Detection of malicious parameter configurations in 802.11e EDCA

The service quality experienced by a user with the EDCA mechanism of the upcoming 802.11e standard depends on a number of configurable parameters, namely CW_min, CW_max, AIFS and TXOP_limit. WLAN stations are supposed to use the parameter configurations that the access point (AP) of the WLAN distributes with the beacon frames. However, a user can maliciously configure the parameters of his WLAN station in order to obtain a better service. In this paper, we address the issue of detecting malicious parameter configurations of EDCA. The AIFS and TXOP_limit parameters are relatively easy to control because of their deterministic nature. Given the capture effect, the CW_max parameter may be unused by some users. Therefore, the key challenge lies in detecting if the CW_min parameter of a station is well configured. The main contribution of this paper is the proposal of an algorithm to detect malicious CW_min configurations. We show that, for an optimally configured WLAN, our algorithm is effective in avoiding that a user can substantially benefit from maliciously configuring his WLAN station without being detected