這篇論文的重點在於改進WiMAX ASN Anchor Mobility模式的handoff機制。主要方法為減少handoff程序中security context的部份，藉以縮短handoff所造成的delay time。 論文內容裡，首先介紹WiMAX的運作，以及WiMAX security程序。並更進一步地分析ASN Anchor Mobility模式省略security context所發生的問題，以及提出在Anchor BS與Serving BS間轉送封包的加密機制。 根據模擬的結果，“ASN Anchor Mobility Handoff”在handoff delay time的表現上優於“Mobile IPv6 Fast Handoffs over IEEE 802.16e Networks”以及 “Cross Layer Design of Handoffs in IEEE 802.16e Network”。最後並分析AAH模式所增加的負載。 This thesis focuses on the improvement of handoff scheme based on WiMAX ASN Anchor Mobility model. The proposed scheme can decrease the delay time of handoff by reducing the security context message during handoff procedure. In the thesis, the operation flows of WiMAX is firstly described, and then follow the scenario of WiMAX security procedure. Furthermore, by analyzing the issues of ignoring some security context exchange in ASN Anchor Mobility model, the encapsulation scheme is proposed to forwarded the encrypted packets between the anchor BS and the serving BS. In accordance with the simulation results, the proposed ASN Anchor Mobility Handoff scheme has better performance than the“Mobile IPv6 Fast Handoffs over IEEE 802.16e Networks”and “Cross Layer Design of Handoffs in IEEE 802.16e Network” schemes in the handoff delay time. And the overhead caused by the encapsulation is also analyzed.