An analysis of a new carrier sensing scheme for undirectional bus CSMA networks

A new carrier sensing scheme for CSMA protocol on unidirectional bus topologies is proposed and analyzed. Several existing networks such as cable TV data networks and the well known broadband Ethernet (IEEE 802.2 10BROAD36) have a unidirectional bus topology. The proposed scheme combines carrier sensing on the inbound and the outbound channels. Distances to the head end are specifically included in our model using space-time techniques. The analysis is carried out for the case of a nonpersistent CSMA protocol. Several load distributions are investigated numerically. A significant increase in throughput is observed, especially when the stations are clustered on the opposite side from the head end. The probability of success for a test packet conditioned on the distance from the head end is calculated. This probability is used to discuss the fairness of the proposed protocol