PERFORMANCE OF RESERVATION PROTOCOLS IN A MOBILE WIRELESS LOCAL AREA NETWORK

Abstract

An architecture based on packet transmission has been proposed by Goodman et. al. [5] to meet the characteristics of third-generation wireless systems. It consists of a wireless network infrastructure, referred to as a cellular packet switch, and a terminal-to-base transmission protocol, referred to as packet reservation multiple access (PRMA) [5,9]. In this thesis, we focus our investigations on the performance of this PRMA protocol in realistic mobile radio channels. A simulation model for PRMA in error-free channels is first described and its accuracy is validated by comparing some results obtained with those published in [11]. The model is then varied to study the performance of PRMA in erroneous channels. A channel propagation model which considers the effects of various channel propagation impairments, such as multipath fading, shadowing and distance-dependent path loss, is also devised. Results show the performance of PRMA degrades significantly in the presence of channel defects. Specifically, a reduction in capacity of up to 27% is observed in certain cases. These degradations in performance are attributed to channel errors causing the premature loss of reservations and increased collisions. To reduce these performance degradations, the modified-PRMA (MPRMA) [32,33,34] protocol has been proposed. Its performance in erroneous channels is also analyzed mathematically and validated using simulation. The MPRMA protocol is shown to be less susceptible to channel errors than PRMA. In particular, improvement of up to 15% over the performance of PRMA is observed.