在IEEE 802.16無線通訊標準中，IEEE 802.16e是為支援可移動性的服務所產生的。在支援可移動性服務的狀況下，基於使用者的移動情形，與基地台之間的信號強度變化情形，更換基地台是必然的現象，而換手技術(handover)乃為其中的關鍵，基於IEEE 802.16e及行動式Mobile IPv6的跨層換手協定的研究，如何整合第二層MAC Layer與第三層IP Layer的換手機制，縮短換手所需的延遲時間，確保資料的及時送達，才是研究的目標。
在本文中，利用結合SIP (Session Initiation Protocol)，IP層和IEEE 802.16e的MAC層作連結，採用事先取得DHCP Server提供的新IP位址(Pre _ DHCP)及資料傳送(data buffering/forwarding)跟限定MAC層的啟動時機等方法，來降低換手所需的時間，與確保資料的及時性與完整性。

IEEE 802.16e is the mobile standard and supporting of IEEE 802.16. Since the mobility of end point equipment (Mobile Station), the RF signal between Mobile Station and Base Station is changing during the movement. The handover between serving Base Station and Mobile Station is necessary and is the key technology for mobility. In the IEEE 802.16e and Mobile IPv6 environment, how to integrate the handovers of MAC Layer and IP Layers, how to decrease the handover delay, and how to secure the delivery of data stream are the focus in the study.
We propose a fast handover scheme to improve the cross-layer handover in the IEEE 802.16e (MAC Layer), Mobile IPv6 (IP Layer), and SIP (Application Layer) environment. The proposed handover scheme includes IP/MAC handover trigger, Fast Handover Mobile IPv6 and data buffering and forwarding. The proposed scheme can reduce the delay time of handover and secure the SIP data stream.

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