當我們提起無線通訊網路，許多為技術陸續被發展出來為了滿足不同使用者對於網路的需求。其中IEEE 802.16e這個標準則是目前最熱門的議題之一，近幾年來許多論文與產品紛紛被發表出來。而當我們在討論行動通訊時，基地台之間換手（Handover）是一個相當關鍵的程序。在IEEE 802.16e標準中，對於如何在周圍基地台（Neighbor BS）中選擇一個最佳的基地台來當作行動用戶台（MSS）的換手對象是一個開放的議題。目前大部分為大家所使用的方式是採用RSSI最強的BS來當作目標基地台，但是能夠提供最強的RSSI訊號的基地台並不一定代表該基地台能夠提供行動用戶台最好的服務。在換手的過程中，除了RSSI之外尚有其他參數可用以輔助決策，例如CINR、relative delay以及可用頻寬（Available Bandwidth）等。本文設計了一個模糊決策系統將這些參數當作輸入來進行最佳目標基地台的選擇，而我們所設計的是一個以服務導向的機制，目的就是要貼近使用者目前使用服務的需求。因此本文針對了不同的服務型態有不同的設計方式。最後我們使用NS-2進行我們的模擬實驗，模擬IEEE 802.16的換手行為並對本文所提出的機制做驗證。

In　wireless　communication　networks,　several　technologies　have　been　developed　to　satisfy　various　needs　when　transmitting　data.　The　IEEE　802.16e　standard　is　one　of　the　most　popular　issues　being　discussed　in　recent　years.　When　we　talk　about　mobile　communications,　handover　is　an　essential　issue.　In　the　handover　decision　procedure　of　the　IEEE　802.16e　standard,　how　to　select　the　best　target　BS　from　neighbor　BSs　for　the　MSS　further　handover　is　an　open　issue.　In　general　way　the　serving　BS　always　chose　the　BS　with　the　strongest　RSSI　as　the　MSS’s　target　BS.　However,　the　most　RSSI　doesn’t　mean　the　BS　have　the　most　resource　or　have　the　best　quality.　There　are　still　other　indicators　to　assist　decision,　such　as　CINR,　relative　delay,　and　available　bandwidth.　We　design　a　fuzzy　decision　system　and　utilize　these　useful　parameters　as　inputs　to　select　the　target　BS　which　can　best　serve　the　MSS.　What　we　propose　is　a　service-oriented　handover　scheme　and　design　different　criteria　according　to　different　service　type.　Then　we　simulate　the　handover　process　in　NS-2　and　verify　our　scheme.

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http://www.antd.nist.gov/seamlessandsecure/download.html