Adaptive Contention Resolution for VoIP Services in the IEEE 802.16 Networks

In the IEEE 802.16 networks, a subscriber station can use the contention slots to send bandwidth requests to the base station. The contention resolution mechanism is controlled by the backoff start/end values and a number of the request transmission opportunities. These parameters are set by the base station and are announced to subscriber stations in the management messages. In the case of the VoIP services, it is critical that the contention resolution occurs within the specified time interval to meet the VoIP QoS requirements. Thus, it is the responsibility of the base station to set correct contention resolution parameters to ensure the QoS requirements. This paper presents analytical calculations for the parameters that control the contention resolution process in the IEEE 802.16 WiMAX networks. The simulation results confirm the correctness of theoretical calculations. They also reveal that the adaptive parameter tuning results in a better resource utilization when compared to the static configuration. At the same time, all the delay requirements are ensured.