WLAN 802.11 MAC anomaly mitigation using SNR to control backoff contention window

WLAN using the standard 802.11 presents a MAC anomaly when in the same access point operates stations with different data rate. The MAC anomaly is first obtained analytically to show the throughput degradation. The analyze result shows that the degradation is higher for the station with high data rate that operates with good signal to noise ratio. The station with low SNR has higher throughput. To evaluate the anomaly an experimental test was created to obtain the WLAN behavior with wireless host transmitting with low SNR together with hosts with high SNR. The anomaly was evaluated experimentally utilizing two architectures: fat and thin. The anomaly was detected in the fat architecture and was not detected in the thin architecture. The evaluation uses downlink UDP traffic, which is responsible for the main parts of WLAN network traffic. This paper presents a strategy to justify the result obtained with thin architecture, using SNR to control contention window to mitigate the anomaly. The strategy configures the wireless stations with low SNR to work with large contention window and wireless stations with high SNR with small contention window. With this strategy the station with high SNR obtains higher throughput than the station with low SNR