Performance analysis of a CDMA ALOHA network with channel-sensing

It has been shown by Lo, Ng and Yuk (see IEEE JSAC issue on CDMA Networks III, 1996) that the throughput-delay performance of a CDMA ALOHA network, where each station is assigned a spreading code so that each effectively has its own 'virtual channel', and where channel sensing and collision detection are also used, is much better than that of a simple CSMA-CD network. Such a system, however, is difficult to implement. A simpler system that may provide good performance and that is easy to implement is a CDMA ALOHA network with just channel sensing. The channel sensing can be provided by a simple correlator and threshold device. The performance of such a network is investigated, and some comparisons are made with those of the simple CSMA-CD network and the CDMA ALOHA network with both channel sensing and collision detection. It is shown that when the CDMA-CS network is stable, its performance is not much worse than that of a CDMA-CS/CD network, and much better than that of a simple single channel CSMA-CD system.