Buffer analysis in random multiple access broadcast communication systems

In much of the literature related to the queueing analysis of random multiple access schemes, the analysis has been made assuming user buffer lengths of either one unit or infinity. However, the buffer lengths used in practice are finite and, in general, larger than one unit. The authors describe an approximate queueing model to evaluate system performance for finite buffer lengths larger than one unit. The system state is represented by a two-dimensional vector v=(n,k), where n and k are the number of busy terminals and the total number of outstanding packets in the system, respectively. A numerical procedure is described to calculate the expected delay, expected throughout, expected buffer occupancy and the probability of buffer overflow. Numerical results showing the effect of buffer length variations on the system performance are presented for the Optimal Aloha and the Urn schemes.