Throughput and Delay Performance of IEEE 802.11e Wireless LAN with Block Acknowledgments

The IEEE 802.11e standard extension for medium access control protocol in wireless local area networks enhances the existing IEEE 802.11 protocol specification towards support for quality of service and improved spectrum management. We look in this paper specifically into an 802.11e concept that is referred to as block acknowledgment. Unlike the original 802.11, where every frame reception must be acknowledged independently, block acknowledgments offer the possibility to acknowledge several consecutive data frames in one response. This obviously may help to decrease the protocol overhead, but is expected to introduce higher end-to end delays for the data frame transmissions. We present a closed-form analytical analysis of the block acknowledgment protocol, and compare our findings to simulation results. Our results show that whereas throughputs improve considerably when block acknowledgments are applied, care has to be taken not to increase the delays above unacceptable durations.