Performance evaluation of a channel adaptive WLAN polling protocol

In this paper a wireless local area network (WLAN) with a polling MAC protocol is investigated. This work is the prosecution of an investigation activity on the performance of polling MAC protocols in fading channels, whose preliminary results were presented in Pasolini et al. (2001), and mainly deals with two aspects that Pasolini left open: the performance evaluation with bursty source traffic and the proposal of a channel adaptive MAC protocol solution. As far as the first aspect is concerned, in order to evaluate the impact on the protocol performance (which is measured in terms of mean packet delivery delay against offered traffic) of the source traffic characteristics, we consider both a Poissonian and a bursty traffic distribution. Concerned the second aspect, we introduce the concept of adaptively varying the maximum token holding time (MTHT) as a function of channel fluctuations: the results show that adopting this technique some performance improvements can be found with respect to the case of fixed MTHT.