Non-uniform polling scheme with activity detection for real-time services in wireless WLAN

This paper proposes effective polling scheme to control a polling interval adoptively by considering the characteristics of real-time traffic and delay constraint. In this scheme, the initial polling token generation time of each source is set as the polling interval of each source, and whether source i is serviced in the frame or not is decided by relationship between polling token generation time and frame length (T). The proposed scheme adjusts the polling interval dynamically, considering delay bound whenever AP detects the inactive transition of sources. The attractive feature of the proposed scheme is that it uses contention-free based mechanism for activity detection of real-time traffic and simultaneously revised polling token generation time used for activity detection can guarantee the delay bound of real-time traffic, still conforming to IEEE 802.11 standard. Therefore this method improves inefficiency of legacy contention or contention-free based activity detection scheme. Also the proposed mechanism increases system capacity through reduction of unnecessary delay caused by the transmission of polling message when a mobile station has no packet to be transmitted. Our simulation study demonstrates that capacity of the real-time traffic can be increased considerably.