A discrete-time approach to the modeling of carrier-sense multiple-access on the bus topology

An exact analysis of the carrier-sense multiple-access (CSMA) protocol on the bus topology is presented. All stations are synchronized to twice the distance between the uniformly distributed stations. The packet transmission time is an integer multiple of this synchronization step, and is at least equal to twice the end-to-end propagation delay. The makes the operation semisynchronous, rather than synchronous or asynchronous. The model is formulated as a time-homogeneous embedded Markovian chain and is solved under the steady-state condition. Both heterogeneous and homogeneous systems are considered. The system throughput is evaluated as well as the individual station throughput. The theory that the throughput achievable on the bus topology is greater than that achieved on a synchronous system is confirmed. It is also shown that the individual station throughput depends on the station location on the bus, and that stations near the center of the bus achieve higher throughput values