PERFORMANCE OF A WIRELESS ACCESS PROTOCOL ON CORRELATED RAYLEIGH-FADING CHANNELS WITH CAPTURE

The throughput performance of a wireless media access protocol taking into account the effect of correlated channel fading, capture, and pro pagation delay is analyzed. For efficient access on the uplink (mobile -to-base-station link), the protocol makes use of the uplink channel s tatus information which is conveyed to the mobiles through a busy/idle flag broadcast on the downlink (base-station-to-mobile link). A first -order Markov model is used to describe the correlation in the packet success/failure process on a Rayleigh-fading channel. The analytical r esults obtained through the first-order Markov approximation of the ch annel are compared to those obtained from an independent and identical ly distributed (i.i.d.) channel model. The Markovian-fading channel mo del is shown to provide better performance results than the i.i.d. cha nnel model. Simulations show that a first-order Markov approximation o f the Rayleigh-fading process is quite accurate. An enhanced version o f the access protocol to take advantage of the memory in the fading ch annel behavior is proposed and analyzed. The effect of retransmission of erroneous data packets and propagation delay on the throughput is a lso analyzed. It is shown that the access protocol with an error detec t (ED) feature is efficient in slow fading (e.g., pedestrian user spee ds), whereas a retransmission protocol is more efficient in fast fadin g (e.g., vehicular user speeds).