感知無線電網路下頻譜偵測策略之再思考

Revisiting the Detection Strategy for Spectrum Hole Discovery in Cognitive Radio Networks

劉坤星(Kun-Hsing Liu)

指導教授 ： 謝宏昀

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.02123

摘要

感知無線電設計的主要目的為增進頻譜的使用效率，因此如何偵測尋找可用的頻譜，並在不干擾持照使用者(licensed user)的前提下使用頻譜，便成為一個很重要的議題。傳統的頻譜偵測技術著重於最小化偵測失誤的機率，但是這樣的做法卻會造成頻譜的使用效率無法有效提升。其主要原因是沒有考慮到偵測失誤未必會造成干擾：當感知無線電使用者和執照使用者的距離相對較遠時，即使感知無線電使用者因為收到來自持照使用者的訊號較弱造成偵測失誤而使用了該頻譜，但由於持照使用者收到來自感知無線電使用者的訊號也相對較弱，因此兩者同時使用頻譜並不會造成太大的干擾問題。為了彌補傳統頻譜偵測策略的不足，我們提出了一個新的頻譜偵測策略，將干擾的機率納入偵測指標，並在最大化感知無線電網路的頻譜使用率下，確保在偵測失誤時感知無線電使用者對持照使用者造成的干擾小於系統的規範。為了驗證這樣的頻譜偵測策略效能，我們首先考慮在一組感知無線電傳送及接收用戶下進行頻譜偵測時頻譜使用的效率。我們發現，考慮到干擾機率的頻譜偵測策略，在一組感知無線電用戶的情況下，確實對頻譜使用率有所提升。但是隨著保護程度愈趨嚴格，頻譜的使用率卻有可能會隨著錯誤警報的上升而下降。不過，透過多組感知無線電用戶間的合作式偵測，可以有效解決這個問題，提升頻譜使用率。但由於結合網路中所有組別偵測結果所做的決策，不一定能達到最佳的頻譜使用率，因此我們同時考慮分群的合作式偵測，並透過同盟式賽局的模型來模擬感知無線電用戶的分群。綜合模擬的結果，我們發現考慮到干擾機率的頻譜偵測策略，不管在一組、多組或多群感知無線電用戶進行頻譜偵測，確實都有較傳統頻譜偵測策略為高的頻譜使用率。

關鍵字

感知無線電網路 ； 頻譜偵測

並列摘要

ognitive radio designed primarily to promote the efficient use of spectrum. Hence, how to detect and search spectrum hole without causing interference to licensed users becomes an important issue. Conventional detection techniques focus on minimizing missed detection probability, but this way can't effectively improve channel usage. The major reason is that secondary users may not cause interference to primary user when missed detection occurs: while secondary user is far away from primary users, secondary user makes a missed detection due to small received primary signal strength and use the same channel, but they will not cause interference to each other while they use the same channel meanwhile, because licensed users also receive small secondary signal strength. To compensate for the deficiencies of conventional detection techniques, we propose a new detection strategy, that is interference-awareness, and the goal is to maximize spectrum hole discovery under a certain protection.

Abstract To verify the effectiveness of interference-aware detection strategy, we first consider one cognitive transmission pair. From simulation results, we obtain that this kind of detection strategy indeed efficiently improve spectrum hole discovery. But with the increasingly strict level of protection, spectrum utilization has the potential to decrease with increasing false alarm. However, cognitive radio users through cooperative detection, can effectively solve this problem, enhance the spectrum utilization. We furthermore obtain that it's not the optimal solution by fusing all sensing results in the network, hence, we propose a group-based cooperation method, and use coalition game to model it. From simulation results, we obtain that considering interference-aware detection strategy indeed improve the spectrum hole discovery for one transmission pair, cooperative and group-based spectrum sensing.

並列關鍵字

Cognitive Radio Networks ； Spectrum Hole Discovery

參考文獻

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