Revisiting the IEEE 802.11n A-MPDU Retransmission Scheme

The aggregate MAC protocol data unit (A-MPDU) and Block Acknowledgment (Block Ack) techniques are among the pivotal MAC layer enhancements introduced by the IEEE 802.11n amendment. Although they have been studied extensively in the literature, recent research studies have proven that the existing analytical models proposed for those techniques are not conform to 802.11n standard specifications, since they do not capture the effect of the Block Ack window limit on the aggregation size which provokes critical errors in the estimation of 802.11n MAC layer performance. In this letter, we elaborate a new analytical model compliant with the conventional A-MPDU retransmission scheme to conduct an accurate analysis of the performance of A-MPDU and Block Ack techniques under different network conditions. To validate the accuracy of our model, we compared the numerical results to those obtained using ns-3 simulator and with two other analytical models investigating the performance of 802.11n MAC layer.