Throughput performance of an unslotted direct-sequence SSMA packet radio network

A spread-spectrum multiple-access (SSMA) packet radio network model is presented. The topology is a fully connected network with identical message generation processes at all radios. Packet lengths are exponentially distributed, and packets are generated from a Poisson process, resulting in a Markovian model. This network model accounts for the availability of idle receivers in a finite population network. The model also allows the performance of the radio channel to be specified in detail. The channel considered is a BPSK (binary phase-shift keying) direct-sequence SSMA radio channel with hard-decision Viterbi decoding. An analysis of the Viterbi decoder leads to a bound on its performance which is valid for a system with a varying probability of error, as is the case for the network under consideration. The approximate analysis yields lower bounds on throughput and probability of successful packet transmission. Results are given which show the effects on throughput of the received energy-to-noise density ratio, the number of chips per symbol, and the number of radios, as well as the improvement due to error control coding