Performance analysis of inhibit sense multiple access with mixed priority classes

A random access system is considered promising in wireless communication where multiple terminals send packets to a single base station, using a single channel. Among these systems, the inhibit sense multiple access (ISMA) system is known as a system that can realize a high throughput. It is also desirable in wireless communication to provide a priority function to handle various kinds of traffic with different quality requirements, in order to cope with future multimedia systems. A problem within the conventional ISMA system, however, is that all packets are handled on an equal basis; traffic with priority is not considered. This paper proposes an ISMA system, where the base station sends multiple idle signals with a time difference, so that traffic with priority can be handled. The throughput and the delay performances are evaluated. It is shown that priority can be adjusted by adjusting the time difference of idle signals.