Unslotted 1- and p/sub i/-persistent CSMA-CD protocols for fiber optic bus networks

Abstract

Analyzes the performance of the unslotted 1-persistent carrier sense multiple access with collision detection (CSMA-CD) protocol for fiber optic bus networks with a finite number of stations M, each of which has an infinite storage buffer for storing packets with its length fixed or exponentially distributed. Treating the bus network as an M-class priority queueing system with a preemptive repeat-identical retransmission strategy, the authors show numerically that this 1-persistent retransmission strategy provides better delay-throughput performance than the non-persistent one. To satisfy the fairness of equal delays among stations in the bus network, the authors next present the unslotted p/sub i/-persistent CSMA-CD protocol. Under this protocol, the first packet arriving at station i is forced to enter into the backoff procedure with the probability of (1/spl minus/p/sub i/). After backoffs, transmission begins until the station becomes empty. The authors determine the persistent probability p/sub i/ and show that the delay-throughput performance of the p/sub i/-persistent strategy is better than that of the 1-persistent one, and further it is robust for any packet lengths. Simulation results are presented to verify the analytical results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>