Approximate Output Processes in Hidden-User Packet Radio Systems

The processes consisting of the packet interdeparture times for contention-type packet broadcasting systems in a hidden-user, singlehop environment are studied under the heavy-traffic assumption. The channel access protocols considered include pure ALOHA and unslotted nonpersistent carrier-sense-multiple-access (CSMA). The theory of superposition of independent renewal processes is applied to approximate the distribution of the duration of each unsuccessful transmission period in channel state. Our analysis results for the channel throughput and the coefficient of variation for the packet interdeparture time in symmetric configurations are shown to be in good agreement with simulation results over a wide range of offered channel traffic.