Improving efficiency and fairness in IEEE 802.11 infrastructure WLANs with station-to-station traffic

In a wireless local area network (WLAN) configured with the infrastructure mode, the access point (AP) not only handles the download or upload traffic between the Internet wired hosts and the mobile stations, but also forwards the traffic from a mobile station to a mobile station, which is called the station-to-station (S2S) traffic. In the IEEE 802.11 distributed coordination function (DCF), all the mobile nodes and the AP have the same probability to access the medium. Therefore, the total probability of uploading packets from all mobile stations is much more than the probability of transmitting packets from the AP. Consequently, the AP becomes a bottleneck and results in the unfair bandwidth sharing problem, which has received considerable attention recently. However, most of the existing works on this problem did not take the station-to-station traffic into consideration. In this study, a mechanism with dual queues and multiple transmission opportunities is proposed to tackle this problem. The proposed mechanism can be implemented at the AP in the MAC layer without modification of the standard wireless communication protocol for the mobile stations. Simulation results show that, in an infrastructure WLAN, the proposed mechanism not only can improve the efficiency and fairness but also can enhance the throughputs of station-to-station traffic.