The basic mechanism of HCCA (HCF Control Channel Access) has been introduced in IEEE 802.11e standard to support the parameterized QoS by allocating a fixed duration based on the requested TSPEC requirements during the admission control process. However, the variable bit rate (VBR) traffic (e.g., MPEG-2 and MPEG-4 video) cannot be surely supported. In this study, the adjustable TXOP mechanism for supporting video transmission, ATMV, has been proposed. The mechanism adaptively adjusts the TXOP duration according to a finite state machine based on feedback queue size information. The mechanism aims for prompt serving burst packets, generated from the incoming video frames, which finally minimizes the packet delay. Both system performance (mean packet delay, TXOP loss factor, and channel occupancy) and video quality (PSNR and MOS values) have been evaluated from five video clips in three categories by using the network simulator, NS2, with EvalVid toolset. The results reveal that the proposed mechanism performs well for rapid movement video category and adequately supports for other video categories.

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Traditional rogue access-point (AP) detection mechanisms are employed in network administration to protect network infrastructure and organization; however, these mechanisms do not protect end users from connecting to a rogue-AP. In this paper, a rogue-AP detection technique on the mobile-user side is proposed. By using a simple method involving walking, the round-trip time (RTT) and the modulation and coding scheme values are obtained, and a more accurate transmission rate for particular RTT values is thereby calculated. Further, the cleansed data are classified using the k-means method and the cumulative distribution function for the detection process. The results demonstrate that a rogue-AP can be detected with an F-measure value of up to 0.9. In the future, the proposed algorithm can be implemented as an application installed on mobile devices so that nontechnical users can detect rogue-APs.