Group Scheduling for Improving VoIP Capacity in IEEE 802.16e Networks

WiMAX networks are considered efficient for supporting data traffic. However, the VoIP capacity of IEEE 802.16e WiMAX system is not great due to the large MAP overhead caused by dynamic scheduling of VoIP traffic. Persistent scheduling was adopted as a mechanism in IEEE 802.16e Rev2 to reduce this MAP overhead and resulted in a 15% increase in VoIP capacity as compared to dynamic scheduling. While the MAP overhead is reduced, persistent scheduling may cause "resource holes" in the data allocation region of the frame thereby resulting in inefficient resource utilization. This paper proposes a group scheduling mechanism to overcome this problem. The flexibility in resource allocation achieved with group scheduling results in efficient resource utilization within the frame and yet takes advantage of persistence to reduce the MAP overhead. Our simulation results show that our proposal can achieve 22% unidirectional improvement in capacity as compared to dynamic scheduling and 6.5% higher capacity as compared to persistent scheduling.