Performance Analysis of Block-ACK Scheme over IEEE 802.11n WLAN

Abstract

As the most widely used standard of WLAN, IEEE 802.11n leverages data rates at the physical layer and attempts larger throughput at the MAC (Medium Access Control) layer. Block-ACK scheme is one of most notable mechanisms to reduce the overhead of ACK frames and improve channel utilization. However, the common rate adaptation used is still based on the traditional Imm-ACK (immediate ACK).In this paper, we firstly investigate the problems of applying Block-ACK scheme to the classical rate adaptation and showed poor performance of these adaptations. Then we propose the enhancement mechanism for rate adaptation with Block-ACK over 802.11n system which selectively adopts the RTS/CTS mechanism. During the process, we analyze the impacts of some different important system parameters such as the number of stations. The simulation results show that the throughput can be improved with the enhanced mechanism.