| With the fast development of wireless networks technology and Internet technology, it becomes natural for users to expect to access the Internet at any time and from any where, and to remain connected and continue to use the networks as they move about. CDMA2000, as one of main 3rd generation mobile communications technologies, can offer high-rate data wireless access and meet users' needs of wireless access, but it solves handoff in data link layer, thus it will face many problems in its handoff process, such as larger handoff delay and vertical handoff.Mobile IP protocol has been designed to support mobile nodes operating in the Internet by IETF, and it can handle the handoff problem in network layer. Mobile IPv6 has many advantages, such as auto allocation and security, thus it will extremely useful to settle the handoff deficiency in CDMA 2000. When Mobile IPv6 executes the MNs' mobility administration, handoff QoS is one of the most important problems of affecting the administration, so it is urgent to improve its handoff QoS.Based on analysis of mobile IPv6 handoff methods in CDMA2000 system, the paper analyzes two problems occurring in the handoff: handoff performance and QoS support. Firstly, it researches on the handoff schemes used in Mobile IPv6. Secondly, a QoS-based handoff scheme, namely the combination of HMIPv6 and QoS object, is presented and emphasized, including the handoff process in the network layer and further considerations for the process.The QoS-based handoff scheme enables the mobile node to choose among a set of available Access Points flexibly and search for a route which offers satisfying QoS. With people's rising requirements for services, this kind of handoff scheme will be highly valued for it offers QoS guarantees for the moving users. |
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