IEEE 802.11s implementation for multimedia campus networking Arunabh Mishra, D. Kandar and Rabindra Nath Bera Sikkim Manipal Institute Of Technology, Sikkim Manipal University, Rangpo, Sikkim -737132

Abstract: 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 testbeds that have been set up for testing the various parts of a wireless mesh network.

using one type of radios on devices. Moreover, the requirements on end-user devices is increased when compared to infrastructure meshing.

I. INTRODUCTION

W

ith 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 [4,7], IEEE 802.15[5,8]and 802.16 [6,9,10] The architecture of WMNs can be classified into three main groups based on the functionality of the nodes:[1,2] 1) Infrastructure/Backbone WMNs. This type of WMNs includes mesh routers forming an infrastructure for clients that connect to them. The WMN infrastructure/backbone can be built using radio and 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 and user communication, respectively.

Fig 2 : Client WMN

3) Hybrid WMNs. This architecture is the combination of infrastructure and client meshing as shown in Fig. 5. Mesh clients can access the network through mesh routers as well as directly meshing with other mesh clients. The infrastructure provides connectivity to other networks such as the Internet, Wi-Fi, WiMAX, cellular; the routing capabilities of clients provide improved connectivity and coverage inside the WMN.

Fig 3 A hybrid WMN showing mesh clients and mesh backbone

II. CHARACTERISTICS OF WMN Fig. 1 A Infrastructure/backbone WMN

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.Client WMNs are usually formed

The characteristics of WMNs are explained as follows: • Multi-hop wireless network. [11] • Support for ad hoc networking, and [12]. • Mobility dependence • Multiple types of network access [13] • Dependence of power-consumption constraints [14,15] [16,17]

• Compatibility and interoperability with existing wireless networks. [18,19,20] • Wireless infrastructure/backbone. • Dedicated routing and configuration • Multiple radios. • Mobility. III. APPLICATIONS OF WMN 1) Home networking The WMN can be successfully deployed to provide home user with the basic services such as networking, internet, VOIP and multimedia streaming and broadcasting. 2) Entreprise networking This refers to small network in an office or a medium size network comprising of all the offices in a building. Traditionally the isolated IEEE 802.11 networks are used, where intermediate connection is based on Ethernet wiring. Thus extending the network is high cost affair and adding more backhauls causes increased capacity. 3) Transportation systems The present network at stations and stands is based on 802.11 and 802.16 protocols. By using the 802.11s the network can be extended to buses, trains and ferries. Even the DSSS spectrum based 802.11p VANET can be employed using wireless mesh networks. 4) Health and medical systems The health centres and hospitals frequently require the exchange of information between individual department. By extending this network using mesh more devices can be added to the network. 5) 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. 6) Building automation In a building, various electrical devices including power, light, elevator, air conditioner, etc., can be controlled and monitored using WMN.

Fig 4

Graph showing kbps vs time for different protocols.

The work was also extended to a linux based platform working on Linux distro Ubuntu[23]. Under linux development the wireless readings were taken using Kismet[24] – an 802.11 based wireless network detector and sniffer. MadWiFi[25], the open source advanced WLAN driver was employed. A wireless ad hoc network was installed inside the lab and was tested for data rates and signal strength under the linux platform.

IV. SOFTWARE DEVELOPMENT The software development platform for multimedia campus networking is based on windows platform. An initial survey of the SMIT campus was done for wireless access with already existing AP. The results were taken using netstumbler[21]- a tool for windows that facilitates Wireless LANs using 802.11 a/b/g standards and linksys software. The traffic monitoring system was also tested for wired LAN system existing in campus using PRTG network monitor software[22]. It was used to map traffic, using packet sniffing protocol, which will be employed in future to monitor wireless traffic

Fig. 5

Graph of SNR versus time, using Netstumbler

Fig 6 : A chart showing bandwidth(kbps) vs time for different protocols using PRTG network monitor.

V. MESH IMPLEMENTATION MODEL

RF bandwidth = 20 MHz

The authors are trying to extend the work to MATLAB[26], and are working on a simulation model of the 802.11s layered architecture. They are also working on multimedia transmission through wireless channel. 1. A study was also made on different factors affecting a wireless transmission rate for a mesh network. Marginal S/N 2. Long bursts of interference due devices working in same spectrum. eg microwave 3. Short bursts of interference due to concurrent sends from other routers 4. Multipath interference. The efficiency of deployed network depends on following performance metrics. 1. SNR 2. Noise 3. Bandwidth 4. User Traffic We intend to deploy a ESS( Extended Service Set), which consists of four cells and a wireless backbone consisting of 2.4 GHz based on wi-fi. The cell consists of a set of access points and user terminals which may be a laptop, desktop, PDA etc. The two basic modes of deployment will be (1) Point to point (2) Point to multipoint. 1) Point to Point Deployment The point-to-point deployment of wireless mesh has been successfully implemented. The setup used was that of DSSS radar system. The deployment was done using 802.11n/g backbone. The transmitter and receiver were two parabolic reflectors and the setup was tested for the range around 110 meters. 1(a) The DSSS System: A DSSS communication system made up of WiFi b PCI adapter (Shown in Fig. 7) fitted inside a PC acting as Transmitter and another DSSS communication system made up of another WiFi b PCI adapter fitted inside another PC acting as Receiver are operational at SMIT using 2.4 GHz radio carrier. The transmitter and Receiver are separated at a distance of 110 m. The Block diagram and photograph of such communication system are shown in Fig 3 and Fig. 4 respectively. The transmitter radiates carrier using a dish antenna of diameter 6 ft with a horn at its focus. The horn is connected to WiFi b adapter fitted inside a PC. At the other end the receiver with another WiFi b adapter and a second horn is placed. The received signal spectrum is as shown in Fig.7 below having the following system parameters.

S/w MATLAB 7.4

WiFi b Card

WiFi b Card

Fig. 8. Photograph of the operational DSSS System at SMIT.

The readings were taken for SNR, noise level and signal strength over the experimental setup.

Fig. 9 The received signal Spectrum from a DSSS System

2) Point to Multipoint Deployment The point to multipoint deployment is being work upon and we intend to use wireless backbone consisting of wireless routers using mesh network.The wireless mesh network was established using WRT54G routers and WRTusbG adapter. The readings were taken in linux terminal which gave the frequency, channel and mode along with signal strength. A cell is configured using linksys routers and two cells are networked with one another using other sets of router. The cell 1 and cell 2 are connected using a wireless backbone of mesh network. Thus the mesh points are configured for better QoS and new MP can be added easily due to dynamic nature inherent to 802.11s architecture.

S/w in Matlab 7.4 Fig 10 A point to multipoint mesh deployment using routers and switches

Fig. 7 Block Diagram of the Operational DSSS System at SMIT

RF carrier Frequency = 2.4 GHz Rate = 11 Mbps

VI. MULTIMEDIA APPLICATION The audio/video multimedia application was tested in HALO ( Hardware in the loop) environment using IEEE

802.11n network adapters using UDP(User Datagram Protocol). The forward path was implemented using Microsoft netmeeting and a pulse was transmitted using wi fi 802.11n adapters. The reverse path/loop back path was implemented using the vlc player where by the received pulse was re transmitted 2) Experimental Specifications: 1. Forward Path: Microsoft net meeting was used for the forward path. 2. Reverse path/ loop back: VLC player for the loop back.(UDP protocol/RTP protocol).The pulse was transmitted in mp4v video format, using video streaming. 1) Basic block diagram

Fig 13: The receiver output as seen at receiving PC monitor.

5)

Transmitted

and

output

pulse:

Fig 14: The transmitted pulse. Output pulse and sync pulse observed in digital storage oscilloscope.

Fig 11: The basic block diagram for multimedia application testing using hardware in the loop.

3) Transmitter output

VII. CONCLUSION The capability of self organisation in WMN reduces network complexity. The wireless backbone of router provides a viable solution over other existing network protocols. The deployment of wireless mesh over a region must be tested to provide user end with a better QoS and sufficient bandwidth. The present 802.11s system is being tested for various multimedia application and bandwidth. The work has been extended to MATLAB 7.5. VIII. ACKNOWLEDGMENT The authors would like to thanks Dr. R.N. Bera for his invaluable assistance at BBCN( Broadband Communication Network) lab at Sikkim Manipal Institute of technology. Also the co students working on relevant project provided support for the above literature.

Fig 12 The transmitted pulse from pulse generator transmitted using netmeeting

Encapsulation Method Transcoding Method Video/audio codec Bitrate 4) Receiver Output:

MPEG TS UDP/RTP method MP4V/MPGA 192 Kb/s

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