction……………………………………………………………..240

1.2

Router configuration parameters……………………………………….240

1.2.1 Router ‗A‘………………………………………………………………240 1.2.2 Router ‗B‘………………………………………………………………240 1.2.3 Router ‗C‘………………………………………………………………241 1.2.4 Router ‗D‘……………………………………………………………...241 1.3.

The practical experiment………………………………………………242

CHAPTER 2 2.1

MULTIMEDIA TRANSMISSION

Multimedia transmission……………………………………………….243

50

2.1.1 Point to Point Transmission……………………………………………243 2.1.2 Multimedia Broadcasting………………………………………………246 2.2.

Chat……………………………………………………………………..252

2.2.1 Program for Chat Application…………………………………………..252 2.3

Voice over internet protocol…………………………………………….256

2.3.1 VoIP Challenges…………………………………………………………256 2.4.

Intranet………………………………………………………………….258

2.5.

Internet………………………………………………………………….259

CHAPTER 3 3.1

GRAPHICAL USER INTERFACE

Graphical user interface…………………………………………………260

3.1.1 How Does a GUI Work………………………………………………….261 3.1.2 What Is Callback? .....................................................................................261 3.2

Guide: A brief introduction……………………………………………..261

3.3

Programming the GUI……………………………………………………262

3.4

Laying out a GUI…………………………………………………………262

3.4.1 Opening a New GUI In The Layout Editor………………………………262 3.4.2 The Layout Editor………………………………………………………...265 3.4.3 The Completed Layout…………………………………………………...267 3.5

Saving the GUI layout……………………………………………………268

3.6

Illustration of a simple GUI………………………………………………272

3.6.1 Buttons in the GUI………………………………………………………..273 3.7

The obtained M-code……………………………………………………..279

51

3.8

Some of the frequently used commands………………………………… 285

3.9

What is Profiling…………………………………………………………290

3.10 Opening the Profiler………………………………………………………290 3.11 Running the Profiler………………………………………………………291 3.12 Profiling a GUI……………………………………………………………292 3.13 Profile a summary report………………………………………………….293 3.14 Conclusion…………………………………………………………………293

REFERENCES……………………………………………………………………295

52

ACKNOWLEDGEMENT We take this opportunity to express our deep sense of gratitude to Dr. (Brig.) S.N.Mishra (Director, Sikkim Manipal Institute of Technology) and Dr. Rabindranath Bera (Head, Dept. Of Electronics and Communication Engineering, SMIT), who was also our project guide, for providing us the opportunity to undergo our major project at SMIT college campus. We also like to thank them for providing us with the necessary infrastructure.

We express our heartiest thanks to Mr. Debdutta Kandar (Lecturer, Dept. Of Electronics and Communication Engineering, SMIT), Mr. Arghya Gucchait (Lecturer, Dept. Of Electronics and Communication Engineering, SMIT) and Mr. Shubhankar Shome (Lab. Technician, Dept. Of Electronics and Communication Engineering, SMIT), our internal supervisors for their consistent support and guidance during the entire period of the project.

We also express our thanks to the entire faculty of Dept. Of Electronics and Communication Engineering and SMIT as a whole, for their invaluable guidance, support and encouragement during the working with the project.

We also thank all the people involved with our project. Without their support and encouragement this project could not have been possible.

53

Aparna Anand

(200412024)

Arunabh Mishra

(200412026)

Atul Dwivedy

(200412031)

Esha Goel

(200412051)

Niharika Prasad

(200412084)

Tanzoom Akhtar

(200412131)

Umang Chittlangia

(200412134)

i

ABSTRACT

With the advent of new technologies the various wireless networks have evolved to provide better services. In WMN node are comprised of mesh routers and mesh clients. WMN is dynamically self-organized and self configured. Researches have been going on to establish protocol for mesh networking using current technologies such as IEEE 802.11, IEEE 802.15 and 802.16.

Wireless mesh network (WMN) consists of mesh points and wireless mesh backbone of routers providing services to various heterogeneous users. The WMN is a rapidly evolving technology and is gaining popularity as a alternate solution to Ethernet and other wireless protocols. This paper gives a brief introduction of WMN and the work going on for its successful deployment. It also provides insight into the test beds that have been set up for testing the various parts of a wireless mesh network.

54

ii

OBJECTIVE Wireless mesh networking (WMN) has gain popularity over the last few years. For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. It‘s not only large cities but many rural areas which are setting up wireless mesh networks for contact with the outside world. Provision of internet through wireless networks to such places can really work as a tool for development. When we became interested in this field, we started searching about various pilot projects and other areas of expertise in wireless mesh networking, over the internet. One such pilot project was successfully employed in Dharmshala. This pilot project and one or two others served as an inspiration for us. We contacted Mr. Yahel Den David who was the brain behind the Dharmshala project. This was of great help to us. We started going through various other works done in wireless mesh networking across the globe. Next, we thought of implementing a wireless mesh network in our college. For this purpose we divided our team members in three groups. Survey of existing wireless network in SMIT and design strategy. IEEE 802.11s: Implementation for wireless multimedia campus network. Application development for WMN (wireless mesh network).

Survey of the existing network is necessary for measuring the present status and for developing a design strategy as to complement the existing network with our wireless mesh network. For implementation of WMN, we plan to buy the required routers and antennas. After deploying it in short range communication, we plan to test the network

55

for long range (point to point and point to multipoint). Application development will be worked upon using MATLAB and SIMULINK.

iii

TECHNOLOGY TRENDS LIST OF FIGURES Figure

Title

Page

1.1

Point to Point WDS link………………………………………….1

1.2

Point to Multipoint WDS link……………………………………2

1.3

WDS configurations……………………………………………..2

1.4

Wireless bridge configuration…………………………………...4

1.5

Wireless repeater configuration…………………………………5

1.6

WiMAX blanket…………………………………………………7

1.7

MIMO: Key enabler of WiMAX………………………………...10

1.8

Innovative integrated antenna design……………………………10

1.9

Meshing around obstructions……………………………………13

1.10 Single radio Mesh cluster……………………………………….15 1.11 Dual radio wireless mesh, string of Mesh APs………………….17 1.12 Multi radio wireless mesh, string of mesh APs………………….18 1.13 Point to point link………………………………………………..22 1.14 Point to Multipoint link………………………………………….23 1.15 The Dual Bel-Air radio………………………………………… 24 56

iv

ABBREVIATIONS USED

WDS: Wireless Distribution System LAN: Local Area Network AP: Access Point WAN: Wide Area Network Wi-fi: Wireless Fidelity MIMO: Multiple Input Multiple Output SISO: Single Input Single Output UL: Up Link DL: Down Link Tx: Transmitter Rx: Receiver DSL: Digital Subscriber Line MAC: Medium Access Control QoS: Quality of Service DHCP: Dynamic Host Cnofiguration Protocol WEP: Wireless Encryption Protocol WRMs: WiMAX Radio Modules BRMs: Backhaul Radio Modules ARMs: Access Radio Modules VOIP: Voice Over Internet Protocol VSAT: Very Small Aperture Terminal ICT: Information and Communication Technologies

57

v

SURVEY OF WMCN IN SMIT AND DESIGN STRATEGY LIST OF FIGURES Figure

Title

Page

2.1

Adhoc mode………………………………………………………

45

2.2

Infrastructure mode………………………………………………

46

4.1

Radiated power of antennas………………………………………

66

4.2

Access point to client device communication……………………

67

4.3

Images showing LoS,nLoS,NLoS………………………………..

71

5.1

Typical deployment process……………………………………..

74

5.2

Communication in Mesh topology………………………………

76

5.3

Channel layout for 3 storied building with classrooms…………

81

6.1

Graph obtained from Netstumbler………………………………

85

6.2

Screen obtained from NetStumbler……………………………..

86

6.3

Signal strength distribution across the college campus…………

88

6.4

Graph plotted in excel for signal vs range………………………

90

6.5

Graph plotted in Netstumbler for SNR vs time…………………

91

7.1

Area to be covered………………………………………………

99

8.1

Contour mapping for signal variation…………………………..

107

58

8.2

User interface of software by Hughes………………………….

108

8.3

User interface of software by Hughes………………………….

109

8.4

User interface of software by Hughes…………………………

109

8.5

Screen showing inputs and outputs……………………………

110

9.1

Simple cantenna……………………………………………….

114

vi

59

9.2

Block diagram of a simple wireless system…………………..

117

9.3

A sinusoidal wave………………………………………………

119

9.4-9.10

Steps for making cantenna…………………………………

122-128

9.11

Final cantenna…………………………………………………..

129

9.12

Net stumbler in use……………………………………………..

130

9.13

Cantenna signal detected by laptop…………………………….

131

9.14

Apparatus for the experiment…………………………………..

132

9.15

Signal strength obtained from cantenna………………………..

135

9.16

Signal strength obtained without cantenna……………………..

136

9.17

Double can cantenna……………………………………………

139

9.18

Position of maximum radiation………………………………...

140

vii 60

61

LIST OF TABLES

Table

Title

Page

1.1

Pros and cons of Wired Technology……………………………………….

37

1.2

Pros and cons of Wireless Technology …………………………………

39

1.3

Comparison of Wired and Wireless technology………………………..

41

2.1

Wireless local area Networking technologies …………………………

53

3.1

Frequency bands and associated power limits.…………………………..

57

4.1

Relative attenuation of radio frequency obstacles……………………….

64

4.2

Few obstructions that will decrease the signal……………………………

6.1

Categorization of signal wrt colours ………………………………………

6.2

Readings for signal wrt distance…………………………………………...

7.1

Description of existing antennas…………………………………………..

98

7.2

Description of existing routers…………………………………………….

99

8.1

Colour coding for signal strength variation……………………………..

111

9.1

Readings of original cantenna………………………………………

133

9.2

Readings of double can cantenna…………………………………….

136

9.3

Readings without cantenna……………………………………………

137

62

72 87 89

viii

ABBREVIATIONS USED LAN: Local Area Network MAN: Metropolitan Area Network WLAN: Wireless Local Area Network Wi-fi: Wireless fidelity QoS: Quality of Service AM: Amplitude Modulation FM: Frequency Modulation EM: Electromagnetic EMR: Electromagnetic Radiation IEEE: Institute of Electrical and Electronics Engineering PCs: Personal Computers ISM: Industrial, Scientific and Medical U-NII: Unlicensed National Information Infrastructure BSS: Basic Service Set DS: Distribution System LLC: Logical Link Control layer PSK: Phase Shift Keying QPSK: Quadrature Phase Shift Keying CCK: Complementary Code Keying PBCC: Pocket Binary Convolutional Coding ESS: Extended Service Set DSSS: Direct Sequence Spread Spectrum FHSS: Frequency Hopping Spread Spectrum FCC: Federal Communications Commission OFDM: Orthogonal Frequency Division Multiplexing QAM: Quadrature Amplitude Modulation

63

FFT: Fast Frequency Transform ix

ATM: All Transaction Machine IP: Internet Protocol HomeRF: Home Radio Frequency AP: Access Point SWAP: Shared Wireless Access Protocol EIRP: Effective Isotropic Radiated Power MSS: Mobile Satellite Service RF: Radio Frequency SNR: Signal to Noise Ratio BER: Bit Error Rate ERP: Effective Radiated Power HPA: High Power Amplifier SSID: Service Set Identifier LoS: Line of Sight nLoS: Near Line of Sight NLos: Non Line of Sight Pt: Point WMCN: Wireless Multimedia Campus Network WMN: Wireless Mesh Network PDAs: Personal Desktop Assistant MIMO: Multiple Input Multiple Output MAC:

Medium access control

TDMA: Time Division Multiple Access CDMA: Code Division Multiple Access CSMA/CA: Channel Sensing Multiple Access/Channel TCP: Transmission Control Protocol VHF: Very High Frequency

64

UHF: Ultra High Frequency PCM: Pulse Code Modulation ISPs: Internet service providers x IBSS: Independent Basic service set Dist.: Distance Mbits: Mega bits Kbps: Kilo bits per second MW: Mega Watt mW: Milli Watt km: Kilometer dB: Decibal GHz: Giga Hertz

xi

65

IEEE 802.11s IMPLEMENTATION OF WIRELESS MULTIMEDIA CAMPUS NETWORK

LIST OF FIGURES

Figure

Title

Page

1.1

Wired infrastructure………………………………………………

146

1.2

Wired Mesh infrastructure………………………………………..

147

1.3

Examples of Mesh routers based on different embedded systems (a)Power PC Advance Risc Machine(ARM)……………

148

1.4

Infrastructure /backbone WMNs…………………………………

150

1.5

Client WMN………………………………………………………

151

1.6

Hybrid WMN……………………………………………………..

152

1.7

WMN for broadband home networking…………………………..

156

1.8

WMNs for Community networking……………………………….

157

1.9

WMN for enterprise networking…………………………………..

159

1.10 WMN for metropolitan area network……………………………… 160 1.11 WMN for transport system………………………………………… 161 1.12 WMN for building automation…………………………………….. 162 1.13 Long bursts of interference………………………………………… 165 1.14 Short bursts of interference…………………………………………. 166 1.15 Multipath interference………………………………………………. 167

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2.1

xii Horn antenna…………………………………………………………168

2.2

RJ45 cable…………………………………………………………….169

2.3

RJ45 plug……………………………………………………………..170

2.4

IPOD touch……………………………………………………………171

2.5

IPOD interface…………………………………………………………173

2.6

Linksys WRT54G router……………………………………………….175

2.7

Linksys WRT54G router and related accessories………………………175

2.8

Internal architecture of WRT54GL router………………………………178

2.9

Linksys WRT54GL block diagram……………………………………..179

3.1

Wi-fi Radar………………………………………………………………189

3.2

Netmeeting……………………………………………………………….192

3.3

Netstumbler graph………………………………………………………..193

3.4

A typical Netstumbler window…………………………………………..194

3.5

A SKYPE window……………………………………………………….195

3.6

PRTG traffic monitor…………………………………………………….196

3.7

Table 24 hours-5 minute averages……………………………………….197

3.8

Live graph-60 minutes-10 second interval……………………………….198

3.9

Data……………………………………………………………………….199

3.10 Angry IP scanner………………………………………………………….200 4.1

Tomato Device list………………………………………………………...223

4.2

QoS-Basic setting…………………………………………………………224.

4.3 Status-Overview……………………………………………………………225

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Bandwidth realtime(br0)…………………………………………………..226

4.4 4.5

Bandwidth real time(br0)…………………………………………………227

xiii 4.6 Configuration of a mesh node……………………………………………….229 4.7

Setting up administration setting………………………………………....230

4.8

Setting up FREIFUNK firmware for wireless…………………………....231

4.9

Status – router…………………………………………………………....232

4.10

Setup- Basic setup……………………………………………………..…233

4.11

SET UP-Advance routing………………………………………………234

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xiv

LIST OF TABLES

Table

Title

Page

1.1

Mesh vs Adhoc network……………………………………………..163

1.2

Mesh vs Sensor network……………………………………………..164

1.3

WLAN coverage……………………………………………………...164

2.1

WRT54G Router configuration………………………………………181

2.2

WRT54GL Router configuration……………………………………..184

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xv

ABBREVIATIONS USED

WMN: wireless mesh network ESS: extended service set BSS: Basic Service Set WEP: wired equivalent privacy IEEE: Institute of Electrical and Electronics Engineering Arms: Advanced Risc Machines Wi-fi: Wireless fidelity NLOS: non-line-of-sight WLAN: Wireless Local Area Network DSL: digital subscriber line MAN: Metropolitan Area Network BACnet: building automation and control networks AP: Access Point S/N: signal to noise ratio PCs: Personal Computers CAT5: Category 5 ASIC: Application-specific integrated circuit NICs: network interface cards IP: Internet Protocol TCP/IP: transfer control Protocol 70

HTTP: hypertext transfer Protocol URLS: Uniform Resource Locator HAL: Hardware Abstraction Layer DHCP: direct host configuration Protocol WINS: Windows Internet Name Service MAC: medium access control WDS: Wireless Distribution System xvi

71

GPL: general public license SSID: Service Set Identifier WEP: wireless encryption protocol NTP: Network Time Protocol DNS: Domain Name Server DDNS: dynamic DNS VOIP: voice over internet protocol UPnP: Universal Plug and Play QoS: Quality of Service ACK: Acknowledgment STA: Wireless client station OLSR: Optimized Link State Routing

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xvii

APPLICATION DEVELOPMENT FOR WMN LIST OF FIGURES

Figure 2.1

Title

Page

Multimedia Transmission Via UDP Port Involving both Audio and Video……………………………………………………...243

2.2

Transmitter Model For MBMS For Video Only……………………. 246

2.3

Transmitter Model For MBMS For Both Audio and Video…………248

2.4

Receiver for Multimedia Communication(Video and Audio) with Key For Authentication…………………………………………250

2.5

The VoIP Interface……………………………………………………258

3.1

A simple GUI…………………………………………………………260

3.2

Opening the GUI……………………………………………………...263

3.3

A Blank GUI(Default)………………………………………………..264

3.4

Different GUI Components…………………………………………..265

3.5

Layout Area…………………………………………………………...266

3.6

Pushbutton in A GUI………………………………………………….267

3.7

A Completed GUI Layout……………………………………………..268

3.8

Dialog Box While Saving GUI………………………………………..269

3.9

The Save As Dialog Box………………………………………………269

3.10 Dialog Box To Change Current Working Directory………………….270. 3.11 A Completed Layout…………………………………………………..271 3.12 GUIDE…………………………………………………………………272 3.13 Completed GUI………………………………………………………..273 3.14 The Video File………………………………………………………....274 3.15 The Internet Explorer webpage………………………………………..275

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3.16 The Opened Simulink Model…………………………………………..276 3.17 The Windows Explorer…………………………………………………277 xviii 3.18 The Notepad…………………………………………………………….278 3.19 Windows Netmeeting Application……………………………………...278 3.20 The mpaly GUI………………………………………………………….285 3.21 Window on Running ‗web‘ Command………………………………….286 3.22 Profiler Window…………………………………………………………291 3.23 Profile Summary Report…………………………………………………293

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xix

LIST OF TABLES

Table

Title

Page

The mPlay command line syntax………………………………………..

285

3.2 Description of ‗stat‘ value……………………………………………...

288

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xx

ABBREVIATIONS USED IP: Internet Protocol DHCP: Direct Host Configuration Protocol WAN: Wide Area Network WDS: Wireless Distribution System SSID: Service set identifier MAC: Medium Access Control LOS: Line Of Sight VoIP: Voice Over Internet Protocol UDP: MBMS: SIP: Session Initiation Protocol GUI: Graphical User Interface GUIDE: Graphical User Interface Development Environment

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xxi

CHAPTER 1

TECHNOLOGY TRENDS

1.0 TECHNOLOGY TRENDS With the advent of new technologies the field of telecommunication has improved . a lot. The wired systems are now being converted to wireless ones. But this technology is in developing stage. The problems of better throughput and area coverage still persist

1.1 WIRELESS DISTRIBUTION SYSTEM (WDS): WDS features allow you to build a completely wireless infrastructure because the network equipment no longer has to be connected to a wired LAN. Also, WDS features allow you to create large wireless networks by linking several wireless access points with WDS links. WDS is normally used in large, open areas where pulling wires is cost prohibitive, restricted or physically impossible.

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Fig 1.1: Point to Point WDS Link

Fig 1.2 Point To Multipoint WDS Link

1.1.1 Repeater WDS Link

Figure 1.3: WDS Configurations

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As shown in Figure 1.2.3, WDS can be deployed in several configurations. In this document, we will introduce two basic WDS configurations: a wireless bridge and wireless repeater.

1.1.2 Wireless Bridge: The wireless distribution system shown in Figure 2 is often called a ―wireless bridge‖ configuration, because it allows you to connect two LANs at the link layer. In Figure 2, the access point (AP) behaves as a standard bridge that forwards traffic between WDS links (links that connect to other AP/wireless bridges) and an Ethernet port. As a standard bridge, the access point learns MAC addresses of up to 64 wireless and/or 128 total wired and wireless network devices, which are connected to their respective Ethernet ports to limit the amount of data to be forwarded. Only data destined for stations which are known to reside on the peer Ethernet link, multicast data or data with unknown destinations need to be forwarded to the peer AP via the WDS link.

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Figure 1.4: Wireless Bridge Configuration

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If, for example, an 802.3 Ethernet frame is sent from a wired Station 1 (Sta1) to Sta3 in Figure 2, frame translations are required while the frame forwards through the WDS link between AP1 and AP2. When AP1 receives the 802.3 frame, the frame is translated to a IEEE 802.11 standard four-address format frame before it is sent to a WDS link. In the four address format frame, the MAC address of Sta1, MAC address of AP1, MAC address of AP2 and MAC address of Sta3 are all included in the 802.11 frame header, and the frame data is same as the original Ethernet frame. Based on information in this four-address format frame, AP2 will reconstruct the 802.3 Ethernet frame when the frame is forwarded to LAN2. If a security algorithm is configured on the APs, AP1 (AP2) will encrypt (decrypt) this four-address format frame before frame forwarding. From Sta3‘s point of view, the bridging function is transparent; i.e., the received frame is the same as if Sta1 and Sta3 resided on the same LAN.

Figure 1.5 Wireless Repeater Configuration

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1.1.3 Wireless Repeater:

In Figure 1.2.5, AP2 is used to extend the range of the wireless infrastructure by forwarding traffic between associated wireless stations and another repeater or AP connected to the wired LAN. Note that the local Ethernet traffic is not forwarded in this mode. Traffic between Sta3 and Sta4 is not forwarded across the WDS link, nor is traffic between Sta5 and Sta6. As with a wireless bridge mode, APs operating in wireless repeater mode need to translate frames into different frame formats when forwarding frames between wireless connections and WDS links; the 802.11 three-address frame format is used on wireless links connected to wireless stations, while the 802.3 four-

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address frame format is used on WDS links connected to other access points. Encryption/ decryption algorithms are also invoked if the AP is configured to be secure. The Office Connect Wireless 11a/b/g Access Point can function as a wireless repeater or wireless bridge if WDS links are configured between the connected AP pairs appropriately.

1.2 WiMAX TECHNOLOGY:

WiMAX is the next giant step in wireless network evolution that mobilizes the internet — miles from the nearest Wi-Fi* hotspot. Mobile WiMAX will blanket large areas — wide area networks (WANs), be they metropolitan, suburban or rural —with multimegabit-per-second mobile broadband Internet access. WiMAX will free broadband from location, transforming it into personal mobile broadband that moves with you. Together, WiMAX and Wi-Fi are ideal companions for enabling convenient, affordable mobile broadband Internet services.

Mobile WiMAX is powered by new wireless technology breakthroughs codified in the IEEE 802.16e-2005 standard. They make WiMAX a ―spectrally efficient‖ wireless technology that delivers higher speeds than today's wide area wireless technologies. And WiMAX is built from the ground up for Internet applications and services with its ―all IP‖ architecture.

WiMAX is being adopted and deployed in many countries around the world. For example, two carriers in the U.S., Sprint and Clearwire, will be deploying WiMAX services in 2008, and over 100 carriers are currently trialing Mobile WiMAX2 around the world. Intel® Centrino® processor technology is poised once again to be at the center of

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this wireless broadband revolution with an industry-leading Wi-Fi/WiMAX solution that cost-effectively leverages the synergies of both technologies.

Figure1.6 : WiMAX blanket

1.2.1 Intel’s Integrated Wi-Fi/WiMax New Technology :

Intel is leading the next generation of mobility with an innovative, integrated, and embedded combo Wi-fi/WiMAX module for laptops. The Intel® Wi-fi/WiMAX dualmode module code-named ―Echo-Peak‖ planned for the Intel Montevina laptop platform will deliver compelling benefits for laptop OEMs, WiMAX operators, and mobile users. • Laptop OEMs – Intel‘s platform-level optimizations deliver unprecedented economic advantage for mobile wireless broadband. The Echo Peak Wi-Fi/WiMAX module

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minimizes the incremental cost and design overhead, streamlines certification, improves power management, and saves valuable laptop real estate. • Mobile WiMAX Operators – Intel Centrino processor technology-based laptops enable new business models for mobile WiMAX operators with potentially lower client device subsidies and consistent subscriber activation processes. Combining Wi-Fi for local area network (LAN) with WiMAX for the WAN opens up new service opportunities. • Mobile Users – Echo Peak silicon and platform optimizations enhance battery life, simplify network access management, and maximize performance in a compact form factor for a richer mobile broadband experience. Users can connect to Wi-Fi or WiMAX networks, depending on their location, mobility and quality-of-service requirements.

1.2.2 Cost-Effective Architecture: Intel‘s innovative Echo Peak design achieves breakthrough cost points for WiMAX network access. Embedding Wi-Fi/WiMAX into the mobile platform provides unmatched platform level optimizations for OEMs. Wi-Fi and WiMAX integration on the same MiniCard or Half MiniCard form factor frees up valuable laptop real estate. Shared antenna innovations ease design-in and enable a platform approach to noise mitigation. Streamlined certification dramatically reduces PC OEM testing time and costs.

1.2.3 MIMO-Powered High Throughput: Echo Peak harnesses the range and performance benefits of the latest smart antenna technology called Multiple Input Multiple Output (MIMO). MIMO technology provides significant increases in throughput and range using the same bandwidth and overall transmission power of Single Input Single Output (SISO) communication systems. Wireless MIMO communication exploits environmental phenomena such as multi-path

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propagation to increase data throughput and range, or reduce bit error rates, rather than attempting to eliminate effects of multi-path propagation. MIMO uses multiple antennas at both the base station and subscriber unit to enable data to travel along different independent paths. MIMO technology is incorporated in the IEEE 802.11n specification (Draft-N) and the IEEE 802.16e-2005 standard (WiMAX). MIMO configurations on the Echo Peak module are 1x2 for WiMAX and 3x3 for Wi-fi. 1x2 refers to a 1 Tx (transmit) and 2 Rx (receive) antenna configuration and 3x3 refers to a 3 Tx and 3 Rx configuration. For Wi-fi, a Wi-fi access point connected to a 3x3 Wi-fi MIMO client needs 3 Tx and 3 Rx antennas to take full advantage of the client‘s configuration. For WiMAX, with its asymmetric antenna configuration, the base station is assumed to have 2 TX antennas that transmit to the 2 Rx antennas on Echo Peak, enabling what is referred to as 2x2 downlink (DL) MIMO. On the uplink (UL), 802.16e-2005 supports a feature called ―collaborative MIMO.‖ So although the Echo Peak module has only 1 Tx antenna, the base station to which it connects can have 2 Rx antennas and can receive simultaneous signals from two different clients, enabling what is referred to as 2x2 collaborative MIMO on the UL. With this configuration, Echo Peak clients can support up to 10 Mbps on DL and up to4 Mbps on UL.

1.2.4 Flexible Radio Frequency Band Support:

The radio antennas to support MIMO capabilities are placed in the laptop LCD display lid and shared by both Wi-fi and WiMAX to reduce costs, ease design considerations, and enable a platform approach to noise mitigation. In the half MiniCard Echo Peak form factor, Wi-fi and WiMAX also share an integrated radio component. In contrast, nonintegrated WAN data cards don‘t make use of the integrated lid antennas in the laptop. These cards have their own antenna which may or may not have been validated with the platform. As a result, noise mitigation management is not necessarily optimized at the platform level.

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Figure 1.7 MIMO : key enabler of WiMAX

Figure 1.8 : Innovative integrated antenna design

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WiMAX will leverage a new generation of wireless technologies to mobilize broadband Internet access. Intel® architecture-based laptops with Echo Peak on the Montevina platform will transform wireless mobility for users while delivering compelling benefits for laptop OEMs and wireless service providers. For OEMs, platform-level optimizations for the integrated, dual-mode Wi-fi/WiMAX module deliver economics not seen before for mobile wireless broadband. For mobile WiMAX operators, laptops with Intel Centrino processor technology and integrated Wi-fi/ WiMAX reduce client subsidies and streamline subscriber activation. For mobile users, Echo Peak on the Montevina laptop platform unleashes the power of next-generation mobile computing.

1.3 SINGLE RADIO, DUAL RADIO AND MULTI-RADIO WIRELESS MESH NETWORKS:

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Mesh is a type of network architecture. Originally, Ethernet was a shared bus topology in which every node tapped into a common cable that carried all transmissions from all nodes. In bus networks, any node on the network hears all transmissions from every other node in the network. Most local area networks (LANs) today use a star topology in which every network node is connected to a switch (switches can be interconnected to form larger networks). Mesh networks are different – full physical layer connectivity is not required. As long as a node is connected to at least one other node in a mesh network, it will have full connectivity to the entire network because each mesh node forwards packets to other nodes in the network as required. Mesh protocols automatically determine the best route through the network and can dynamically reconfigure the network if a link becomes unusable.

There are many different types of mesh networks. Mesh networks can be wired or wireless. For wireless networks there are ad-hoc mobile mesh networks and permanent infrastructure mesh networks. There are single radio mesh networks, dual-radio mesh networks and multi-radio mesh networks. All of these approaches have their strengths and weaknesses. They can be targeted at different applications and used to address different stages in the evolution and growth of the network.

1.3.1 Capacity of Wireless Mesh Networks: The first wireless mesh networks were mobile ad hoc networks – with wireless stations moving around and participating in a peer to peer network. Mesh is an attractive approach for wireless networking since wireless nodes may be mobile and it is common for a wireless node to participate in a network without being able to hear all of the other nodes in the network. Mobile peer to peer networks benefit from the sparse connectivity

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requirements of the mesh architecture; and the combination of wireless and mesh can provide a reliable network with a great deal of flexibility.

The popularity of Wi-fi has generated a lot of interest in developing wireless networks that support Wi-fi access across very large areas. Large coverage access points (AP) are available for these scenarios, but the cost of deploying these wide area Wi-fi systems is dominated by the cost of the network required to interconnect the APs and connect them to the Internet— the backhaul network.

Even with fewer APs, it is very expensive to provide T1, DSL or Ethernet backhaul for each access point. For these deployments, wireless backhaul is an attractive alternative and a good application for mesh networking. Wireless connections can be used between most of the APs and just a few wired connections back to the Internet are required to support the entire network.

Wireless links work better when there is clear line of sight between the communicating stations. Permanent wireless infrastructure mesh systems deployed over large areas can use the forwarding capabilities of the mesh architecture to go around physical obstacles such as buildings. Rather than blasting through a building with high power, a wireless mesh system will forward packets through intermediate nodes that are within line of sight and go around the obstruction with robust wireless links operating at much lower power. This approach works very well in dense urban areas with many obstructions.

Fig 1.9 : Meshing Around Obstructions

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There are many different types of mesh systems and they often get lumped together. Since early Wireless mesh systems were focused on mobile ad-hoc networks, many people assume that wireless mesh systems are low bandwidth or temporary systems that can not scale up to deliver the capacity and quality of service required for enterprise, service provider and public safety networks. That is not the case. Engineered, planned and deployed effectively, wireless mesh networks can scale very well while still offering a cost-effective evolution strategy that preserves the network investment. Understanding the strengths and weaknesses of single, dual, and multi-radio mesh options is the first step.

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1.3.2 Single radio wireless mesh:

In a single-radio mesh, each mesh node acts as an AP that supports local Wi-fi client access and forwards traffic wirelessly to other mesh nodes. The same radio is used for access and wireless backhaul. This option represents the lowest cost entry point in the deployment of a wireless mesh network infrastructure. However, because each mesh AP uses an omni-directional antenna to allow it to communicate with any of its neighbor APs, almost every packet generated by local clients must be repeated on the same channel to send it to at least one neighboring mesh AP. The packet is then forwarded to another node in the mesh and ultimately to a node that is connected to a wired network.

In a single-radio Wi-fi mesh network, all clients and mesh APs must operate on the same channel and use the 802.11 Media Access Control protocol. As a result, the entire mesh ends up acting like a single, giant access point—all of the mesh APs and all of the clients must contend for a single channel. This shared network contention and interference reduces capacity further and introduces unpredictable delays in the system as forwarded packets from mesh APs and new packets from clients contend for the same channel.

Figure 1.10: Single-radio Mesh Cluster

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In the above case, contention and interference would reduce the capacity available for client access beyond what we have described in the string of APs examples previously discussed. Large coverage mesh APs in these systems has high power radios and high gain antennas. The mesh APs can hear each other at a much greater range than they can hear the clients they support, because most Wi-fi client devices are low power with low gain antennas. In this cluster, AP3 can hear all the other APs except for AP5.All traffic for the entire mesh network flows through AP3 so it will frequently hold off the other APs, limiting their ability to handle traffic from their local clients. A more complicated formula is required to characterize the impact of neighboring mesh APs in a shared backhaul network as well as the mesh forwarding. The capacity in a single-radio mesh is limited by both access and backhaul issues. Optimizing the mesh forwarding protocol will not solve the problem. The basic capacity is too low and adding more mesh nodes makes it worse—no matter how perfect the mesh protocol.

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Single-radio solutions offer the lowest cost entry point in the deployment of mesh networks. In an infrastructure network, single radio mesh systems are best used for small mesh clusters of a few nodes. Larger systems may be created by providing wired backhaul to one of the nodes in each cluster or using wireless backhaul links to aggregate multiple clusters. Single radio mesh solutions can also be the right approach for mobile, ad hoc peer-to-peer wireless networks where the emphasis is on basic connectivity or used for large sensor network and meter reading networks where the data rate is very low.

1.3.3 Dual-Radio Wireless Mesh:

The capacity and scaling ability of wireless mesh infrastructure networks can be improved by using APs that have separate radios for client access and wireless backhaul. In a dual-radio mesh, the APs have two radios operating on different frequencies. One radio is used for client access and the other radio provides wireless backhaul. The radios operate in different frequency bands, so they can run in parallel with no interference. A typical configuration is 2.4 GHz Wi-fi for local access and some flavor of 5 GHz wireless for backhaul. Since the mesh interconnection is performed by a separate radio operating on a different channel, local wireless access is not affected by mesh forwarding and can run at full speed.

However, in a dual radio mesh the wireless backhaul is a shared network so it is subject to the same network contention issues that hamper the single radio mesh. The contention on the backhaul network limits capacity and creates additional latency making the dual radio approach inappropriate for voice traffic. The backhaul mesh in dual-radio mesh architectures is usually a shared network running the 802.11 MAC protocol. With only one radio dedicated to backhaul at each node, all of the mesh APs must use the same channel for connectivity to the backhaul mesh. Parallel operation on the backhaul

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network is not possible, as most of the APs hear multiple other mesh APs. So they must contend for the channel and at the same time generate interference for each other. The result is reduced system capacity as the network grows.

Fig 1.11: Dual-Radio Wireless Mesh, String of Mesh APs

Dual-radio systems are a big improvement over single-radio mesh designs and represent a logical Evolution in the growth of a mesh network. However, dual-radio systems alone don‘t scale to metro dimensions and the high and unpredictable latency on the shared backhaul network makes them a poor candidate for voice over Wi-fi.

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1.3.4 Multi-Radio Wireless Mesh:

Like a dual-radio wireless mesh, a multi-radio wireless mesh separates access and backhaul. It goes a step further, however, to provide increased capacity by addressing the shared backhaul Network issues that limit the dual-radio mesh architecture. In a multiradio wireless mesh, multiple radios in each mesh node are dedicated to backhaul. The backhaul mesh is no longer a shared network, since it is built from multiple point-to-point wireless links and each of the backhaul links operates on different independent channels. This type of multi-radio design is called a multiple point-to-point mesh. It is possible to create very rich mesh topologies with this multi-radio approach and just a few backhaul radios at each node.

Fig 1.12: Multi-Radio Wireless Mesh, String of APs

When used for backhaul in this fashion, the performance of a multi-radio mesh is similar to switched, wired connections. The mesh radios operate independently on different channels so latency is very low. There are only two nodes per mesh link, so contention is

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very low. In fact, it is possible to run a customized point to point protocol that optimizes throughput in this simple two-node contention-free environment. These dedicated point to point links are usually in the unlicensed 5.8 GHz band and based on 802.11a chipsets today. In the near future this will be a good application for 802.16d WiMAX. These preWiMAX wireless links have a potential throughput of approximately 25 Mbps. Performance in a multi-radio mesh is much better than the dual-radio or single-radio mesh approaches. The mesh delivers more capacity and continues to scale as the size of the network is increased—as more nodes are added to the system, overall system capacity grows.

1.3.5 Advantages of Multi-radio mesh approach:

There are many other advantages of the multi-radio mesh approach• Co-existence—most large wireless meshes today are designed to support Wi-fi clients in the 2.4 GHz band. There are many other Wi-fi devices out there. It is important for large infrastructure to fit into the RF environment. A single-radio mesh must use the same channel throughout the system. (Similarly, the backhaul mesh in a dual-radio system uses the same 5 GHz channel for the whole system.) It is unlikely that this channel will be the best at each location in a large network. A multi-radio mesh is much more flexible. Each access radio can be assigned a different channel, so the co-existence problem is isolated to the coverage area of a single mesh AP—not the whole system. Multi-radio meshes fit into their environment and share the unlicensed spectrum better. • Interference—Multi-radio meshes are very flexible in terms of channel assignment on the access or backhaul radios. They can adapt to interference because each access radio can be set to the channel that is least used in a given area. The backhaul network consists of point-to-point links. They use directional antennas that have high gain, but they project their signals in a narrow pattern in a specific direction. This minimizes the impact of the

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multi-radio backhaul mesh on other systems in the area. Multi-radio meshes have very little self interference because of flexible channel assignment and multiple radios operating on different channels at the same time. Both dual-radio and single-radio meshes cause self-interference, since all the nodes in the mesh must share a common channel for backhaul. In addition, interference from external networks in one location will disrupt service across and entire dual- or single-radio mesh network. • Latency—the dedicated point-to-point links in the multi-radio mesh keep backhaul latency low and predictable. Single-radio mesh and dual-radio mesh approaches have a shared backhaul network using a contention based protocol with unpredictable latency. Multi-radio mesh is suitable for voice applications, the others are not.

1.3.6 Examples WiMAX/Wi-Fi Multi-band Dual Radio: 1.3.6.1 Netkrom Technology 1.3.6.1.1 Description: The WiMAX/Wi-Fi Multi-band Dual Radio now covers 700MHz to 6.1GHz, including the popular unlicensed band (2.4/5GHz 802.11a/b/g Standard), 700MHz Non Line of Sight Frequency Band, 900MHz Non Line of Sight unlicensed band, 2.3 to 2.7 MMDS Licensed band, 3.4 to 3.6Ghz Licensed band, new 3.65GHz Unlicensed band, 4.9GHz Public Safety Band, 5.150 to 5.350GHz UNII FCC US Band, 5.470 to 5.725GHz ETSI Europe Band, 5.725 to 5.850GHz ISM FCC US Band, Special Wideband Range from 4.9 to 6.1GHz and future Licensed and Unlicensed Bands. The WiMAX/Wi-Fi Multi-band Dual Radio comes with 2 Radio Slots to select between several Mini PCI modules the frequency you need, high output power and firmware with advanced software characteristics based on Linux OS allowing to cover long distances up to 50 miles or 80 Km. All of these characteristics transform this radio into the most complete and advanced of the world.

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With prominent 108 Mbps data transfer rate (45 Mbps real speed) and up to 1Watt output power, you can forget about the word "interference". The WiMAX/Wi-Fi Multi-band Dual Radio is the next generation of Wireless equipments. 1.3.6.1.2 The WiMAX/Wi-Fi Multi-band Dual Radio Working Modes: • Access Point (for Point to Point and Multipoint Link, HotSpot, Mesh Networks, WISP Base • •

Station

WDS

(Wireless

Repeater

and

Distribution (for

Backhaul

System

wireless

for

Mesh

extended

applications) Networks

applications)

range

applications)

• AP Client (for Point to Point and Multipoint Link, Wireless Client and Backhaul applications) • Station (for Point to Point and Multipoint Link and Wireless Client applications)

1.3.6.1.3 Features: Multiple unlicensed and licensed band 700MHz to 6.1GHz (Choose the Frequency You Need!) Data transfer rate up to 108 Mbps on Turbo mode Work as Wireless Base Station, Hotspot AP, Mesh AP, Wireless Client, Backhaul and Repeater High power modules up to 1Watt for long distance links 50 miles or 80 Km. Long distance parameters and output power regulation High CPU power for high-speed connection Perfect design and characteristics for industrial outdoor use (waterproof) Complete compatibility with any IEEE network and future WiMAX Advanced network functions (IP Routing, Firewall, DHCP, NAT, Bandwidth Management, QoS, etc) Advanced security features WEP (64,128 bit), WPA1 & WPA2 Free NETKROM NMS - Network Management System

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Carrier class radio for extreme environment -60 to 230C

1.3.6.1.4 Applications:

Fig 1.13: Point To Point Link

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Fig 1.14: Point to Multipoint Link

1.3.6.2 BelAir100S Strand-Mounted Wireless Multi-service Node

The BelAir100S is a two-radio wireless multi-service node designed for strand-mounting on existing cable infrastructure. It supports DOCSIS® 2.0 and Euro-DOCSIS 2.0 interfaces and is plant-powered at 40 to 90 V AC. It provides mobile broadband support for Wi-Fi, WiMAX, Cellular, and 4.9 GHz Public Safety spectrums. Offering true standards-based seamless mobility, the BelAir100S ensures that subscribers do not experience service interruptions to critical applications, like voice and video, as they move throughout the wireless mesh network.

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Fig 1.15: The Dual Bel-Air Radio

1.3.6.2.1 Features • Modular dual-radio architecture • Supports Wi-fi and WiMAX • Seamless mobility for uninterrupted Service • Network management via CLI, WEB Or BelView NMS • 10/100BASE-TX or 100BASE-FX Ethernet interfaces • DOCSIS 2.0, Euro-DOCSIS 2.0

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1.3.6.2.2 Dual-radio architecture:

The dual-radio design of the BelAir100S provides support for Backhaul Radio Modules (BRMs), WiMAX Radio Modules (WRMs) and Access Radio Modules (ARMs) in the same wireless mesh node. The BelAir100S can be configured with a backhaul (BRM or WRM) radio module and access radio module (ARM) for traditional wireless mesh; or with any combination of dual BRMs or WRMs for a more resilient backhaul only deployments.

Wireless radio modules: The BelAir100S can support any combination of ARMs and BRMs, providing the ideal flexibility and capacity for large scale wireless mesh networks. The ARMs and BRMs support a broad range of Wi-fi (IEEE 802.11a/b/g),WiMAX (IEEE 802.16d), 4.9 Public Safety and Cellular (via a T1/E1 Circuit Emulation Module) applications making it the most versatile solution on the market for providing multi-service capabilities over a wireless mesh network.

Layer 2 networking capabilities: The BelAir100S has an integrated Layer 2 Switch engine that provides extensive QoS, VLAN, Network Security and Traffic Management capabilities that are necessary for transporting mission-critical, time-sensitive applications like voice and video.

Network Management: The BelAir100S can be managed via a Command Line Interface (CLI), WEB GUI or with BelAir Networks BelView Network Management System (NMS). Both CLI and WEB GUI provide for device level support, and BelView NMS provides complete network-wide support for Fault, Configuration and Performance Management. BelView NMS works on either Windows XP or SUN Solaris platforms and can also be integrated

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into other management systems like HP Open View or IBM Net View. BelAir Networks is the leading provider of mobile broadband mesh networking solutions. Cities around the world rely on BelAir to deliver industry-leading Broadband performance and scalability, and carrier class capacity and reliability. BelAir Networks teams with world-class global partners to deploy proven, cost-effective wireless broadband mesh networks

1.3.7 CONCLUSION:

Capacity in a wireless mesh infrastructure is affected by the mesh forwarding performance, shared network contention and self interference of the mesh APs. It is important to consider all of these issues when analyzing these systems.

Single radio wireless mesh, representing the lowest cost entry point in the deployment of a mesh network, is low capacity and will not effectively scale to implement a complete large network. Single radio mesh is best used in small mesh clusters at the edge of a network.

The dual-radio mesh architecture represents the logical evolution in the growth of a mesh network. Dual-radio systems alone don‘t scale to metro dimensions.

Multi-radio mesh systems separate wireless access and backhaul, and use dedicated point-to-point links to form the wireless backhaul mesh. This eliminates both in-channel mesh forwarding and shared backhaul network contention overhead. The result is a high capacity system that can scale to support large networks with broadband service for many users.

In the real world, large wireless networks require an integrated combination of the three meshes Approaches described. It is possible to deploy a very low cost, low capacity

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network based mostly on single-radio mesh with some multi-radio mesh nodes acting as aggregators for single radio mesh clusters. Over time, the network can be upgraded with more capacity or better QoS by replacing single-radio mesh nodes at the edge with multiradio nodes. Network design should be customized to meet the application requirements and budget by using the appropriate mix of the different wireless mesh approaches. 1.4 MOTIVATION: Different countries have carried out different studies to test the viability of WMNs.

1.4.1 Case 1: AirJaldi, Dharamsala

The Air Jaldi (The dharamsala community wireless mesh project) came in direct response to international interest in the Dharamsala Community Wireless Mesh Network. It was developed in cooperation with the Dharamsala Information Technology Group, an organization chaired by the Tibetan Computer Resource Center and some of the region‘s leading information technology professionals. The Mesh backbone includes over 30 nodes, all sharing a single radio channel. Broadband Internet services are provided to all mesh members. The total upstream Internet bandwidth available is 6Mbps. There are over 2000 computers connected to the Mesh, and about 500 have Internet access.

To bridge over an array of economic, educational, geographic and social divides The vision of this project is to harness community wireless network for development in and around Dhramshala which interconnects thousands of computers within difficult mountainous terrain covering a radius of 50 km and provide broadband internet access , VOIP telephony, file sharing, off-site backup and video based application. The challenges that were faced by the team were Poor ICT infrastructure Difficult terrain

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Scattered population. . The dhramshala wireless mesh project has: Exceptional affordability, performance and features. Suitability for rural settings and communities. Modular design which enables expansion in line with needs and demand

Results:

Air jaldi led to a wireless mesh area network in and around dharamsala which: Interconnects thousands of computers within difficult mountain terrain covering a radius of around 50 km. Provide broadband internet access, VOIP telephony, file sharing, offsite backup and video based application.

By integrating multiple existing open-source software projects, with a little on-site tuning the team managed to build one of Asia's largest wireless mesh networks

1.4.2 Case 2: Nepal wireless project

The Nepal Wireless Networking Project started as a pilot project from a small and remote area of Nepal with the help of foreign supporters and volunteers. Several testing were done in 2002 to find out if it is possible to connect the villages to the nearest ISP in Pokhara. The test was successful. 106

In September 2003, five villages were connected and the network was expanded to two more villages later on. So far seven villages are networked. The network is running despite some problems mainly the shortage of power and wireless devices. At present 13 villages connected in the network. The villages are wirelessly networked and connected to an ISP WorldLink, which is approx. 22 air miles (~34 km) away from Relay Station 1 in a city

Target: The target of this project is the people living in a Himalayan region of Nepal where there is almost no chance of getting the modern means of communication in near future. We are introducing the information technology to villagers, most of whom had never seen computers until a few years ago. Most of the villagers still have no idea as what the uses of the computers are. For the villagers, a computer is no more than a "mysterious box".

Challenges:

The biggest challenges until September 2006 for this project were to find ways to work in the absence of flexible government law. Besides, the biggest problem has been the criminalization of VOIP technology in Nepal. The secondary problems were the ready availability of the wireless equipment in Nepal. Sometime the team had to wait for several months just to get a small piece of equipment. Especially problematic are antennas and small accessories. Apart are obviously some technical problems also. Nepal Wireless Networking Project along with individuals and organization working in the field of wireless networking has been lobbying for opening up of VOIP and provision for rural and community ISPs in Nepal. VOIP technology itself is difficult to use in Nepal. The technology itself has been criminalized in Nepal. Effort has been to open up use of VOIP so that it can be used freely in our own network.

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In rural Africa a satellite link (VSAT) often provides the only possible way to connect a local mesh network to an upstream network provider offering global connectivity. Satellite links suffer from higher than normal latency and affect latency sensitive services such as telephony.

A number of pilot mesh projects across the world (Freifunk OLSR Experiment in Berlin, Germany, the Dharamsala mesh in India and Peebles Valley in South Africa) have demonstrated that a community can establish and maintain a wireless mesh network and have access to a range of modern information and communication services. These services include telephony (Voice over Internet Protocol), instant messaging, electronic mail, web access, multimedia services and service delivery (e.g. telehealth and elearning).

1.4.3 Case 3: Africa

Today, more than two billion people in the developing world live in rural and remote locations with little or no access to basic information and communications technologies (ICT), such as telephones, computers, or the Internet. Yet access to these technologies can improve their lives in simple, yet profound ways – providing better economic opportunities, helping enforce human rights, educating children, and even saving lives. Inveneo is a non-profit social enterprise whose mission is to get ICT tools into the hands of the organizations and people who need them most — those in remote and rural communities in the developing world. To do this, we create and sell affordable and highly sustainable ICT systems designed specifically for the many challenges these organizations face in locations where electrical power is:

not available or not dependable power is very expensive

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heat, dust, moisture, and humidity are common little access to affordable communications lack of trained technicians for local support

The key components of the Inveneo Communications System include:

Inveneo Computing Station (Ultra-low power desktop computer with LCD monitor, 12V adapter) Inveneo Communications Station (Ultra-low power desktop computer with LCD monitor, 12V adapter, VoIP telephone) Inveneo Hub Station (Ultra-low power server with central data storage, access gateway, firewall) Long-distance wireless connectivity (WiFi networking via directional antenna and outdoor wireless router) VoIP telephony (Software-based IP PBX system with standard telephone handsets) Operating system and software (Open Source software, Windows also supported)

How it all works together

The Inveneo Communication System can be used for a 10-unit school computer center or a complete regional network connecting offices and local-area networks as much as 100 kilometers apart. In both situations, the Inveneo solution can provide the affordable access to information and communication that organizations and communities need in rural and remote parts of the world.

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The first step in setting up an Inveneo Communications System is to map out the network with an Inveneo Certified ICT Partner (ICIP). These partners are trained and certified ICT professionals and small-business entrepreneurs. They provide installation and support for the organizations Inveneo serves, improving the affordability and level of support dramatically.

Currently Inveneo has projects completed or underway in Uganda, Rwanda, Ghana, Guinea Bissau, Mali, South Africa, Cameroon, Gabon, and Burkina Faso. These projects serve schools, economic development groups, telecenters, micro-finance programs, and relief camps.

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1.4.4 Case 4: California SOUTHERN CALIFORNIA TRIBAL CHAIRMEN‘S ASSOCIATION

A Consortium of 18 federally recognized tribal sovereign nations in San Diego County with a combined population of 15,000 People, 8,900 of which live on these reservations.

TDV NETWORK OVERVIEW:

250 miles of point to point and point to multipoint links 15 backbone and relay sites 20 network servers 65 building connections 1000+ computers and networks peripherals connected to TDV‘s network. 1,500+ users 45mbs of bandwidth(DS3: fiber at data center)

THE NETWORK’S SUCCESS Tribally owned and operated All on tribal reservation land Investigation, design, and implementation done completely by tribal members Created opportunity for tribal Digital Village Community Members to gain exposure to Information Technology and Web Exposure Provided opportunities for tribal youth to have job training experience in previously non- existing career choices in the Computer Industry Growing a Community Web Portal

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ECONOMIC SUCCESS • Training of the Tribal Youth. • Spanning the Digital Divide to Communities • Training Tribal Members in technology •CISCO Training •A+ Computer Repair and Networking •MCSE courses towards an IT career • Creating technology proficient tribal members to obtain hi-tech jobs

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• Creating access to on-line resources, previously unavailable • Allowing the tribal community to empower themselves in technology business building.

SURVEY OF WMCN IN SMIT AND DESIGN STRATEGY

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CHAPTER 1

INTRODUCTION Wireless devices have been gaining popularity in recent years. The widespread reliance on networking in business and the meteoric growth of the Internet and online services are strong testimonies to the benefits of shared data and shared resources. Cellular phones and other wireless communication devices have driven demand for new wireless technology. While traditional wired solutions provide a sense of reliability, convenience has become a large part of consumer‘s needs. With wireless LANs, users can access shared information without looking for a place to plug in, and network managers can set up or augment networks without installing or moving wires. Wireless networks are used to augment rather than replace wired networks and are most commonly used to provide last few stages of connectivity between a mobile user and a wired network.

1.1 BUILDING LAN Computer networks can be built using either wired or wireless technology. Wired Ethernet has been the traditional choice, but Wi-fi wireless technologies are gaining ground fast. Both wired and wireless can claim advantages over the other; both represent viable options for local area networks (LANs). Wired and wireless networking can be compared in five key areas: Ease of installation

Total cost

Reliability

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Performance

Security

1.1.1 Wired Technology

Wired technology first became popular in the early 1900's with the introduction of the telephone network. Using physical wires means that electronic signals are being transmitted over a metal conductor. Currently, this is the most reliable way to transmitting/receiving data or voice. The Internet itself, transmits a large amount of data through fiber optic cabling but also employs a large amount of lines that run over standard copper wiring. For purposes of this writing, "wired" refers to copper wiring and does not include fiber optic technologies.

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Table 1.1 Pros and Cons of Wired Technology Pros

Cons

Reliable - Not affected by other wireless

Affected by moisture and other weather

signals (portable/cellular phones,

conditions

microwaves, etc) Price (wire is cheap!)

Can be affected by noise generated by machinery and magnetics

High Life Expectancy

Length of wire runs limited

1.1.1.1 Pro's

For the most part, wired technology is very reliable. The telephone system operates using wired technology and provides a 99.999% uptime. This is also known as the "five 9s of reliability." Although wire is susceptible to interference by loud machinery (A/C units, electric motors, etc) various solutions, such as shielded cable can be used to solve these problems. Shielded or armored wiring is used to protect against weather and other types of negative externalities. Compared to wireless solutions, wired equipment is generally cheaper, as well as the cost of maintenance. Generally, copper wiring has a very long life expectancy. The QoS is excellent because wired connections eliminate the need for establishing an end-to-end connection every time. Speed is also a huge advantage of using wired connections.

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1.1.1.2

Con's

On the negative side, wired connections are not always realistic. Some rural areas are still not wired for broadband Internet connections. This forces users to subscribe to satellite access. Ethernet cables can run a maximum of 100 meters before the signal needs to be boosted. This can cause problems if you don't have an environment that allows this luxury. The longer the cable is, the more signal loss occurs and the signal travels down the wire. Special cables have been developed to help preserve the strength of the signal. However, the use of such technology usually comes at a significantly higher price.

1.1.2 Wireless Technology

Wireless signals were fist used in transmitting AM and FM to television and radios in the early 1950's. The military has been using "line of sight" micro-wave towers for decades. The most common wireless technology is cellular phones. A wireless network is a flexible data communications system, which uses wireless media such as radio frequency technology to transmit and receive data over the air, minimizing the need for wired connections. Wireless networks use electromagnetic waves to communicate information from one point to another without relying on any physical connection. To extract data, a radio receiver tunes in one radio frequency while rejecting all other frequencies. The modulated signal thus received is then demodulated and the data is extracted from the signal. Wireless networks offer productivity, convenience, and cost advantages over traditional wired networks:

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Table 1.2 Pros and Cons of Wireless technology

Pro's

Con's Un-reliable - affected by other wireless signals

Convenient

(portable/cellular phones, microwaves, etc)

Range

Price

High Life Expectancy

Signals can be easily intercepted Speeds are much slower than wired QoS (Quality of Service)

1.1.2.1 Pro's On the pro side, wireless technology is very convenient. You do not have to worry about running wires in tight places, or obtaining low-voltage permits. The range of wireless technology can be impressive. While the equipment you use may break (just as wired equipment would) the signals themselves never break. Mobility: provide mobile users with access to real-time information so that they can roam around in the network without getting disconnected from the network. This mobility supports productivity and service opportunities not possible with wired networks. Installation speed and simplicity: installing a wireless system can be fast and easy and can eliminate the need to pull cable through walls and ceilings. Reach of the network: the network can be extended to places which can not be wired

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More Flexibility: wireless networks offer more flexibility and adapt easily to changes in the configuration of the network. Reduced cost of ownership: while the initial investment required for wireless network hardware can be higher than the cost of wired network hardware, overall installation expenses and life-cycle costs can be significantly lower in dynamic environments. Scalability: wireless systems can be configured in a variety of topologies to meet the needs of specific applications and installations. Configurations can be easily changed and range from peer-to-peer networks suitable for a small number of users to large infrastructure networks that enable roaming over a broad area.

1.1.2.2 Con's On the negative side, wireless technology suffers easily from interference. Other source of EM (electro-magnetic radiation) can cause problems for wireless signals, more frequently as compared to wired signals. High-end wireless equipments are costly. Installing the equipment can be tricky depending on the environment. Out-door antennas that may be adversely affected by temperature or humidity disturbing the signal. Wireless technology also has implications in regards to security. Wire-tapping can be done, but one must have physical access to a wire. However wireless signal can be intercepted by simply being the range of a wireless signal. Another problem is speed. While some wi-fi equipment producers claim they can transmit data at 108 Mbits/sec. Wireless speed is not even close to gigabit or 10 gigabit speeds that are attained using wires. Lastly, the quality of service is anything but effective. Wireless technology does not and probably never will operate in the five 9's of reliability.

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1.1.3 Wired vs Wireless

Table 1.3 Comparison of Wired and Wireless technology Wired

Wireless

Installation

moderate difficulty

easier, but beware interference

Cost

Less

more

Reliability

High

reasonably high

Performance very good

good

Security

reasonably good

reasonably good

Mobility

Limited

outstanding

1.2 TYPICAL WLAN INSTALLATION WLANs are used on college campuses and in office buildings. They can be set up in houses allowing multiple users to access one Internet connection. Resorts, apartment buildings and airports plan to offer WLAN access. Often the best use for WLANs are in places where LANs are not installed yet, like schools or public institutions that are slow to adopt new technologies. • Students holding class on a campus greensward access the Internet to consult the catalog of the Library of Congress. • Network managers in dynamic environments minimize the overhead caused by moves, extensions to networks, and other changes with wireless LANs. • Training sites at corporations and students at universities use wireless connectivity to ease access to information, information exchanges, and learning.

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• Network managers installing networked computers in older buildings find that wireless LANs are a cost-effective network infrastructure solution. • Trade show and branch office workers minimize setup requirements by installing preconfigured wireless LANs. • Warehouse workers use wireless LANs to exchange information with central databases, thereby increasing productivity. • Senior executives in meetings make quicker decisions because they have real-time information at their fingertips.

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CHAPTER 2

Wi-Fi

IEEE Project 802.11 met in 1980 and has specified LAN/MAN standards for a diverse array of networking environments and media. WiFi which stands for WIRELESS FIDELITY is the popular name for the wireless Ethernet 802.11b standard for WLANs. Wire line local area networks (LANs) emerged in the early 1980s as a way to allow collections of PCs, terminals, and other distributed computing devices to share resources and peripherals such as printers, access servers, or shared storage devices. One of the most popular LAN technologies was Ethernet. Over the years, the IEEE has approved a succession of Ethernet standards to support higher capacity LANs over a diverse array of media. The 802.11x family of Ethernet standards is for wireless LANs. WiFi LANs operate using unlicensed spectrum in the 2.4GHz ISM band & 5 GHZ U-NII bands. The current generation of WLANs supports up to 54 Mbps data rates within 100m of the base station. The ISM (Industrial, Scientific, and Medical) bands were originally reserved internationally for the noncommercial use of radio frequency (RF) electromagnetic fields for industrial, scientific, and medical purposes. More recently, they have also been used for license-free, error-tolerant communications applications such as cordless phones, Bluetooth, and Wireless WLAN. The U-NII (Unlicensed National Information Infrastructure) bands can be used by devices that will provide short-range, high-speed wireless digital communications. These devices, which do not require licensing, support the creation of WLANs and facilitate access to the Internet. The U-NII spectrum is located at 5.15 to 5.35 GHz and 5.725 to 5.825 GHz.

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WLANs are deployed in a distributed way to offer last-hundred-meter connectivity to a wire line backbone corporate or campus network. Typically, the WLANs are implemented as part of a private network. The base station equipment is owned and operated by the end-user community as part of the corporate enterprise, campus, or government network. In most cases, use of the network is free to the end-users (that is, it is subsidized by the community as a cost of doing business, like corporate employee telephones). Although each base station can support connections only over a range of a hundred meters, it is possible to provide contiguous coverage over a wider area by using multiple base stations. A number of corporate business and university campuses have deployed such contiguous WLANs. Still, the WLAN technology was not designed to support highspeed hand-off associated with users moving between base station coverage areas (the problem addressed by mobile systems). Wi-fi may be used with other wireless technologies to provide service over greater distances. This could be used to establish an affordable backhaul network for Wi-Fi deployments in rural or less dense areas The last 2 years have seen the emergence of a number of service providers that are offering Wi-Fi services for a fee in selected local areas such as hotels, airport lounges, and coffee shops. In addition there is a growing movement where individuals or organizations are providing open access to subsidized Wi-fi networks. In contrast to mobile, WLANs were principally focused on supporting data communications. However, with the growing interest in supporting real-time services such as voice and video over IP networks, it is possible to support voice telephony services over WLANs.

2.1 IEEE 802.11 ARCHITECTURE

Each computer, mobile, portable or fixed, is referred to as a station in 802.11.

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The difference between a portable and mobile station is that a portable station moves from point to point but is only used at a fixed point. Mobile stations access the LAN during movement. When two or more stations come together to communicate with each other, they form a Basic Service Set (BSS). The minimum BSS consists of two stations. 802.11 LANs use the BSS as the standard building block.

Figure 2.1 Adhoc Mode

A BSS that stands alone and is not connected to a base is called an Independent Basic Service Set (IBSS) or is referred to as an Ad-Hoc Network. An ad-hoc network is a network where stations communicate only peer to peer. There is no base and no one gives permission to talk. Mostly these networks are spontaneous and can be set up rapidly. AdHoc or IBSS networks are characteristically limited both temporally and spatially. When BSSs are interconnected the network becomes one with infrastructure. 802.11 infrastructure has several elements. Two or more BSSs are interconnected using a

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Distribution System or DS. This concept of DS increases network coverage. Each BSS becomes a component of an extended, larger network. Entry to the DS is accomplished with the use of Access Points (AP). An access point is a station, thus addressable. So, data moves between the BSS and the DS with the help of these access points. Creating large and complex networks using BSSs and DSs leads us to the next level of hierarchy, the Extended Service Set or ESS. With ESS is the entire network looks like an independent basic service set to the Logical Link Control layer (LLC). This means that stations within the ESS can communicate or even move between BSSs transparently. One of the requirements of IEEE 802.11 is that it can be used with existing wired networks. 802.11 solved this challenge with the use of a Portal. A portal is the logical integration between wired LANs and 802.11. It also can serve as the access point to the

Fig 2.2 Infrastructure Mode

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DS. All data going to an 802.11 LAN from an 802.X LAN must pass through a portal. It thus functions as bridge between wired and wireless.

2.2 IEEE 802.11 STANDARDS

The most critical issue affecting WLAN demand has been limited throughput. The data rates supported by the original 802.11 standards are too slow to support most general business requirements and slowed the adoption of WLANs. Recognizing the critical need to support higher data transmission rates. After 802.11b, standard 802.11a & another 802.11g has been approved. The original 802.11 wireless standard defines data rates of 1 Mbps and 2 Mbps via radio waves using frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS). FHSS and DSSS are fundamentally different signaling mechanisms and will not interoperate with one another. Using the frequency hopping technique, the 2.4 GHz band is divided into 75 1-MHz sub channels. The sender and receiver agree on a hopping pattern, and data is sent over a sequence of the sub channels. Each conversation within the 802.11 network occurs over a different hopping pattern, and the patterns are designed to minimize the chance of two senders using the same sub channel simultaneously. FHSS techniques are limited to speeds of no higher than 2 Mbps. This limitation is driven primarily by FCC (Federal Communications Commission USA) regulations that restrict sub channel bandwidth to 1 MHz. These regulations force FHSS systems to spread their usage across the entire 2.4 GHz band, meaning they must hop often, which leads to a high amount of hopping overhead.

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2.2.1 IEEE 802.11b

With 802.11b WLANs, mobile users can get Ethernet levels of performance, throughput, and availability. Addition of the 802.11b to the wireless LAN standard standardized the physical layer support of two new speeds, 5.5 Mbps and 11 Mbps. 802.11b systems interoperate with 1 Mbps and 2 Mbps 802.11 DSSS systems, but will not work with 1 Mbps and 2 Mbps 802.11 FHSS systems. The original 802.11 DSSS standard specifies an 11-bit chipping rate called a Barker sequence to encode all data sent over the air. Each 11-chip sequence represents a single data bit (1 or 0), and is converted to a waveform, called a symbol, that can be sent over the air. The inherent redundancy of each chip combined with spreading the signal across the 22 MHz channel provides for a form of error checking and correction; even if part of the signal is damaged, it can still be recovered in many cases, minimizing the need for retransmissions In addition to spreading the signal, modulation techniques are used to encode the data signal through predictable variations of the radio signal. IEEE 802.11 specifies two types of DPSK modulation for DSSS systems. The first is BPSK and the second is QPSK. Phase-shift keying (PSK), as the name implies, detects the phase of the radio signal. BPSK detects a 180-degree inversion of the signal, representing a binary 0 or 1. This method has an effective data rate of 1 Mbps. QPSK detects 90-degree phase shifts. This doubles the data rate to 2 Mbps. IEEE 802.11b adds CCK and packet binary convolutional coding (PBCC), which provides data rates up to 11 Mbps. The 5.5 Mbps rate uses CCK to encode 4 bits per carrier, while the 11 Mbps rate encodes 8 bits per carrier. Both speeds use QPSK as the modulation technique and signal at 1.375 Msps. This is how the higher data rates are obtained. To support very noisy environments as well as extended range, 802.11b WLANs use dynamic rate shifting, allowing data rates to be automatically adjusted to compensate for the changing nature of the radio channel. Ideally, users connect at the full 11 Mbps rate.

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However when devices move beyond the optimal range for 11 Mbps operation, or if substantial interference is present, 802.11b devices will transmit at lower speeds, falling back to 5.5, 2, and 1 Mbps. Likewise, if the device moves back within the range of a higher-speed transmission, the connection will automatically speed up again. Rate shifting is a physical layer mechanism transparent to the user and the upper layers of the protocol stack. The direct sequence signaling technique divides the 2.4 GHz band into 14 22-MHz channels. Data is sent across one of these 22 MHz channels without hopping to other channels. Adjacent channels overlap one another partially, with three of the 14 being completely non-overlapping. This is why only three IEEE 802.11b DSSS systems can be co-located. One of the more significant disadvantages of 802.11b is that the frequency band is crowded, and subject to interference from other networking technologies, microwave ovens, 2.4GHz cordless phones (a huge market), and Bluetooth. There are drawbacks to 802.11b, including lack of interoperability with voice devices, and no QoS provisions for multimedia content. Interference and other limitations aside, 802.11b is the leader in business, institutional wireless networking and home applications as well.

2.2.2 IEEE 802.11a

802.11a, is much faster than 802.11b, with a 54Mbps maximum data rate operates in the 5GHz frequency range and allows eight simultaneous channels.802.11a uses Orthogonal Frequency Division Multiplexing (OFDM), an encoding scheme that offers benefits over spread spectrum in channel availability and data rate. Channel availability is significant because the more independent channels that are available, the more scalable the wireless network becomes. 802.11a uses OFDM to define a total of 8 non-overlapping 20 MHz channels across the 2 lower bands.

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IEEE 802.11a (5 GHz) uses OFDM as its frequency management technique and adds several versions of quadrature amplitude modulation (QAM) in support of data rates up to 54 Mbps. OFDM is based on a mathematical process called Fast Fourier Transform (FFT). FFT enables 52 channels to overlap without losing their individuality or orthogonality. Overlapping channels is a more efficient use of the spectrum and enables them to be processed at the receiver more efficiently. IEEE 802.11a OFDM divides the carrier frequency into 52 low-speed sub carriers. Forty-eight of these carriers are used for data and four are used as pilot carriers. The pilot sub carriers allow frequency alignment at the receiver. One of the biggest advantages of OFDM is its resistance to multipath interference and delay spread. Multipath is caused when radio waves reflect and pass through objects in the environment. Radio waves are attenuated or weakened in a wide range depending on the object's materials. Some materials (such as metal) are opaque to radio transmissions. The cluttered environment would be very different from an open warehouse environment for radio wave transmission and reception. This environmental variability makes it hard to estimate the range and data rate of an IEEE 802.11 system. Because of reflections and attenuation, a single transmission can be at different signal strengths and from different directions depending on the types of materials it encounters. This is multipath. IEEE 802.11a supports data rates from 6 to 54 Mbps. It utilizes BPSK, QPSK, and QAM to achieve the various data rates. Delay spread is associated with multipath. Because the signal is traveling over different paths to the receiver, the signal arrives at different times. This is delay spread. As the transmission rate increases, the likelihood of interference from previously transmitted signals increases. Multipath and delay spread are not much of an issue at data rates less than 3 or 4 Mbps, but some sort of mechanism is required as rates increase to mitigate the effect of multipath and delay spread. In IEEE 802.11b, it is CCK modulation. In 802.11a, it is OFDM. The IEEE 802.11g specification also uses OFDM as its frequency management mechanism. All wireless LANs use unlicensed spectrum; therefore they're prone to interference and transmission errors. To reduce errors, both types of 802.11 automatically reduce the

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Physical layer data rate. IEEE 802.11b has three lower data rates (5.5, 2, and 1Mbit/sec), and 802.11a has seven (48, 36, 24, 18, 12, 9, and 6Mbits/sec). Higher (and more) data rates aren't 802.11a's only advantage. It also uses a higher frequency band, 5GHz, which is both wider and less crowded than the 2.4GHz band that 802.11b shares with cordless phones, microwave ovens, and Bluetooth devices. The wider band means that more radio channels can coexist without interference. Each radio channel corresponds to a separate network, or a switched segment on the same network. One big disadvantage is that it is not directly compatible with 802.11b, and requires new bridging products that can support both types of networks. Other clear disadvantages are that 802.11a is only available in half the bandwidth in Japan (for a maximum of four channels), and it isn't approved for use in Europe, where HiperLAN2 is the standard.

2.2.3 IEEE 802.11g

Though 5GHz has many advantages, it also has problems. The most important of these is compatibility. The different frequencies mean that 802.11a products aren't interoperable with the 802.11b base. To get around this, the IEEE developed 802.11g, which should extend the speed and range of 802.11b to be fully compatible with the older systems. The standard operates entirely in the 2.4GHz frequency, but uses a minimum of two modes (both mandatory) with two optional modes. The mandatory modulation/access modes are the same CCK (Complementary Code Keying) mode used by 802.11b (hence the compatibility) and the OFDM (Orthogonal Frequency Division Multiplexing) mode used by 802.11a (but in this case in the 2.4GHz frequency band). The mandatory CCK mode supports 11Mbps and the OFDM mode has a maximum of 54Mbps. There are also two modes that use different methods to attain a 22Mbps data rate--PBCC-22 (Packet Binary Convolutional Coding, rated for 6 to 54Mbps) and CCK-OFDM mode (with a rated max of 33Mbps).

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The obvious advantage of 802.11g is that it maintains compatibility with 802.11b (and 802.11b's worldwide acceptance) and also offers faster data rates comparable with 802.11a. The number of channels available, however, is not increased, since channels are a function of bandwidth, not radio signal modulation - and on that score, 802.11a wins with its eight channels, compared to the three channels available with either 802.11b or 802.11g. Another disadvantage of 802.11g is that it also works in the 2.4 GHz band and so due to interference it will never be as fast as 802.11a.

2.3 COMPETING TECHNOLOGIES TO IEEE 802.11

2.3.1 HiperLAN2

HiperLAN2 is a wireless LAN technology operating in the license free 5 GHz (5.4 to 5.7 GHz) U-NII band., HiperLAN2 is designed to carry ATM cells, IP packets, firewire packets, and digital data from cellular phones. Whereas 802.11a is a form of wireless Ethernet, HiperLAN2 is commonly regarded as wireless ATM. 802.11a is connectionless Ethernet-like standard. There isn‘t a persistent connection between client and server. HiperLAN2 is based on connection-oriented links, though it can accept Ethernet frames. 802.11a is optimized for data communications, as are all standards based on 802.11. HiperLAN2 is best suited to wireless multimedia because of its integrated Quality of Service (QoS) support. The 802.11a group is trying to incorporate the best features of HiperLAN2 within its own standards. One merged European standard will emerge and it will most likely be 802.11a incorporating the best features of HiperLAN2.

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2.3.2 HomeRF

HomeRF, Home Radio Frequency, was the first practical wireless home networking technology and came out in mid-2000. It uses radio frequencies to transmit data over ranges of 75 to 125 feet. It uses SWAP (Shared Wireless Access Protocol), which is a hybrid standard, developed from IEEE 802.11. SWAP can connect up to 127 network devices and transmits at speeds up to 2Mbps. The major disadvantage to a HomeRF network is data transmission speed. 2Mbps is fine for sharing files and printing normal files. It is insufficient for streaming media and printing or transferring large graphic files. HomeRF is a less expensive wired network solution& does not interfere with Bluetooth and is better for transmitting voice signals.

Table 2.1 Wireless local areas networking technologies Application Key Tech

Dataspeeds

The Good

The Bad

(Max/Avg) Enterprise

802.11

Networking 802.11b

The Bottom Line

2 Mbps/ 1.2

Wireless local

Slow, expensive, poor

Good start but

Mbps

area networking security

superceded

11 Mbps/5.5

Faster, cheaper, Security is not very

Viable for

Mbps

stronger than

good more expensive

widespread

802.11

than wireline

enterprise adoption

802.11g

22 Mbps

Faster than

competing technologies supersede

802.11b

could divide vendor

802.11b

focus

within 18 months

132

Enterprise

802.11a

54 Mbps/24

Faster than

New modulation

Higher cost

and

Mbps, future

802.11b and

scheme and different

equipement

Metropolitan

iterations

802.11g

frequency band,

Area

being planned

unlikely to be backward

Networking

to support up

compatible with

to 100 Mbps

802.11b. No support for voice in initial specification. Costs not proven, likely to be relatively expensive

HiperLAN/2 54 Mbps/24 Mbps

supports

Expensive. Direct

Will struggle

connection-

competitor with

against

oriented

802.11a; likely to be the competition

services such as loser in a head-to-head from 802.11a

Home

HomeRF

Networking

voice

competition

Fast, cost-

Unlikely to be

Some

Mbps; planned effective home

established outside

penetration,

future

home environment

but fails to

2 Mbps/1

networking

iterations will standard

become

support up to

mainstream

10 Mbps Table 2.1(contd.)

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CHAPTER 3

CONSIDERATIONS IN CELL DESIGN

The successful deployment of an 802.11 system requires design, planning of cells. Following should be taken into consideration while designing

3.1 Protocols

Three primary standards-based protocols are currently available: 802.11b, 802.11a, and 802.11g.

3.1.1 IEEE 802.11b It allows for the wireless transmission of approximately 11 Mbps of raw data at indoor distances up to 300 feet and outdoor distances of 20 miles in point-to-point usage of the 2.4 GHz band. The distance depends on impediments, materials, and line of sight. 802.11b is the most commonly deployed standard in public short-range networks, such as those found at airports, coffee shops, hotels, conference centers, restaurants, bookstores, and other locations.

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3.1.2 IEEE 802.11a

RF interference is much less likely because of the less crowded 5 GHz bands But equipment designed for the 5.1 GHz band has an integrated antenna and is not easily modified for higher power output and operation on the other two 5 GHz bands The 5.15 to 5.25 GHz portion of the U-NII band is intended for indoor, shortrange networking devices. The FCC adopted a 200 milliwatt (mW) effective isotropic radiated power (EIRP) limit to enable short-range WLAN applications in this band without causing interference to mobile satellite service (MSS) feeder link operations. Devices operating between 5.25 to 5.35 GHz are intended to provide communications within and between buildings, such as campus-type networks. UNII devices in the 5.25 to 5.35 GHz frequency range are subject to a 1-watt EIRP power limit. The 5.725 to 5.825 GHz portion of the U-NII band is intended for community networking communications devices operating over longer distances. The FCC permits fixed, point-to-point U-NII devices to operate with up to a 200-watt EIRP limit

3.1.3 IEEE 802.11g The range at 54 Mbps is less than the existing 802.11b APs operating at 11 Mbps. As a result, if an 802.11b cell is upgraded to 802.11b, the high data rates will not be available throughout all areas. You'll probably need to add additional APs and replan the RF frequencies to split the existing cells into smaller ones. 802.11g offers higher data rates and more multipath tolerance. 135

Table 3.1 Frequency bands and associated power limits Frequency range

Bandwidth

(MHz)

(MHz)

Max. power at antenna

2400-

83.5

1 W (+30 dB above 1 4 W (+36 Point to point; point to

2483.5

5150-5250

100

Max. EIRP

Notes

milliwatt [dBm]), 1 W dBm)

multipoint

(+30 dBm)

3:1 rule

50 mW

200

following

mW Indoor use, must have

(+23 dBm) integral antenna 5250-5350

100

250 mW (+24 dBm)

1 W (+30 dBm)

5725–5825 100

1 W (+30 dBm)

200

W

(+53 dBm)

Although more interference exists on the 2.4 GHz band, 802.11g may be the protocol of choice for the best range and bandwidth combination. It's also upwardly compatible with 802.11b equipment.

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3.2

MAKING A CHOICE

It depends on the application and other design considerations. Frequency hopping offers superior reliability in noise and multipath fading environments. Direct sequence can provide higher over-the-air data rates. OFDM offers multipath tolerance and much higher data rates 802.11b is compatible with most of the public access locations. 802.11a is the best to solve interference cases and has great throughput 802.11g promises the best range and throughput combination of all the solutions

3.3

SITE SURVEY

3.3.1 Outdoor Site Survey The Fresnel Zone can be checked against a topographical view of the point-topoint shot. Check for trees or buildings that might block the path. Using the location of both endpoints, one can calculate a bearing and tilt angle to point the antenna. With the help of spectrum analyzer select the channel that has the least amount of noise.

3.3.2 Indoor Site Survey Study the floor plans of the structure. Look for existing RF sources Using a laptop with a site survey tool, find the points where 20 dB SNR is observed. This becomes the cell boundary. Place the trial AP so that its 20 dB

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SNR cell boundary overlaps the one identified by the first trial location. Continue to lay out cells until the whole structure is covered.

3.4

FREQUENCY ALLOCATION

For a simple project like one or two APs, simply assign the least used frequencies from the site survey. For more complex projects involving three or more APs, pick a frequency reuse pattern for the frequencies that are used for the project; start with the most complicated part of site survey and start assigning frequencies. Plan the location of APs initially for coverage, not capacity. Avoid overlapping channels if possible. However, if an area has to be overlapped, plan it such that it is naturally an area where the most capacity would be required, such as in a library, conference room, or lecture hall.

3.5 EQUIPMENT SELECTION 3.5.1 Buy the Right AP Depending on the application, several choices of Wi-fi APs are available. Such as an AP; an AP and router combination; and an AP, router, and print server combination

3.5.2 Using Two Antennas for Diversity Diversity is often used with cellular base stations to help overcome multipath problems Five different types of diversity can be used to increase signal reception in the presence of multipath fading: temporal, frequency, spatial, polarization, and angular. The first two types of diversity require changes in hardware

138

One of the most common temporal diversity methods is to use adaptive equalization and RAKE receivers Frequency diversity can be implemented by using two separate radio links on two different channels. Spatial diversity helps overcome the multipath problem by using two identical receive antennas separated by a fixed number of wavelengths

3.6

LINK BUDGET

Link budget planning process helps can be used to estimate range, throughput, and BER.A link budget basically adds all the gains and losses to the transmitter power (in dB) to yield the received power. In order to have adequate signal at the receiver, the power presented to the receiver must be at least as much as the receive sensitivity. The link margin required for reliable operation would be around 20 to 30 dB.

3.7

GAINS Transmitter Power and Antenna Gain: The combination of power output at the antenna and the gain of the antenna itself are legally limited by FCC rules. For Wi-Fi, the maximum power output and antenna gain is limited based on the frequency band used and whether the application is point to point or point to multipoint

3.8 DIFFERENT LOSSES The path loss equation for outdoors can be expressed as Free space path loss = 20 log (d [meters] )+ 20 log (f [MHZ]) + 36.6 dB

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At 2.4 GHz, the formula simplifies to Free space loss = 20 log ( d[meters]) +40 dB This holds as long as there is sufficient amount of area around the Fresnel Zone. Indoors, this formula is more complicated and depends on factors such as building materials, furniture, and occupants. At 2.4 GHz, Indoor path loss (2.4 GHz) = 55 dB + 0.3 dB/d [meters] At 5.7 GHz, Indoor path loss (5.7 GHz) = 63 dB + 0.3 dB/d [meters] Diffraction occurs when the radio path between the transmitter and the receiver is obstructed by a surface that has sharp irregularities or an edge. Coax and Connector Losses Connector losses can be estimated at 0.5 dB per connection. Cable losses are a function of cable type, thickness, and length. The thicker and better built the cable, the lower are the losses and the higher the cost Rain and fog: 2.4 GHz signals may be attenuated by up to 0.05 dB/km by heavy rain . Thick fog produces up to 0.02 dB/km attenuation Trees can be a significant source of path loss. Building material also causes significant loss.

3.9 CONSIDERATIONS IN AP DEPLOYMENT A primary goal of any wireless LAN deployment is to provide reliable signal coverage and expected level of performance (bandwidth capacity) at all desired locations.

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3.9.1 From Coverage Perspective

1) Placement of APs - The locations of access points govern the effective area that they can cover. In open space, antenna of the access point solely decides the radiation pattern. In closed office space, the coverage is shaped up by the presence of RF obstacles such as walls, ceilings, and furniture. 2) AP’s Power The power at which an access point transmits and its receiver sensitivity dictate the size of the cell it can individually cover. From the point of view of increasing the coverage, it is better to use the highest power level. Higher power means larger cell size, and in turn lesser number of access points required to cover a given area. Coverage of a small cell is however better achieved with a low power level, as it reduces the interference with neighboring cells. Also, from capacity point of view, smaller cell size is better, as it reduces the media contention, as well as allows larger fraction of clients to associate at higher data rates. 3) Antenna to Shape Coverage - Coverage shape of an access point needs to be tuned with the use of external antenna. A default omni directional antenna equipped to the access point may not be the best choice for all cases. A hallway or a corridor might be easier to cover with a bi-directional antenna with narrow beam width.

3.9.2 From capacity Perspective

1) Technology Selection - Different technologies can support different data rates. 802.11b can only support a maximum link layer data rate of 11Mbps. 802.11a/g maximum of 54Mbps. As the range at which 802.11a/g support higher rates is much lower, therefore requiring a larger number of access points to provide similar coverage. 2) Minimum Association Rate - The link-layer association data rate between an access point and a client is decided by the signal-to-interference ratio (S/I) between them. At any power level, a fraction of access point coverage (typically closer to access point) receives high S/I ratio, and clients in this area can associate at higher link-layer data rates. Another

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fraction of coverage (farther from access point) is at a low S/I ratio, resulting in lower association rates. Unfortunately, clients associated at lower data rates pull down the effective rates available to everybody else. This happens because every time a lower data rate client needs to transmit/receive a packet, it occupies the channel for longer duration. One way to avoid distant nodes from associating at lower rate is to limit the minimum association rate. This also reduces the effective cell size of the access point, but leaves the interference range of the access point untouched. 3) AP’s Power - The transmission power of access point also indirectly determines the data rate it can support. At higher power, the fraction of coverage with lower S/I ratio becomes higher. This in turn pulls down the effective rates available to even nearby clients, as well as increases the interference range. Also at higher power, the increased cell size of the access point results in larger number of clients being able to associate with it. This increases the media contention reducing per-client available data rate. 4) AP Density - Many times, it is not possible to support the required capacity using a single access point. In such cases, bandwidth aggregation technique can be used where multiple co-located access points associated with the access point operate in different channels and provide the aggregate capacity to the cell. Another possibility is to increase the density of access points in areas with high throughput requirement, and reduce the cell size of individual access points through power control. 5) Client-AP Association - Because of shared nature of the media, per-client data rate goes down with increasing number of clients. The number of clients that an access point allows to associate with itself, therefore, needs to be limited in accordance with the network design.

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CHAPTER 4 RANGE

4.1 FACTORS AFFECTING RANGE There can be several kinds of attenuation that can deteriorate the traveling signal. The table below shows a few.

Table 4.1 Relative attenuation of radio frequency obstacles Obstruction

Degree of Attenuation

Example

Open space

None

Cafeteria, courtyard

Wood

Low

Inner wall, office partition, door, floor

Plaster

Low

Inner wall(old plaster lower than new plaster)

Synthetic materials

Low

Office partition

Cinder block

Low

Inner wall, outer wall

Asbestos

Low

Ceiling

Glass

Low

Non-tinted window

Wire mesh in glass

Medium

Door, partition

Metal tinted glass

Low

Tinted window

Human body

Medium

Large group of people

Water

Medium

Damp wood, aquarium, organic inventory

Bricks

Medium

Inner wall, outer wall, floor

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Marble

Medium

Inner wall, outer wall, floor

Ceramic(metal content or backing)

High

Ceramic tile, ceiling, floor

Paper

High

Roll or stack of paper stock

Concrete

High

Floor, outer wall, support pillar

Bulletproof glass

High

Security booth

Silvering

Very High

Mirror

Metal

Very High

Desk, office partition, reinforced concrete, elevator shaft, filing cabinet, sprinkler system, ventilator

Table 4.1(contd.)

4.2 RF COMPONENTS RF systems complement wired networks by extending them. Few of the RF components are antennas, sensitive receivers, and amplifiers.

4.2.1 Antennas The size of the antenna used depends on the frequency; the higher the frequency, the smaller the antenna. A network interface operating in the 2.4 GHz band has a wavelength of just 12.5 centimeters. Wireless cards all have built-in antennas, but these antennas are, at best, minimally adequate. The antenna type determines its radiation pattern: omni directional, bidirectional, or unidirectional. 802.11 networks typically use omni directional antennas for both ends of the connection .Omni directional antennas are good for covering large areas; bidirectional antennas are particularly good for covering

144

corridors; and unidirectional antennas are the best for setting up point-to-point links between buildings or even different sites. It usually follows that the higher the gain, the narrower the beam. Wireless is a two way system, both the Access Point and Client Device must be communicating at a equal level before a wireless connection can occur.

Figure 4.1 Radiated power of antennas

Access points and wireless routers (as shipped from the manufacturer) have an advantage over laptop and desktop cards because they have a higher output power and therefore have the ability to send a signal further then most laptop and desktop cards. When a higher-gain antenna is installed on a desktop card the output power of that device is now increased closer to the output level of the access point or wireless router therefore equaling the two devices. In some cases, the antennas of both the access point/wireless router and the desktop/laptop card may need to be replaced. This is if the distance you are

145

attempting to achieve is greater than the capabilities of the access point/wireless router when using the (factory) antennas that came with your card.

Figure 4.2 Access point to client device communication

Access Point To Client-side Device (WLAN/PCI Adapter Card)

Output power of client-side devices with factory A high-gain antenna solution extends the range of the antennas are less than that of access points. A signal client-side device, increasing its power closer to that of from an access point will travel farther than that of the access point. (solution dependent on specific situation variables)

the client-side device.

4.2.2 Sensitive Receivers The receiver sensitivity is the lowest level signal that can be decoded by the receiver. Lower the receiver sensitivity, longer the range.

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4.2.3 Amplifiers Smaller noise figures of amplifiers enable the receiver to hear smaller signals and thus provide a greater range. High-power amplifiers (HPAs) are used to boost a signal to the maximum power possible before transmission The transmitter in an 802.11 PC card is necessarily low power because it needs to run off a battery if it is installed in a laptop, but it is possible to install an external amplifier at feed APs. 802.11 devices are limited to 1 watt of power output and 4 watts of effective radiated power (ERP). ERP multiplies the transmitter‘s power output by the gain of the antenna minus the loss in the transmission line. With a 1 watt amplifier, an antenna that provides 8 dB of gain, and 2 dB of transmission line loss, the result is an ERP of 4 watts; the total system gain is 6 dB, which multiplies the transmitter‘s power by a factor of 4.

4.3 SINGLE AP (COVERING LARGE AREA) It's tempting to think that you can put up a high-gain antenna and a power amplifier and cover a huge territory, thus economizing on APs and serving a large number of users at once. This may not be a good idea. The larger the area covered, the more users, APs must serve. A good upper bound to aim for is 20 to 30 users per wireless card per AP. A single AP covering a large territory may look like a good idea, and it may even work well while the number of users remains small. However, if a network is successful, the number of users will grow quickly and the network will soon exceed the AP's capacity. Then it is necessary to install more APs and divide the original cell into several smaller ones and lower the power output at all of the cells.

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4.4 EXTENDING WLAN RANGE WITH REPEATERS Wireless repeaters are an alternative way to extend the range of an existing WLAN instead of adding more access points. Nearly all WLAN repeaters have actually built-in functions of access points. However, the advantage of the stand alone repeaters is that they are generally less expensive. A repeater simply regenerates a network signal in order to extend the range of the existing network infrastructure. A WLAN repeater does not physically connect by wire to any part of the network. Instead, it receives radio signals (802.11 frames) from an access point, end user device, or another repeater and retransmits the frames. This makes it possible for a repeater located in between an access point and distant user to act as a relay for frames traveling back and forth between the user and the access point. As a result, wireless repeaters are an effective solution to overcome signal impairments such as RF attenuation in uncovered areas. The wireless repeater fills holes in coverage; enabling seamless roaming by increasing the range by up to 160%. One downside of wireless repeaters, though, is that they reduce throughput on the WLAN. A repeater must receive and retransmit each frame on the same RF channel, which effectively doubles the number of frames that are sent. This problem compounds when using multiple repeaters because each repeater will duplicate the number of frames sent. Thus repeaters should be used sparingly. In configuring the repeater, after switching the access point to repeater mode, set the SSID of the repeater to match the SSID of the specific (root) access points that the repeater will associate with. Most repeaters will, similar to wireless network cards, automatically associate with the access point with the strongest signal. However, you can designate specific MAC addresses of the preferred and secondary access points as an option. If the repeater cannot connect with the preferred access point, it will try to associate with the next one, and so on.

148

Wireless repeaters are an excellent way to increase the radio range of an existing WLAN, if it's not practical to install an additional access point to fully cover the location.

4.5 THE IMPORTANCE OF UNOBSTRUCTED LINE OF SIGHT IN WIFI Line of sight in microwave includes an area around the path called the Fresnel zone. The Fresnel zone is an elliptical area immediately surrounding the visual path. It varies depending on the length of the signal path and the frequency of the signal. Both antennas should physically see each other. Line-Of-Sight is the Fresnel zone Any obstruction that comes into the Fresnel zone, although not obstructing the visual Line-Of-Sight, may also slow down, hinder and affect your signal. The radio waves may deflect off of those obstructions. This is called Near Line-Of-Sight (nLoS, ). With nLoS situations, data transfer rate may decrease

149

Figure 4.3 Images showing LoS, nLoS, NLoS

An obstruction that cuts across the visual Line-Of-Sight and prohibits an optical visual between the two antennas is considered Non-Line-Of-Sight (NLoS). Any signal, in this case, will be minimal or non-existent.. Tree branches

150

that cross the visual Line- Of-

Sight will move with the wind. This movement will disrupt and have an effect on Wi-fi signal. Multi-polarized, tree-penetrating antennas should be used for these applications. Some obstructions that will decrease the wireless signal are as follows:

Table 4.2 Few obstructions that will decrease the wireless signal Electrical Power Lines

Trees

2.4ghz portable phones

Buildings

Microwaves

Tinted, Metallic Glass

Wire Mesh walls

Other 2.4ghz Wireless Networks

Metal Rooftops

Difference in Elevation from Pt. to Pt

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CHAPTER 5

IMPLEMENTATION OF WMCN IN SMIT

WMCN - Wireless Multimedia Campus Networks are prevalent in all major educational institutions today. With 2000 strong students on the campus there is a huge demand for connectivity. The present wired connectivity with few terminals in ‘Internet Cafe‘ falls much short of ‗Quality Education‘ drive. & Wireless LAN is an answer to it. In this chapter we attempt to clarify three of the core deployment problems - RF propagation modeling, access point positioning and cell dimensioning, and channel allocation.

152

Figure 5.1 Typical deployment

process.

5.1 TYPICAL DEPLOYMENT PROCESS

In the initial phase, the coverage and capacity requirements are collected. The complete coverage area is divided into zones based on bandwidth requirement as well as physical building layout. Next, the number of access points per zone is determined to ensure capacity and to ensure coverage, and the maximum of the two numbers is taken. These access points are then laid out across the coverage zones taking into account the interference due to RF obstacles. The power levels of the access points are set based on the output of the coverage/capacity calculations. Taking cell-to-cell interference and

153

capacity requirements into account, the channel(s) for individual access points are decided. Finally, a physical site survey is carried out to ensure the coverage at various locations, and the deployment plan is altered to handle unexpected interferences. Following subsections enunciate each of these deployment steps A pilot approach should be used where in the first deployment only few common areas such as lobby, conference rooms, are chosen for wireless coverage. This strategy is used to limit the amount of one-time investment and get a better understanding of the user requirements. A campus-wide deployment is again done building-by-building, or department by-department to limit one-time investment.

5.2

MODE AND NETWORK TOPOLOGY

The appropriate mode for campus would be infrastructure mode. In this mode, wireless devices can communicate with each other or with a wired network. In this way, seamless coverage is possible within the subnet. Most WLANs operate in infrastructure mode because they require access to the wired LAN for services like file servers, printers, and Internet access. The mesh topology is a type of network architecture that can be adopted where no centralized base station exists. Each node that is in range of another one can communicate freely as shown in figure 5.2.

154

Figure 5.2 Communication in Mesh topology

Wireless mesh networks are a topology for creating low-cost, high-reliability wireless networks indoors, across a campus, or in a metropolitan area. In mesh network, each wireless node serves as both an AP and a wireless router, creating multiple pathways for the wireless signal. Mesh networks have no single point of failure and thus are selfhealing. A mesh network can be designed to route around line-of-sight obstacles that can interfere with other wireless network topologies. However, a wireless mesh currently requires the use of specialized client software that will provide the routing function and put the radio into ad hoc or infrastructure mode as required. Since some of the rooms in, the

155

massive hostels with 1000 odd inmates, may not get the direct access to APs, Mesh topology would be appropriate.

5.3

FREQUENCY BAND

The 2.4 GHz ISM band has an inherently stronger signal with a longer range and can travel through walls better than the 5 GHz U-NII bands. The 2.4 GHz ISM band has a maximum of three non overlapping 22 MHz channels. However, the U-NII band enables more users to be on the same channel simultaneously. The 5 GHz band has four non overlapping 20 MHz channels in each of the U-NII bands. The 5.15 to 5.25 GHz portion of the U-NII band is intended for indoor, short-range networking devices (200 milliwatt (mW) effective isotropic radiated power (EIRP) limit). Devices operating between 5.25 to 5.35 GHz are intended to provide communications within and between buildings, such as campus-type networks. The 5.725 to 5.825 GHz portion of the U-NII band is intended for community networking communications devices operating over longer distances. Since the implementation is to be carried out by the college itself with the help of students then cheaper, penetrating 2.4 GHz band is suggested. Multimode adapters working on both IEEE 802.11 g & b are available & can be used. Since the campus network may not require very long distance links, with directional antennas, amplifiers desired results could be achieved. Receivers with better receive sensitivity, use of two antennas for diversity at both ends can be thought of.

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5.4

LAYOUT PLANNING

5.4.1 Coverage Planning The first step is to determine the number and placement of access points to ensure coverage. The number of access points required for coverage is estimated by the following simple equation

Where

NAP

is the number of access points required for coverage,

CTotal

is the total area to be covered, and

CAP

is the coverage of a single access point based on maximum power.

5.4.2 Capacity Planning Once the coverage areas are decided upon, the next stage is to determine the bandwidth requirements of each area to approximate the long-term bandwidth available at various locations. Locations with high user density or with users running communication-intensive or interactive applications require better capacity than other locations. For instance, in a retail store/warehouse where associates are using barcode scanners, about 25Kbps per user can serve the purpose. On the other hand, office users accessing word processing documents may need up to 500Kbps of bandwidth. Bandwidth aggregations through multiple overlapping cells or use of densely packed small-sized cells are two ways to provide higher capacity at desired locations.

157

The initial number of access points used to cover an area is the maximum of the one derived in capacity planning stage and in the coverage planning stage. Initially power level is set to the maximum possible. More access points are added if coverage holes are predicted. On the other hand, power level of the access points is reduced if there is too much overlap between the adjacent cells. Some amount of overlap is, however, maintained to ensure continuous coverage to clients

5.4.2.1 Main Block, ‘E’ quadrangle The number of users in various areas around the college is different. During normal classes in classrooms if only the teacher, carrying a laptop, is using WLAN then a single AP is sufficient for many classrooms on one side of a building. But if design is to cater for many students accessing departmental wired resources for presentations, lecture notes during classes then the user density in the classrooms would be very high. They may also be accessing lecture on demand or appearing for on line tests & Quizzes. In such a case connection speed must be high & bandwidth requirement for multimedia applications should be sufficient. We can not have more than 20 to 30 students per AP depending on the application.

5.4.2.2 Academic block ‘C’ quadrangle There are fewer classrooms in this area, but there are labs, administrative office, and conference hall & distance education wing. Each may require a separate AP servicing 20 to 25 clients.

158

5.4.2.3 ‗D’ block Labs in ‗D‘ block should have one AP each .In case of light traffic only one AP should be sufficient to carry entire load Entire Professor‘s block can be served by a single AP.

5.4.2.4 Hostels Hostels are having 3 wings in shape of ‗Y‘. Either one floor can have one AP or a single wing on 3 floors could share one. Actual placement is possible only after extensive site survey & RF signal detection tools. Number of APs is calculated taking worst case scenario.

5.4.2.5 Seminar Hall & Library

These areas require more than 1 AP. Library may be fitted with 2, whereas Seminar Hall with seating capacity of 200 requires more.

5.4.2.6 Corridor Hallway or a corridor is easier to cover with a bi-directional antenna with narrow beam width.

159

This design has been carried out taking into consideration Client-AP Association Because of shared nature of the media, per-client data rate goes down with increasing number of clients. The number of clients that an access point allows to associate with itself, therefore, needs to be limited in accordance with the network design. But if the traffic is light some of the AP may be switched off.

5.5

CHANNEL ASSIGNMENT

The goal of the channel allocation is to reduce interference among cells that are within the interference range of each other. The number of available non-interfering channels depends upon the technology in use - 802.11b and 802.11g can only support 3 nonoverlapping channels, while 802.11a can support up to 12 non-overlapping channels.

Figure 5.3 Channel layout for 3- storied building with classrooms

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CHAPTER 6

SURVEY OF EXISTING WMN IN SMIT

A survey of college WMN has been done. The survey of college has been done because the existing WMN is not effective. It is not able to support the present user requirements. Thus to help in the design of a new WMN system, which is compatible with the existing one, this survey of college wi-fi system has been done.

6.1 FACTORS CONSIDERED DURING THE SURVEY Now during the survey a factor called Fading was kept in mind.

6.1.1 Fading Fading refers to the distortion that a carrier modulated telecommunication signal experiences over certain propagation media. A fading channel is a communication channel that experiences fading. In wireless system, fading is due to multipath propagation and is sometimes referred to as multipath induced fading. The presence of reflectors in the environment surrounding a transmitter and receiver create multipath that a transmitted signal can transverse. As a result the receiver sees the superposition of multiple copies of transmitted signal, each traversing a different path. Each signal copy will experience difference in attenuation, delay and phase shift while traveling from source to the receiver. There are two types of fading depending upon the distance 161

between point a and b. if the distance is small the fading is known as microscopic fading and if the distance is large it is known as macroscopic fading.

6.1.1.1 Microscopic fading The microscopic fading refers to the rapid fluctuations of the received signal space, time and frequency and is caused by the signal scattering off the objects between the transmitter and receiver. Since this fading is a superposition of a large number of scattered components, the components of the received signal can be assumed to be independent zero mean Gaussian process. In absence of Line-Of-Sight (LOS) path between transmitter and receiver the signal envelope becomes Rayleigh distributed. Whereas in presence of LOS path, the signal envelope is Ricean.

6.2.1.2 Macroscopic fading- for outdoor fading measurements The outdoor survey was based on macroscopic fading models. The readings were taken at a larger distance, 10 meters at regular interval and whole of the campus was covered in this way. We know that wavelength λ is given by λ= c/f Where c= 3 X 108 m/s f = 2.4 GHz Solving we get λ as 1/8 meters As we know, for microscopic readings we take readings at small intervals, i.e. 5λ whereas in case of macroscopic readings we take larger intervals i.e.10 λ Microscopic Fading, a = 40 λ Macroscopic Fading, a = 80 λ

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6.2 SOFTWARE USED

6.2.1 Netstumbler Network Stumbler (also known as NetStumbler) is a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards. It runs on Microsoft Windows operating systems from Windows 98 on up to Windows Vista (under compatibility mode). A trimmed-down version called MiniStumbler is available for the handheld Windows CE operating system. It has many uses:

Verify that the network is set up the way you intended. Find locations with poor coverage in the existing WLAN. Detect other networks that might be causing interference with the established network. Detect unauthorized access points in the coverage area. Help aim directional antennas for long-haul WLAN links. The main purpose of netstumbler is to give SNR vs time relationship.

163

Figure 6.1 Graph obtained from Netstumbler

Above is the graph obtained using Netstumbler, showing SNR vs time.

164

Figure 6.2 Screen obtained from Netstumbler

6.3 SURVEY DETAIL

Now as the readings have been taken for two modes, keeping in mind the multipath fading. Since inside the college building microscopic fading exist we have taken the reading of SNR at fixed distances of 8 feets while outside the building

165

macroscopic fading exist, hence we have taken the reading of SNR at fixed distances of 16 feets.

For conducting the survey we installed Netstumbler in a laptop computer and then moved about the entire campus to detect the strength of the wireless network (default). The readings of netstumbler gave us the value of SNR and signal strength at various locations Initially we had smitwifi6 and smitwifi2 in the college. We took the survey for whole of the campus spanning the area(s) under these two networks. But due to some problem which occurred in the wi-fi set up, the wireless networks were changed to default networks, with smitwifi6 serving a limited area inside the college building. For visual aid, a map of campus was divided into 5 categories depending on the signal strength. The figure (6.3) shows the campus layout in which the campus has been divided in 5 zones, each zone having its own range of signal strength, i.e

Table 6.1 Categorization of signal with respect to colours

Colour

Signal Strength(dbm)

Remarks

Blue

-40 to -50

Excellent

Pink

-51 to -60

Good

Green

-61 to -70

Average

Orange

-71 to -80

Poor

Black

-81 to -90

No signal

Figure 6.3 Signal strength distribution across the college campus

166

This clearly shows that the area(s) having blue colour have excellent signal strength ,i.e., in the range -40 to -50 dbm, the area(s) with pink colour are having signal in the range of -51 to -60 dbm, that with green colour have signal strength in the range of -61 to -70 dbm and lastly orange implies poor signal strength. The blackened area(s) have no wi-fi access.

We observed that SMIT WiFi6 provides network only to the D corridor. While the access point above the C Quad provide network to the girls‘ hostel, the access point above E Quad provides network to the boys‘ hostel. We also observed that signal strength is not uniform throughout the hostels. Blocks of the hostel facing the access points have good

167

Table 6.2 Readings showing signal wrt distance

Network

Range(a)

Range (mt.)

SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6 SMITWIFI6

a=0 2a 3a 4a 5a 6a 7a 8a 9a 10a

5 10 15 20 25 30 35 40 45 50

Range (in lambda) 40 80 120 160 200 240 280 320 360 400

Signal(dBm) -39 -44 -39 -39 -39 -39 -39 -39 -39 -39

Figure (6.4), below shows the relationship between signal (in dbm) and range (in lambda and mts). The yellow coloured bars represent signal strength with respect to time, the red coloured bars represent range in lambda and the blue coloured bars represent range in metres. signal strength, whereas those blocks that are not facing the antenna are having low signal strength or none at all. Below is table (6.2) showing the signal in dbm with respect to the distance. Several other readings were also taken but as an example, only the table (6.2) has been shown.

Figure 6.4 Graph plotted in excel for Signal (dbm) vs Range (mts & lambda) 168

Figure 6.5 Graph plotted in Net stumbler for SNR vs Time

169

Graph(6.5) was obtained on taking the readings using Netstumbler, as shown below. Here the x-axis represents the time and y-axis shows the SNR. Netstumbler can also be used to show relation between the distance and SNR. Thus, on the basis of above survey information, a design of a WMN for college has been done. This will help improve the existing WMN in several manners listed below: This will increase the speed of internet, thus will accelerate the internet accessing as well as downloading speed. More number of users can be accommodated at the same time. This will improve the Wi-fi signal strength.

CHAPTER 7

170

DESIGN OF WMN IN SMIT

7.1 INTRODUCTION OF WIRELESS MESH NETWORK As various wireless networks evolve into the next generation to provide better services, a key technology, wireless mesh networks (WMNs), has emerged recently. In WMNs, nodes are comprised of mesh routers and mesh clients. Each node operates not only as a host but also as a router, forwarding packets on behalf of other nodes that may not be within direct wireless transmission range of their destinations. A WMN is dynamically self-organized and self-configured, with the nodes in the network automatically establishing and maintaining mesh connectivity among themselves (creating, in effect, an ad hoc network). This feature brings many advantages to WMNs such as low up-front cost, easy network maintenance, Robustness, and reliable service coverage. Conventional nodes (e.g., desktops, laptops, PDAs, Pocket PCs, phones, etc.) equipped with wireless network interface cards (NICs) can connect directly to wireless mesh routers. Customers without wireless NICs can access WMNs by connecting to wireless mesh routers through, for example, Ethernet. Thus, WMNs will greatly help the users to be always-on-line anywhere anytime Moreover, the gateway/bridge functionalities in mesh routers enable the integration of WMNs with various existing wireless networks such as cellular, wireless sensor, wireless-fidelity (Wi-fi) worldwide inter-operability for microwave access (WiMAX) , WiMedia networks Consequently, through an integrated WMN, the users of existing network can be provided with otherwise impossible services of these networks WMN is a promising wireless technology for numerous applications , e.g., broadband home networking, community and neighborhood networks, enterprise networking, building automation, etc. It is gaining significant attention as a possible way for cash strapped Internet service providers (ISPs), carriers, and others to roll out robust and reliable wireless broadband service access in a way that needs minimal up-front investments With the capability of self-organization and self configuration, 171

WMNs can be deployed incrementally, one node at a time, as needed. As more nodes are installed, the reliability and connectivity for the users increase accordingly.

7.2 CHARACTERISTICS OF WMN The characteristics of WMNs are explained as follows:

• Multi-hop wireless network: An objective to develop WMNs is to extend the coverage range of current wireless networks without sacrificing the channel capacity. Another objective is to provide non-line-of-sight (NLOS) connectivity among the users without direct line-of-sight (LOS) links. To meet these requirements, the mesh-style multihopping is indispensable, which achieves higher throughput without sacrificing effective radio range via shorter link distances, less interference between the nodes, and more efficient frequency re-use. • Support for ad hoc networking, and capability of self-forming, self-healing, and selforganization WMNs enhance network performance, because of flexible network architecture, easy deployment and configuration, fault tolerance, and mesh connectivity, i.e., multipoint-to-multipoint communications. Due to these features, WMNs have low upfront investment requirement, and the network can grow gradually as needed. • Mobility dependence on the type of mesh nodes: Mesh routers usually have minimal mobility, while mesh clients can be stationary or mobile nodes. • Multiple types of network access: In WMNs, both backhaul access to the Internet and peer to-peer (P2P) communications are supported. In addition, the integration of WMNs with other wireless networks and providing services to end-users of these networks can be accomplished through WMNs.

172

• Dependence of power-consumption constraints on the type of mesh nodes: Mesh routers usually do not have strict constraints on power consumption. However, mesh clients may require power efficient protocols. As an example, a mesh-capable sensor requires its communication protocols to be power efficient. Thus, the MAC or routing protocols optimized for mesh routers may not be appropriate for mesh clients such as sensors, because power efficiency is the primary concern for wireless sensor networks. • Compatibility and interoperability with existing wireless networks: For example, WMNs built based on IEEE 802.11 technologies must be compatible with IEEE 802.11 standards in the sense of supporting both mesh capable and conventional Wi-fi clients.

7.3 CRITICAL FACTORS INFLUENCING NETWORK PERFORMANCE

Before a network is designed, deployed, and operated, factors that critically influence its performance need to be considered. For WMNs, the critical factors are summarized as follows: • Radio techniques: Driven by the rapid progress of semiconductor, RF technologies, and communication theory, wireless radios have undergone a significant revolution. Currently many approaches have been proposed to increase capacity and flexibility of wireless systems. Typical examples include directional and smart antennas, MIMO systems, and multi-radio/multi-channel systems. To date, MIMO has become one of the key technologies for IEEE 802.11n, the high speed extension of Wi-fi. Multi-radio chipsets and their development platforms are available on the market. To further improve the performance of a wireless radio and control by higher layer protocols, more advanced

173

radio technologies such as reconfigurable radios, frequency agile/cognitive radios, and even software radios have been used in wireless communication. • Scalability: Multi-hop communication is common in WMNs. For multi-hop networking, it is well known that communication protocols suffer from scalability issues, i.e., when the size of network increases, the network performance degrades significantly. Routing protocols may not be able to find a reliable routing path, transport protocols may loose connections, and MAC protocols may experience significant throughput reduction. As a typical example, current IEEE 802.11 MAC protocol and its derivatives cannot achieve a reasonable throughput as the number of hops increases to 4 or higher (for 802.11b, the TCP throughput is lower than 1.0 Mbps). The reason for low scalability is that the end-toend reliability sharply drops as the scale of the network increases. In WMNs, due to its ad hoc architecture, the centralized multiple access schemes such as TDMA and CDMA are difficult to implement due to their complexities and a general requirement on timing synchronization for TDMA (and code management for CDMA). When a distributed multi-hop network is considered, accurate timing synchronization within the global network is difficult to achieve. Thus, distributed multiple access schemes such as CSMA/ CA are more favorable. However, CSMA/CA has very low frequency spatial-reuse efficiency, which significantly limits the scalability of CSMA/CA-based multi-hop networks. To improve the scalability of WMNs, designing a hybrid multiple access scheme with CSMA/CA and TDMA or CDMA is an interesting and challenging research issue. • Mesh connectivity: Many advantages of WMNs originate from mesh connectivity which is a critical requirement on protocol design, especially for MAC and routing protocols. Network self organization and topology control algorithms are generally needed. Topology-aware MAC and routing protocols can significantly improve the performance of WMNs • Broadband and QoS: Different from other ad hoc networks, most applications of WMNs are broadband services with various QoS requirements. Thus, in addition to end174

to-end transmission delay and fairness, more performance metrics such as delay jitter, aggregate and per node throughput, and packet loss ratios, must be considered by communication protocols. • Compatibility and inter-operability: It is a desired feature for WMNs to support network access for both conventional and mesh clients. Thus, WMNs need to be backward compatible with conventional client nodes; otherwise, the motivation of deploying WMNs will be significantly compromised. Integration of WMNs with other wireless networks requires certain mesh routers to have the capability of interoperation among heterogeneous wireless networks. • Security: Without a convincing security solution, WMNs will not be able to succeed due to lack of incentives by customers to subscribe to reliable services. Although many security schemes have been proposed for wireless LANs, they are still not ready for WMNs. For instance, there is no centralized trusted authority to distribute a public key in a WMN due to the distributed system architecture. The existing security schemes proposed for ad hoc networks can be adopted for WMNs, but several issues exist: – Most security solutions for ad hoc networks are still not mature enough to be practically implemented. – The network architecture of WMNs is different from a conventional ad hoc network, which causes differences in security mechanisms. As a consequence, new security schemes ranging from encryption algorithms to security key distribution, secure MAC and routing protocols, intrusion detection, and security monitoring need to be developed. • Ease of use: Protocols must be designed to enable the network to be as autonomous as possible, in the sense of power management, self organization, dynamic topology control, robust to temporary link failure, and fast network subscription/ user-authentication procedure. In addition, network management tools need to be developed to efficiently maintain the operation, monitor the performance, and configure the parameters of WMNs. These tools together with the autonomous mechanisms in protocols will enable rapid deployment of WMNs. 175

7.4 DESCRIPTION OF EXISTING WMN

The college has a total of 550 wi-fi subscribers. Thus the existing college WMN (Wireless Mesh Network) consists of 5 antennas. Each antenna has different characteristics as per the need. All the 5 antennas with their locations are mentioned below.

Table 7.1 Description of existing antennas Manufacturer’s name Hyperlink Sector Antenna Complex Sector Antenna Senao Sector Antenna Senao Omni Antenna

No. of antenna 1

Antenna angle 90°

Gain

Location

16dbi

1

90°

16dbi

1 1

120°

16dbi 16dbi

Above E block Above C block ETP On the Mess building Inside D block

---Omni directional antenna

1

----

16dbi

There are 4 routers in the college as follows:

Table 7.2 Description of existing routers Manufacturer’s name

No. of access points

176

Power per access point

Senao Access Point/Router

3

400MW

Senao Access Point/Router

1

200MW

Figure 7.1 Area to be covered

As seen in the figure (7.1), the antennas above C quadrangle and E quadrangle are symmetrical in nature. The antenna above C quad, which is a SECTORIAL antenna provides signal to the girls‘ hostel. Similarly the antenna above E quad (also a sectorial antenna) provides signal to the old boys‘ hostel. The OMNI directional antenna on the mess provides signal to some blocks of girls‘ hostel and some blocks of boys‘ hostel namely K & J blocks and ------ blocks respectively. The sectorial antenna on ETP is installed to provide signal to the ---- blocks of the boys‘ hostel. 177

Another antenna (not seen in the figure) is placed inside D block and is basically for testing purposes. It is an omni directional antenna.

7.5 PROBLEMS IN THE EXISTING WMN The existing network system does not support the user requirements. Some of the problems are mentioned below:

Data rate is not high, thus the network speed is slow. This can be a major problem when downloading data, audio or video. The network coverage is not good throughout the campus. There are only few areas where the signal strength is strong; otherwise the signal strength is weak at maximum areas across the campus. The existing network system is not able to support many users.

Thus, a network layout has been designed that will be compatible to the existing WMN and will help enhance the signal strength.

CHAPTER 8

DESIGNING WMN IN SMIT

178

8.1 FACTORS WHILE DESIGNING THE LAYOUT

8.1.1. Antenna type There are a variety of antennas in the market. But we should choose the one that has the required properties and that can serve the purpose. Few of the antennas with their properties are mentioned below:

8.1.1.1 Horn antenna A horn antenna may be regarded as a flared out or opened out waveguide. A waveguide is capable of radiating radiations into open space provided the same is excited at one end and opened at the other end.

Different types of horn antenna are available:

Sectorial horn antenna: If flaring is done only in one direction, then sectorial horn is produced. Now flaring in the direction of Electric vector and Magnetic vector, the sectorial E-plane horn and sectorial H-plane horn are obtained.

Pyramidal horn antenna: If flaring is done along both the walls of the Rectangular waveguide, then pyramidal horn is obtained.

Conical horn antenna: By flaring the walls of a circular waveguide, a Conical horn is formed.

USES: These are used at microwave frequencies under the condition that power gain needed is moderate.

179

For higher power gain, since the horn dimensions are large, so the other antenna like lens and parabolic reflector etc. are preferred rather than horn.

8.1.1.2 Helical antennas Helical antenna is another basic type of radiator and perhaps it is the simplest antenna to provide circularly polarized waves or nearly so which are used in Extraterrestrial Communications in which satellite relays etc. are involved. It is broad band VHF and UHF antenna to provide polarization characteristics.

USES: Single or array of helical antenna is used to receive or transmit the VHF signals through ionosphere. The wide bandwidth, simplicity, highest directivity and circular polarization of the helical beam antenna have made it indispensable for space communication applications.

8.1.1.3 Microwave antennas

UHF and SHF bands are respectively 300-3000 MHz and 3000-30000 MHz but the microwave region starts from 1000 MHz and extends upto 100000 MHz. The corresponding wavelength is in cms, 10-1 cm and less. Thus the antenna that uses this spectrum for transmitting and receiving is called microwave antenna. These antennas tend to be directive i.e. high gain and narrow beam width in both horizontal and vertical planes.

180

The most important practical antennas in microwave frequency range are:

Parabolic reflector or Paraboloid or Microwave dish Lens antennas Horn antennas

The last one has already been discussed before, so first two will be discussed now.

Parabolic reflector: Parabolic reflectors are based o geometric optical principles. A parabola may be defined as the locus of a point which moves in such a way that its distance from a fixed point plus its distance from a straight line is constant. Focusing or beam formation action of parabolic reflector can be understood by considering a source of radiation at the focus. All the waves originating from the focus will be reflected parallel to the parabolic axis. This implies that all the waves thus, reaching at the aperture plane are in phase. Since all the waves are in phase, so a very strong and concentrated beam of radiation is there along the parabolic axis.

Lens antennas: These are also based on the geometric optical principles. Their feed method is not by coaxial but by optical method. Lens antenna works at a bit higher frequency. The range for lens antenna starts at 1000 MHz but its greatest use is at or above 3000 MHz. At lower frequencies, lens antenna becomes bulky and heavy. They act as just the glass lens used in optics.

8.1.1.4 Omni directional antenna An omni directional antenna is an antenna system which radiates power uniformly in one plane with a directive pattern shape in a perpendicular plane. Antennas provide a 360 degree horizontal radiation pattern. These are used when coverage is required in all 181

directions (horizontally) from the antenna with varying degrees of vertical coverage. A low gain omni antenna provides a perfect coverage for an indoor environment. It covers more area near the AP or a wireless device in order to increase the probability of receiving the signal in a multipath environment.

8.1.1.5 Sectorial antenna A sectorial loop antenna comprising: a ground plane; a pie-slice shaped sector having a point positioned adjacent to the ground plane; a first arch coupled to the ground plane and one side of the sector opposite to the point; a second arch coupled to the ground plane and an opposite side of the sector opposite to the point; and a feed electrically coupled to the point of the sector and electrically isolated from the ground plane. the sector has an arc angle of about 90° or 120°.

8.1.2 Area to be covered The selection of antenna also depends on the area to be covered. As seen in fig(7.1) , the area to be covered is large and as seen the existing WMN is unable to support its requirements, thus each antenna selected should be such that it covers up the area for which it is installed.

8.1.3 Range of antenna The selected antenna should have the range so as to cover the area for which it is installed. 8.1.4 Gain of antenna The gain of an antenna is the basic property which is frequently used as the figure of merit. The ability of an antenna or antenna system to concentrate the radiated power in a 182

given direction or conversely to absorb effectively the incident power from that direction is specified by gain. Thus the antenna selected should have high gain.

8.1.5 Number of antennas The number of antennas to be installed is based on the area to be covered. As the area to be covered is large, thus the number of antennas to be installed will also be large. Since it has already been seen that the existing number of antennas do not serve the purpose, thus the number of antennas in the new layout should exceed the already existing number of antennas.

8.1.6 Interference problem The location of antennas should be decided in a manner so that they do not interfere with the existing antenna signal pattern.

8.1.7 Height of antenna Since wavelengths are large at low and medium frequencies and hence it becomes difficult to use an antenna of resonant length. The actual antenna length should be atleast quarter wavelength above the ground to make it resonant. Electrically short antennas, i.e., antennas having length or height less than one tenth of the wavelength, are generally used as vertically grounded antennas and grounded antennas are usually having low radiation efficiency.

8.1.8 Antenna efficiency

183

The antenna efficiency represents the fraction of total energy supplied to the antenna which is converted into electromagnetic waves. Mathematically, efficiency is defined as the ratio of power radiated to the total input power supplied to the antenna. The desirable condition is to have high efficiency.

8.2 LAYOUT

As seen that there are few flaws in the existing WMN system, thus a new WMN system has been designed which is compatible with the existing one and also will be able to remove the problems of the old system to certain extent.

Figure (8.1) shows a layout of the design that has been proposed. There are a total of 12 antennas, involving the existing one and the proposed one. A square symbolizes a new antenna, whereas a circle symbolizes the existing one. Thus there are a total of 8 new antennas. As already been discussed, selection of the right type of antenna is essential. Here we have used sectorial antenna mostly and omni directional antenna at some places. For properties refer to page. In the figure (8.1), the proposed antennas have been placed at different places according to the need. Infact there properties have also been varied to meet the requirements. Antennas as per there placement are listed below. Starting from the guest house, a 120° sectorial antenna, to provide signal to the Boys‘ hostel G-block and the new girls‘ hostel (which is under construction).

An omni directional antenna on dispensary to provide signal inside the classes held there. A 90° sectorial antenna on the playground for the D and E blocks of the boys‘ hostel.

184

Since the antenna on ETP is not very effective, thus another 120° sectorial antenna for the E, F, G, H blocks of boys‘ hostel on the lights of basketball court. Similarly a 90° sectorial antenna on I-block for A block of boys‘ hostel. Another 90° sectorial antenna on R-block for K-block and some parts of L-block of girls‘ hostel. A 90° sectorial antenna on Power station, so as to provide signal to the O- block of girls‘ hostel

Figure 8.1 Contour mapping for signal variation

185

Contour mapping for the antennas have been done and shown in figure (8.1). The demarcation lines that show the antenna‘s angle and its area of coverage have also been shown in the figure. The contour mapping has been done with the help of software from Hughes. This particular software takes few parameters as input and gives the value of SNR as output. Figure (8.2),(8.3),(8.4),(8.5) show the user interface of the Hughes software. The inputs used are:

Frequency of operation Range (i.e. target distance) Antenna diameter Transmitter power at the transmitter side Noise bandwidth at the receiver side Figure 8.2 User interface of software by Hughes

186

Figure 8.3 User interface

Figure 8.4 User interface

187

Figure 8.5 Screen showing the inputs and the outputs

The values used for above mentioned inputs were: Frequency: 2.4GHz Antenna diameter: 2.5 cm for omni directional antenna 18 cm for sectorial antenna Transmitter power: 0 db Noise bandwidth: 20MHz Range: It depends on the target distance starting from 10mts. Few formulas that have been used are: Effective radiated power: Gain + Transmitter power Signal at transmitter: Effective radiated power – Free space attenuation Signal to noise ratio at receiver: signal at transmitter – Effective noise input Thus SNR can be calculated using the above formulae. 188

Table (8.1) shows the colour coding for signal strength variation in the map.

Table 8.1 Colour coding for signal strength variation Colour Red Blue Green Yellow Pink Orange Dark Blue Purple

SNR 20-25 26-30 31-35 36-40 41-45 46-50 51-55 56-60

Thus the above table shows that the area under purple coloured contour has the best signal strength, followed by the dark blue one. Also seen in the map, is the confined area for every antenna demarcated by lines (depending on the antenna angle).

8.2 CONCLUSION Thus a design has been made which can improve the signal quality in college campus. After the design we have done an experiment in which we have used an antenna made out of a can, called cantenna. The details related to cantenna are discussed in the next chapter.

189

CHAPTER 9

CANTENNA

9.1 INTRODUCTION A ―cantenna‖ is a common name applied to antennas usually made from cans. They basically fall into a category called ―microwave waveguide‖ types of antennas used for 802.11b, ‗b+‘, and ‗g‘ wireless Ethernet networks. Since both ‗b‘ and ‗g‘ use the same frequency

range,

this

antenna

will

work

for

both.

These antennas can be used for high-gain, high-directional use for WarDriving, Nanny Cam driving, security assessments and/or any other type application of the 2.4 GHz ISM RF spectrum. They work well in extending the range of your existing WLAN (Wireless LAN), or in sharing network resources or Internet connectivity to other locations. They are not omni-directional however the cantenna will work well in finding weaker signals. They give better and more focused signal for wireless networks. They can be 190

used on both a wireless Access Points (AP‘s) and a wireless client cards. They can also be used to gain signal strength, replacing the factory antenna, or to direct signal to a more focused area. Another reason to use a directional antenna such as this one is security. Using a focused antenna prevents signal from being widely dispersed thus making it difficult to be hacked. Cantennas are portable and can be used to share resources on network or high-speed Internet connection with others. Unlike commercial high gain-type antennas, these are highly portable and can easily be taken on the road and they are comparatively cheaper The cantenna III represents the third generation design of the cantenna. Changes over the previous designs include a custom-made, lightweight (but very durable) can that is a fullwavelength design for 802.11b. Gain has increased to approximately 20 dB (depending on

conditions

and

your

environment).

Many of the newer wireless video hardware work in the 2.4 GHz radio spectrum, such as the X10 cams. Because these antennas are tuned for this frequency range, they are also able to work with wireless video hardware. They have been used by security and lawenforcement officials in remote wireless video surveillance. Only a few models offer WEP encryption at this time, so most signals are transmitted in the ‗clear‘. They can be mounted on a permanent outdoor mount and are also portable enough to be taken on the road. It can also be used inside the access point to help indoor coverage, or direct

the

signal

to

a

specific

area.

Another thing to consider if permanently mounting outdoors is you may want to invest in lightning protection. Lightning and static discharges can damage the equipment it is connected

to,

along

with

other

devices.

They work best in LOS (Line-of-Sight) environments, in which, with careful aiming and alignment, we may be able to get several miles.

Rule of thumb is, glass will attenuate the signal approximately 1-2 dB (beware of 191

‗metalized‘ glass, or glass with metal wire mesh). Breeze-block, drywall or wooden walls will drop the signal about 4-6 dB per wall. Brick, metal or stone walls will result in higher losses. In the UK, many houses are having walls that contain metal wire mesh in them. Also, some houses in severe-weather locations can have steel reinforcements in their walls. This presents a real problem for high-frequency radio waves and should be taken into consideration when planning a wireless deployment. Trees and foliage will also interfere with these frequencies.

A simple model of a cantenna is shown in the figure below

Figure 9.1 Simple cantenna

192

The figure above is a model of the cantenna constructed by us. It consists of a

1. Driver Element

2. Reflector

3. Pigtail arrangement

193

4. Connector

5. Router

9.2 INTERFERENCE, HEALTH AND SECURITY CONCERNS The antenna design constructed by us is extremely experimental. Its use

could cause

interference in near-band frequencies that are commonly used in things such as portable wireless (not cellular) phones that people may have in their homes near us. There are all kinds of wireless devices that operate around the same band as 802.11b, and these are potentially disrupted by use of the equipment described here. 2.4 GHz also happens to be the resonant frequency of water. This is even the working principle of a microwave oven. The energy of an 802.11b device is the same kind of energy that cooks food in the oven, but on a much smaller scale. This is important considering that we as humans are 98% made of water. Hence exposure to even as little as a 1/4 watt amplified with a 14db antenna, such as described here, could lead to severe vision problems and possibly other health issues. Wireless is not very secure though. It does not require tapping a physical connection to hack the transmitted signal. In case of wireless the data is freely flowing through the air, thus an unwanted person can easily intercept it. Thus it is necessary to encrypt the data before sending it though a wireless medium.

2.1 SIMPLE ANTENNA THEORY

194

9.3.1 Basic Concepts The process of conveying information or intelligence or message from one place to another is known as communication. When electromagnetic waves or radio waves are utilized for communication purpose, then it is called as radio or wireless communication. Electromagnetic waves consist of electrical and magnetic fields always perpendicular to each other

which travel in perpendicular direction to travel wave. Thus wireless

communication can be defined as ―the interchange of intelligence, signals, symbols between two or more places employing electromagnetic waves as medium of transmission. Basic requirements of any system of wireless communication system are Transmitter

Transmitting antenna

Receiving antenna

Receiver

Receiving antenna

A simple block diagram of a wireless network is shown below. It consists of a microphone or a source, which generates the signal to be transmitted. This signal is generally encrypted so that it cannot be detected.

Figure 9.2 Simple block diagram of a wireless system

195

The signal thus generated is sent to a transmitter where it is converted from analog to digital form and then modulated according to the requirement. The modulated signal is then transmitted in free space via a transmitting antenna. At the receiving end a receiving antenna receives the EM waves. The signal is then sent to the receiver where it is demodulated and is converted from digital to analog form. The analog signal is then sent to the headset (any output device).

9.3.2 Modulation Modulation may be defined as a process by which any characteristic of a wave is varied as a function of the instantaneous value of another wave. The first wave, which is normally a single high frequency wave, is known as carrier wave. The second wave (normally audio) is known as modulating wave and the resultant wave is known as modulated wave. 196

When the message signal (audio) is directly transmitted, possibly after amplification, then it is known as base band transmission as in case of telegraphy, telephony (except radio telegraphy) and public amplifier system in an auditorium. Thus it is seen that baseband is the part of the frequency spectrum that is covered by the message signal. Since the high frequency electromagnetic waves in free space travel with less attenuation and can be received at a large distance from the source that is why information is sent over such ―carrier‖ by using the modulating signal to vary in accordance with some property or the other property of the carrier. This process of varying some characteristic of the carrier by the message signal (modulating signal) is given the name modulation. The on-off method of wireless telegraphy corresponding dash and dot of the morse code is a crude form of amplitude modulation. In wireless telegraphy, the carrier amplitude is modulated from full on to full off in accordance with the information signal. Due to availability of sinusoidal carrier wave now, frequency, phase and various types of amplitude modulations are used. If the carriers assume the shape the shape of a train of rectangular pulses, a fourth type of modulation is possible known as Pulse Code Modulation (PCM). Pulse Code Modulation is the basis of all kind of digital modulation techniques in use at present. Mathematically a sine wave is represented as

e = Em sin (wt + q) Where e = instantaneous value of sine wave called carrier wave. Em = maximum amplitude w = angular velocity or angular frequency q= phase angle

Figure 9.3 A sinusoidal wave

197

Variation of any of these parameters i.e. amplitude, frequency and phase angle of the carrier in accordance with the modulating signal, will give rise to amplitude, phase modulations respectively. It would also not be out of way to mention about the various frequency bands involved for various kind of modulation. The frequency of carrier wave is much higher than the frequency of modulating signal (i.e. audio signals). The audio signals from a microphone contain frequencies upto 15 kHz maximum where as the carrier frequencies lie 150 kHz to 285 kHz for long wave band, 550 kHz to 1600 kHz for medium wave band and 6 MHz to 25 MHz for short wave bands. Video signal for television have frequencies upto a few frequencies upto a few MHz say 5 to 6 MHz and a carrier of very high frequency (VHF) is used. This is in frequency range of 30 MHz or higher. In some T.V. transmission the idea of subcarrier is used i.e. carrier of 5.5 MHz is modulated by an audio signal. The resulting signal is then made a part of an information signal, which also has video information and is transmitted at a carrier frequency of say 197 MHz. The transmission covers a region in the frequency spectrum, which is situated around the carrier frequency and is atleast as wide as highest frequency of the modulating signal. The width infact depends upon the type of modulation used. Hence, the required bandwidth is an important criterion governing the choice of modulation method.

9.3.3 Why modulation

198

For transmission of message over long distances in the radio channel, there are two alternatives. The first is either the signal is modulated (i.e. modulating signal) itself is transmitted or to use an unmodulated carrier. Let us first is the impossibility of transmitting the signal itself. There are several difficulties in propagation of electromagnetic waves at frequencies corresponding to audio spectrum i.e. between 20 Hz to 20 KHz. The greatest is that for effective transmission and reception, the transmitting and receiving antennas should have heights comparable to wavelengths used. For,

λ = 300,000,000 / f (Hz) Or, λ = 300/ f (MHz) meters Or, λ/4 =75/f (MHz) meters = 75 m,

If f =1 MHz And λ/4 = 75 / 15 * 10(-3) m = 5000m If f =15 kHz = 15 * 10(-3) MHz

Thus, it is seen from above calculations that for frequency of 1 MHz and 15 kHz, the wavelength corresponds to 75m and 5000m for a quarter wavelength operations. Obviously, it would be unthinkable to have a quarter wavelength antenna of this size. Still another argument against transmitting signal frequency directly i.e. all the audio signals are concentrated within the range of 20 Hz to 20 KHz and all the signals from different sources would be so mixed that it is difficult to separate them. As such in any city, broadcasting stations itself alone will be blanketing the air and yet they represent a small proportion of the total transmitter in operation.

199

Therefore, in order to separate the various signals, it could be essential to translate them all to different portions of electromagnetic spectrum and each must be given its own ―pigeonhole‖.

9.4 WORKING PRINCIPLE

In case of a cantenna the signal source is connected to the driver element through a pigtail arrangement. Now the driver element in the cantenna radiates the input signal. Generally a copper rod is used as the driver element. The length of which is nearly half the radius of the can used. The can acts as the reflector. The bottom of the can is metal and should have electrical contact with the sides of the can. The longer the reflector, the more directional and less omni the antenna will be. . The can portion of the antenna is called the reflector because it reflects the signal back out of the can. Hence the can focuses the signal radiated by the driving element. Hence the signal sent in free space is highly directional (but it is not omni directional). Cantenna body is covered with paint or wrinkle black powder to avoid the leakage of the radiated signal.

9.4.1 Apparatus required

Can Copper rod Router N- type female connector Co-axial wire Soldering rod Drilling machine

200

9.4.2

Softwares used:

Net stumbler v 0.4.0 Tomato Firmware

9.4.3 Construction:

For constructing the cantenna firstly we acquired the apparatus required. Then we followed the steps as described below:

1. We acquired tin cans of diameter around 10 cm diameter.

Figure 9.4 Step 1

2. Then we cut the can open and washed it properly.

201

Figure 9.5 Step 2

3. Then we acquired an n-type connector and copper rod for constructing the driver element.

Figure 9.6 Step 3

202

4. Then we soldered the copper wire and n-type female connector to form the driver element.

Figure 9.7 Step 4

203

5. Then we drilled a hole in the can to fit the driver element. The hole was drilled at a height of 4.4 cm from the bottom of the can.

Figure 9.8 Step 5

204

6. Then we fitted the driver element in the can.

205

Figure 9.9 Step 6

7. Then we connected the other side of n-type connector to a wire to form the pigtail arrangement.

Figure 9.10 Step 7

206

8. Finally after assembling the parts of the antenna we obtained the cantenna.

Figure 9.11 Final Cantenna

207

9.4.4 Procedure 1. We removed the antennas of the router. Since our router has two antennas and we had only one cantenna we disconnected one of the router antenna. 2. We connected the cantenna to the functional antenna of the router. 3. We connected power supply to the router. The router generates the signal, which is then radiated by the cantenna. 4. We then used softwares like Net stumbler and tomato to detect the signal strength received by the cantenna at an interval of 1 foot. 5. Then we repeated the same experiment without the cantenna. 6. Then we divided the signal to noise ratio with cantenna and signal to noise ratio without cantenna to obtain the gain achieved by the cantenna. 7. Then we varied various other perimeters like length, angle etc to obtain maximum gain.

208

Figure 9.12 Net stumbler in use

Figure 9.13 Cantenna signal being detected by laptop.

209

Figure 9.14 Apparatus for the experiment.

210

After setting up the apparatus we observed that the maximum signal strength is obtained when the can is placed horizontally with respect to the receiver. The readings thus obtained are tabulated as under.

Dist (ft) 1 2 3 4 5

Table 9.1 Readings of original cantenna SNR with cantenna SNR without cantenna (db) (db) 39 28 26 22 18 18 16 14 14 13 211

Gain 1.4 1.2 1 1.1 1.09

6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

12 15 15 11 11 12 12 12 8 10 10 11 9 9 11 12 12 11 10 9 10 9 9 9 9 9 9 9 9 9 9 9 8 8 8 8 8 8 8 8 8 8 8 8 8

10 13 12 10 15 10 12 10 12 10 10 10 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 8 8 8 8 8 8 8 8 8 8 8 8 8

1.2 1.1 1.2 1.1 .9 1.2 1 1.2 .66 1 1 1.1 1 1 1.2 1.3 1.3 1.2 1.1 1 1.1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 212

51 8 52 8 53 8 54 8 55 8 56 8 57 8 58 8 59 8 60 8 Table 9.1(contd.)

8 8 8 8 8 8 8 8 8 8

1 1 1 1 1 1 1 1 1 1

Figure 9.15 Signal strength obtained with cantenna

Figure 9.16 Signal strength received without cantenna

213

Table 9.2 Readings of double can cantenna Dist (ft) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

RSI -51 -56 -59 -62 -60 -60 -63 -65 -60 -69 -70 -70 -72 -69 -72 -76

Noise -96 -99 -93 -91 -97 -90 -96 -99 -96 -94 -94 -94 -96 -94 -92 -90

Quality (%) 45 43 34 29 37 30 33 34 36 35 24 24 24 24 19 14 214

17 -70 18 -72 19 -72 20 -70 21 -73 Table 9.2(contd.)

-96 -97 -93 -94 -93

26 25 21 24 20

Table 9.3 Readings without cantenna Dist (ft) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

RSI -54 -59 -63 -63 -65 -66 -69 -65 -65 -70 -73 -73 -73 -73 -75 -77 -79 -80 -80 -80 -82

Noise -96 -93 -94 -96 -94 -96 -96 -94 -94 -94 -96 -96 -93 -90 -94 -99 -98 -95 -92 -94 -93

Quality (%) 42 34 32 33 29 30 27 29 29 24 23 23 20 17 19 18 19 15 12 14 11

9.5 OBSERVATIONS

215

We observed that the cantenna is most effective when it is placed in horizontal direction with respect to the receiver. We also noticed that when we used a single can antenna our range was limited to around 1 foot. We noticed as the length of the can or the reflector is incremented the range of the cantenna increases. Hence we used a double can cantenna. By using a double can cantenna the range of the cantenna increased from 1 foot to around 7 to 10 feet. Earlier we used Net stumbler to detect the signal strength but it hanged over a certain values that is we could not refresh the network list when we went out of the coverage area. Hence we changed our software and used tomato signal detecting software. We also noticed that a small hole or gap in the reflector could lead to major signal loss. When we soldered the cans together to make a double cantenna then few gaps were left in between and radiated signal was lost. Hence we properly soldered the two cans so that signal is not lost while transmission. To further increase the effectiveness of our cantenna we can cover its outer surface with black paint or special chemicals. Black colour is helpful as it blocks the signal From being radiated from the surface of the can or the reflector.

216

Figure 9.17 Double can cantenna

217

Figure 9.18 Position of maximum radiation

9.6 SAFETY MEASURES 2.

Maintain proper distance from the soldering rod while soldering.

3.

Be careful with the edges of the can.

4.

Drill the can safely.

9.7 ADVANTAGES OF CANTENNA 1.

Cheap.

2.

Basic building elements easily available.

3.

Easy to construct. 218

4.

Rugged.

5.

Highly directional

6.

Easy to install

9.8 DISADVANTAGES OF CANTENNA Results can vary because of fluctuation of terrain or weather. Hence cantenna cannot be standardized.

219

IEEE 802.11s IMPLEMENTATION OF WIRELESS MULTIMEDIA CAMPUS NETWORK

220

CHAPTER 1

WIRELESS MESH NETWORK

1.1 WIRELESS MESH NETWORK: As various wireless networks evolve into the next generation to provide better services, a key technology, wireless mesh networks (WMNs), has emerged recently. In WMNs, nodes are com- prised of mesh routers and mesh clients. Each node operates not only as a host but also as a router, forwarding packets on behalf of other nodes that may not be within direct wireless transmission range of their destinations. A WMN is dynamically self-organized and self-configured, with the nodes in the network automatically establishing and maintaining mesh connectivity among them-selves (creating, in eect, an ad hoc network). This feature brings many advantages to WMNs such as low up-front cost, easy network maintenance robustness, and

Figure 1.1 Wired Infrastructure

221

reliable service coverage. Conventional nodes (e.g., desktops, laptops, DAs, PocketPCs, phones, etc.) equipped with ireless network interface cards (NICs) can connect directly to wireless mesh routers. Customers without wireless NICs can access WMNs by connecting to wireless mesh routers through, for example, Ethernet. Thus, WMNs will greatly help to users to be always-on-line anywhere anytime. Deploying a WMN is not too difficult, because all the required components are already available in the form of ad hoc network routing protocols, IEEE 802.11 MAC protocol, wired equivalent privacy (WEP) security, etc. Several companies have already realized the potential of this technology and other wireless mesh networking products. However, to make a WMN be all it can be, considerable research efforts are still needed. Researchers have started to revisit the protocol design of existing wireless networks, especially of IEEE 802.11 networks, ad hoc networks, and wire-less sensor networks, from the perspective of WMNs. Industrial standards groups are also actively working on new specifications for mesh net-working. For example, IEEE 802.11 [64,74], IEEE 802.15 [65,79], and IEEE 802.16 [66,111,135] all have established sub-working groups to focus on new standards for WMNs Figure 1.2: Wired Mesh Infrastructure

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1.2 NETWORK ARCHITECTURE WMNs consist of two types of nodes: mesh routers and mesh clients. Other than the routing capability for gateway/repeater functions as in a conventional wireless router, a wireless mesh router contains additional routing functions to support mesh networking. To further improve the flexibility of mesh networking, a mesh router is usually equipped with multiple wireless interfaces built on either the same or different wireless access technologies

In spite of all these differences, mesh and conventional wireless routers are usually built based on a similar hardware platform. Mesh routers can be built based on dedicated computer systems (e.g., embedded systems) and look compact, as shown in Fig. 1. They can also be built based on general-purpose computer systems (e.g., laptop/desktop PC).

Figure 1.3: Examples of mesh routers based on different embedded systems: (a)Power PC (b)Advanced Risc Machines(ARMs)

223

The architecture of WMNs can be classiffed into three main groups based on the functionality of the nodes:

1.2.1 Infrastructure/Backbone WMNs. The architecture is shown in Fig. 3, where dash and solid lines indicate wireless and wired links, respectively. This type of WMNs includes mesh routers forming an infrastructure for clients that connect to them. The WMN infrastructure/backbone can be built using various types of radio technologies, in addition to the mostly used IEEE 802.11 technologies. The mesh routers form a mesh of self-configuring, self-healing links among themselves. Typically, two types of radios are used in the routers, i.e., for backbone communication and for user communication, respectively. The mesh backbone communication can be established using long-range communication techniques including directional antennas. This approach also referred to as infrastructure meshing provides backbone for conventional clients and enables integration of WMNs with existing wireless networks through gateway/bridge functionalities of mesh router. Infrastructure/Backbone WMNs are the most commonly used type. For example, community and neighborhood networks can be built using infrastructure meshing. The mesh routers are placed on the roof of houses in a neighborhood, which serve as access points for users inside the homes and along the roads. Typically, two types of radios are used in the routers, i.e., for backbone communication and for user communication, respectively. The mesh backbone communication can be established using long-range communication techniques including directional antennas.

224

Figure 1.4: Infrastructure/backbone WMNs

1.2.2 Client WMNs.

Client meshing provides peer-to-peer networks among client devices. In this type of architecture, client nodes constitute the actual network to perform routing and configuration functionalities as well as providing end-user applications to customers. Hence, a mesh router is not required for these types of networks. The basic architecture is shown in Fig.3. In Client WMNs, a packet destined to a node in the network hops through multiple nodes to reach the destination. Client WMNs are usually formed using one type of radios on devices. Moreover, the requirements on end-user devices is increased when compared to infrastructure meshing, since, in Client WMNs, the endusers must perform additional functions such as routing and self-configuration.

225

Figure 1.5: Client WMN

1.2.3 Hybrid WMNs. This architecture is the combination of infrastructure and client meshing as shown in Fig. 5. Mesh clients can access the net work through mesh routers as well as directly meshing with other mesh clients. While the infrastructure provides connectivity to other networks such as the Internet, Wi-Fi, WiMAX, cellular, and sensor networks; the routing capabilities of clients provide improved connectivity and coverage inside the WMN. The hybrid architecture will be the most applicable case in our opinion.

226

Figure 1.6: Hybrid WMN

1.3 CHARACTERISTICS OF WMN The characteristics of WMNs are explained as follows: 1. Multi-hop wireless network. An objective to develop WMNs is to extend the coverage range of current wireless networks without sacrificing the channel capacity. Another objective is to provide non-line-of-sight (NLOS) connectivity among the users without direct line-of-sight

(LOS) links. To meet these

requirements, the mesh-style multi-hopping is indispensable ,which achieves higher throughput without sacrificing effective radio range via shorter link distances, less interference between the nodes, and more efficient frequency reuse. 227

2. Support for ad hoc networking, and capability of self-forming, self-healing, and self-organization. WMNs enhance network performance, because of _exible network architecture, easy deployment and conguration, fault tolerance, and mesh connectivity, i.e., multipoint-to-multi-point communications. Due to these features, WMNs have low upfront investment requirement, and the network can grow gradually as needed.

3. Mobility dependence on the type of mesh nodes. Mesh routers usually have minimal mobility, while mesh clients can be stationary or mobile nodes

4. Multiple types of network access. In WMNs, both backhaul access to the Internet and peer-to-peer (P2P) communications are supported. In addition, the integration of WMNs with other wireless networks and providing services to endusers of these networks can be accomplished through WMNs.

5. Dependence of power-consumption constraints on the type of mesh nodes. Mesh routers usually do not have strict constraints on power consumption. However, mesh clients may require power efficient protocols. As an example, a mesh-capable sensor requires its communication protocols to be power efficient. Thus, the MAC or routing protocols optimized for mesh routers may not be appropriate for mesh clients such as sensors, because power efficiency is the primary concern for wireless sensor networks

6. Compatibility and interoperability with existing wireless networks. For example, WMNs built based on IEEE 802.11 technologies must be compatible with IEEE 802.11 standards in the sense of supporting both mesh capable and conventional Wi-Fi clients. Such WMNs also need to be inter-operable with other wireless networks such as WiMAX, Zig- Bee, and cellular networks

7. Wireless infrastructure/backbone. As discussed before, WMNs consist of a wireless backbone with mesh routers. The wireless backbone provides large 228

coverage, connectivity, and robust ness in the wireless domain. However, the connectivity in ad hoc networks depends on the individual contributions of endusers which may not be reliable.

8. Integration. WMNs support conventional clients that use the same radio technologies as a mesh router. This is accomplished through a host-routing function available in mesh routers. WMNs also enable integration of various existing networks such as Wi-Fi, the Inter net, cellular and sensor networks through gateway/bridge functionalities in the mesh routers. Consequently, users in one network are provided with services in other networks, through the use of the wireless infrastructure. The inte-grated wireless networks through WMNs resembles the Internet backbone, since the physical location of network nodes becomes less important than the capacity and network topology

9. Dedicated routing and configuration. In ad hoc networks, end-user devices also perform routing and configuration functionalities for all other nodes. However, WMNs contain mesh routers for these functionalities. Hence, the load on end-user devices is significantly decreased, which provides lower energy consumption and high-end application capabilities to possibly mobile and energy constrained endusers. Moreover, the end-user requirements are limited which decreases the cost of devices that can be used in WMNs

10. Multiple radios. As discussed before, mesh routers can be equipped with multiple radios to perform routing and access functionalities. This enables separation of two main types of tra_c in the wireless domain. While routing and configuration are performed between mesh routers, the access to the network by end users can be carried out on a different radio. This significantly improves the capacity of the network. On the other hand, in ad hoc networks, these functionalities are performed in the same channel, and as a result, the performance decreases

229

11. Mobility. Since ad hoc networks provide routing using the end-user devices, the network topology and connectivity depend on the movement of users. This imposes additional challenges on routing protocols as well as on network configuration and deployment

1.4 APPLICATION SCENARIO

Research and development of WMNs is motivated by several applications which clearly demonstrate the promising market while at the same time these applications cannot be supported directly by other wireless networks such as cellular networks, ad hoc networks, wireless sensor networks, standard IEEE 802.11, etc. In this section, we discuss these applications. . 1.4.1 Broadband home networking. Currently broadband home networking is realized through IEEE 802.11 WLANs. An obvious problem is the location of the access points. Without a site survey, a home (even a small one) usually has many dead zones without service coverage. Solutions based on site survey are expensive and not practical for home networking, while installation of multiple access points is also expensive and not convenient because of Ethernet wiring from access points to backhaul network access modem or hub. Moreover, communications between end nodes less than two different access points have to go all the way back to the access hub. This is obviously not an efficient solution, especially for broadband networking. Mesh networking, as shown in Fig. below, can resolve all these issues in home networking. The access points must be replaced by wireless mesh routers with mesh connectivity established among them. Therefore, the communication between these nodes becomes much more flexible and more robust to network faults and link failures. Dead zones can be eliminated by adding mesh routers, changing locations of 230

mesh routers, or automatically adjusting power levels of mesh routers. Communication within home networks can be realized through mesh networking without going back to the access hub all the time. Thus, network congestion due to backhaul access can be avoided. In this application, wireless mesh routers have no constraints on power consumptions and mobility.

Figure 1.7 : WMNs for broadband home networking

1.4.2 Community and neighborhood networking.

In a community, the common architecture for network access is based on cable or DSL connected to the Internet, and the last-hop is wireless by connecting a wireless router to a cable or DSL modem. This type of network access has several drawbacks: 231

1. Even if the information must be shared within a community or neighborhood, all traffic must flow through Internet. This significantly reduces network resource Utilization.

2. Large percentage of areas in between houses is not covered by wireless services.

3. An expensive but high bandwidth gateway between multiple homes or neighborhoods may not be

shared and wireless services must be set up individually. As a result,

network service costs may increase.

4. Only a single path may be available for one home to access the Internet or communicate with neighbors

WMNs mitigate the above disadvantages through flexible mesh connectivity between homes, as shown in Fig.

232

Figure 1.8: WMNs for community networking

1.4.3 Enterprise networking.

This can be a small network within an office or a medium-size network for all offices in an entire building, or a large scale network among offices in multiple buildings. Currently, standard IEEE 802.11 wireless networks are widely used in various offices. Connections among them have to be achieved through wired Ethernet connections, which is the key reason for the high cost of enterprise networks. In addition, adding more backhaul access modems only increases capacity locally, but does not improve robustness to link failures, network congestion and other problems of the entire enterprise network. If the access points are replaced by mesh routers, as shown in Fig. 8, Ethernet wires can be eliminated. Multiple backhaul access modems can be shared by all nodes in the entire network, and thus, improve the robustness and resource utilization of enterprise networks. WMNs can grow easily as the size of enterprise expands. WMNs for enterprise 233

networking are much more complicated than at home because more nodes and more complicated network topologies are involved. The service model of enterprise networking can be applied to many other public and commercial service networking scenarios such as airports, hotels, shopping malls, convention centers, sport centers, etc.

Figure 1.9: WMNs for enterprise networking

234

1.4.4 Metropolitan area networks.

WMNs in metropolitan area have several advantages. The physical layer transmission rate of a node in WMNs is much higher than that in any cellular networks. For example, an IEEE 802.11g node can transmit at a rate of 54% Mbps. Moreover, the communication between nodes in WMNs does not rely on a wired backbone. Compared to wired networks, e.g., cable or optical networks MAN is an economic alternative to broadband networking, especially in underdeveloped regions. Wireless mesh MAN covers a potentially much larger area than home, enterprise, building, or community networks, as shown Fig. 9. Thus, the requirement on the network scalability by wireless mesh MAN is much higher than that by other applications.

Figure 1.10: WMNs for metropolitan area network

235

1.4.5 Transportation systems.

Instead of limiting IEEE 802.11 or 802.16 access to stations and stops, mesh networking technology can extend access into buses, ferries, and trains. Thus, convenient passenger information services, remote monitoring of in-vehicle security video and driver communications can be supported. To enable such mesh networking for a transportation system, two key techniques are needed: the high-speed mobile backhaul from a vehicle (car, bus, or train) to the Internet and mobile mesh networks within the vehicle, as shown in Figure.

Figure 1.11 WMNs for transportation system

.

1.4.6 Building automation.

In a building, various electrical devices including power, light, elevator, air conditioner, etc., need to be controlled and monitored. Currently this task is accomplished through standard wired networks, which is very expensive due to the complexity in deployment 236

and maintenance of a wired network. Recently Wi-fi based networks have been adopted to reduce the cost of such networks. However, this effort has not achieved satisfactory performance yet, because deployment of Wi-fis for this application is still rather expensive due to wiring of Ethernet. If BACnet (building automation and control networks) access points are replaced by mesh routers, as shown in Fig. 11, the deployment cost will be significantly reduced. The deployment process is also much simpler due to the mesh connectivity among wireless routers.

Figure 1.12: WMNs for building automation

237

1.4.7 Security surveillance systems.

As security is turning out to be a very high concern, security surveillance systems become a necessity for enterprise buildings, shopping malls, grocery stores, etc. In order to deploy such systems at locations as needed, WMNs are a much more viable solution than wired networks to connect all devices. Since still images and videos are the major traffic flowing in the network, this application demands much higher network capacity than other applications. In addition to the above applications, WMNs can also be applied to Spontaneous (Emergency/ Disaster) Networking and P2P Communications. By simply placing wireless mesh routers in desired locations, a WMN can be quickly established. For a group of people holding devices with wireless networking capability, e.g., laptops and PDAs, P2P communication anytime anywhere is an efficient solution for information sharing. WMNs are able to meet this demand. These Applications illustrate that WMNs are a superset of ad hoc networks, and thus can accomplish all functions provided by ad hoc networking.

1.5 COMPARISION WITH EXISTING TECHNOLOGIES

Table 1.1:Mesh vs. Ad-Hoc Networks

Ad-Hoc Networks

WMN

Multihop

Multihop

Nodes are wireless,

Nodes are wireless,

possibly mobile

some mobile, some fixed

238

May rely on infrastructure

It relies on infrastructure

Most traffic is user-to-user

Most traffic is user-to-gateway

TABLE 1.2: Mesh vs. Sensor Networks

Wireless Sensor Networks

WMN

Bandwidth is limited (tens of kbps)

Bandwidth is generous (>1Mbps)

In most applications, fixed nodes

Some nodes mobile, some fixed

Energy efficiency is an issue

Normally not energy limited

Resource constrained

Resources are not an issue

Most traffic is user-to-gateway

Most traffic is user-to-gateway

TABLE 1.3 WLAN Coverage

Wiring Costs

802.11

WMN

High

Low

239

Bandwidth

Very

Good

Good

Number of APs

As needed

Twice as many

Cost of APs

Low

High

1.6 MESH IMPLEMENTATION MODEL

Different factors affecting a wireless transmission rate for a mesh network.

1.6.1 Marginal S/N

Simplified model for packet loss: – P(delivery) = f(signal/noise) – Signal strength reflects attenuation – Noise reflects interference Perhaps marginal S/N explains intermediate delivery probabilities

1.6.2 Long Bursts of interference due to devices working in same spectrum Example: microwave Interference is any unwanted radio frequency signal that prevents you from watching television, listening to your radio or stereo, or talking on your cordless telephone. Interference may prevent reception altogether, may cause only a temporary loss of a signal, or may affect the quality of the sound or picture produced by your equipment.

240

Figure 1.13 Long Bursts of interference

1.6.3 Short bursts of interference due to concurrent sends from other routers Before you can resolve an interference problem you must isolate the actual interference source. Interference originates from many sources - the equipment itself, your residence, or the neighborhood. The two most common causes of interference are transmitters and electrical equipment. Communication systems that transmit signals (transmitters) are capable of generating interference; these include amateur radios, CBs, and radio and television stations. Electrical interference may be caused by power lines or electrical equipment

241

Figure 1.14: Short bursts of interference

1.6.3 Multipath interference

Multipath interference is a phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and, under the right condition, the two (or more) components of the wave interfere. The condition necessary is that the components of the wave remain coherent throughout the whole extent of their travel. The interference will arise owing to the two (or more) components of the wave having, in general, travelled a different length, and thus arriving at the detector out of phase with each other.

242

Figure 1.15 Multipath Interference

243

CHAPTER 2

HARDWARE REQUIREMENTS

2.1 HORN ANTENNA

In telecommunications, the term horn has the following meanings: In radio transmission, an open-ended waveguide, of increasing cross-sectional area, which radiates directly in a desired direction or feeds a reflector that forms a desired beam. Note 1: Horns may have one or more expansion curves, i.e., longitudinal cross sections, such as elliptical, conical, , or parabolic curves, and not necessarily the same expansion curve in each (E-plane and H-plane) cross section. Note 2: A very wide range of beam patterns may be formed by controlling horn dimensions and shapes, placement of the reflector, and reflector. Figure 2.1: Horn Antenna

244

2.2 PARABOLIC REFLECTOR A parabolic reflector (or dish or mirror) is a Parabola-shaped reflective device, used to collect or distribute energy such as light, sound, or radio waves. The parabolic reflector functions due to the geometric properties of the paraboloid shape: if the angle of incidence to the inner surface of the collector equals the angle of reflection, then any incoming ray that is parallel to the axis of the dish will be reflected to a central point, or "focus". Because many types of energy can be reflected in this way, parabolic reflectors can be used to collect and concentrate energy entering the reflector at a particular angle. Similarly, energy radiating from the "focus" to the dish can be transmitted outward in a beam that is parallel to the axis of the dish. Parabolic reflectors suffer from an aberration called coma. This is primarily of interest in telescopes because most other applications do not require sharp resolution off the axis of the parabola. The most common modern applications of the parabolic reflector are in satellite dishes, telescopes (including radio telescopes), parabolic microphones, and many lighting devices such as spotlights, car headlights, PAR Cans and LED housings.

2.3 CAT5 CABLE

Figure 2.2 :RJ45 CABLE

245

Category 5 cable, commonly known as Cat 5 or "Cable and Telephone", is a twisted pair cable type designed for high signal integrity. Many such cables are unshielded but some are shielded. Category 5 has been superseded by the Category 5e specification. This type of cable is often used in structured cabling for computer networks such as Ethernet, and is also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances).

Figure 2.3: RJ45 PLUG

246

2.3

IPOD TOUCH

Figure 2.4 IPOD Touch

The iPod touch is a portable media player and Wi-Fi mobile platform designed and marketed by Apple Inc. The product was launched on September 5, 2007 . The iPod touch adds the graphical user interfaces Cover Flow and Multi-Touch to the iPod line and 247

is available with 8, 16 or 32 GB of flash memory. It includes Apple's Safari web browser and is the first iPod enabling wireless access to the iTunes Store.[2] Beginning in June 2008, the iPod touch will also have access to the App Store.[3] The iPod touch has the iPhone's multi-touch interface, with a physical home button off the touch screen. The home screen has a list of buttons for the available applications. All iPod touch models have included the applications Music, Videos, and Photos (collectively duplicating the standard functions of the iPod classic), iTunes (providing access to the iTunes Music Store), Safari, YouTube, Calendar, Contacts, Clock, Calculator, and Settings. Later models added Mail (accessing POP/IMAP/SMTP e-mail), Maps, Stocks, Notes, and Weather,[4] which could also be added to the earlier models with the purchase of a software upgrade. Direct links to web sites can be added to the home screen by the user. First ask your self do you have secured or unsecured wireless connection?

If secured:

1. Go to Settings 2. Go to Wi-FI 3. Click on Your Wireless 4. Punch in your WEP key 5. Connect to it. If NOT Secured Follow all steps above except no.4

248

Figure 2.5 :IPOD interface

2.4 WIRELESS ROUTERS 2.4.1 What Is a Router? A router is a computer whose software and hardware are usually tailored to the tasks of routing and forwarding, generally containing a specialized operating system (e.g. Cisco's IOS ), RAM, NVRAM, flash memory, and one or more processors. High-end routers contain many processors and specialized Application-specific integrated circuits (ASIC) and do a great deal of parallel processing. Chassis based systems like the Nortel MERS8600 or ERS-8600 routing switch, have multiple ASICs on every module and allow for a wide variety of LAN, MAN, METRO, and WAN port technologies or other connections that are customizable. 249

2.4.2 Wireless Router A wireless router is a network device that performs the functions of a router but also includes the functions of a wireless access point. It can function in a wired LAN, a wireless only LAN, or a mixed wired/wireless network. Most current wireless routers have the following characteristics: LAN ports, which function in the same manner as the ports of a network switch A WAN port, to connect to a wider area network. The routing functions are filtered using this port. If it is not used, many functions of the router will be bypassed. Wireless antennae. These allow connections from other wireless devices (NICs (network interface cards), wireless repeaters, wireless access points, and wireless bridges, for example).

2.4.3 WRT54G Linksys WRT54G (and variants WRT54GS, WRT54GL, and WRTSL54GS) is a WiFi capable residential gateway from Linksys. The device is capable of sharing Internet connections amongst several computers via 802.3 Ethernet and 802.11b/g wireless data links.

250

Figure 2.6: Linksys WRT54G router

Figure 2.7: Linksys WRT54G router and related accessories

251

The WRT54G is notable for being the first consumer-level network device that had its firmware source code released to satisfy the obligations of the GNU GPL. This allows programmers to modify the firmware to change or add functionality to the device. Several third-party firmware projects provide the public with enhanced firmware for the WRT54G.. This product has been known to be well suited for small businesses. The WRT54G is also quite notable for being a piece of networking equipment that even novice home computer users understand and use each day. The WRT54G can be thought of as bridging the gap between high-end commercial networking and the now-booming home networking.

2.4.4 WRT54GL Linksys released the WRT54GL in 2005 to support third-party firmware based on Linux, after the original WRT54G line was switched from Linux to VxWorks, starting with version 5. The WRT54GL is technically a reissue of the version 4 WRT54G.

2.4.4.1 LINKSYS WRT54GL version 1.1 The ―L‖ in the model number, WRT54GL, stands for Linux. The previous models of the WRT54G are also powered by Linux (version 1.0 to 4.0). The latest version of the Linksys WRT54G is version 5.0 and runs VxWorks. The move to VxWorks cut the memory footprint in half according to Mani Dhillon, senior manager of product marketing at Linksys. This claim appears to be based in fact because the Version 5.0 model only has 2MB of Flash and 8MB of SDRAM. ―We still wanted to have a Linux SKU

for

the

Linux

audience,‖

said

252

Dhillon,

hence

the

WRT54GL.

2.4.4.2 Linksys WRT54GL Features Linux Kernel 2.4 Based on the Broadcom BCM5352E SoC Hardware design is the WRT54G Version 4.0 After market firmware upgrades All-in-one Internet-sharing Router, 4-port Switch, and 54Mbps Wireless-G (802.11g) Access Point Shares a single Internet connection and other resources with Ethernet wired and Wireless-G and -B devices Push button setup feature makes wireless configuration secure and simple High security: TKIP and AES encryption, wireless MAC address filtering, powerful SPI firewall The Linksys Wireless-G Broadband Router is really three devices in one box. First, there's the Wireless Access Point, which lets you connect to both a Wireless-G (802.11g at 54Mbps) and Wireless-B (802.11b at 11Mbps) devices to the network. There's also a built-in 4-port full-duplex 10/100 Switch to connect your wired-Ethernet devices together. Connect four PCs directly, or attach more hubs and switches to create as big a network as you need. Finally, the Router function ties it all together and lets your whole network share a high-speed cable or DSL Internet connection.

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Figure 2.8: Internal architecture of Linksys WRT54GL Router

254

The WRT54G has gained in popularity due to the fact that one can upgrade the unit with after market firmware. This is possible because the WRT54G runs Linux and uses other Open Source software in the box. As required by the GPL, Linksys has made available the source code and can be downloaded from the Internet. Hackers picked up this code and created new development branches that added features such as SSHD.

Figure 2.9 :LINKSYS WRT54GL block diagram

255

2.5.5 Linksys WRT54G Router: First, when we began our project on setting up the wireless mesh network, we started with a Linksys WRT54G Router. Linksys WRT54G (and variants WRT54GS, WRT54GL, and WRTSL54GS) is a Wi-Fi capable residential gateway from Linksys. The device is capable of sharing Internet connections amongst several computers via 802.3 Ethernet and 802.11b/g wireless data links. The WRT54G is notable for being the first consumer-level network device that had its firmware source code released to satisfy the obligations of the GNU GPL. This allows programmers to modify the firmware to change or add functionality to the device. Several third-party firmware projects provide the public with enhanced firmware for the WRT54G.

Figure 2.10:Linksys WRT54G version 1.0

The original WRT54G was first released in December 2002. It comes with a 4+1 port network switch (the Internet/WAN port is also in the same internal network switch, but on a different VLAN). The devices have two removable antennas connected through Reverse Polarity TNC connectors. The WRT54GC router is an exception and has an internal antenna with optional external antenna. As a cost-cutting measure, the design of 256

the latest version of the WRT54G no longer has detachable antennas or TNC connectors. Instead, version 8 routers simply route thin wires into antenna 'shells' eliminating the connector. As a result, Linksys HGA7T and similar external antennas are no longer compatible with this model.

TABLE 2.1: WRT54G Router configuration

257

Table2.1(contd.)

258

Table 2.1(contd.)

Due to less RAM capacity we could not flash Linksys WRT54G Router with open source firmware. Hence, we shifted to Linksys WRT54GL Router with more RAM capacity. Linksys WRT54GL Router: Linksys released the WRT54GL in 2005 to support third-party firmware based on Linux, after the original WRT54G line was switched from Linux to VxWorks, starting with version 5. The WRT54GL is technically a reissue of the version 4 WRT54G.

259

TABLE 2.2: WRT54GL Router configuration

The WRT54G router has open WRT as its proprietary firmware, but open WRT supports wired mesh routing but not for wireless mesh routing. Hence we needed another firmware. Next, we upgraded to freifunk firmware which is being used in Meraki Network in Africa, we were able to accomplish mesh routing but were having some trouble with the software itself. It was bit complicated and being German based there was not much information on troubleshooting. Finally we upgraded our routers to ‗tomato‘ firmware. The wireless mesh network was successfully deployed and we tested the network for various applications and services. The various applications and services included:

1. Voice/video chat 2. Voice over internet protocol (VOIP) 3. File transfer 4. Desktop sharing 5. White board 260

CHAPTER 3

SOFTWARE REQUIREMENTS

3.1 MS WINDOWS

MS WINDOWS is one of the most widely used operating systems in India. It was of great help for our project.

3.2 LINUX—UBUNTU GUTSY RIBBON

Ubuntu in English, is an operating system for desktops, laptops, and servers. It has consistently been rated among the most popular of the many Linux distributions.[4][5][6][7] Ubuntu's goals include providing an up-to-date yet stable Linux distribution for the average user and having a strong focus on usability and ease of installation. It is a derivative of Debian, another popular distribution. Ubuntu is sponsored by Canonical Ltd, owned by South African entrepreneur Mark Shuttleworth. The name of the distribution comes from the African concept of ubuntu which may be rendered roughly as "humanity toward others", "we are people because of other people", or "I am who I am because of who we all are", though other meanings have been suggested This Linux distribution is named as such to bring the spirit of the philosophy to the software world. Ubuntu is free software and can be shared by any number of users.

3.2.0 Configuring Wi-fi in UBUNTU Simply click on the Network-Manager icon to see all available wireless networks, and click on the network to connect to it. If wireless authentication is needed, be it WEP, 261

WPA, or 802.1x, a network-manager dialog will pop up asking for your authentication details. If network manager does not solve the problem, the first step should be to see which driver your wireless card needs. Do a search for your card on Google and in the Ubuntu Forums to find out which driver you need. Many of the drivers are already included in Ubuntu, but some newer drivers may not be present. Next, you need to find out if the driver is loaded. As an example, if you have an Intel Centrino and it uses the ipw2200 driver, run this command: Sudo lsmod | grep ipw2200 Replace ipw2200 with the relevant driver for your card. If you get some lines returned, the driver is loaded and working. If nothing is returned, your card is either not supported or the driver is not included in Ubuntu. You should refer to the Ubuntu Forums for further support. With the card identified, you now need to get connected. The easiest way to do this is to select System -> Administration -> Networking. Inside this tool you should see an icon for your wireless card. Select it and click the Properties button. Add the name of the wireless network and a password if applicable. If you are using a normal password such as s3cr3tpass, select Plain (ASCII) from the Key type box. If you are entering the long numeric password, use the Hexedecimal option. If you don't have a password on your wireless network, leave the Key type and WEP key boxes empty. If you are automatically assigned an IP address, use the Configuration box to select DHCP. Otherwise, select Static IP Address, and enter the details of your network in the boxes.

262

3.2.1 TCPDump tcpdump is a common computer network debugging tool that runs under the command line. It allows the user to intercept and display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. It was originally written by Van Jacobson, Craig Leres and Steven McCanne who were, at the time, working in the Lawrence Berkeley Laboratory Network Research Group. Tcpdump is frequently used to debug applications that generate or receive network traffic. It can also be used for debugging the network setup itself, by determining whether all necessary routing is occurring properly, allowing the user to further isolate the source of a problem.It is also possible to use tcpdump for the specific purpose of intercepting and displaying the communications of another user or computer. A user with the necessary privileges on a system acting as a router or gateway through which unencrypted traffic such as TELNET or HTTP passes can use tcpdump to view login IDs, passwords, the URLs and content of websites being viewed, or any other unencrypted information.

3.2.2 NdisWrapper 263

NdisWrapper is a free software driver wrapper that enables the use of Microsoft Windows drivers for wireless network devices (cards, USB modems, and routers), on Unix-like operating systems. Ndiswrapper works by implementing the Windows kernel and NDIS APIs, and dynamically linking the driver to this implementation. Native drivers for Unix and Linux are not available for many wireless network adapters, as manufacturers supply neither drivers nor the information required to write them. Ndiswrapper allows Windows drivers available for virtually all adapters to be used under Unix and Linux

3.2.3 Wi-fi Radar

Wi-fi

Radar

is

a

Python/PyGTK2

utility

for

managing

WiFi

profiles.

It enables you to scan for available networks and create profiles for your preferred networks. At boot time, running WiFi Radar will automatically scan for an available preferred network and connect to it. You can drag and drop your preferred networks to arrange the profile priority.

Figure 3.1 WiFi Radar

264

3.2.4 Wireless Tools The Wireless Tools (WT) is a set of tools allowing to manipulate the Wireless Extensions. They use a textual interface and are rather crude, but aim to support the full Wireless Extension. There are many other tools you can use with Wireless Extensions, however Wireless Tools is the reference implementation. iwconfig manipulate the basic wireless parameters iwlist allow to initiate scanning and list frequencies, bit-rates, encryption keys... iwspy allow to get per node link quality iwpriv allow to manipulate the Wireless Extensions specific to a driver (private)

3.3 MATLAB AND SIMULINK MATLAB® is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numeric computation. Using the MATLAB product, you can solve technical computing problems faster than with traditional programming languages, such as C, C++, and Fortran. You can use MATLAB in a wide range of applications, including signal and image processing, communications, control design, test and measurement, financial modeling and analysis, and computational biology. Add-on toolboxes (collections of specialpurpose MATLAB functions, available separately) extend the MATLAB environment to solve particular classes of problems in these application areas. MATLAB provides a number of features for documenting and sharing your work. You can integrate your MATLAB code with other languages and applications, and distribute your MATLAB algorithms and applications. 265

Key Features: High-level language for technical computing Development environment for managing code, files, and data Interactive tools for iterative exploration, design, and problem solving Mathematical functions for linear algebra, statistics, Fourier analysis, filtering, optimization, and numerical integration 2-D and 3-D graphics functions for visualizing data Tools for building custom graphical user interfaces Functions for integrating MATLAB based algorithms with external applications and languages, such as C, C++, Fortran, Java, COM, and Microsoft Excel

3.4

OTHER SOFTWARES USED

3.4.1 MAD Wi-fi

MadWifi is one of the most advanced WLAN drivers available for Linux today. It is stable and has an established userbase. The driver itself is open source but depends on the proprietary Hardware Abstraction Layer (HAL) that is available in binary form only. The current stable release is v0.9.4. We tested the wireless mesh network for using Madwifi firmware, but we faced some glitches with the deployment of the driver. First the madwifi being Linux based worked only on Linux and we were having difficulties getting the drivers for various routers. Yet we were able to run Linksys WRT54USBG card under Ubuntu 7.04.

266

3.4.2 Netmeeting

NetMeeting provides people around the world with a whole new way of communicating. With NetMeeting we can participate in meetings, collaborate in files using NetMeeting features, and share information over the Internet or your corporate intranet. NetMeeting features allows to place calls using directory servers, conferencing servers, and Web pages. NetMeeting makes it easier to place calls over the Internet, the organization's intranet, and with telephones. Figure 3.2 Netmeeting

267

One can work easily with other meeting participants by sharing programs. Only one computer needs to have the program, and all participants can work on the document simultaneously. In addition, people can send and receive files to work on. NetMeeting's audio and video lets see and hear other people. Even if one is unable to transmit video, one can still receive video calls in the NetMeeting video window. With the Chat feature, you can talk with multiple people. In addition, Chat calls can be encrypted, ensuring that your meetings are private. Hence it provides following options to user: 1. Video/audio chat 2. Remote desktop sharing 3. File transfer 3.4.3 Netstumbler

Network Stumbler (also known as NetStumbler) is a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards. It runs on Microsoft Windows operating systems from Windows 98 on up to Windows Vista (under compatibility mode). A trimmed-down version called MiniStumbler is available for the handheld Windows CE operating system.

268

Figure 3.3 Graph obtained from net stumbler

269

Figure 3.4:A typical Netstumbler Window

The program is commonly used for: Wardriving Verifying network configurations Finding locations with poor coverage in a WLAN Detecting causes of wireless interference Detecting unauthorized ("rogue") access points Aiming directional antennas for long-haul WLAN links

270

3.4.4 SKYPE

Skype is a software program that allows users to make telephone calls over the Internet. Calls to other users of the service are free of charge, while calls to landlines and cell phones can be made for a fee. Additional features include instant messaging, file transfer and video conferencing.

Figure 3.5:A Skype Window

271

3.4.5 PRTG Traffic monitor PRTG Traffic Grapher is an easy to use Windows software for monitoring and classifying bandwidth usage. It provides system administrators with live readings and long-term usage trends for their network devices. The most common usage is

Figure 3.6: PRTG TRAFFIC MONITOR

bandwidth management, but you can also monitor many other aspects of your network like memory and CPU utilizations. Fig Top Protocols Network traffic 272

Figure 3.7: Table 24 hours- 5 min averages

273

Figure 3.8:

Live graph-60 Minutes- 10 sec Interval

274

Figure 3.9: Data

275

Figure 3.5:ANGRY IP

276

Figure 3.10: Angry IP Scanner

277

CHAPTER 4

FIRMWARE

4.1 TOMATO FIRMWARE Tomato Firmware is a free HyperWRT + tofu based, Linux core firmware for several wireless routers, most notably the Linksys WRT54G (including the WRT54GL and WRT54GS), Buffalo AirStation and Asus Routers. Tomato is based on the GPL sourcecode released by Linksys, this includes proprietary binary modules from the chipset manufacturer Broadcom. Portions of the code are licensed under the GNU General Public License, the source code for the user interface is under a more restrictive license which forbids use without the author's permission. Among notable features is the user interface, which makes heavy use of AJAX as well as an SVG-based graphical bandwidth monitor. Tomato is free open source Linux-based firmware for several Broadcom-based Wi-Fi routers, including the Linksys WRT54G. The major emphasis of Tomato is on stability, speed and efficiency.

Tomato is notable for its web-based user interface that includes several types of bandwidth usage charts, advanced QoS access restriction features , raised connection limits which enables P2P networking, and support for 125 High Speed Mode (marketed by Linksys as "SpeedBooster").

278

4.1.1 Supported devices

Linksys WRT54G (v1-v4 only), WRT54GS (v1-v4 only), WRT54GL (v1 & v1.1), WRTSL54GS (no USB support) Tomato is not compatible with Linksys WRT54G/GS v5-v7 or newer WRT54G/GS routers. These routers do not run Linux.

4.1.2 Licensing While the core source code is licensed under GPLv2, the source code for the user interface is under a more restrictive license which forbids use without the author's permission.

4.1.3 Upgrading The Firmware Open the GUI in your browser. The default URL is http://192.168.1.1/ Click Administration, then Upgrade. Select any of the files and click the Upgrade button. Wait for about 2 minutes while the firmware is uploaded & flashed.

4.1.4 Menus in Tomato The following is a listing of all of the available menu options in the Tomato GUI, and their functions. As settings on a page are edited the Save button at bottom of page must be clicked before navigating to another page otherwise the newly entered settings are not saved.

4.1.4.1 Status Provides information on the current condition of the router.

279

4.1.4.2 Overview The Overview screen shows information on the current state of the router. It is organized into four sections:

4.1.4.3 System Gives current overall system status, like the amount of time the router has been running, CPU load, and memory usage.

4.1.4.4 WAN Gives information on the Wide Area Network (Internet) connection.

4.1.4.5 LAN Gives a summary of the settings related to the Local Area Network, and the MAC Address for the wired portion of the network.

4.1.4.6 Wireless Gives information on the wireless portion of the Local Area Network.

4.1.4.7 Device List Provides a list of the current devices that have been assigned an IP address by the DHCP server. Devices are listed by Interface, which indicates where on the router they are connected:

br0 refers to Wired Ethernet (LAN) devices. In other words, devices that are connected to the router on the four Ethernet ports (either directly or via a hub or switch).

280

eth1 refers to Wireless Ethernet (WLAN) devices. In other words, devices that are connected to the router via the wireless radio.

vlan1 refers to your WAN (Internet) connection. In other words, the connection to your Internet modem (Cable modem, DSL modem, or upstream router).

4.1.4.8 Logs Allows you to view the Internal system logs (assuming Internal Logging is enabled - see "Logging" under "Administration").

4.1.4.9 Bandwidth Displays

the

Bandwidth

of

the

Interfaces.

They

can

be

excluded

at

Administration/Bandwidth Monitoring

4.1.4.10 Real-Time Displays a chart, updated every two seconds, of the last 10 minutes of bandwidth used. Tabs at the top allow you to select the various interfaces for detail on the bandwidth for that interface. The charts are made up in Scalable Vector Graphics (SVG) .

4.1.4.11 Last 24 Hours Displays a chart, updated every two minutes, of the last 4/6/12/18/24 hours of bandwidth usage and the total data during the period. Tabs at the top allow you to select the various interfaces for detail on the bandwidth for that interface.

281

4.1.4.12 Daily Displays the summary of daily bandwidth consumption. It also shows the difference in bandwidth usage compared to the day before.

4.1.4.13 Monthly Displays the summary of monthly bandwidth consumption. It also shows the difference in bandwidth usage compared to the month before. The start date of the month can be changed at "Administration->Bandwidth Monitoring->First Day Of The Month" to match the start date of data counter of any particular Internet plan.

4.1.5 Tools

4.1.5.1 Ping Allows you to ping computers on the Internet to verify connectivity. Simply enter the URL or IP address (Internet only) to ping, customize the number of retries or packet size if you wish, and press [PING]. Results will be displayed when the ping is complete.

4.1.5.2 Trace Allows you to perform a TRACERT (Trace Route) from your router to any Internet server. Enter the URL or IP address to trace to, and optionally the maximum hops and/or wait times, and press [TRACE]. Results are displayed when the trace is complete.

4.1.5.3 Wireless Survey Scans the local area for other Wireless Access Points, and gives received signal strength information and other data.

282

4.1.5.4

WOL

Allows you to send Wake-on-LAN (WOL) packets to computers on your network.

4.1.5.5 Basic Controls the most basic settings for the router.

4.1.6 Network Allows you to set up the Internet / Wide Area Network (WAN) connection that the router uses, and the basic parameters of the Local Area Network (LAN).

4.1.6.1 WAN / Internet Specifies how your router should connect to the Internet. Normally, this is done via an Ethernet cable connected from the WAN/Internet port to a Cable or DSL Modem.

Type: Specifies the type of connection used. The rest of the parameters are variable, and based on the type of connection. The default for most Cable modems is "DHCP", meaning that the router simply talks to your cable modem and is automatically assigned an IP address and other connection data. DSL connections generally use PPPoE, which usually requires a username and password (provided by your DSL provider)

4.1.6.2 LAN Controls setup of the Local area Network (LAN), which includes settings for wired and wireless clients connected to the router.

4.1.6.3 Router IP Address The IP address assigned to the router on the LAN. Default is 192.168.1.1.

283

4.1.6.4 Subnet Mask The default of 255.255.255.0 means that anything starting in the first three numbers as the router (default 192.168.1.x) is assumed to be on the Local Network. Making this too broad means that some Internet servers may be inaccessible.

4.1.6.5 Static DNS Allows you to list a series of DNS servers manually (as opposed to getting them from your Internet Service Provider). Useful if your ISP's DNS servers are slow or unreliable, or if you prefer a different one.

4.1.6.6 DHCP Server Dynamic Host Configuration Protocol (DHCP) is a protocol used by networked computers (clients) to obtain IP addresses. Use this to control the IP addresses that your router hands out to computers connected to the Wired or Wireless Local Network. If checked, the router will hand out addresses within the range specified. You may also customize the amount of time before computers on the LAN will renew their IP addresses (the Lease Time) and specify a Windows Internet Name Service (WINS) server if you use WINS.

4.1.7 Wireless Controls the connection over the Wireless Local Area Network.

4.1.7.1 Enable Wireless If checked, Wireless access will be allowed. 4.1.7.2 MAC Address Displays the MAC address assigned to the Wireless radio on the router.

284

Wireless Mode: The normal setting for this is Access Point, which allows clients to connect to this router. The router can also be used in Wireless Distribution System (WDS) mode, and it can also connect to a Wireless ISP in Wireless Client. Another possible mode is Wireless Ethernet Bridge mode. This allows it to connect to another gateway router while still keeping all computers connected to both routers in the same subnet. Note: If the router is used as a wireless client or Wireless Ethernet Bridge, it cannot be used as an access point at the same time.

4.1.7.3 B/G Mode This may be Mixed (B+G), B-Only (restricted to 802.11b), or G-Only (restricted to 802.11g). If you set this to B-Only or G-Only, connection attempts from the other protocol may be seen as interference. Recommend leaving this set to "Mixed".

4.1.7.4 SSID Wireless router identifier. Allows you to uniquely identify your router and differentiate it from other routers in range.

4.1.7.5 Broadcast If checked, the SSID will be broadcast, allowing the router to be found more easily. Disabling this is a very limited security measure. Casual scans will not be able to find the router, but anyone running sniffing software can easily find it.

4.1.7.6 Channel The 2.4Ghz range channel used by the router. Generally, it is best to use the Wireless Survey under Tools to find any other access points in range, and use the frequency that is the furthest from any other frequency in use.

285

4.1.7.7 Security Allows you to secure your wireless connections. WPA and/or WPA2 personal are the most secure protocols. Disabled means all connections are unencrypted and anyone can access the router. WEP is an older encryption protocol. While better than nothing, it is easily broken.

4.1.8

Identification

4.1.8.1 Router Name Allows you to change the name of the router, which appears on login and administration screens.

4.1.8.2 Hostname Use if your ISP or connection requires it.

4.1.8.3

Domain Name

Use if your ISP or connection requires it.

4.1.9

Time

4.1.9.1 Router Time Displays current router time.

4.1.9.2 Time Zone

286

Tell the router which time zone you are in so it can adjust to local time. If you set this to Custom, you can enter a string that allows you to customize a time zone. 4.1.9.3 Auto Daylight Saving Time If checked, the router will compensate for Daylight Saving Time. If not, it will always use Standard Time.

4.1.9.4 Auto Update Time How often the router connects to a Network Time Protocol (NTP) server to update its internal clock.

4.1.9.5 Trigger Dial On Demand If checked, the router will force a connection as needed to update time. If not checked, the router will only check time if a connection to the Internet is already established.

4.1.9.6 NTP Time Servers List of NTP servers to use to update the time.

4.1.10

DDNS

Dynamic DNS, a special DNS registry/server that can be updated on frequent IP address shuffles. Instead of having to know your IP address each time it changes, a computer on your network can run a special network program that submits your updated IP address, which you can then refer to via a standard URL issued by your DDNS provider. Most DDNS providers offer a free personal account for you to use. As an alternative to running an application on one of your PCs, Tomato provides a builtin DDNS client right in the firmware that supports a number of DDNS providers.

287

For most DDNS providers, you simply select the provider from the pull-down list, and enter your username, password, and hostname. Detailed instructions on operating each DDNS provider's account can be found at their web site.

4.1.11 Static DHCP This is a simple way to ensure that each of the clients that connects to your Tomato router gets the same IP address each time. Simply enter the MAC address for your device (which you can find on the "Device List"), and enter your preferred IP address. Generally, it's best to use an IP address that is within the subnet range for your Tomato router, but outside the normal DHCP assignment range. In other words, use an address that starts with the same three numbers (default 192.168.1.x) as your router, but has a fourth number that is not likely to be assigned to any clients by the normal DHCP settings. If you have the DHCP server set to assign IP addresses in the range of 192.168.1.100 to 192.168.1.150, for example, good choices for Static DHCP assignments would be either in the 192.168.1.2 - 192.168.1.99 range, or 192.168.1.151 - 192.168.1.254. An easy way to add an IP address to the Static DHCP list, is to go to the "Device List" and click on the IP address of the device you want to make Static. This will take you to the Static DHCP function and all you need to do is edit the device name (optional) and click "Add". (don't forget to click "Save" to commit)

4.1.12 Wireless Filter The Wireless Filter allows you to configure which wireless equipped computers may or may not communicate with the router depending on their MAC addresses. While a decent basic security measure, understand that all MAC addresses are transmitted in cleartext, and may be intercepted. This should not be used as a primary means of security.

288

4.1.13 Miscellaneous

4.1.13.1 Boot wait time Specifies the length of time the router will pause during startup, before attempting to load the firmware. This pause represents a period where a new firmware can be flashed to the router via TFTP, if the firmware on the flash chip has been corrupted.

4.1.13.2 WAN Port Speed: Specifies the speed and duplex setting for the WAN interface port.

4.1.14 Routing

4.1.14.1 Current Routing Table Shows your current routing table.

4.1.14.2 Static Routing Table Allows you to add static routing entries if you have more than 1 router on your network.

4.1.14.3 Wireless Controls advanced settings for the connection over the Wireless Local Area Network.

4.1.14.4 Afterburner Broadcom Afterburner is a 802.11g Standards Enhancement to provide additional speed for home wireless networks while remaining compatible with all Wi-Fi CERTIFIED™ 802.11b/g Products. When enabled, it allows 125 Mbps mode.

4.1.14.5 AP Isolation: A prime example would be like in a hotspot (e.g. coffeeshop like Starbucks, hotels) wherein a lot of computers connect randomly to the network. Since all computers are 289

connected to 1 single network there is a possibility that they could access each other which may result in unwanted hacking. AP isolation will help prevent this by making each and every single computer a separate entity on their own. When enabled, prevents wireless devices from communicating with each other. If disabled, the unit will switch traffic from one wireless client to another.

4.1.14.6 Authentication Type Controls whether clients must use shared keys to authenticate. This setting is disabled (i.e. forced) in some security modes.

4.1.14.7 Basic Rate Sets mandatory rate list transmitted by the AP which must be supported in order to connect. Some old 802.11b clients can only connect if this is set to 1-2Mbps.

4.1.14.8 Beacon Interval Sets the amount of time between beacon transmissions in milliseconds. A longer interval can save power on sleeping clients.

4.1.14.9 CTS Protection Mode When set to Auto, enables a mode which ensures 802.11b devices can connect when many 802.11g devices are present.

4.1.14.10 Distance / ACK Timing Sets the approximate maximum distance in meters from which clients can connect. May be useful in preventing distant "cantenna leeches" from connecting. It will not prevent snooping, however. Setting to 0 disables this function.

4.1.14.11 Frame Burst Enables frame burst mode which increases throughput but does not work well with more than about three clients. 290

4.1.14.12 Maximum Clients Sets the maximum number of wireless clients that can connect at once.

4.1.14.13 Multicast Rate Sets the signalling rate used for multicasting.

4.1.14.14 Preamble Selects long or short preamble for 802.11b. Short will increase throughput, but some older 802.11b devices require the long preamble.

4.1.14.15 RTS Threshold Sets the minimum packet size in bytes which triggers Request to Send/Clear to Send signalling. A number higher than the Fragmentation Threshold serves to disable the function. It is normally not needed but may be useful in adverse conditions.

4.1.14.16 Receive Antenna Selects which antenna is used for receiving. These settings are primarily useful for external antennas. Single antenna units should be set to Auto.

4.1.14.17 Transmit Antenna Selects which antenna is used for transmitting.

4.1.14.18 Transmit Power 291

Sets the transmit power in milliwatts. High settings may overheat and shorten the life of the transmitter.

4.1.14.19 Transmission Rate Allows forcing a lower maximum signalling rate, which can be useful in adverse conditions.

4.1.14.20 WMM Enables Wireless Multimedia extensions which provide automatic QoS and power saving. Primarily intended for wi-fi phones and the like.

4.1.14.21 No ACK Controls whether WMM packets require acknowledgment. Enabled sets No Acknowledgment which allows higher throughput and lower latency when some packet loss is acceptable (i.e. for VoIP).

4.1.15 Port Forwarding Once you have set up your router you will have your own Local Area Network (LAN) managed by the router. You inevitably will have many devices connected to your LAN all using the same internet connection. This causes a problem because different devices on your LAN will need specific data that is coming in from (or going out to) the internet. Port Forwarding allows your router to control the flow of data to and from the internet, and make sure the router knows which device (ie computer, webcam, VoIP telephone etc) connected to your LAN sent/requested/needs each packet of data. Usually packets coming in from the Internet will be in response to some request that one of your devices connected to your LAN has made (ie a VoIP phone making a request to connect a telephone call) . In these cases, the router keeps track of which device made the request, and forwards the response back to that same device. 292

4.1.16 Basic Allows you to specify simple port forwarding where all packets received on the specified External Ports will be routed to the specified Internal Address. eg you can forward all incoming data on ports 5060 and 5061 (used for SIP protocol to initiate a VoIP telephone call) to your VoIP telephone. Optionally, you can change the local port by specifying Int Port. This is also known as Port Redirection. This technique is handy, for example, if you have two web servers. Both could be listening on the default port (80), but the router could be set to forward received packets on Internet Port 80 to Port 80 on the first web server, and packets on Internet Port 81 to Port 80 on the second web server. The "External Ports" box can contain a single port (ie 8080) or a range of ports (5060:5061). The "Int Port" can be left blank. The "Internal Address" is the IP address of the device on your LAN (ie 192.168.1.2)

4.1.17 Triggered Port Triggering is an on-demand port forward. The router will look for an outbound connection on a specified port, and will forward all of the requested ports to whatever computer initiated the outbound connection. Under the Trigger Ports, you would enter a list of the ports that your computer will use to initiate the forwarding. Then you specify the ports you want to forward to that computer under Forwarded Ports. Any computer that sends outbound packets on any of the ports listed in Trigger Ports will then have all unsolicited packets received from the Internet on the Forwarded Ports sent to it.

4.1.18 UPnP Universal Plug and Play (UPnP) allows devices on your network to set their own port forwards. A computer running a web server, for example, can tell the router to forward all

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communications on port 80 and/or 443 to it. This allows your local devices to add, delete, and update port forwards at will. There are some security disadvantages to UPnP, such as a trojan horse or other "bad" software package being able to forward ports to a given machine so the malware can use your computer as an Internet server. However, there are also security advantages to UPnP, since any well-behaved UPnP application will request cancellation of its forwarded ports when it shuts down or no longer needs them. This reduces the number of unneeded forwarded ports.

4.1.19 QoS QoS, or Quality of Service, allows you to prioritize data, slowing down less important data to allow more important data to get through first. This is primarily useful for outbound data (data going from your computers to the Internet). Inbound data cannot be prioritized effectively because it has already passed through the bottleneck (your Internet connection) by the time the router has a chance to evaluate it. QoS in Tomato has ten levels of priority. HIGHEST will always get the very highest priority (use sparingly) and CLASS-E (labeled as E) is the lowest-priority class. If the upstream bandwidth becomes over-saturated (more packets want to go out than the connection can send), lower-priority packets will be delayed (and possibly eventually discarded) to make room for higher-priority packets.

4.1.20 Basic Settings

4.1.20.1 Enable QoS If checked, QoS will be enabled. If not checked, QoS will be disabled.

4.1.20.2 Prioritize ACK

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Prioritizes the sending of ACK (Acknowledgment) packets. Recommended: Checked (on).

4.1.20.3 Max Bandwidth One of the major limitations of QoS in most Linksys routers is their inability to determine the upstream speed of the Internet connection. This is true of many router models. The most effective way to tune QoS is to do an Internet speed test with QoS turned off. Then enter about 90% of the tested upstream (upload) bandwidth into the Max Bandwidth field. This will allow the router to properly determine how much bandwidth is available and prioritize packets accordingly.

4.1.20.4 Class E (the percentages under Outbound Rate/Limit) This specifies the minimum and maximum percentages of the connection each classification is allowed to consume. This is allocating, rather than prioritizing, and is useful for cases where you want to specify that certain classes of connection should never receive more than a given percentage of your upload bandwidth. Set each class to 1%100% to allow each class unlimited access to the bandwidth (with higher priority classes receiving only higher priority, and not "reserved" amounts).

4.1.20.5 Inbound Limit: This allows you to limit the overall amount of data coming in to your router, and allocate maximum percentages of that bandwidth for each QoS service. Under certain circumstances, this setting is useful, but is a very inefficient way to control inbound data.

4.1.20.6 View Graphs One of the most powerful features of Tomato, this allows you to view (in near-real-time) the current outbound connections and how the QoS engine is classifying them. This allows you to view how effective your QoS settings are, and whether they are capturing the connections you want them to. Simply click on any of the classes to view the list of specific connections for that class. 295

4.1.20.7 View Details Lists each connection that has recently been made through the router, and what QoS class was assigned to that connection. Clicking any entry will attempt to do a reverse lookup on the destination TCP/IP address, or you can click on the "automatically resolve addresses" checkbox at the bottom of the list to resolve all addresses in the list (this can take a while).

4.1.20.8

Access Restriction

Set time, computer, and protocol based bans on Internet access.

4.1.21 Administration

4.1.21.1 Admin Access Controls the various means that can be used to access the router for administrative purposes. All services use the same password, which is changed at the bottom of this page.

4.1.21.2 Web Admin Controls access to the router via a web browser. The web username may be "admin" or "root".

4.1.21.3 Local Access: Determines whether and how the router may be accessed from a web browser on a local computer (a computer attached to the router, or attached to a switch or hub attached to the router). Access can be via HTTP (regular web), HTTPS (SSL-encrypted web), both, or disabled. Remote Access: Determines whether and how the router may be accessed from a web browser from the WAN (Internet) side of the router. It is not recommended that this be enabled, and if it must be enabled, consider using the HTTPS method, which at least encrypts your session data. 296

Allow Wireless Access: If checked, wireless clients on your local network can access your router's administration screens using the same method as wired clients. This has no effect on Remote Access.

4.1.21.4

Bandwidth Monitoring

The bandwidth monitor history is just bandwidth data that can be viewed at the Bandwidth page of the Tomato UI.

4.1.21.5 Namely WAN port monthly history, WAN port daily history for the current month and intraday history (for vlan1, eth1, br0, eth0 & vlan0) captured over the last 24 hours. For this reason the backup file does not grow in size once it has reached about 133 Bytes.

4.1.21.6 Enable: check to enable / uncheck to disable

4.1.21.7 Save Frequency: Select an interval for periodic saving of bandwidth usage history. Useful if your router experiences power outages from time to time.

4.1.21.8 Save On Shutdown: Cause a save before any reboot or shutdown event but obviously not before a power outage!

4.1.21.9 Create New File / Reset Data: Check this when setting up a new Save History Location. When checked a new file is created in the save location. If the file already exists in the save location all current data will be overwritten!

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4.1.21.10 First Day Of The Month: Used to align the monthly data to the same accounting cycle that your ISP uses.

4.1.21.11 Excluded Interfaces: Comma separated list of Interfaces to exclude from the 24 Hours and Real Time Bandwidth pages of the Tomato UI. ( Example: vlan0,vlan1,eth0 will leave focus on the wireless LAN interface.) This has no appreciable effect on size of the history backup file being saved.

vlan1: wired WAN port vlan0: wired LAN ports eth1: Wireless LAN br0: internal LAN bridge (configurable) for wired LAN and Wireless LAN eth0: internal interface between CPU and the 6-port switch

4.1.21.12 Buttons / LED Change the action performed by the button. Different actions can be set for different lengths of time the button is held down (Count the DMZ blinks). The default actions are (1) tap to toggle wireless and (2) hold 20 seconds to start telnet on port 233.

4.1.21.13 Configuration Allows you to back up all your settings to your PC, restore them, or reset the router to factory defaults.

4.1.21.14 Avoid displaying LAN to router connections: If checked, LAN to router connections are not displayed on the QOS pages. If not checked, LAN to router connections are displayed on the QOS pages as "Unclassified" connections. There is generally a factory reset option (in Tomato, this is located under Administration/Configuration/Restore Default Configuration

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4.1.22:Reboot... Restarts the router (without erasing any settings).

4.1.23:Shutdown...Turns the router off (controlled shutdown)

4.1.24:Logout Logs you out of the firmware (clears your user session). This will dump you back to the initial login, where you are asked to present your credentials again (which causes occasional confusion, with people reporting that they "need to log in in order to log out").

Figure 4.1:Tomato device list

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Figure 4.2:QOS- BASIC SETTINGS

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Figure 4.3:STATUS - OVERVIEW

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Figure 4.4:BANDWIDTH- REAL TIME(br0)

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Figure 4.5:Bandwidth- Real Time- br0

4.1.25:Features Interactive Ajax based GUI using SVG and CSS-based color schemes (allowing GUI look and feel changes). DHCP server. DNS forwarder (using Dnsmasq). Netfilter/iptables with customizable settings, IPP2P and l7-filter. Advanced QoS: 10 unique QoS classes defined, real-time graphs display prioritized traffic with traffic class details. Bandwidth graphing/statistics. 303

Wireless modes: o

Access point (AP)

o

Wireless client station (STA)

o

Wireless ethernet (WET) bridge

o

Wireless distribution system (WDS aka wireless bridging)

o

Simultaneous AP and WDS (aka wireless repeating).

Wireless LAN Radio power of adjustement , antenna selection, and 14 wireless channels. 'Boot wait' protection (increase the time slot for uploading firmware via the boot loader). Advanced port forwarding, redirection, and triggering with UPnP. Advanced user access restrictions. Init, Shutdown, Firewall, and WAN Up scripts. Uptime, load average, and free memory status. Minimal reboots - Very few configuration changes require a reboot. Wireless survey page to view other networks in your neighborhood.

4.2 FREIFUNK Once the Linksys firmware has been upgraded to the Freifunk firmware we can start the configuration of the mesh node. As indicated before the following settings need to be configured: _ System settings _ Wireless settings _ LAN settings _ OLSR settings

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Figure 4.6: Configuration of a mesh node

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Figure 4.7:SETTING UP ADMINISTRATION SETTINGS

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Figure 4.8:Setting up freifunk firmware for wireless

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4.3 OPEN WRT OpenWrt is a Linux-based firmware program for embedded devices such as residential gateways. Support was originally limited to the Linksys WRT54G series, but has since been expanded to include other chipsets and manufacturers, including x86. The most popular routers seem to be the Linksys WRT54G series and the Asus WL500G. OpenWrt primarily uses a command-line interface, but also features an optional web-based GUI interface. Technical support is provided through the forums and IRC channel.

Figure 4.9:STATUS-router

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Figure 4.10 Basic setting

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Figure 4.11:SETUP-Advanced Routing

The development of OpenWrt was initially aided by the ease of modification afforded by manufacturers' use of software licensed under the GNU General Public License (GPL), which requires manufacturers to release all changes made to code originally licensed under the GPL. Initially using this as a base and later as a reference, developers created a distribution that offers many features not previously found in consumer-level routers.

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APPLICATION DEVELOPMENT FOR WMN

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CHAPTER 1

WIRELESS MESH NETWORK DEPLOYED IN SMIT

1.1. INTRODUCTION The wireless mesh network that has been placed in the SMIT for testing purposes has been done with the help of four (4) WRT54GL routers. The routers were connected to each other in a chain i.e. the Router ‗A‘ had the internet connection fed to it and its configuration parameters for linking with other devices was assigned for linking with the Router ‗B‘. For the Router ‗B‘ the link was assigned to router ‗C‘ and the link from router ‗C‘ the link was assigned to router ‗D‘. Thus the Router ‗A‘ serves the Gateway for internet and the connectivity for the entire Mesh Network built on the 4 routers.

1.2. ROUTER CONFIGURATION PARAMETERS 1.2.1 Router ‘A’ The WAN has to be configured to Manual Mode. The IP address of the router is assigned as 192.168.1.1 The DHCP server is Enabled The Wireless Mode is Access Point + WDS The SSID is assigned as samessid The Channel is given as 3 The WDS mode being Link with… and the MAC address of the Router ‗B‘ is assigned. 1.2.2 Router ‘B’ The WAN has to be configured to Disabled Mode. The IP address of the router is assigned as 192.168.1.2 The DHCP server is Disabled 312

The Wireless Mode is Access Point + WDS The SSID is assigned as samessid (it means that we need to have the same SSID Name as the Router ‗A‘) The Channel is given as 3 (Its means that we need to have the same Channel as the Router ‗A‘) The WDS mode being Link with… and the MAC address of the Router ‗A‘ and Router ‗B‘ is assigned. 1.2.3 Router ‘C’ The WAN has to be configured to Disabled Mode. The IP address of the router is assigned as 192.168.1.3 The DHCP server is Disabled The Wireless Mode is Access Point + WDS The SSID is assigned as samessid (it means that we need to have the same SSID Name as the Router ‗A‘) The Channel is given as 3 (Its means that we need to have the same Channel as the Router ‗A‘) The WDS mode being Link with… and the MAC address of the Router ‗B‘ and Router ‗D‘ is assigned.

1.2.4 Router ‘D’ The WAN has to be configured to Disabled Mode. The IP address of the router is assigned as 192.168.1.1 The DHCP server is Disabled The Wireless Mode is Access Point + WDS The SSID is assigned as samessid (it means that we need to have the same SSID Name as the Router ‗A‘) The Channel is given as 3 (Its means that we need to have the same Channel as the Router ‗A‘) The WDS mode being Link with… and the MAC address of the Router ‗C‘ is assigned. 313

1.3 . THE PRACTICAL EXPERIMENT CONDUCTED ON THE ROOF TOP For the conduction of the experiment we used four routers as mentioned in the previous part. The Router ‗A‘ that serves as the gateway to the entire mesh network internet was given through the LAN wire. It was placed at the 2nd level outside the BBCN lab window facing the ―A‖ Quadrangle. The 2nd Router is placed on the roof top close to the edge of the roof so that the router ‗A‘ and the router ‗B‘ have a Line Of Sight (LOS) contact. The 3rd router is placed on an elevated platform pointed towards the Dish placed on the roof top. Although the router ‗A‘ and router ‗B‘ have omni-directional antennas, the 3rd router has one omni-directional antenna and a Horn antenna. The omni-directional antenna is used for the interaction of router ‗C‘ with router ‗B‘ and the horn antenna is used to focus the antenna beam on the dish to improve its gain and also to focus it highly so that the beam can be transmitted to the router ‗D‘ that is placed on the roof above E quadrangle. The router ‗D‘ has two omni-directional antennas. The beam has to be focused by changing the parameters that affect the beam i.e. the direction of the horn, the elevation of the dish, the angle of the dish with LOS for router ‘D‘. The SNR value needs to be monitored at every instant so that we get the maximum quality of the signal. The monitoring of the SNR was done with the help of the Wireless Survey option in the Tomato Firmware. We could achieve a maximum SNR value of -69 dBm and a quality of 30% signal. After this we placed a computer in the BBCN lab that was connected to the router ‗A‘. Another laptop was placed in the vicinity of the router ‗C‘ and another computer was placed connected to the router ‗D‘. This system was used to test the multimedia Transmission, Chat and Voice over Internet Protocol (VoIP).

CHAPTER 2 314

MULTIMEDIA TRANSMISSION

2.1. MULTIMEDIA TRANSMISSION The multimedia transmission was developed in two parts i.e.

2.1.1 Point to Point Transmission:

Fig 2.1. Multimedia Transmission via UDP port involving both Video and Audio

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The Multimedia File block is used to open a multimedia file that consists of both Video and Audio component. Here we can define the characteristics of the file i.e. whether we want to have only Video Transmission or Audio Transmission or Both Audio and Video Transmission. We can also indicate the end of file by opening the window that defines the block. The file that needs to be transmitted can be selected by browsing the file from the block.The output of the file‘s Video component has been specified in RGB format. We can also specify the data type of both Video and Audio. The Video data from this block is sent to the Color Space Conversion Block where the RGB format of the Video is converted to Y‘CbCr format. The Color Space Conversion block converts color information between color spaces. One can use the Conversion parameter to specify the color spaces you are converting between. Your choices are R'G'B' to Y'CbCr, Y'CbCr to R'G'B', R'G'B' to intensity, R'G'B' to HSV, HSV to R'G'B', sR'G'B' to XYZ, XYZ to sR'G'B', sR'G'B' to L*a*b*, and L*a*b* to sR'G'B'. The conversion selected by us is RGB to Y‘CbCr as we can further compress the video data using Chroma Resampling as per our requirements and conditions of the system. After this we use Chroma Resampling to downconvert the Chrominance component of the video data being used. Here we have used the 4:4:4 to 4:2:2(MPEG2) conversion where the no of pixels or elements per frame for the Chrominance component is decreased by half for both Cb and Cr. After this we use a byte pack block that is used to align the elements of the video data in a single vector of data type unit8. This helps in sending the video data that has now been packed to be transmitted over the UDP Port. In the UDP send Block we need to mention the ip address and the port number of the receiver so that effective data transmission can occur between the Transmitter and the Receiver. We can assign the ip address as 255.255.255.255 if the destination is not known. This address is also the default address and also is used to indicate that the data needs to transmitted to any address that accepts the data. For the Audio component of the multimedia file we need a UDP send block that is different from the one used for Video data. Also we need to unbuffer the streamed audio before it can be transmitted through the UDP port. For the receiver we have a UDP receive block that is used to the data from the ip address as mentioned in its parameters. Here we also need to mention the port and also the buffer size for the data that is being received. If the address for the transmitter is not known then 316

we can assign an ip address of 0.0.0.0 which is also the default for the UDP block. It signifies that the block would receive data from any source that is broadcasting. After receiving the video data we use byte unpack block that convert a singular vector to the size as mentioned in the block. The vector newly formed can be two or three dimensional as per the initial condition. This vector formed is of the compressed Y‘CbCr format which is decompressed using Chroma resampling of type 4:2:2(MPEG2) to 4:4:4.this block upconverts the Chrominance component that was downsampled in the transmitter. After this block the uncompressed Video data is sent to Color Space Conversion model where we convert the data from Y‘CbCr format to RGB format which is same as the original uncompressed Video data. This data is then given to the Video Viewer so that the received video can be that have been streaming the UDP ports can be watched easily. For the audio portion of the data that was transmitted we have another UDP receive that receives the audio data. This received data is then passed through the buffer block where buffering of the data is done so that Audio in its initial form can be obtained. This is then given to a Audio Device where we can listen to the synchronized Audio data through the speakers that are connected to the Computer. This was accomplished with laptop connected to the Router ‗C‘ as the Transmitter and the computer connected to Router ‗D‘ as the Receiver. The default video present in the Matlab software was used for transmission and the same was received at the receiver. The frame rate was very close to the original frame rate of the video that was being transmitted. The naked eye could not detect any changes in the frame rate or the deteriorated quality of the multimedia that was transmitted. The same system was also tested with the computer connected to Router ‗A‘ as the transmitter and the laptop connected to the router ‗C‘ as the receiver. The results in this case too were similar to the one that were obtained in the previous one.

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2.1.2 Multimedia Broadcasting And Multicasting System (MBMS)

Fig 2.2 :Transmitter Model for MBMS for video only

The transmitter model for MBMS is different from the model for one to one transmission. Here the Multimedia File block is used to open a multimedia file that consists of both Video and Audio component. Here we can define the characteristics of the file i.e. whether we want to have only Video Transmission or Audio Transmission or Both Audio and Video Transmission. We can also indicate the end of file by opening the window that defines the block. The file that needs to be transmitted can be selected by browsing the file from the block. The output of the file‘s Video component has been specified in RGB format. We can also specify the data type for both Audio and Video. We also use an Time based Entity Generator that generates an entity based on the frequency that is assigned in the block. Here we choose to generate the entities from the start of the 318

simulation only. The entity is used to pack the information assigned to it in the Set Attribute block. Since the information needs to be packed so the frequency of generation of entity is same as the frame rate of the Video that needs to be transmitted. In the Set Attribute block we have assigned 3 input signals, all of which are considered as 1-D vector. The output of the block is an entity that contains the information of the RGB components of the each video frame that is being transmitted. After this the entities are queued up in a FIFO queue so that the different output ports have no delay in receiving the data. After the queue block we use a Replicate block that is used to replicate or make copies of the input entity that can be use by different ports for data transmission. After this we use a Release Gate that is used to release the entities at proper intervals. The intervals are based on the product of the flow control and sample signal. The flow control defines the time after which the first entity is sent and the sample signal controls the rate of entity transmission. After the Release gate allows the entity from to be transmitted the entity is sent to the Get Attribute block where the packed data of the entity is retrieved and the different RGB components of the video data are given out as signals. The newly emptied entity is then sent to entity sink where the entity dies out. For the RGB signal we now do the required processing in Resampling block before it can be sent to the client through the UDP Send block. The Video data from Get Attribute block is sent to the Color Space Conversion Block where the RGB format of the Video is converted to Y‘CbCr format. The Color Space Conversion block converts color information between color spaces. One can use the Conversion parameter to specify the color spaces you are converting between. Your choices are R'G'B' to Y'CbCr, Y'CbCr to R'G'B', R'G'B' to intensity, R'G'B' to HSV, HSV to R'G'B', sR'G'B' to XYZ, XYZ to sR'G'B', sR'G'B' to L*a*b*, and L*a*b* to sR'G'B'. The conversion selected by us is RGB to Y‘CbCr as we can further compress the video data using Chroma Resampling as per our requirements and conditions of the system. After this we use Chroma Resampling to downconvert the Chrominance component of the video data being used. Here we have used the 4:4:4 to 4:2:2(MPEG2) conversion where the number of pixels or elements per frame for the Chrominance component is decreased by half for both Cb and Cr. After this we use a byte pack block that is used to align the elements of the video data in a single vector of data type unit8. This helps in sending the video data that has now been packed to be 319

transmitted over the UDP Port. In the UDP send Block we need to mention the ip address and the port number of the receiver so that effective data transmission can occur between the Transmitter and the Receiver. We can assign the IP address as 255.255.255.255 if the destination is not known. This address is also the default address and also is used to indicate that the data needs to transmitted to any address that accepts the data.

Fig 2.3: Transmitter for MBMS for both Audio and Video

This model is very similar to the previous transmitter where only Video data was being transmitted. The audio component of any multimedia data before being stored in the entity needed to be unbuffered so we placed an unbuffer Block at the audio output of the 320

multimedia file. After this we added an extra signal naming it as audio in the Set Attribute block. At the Get Attribute was added so that the audio component could be extracted from the entity. After this the audio component was sent to a different UDP Send block for transmission. Rest all the blocks and their functions were similar to the modal that was explained previously. The Receiver of the model was similar to the receiver of the model for Point to Point Communication. The only difference being that different ip addresses were assigned for receiving in the receiver model. These models were used for broadcasting the multimedia data over to several computer or clients at any instant of time. To conduct this experiment we maintained the system as mentioned above and the computer connected to router ‗A‘ was made the Transmitter. The multimedia data was being transmitted with help of the above model to 3 clients connected on the network including the computer that was serving as the transmitter. The video received at the computer connected to the router ‗A‘ was very much similar to the original video but the multimedia data that was being received at the other two computers needed buffering. The frames that were being received had a very low frame rate thus the video used to hang for certain time till the data that was being received as it uses this time to buffer. Also the quality of the video is deteriorated to a great extent. Thus we deduced that the video transmission over mesh networks suffers a great deal. A method to eradicate this problem is to use a model where the received video data is stored and thus we can access the video at a later time so that we don‘t come across the problem of low frame rate or buffering of multimedia data.

Another thing that needed to be kept in mind was only the authorized clients could gain access to the data so we needed an authorization or a key that could control the flow of data to different clients. The model with this feature is explained below. The problem with this model is that any client whose has access to the numerical key could access the data that was being transmitted. Although we needed an option where the key for authorization could be sent along with the data but we found it difficult to inculcate it in the model. So we gave access to the client to input the key to the s-function and based on that the data could be received. 321

Fig 2.4: Receiver of Multimedia communication (VIDEO + AUDIO) with Key for authentication

This is a special case of receiver where the receiver or the client needs to fill the correct key before it can gain access to the multimedia data that is being broadcasted. For this we have placed a UDP receive block that is used to receive the singular vector from the channel through which the multimedia data is sent. The block is used to the data from the ip address as mentioned in its parameters. Here we also need to mention the port and also the buffer size for the data that is being received. If the address for the transmitter is not 322

known then we can assign an ip address of 0.0.0.0 which is also the default for the UDP block. It signifies that the block would receive data from any source that is broadcasting. This is given to a 2-input switch which has as its select line an S-function that takes the input of the numeral which is considered as the key. Depending on this input the sfunction gives an output of zero (0) or non-zero(preferably 1). The other input of the switch being a default image file stored in the client‘s computer that reads DATA NOT FOUND. An important thing to be considered for the s-function is that we need to have a proper combination of inputs and outputs and also that they are defined properly. We also need to build the s-function by using the command mex –setup on the command line and then follow the instruction so that Matlab can access a existing builder. For the switch we need to take into consideration the frequency of operation of the switch and also the size of the frame of the input video should match the frame of the image being used when the key input to the system is wrong. After receiving the video data we use byte unpack block that convert a singular vector to the size as mentioned in the block. The vector newly formed can be two or three dimensional as per the initial condition. This vector formed is of the compressed Y‘CbCr format which is decompressed using Chroma resampling of type 4:2:2(MPEG2) to 4:4:4.this block upconverts the Chrominance component that was downsampled in the transmitter. After this block the uncompressed Video data is sent to Color Space Conversion model where we convert the data from Y‘CbCr format to RGB format which is same as the original uncompressed Video data. This data is then given to the Video Viewer so that the received video can be that have been streaming the UDP ports can be watched easily. For the audio component also we need to take into consideration that the switch‘s operating frequency is matched with the 2 inputs to the switch. Also we need to consider that the frequency of the default audio matches that of the input audio for the source. Here also we use a UDP receive block to receive the audio component of the multimedia data that is being transmitted. Since we have used a s-function where we have two outputs so the other output is used to as the select line for switch1 that is the switching device for audio component. After the switch we use a buffer so that we can buffer up the frames of the audio device and thus the audio data can be listened to through the audio sink and is also synchronized with the Video.

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The problem that we face here is that firstly we need to have the same frame size of the image that reads DATA NOT FOUND to the frame size of the input video from the UDP port. Another problem is that we need to use the default audio data which has the same frequency as the audio data that has been received through the UDP port. Also we need to build the s-function every time the model is closed and then opened again. The performance of the block is also not optimized as the frame rate of the video data that is received is lower than the actual rate and also the quality of the audio data is poor as it has several gaps in the entire data.

2.2. CHAT The chat feature was inculcated with the help of a program which was made in .m file mode for Matlab.

2.2.1 Program For Chat Application u2 = udp('192.168.1.1',9211,'localport',9210); u2 get(u2,'status') fopen(u2); get(u2,'status') set(u2,'timeout',2); first = 'SEND MESSAGE'; second = 'CONTINUE'; third = 'EXIT'; nomsg = ''; while (1) { fscanf(u2); fscanf(u2); if isequal(ans,nomsg) ; 324

else h = msgbox(ans,'MESSAGE RECEIVED','help'); end button

=

questdlg('DO

YOU

WISH

TO...','QUERY','SENDMESSAGE','CONTINUE' ,'EXIT','CONTINUE');

if isequal(button,first) prompt = {'ENTER MESSAGE :'}; title = 'CHAT'; num_lines =1; answer = inputdlg(prompt,title,num_lines); answ=char(answer); fprintf(u2,answ); elseif isequal(button,second) j=1 while(j<5) fscanf(u2); if isequal(ans,nomsg) j=j+1; continue; else h = msgbox(ans,'MESSAGE RECEIVED','help'); break; end end if (j>4) h = helpdlg('NO MESSAGE HAS BEEN RECEIVED','DATA NOT FOUND') for i=1:100000 continue; 325

i end end elseif isequal(button,third) break; end3 end fclose(u2) get(u2,'status') delete(u2)

For the m-file for chat to work properly we firstly need to create a UDP object. It is created bY using an inbuilt Matlab function ―udp‖. the parameters for the function are the ip of the destination client with whom the chat needs to be started.we also need to mention the port of the destination client that will receive the data and also the port from where the data will be sent.then to confirm that the object has been created we again use the name of the craeted object without a colon. After this we check the status of the object as to whether it is closed or open. After this we use ―fopen‖ to open the ceated object so that the communication can be established. Now again the staus of the object is checked to confirm if the object is now open or closed. Now we use the ―set‖ to change the timeout property of the object.this enables to decrease or increase the time for which the fscanf function will scan for a data if any has been sent from the other client. we now assisn different strings like ‗SEND MESSAGE‘, ‗CONTINUE‘, ‗EXIT‘,‘ ‘ to variables like ‗FIRST‘, ‗SECOND‘, ‗THIRD‘ and ‘nomsg‘. After this we use an infinite loop where we continually ask the user to choose between option of sending message or waiting to receive any message or exit from the chat program. In the starting of the loop we use two fscanf functions. If a message is received then a box is shown displaying a message else the query as mentioned above is shown. Depending upon the choice mentioned by the user we can have three options. Firstly the user can send message, for which a text block is displayed showing a place where the message to be sent can be 326

entered. We can also change the number of lines that are displayed in the text box. Now the user can enter the text that it wishes to transmit. As the OK is pressed the fprintf function can be used to send the message to the destination mentioning the name of the UDP object and the message that was given as input by the user. The different parameters that are specified for the text box are the title which is CHAT, the prompt message which is ENTER MESSAGE. We also use char function to convert the entered text to string that can be sent to the destination. The second option that the user has is for waiting for some time so that it can check if a message has been received or not. If a message has been received then a box is displayed that has the message received with the heading MESSAGE RECEIVED. If no message has been received then a box is displayed stating that NO MESSAGE HAS BEEN RECEIVED. The third option is to exit out from the chat session. For exiting out of the chat session we need to exit from the infinite loop using the break statement. after this we close the UDP object using fclose function. After this the status of the object is checked again. Now the object is deleted using delete function. We now use clear function to remove all the traces of the object that was created so that the port assigned for chatting is rendered free. The problem that we faced here was that when the computers are connected and the chat is in session, we sometimes loose the data that is transmitted. This is because of the use of UDP protocol. We tried to switch over the TCP/IP protocol but the options available for the later protocol in Matlab are limited. Also the displayed boxes showing the message received or data not found used to hang the system for a considerable period of time and also no delay could continue showing the same box after the system recovered from the Hanging condition. Also to make this program a Stand Alone application we needed to ask the client to enter the ip address and also the port of its own computer and the computer to which the communication is being established. Similarly the other client needed to enter the ip address of the first client and the mentioning of the port address in the same manner as the former client had done. This becomes a very tedious task to accomplish as any mistake in any of the entries made by any of the client would lead to failure of the Chat application.

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2.3.VOICE OVER INTERNET PROTOCOL (VoIP) Voice-over-Internet protocol (VoIP) is a protocol optimized for the transmission of voice through the Internet or other packet-switched networks. VoIP is often used abstractly to refer to the actual transmission of voice (rather than the protocol implementing it). This latter concept is also referred to as IP telephony, Internet telephony, voice over broadband, broadband telephony, and broadband phone. The last two are arguably incorrect because telephone-quality voice communications are, by definition, narrowband. Because UDP does not provide a mechanism to ensure that data packets are delivered in sequential order, or provide Quality of Service (QoS) guarantees, VoIP implementations face problems dealing with latency and jitter. This is especially true when satellite circuits are involved, due to long round-trip propagation delay (400–600 milliseconds for links through geostationary satellites). The receiving node must restructure IP packets that may be out of order, delayed or missing, while ensuring that the audio stream maintains a proper time consistency. This function is usually accomplished by means of a jitter buffer in the voice engine. VoIP uses SIP protocol for voice transmission. The Session Initiation Protocol (SIP) is a signaling protocol, widely used for setting up and tearing down multimedia communication sessions such as voice and video calls over the Internet. Other feasible application examples include video conferencing, streaming multimedia distribution, instant messaging, presence information and online games.

2.3.1 VoIP Challenges: Available bandwidth Network Latency Packet loss 328

Jitter Echo Security Reliability In rare cases, decoding of pulse dialing Testing and deploying the VoIP over wireless mesh network was a challenge. This feature is a client to client based and was done in two parts i.e. Intranet and Internet We tested the network for VOIP using Windows NetMeeting and LAN voice chat. The voice quality was superb and crystal clear using NetMeeting. Whereas when the VoIP was established with LAN chat, it gave a good voice transmission but jitters were prominent. We also tried to establish VOIP communication by connecting a Lenovo laptop to the Router in the Mesh Network, but the Vista did not support either NetMeeting or LAN chat or its inbuilt network meeting space. The snapshot of the NetMeeting is shown below that was used for accomplishing the VoIP over the Network.

Fig 2.5: The VoIP Interface

329

2.4 INTARNET: This was tested with all the possible chat sessions between the three computers that were connected to the mesh network. The quality of audio data was very good in all the cases. Also the delay for the audio transmission was very low of the order of few milliseconds. This was achieved with the help of Microsoft NetMeeting. The call was placed from NetMeeting of a computer to the NetMeeting of another computer. After the call was accepted the voice chat could be done easily. The same was tried using the model for

330

audio transmission and reception but here even though the voice transmitted was received at the receiver, the noise level was very high and thus the voice wasn‘t received instead an audible noise was heard whenever the voice data was transmitted.

2.5. INTERNET Here the internet was made available to router ‗A‘ and thus the entire network has the access to internet. After logging onto the internet chat session was launched using the Google Chat and Skype. Entire process was tested for all the different configurations. This was achieved successfully and the quality of voice was also very good. Although the delay in the voice was considerable but it is still very low to be taken into consideration.

CHAPTER 3 331

GRAPHICAL USER INTERFACE (GUI)

3.1. GRAPHICAL USER INTERFACE:

A graphical user interface (GUI) is a graphical display that contains devices, or components, that enable a user to perform interactive tasks. The GUI components can be menus, toolbars, push buttons, radio buttons, list boxes, and sliders -- just to name a few. In MATLAB, a GUI can also display data in tabular form or as plots, and can group related components

Fig3.1: A simple GUI

3.1.1 How Does A GUI Work:

332

Each component, and the GUI itself, is associated with one or more user-written routines known as callbacks. The execution of each callback is triggered by a particular user action such as a button push, mouse click, selection of a menu item, or the cursor passing over a component. You, as the creator of the GUI, provide these callbacks.This kind of programming is often referred to as event-driven programming. In event-driven programming, callback execution is asynchronous, controlled by events external to the software. In the case of MATLAB GUIs, these events usually take the form of user interactions with the GUI.

3.1.2 What is a Callback?

A callback is a function that you write and associate with a specific component in the GUI or with the GUI figure itself. The callbacks controls GUI or component behavior by performing some action in response to an event for its component. The event can be a mouse click on a push button, menu selection, key press, etcWhen an event occurs for a component, MATLAB invokes the component's callback that is associated with that event. As an example, suppose a GUI has a push button that triggers the plotting of some data. When the user clicks the button, MATLAB calls the callback you associated with clicking that button, and then the callback, which you have programmed, gets the data and plots it.

3.2 GUIDE: a brief introduction

GUIDE, the MATLAB graphical user interface development environment, provides a set of tools for creating graphical user interfaces (GUI). These tools simplify the process of laying out and programming GUIs.

333

Lay out the GUI: .Using the GUIDE Layout Editor, we can lay out a GUI easily by clicking and dragging GUI components—such as panels, buttons, text fields, sliders, menus, and so on—into the layout area. GUIDE stores the GUI layout in a FIG-file. Program the GUI.:GUIDE automatically generates an M-file that controls how the GUI operates. The M-file initializes the GUI and contains a framework for the most commonly used callbacks for each component—the commands that execute when a user clicks a GUI component. Using the M-file editor, we can add code to the callbacks to perform the functions you want.

3.3. PROGRAMMING THE GUI:

When we save the GUI layout, GUIDE automatically creates an M-file that controls the working of the GUI. This M-file provides code to initialize the GUI.and contains a framework for GUI callback. Using M- file editor we can add code to the callback to perform the desired functions. Detailed functions related to programming of GUI are explained later.

3.4. LAYING OUT A SIMPLE GUI:

3.4.1 Opening a new GUI in Layout Editor: 1. GUIDE can be started by typing guide at the matlab command prompt. This displays the GUIDE Quick Start dialog box as shown below:

334

Fig 3.2: opening the GUI

2. In the Quick Start Dialog Box , we select Blank GUI(Default) template. This displays a blank GUI in the Layout Editor.

335

Fig 3.3: a blank GUI(Default)

4. Display the names of the GUI components in the component palette. Select Preferences from the MATLAB File menu. Then select GUIDE > Show names in component palette, and click OK. The Layout Editor then appears as shown in the following figure.

Fig 3.4: different GUI components 336

3.4.2 The Layout Editor: When we open a GUI in GUIDE, it is displayed in the Layout Editor, which is the control panel for all of the GUIDE tools. The following figure shows the Layout Editor with a blank GUI template.

Fig 3.5: the layout area

337

We can lay out your GUI by dragging components, such as panels, push buttons, pop-up menus, or axes, from the component palette, at the left side of the Layout Editor, into the layout area. For example, if we drag a push button into the layout area, it appears as in the following figure.

Fig 3.6: push button in a GUI

338

3.4.3 Completed Layout: In the Layout Editor, your GUI now looks like this after adding all the required components and editing and aligning the required components. The next step is to save the layout

339

Fig 3.7: A completed GUI layout

3.5. SAVING THE GUI LAYOUT :

When we save a GUI, GUIDE creates two files, a FIG-file and an M-file. The FIG-file, with extension .fig, is a binary file that contains a description of the layout. The M-file, with extension .m, contains the code that controls the GUI.

1. Save and activate your GUI by selecting Run from the Tools menu 2. GUIDE displays the following dialog box. Click Yes to continue.

340

Fig 3.8: dialog box while saving GUI

3. GUIDE opens a Save As dialog box in your current directory and prompts you for a FIGfile name.

Fig 3.9: the Save As dialog box

4. Browse to any directory for which you have write privileges, and then enter the filename 341

simple_gui for the FIG-file. GUIDE saves both the FIG-file and the M-file using this name. 5. If the directory in which we save the GUI is not on the MATLAB path, GUIDE opens a dialog box, giving you the option of changing the current working directory to the directory containing the GUI files, or adding that directory to the top or bottom of the MATLAB path.

Fig 3.10: dialog box to change current working directory

6. GUIDE saves the files simple_gui.fig and simple_gui.m and activates the GUI. It also opens the GUI M-file in your default editor. The GUI is active. You can select a data set in the pop-up menu and click the push buttons. But nothing happens. This is because there is no code in the M-file to service the pop-up menu and the buttons.

342

Fig 3.11: A completed GUI

3.6. ILLUSTARTION OF A SIMPLE GUI: The figure below shows a simple GUI that we have developed. The ‗open image file‘ tab opens an image file when the push button is pressed. The button group having ‗webview simulink model‘, ‗video file‘, ‗internet—Google‘ and ‗open simulink tab‘.

Fig 3.12: GUIDE

343

Fig 3.13: Completed GUI 344

3.6.1 Buttons In The GUI:

a) Open Image File: This tab opens an image file which is present in the MATLAB work directory. Syntax: filename=uigetfile(‘*.jpg’); imshow(imread(filename)); b)Video File : this button runs a video file Syntax: mplay(*.avi)

Fig 3.14: The video file 345

c) Internet : ‗web‘ is the default command for opening an internet explorer in MATLAB. Syntax: web (‘www.mathworks.com’)

Fig 3.15: The internet explorer webpage

346

d) Open A Simulink Model : this push button displays a specified simulink model which is present in the simulink library Syntax: filename_m=uigetfile(‘*.mdl’) open(filename_m)

Fig 3.16: The opened simulink model

347

e) Windows Explorer : opens the windows explorer Syntax:[s,w]=system(‘explorer.exe’);

Fig 3.17: The windows explorer 348

f) Notepad : this push button in the GUI shows directly opens the notepad. Syntax: [s,w]=system(‘notepad’);

Fig 3.18: The notepad

349

g) Netmeeting (Activex Application): netmeeting is a VoIP and is used for multipoint video conferencing.

Fig 3.19: Windows Netmeeting Application

3.7. M Code Of The Above GUI: 350

function varargout = GUI_figure(varargin) % GUI_FIGURE M-file for GUI_figure.fig %

GUI_FIGURE, by itself, creates a new GUI_FIGURE or raises the existing

%

singleton*.

%

H = GUI_FIGURE returns the handle to a new GUI_FIGURE or the handle to

%

the existing singleton*.

% %

GUI_FIGURE('CALLBACK',hObject,eventData,handles,...) calls the local

%

function named CALLBACK in GUI_FIGURE.M with the given input arguments.

% %

GUI_FIGURE('Property','Value',...) creates a new GUI_FIGURE or raises the

%

existing singleton*. Starting from the left, property value pairs are

%

applied to the GUI before GUI_figure_OpeningFcn gets called. An

%

unrecognized property name or invalid value makes property application

%

stop. All inputs are passed to GUI_figure_OpeningFcn via varargin.

% %

*See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one

%

instance to run (singleton)".

% % See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help GUI_figure

% Last Modified by GUIDE v2.5 27-May-2008 11:48:21

% Begin initialization code - DO NOT EDIT gui_Singleton = 1; gui_State = struct('gui_Name',

mfilename, ...

'gui_Singleton', gui_Singleton, ... 351

'gui_OpeningFcn', @GUI_figure_OpeningFcn, ... 'gui_OutputFcn', @GUI_figure_OutputFcn, ... 'gui_LayoutFcn', [] , ... 'gui_Callback', []); if nargin && ischar(varargin{1}) gui_State.gui_Callback = str2func(varargin{1}); end

if nargout [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:}); else gui_mainfcn(gui_State, varargin{:}); end % End initialization code - DO NOT EDIT

% --- Executes just before GUI_figure is made visible. function GUI_figure_OpeningFcn(hObject, eventdata, handles, varargin) % This function has no output args, see OutputFcn. % hObject

handle to figure

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

% varargin command line arguments to GUI_figure (see VARARGIN)

% Choose default command line output for GUI_figure handles.output = hObject;

% Update handles structure guidata(hObject, handles);

% UIWAIT makes GUI_figure wait for user response (see UIRESUME) 352

% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line. function varargout = GUI_figure_OutputFcn(hObject, eventdata, handles) % varargout cell array for returning output args (see VARARGOUT); % hObject

handle to figure

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure varargout{1} = handles.output;

% --- Executes on button press in pushbutton1. function pushbutton1_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton1 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

filename=uigetfile('*.jpg') imshow(imread(filename));

% --- Executes on button press in pushbutton2. function pushbutton2_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton2 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

winopen('sldemo_f14_slwebview.html');

353

% --- Executes on button press in pushbutton3. function pushbutton3_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton3 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

web('www.google.com')

% --- Executes on button press in pushbutton4. function pushbutton4_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton4 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

mplay('barcodes.avi')

function edit1_Callback(hObject, eventdata, handles) % hObject

handle to edit1 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit1 as text %

str2double(get(hObject,'String')) returns contents of edit1 as a double

% --- Executes during object creation, after setting all properties. function edit1_CreateFcn(hObject, eventdata, handles) % hObject

handle to edit1 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB 354

% handles

empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows. %

See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')) set(hObject,'BackgroundColor','white'); end

% --- Executes on button press in pushbutton5. function pushbutton5_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton5 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

[s,w]=system('notepad')

% --- Executes on button press in pushbutton6. function pushbutton6_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton6 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) [s,w]=system('explorer.exe');

% --- Executes on button press in pushbutton7. function pushbutton7_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton7 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB 355

% handles

structure with handles and user data (see GUIDATA)

filename_m= uigetfile('*.mdl') open(filename_m);

% -------------------------------------------------------------------function activex1_ConferenceStarted(hObject, eventdata, handles) % hObject

handle to activex1 (see GCBO)

% eventdata structure with parameters passed to COM event listener % handles

structure with handles and user data (see GUIDATA)

% --- Executes on button press in pushbutton8. function pushbutton8_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton8 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

% --- Executes on button press in pushbutton9. function pushbutton9_Callback(hObject, eventdata, handles) % hObject

handle to pushbutton9 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB % handles

structure with handles and user data (see GUIDATA)

3.8. SOME OF THE FREQUENTLY USED COMMANDS IN GUIS: a) mplay:

we use the MPlay GUI to view video from files or the MATLAB

356

workspace.We can also use it to view video signals in Simulink models. If the video contains audio, the GUI ignores it and plays only the video frames. Command line syntax:

Table 3.1: The mplay Command Line syntax

Fig 3.20: The mplay GUI

357

b) web: Opens website or file in Web browser or Help browser

syntax: web:

web

opens an empty MATLAB Web browser. The MATLAB Web browser

includes an address field where we can enter a URL, for example, to a Web site or file, a toolbar with common browser buttons, and a MATLAB desktop menu.

web url: web url displays the specified URL, url, in the MATLAB Web browser. Files up to 1.5MB in size display in the MATLAB Web browser, while larger files instead display in the default Web browser for the system. If url is located in the directory returned when you run docroot, the URL displays in the MATLAB Help browser instead of the MATLAB Web browser.

358

web url –new: web url -new displays the specified URL, url, in a new MATLAB Web browser. web url –notoolbar: web url -notoolbar displays the specified URL, url, in a MATLAB Web browser that does not include the toolbar and address field. If any MATLAB Web browsers are already open, also use the -new option; otherwise url displays in the browser that last had focus, regardless of its toolbar status. web url –noaddressbox: web url -noaddressbox displays the specified URL, url, in a MATLAB Web browser that does not include the address field. If any MATLAB Web browsers are already open, we also use the -new option; otherwise url displays in the browser that last had focus, regardless of its address field status. web url –helpbrowser: web url -helpbrowser displays the specified URL, url, in the MATLAB Help browser. web url –browser: web url -browser displays the default Web browser for the system and loads the file or Web site specified by the URL url in it. Generally, url specifies a local file or a Web site on the Internet. The URL can be in any form that the browser supports. On Windows and Macintosh, the default Web browser is determined by the operating system. On UNIX, the Web browser used is specified via docopt in the doccmd string.

web(...): web(...) is the functional form of web.

stat = web('url', '-browser'): stat = web('url', '-browser') runs web and returns the status of web to the variable stat.

Table 3.2: Description of ‗stat‘ Value 359

Example: when we run the command web http://www.mathtools.net , MATLAB displays the window shown below

Fig 3.21: Window on running the web command

c) uigetfile: Open standard dialog box for retrieving files.

360

Syntax: uigetfile: uigetfile displays a dialog box used to retrieve one or more files. The dialog box lists the files and directories in the current directory.

d) Profile: The profile function helps us debug and optimize M-files by tracking their execution time. For each function in the M-file, profile records information about execution time, number of calls, parent functions, child functions, code line hit count, and code line execution time.

To open the Profiler graphical user interface, we use the profile viewer syntax. Profile time is CPU time. The total time reported by the Profiler is not the same as the time reported using the tic and toc functions . To change options, stop profiling and then start or resume profiling with new options.

Syntax:

profile on: profile on starts the Profiler, clearing previously recorded profile statistics. profile on -detail level: profile on -detail level starts the Profiler, clearing previously recorded profile statistics, and specifies the set of functions we want to profile. The level applies to subsequent uses of profile or the Profiler, until you change it. profile on –history: profile on -history

starts the Profiler, clearing

previously recorded profile statistics, and records the exact sequence of function calls. The profile function records up to 10,000 function entry and exit events. For more than 10,000 events, profile continues to record other profile statistics, but not the sequence of calls. By default, the history option is not enabled. profile on -timer clock: profile on -timer clock

starts the Profiler,

clearing previously recorded profile statistics, and specifies the type of time to use. 361

profile off: profile off stops the Profiler. profile resume: profile resume restarts the Profiler without clearing previously recorded statistics. profile viewer: profile viewer stops the Profiler and displays the results in the Profiler window.

3.9 What Is Profiling?

Profiling is a way to measure where a program spends its time. Using the MATLAB Profiler, we can identify which functions in the code consume the most time. You can then determine why we are calling them and look for ways to minimize their use. It is often helpful to decide whether the number of times a particular function is called is reasonable. Because programs often have several layers, the code may not explicitly call the most time-consuming functions. Rather, functions within your code might be calling other timeconsuming functions that can be several layers down in the code. In this case it is important to determine which functions are responsible for such calls.

Profiling helps to uncover performance problems that can solved by Avoiding unnecessary computation, which can arise from oversight Changing your algorithm to avoid costly functions Avoiding recomputation by storing results for future use

3.10 Opening The Profiler: Select Desktop > Profiler from the MATLAB desktop. Click the Profiler button in the MATLAB desktop toolbar. With a file open in the MATLAB Editor/Debugger, select Tools > Open Profiler. 362

Select one or more statements in the Command History window, right-click to view the context menu, and choose Profile Code. Enter the following function in the Command Window: profile viewer

3.11 Running The Profiler: The following illustration summarizes the steps for profiling.

Fig 3.22: profiler window

3.12 Profiling a Graphical User Interface:

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We can also run the Profiler for an interface you created, such as one built using GUIDE. To profile a graphical user interface we follow the following steps:

1. In the Profiler, click Start Profiling. Make sure that no code appears in the Run this code field. 2. Start the graphical user interface. (If we do not want to include its startup process in the profile, do not perform step 1, until after we have started the graphical interface.) 3. Use the graphical interface. When you are finished, click Stop Profiling in the Profiler.The Profile Summary report appears in the Profiler.

3.13 Profile summary report: The Profile Summary report presents statistics about the overall execution of the function and provides summary statistics for each function called. Shown below is the profile summary report of the GUI shown in the figure above:

Fig 3.23: Profile summary report 364

3.14 . CONCLUSION: In the application layer, we worked on how to develop a graphical user interface (GUI). A graphical user interface (GUI) is a graphical display that contains devices, or components, that enable a user to perform interactive tasks. To perform these tasks, the user of the GUI does not have to create a script or type commands at the command line. Often, the user does not have to know the details of the task at hand.

We created various types of GUI with help of Matlab v.R2007b software. The various GUIs included: Excel link GUI Activex control GUI which included applications like netmeeting ,internet , e.t.c GUIs for opening various applications like paint, games, e.t.c 365

Excel link GUI could import excel data sheet from the user, draw various plots like contour, bar, line, chart e.t.c

Activex control GUI could open applications like netmeeting, internet, video files e.t.c

Another GUI was developed for opening small applications like windows games (free cell, solitaire e.t.c), paint, notepad, vlc media player and many such applications.

After compiling the GUI we could also make standalone application in the form of executable file. Hence, we could run the entire graphical user interface without the help of Matlab software. Thus, we essentially developed an application which can be deployed independent of platform.

We have been trying to develop other GUIs for simulink models. These graphical user interfaces would open a simulink model specified by the user and change the parameters of various blocks of the simulink model.

There were various limitations that we had to face during the development of different GUIs. For creating a more complex GUI with various functions we required a better knowledge of Matlab programming. Some of the inbuilt functions could not be converted into standalone applications. Time limitation was another factor.

REFERENCES [1] F. Akyildiz , Xudong Wang , Weilin Wang; Wireless mesh networks: a survey [2] Mihail L. Sichitiu ;Wireless Mesh Networks,Challenges and Opportunities

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[3] W. Steven Conner, Intel Corp,Jan Kruys, Cisco Systems,Kyeongsoo (Joseph) Kim, STMicroelectronics,Juan Carlos Zuniga, Overview of the Amendment for Wireless Local Area Mesh Networking [4] IEEE 802.11Standard Group Web Site. . [5] IEEE 802.15 Standard Group Web Site. . [6] IEEE 802.16 Standard Group Web Site. . [7] T.-S. Jou, D.E. Eastlake, ESS MESH Network Study Group Meeting Minutes, May 2004. [8] J. Jun, M.L. Sichitiu, The nominal capacity of wireless mesh networks, IEEE Wireless Communications [9] P. Piggin, B. Lewis, P. Whitehead mesh networks in fixed broadband wireless access: multipoint enhancements for the 802.16 standard, IEEE 802.16 presentation slides, Jul [10] P. Whitehead, P. Piggin, B. Lewis, S. Lynch Mesh extensions to IEEE 802.16 and 16a, IEEE 802.16 proposal, May 2003. [11] L. Krishnamurthy, S. Conner, M. Yarvis, J. Chhabra, C.Ellison, C. Brabenac, E. Tsui, Meeting the demands of the digital home with high-speed multi-hop wireless networks, Intel Technology Journal [12] S. Tierney, Mesh Networks, communitynetworking.org. [13] J. Jun, M.L. Sichitiu, The nominal capacity of wireless mesh networks, IEEE Wireless Communications [14] R. Poor, Wireless mesh networks, Sensors, February [15] R. Poor, Wireless mesh links everyday devices, Electronic Engineering Times, 5 July 2004. [16] I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cayirci, Wireless sensor networks: a survey, Computer Networks 38 (4) (2002) 393–422 [17] I.F. Akyildiz, J. McNair, H. Uzunalioglu, W.Wang, Mobility management in next generation wireless systems, [18] J. Walker, Wi-Fi mesh networks, the path to mobile adhoc. Available from:
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[19] Intel Inc., Multi-Hop Mesh Networks—a new kind of Wi-Fi network [20] H. Frey, Scalable geographic routing algorithms for wireless ad hoc networks, IEEE Network Magazine

WEBSITES [21] http//www.netstumbler.com [22] prtg network monitor [23] ubuntu [24] http//www.kismet.org [25] www.madwifi.org [26]www.wirelessmesh.wordpress.com www.mathworks.com www.airjaldi.com www.wikipedia.com www.google.com www.smartbridges.com www.linksys.com www.meshdynamics.com www.meshcom.con www.linux.com www.paessler.com http://wndw.net/pdf/wndw-ebook.pdf http://wire.less.dk/cantenna/ http://wirelessafrica.meraka.org.za http://download-master.berlin.freifunk.net http://www.dd-wrt.com/ http://www.chiark.greenend.org.uk/putty http://downloads.openwrt.org/whiterussian/ http://www.ietf.org/rfc.html

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Wi-fi MESH NETWORK : SURVEY OF EXISTING WIRELESS ...

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