| Summary: | 碩士 === 國立交通大學 === 多媒體工程研究所 === 98 === IEEE 802.16 (WiMAX) is becoming one of the popular technologies in wireless communications. Multi-hop relay station (RS) is used to extend the coverage area in IEEE 802.16j. Mobile RS (MRS) is a relay station that is used while in motion. A MRS mounted on a vehicle is a special application case for the research in this thesis. The MRS provides a fixed access link to the end mobile terminals riding on a vehicle. In order to maintain the security of wireless communications, re-authentication should be considered when the mobile station (MS) performs handover. However, it usually wastes too much time that may interrupt higher layer applications during a handover.
When a MS moving together with MRS changes BS for higher signal quality or better QoS, it performs network layer handover procedure while MRS performs link layer handover procedure. In this thesis, we proposed a pre-authentication scheme to reduce the interruption time of link layer handover by performing the authentication procedures before the MS roams to another BS. We developed a simulation experiment to evaluate our scheme. The result shows that with Fast Mobile IPv6, our scheme is able to reduce the interruption latency efficiently both in predictive mode and reactive mode, as well as reduce the packet loss rate in predictive mode.
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