Analytical description of the mean packet delivery time in a token ring based WLAN: the impact of the wireless channel

An analytical model to evaluate the mean packet delivery time in a WLAN implementing a token ring MAC protocol is presented and validated through simulation. Both the cases of an ideal and a faded channel are considered in the analysis: the model allows the introduction of the wireless channel characteristics, in terms of received power statistics of the first and second order. To this aim, a proper channel model is also presented that takes the typical characteristics of the wireless indoor channel into account. The analytical model gives a closed form derivation of the maximum offered load which keeps the system stable, and, thus, allows the assessment of the number of users to be admitted in the system. Through simulation the impact of the channel conditions on the maximum token holding time is also shown. It is found that, depending on the average signal-to-noise ratio experienced by the wireless terminals, the optimum maximum token holding time can be finite or not