Performance Optimization of a CSMA Protocol for Local Computer Networks

Notable among local computer network protocols is the carrier sense multiple access (CSMA) network protocol. Many versions of CSMA have been proposed. The purpose of this paper is to derive an optimized performance of one version of CSMA, slotted nonpersistent CSMA with truncation (CSMA-SNP/TR), which is known to have better throughput performance than all other versions of CSMA. In this paper, the optimum average retransmission delay which provides the maximum throughput is presented in terms of message propagation delay, average retransmission delay, and number of terminals. Since the optimum average retransmission delay varies depending upon the number of terminals, an optimal average retransmission delay which nearly maximizes the throughput for a range of terminals is derived. A queueing model for representing the CSMA-SNP/TR protocol to analyze the performance of a computer network is also established. This work can be useful for design and performance analysis of distributed computer systems, including the computer systems and the communication channel connecting the computer systems.