Research And Implementation Of Quick And Seamless Handoff Scheme In The Mobile WiMAX System

For the next generation wireless communication network system, the design and implementation of the fast seamless handoff algorithm is a key factor. A new broadband wireless access, World Interoperability for Microwave Access,called WiMAX, has been specified in the IEEE 802.16e standard document, to provide the higher bandwidth and the larger coverage area compared with the IEEE 802.11 based wireless networks. In the IP based mobile network, Mobile IPv6 (MIPv6) protocol provides the binding update message to update the mobile station's IP information for supporting the layer 3 mobility. Hierarchical Mobile IPv6 (HMIPv6) protocol is proposed by employing a hierarchical network structure to reduce handoff latency. However, HMIPv6 protocol suffers a long handoff delay and the high packet loss in the macro mobility.This paper presents a new cross-layer partner-assisted handoff mechanism based on HMIPv6, termed PHMIPv6 protocol. The PHMIPv6 protocol is a cross-layer approach by the combination of layer 2 and layer 3. The partner station (PS) is a new component with relay ability and adopted by our protocol. With the assistance of the PS, care-of address (CoA) is pre-acquired and DAD operation is pre-executed by the PS before the MS initiates the layer 2 handoff. Then the simulation of the scenario of each protocol is performed on a software called NS2(Network Simulator). The simulation results show that PHMIPv6 protocol actually achieves the performance improvements in handoff delay time, packet loss rate, and handoff delay jitter.