Adaptively scaled back-off (ASB) mechanism for enhanced performance of CSMA/CA in IEEE 802.11ax high efficiency WLAN

This paper proposes an adaptively scaled back-off (ASB) mechanism to mitigate the performance degradations in the Binary Exponential Back-off (BEB) of IEEE 802.11 CSMA/CA in the highly dense environment such as IEEE 802.11ax high efficiency WLAN (HEW). The proposed ASB mechanism selects the optimal CW size to achieve maximized network performance adaptively based on the measured conditional collision probability (pc) and the estimated number of contending stations. The ASB protocol can provide higher efficiency than the legacy Binary Exponential Back-off (BEB) that simply adjust the back-off contention window (CW) size by blind exponential increase at repeated collision avoidance and resetting to the minimum value (CWmin) at successful transmission. The performance analysis of the proposed ASB scheme with ns-3 network simulation shows that the proposed ASB scheme can achieve 21.14% higher throughput and take 32.45% less average interval between successful transmissions than the BEB mechanism in highly dense WLANs with saturated traffic environment.1