Chung Gu Kang

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

This paper proposes effective polling scheme to control a polling interval adaptively 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 is serviced in the frame or not is decided by relationship between poling 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 is 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.

Wireless access burst scheduling discipline supporting integrated services in wireless ATM networks

In this paper, we propose a layered access control protocol, which incorporates a dynamic polling scheme on a burst level into the fair cell scheduling (polling-based wireless access burst scheduling: P-WABS) algorithms. Both the real-time and non-real-time multimedia services can be efficiently supported under the framework of the layered access control in the wireless ATM networks. Since it provides a contention-free access control mechanism, it turns out to be adequate for the multimedia services with the real-time constraints. Multimedia service traffic, including the constant bit rate (CBR), real-time variable bit rate (rt-VBR) and available bit rate (ABR) services, is considered to analyze the proposed scheme. Simulation results show that the proposed approach significantly improves the cell loss performance of rt-VBR services while a reasonable level of fairness is achieved for the ABR services.