Performance of a coded band-limited spread-spectrum multiple-access scheme using channel sensing

The authors introduce and study the message delay and channel throughput behavior of a channel-sense multiple access/spread-spectrum (CSMA/SS) scheme. It is assumed that each net station can gain information as to whether the total number of ongoing transmissions exceeds a given threshold, M, or not. This entails, for example, the availability of an ancillary low-rate out-of-band or in-band signaling channel. A transmitting station will abort its transmission upon the reception of a signaling message indicating that the current number of transmissions exceeds the prescribed threshold. A random-access scheme is used to control the access of messages to the channel. Using derived performance equations, numerical results are presented illustrating the delay-throughout performance of such a CSMA/SS scheme. Key parameters involved in this performance analysis include: channel bandwidth, error-correction code capability, and propagation delay. Given an average message length, an activity threshold level M can be selected to yield the best delay-throughput performance characteristics