CAPTURE AND RETRANSMISSION CONTROL IN MOBILE RADIO

In this paper, we consider the slotted ALOHA protocol with capture, in a mobile communication environment, in the presence of Rayleigh fadin g and log-normal shadowing. The capture probabilities and their asympt otic value, as the number of colliding packets tends to infinity, are computed. A sufficient condition, under which this limit is positive, is identified and expressed in terms of the spatial distribution of th e users. Also, various models for this latter distribution are discuss ed. These results help identify the region in which the system may ach ieve a positive stable throughput. Finally, a retransmission control s cheme, that enhances the throughput, is considered, and the stability of the system is rigorously proven. We also show that the use of retra nsmission control is unavoidable if the network performance predicted in some recent literature is to be achieved.