Unslotted Hybrid CDMA/ISMA Protocol for Indoor Wireless Computer Communications

More Info


A hybrid Code Division Multiple Access / Inhibit Sense Multiple Access (CDMA/ISMA) protocol has been proposed as an effective multiple access scheme for Indoor Wireless Computer Communications. This new protocol combines the advantages of both CDMA and ISMA into one protocol. On the one hand the ISMA protocol introduces a limitation to the number of simultaneous accesses to the transmission channel. On the other hand the CDMA protocol introduces an improvement to the packet survival chance. It is shown that the performance of the hybrid protocol is indeed better than CDMA only. In addition, code sharing can be applied to reduce hardware cost. The slotted hybrid CDMA/ISMA protocol using the p-persistent ISMA scheme has already been analysed. In this report, we investigate the hybrid protocol using the unslotted non-persistent ISMA scheme. The analysis is done for a star-connected multiple access wireless computer network. The performance comparison between the slotted and unslotted hybrid CDMA/ISMA protocol is evaluated in terms of throughput and delay using computer simulation and mathematical analysis.