A modified CSMA-CD protocol for high speed channels

Abstract

A modified carrier-sense multiple-access with collision detection (CSMA-CD) protocol which is suitable for high-speed channels is presented and analyzed using the equilibrium point analysis (EPA) method. With the protocol each user has a finite buffer and does not transmit until it has accumulated a given number of packets, L. When this number is exceeded it will access the channel using a conventional CSMA-CD protocol and transmit all the packets in its buffer. This protocol is very simple to implement compared with multichannel protocols and results in higher throughput compared with slotted Aloha. The disadvantage is a larger delay, which is related to the parameter L, the packet arrival process, and the number of users. The delay can be reduced by dynamically controlling the parameter L and the retransmission probabilities of the protocol. The protocol is well suited for traffic arrival processes which are bursty where each burst of packets corresponds roughly to a message. Some performance results are given assuming a Bernoulli packet arrival process.