IMPROVING THE PERFORMANCE OF INTEGRATED SERVICE NETWORKS USING SELF ADAPTIVE CSMA/CD AND VARIOUS CONTROL ALGORITHMS

In this paper, a study of mixed voice and data on a local area network using Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is presented. In multi-access/broadcast systems, each station is connected to a common communication medium (such as a bus) through an interface to listen to all transmissions and copy packets that are addressed to it. Since no more than one transmission can be carried on the bus at a time, the stations have to share the bus by means of a multiple access protocol. A variation on the carrier sense multiple accesses with collision detection (CSMA/CD) protocol for local area random access broadcast network was presented for supporting the facility of mixing both voice and data traffic over the bus LAN. This protocol transmits into an idle channel with a dynamic probability (P) and back of with probability (1-P). To handle the collision state, we examine various retransmission policies. Simulation results are presented to illustrate the effectiveness of the various retransmission approaches in comparison with the traditional CSMA/CD that uses binary backoff algorithm to handle the retransmitted packets in case of existing a collision in the channel. It is concluded that by suitable choice of the control parameter and the appropriate retransmission policy, optimum throughput can be achieved and the voice packet loss due excessive delay may be kept below the threshold of 0.52 percent.