On the Stability and Optimal Decentralized Throughput of CSMA with Multipacket Reception Capability∗

With the improvement of the physical layer’s ability to receive multiple packets sent simultaneously, the classical collision channel model no longer applies and a general MPR model should be employed. We investigate the effect of MPR on the CSMA protocol, which previously have not been studied under such model. By analyzing the stability region of CSMA, we find that CSMA’s open-loop throughput is the same as that of S-ALOHA when signal propagation delay is considered. Then we derive the optimal decentralized closed-loop throughput of CSMA and conclude that carrier sensing can provide throughput gain over S-ALOHA but only if the MPR capability is not sufficiently strong. Essentially carrier sensing can be interpreted as an enhancement over optimal scheduling, both of which become unnecessary for strong physical layers.