Performance analysis of inhibit sense multiple access with multiple idle signals

The inhibit sense multiple access (ISMA) system is known to obtain high throughput when a number of terminals transmit data packets to a base station over a common radio channel. However, the capture effect and propagation delay cause unfairness of local throughput depending on the distance from the base station. In this paper, we propose an ISMA which broadcasts N multiple idle signals with time difference to decrease the unfairness of local throughput without power control. In the proposed system, the area is divided into N regions in terms of the distance from the base station. The terminals in the farthest region use the first idle signal and terminals in the nearest region use the N-th idle signal to decrease the difference between the idle periods of the terminals. Local throughput and total through put are analyzed by numerical calculation and computer simulation. It is shown that the unfairness of local throughput due to distance decreases without decreasing total throughput.