基于中继传输的协作频谱感知方案研究
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摘要
随着无线通信的迅速发展,对频谱资源的需求越来越旺盛,认知无线电技术是解决频谱资源稀缺的有效的技术。频谱感知是认知无线电的核心技术,能够及时地检测到可用的频谱,同时避免对授权用户的干扰。协作频谱感知技术是多个认知用户协作工作,相比较单用户频谱感知技术,可以更加稳定可靠地提供感知信息,降低系统的虚警概率和漏检概率,成为近几年频谱感知技术的研究热点。
当认知用户与融合判决中心之间的信道存在障碍物遮挡时,传统的协作频谱感知方案由于一部分感知信息的丢失,导致系统可靠性将会大大地降低。本文针对上述问题,在总结了现有的各种频谱感知方法的基础上,研究了基于中继传输的协作频谱感知方案。该方案结合正交频分复用、线性复数域编码以及循环延迟技术,把协作频谱感知和协作中继传输有机地结合起来,很好地解决了认知用户与融合判决中心之间存在障碍物遮挡时多用户信息丢失的问题,具有一定的实际应用和理论研究的价值。论文的主要研究工作如下：
首先,本文研究了频谱感知的本地检测算法及优缺点,针对单用户检测的局限性,引入了多用户协作频谱检测的概念,并详细研究了融合判决准则。随后本文简单地介绍了中继传输的一些简单模型,并且在传统的单链路的基础上,着重研究了双链路两跳传输模型,为论文的核心部分奠定理论基础。
其次,在以上研究的基础上,本文重点研究了存在遮挡的多用户协作频谱感知方案,构造了存在遮挡的多用户协作频谱感知模型,整个协作频谱感知的过程共分为四个时隙来完成。在第一个时隙内,每个认知用户进行独立地进行频谱感知,得到最初的感知信息；在后三个时隙内,结合中继传输技术,认知用户把自己的感知信息发送给融合中心做最终的融合判决。在该方案中,通过对每个认知用户的感知信息进行编码传输来获得系统的分集增益,同时多次采用循环延迟技术,提高系统的检测性能,降低系统检测的复杂度。
最后通过仿真分析证明了本文研究的方案在一定程度上避免了感知信息的丢失,可以有效地降低虚警概率和漏检概率,提高系统的感知性能。
With the rapid development of wireless communication technology, the demand for spectrum resources is strong increasingly. Cognitive radio arises to be an important solution to the spectrum scarcity problem by finding spectrum space holes. Spectrum sensing is one of the most important constituents for the establishment of cognitive radio networks which could identify the available spectrum and prevent the harmful interference with licensed users. Ensuring cooperation among secondary users could gain improved detection performance, reduce the probability of false alarm and missed detection probability, some experts focus on the cooperative spectrum sensing technique.
In the system of cooperative spectrum sensing, if the channel between cognitive user and the fusion decision center exists stumbling block, the reliability of cooperative spectrum sensing will be reduced greatly, the case can cause the loss of some sensing information.To reduce the probability of false alarm and missed probability, the scheme is discussed about cooperative spectrum sensing based on cooperative relay transmission. Combination of orthogonal frequency division multiplexing, pre-coding and cyclic delay diversity techniques, cooperative spectrum sensing and cooperative relay transmission are fully considered and properly combined to solve the problem about the loss of sensing information. The main research work are as follows.
In this thesis, algorithms of local detection are discussed. Due to the limitation of local detection, cooperative spectrum sensing is studied to improve the detection performance and fusion rules are summed up. And then, some simple model of relay transmission are discussed. A cooperative communication network is proposed, this is the theoretical foundation for the core part of the thesis.
The thesis is discussed about cooperative spectrum sensing, when the channels exist stumbling block. The model about cooperative spectrum sensing is conducted. The entire cooperative spectrum sensing process is divided into four time slots to complete. In the first slot, each cognitive user independently detected, within the rest of the three slots, combined the relay transmission technology, cognitive user send the information to the fusion center to do the finally judgment. In this scheme, frequency diversity gain is achieved through coded transmission, while the cyclic delay technology is used repeatedly to improve the detection performance, and reduce the detection complexity.
Simulation results show that the proposed scheme can improve the system performance,reduce the probability of false alarm and missed probability.
当认知用户与融合判决中心之间的信道存在障碍物遮挡时,传统的协作频谱感知方案由于一部分感知信息的丢失,导致系统可靠性将会大大地降低。本文针对上述问题,在总结了现有的各种频谱感知方法的基础上,研究了基于中继传输的协作频谱感知方案。该方案结合正交频分复用、线性复数域编码以及循环延迟技术,把协作频谱感知和协作中继传输有机地结合起来,很好地解决了认知用户与融合判决中心之间存在障碍物遮挡时多用户信息丢失的问题,具有一定的实际应用和理论研究的价值。论文的主要研究工作如下：
首先,本文研究了频谱感知的本地检测算法及优缺点,针对单用户检测的局限性,引入了多用户协作频谱检测的概念,并详细研究了融合判决准则。随后本文简单地介绍了中继传输的一些简单模型,并且在传统的单链路的基础上,着重研究了双链路两跳传输模型,为论文的核心部分奠定理论基础。
其次,在以上研究的基础上,本文重点研究了存在遮挡的多用户协作频谱感知方案,构造了存在遮挡的多用户协作频谱感知模型,整个协作频谱感知的过程共分为四个时隙来完成。在第一个时隙内,每个认知用户进行独立地进行频谱感知,得到最初的感知信息；在后三个时隙内,结合中继传输技术,认知用户把自己的感知信息发送给融合中心做最终的融合判决。在该方案中,通过对每个认知用户的感知信息进行编码传输来获得系统的分集增益,同时多次采用循环延迟技术,提高系统的检测性能,降低系统检测的复杂度。
最后通过仿真分析证明了本文研究的方案在一定程度上避免了感知信息的丢失,可以有效地降低虚警概率和漏检概率,提高系统的感知性能。
With the rapid development of wireless communication technology, the demand for spectrum resources is strong increasingly. Cognitive radio arises to be an important solution to the spectrum scarcity problem by finding spectrum space holes. Spectrum sensing is one of the most important constituents for the establishment of cognitive radio networks which could identify the available spectrum and prevent the harmful interference with licensed users. Ensuring cooperation among secondary users could gain improved detection performance, reduce the probability of false alarm and missed detection probability, some experts focus on the cooperative spectrum sensing technique.
In the system of cooperative spectrum sensing, if the channel between cognitive user and the fusion decision center exists stumbling block, the reliability of cooperative spectrum sensing will be reduced greatly, the case can cause the loss of some sensing information.To reduce the probability of false alarm and missed probability, the scheme is discussed about cooperative spectrum sensing based on cooperative relay transmission. Combination of orthogonal frequency division multiplexing, pre-coding and cyclic delay diversity techniques, cooperative spectrum sensing and cooperative relay transmission are fully considered and properly combined to solve the problem about the loss of sensing information. The main research work are as follows.
In this thesis, algorithms of local detection are discussed. Due to the limitation of local detection, cooperative spectrum sensing is studied to improve the detection performance and fusion rules are summed up. And then, some simple model of relay transmission are discussed. A cooperative communication network is proposed, this is the theoretical foundation for the core part of the thesis.
The thesis is discussed about cooperative spectrum sensing, when the channels exist stumbling block. The model about cooperative spectrum sensing is conducted. The entire cooperative spectrum sensing process is divided into four time slots to complete. In the first slot, each cognitive user independently detected, within the rest of the three slots, combined the relay transmission technology, cognitive user send the information to the fusion center to do the finally judgment. In this scheme, frequency diversity gain is achieved through coded transmission, while the cyclic delay technology is used repeatedly to improve the detection performance, and reduce the detection complexity.
Simulation results show that the proposed scheme can improve the system performance,reduce the probability of false alarm and missed probability.
引文
[1]Ganesan G, Li Y. Agility improvement through cooperative diversity in cognitive radio networks [C].Missouri, USA:GLOBECOM 2005,2005, Vol.5:5pp.
[2]Wang B., Liu K. J. R., "Advances in cognitive radio networks:a survey"[J], IEEE Journal of Selected Topics in Signal Processing,2011,5(1):5-23.
[3]Amanna A., Reed J. H., "Survey of cognitive radio architectures"[J], in proceedings of the IEEE Southeast Conference (SEC-2010):292-297.
[4]Chen Q., Motani M., Wong W., Nallanathan A., "Cooperative spectrum sensing strategies for cognitive radio mesh networks"[J], IEEE Journal of Selected Topics in Signal Processing, 2011,5(1):56-67.
[5]Kim S., Dall'Anese E., Giannakis G. B., "Cooperative spectrum sensing for cognitive radios using Kriged Kalman filtering"[J], IEEE Journal of Selected Topics in Signal Processing, 2011,5(1):24-36.
[6]Michalopoulos D. S., Lioumpas A. S., Karagiannidis G. K., Schober R., "Selective cooperative relaying over time-varying channels"[J], IEEE Transactions on Communications, 2010,58(8):2402-2412.
[7]Kandeepan S., Rahim A. B., Aysal T. C., Piesiewicz R., "Time divisional and time- frequency divisional cooperative spectrum sensing"[J], in proceedings of the 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communication (CrownCom-2009):1-6.
[8]Sun C., Zhang W., Ben K., "Cluster-based cooperative spectrum sensing in cognitive radio systems"[J], in proceedings of IEEE International Conference on Communications (IEEE ICC-2007):2511-2515.
[9]Zeng K., Paweczak P., Cabric D., "Reputation-based cooperative spectrum sensing with trusted nodes assistance"[J], IEEE Communications Letters,2010,14(3):226-228.
[10]Li G., Cano A., Zhu S., "High-diversity cooperative spectrum sensing in cognitive radio networks"[J], in proceedings of the IEEE Global Telecommunications Conference (IEEE GLOBECOM-2010):1-5.
[11]Duan D., Yang L., Principe J. C., "Cooperative diversity of spectrum sensing for cognitive radio systems"[J], IEEE Transactions on Signal Processing,2010,58(6):3218-3227.
[12]Shi-Qi Liu, Bin-Jie Hu, Xian-Yi Wang, "Hierarchical cooperative spectrum sensing based on double thresholds energy detection"[J], in Proc 2012 IEEE Vehicular Technology Conference, vols,pp.519-523.
[13]Shiwei Huang, Hongbin Chen, Yan Zhang, Feng Zhao, "Energy-efficient cooperative spectrum sensing with amplify and forward relaying"[J], IEEE Communications letters, vol.16, No.4,April 2012,450-453.
[14]S. Atapattu, C. Tellambura, and H. Jiang, "Energy detection based cooperative spectrum sensing in cognitive radio networks"[J], IEEE Trans.Wireless, vol.10, no.4, pp.1232-1241, Apr.2011.
[15]Ruilong Deng, Jiming Chen, Chau Yuen, Peng Cheng, Youxian Sun, "Energy Efficient cooperative spectrum sensing by optimal scheduling in sensor-aided cognitive radio networks"[J], IEEE Trans.on vehicular technology,2012,716-725.
[16]Ma X., Giannakis G. B., "Full-diversity full-rate complex-field space-time coding"[J], IEEE Transactions on Signal Processing,2003,51(11):2917-2930.
[17]张红伟,“宽带移动通信系统中空时频编码关键技术的研究”[M],上海交通大学博士论文,2006年。
[18]Kwon U., Choi C., Im G., "Full-rate cooperative communications with spatial diversity for half-duplex uplink relay channels"[J], IEEE Transactions on Wireless Communications, 2009,8(11):5449-5454.
[19]Wang H., Yin Q., Xia X., "Full diversity space-frequency codes for frequency asynchronous cooperative relay networks with linear receivers"[J], IEEE Transactions on Communications,2011,59(1):236-247.
[20]Zhang H., Li X., Lu L.(张红伟,李晓辉,陆璐),"Rate-embedded doubly directional differential space-time-frequency coding schemes"[J], in proceedings of the 5th International Conference on Wireless Communications Networking and Mobile Computing (WiCOM-2009):1-4.
[21]Yuan J., Li Y., Chu L., "Differential modulation and relay selection with detect-and-forward cooperative relaying"[J], IEEE Transactions on Vehicular Technology,2010,59(1): 261-268.
[22]马志垚,曹志刚,“认知无线电网络用户合作机会接入方案的研究”[J],电子学报,2009, 37(4)：678-683。
[23]甘小莺,徐昊,徐友云,钱良,刘静,“认知无线电系统中有限长度循环谱检测的噪声特性分析”[J],解放军理工大学学报,2008,9(9)：633-636。
[24]Ma W., Hu S., Wang Y., Zhu L., "Cooperative Spectrum Sensing in OFDM Based on MIMO Cognitive Radio Sensor Networks"[J], in Proceedings of the 5th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM-2009):1-4.
[25]岳文静,郑宝玉,孟庆民,崔景伍,解培中,“衰落信道下提高协作频谱感知能力的方法”[J]2011,41(2)：207-218。
[26]Zou Y., Yao Y, Zheng B., "A cooperative sensing based cognitive relay transmission scheme without a dedicated sensing relay channel in cognitive radio networks"[J], IEEE Transactions on Signal Processing,2011,59(2):854-858.
[27]崔丽,王金龙,吴启晖,郑学强,“认知无线电中基于信息简约的最大似然协同频谱感知算法”[J],电子与信息学报,2009,31(9)：2177-2182。
[28]夏文芳,王殊,龚世民,刘威,“协作频谱感知中快速自适应门限策略’’[J],电子与信息学报,2010,32(6)：1406-1411。
[29]王谦,岳殿武,“分集技术下频谱感知的性能分析”[J]通信学报,2010,134-140。
[30]Akyildiz Ian F., Lee Won-yeol, Vuran Mehmet C., Mohanty Shantidev. Next generation/ dynamic spectrum access/cognitive radio wireless networks:A survey[J]. Computer Networks.2006,50(13):2127-2159.
[31]Tang H. Some physical layer issues of wide-band cognitive radio system[C]. New Frontiers in Dynamic Spectrum Access Networks,2005. DySPAN 2005.2005 First IEEE International Symposium on,2005:151-159.
[32]Cabric D., Tkachenko A., Brodersen R. W. Spectrum Sensing Measurements of Pilot, Energy, and Collaborative Detection[C]. Military Communications Conference,2006:1-7.
[33]Cabric D., Brodersen R. W. Physical layer design issues unique to cognitive radio systems[C]. Personal, Indoor and Mobile Radio Communications,2005. PIMRC2005. IEEE 16th International Symposium on,2005:759-763.
[34]Digham F. F., Alouini M. K. On the energy detection of unknown signals over fading channels[C]. Communications,2003. ICC'03.IEEE International Conference on,2003:21-24.
[35]张宇,冯春燕,郭彩丽,曾志民.认知无线电网络频谱检测研究[J].吉林大学学报(信息科学版).2008,26(2)：126-135.
[36]Chen Yunfei. Optimum number of secondary users in collaborative spectrum sensing considering resources usage efficiency [J].IEEE Communications Letters,2008,12(12): 877-879.
[38]Zhang wei, Mallik R K, Ben Letaief K. Cooperative spectrum sensing optimization in cognitive radio networks[C]. Proceedings of 2008 IEEE International Conference On Communications, New York:IEEE,2008,3,411-3415.
[39]林威,吴捷,张饮宇.基于认知无线电系统合作检测的数据融合研究[J].通信学报,Oct,2009,vol.30, No.10,135-140.
[40]覃琴,曾志民,郭彩丽.协作频谱感知中数据融合与决策算法比较[J].电讯技术,Jul,2009,Vol.49, No.7,5-8.
[41]卞荔,朱琦.基与数据融合的频谱感知算法[J].南京邮电大学学报(自然科学版),Apr,2009,Vol.29, No.2,73-78.
[42]彭霄,吴素文,朱近康.一种高效利用资源的协作感知方法[J].中国科学技术大学学报,Oct,2009, vol.39, No.10,1039-1044.
[43]王磊,郑宝玉,李磊.基于随机矩阵理论的协作频谱感知[J].电子信息学报,Aug.2009, Vol.31,No.8,1925-1929.
[2]Wang B., Liu K. J. R., "Advances in cognitive radio networks:a survey"[J], IEEE Journal of Selected Topics in Signal Processing,2011,5(1):5-23.
[3]Amanna A., Reed J. H., "Survey of cognitive radio architectures"[J], in proceedings of the IEEE Southeast Conference (SEC-2010):292-297.
[4]Chen Q., Motani M., Wong W., Nallanathan A., "Cooperative spectrum sensing strategies for cognitive radio mesh networks"[J], IEEE Journal of Selected Topics in Signal Processing, 2011,5(1):56-67.
[5]Kim S., Dall'Anese E., Giannakis G. B., "Cooperative spectrum sensing for cognitive radios using Kriged Kalman filtering"[J], IEEE Journal of Selected Topics in Signal Processing, 2011,5(1):24-36.
[6]Michalopoulos D. S., Lioumpas A. S., Karagiannidis G. K., Schober R., "Selective cooperative relaying over time-varying channels"[J], IEEE Transactions on Communications, 2010,58(8):2402-2412.
[7]Kandeepan S., Rahim A. B., Aysal T. C., Piesiewicz R., "Time divisional and time- frequency divisional cooperative spectrum sensing"[J], in proceedings of the 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communication (CrownCom-2009):1-6.
[8]Sun C., Zhang W., Ben K., "Cluster-based cooperative spectrum sensing in cognitive radio systems"[J], in proceedings of IEEE International Conference on Communications (IEEE ICC-2007):2511-2515.
[9]Zeng K., Paweczak P., Cabric D., "Reputation-based cooperative spectrum sensing with trusted nodes assistance"[J], IEEE Communications Letters,2010,14(3):226-228.
[10]Li G., Cano A., Zhu S., "High-diversity cooperative spectrum sensing in cognitive radio networks"[J], in proceedings of the IEEE Global Telecommunications Conference (IEEE GLOBECOM-2010):1-5.
[11]Duan D., Yang L., Principe J. C., "Cooperative diversity of spectrum sensing for cognitive radio systems"[J], IEEE Transactions on Signal Processing,2010,58(6):3218-3227.
[12]Shi-Qi Liu, Bin-Jie Hu, Xian-Yi Wang, "Hierarchical cooperative spectrum sensing based on double thresholds energy detection"[J], in Proc 2012 IEEE Vehicular Technology Conference, vols,pp.519-523.
[13]Shiwei Huang, Hongbin Chen, Yan Zhang, Feng Zhao, "Energy-efficient cooperative spectrum sensing with amplify and forward relaying"[J], IEEE Communications letters, vol.16, No.4,April 2012,450-453.
[14]S. Atapattu, C. Tellambura, and H. Jiang, "Energy detection based cooperative spectrum sensing in cognitive radio networks"[J], IEEE Trans.Wireless, vol.10, no.4, pp.1232-1241, Apr.2011.
[15]Ruilong Deng, Jiming Chen, Chau Yuen, Peng Cheng, Youxian Sun, "Energy Efficient cooperative spectrum sensing by optimal scheduling in sensor-aided cognitive radio networks"[J], IEEE Trans.on vehicular technology,2012,716-725.
[16]Ma X., Giannakis G. B., "Full-diversity full-rate complex-field space-time coding"[J], IEEE Transactions on Signal Processing,2003,51(11):2917-2930.
[17]张红伟,“宽带移动通信系统中空时频编码关键技术的研究”[M],上海交通大学博士论文,2006年。
[18]Kwon U., Choi C., Im G., "Full-rate cooperative communications with spatial diversity for half-duplex uplink relay channels"[J], IEEE Transactions on Wireless Communications, 2009,8(11):5449-5454.
[19]Wang H., Yin Q., Xia X., "Full diversity space-frequency codes for frequency asynchronous cooperative relay networks with linear receivers"[J], IEEE Transactions on Communications,2011,59(1):236-247.
[20]Zhang H., Li X., Lu L.(张红伟,李晓辉,陆璐),"Rate-embedded doubly directional differential space-time-frequency coding schemes"[J], in proceedings of the 5th International Conference on Wireless Communications Networking and Mobile Computing (WiCOM-2009):1-4.
[21]Yuan J., Li Y., Chu L., "Differential modulation and relay selection with detect-and-forward cooperative relaying"[J], IEEE Transactions on Vehicular Technology,2010,59(1): 261-268.
[22]马志垚,曹志刚,“认知无线电网络用户合作机会接入方案的研究”[J],电子学报,2009, 37(4)：678-683。
[23]甘小莺,徐昊,徐友云,钱良,刘静,“认知无线电系统中有限长度循环谱检测的噪声特性分析”[J],解放军理工大学学报,2008,9(9)：633-636。
[24]Ma W., Hu S., Wang Y., Zhu L., "Cooperative Spectrum Sensing in OFDM Based on MIMO Cognitive Radio Sensor Networks"[J], in Proceedings of the 5th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM-2009):1-4.
[25]岳文静,郑宝玉,孟庆民,崔景伍,解培中,“衰落信道下提高协作频谱感知能力的方法”[J]2011,41(2)：207-218。
[26]Zou Y., Yao Y, Zheng B., "A cooperative sensing based cognitive relay transmission scheme without a dedicated sensing relay channel in cognitive radio networks"[J], IEEE Transactions on Signal Processing,2011,59(2):854-858.
[27]崔丽,王金龙,吴启晖,郑学强,“认知无线电中基于信息简约的最大似然协同频谱感知算法”[J],电子与信息学报,2009,31(9)：2177-2182。
[28]夏文芳,王殊,龚世民,刘威,“协作频谱感知中快速自适应门限策略’’[J],电子与信息学报,2010,32(6)：1406-1411。
[29]王谦,岳殿武,“分集技术下频谱感知的性能分析”[J]通信学报,2010,134-140。
[30]Akyildiz Ian F., Lee Won-yeol, Vuran Mehmet C., Mohanty Shantidev. Next generation/ dynamic spectrum access/cognitive radio wireless networks:A survey[J]. Computer Networks.2006,50(13):2127-2159.
[31]Tang H. Some physical layer issues of wide-band cognitive radio system[C]. New Frontiers in Dynamic Spectrum Access Networks,2005. DySPAN 2005.2005 First IEEE International Symposium on,2005:151-159.
[32]Cabric D., Tkachenko A., Brodersen R. W. Spectrum Sensing Measurements of Pilot, Energy, and Collaborative Detection[C]. Military Communications Conference,2006:1-7.
[33]Cabric D., Brodersen R. W. Physical layer design issues unique to cognitive radio systems[C]. Personal, Indoor and Mobile Radio Communications,2005. PIMRC2005. IEEE 16th International Symposium on,2005:759-763.
[34]Digham F. F., Alouini M. K. On the energy detection of unknown signals over fading channels[C]. Communications,2003. ICC'03.IEEE International Conference on,2003:21-24.
[35]张宇,冯春燕,郭彩丽,曾志民.认知无线电网络频谱检测研究[J].吉林大学学报(信息科学版).2008,26(2)：126-135.
[36]Chen Yunfei. Optimum number of secondary users in collaborative spectrum sensing considering resources usage efficiency [J].IEEE Communications Letters,2008,12(12): 877-879.
[38]Zhang wei, Mallik R K, Ben Letaief K. Cooperative spectrum sensing optimization in cognitive radio networks[C]. Proceedings of 2008 IEEE International Conference On Communications, New York:IEEE,2008,3,411-3415.
[39]林威,吴捷,张饮宇.基于认知无线电系统合作检测的数据融合研究[J].通信学报,Oct,2009,vol.30, No.10,135-140.
[40]覃琴,曾志民,郭彩丽.协作频谱感知中数据融合与决策算法比较[J].电讯技术,Jul,2009,Vol.49, No.7,5-8.
[41]卞荔,朱琦.基与数据融合的频谱感知算法[J].南京邮电大学学报(自然科学版),Apr,2009,Vol.29, No.2,73-78.
[42]彭霄,吴素文,朱近康.一种高效利用资源的协作感知方法[J].中国科学技术大学学报,Oct,2009, vol.39, No.10,1039-1044.
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