近幾年來，多媒體服務在無線環境上需求更大的傳輸頻寬，而無線非同步傳輸模式網路(wireless ATM network)可以用來解決這一個問題。無線ATM網路提供了行動台(mobile terminal；MT)能夠在不同的基地台(base station；BS)間移動的特性，但是在支援使用者的移動性的同時，有一個最主要的問題就是在基地台間的移交程序(handoff procedure)。因為ATM是屬於連接導向(connection oriented)的服務方式，所以當移交發生時，在建立新的連線前必須要先尋找出新的路徑，而此過程就稱為再繞徑(rerouting)。迄今，已經有很多用於無線ATM網路上的再繞徑方法被提出。
在本論文中，我們提出了一個適用於無線ATM上的再繞徑方法，針對提出的方法所作的分析，以及不同再繞徑方法的模擬結果。我們比較這些方法的效能，在它們的移交斷訊率(handoff call dropping ratio)、新連線阻塞率(new call blocking ratio)、系統連線拒絕率(system call refusing ratio)、移交延遲(handoff delay)、中斷延遲(disruption delay)、緩衝器需求量(buffer requirement)及頻寬需求量(bandwidth requirement)等項目上。根據模擬的結果，我們的方法可以達到低的移交阻斷率、低的系統連線拒絕率、移交延遲、中斷延遲，並且有效的使用網路資源如緩衝器，頻寬的需求量。

With growing demand for higher bandwidth multimedia services in the wireless domain over the past few years, wireless asynchronous transfer mode (ATM) network has emerged as a fine solution. Wireless ATM network provides mobility support for mobile terminal as the move among base stations. One of the key issues to support user mobility is the handoff procedure between base stations. Because ATM is connection-oriented service, when handoff occurs, it has to find a new route before establishing a new connection, this course is called rerouting. To date, a number of rerouting schemes have been proposed for wireless ATM network.
In this paper, we present a rerouting scheme for wireless ATM network and an analysis of the proposed scheme and simulation results of several rerouting schemes. We compare the performance of these schemes in terms of their handoff call dropping ratio, new call blocking ratio, total call refusing ratio of system, handoff delay, disruption delay, buffer requirement and bandwidth requirement. For the simulation results, our scheme achieves low handoff call dropping ratio, low total call refusing ratio of system, handoff delay, disruption delay and efficient usage of network resources such as buffer and bandwidth requirements.

圖表索引 ……………………………………………………VI
第一章 緒論 …………………………………………………1
1.1 行動通訊簡介 …………………………………………………………1
1.2 無線ATM網路簡介 …………………………………………………3
1.3 研究動機………………………………………………………………5
1.4 章節概要………………………………………………………………6
第二章 無線ATM網路系統 …………………………………7
2.1 無線ATM網路架構 …………………………………………………7
2.2 再繞徑方法概述………………………………………………………10
第三章 改良式混合型再繞徑演算法 ………………………16
3.1 系統架構 ……………………………………………………………16
3.1.1 定義封包長度…………………………………………………17
3.1.2 蜂巢式細胞群集………………………………………………18
3.1.3 流量模型………………………………………………………19
3.2 改良式混合型再繞徑演算法…………………………………………19
3.2.1 演算法流程說明………………………………………………19
3.2.2 演算法實例說明………………………………………………22
3.3 移交信號訊息傳送流程………………………………………………26
第四章 系統模擬與分析 ……………………………………41
4.1 系統模擬參數…………………………………………………………41
4.2 效能評估項目…………………………………………………………43
4.2.1 移交斷訊率..…………………………………………………43
4.2.2 新連線阻塞率………………………………………………43
4.2.3 系統連線拒絕率……………………………………………43
4.2.4 頻寬使用率……………………………………………………45
4.2.5 移交延遲…...…………………………………………………45
4.2.6 中斷延遲……………………………………………………46
4.2.7 緩衝器需求量…………………………………………………47
4.2.8 頻寬需求量…………………………………………………48
4.3 模擬結果………………………………………………………………48
第五章 結論 ……………………………………………………58
參考文獻 ……………………………………………………59

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