Modelling of methods for wireless network access

by Barry, Thomas Andrew

Modelling of Methods for Wireless Network Access Thomas Andrew Linden Barry The upsurge in the use of video-capable, high powered mobile cornputers,driven in part by access to the Internet, have customers demanding remote access to high speed networks capable of providing access to a wide range of multimedia services. These services include video on-demand, live television nom many sources, fûllmotion video, multimedia electronic mail and CD-quaiity music and are referred to as broadband services because of the high bandwidth (100s of Mbps) needed to deliver them. As a consequence, there is now much interest in the topic of wireless access methods to these broadband wire networks. In a wireless environment, the transmission medium is regulated and expensive to set up. Ttierefore, the efficient utilkation of the available bandwidth is one of the important factors to be considered in the design of access methods. In a video-conferencing environment, the participants (using video tenninals) are more concerneci with the variations in the delay (playout jitter) than with the actual delay of the video stream. This need arises f?om the requirement that the video stream be srnooth and continuous when it is played out at the receiver. Correction for jittzr has implications for the mernory requirements of the video tenninals. In this thesis, we evaluate the performance of six approaches to wireless network access in a video-conferencing environment. The six approaches are examined in two scenarios, each with different video rates as well as for different data rates and for different lengths of the transmission cycle. The key performance measures used are the delay and the delay vuriarion expenenced by the video traffic. Performance results are obtained for the approaches using simulation and a comparative analysis based on the performance measures is presented. Finally, memory requirements derived fiom the delay and delay variation of each of the approaches are discussed.