integrating sip and ieee 802.11e to support handoff and multi-grade qos for voip applications
With the increasing popularity of wireless networks and the growing demand for VoIP services, there is a need to guarantee QoS for VoIP calls while supporting as many calls as possible. This paper considers the handoff and QoS issues of VoIP calls under IEEE 802.11e WLANs. Assuming that VoIP calls can be supported by multiple levels of QoS, we show how to conduct call admission control and handoff by integrating SIP and QoS mechanisms of IEEE 802.11e. The proposed scheme is designed to dynamically adjust the resource distribution among existing calls according to the network condition. Multi-level QoS is achieved by adjusting codecs and packetization intervals of calls. The result shows better utilization of bandwidth, decreased blocking rate for new calls, and less dropping rate for handoff calls. In addition, we also show how to achieve early resumption of resources as calls leave a QAP. Simulation result is presented to evaluate the performance of the proposed schemes
ieee 802.11e handoff wireless network quality of service (qos) call admission control (cac) voice over ip (voip) session initiation protocol (sip)