Suppressing Selfish Transmissions with Extending NAV Period and Resetting CW of Access Point in Wireless LAN

摘要

In case that a selfish terminal generates a large amount of traffic with high priority control of IEEE 802.11e, an access point (AP) and terminals in the AP cannot get transmission opportunities because of the media access control technique. In our previous work, we proposed traffic suppression method for the selfish terminal by cooperative controls between AP and terminals with considering the fairness of upstream traffic and down stream traffic. In the method, a Fake period is added to the Network Allocation Vector (NAV) and a dynamic contention window (CW) control of AP suppress excessive transmission of the selfish terminal at the initiative of AP. However, the previous method cannot completely suppress traffic of the selfish terminal because the current backoff of AP cannot be adjusted until next its transmission success. In this paper, AP retrieves its transmission opportunities from the selfish terminal with resetting its current backoff when AP receives a frame from the selfish terminal. In addition, the transmission opportunity of downlink communication is ensured with an improved control of the fake period. Effectiveness of the proposed method is evaluated in computer simulation.