1983 Reports

A Family of Window Protocols for Time-Constrained Applications in CSMA Networks

Kurose, James F.; Schwartz, Mischa

In the design of random access CSMA protocols for time-constrained applications such as packetized voice, the distribution of message waiting times is of critical importance. It is shown that the ordering or scheduling imposed on message transmissions by a particular random access protocol greatly affects the message waiting time distribution. We present a random access protocol which can provide a large class of distributed message scheduling disciplines based on message arrival times. Moreover, this protocol can adaptively vary to provide an optimal service discipline in response to changing system demands. Analytic models are derived for the waiting time distribution for the cases of FCFS, LCFS and RANDOM scheduling and the analytic results are compared with simulation. Other possible scheduling disciplines are discussed and the impact of the distributed scheduling discipline on the performance of time-constrained applications is examined.