- 學位論文
802.16e快速換手機制之改善
A New Scheme for 802.16e Fast Handover Strategy
摘要
在Intel公司的積極主導下所成立的WiMAX Forum，為了解決傳輸功率、範圍以及支撐高速多媒體服務上的需求，發展出使用了BWA (Broadband Wireless Access)系統的無線都會區域網路技術IEEE 802.16。IEEE 802.16擁有了傳輸速度可達70Mbps、覆蓋範圍可達30英哩、QoS (Quality of Service) 以及頻段授權等條件，更衍生出擁有移動性標準的IEEE 802.16e。IEEE 802.16e的技術主要以換手與能源節省兩大機制為主，而換手就是MS(Mobile Station)從Serving BS(Base Station)移動到Target BS所必須執行的動作，其中換手動作最主要的重點就在於解決封包遺失以及封包延遲所導致的問題。 在這篇論文中，我們將RFC 5270 標準中的Predictive模式加以改善，論文中所提議的方法是改進第二層與第三層中的訊息傳送步驟，使得第二層與第三層的換手能夠同時進行，將兩層的封包延遲時間縮短。同時，我們將採用所有Neighbor BS的BS_Group_ID來做比對，確認其是否在同一個網域中，減少第三層多餘的換手動作。由模擬中，證實我們的策略能節省可觀的延遲，大幅改良系統效能。
並列摘要
Under the leading of Intel Corporation, WiMAX Forum develops IEEE 802.16 with BWA (Broadband Wireless Access) system. IEEE 802.16 possesses transmission speed up to 70Mbps, covers 30 miles wide with QoS (Quality of Service) and authorization, and stretches IEEE 802.16e as mobile standard. The core techniques of IEEE 802.16e are energy saving and handoff which indicates switching MS (Mobile Station) from Serving BS (Base Station) to Target BS. The significance of handoff is to resolve the problems of packet missing and delay. The essay will improve Predictive mode on RFC 5270 by shortening message delivery steps between level 2 and level 3, which makes handoff could be proceeded on the same level. Meanwhile, the essay will compare all BS_Group_IDs of Neighbor BS to avoid unnecessary handoff on level 3. From the result of simulation, we can find that the improvement is significant.