Enhanced Two-Level Frame Aggregation with Optimized Aggregation Level for IEEE 802.11n WLANs

IEEE 802.11n defines a significant two-level frame aggregation scheme aimed at improving the transmission efficiency of MAC layer. However, the performance of the two-level frame aggregation scheme does not meet the user expectation due to the inevitable aggregation and retransmission overheads. To overcome this problem, an enhanced two-level frame aggregation with the optimized aggregation level is proposed in this letter for IEEE 802.11n wireless local area networks (WLANs). In the proposed scheme, in order to maximize the throughput of the two-level frame aggregation, the aggregation level (i.e., sub-MPDUs, the number of the aggregated sub-MAC protocol data units) used for the two-level frame aggregation is optimized and adjusted dynamically according to the subframe size, the maximum aggregation level (MAL) allowed by the current two-level frame aggregation and the real-time channel bit-error-rate (BER). Results from the simulation show the superiority of the proposed enhanced two-level aggregation in respect of throughput performance.