隨著無線網路的技術與日俱增，各種行動通訊的設備及應用也跟著蓬勃發展，對於頻譜資源的需求業日漸增加，使得資源也變得相對寶貴。近年來，美國電機電子工程學會(IEEE)和美國聯邦通訊委員會(FCC)皆致力於發展感知無線電網路及制定標準規格。除此之外，美國聯邦通訊委員會也於去年十一月投票通過開放電視播送頻道(Broadcast TV Band)間的空白頻譜(White Space) ，此舉更讓寬頻技術往前躍了一大步。 然而，感知無線電網路是使用授權頻段(Licensed channel)間的空白頻譜及未授權頻段(Unlicensed channel)來提供服務。因此，當授權頻段的主要使用者(Primary user)出現就必須將離開原來頻段跳至另外可用的頻換，這樣的過程稱為頻譜換手(Spectrum handover)。頻譜換手時有可能會造成傳輸中斷，讓傳輸服務品質(Quality Of Service)及感知無線電網路系統效能下降。 本論文提出在頻譜換手時提供佇列(Queue)讓感知無線電使用者在沒有空白頻段使用時服務不會馬上被中斷且也使用保護頻段(Guard Channel)減少換手使用者的阻絕機率(Blocking Probability)以提供無縫換手機制。最後使用馬可夫鏈分析應證所提出的方法。The wireless network technology has significant progress and various mobile communication equipment and applications also become more and more. Demand of spectrum resource is increasing, therefore spectrum resource is valuable relatively. In recent years, IEEE and FCC are currently developing wireless network standards related to the cognitive radio network technology. In addition, the FCC opening the broadcast television band’s white Space by voted in November 2008 , that let the broadband technology proceed to lead a new . However, cognitive radio network offered service by used white space in television broadband or the unlicensed channel. When the primary user appears, CR user vacate the channel and change to another free channel, it is called “spectrum handover’’. Spectrum handover may interrupt transmission, decrease QoS and system performance. This thesis address a seamless spectrum handover mechanisms which offered Queue to CR user for waiting to keep service not interrupt immediately and Guard channel to decrease the blocking probability. Performance results are analyzed by Markov Chain.
