臺灣博碩士論文加值系統

本篇論文中，我們研究在感知無線電網絡(cognitive radio network)中使用能量偵測進行合作式頻譜感測，將不同感知使用者所觀察到的訊號能量值結合後做資料整合(data fusion)評估偵測機率(probability of detection, P_d)與錯誤警報機率(probability of false alarm, P_f)。感知無線電中最大比率結合(maximum ratio combining, MRC)方式在低訊雜比(signal-to-noise ratio, SNR)情況下被證明是比等增益結合(equal gain combining, EGC)方式優良的。先前研究提出的中繼點選擇機制為選取傳輸路徑上有最大瞬時SNR的中繼點再用EGC將直接傳輸路徑收到的訊號做結合。在這裡，我們提出一個較佳的中繼點選擇機制，用MRC與EGC結合後再與先前研究做比較，進行數值模擬。結果說明我們的中繼點選擇機制能有效提高偵測機率與降低錯誤警報機率。

In this thesis, we consider cooperative spectrum sensing based on energy detection in cognitive radio networks. The signal energy values observed by different cognitive users will be combined by data fusion to assess probability of detection and probability of false alarm. At low signal-to-noise ratio (SNR), the maximum ratio combining (MRC) method proves to be better than equal gain combining (EGC) method in cognitive radio networks. Previous studies have presented that a relay selection scheme with maximum instantaneous SNR on its transmission path is selected and it is combined with direct transmission paths by EGC. Here, we propose a better relay selection scheme which incorporates MRC and EGC, and compare its simulation with previous studies. Our results indicate that the relay point selection mechanism can effectively improve the probability of detection and reduce probability of false alarm.

摘要 I
Abstract II
目錄 III
圖目錄 IV
表目錄 VI
第一章 緒論 1
1.1　前言 1
1.2　研究目的與動機 3
1.3　論文架構 4
第二章 研究背景 5
2.1　感知無線電技術 5
2.1.1　感知無線電概述 5
2.1.2　感知無線電網路架構 8
2.2　頻譜感測 12
2.3　合作式頻譜感測 15
2.3.1　合作式通訊中繼點協定 17
第三章 合作式中繼點選擇 19
3.1　系統模型 19
3.2　能量偵測法 21
3.3　最大比率結合與等增益結合 25
3.3.1　直接傳輸路徑訊號的平均值和變異數 28
3.3.2　MRC結合中繼點轉傳訊號的平均值和變異數 29
3.3.3　EGC結合中繼點轉傳訊號的平均值和變異數 30
3.3.4　偵測機率與錯誤警報機率 31
3.4　中繼點選擇機制 32
第四章 模擬與分析 35
第五章 結論 43
參考文獻 45

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