An adaptive retry scheme for delay-constrained service transmission in 802.11n system

Owing to the high data rate of IEEE 802.11n, high-definition video transmission becomes one of its major applications. However, it´s still difficult for contention-based MAC layer to provide enough QoS guarantee for such latency-sensitive applications. This paper has analyzed the performance on delay, throughput and packet loss rate in error-prone channels based on the frame aggregation mechanism of 802.11n MAC layer, and a scheme to dynamically adjust the retry limit to meet the delay constraint is proposed. More specifically, retransmission is distinguished to two types, i.e. collision retransmission caused by collision with other wireless nodes, and error retransmission caused by bit corruption. A new error retry counter is introduced to describe the times that a frame is retransmitted due to bit corruption. Then, the paper proposes an adaptive scheme to constrain the delay by adjusting the times of retransmission due to collision and error respectively, and simulation results show its good performance on delay control.