【正文】 =????????????NKKNk FFFKN1 121 ))()(()( ??? = 02)( ?? ?NF (17) 12)( ?? ??GPB (18) 則： ))(1)(1( 020 ??? ???? Nf FQ (19) 黃石理工學院 畢業(yè)設(shè)計（論文）外文文獻翻譯 ))(1)(1( 121 ??? ???? Nf GQ (20) 由上式可知當 0? =0 時，此算法與常規(guī)算法相同。當參與協(xié)同的認知用戶數(shù)目N 較大時， 00?? ，則基于雙門限的頻譜檢測算法的檢測性能與常規(guī)能量算法的檢測性能近似，可知在控制信道帶寬受限制的情況下以較小的性能損失大大降低了網(wǎng)絡(luò)開銷。 4 仿真及分析 本節(jié)通過計算機仿真來評估所提出的基于信任度的雙門限協(xié)同頻譜感知算法的性能。仿真參數(shù)設(shè)置如表 1 所示。 表 1 仿真參數(shù)設(shè)置 參數(shù) 數(shù)值 認知用戶數(shù)目 10?N 平均信噪比 db10_ ?? 時間帶寬積 5?m 授權(quán)用戶占用信道概率 ?op 授權(quán)用戶不占用信道概率 ?p 圖 3 給出了在 ?? 的情況下算法的檢測性能。 可以看出同常規(guī)能量檢測算法相比較，本文所提出算法 的檢測性能得到了明顯的改善。例如當 ?fQ 時，基于信任度的雙門限協(xié)同頻譜感知算法的檢測概率 dQ 比常規(guī)能量檢測算法高出。 黃石理工學院 畢業(yè)設(shè)計（論文）外文文獻翻譯 圖 3檢測性能示意圖 圖 4 描述了 在不同 0? 的條件下，基于信任度的雙門限協(xié)同頻譜感知算法對網(wǎng)絡(luò)開銷的影響。同常規(guī)能量檢測算法即 0? =0 時相比較，本文所提出算法的歸一化平均感知位數(shù) avgK 急劇下降，控制信道帶寬與認知用戶數(shù)量之間的矛盾得到了緩解。例如當 ?fQ ， 0? = 時，基于信任度的雙門限協(xié)同頻譜感知算法的歸一化平均感知位數(shù) avgK 下降了 38%。當 ?fQ ， 0? = 時，歸一化平均感知位數(shù) avgK則下降了 44% 圖 4 不同 0? 條件下算法對網(wǎng)絡(luò)開銷的影響 黃石理工學院 畢業(yè)設(shè)計（論文）外文文獻翻譯 5 結(jié)束語 頻譜感知技術(shù)是認知無線電網(wǎng)絡(luò)的支撐技術(shù)之一。當認知用戶數(shù)量很大的時候，控制信道的帶寬將不夠用。本文提出了認知無線電環(huán)境下一種基于信任度的雙門限協(xié)同頻譜感知算法。每個認知用戶基于雙檢測門限獨立進行頻譜感知，但只有部分可靠的認知用戶通過控制信道向認知無線網(wǎng)絡(luò)基站發(fā)射感知報告。當所有的用戶都不可靠時，選取信任度最高的認知用戶發(fā)射感知報告進行判決。本文對該算法進行了性能分析并通過仿真表明，本文方法比較常規(guī) 能量檢測算法， 在 減小網(wǎng)絡(luò)開銷的同時提高了檢測性能。 參考文獻 [1] Federal Communications Commission. Spectrum Policy Task Force, Rep. ET Docket no. 02135 [R]. Nov. 2020. [2] J. Mitola and G. Q. Maguire. Cognitive radio: Making software radios more personal[C],IEEE Personal Communication. vol. 6, pp. 13–18, Aug. 1999. [3] S. Haykin. Cognitive radio: brainempowered wireless munications [J]. IEEE J. Sel. Areas Communication. vol. 23, pp. 201–220, Feb. 2020. [4] AKYLDIZ IF. Next generation/dynamic spectrum access/cognitive radio wireless works: A Survey [J]. ELSEVIER Computer Networks, 2020(50):21272159. [5] D. Cabric, S. M. Mishra, and R. W. Brodersen. Implementation issues in spectrum sensing for cognitive radios[C]// in Proc. Of A silomar Conf. on Signals, Systems, and Computers, Pacific Grove,CA, USA, Nov. 710, 2020, pp. 772 776. [6] and E. S. Sousa. Collaborative spectrum sensing for opportunistic access in fading environments[C]// in Proc. 1st IEEES ymp. New Frontiers in Dynamic Spectrum Access Networks, Baltimore, USA, Nov. 8–11, 2020, pp. 131–136. [7] Chunhua Sun, Wei Zhang, Letaief . Cooperative spectrum sensing for cognitive radios under bandwidth constraints[C]// in Proc. IEEE WCNC, March 1115, 2020, pp. 15. [8] H. Urkowitz. Energy detection of unknown deterministic signals [C]. Proceedings of IEEE, , pp. 523531, April 1967. [9] Ruiliang Chen, JungMin Park, Kaigui Bian. Robust Distributed Spectrum Sensing in Cognitive 黃石理工學院 畢業(yè)設(shè)計（論文）外文文獻翻譯 Radio Networks[C]. in Proc. IEEEINFOCOM, April 2020, pp. 18761884. [10] F. F. Digham, M. S. Alouini, and M. K. Simon. On the energy detection of unknown signals over fading channels[C]. in Proc. IEEE ICC, Anchorage, AK, USA, May 1115, 2020, pp. 3575–3579. 黃石理工學院 畢業(yè)設(shè)計（論文）外文文獻翻譯 附原文： A New Cooperative Spectrum Sensing Algorithm for Cognitive Radio Networks Abstract—spectrum sensing is a critical phase in building a cognitive radio work. However, the bandwidth for reporting secondary users’ sensing results will be insufficient, when the number of secondary user is very large. In this paper, we propose a new cooperative spectrum sensing algorithm to alleviate the bandwidth problem of reporting channel. Compared with conventional method, only the secondary users with reliable information are allowed to report their sensing results. When no user with reliable information, only the secondary user with highest reputation will report its sensing result. Simulation results show that our algorithm achieves better sensing performance and the average number of sensing bits decrease greatly. Keywords— cognitive radio。 cooperative spectrum sensing。 double threshold。 reputation Ⅰ . INTRODUCTION Due to the increasingly development of wireless applications, more and more spectrum resources are needed to support numerous emerging wireless service. However, recent measurements by Federal Communication Commission (FCC) have shown that 70% of the allocated spec