Analysis of a multiple access radio communication system for monitoring vehicles carrying hazardous loads

The paper considers a multiple access, satellite-based system used to collect position reports from vehicles distributed across a wide geographical area. The power with which a vehicle´s transmission is received depends upon its location. The paper considers the case of two groups of users, each associated with a particular received power, and develops a Markov chain model for the number of backlogged users in each group. The steady state behaviour of the chain is investigated in the presence of a finite power capture effect and the mean utilisation versus access delay characteristics obtained. It is shown that the possible utilisation is not fairly distributed between the two groups. Optimal retransmission strategies are proposed to investigate this effect