Performance analysis of CSMA/CD‐DRC system

Abstract

Multimedia communication systems must handle two types of messages, one is data type and the other is voice type. Data type messages can tolerate longer delay but voice type ones cannot. Though communication systems with huge capacity by optical fibers and ATM switches have little problem for multimedia communication, most of the present LANs cannot handle messages, especially voice type ones, satisfactorily because of their poor capacity. In this paper we propose a new protocol for LANs, CSMA/CD‐DRC (Carrier Sense Multiple Access with Collision Detection and Dynamic Retransmission Control). This protocol is for the multimedia communication systems which must handle those two types of messages but do not have enough channel capacity, and controls retransmission rates dynamically to achieve higher throughput and shorter delay for voice type message. Moreover, we analyze the protocol in order to confirm its performance. In analysis we derive Laplace–Stieltjes transform (LST) of the probability distribution function (PDF) of the performance measures. Through LSTs, we can calculate not only averages but also higher moments of performance measures as well as coefficients of variation. We also present some numerical results, from which we find the proposed protocol can improve the system performance.