Capacity Improvement of WDB Algorithm for Voice Service over WLAN

As the integration of prevailing voice over Internet protocol (VoIP) technology and wireless local area network (WLAN), voice over WLAN (VoWLAN) is expected to experience a dramatic growth in the near future. However, increasing voice capacity of the system still remains a problem. In this paper, the voice capacity of "waiting-time dependent backoff (WDB)" algorithm proposed in our previous work is investigated. WDB controls backoff window (BW) according to waiting-time (WT), and staggers BW ranges among priorities. The algorithm is embodied by a flexible mathematic model consisting of deterministic function and random function. Simulation results show that WDB can maintain acceptable levels of QoS for more VoIP calls, thus increase the overall VoIP capacity both with and without background traffic.