Throughput analysis of asynchronous CSMA protocols on star-like LAN topologies

Abstract

An analysis of asynchronous (unslotted) carrier sense multiple access (CSMA) protocols applied to starlike topologies of local area networks is presented. Networks with a starlike topology include wireless LANs, STARLAN, the unidirectional bus and fiber-optic star topologies. The widely used assumption in starlike networks that the stations are at a constant distance from the repeater is eliminated. In the analysis, the authors explicitly model the spatial distribution of offered traffic through the use of a load intensity function. Results for the case of a uniform load intensity function show the throughput to be significantly larger than in the case of a topology with equidistant stations. It is also shown that at higher loads, for some cases of the load intensity function, the asynchronous protocol has a higher throughput than slotted (synchronous) CSMA.