Extending Throughput Performance for Low SNR Scenarios in WLANs Using Two-Level Frames Aggregation with Enhanced A-MSDU

IEEE 802.11n standard is deployed virtually everywhere: on residences, offices, university campuses, and even market places. However, throughput obtained by end users have not measured up to the speed range of between 100 and 600 Mbps stipulated in the standard due to the Physical (PHY) technology involved and timing headers at the Media access control (MAC). To overcome this, two frames aggregation schemes, namely, A-MSDU and A-MPDU were introduced as a means of utilizing channel efficiency at the MAC through amortization of the overheads over multiple frames. However, there are still issues with additional headers from aggregating frames. We know that A-MSDU performs well in clear channels and small aggregation sizes but poorly with increasing channel error and larger aggregation sizes, while the opposite is true for A-MPDU. Thus, several authors exploited their complimentary efficiencies to derive two-level aggregation schemes, resulting in higher throughput, headers reduction, and channel utilization. However, these gains are totally eroded at SNR of 19 dB and below. Using NS3 discrete event simulator, we therefore propose a two-level frame aggregation scheme that utilizes the enhanced A-MSDU and A-MPDU, using appropriate algorithm depending on the SNR value. Our work increased the SNR range for throughput performance by 37.5%; increased channel utilization by 40%, 36%, and 31% at SNR variants of 19 dB, 17 dB, and 16 dB respectively.