Analysis of carrier sense multiple access with priority acknowledgements (CSMA/PA) on noisy two-way channels with finite user population

Carrier sense multiple access (CSMA) is discussed as an efficient and simple means for decentralized access control to a common communication channel shared by several users. The delay and throughput performance of CSMA with priority acknowledgments (CSMA/PA), a scheme which enables message and acknowledgment packets to share the same communication channel bandwidth effectively, are calculated. The analysis includes the effect of channel errors on both message and acknowledgment packets, user population size and modem detection, and synchronization delay. Excellent agreement is observed between the analytical results and those obtained from measurements on an actual noisy five-node intrabuilding power line LAN operating at transmission rates ranging from 1.2 to 9.6 kb/s.<>