Performance analysis of practical combinatorial mechanism with exponential backoff and retransmission cutoff

The paper investigates the combinatorial mechanism of a general case of exponential backoff (EB), with factor, r, and retransmission cutoff, with traffic sources consisting of an infinite number of stations in ideal channel conditions. A new, simple, but more exact, infinite-station bidimensional discrete-time analytical model based on a Markov chain, to reflect the actual behavior of this combinatorial mechanism, is presented. By means of the proposed model, we provide an extensive performance evaluation, and new analytical results are given. We also obtain the analytical expressions for the maximum saturation throughput, which converges to a non-zero constant as the station number goes to infinity. The accuracy of the analysis is verified by elaborate simulation results. In addition, the packet rejection rate is discussed for various values of system offered load and initial minimum contention window.