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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60720
標題: | 在分散式動態頻譜存取網路中以自適應跳頻序列尋找鄰近裝置 Neighbor Discovery in Distributed Dynamic Spectrum Access (DSA) Networks Using Adaptive Sequences |
作者: | Chin-Fen Tung 董錦芬 |
指導教授: | 周俊廷(Chun-Ting Chou) |
關鍵字: | 動態頻譜存取,感知無線電,裝置偵測,盲遇,媒體接取層通訊協定,多頻道媒體接取層通訊協定, dynamic spectrum access,DSA,cognitive radio,neighbor discovery,blind rendezvous,MAC protocol,multi-channel MAC, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 隨著雲端運算和機器間通訊的日益發達,對於無線頻譜的需求也越來越大,很快地,無線頻譜將消耗殆盡。動態頻譜存取是一個極有希望能夠解決這樣大量頻譜需求的技術。動態頻譜存取的主要概念是讓次要使用者能夠投機地使用未在使用的付費頻帶。在動態頻譜存取網路中,付費使用者有絕對的權力使用其付費頻帶。次要使用者可能會因付費使用者無預警地佔領頻帶而被迫立刻停止傳輸。這對於被打斷傳輸的次要使用者來說,他們是沒有時間溝通要到哪一個通道繼續傳輸的。就算它們能夠跳到一樣的通道,但這個新通道也可能被付費使用者所佔領,這樣被打斷傳輸的次要使用者還是無法找到彼此。因此,一個可靠的方法讓次要使用者能夠快速發現彼此是很重要的。
在本論文中,我們使用以序列為基礎的協定來實現在動態頻譜存取網路中使次要使用者能夠發現鄰近裝置。我們提供了兩個以序列為基礎採用自適應序列設計的方法,且不需要事先的同步及溝通就能夠解決在動態頻譜存取網路中尋找鄰近裝置的問題。我們提出的兩個方法,在至少存在一個一對傳輸對的兩個裝置都認為是可以使用的通道的前提下,保證一對傳輸對一定可以找到對方。因為我們的方法是用自適應的序列設計,所以次要使用者可以多跳到沒有付費使用者的通道更多次,這樣的話我們就可以得到較高的通道使用率及較低的平均遇到時間。不管是分析或是模擬結果都顯示我們的方法比現有的多種方法能夠達到較佳的表現。 With rapid growth in cloud computing and machine-to-machine communications, demands for wireless transmission increases exponentially and soon will exhaust the wireless spectrum. Dynamic spectrum access (DSA) is one of the promising technologies to address such fast-growing demands. The main idea of DSA is to enable radio devices to search for underutilized spectral bands and utilize them on an opportunistic basis. In a DSA network, channel access is subject to the usage of licensed users. DSA devices could be forced to vacate a channel without any notice in advance. Therefore, determination of a new channel via negotiation may not be possible. Even if the devices switch to the same channel, they may be unable to access that channel if it happens to be occupied by licensed users. The devices may then lose contact with each other and their communication could be interrupted inde finitely. Therefore, how to ensure DSA devices to (re)discover each other in a timely and reliable manner is the most challenging task for providing seamless communication in a DSA network. In this thesis, sequence-based protocols are considered to realize neighbor discovery in DSA networks. We provide two sequence-based schemes that adopt the adaptive sequence design and require no sequence-level synchronization or prior negotiation. The proposed two schemes guarantee that a transmission pair can find each other as long as they have at least one commonly available channel. Thanks to our adaptive sequence design, unlicensed users access available channels more frequently and thus a higher utilization and a lower average rendezvous time could be achieved. Both analytical and simulation results show that the proposed two schemes outperform many existing sequence-based schemes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60720 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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