Analysis and Comparison of Burst Transmission Schemes in Unsaturated 802.11e WLANs

Contention free bursting (CFB) and block acknowledgement (BACK) are two efficient burst transmission schemes specified in the IEEE 802.11e standard for improving the utilization of scarce wireless bandwidth. Most existing performance models of the CFB and BACK schemes have focused on the analysis of system throughput and have not taken the realistic factors, such as unsaturated traffic loads and finite buffer capacity, into account. In this paper, we propose a comprehensive analytical model for evaluating the throughput, end-to-end delay, and loss probability of burst transmission schemes in wireless local area networks (WLANs) under unsaturated traffic conditions. The accuracy of the proposed model is validated through extensive ns2 simulation experiments. Performance results obtained from the model demonstrate that both schemes can substantially improve network performance. Moreover, the BACK scheme outperforms the CFB scheme when the transmission opportunity (TXOP) limit exceeds a certain threshold.