QUEUING ANALYSIS OF CDMA UNSLOTTED ALOHA SYSTEMS WITH FINITE BUFFERS

CDMA unslotted ALOHA system with finite size of queueing buffers is di scussed in this paper. We introduce an analytical model in which the s ystem is divided into two Markov chains; one is in the user part, and the other is in the channel part. In the user part, we can model the q ueueing behavior of the user station as an M/G/1/B queue. In the chann el part, we can consider the number of simultaneously transmitted pack ets as an M-1 + M-2/D/infinity//K queue. We analyze the queueing syste m by using this analytical model, and evaluate the effect of buffer ca pacity in terms of the throughput, the rejection probability and the a verage delay. As a result, increase in the buffer size brings about an improvement in the grade of service in terms of higher throughput and lower rejection probability.