張進福Chang, Jin-Fu臺灣大學:電信工程學研究所何慶哲Ho, Ching-CheChing-CheHo2010-07-012018-07-052010-07-012018-07-052008U0001-2907200806310600http://ntur.lib.ntu.edu.tw//handle/246246/188181WiMAX系統(也稱做802.16)為新一代的無線寬頻接取網路，規格中將現今最新潮先進的行動通訊技術訂立其中，而在其所訂立的行動版本中，新增了使用裝置的行動支援，讓行動多媒體應用具有更多的可能性，本研究也本著此規格所著重的行動性，而將重點放在研究行動通訊系統中的換手技術，換手技術是行動式通訊系統很重要的一個環節，若是無法處理得當的話，往往使用者便會感到不耐，在本文中我們會對802.16e所訂立的換手程序做一個詳細的介紹，並且仔細分析其中各個步驟對於換手延遲時所造成的影響，除此之外，本研究假設了一個環境，此環境的基地台大部分為網狀模式的網狀基地台，其中大部分基地台並無法直接取得網際網路上的資訊，而必須經由路由的程序才可以與此區域中的系統基地台連線進而取得網際網路上的資訊，此特殊環境的設定是考量到在城市或是在深山偏遠地區，若要布建網路需要花費大量的成本，而且有些地方重新布建實體網路實屬不易，所以我們才會設定此網狀基地台環境，本研究將802.16e中的各項換手機制套用在此環境上，並且發現網狀基地台環境中路由延遲對於各個換手機制均造成很大的效能衰退，所以我們提出了一個簡單的機制，改善這之中某些換手機制在網狀基地台環境下的換手失敗率效能，並在最後一章對於觀察到的現象作結論與心得建議。Mobile WiMAX followed the 802.16e standards provides broadband services with high mobility capability under wireless environment. Handover is an essential function for every mobile communication systems and users suffer handover failure due to handover process and channel resource. WiMAX operates under two modes : PMP (Point to Multi-point) mode and Mesh mode. Mesh mode provide the networks with larger data coverage, subscriber stations and Base stations in mesh mode have self-configured and self-organized capabilities. Mesh mode in WiMAX reduce the cost of constructing a network in metropolitan area or in rural area due to its radio access characteristic for Base stations. In this thesis, we only focus on the environment with mesh base stations, the mobile subscriber stations use PMP mode to access services. In this way, the handover procedures are extended to execute routing process to the base stations which connect to Internet after the regular handover procedures finished. Therefore the handover time will be longer to increase the failure rate. Different handover mechanism (hard handover and soft handover) are discussed in this thesis, we founded that routing delay due to mesh base stations environment dominates the handover failure rate in some handover types. There is a comparison of handover performance in standard environment and in mesh base stations environment. To reduce the effect of routing delay, this thesis propose a simple method to make the neighbor base stations do the routing procedure in advance, and the simulation result show it works.誌謝 i文摘要 iii文摘要 v目錄 x目錄 xii一章........................................1 緒論.......................................1.1前言.......................................1.2 行動通訊系統發展歷史簡介..................3.3 802.16系統簡介...........................7.4 802.16 網狀網路簡介.....................14.5 研究動機.................................23.6 論文架構.................................23二章.......................................25式換手在802.16網狀網路下之效能表現探討.....25.1 802.16 硬式換手機制簡介.................25.1.1 換手目的...............................25.1.2 網路進入程序(Network Entry Procedure)..26.2 換手程序................................33.2.1服務細胞重新選擇(Cell reselection)......33.2.2換手決定和啟動(Handover decision and initiation)..34.2.3對目標基地台進行同步(Synchronization to the target BS).....................................34.2.4與目標基地台執行測距 (Ranging with target BS).....35.2.5與之前服務的基地台結束連線服務Termination of context with previous BS..................................35.3 換手分析.................................39.3.1 同步延遲(Synchronization delay)TSyn.....39.3.2 測距延遲(Ranging delay)TRng.............40.3.3 認證延遲(Authentication delay)TAuthen...44.3.4 註冊延遲(Registration delay)TReg........45.3.5 單播延遲(Unicast delay)TUnicast.........45.4 硬式換手在802.16網狀網路下之效能分析.....45.4.1 環境設定................................45.4.2 相關參數................................48.4.3 網狀網路下基地台重新路由所造成重新路由延遲的換手流程示意圖..........................................51.4.4 模擬結果................................54.5 本章小結..................................58三章.................................................59式換手在802.16網狀網路下之效能表現探討...............59.1巨分集換手 MDHO (Macro Diversity Handover)..........59.2快速基地台轉換 FBSS(Fast Base Station Switch).......61.3在FBSS和MDHO之下由於網狀網路環境所造成的影響........62.3.1 巨分集換手MDHO...................................62.3.2 快速基地台轉換FBSS...............................63.4巨分集換手與快速基地台轉換在網狀基地台下之效能分析..66.5本章小結............................................68四章.................................................69對軟式換手在802.16網狀網路下之效能改進討論...........69.1快速基地台轉換(FBSS)在網狀基地台環境之效能改善方法..69.2改良式快速基地台轉換(FBSS)在網狀基地台環境之效能表現71.3本章小結............................................75五章.................................................77結與未來研究.........................................77考文獻...............................................803174995 bytesapplication/pdfen-US802.16802.16e全球互通微波接取網狀基地台換手WiMAXMesh Base stationHandoverthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188181/1/ntu-97-R95942053-1.pdf