為了解決頻譜資源不被有效利用的情況，我們使用感知無線電(Cognitive radio；CR) 技術於無線通信以提高頻譜效率。經過偵測頻譜空洞，讓感知用戶有效地使用授權頻段，以提升頻譜資源使用效率。
本論文模擬感知無線電系統，使用多天線技術合作式頻譜偵測，利用多天線於多個感知中繼端(cognitive relays)進行能量偵測並使用波束成形接收訊號以及決策融合(decision fusion)策略，再將所收到的資料利用多天線技術傳給資料整合中心(fusion center；FC)，使用位元映射對齊技術(Bit Mapping Alignment Technology)計算系統偵測效能。根據模擬結果，本論文所提出的方法相比以往的頻譜偵測效能更好，並以天線個數和中繼端數量的不同做出模擬與比較。

Cognitive Radio (CR) technique is proposed to enhance the spectrum efficiency by detecting the spectrum holes so that the users may utilize the licensed spectrum. In this thesis, CR is simulated by using the cooperative spectrum detection with multi-antenna application on cognitive relays for energy detection. Beamforming is also used for signal reception and decision fusion. The received data is sent to the data fusion center by multi-antenna technique, and the system detection efficiency is calculated by bit mapping alignment. According to the simulation results obtained, the proposed method in this thesis achieves better performance than previous spectrum detection methods under various number of antennas and relays.

目錄
中文摘要 I
Abstract II
誌謝 III
目錄 IV
圖目錄 VII
表目錄 IX
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機 3
1.3 研究目的 4
1.4 論文架構 5
第二章 感知無線電 7
2.1 背景 7
2.2 感知無線電系統 9
2.3 感知無線電技術 12
2.4 頻譜感測 14
2.4.1　傳輸端感測 15
2.4.2　能量偵測器 16
第三章 多天線系統 19
3.1　多天線系統 19
3.1.1 多天線系統架構-前端 20
3.1.2 多天線系統架構-後端 21
3.2　感知中繼端 25
3.3　波束成型(Beamforming) 26
3.4　天線分集系統 29
3.4.1選擇性結合(Selection Combining) 30
3.4.2平方律結合(Square Law Combining) 31
第四章 合作式頻譜偵測 33
4.1　合作式頻譜偵測簡介 33
4.2　決策融合 34
4.3　位元映射對齊技術 36
4.3.1　位元映射對齊預編碼設計 37
4.3.2　解調方式 38
4.4　最大似然估測法 41
第五章 模擬與分析 43
5.1　感知中繼端模擬 43
5.2　多感知中繼端之合作式頻譜偵測模擬 47
第六章 結論 53
6.1　結論 53
參考文獻 55

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