目前的頻譜使用一直是呈現一個不平均使用的狀態，所以我們更需要感知無線電(Cognitive Radio；CR)來找尋頻譜空洞(Spectrum holes)，有效地使未授權的使用者善用授權頻段，減少頻譜空閒的時間，讓頻譜能夠充分的被使用。
本論文為模擬感知無線系統，主要使用WINNER II路徑損失(Path Loss)模型進行模擬，以合作式頻譜偵測(Cooperative Spectrum Sensing)的方式，在主要使用者(Primary User)至感知中繼端使用天線分集(Antenna diversity)的方式觀察誤報機率(probability of false alarm)和偵測機率(probability of detection)，而在感知中繼端至融合中心(Fusion Center)採用中繼補助(relay-assisted)的方式，離融合中心較遠的感知中繼端可以透過其他的感知中繼端將決策資料訊號回傳至融合中心，降低感知中繼端至融合中心之間傳輸的位元錯誤率(Bit Error Rate)，接著在決策融合(Decision Fusion)中採用AND和OR以及Majority法則，藉此提升決策融合的正確性。

The current status of spectrum usage has been an uneven allocation, so we are in more urgent need of Cognitive Radio (CR) which is proposed to probing for spectrum holes to effectively make unlicensed users access the licensed bands so the idle periods of spectrum can be cut down. Hence, the spectrum bands will be effectively utilized.
In this thesis, WINNER II path loss model is applied as an example for the simulation of wireless system. By using the antenna diversity, the cooperative spectrum sensing observes the probabilities of false alarm and detection between the primary user and cognitive relays. Then, a relay-assisted method over cognitive relays is applied to enhance the received signals in fusion center so that some signals in cognitive relays farther from fusion center can be relayed through the nearer cognitive relays and the overall bit error rate in fusion center can be improved. Finally, the decision fusion with different rules including AND, OR and Majority is applied to improve the accuracy of decision fusion.

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 10
2.3 感知無線電技術 13
2.4 頻譜偵測 15
2.4.1 傳輸端偵測 16
2.4.2 能量偵測器 17
第三章 多天線技術 21
3.1 多天線系統架構 21
3.2 感知中繼端 22
3.2.1 主要使用者到感知中繼端傳輸 22
3.2.2 感知中繼端之間傳輸 23
3.3 感知中繼端天線分集系統 25
3.3.1 最大比值合併 26
3.3.2 等增益合併 27
3.3.3 選擇性合併 28
第四章 合作式頻譜偵測 29
4.1 合作式頻譜偵測系統架構 29
4.2 感知授權網路 31
4.2.1 感知中繼端頻譜偵測 32
4.3 偵測網路 33
4.3.1 最大似然估測法 34
4.3.2 BPSK的最大似然估測法 35
4.3.3 QPSK的最大似然估測法 38
4.4 決策融合 39
4.5 合作式頻譜偵測的路徑損失 42
第五章 模擬與分析 45
5.1 感知中繼端的天線分集比較 46
5.2 合作式頻譜偵測模擬流程 50
5.2.1 偵測網路通道錯誤率之比較 53
5.2.2 集中型與中繼補助型的決策融合之評估 56
5.3 感知網路距離關係與決策融合之評估 59
第六章 結論與未來展望 61
6.1 結論 61
6.2 未來展望 61
參考文獻 62

[1] M. A.McHenry, “NSF spectrum occupancy measurements project summary,” Shared Spectrum Company, August 2005.

[2] Rahul Tandra, Shridhar Mubaraq Mishra, and Anant Sahai “What is a Spectrum Hole and What Does it Take to Recognize One?” Proceedings of the IEEE, vol.97,no.5, pp.824-848,May 2009.

[3] L. Khalid, A. Anpalagan, “Emerging cognitive radio technology: Principles, challenges and opportunities,” Computers & Electrical Engineering, vol.36, no.2, pp.358-366, March 2010.

[4] W. Wang, “Spectrum Sensing for Cognitive Radio,” Third International Symposium on Intelligent Information Technology Application Workshops, Nanchang, pp. 410-412, Nov 2009.

[5] J. Mitola and G. Q. Maguire, “Cognitive radio: making software radios more personal,” IEEE Personal Communications, vol. 6, no. 4, pp. 13-18, Aug 1999.

[6] 廖建興, “感知無線電-最新技術發展趨勢概論” IECQ報導年刊, vol. 2, pp. 49-54, 民國101年9月.

[7] S. Haykin, “Cognitive radio: brain-empowered wireless communications,” IEEE Journal on Selected Areas in Communication, vol.23, no.2, pp.201-220, February 2005.

[8] Wei Zhang, R. K. Mallik, and K. Letaief, “Cooperative Spectrum Sensing Optimization in Cognitive Radio Networks,” IEEE International Conference on Communications 2008 (ICC '08), pp. 3411-3415, May 2008.

[9] Federal Communications Commission, “ Spectrum Policy Task Force,” Rep. ET Docket no. 02-135, Nov. 2002.

[10] T. A. Weiss, F. K. Jondral, “Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency,” IEEE Communications Magazine, vol. 42, no. 3, pp. S8-14, Mar 2004.

[11] C.Cox, “An introduction to LTE: LTE, LTE-advanced, SAE and 4G mobile communications,” John Wiley & Sons, pp. 61-76, 2012

[12] T. Weiss, et al. “Mutual interference in OFDM-based spectrum pooling systems,” Vehicular Technology Conference, VTC 2004-Spring. 2004 IEEE 59th. Vol. 4, 2004.

[13] T. A. Weiss, F. K. Jondral, “Spectrum pooling: an innovative strategy for the enhancement of spectrum efficiency,” IEEE Communications Magazine, vol. 42, no. 3, pp. S8-14, Mar 2004.

[14] T. Yucek, and H. Arslan, “A survey of spectrum sensing algorithms for cognitive radio applications,” IEEE Communications Surveys & Tutorials, vol. 11, no. 1, pp. 116-130, March 2009.

[15] L. Akyildiz, Brandon F. Lo, “CRAHNs: Cognitive radio ad hoc networks,” Physical Communication, vol.7, no.5, pp.810-836, July 2009.

[16] L. Akyildiz, Brandon F. Lo, “Cooperative spectrum sensing in cognitive radio networks: A survey,” Physical Communication, vol.4, no.1, pp.40-62, March 2011.

[17] S. Atapattu, C. Tellambura, and H. Jiang. “Energy detection based cooperative spectrum sensing in cognitive radio networks,” IEEE Transactions on wireless communications, vol. 10, no. 4, pp. 1232-1241, April 2011.

[18] D. Cabric, S. M. Mishra and R. W. Brodersen, “Implementation issues in spectrum sensing for cognitive radios,” Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, vol. 1, pp. 772-776, 2004.

[19] 陳尹宗, “多天線能量偵測器於瑞雷衰弱通道之合作式最佳化” 國立東華大學電機工程研究所碩士論文, 民國106年7月.

[20] W. Zhang, R. K. Mallik and K. B. Letaief, “Optimization of cooperative spectrum sensing with energy detection in cognitive radio networks,” IEEE Transactions on Wireless Communications, vol. 8, no. 12, pp. 5761-5766, December 2009.

[21] Atapattu, Saman, Chintha Tellambura, and Hai Jiang. “Energy detection for spectrum sensing in cognitive radio,” New York, NY, USA, Springer, pp. 63-83, 2014.

[22] A. Shahzad et al., “Comparative Analysis of Primary Transmitter Detection Based Spectrum Sensing Techniques in Cognitive Radio Systems,” Australian Journal of Basic and Applied Sciences vol. 4, no. 9, pp. 4522-4531, September 2010.

[23] 劉陶慶, “基於多天線能量偵測器之合作式頻譜偵測決策融合及最佳化於感知無線電,” 國立東華大學電機工程研究所碩士論文, 民國105年7月.

[24] 林品榮, “使用干擾對齊於行動通道下受到都普勒效應的MIMO系統效能分析,” 國立東華大學電機工程研究所碩士論文, 民國103年7月.

[25] P. Kyosti, et al., “WINNER II channel models,” European Commission, IST-4-027756-WINNER, Tech. Rep. D1.1.2, Sep 2007.