預取換手資訊之WiMAX換手機制:系統設計與實測

Context Prefetching for WiMAX Handover:System Design and Testbed Experiments

林柏宏(Po-Hung Lin)

指導教授 ： 魏宏宇

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01090

摘要

全球互通微波存取 (WiMAX) 從IEEE 802.16d演進到IEEE 802.16e之後開始支援了行動通訊服務，因此換手機制也變得相當重要，由於目前的換手機制是由使用者端主動發起，而換手期間包含了準備期和行動期，當使用者端發現訊號強度不好時，會發送換手要求給服務基地台，服務基地台此時進入準備期並需要透過存取網路服務閘道器 (ASN-GW) 跟其餘的基地台做溝通，會花相當多的時間，因此我們設計的方法為讓服務基地台在使用者端送換手要求過來之前先提早跟後端其餘的基地台做溝通，等到使用者端送換手要求過來之後，可以立即回覆此要求並快速進入行動期，讓使用者在訊號強度變差之前可以快速換手到另外一台訊號比較好的基地台，此外也提出讓基地台主動提早開始跟後端做換手溝通的三種啟動方式。 此篇論文主要的貢獻在於實作以上換手機制並運作在資策會所開發的WiMAX基地台上面，來縮短WiMAX基地台的換手時間。

關鍵字

WiMA ； 換手 ； 實測平台

並列摘要

Worldwide Interoperability for Microwave Access (WiMAX) is commonly used to refer to a collection of standards, products, and service offerings derived from the IEEE 802.16 family of standards. According to the IEEE 802.16e--2005, WiMAX begins to support for the mobile clients. As a consequence, the support for handover is necessary and becomes an important issue. The handover mechanism in our WiMAX Base Station (BS) uses hard handover scheme and it is a MS--initiated handover, which the handover event is triggered by Mobile Station (MS). We implement our context prefetching handover mechanism on the WiMAX BS testbed which is developed by Institute for Information Industry (III) to improve the handover performance. The main idea is that we enable the serving and target BSs to do the context retrieval and the data path pre--registration in preparation phase in advance before MS sends the handover request to BS. We also propose three triggering mechanisms to trigger the WiMAX BS to do the context prefetching in the original preparation phase. Our main contribution is implementing our proposed handover mechanism on the WiMAX BS to enhance the handover performance.

並列關鍵字

Handover ； IEEE 802.16e ； testbed Implementation

參考文獻

[1] IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface

for Fixed Broadband Wireless Access Systems. IEEE Std 802.16-2004 (Revision of

IEEE Std 802.16-2001), 2004.

[2] IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface

[3] Sayan Kumar Ray, Krzysztof Pawlikowski, and Harsha Sirisena. Handover in Mobile