认知协作场景下的中继选择策略研究
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摘要
纵观移动通信系统的发展历史可以发现,不断满足人们对于无线数据业务的需求是无线通信系统领域的一个永恒主题。随着先进移动通信技术的不断涌现,频谱资源紧张问题变得日益严重。然而,研究发现目前的固定频谱分配政策存在着频谱利用程度极度不平衡的现象：一些频谱在大部分时间里被闲置不用,另一些频谱资源却过于拥挤。在这样的背景下,认知无线电技术应运而生。它能够感知周围复杂的无线环境,发现处于空闲的频谱资源,并且通过动态地改变自身参数,以实现对频谱资源的再次利用。目前,认知无线电技术被认为是最有发展前景的无线通信技术。
在认知无线电网络中,主从系统共存于同一地理区域,从系统一方而需要注意避免对主系统产生有害干扰,另一方面也需要保证从用户的通信质量。将中继通信技术引入认知无线电从系统之中,通过中继的协作：首先可以利用信道的独立性来提高频谱检测的准确率,避免对主系统的干扰；其次可以利用中继节点的频谱资源进行数据的传输,提高频谱利用率,保证从用户的通信质量。因此,认知无线电网络中的中继选择问题成为一个研究热点。
本文研究的是如何选取合适的中继进行数据转发。通过研究发现,已有的随机中继选择方案算法仅仅考虑对主用户的干扰,算法复杂度低、易于实现,但是所选中继的信道条件很有可能无法满足源端数据传输速率需求,造成从用户通信中断。最佳信道条件中继选择方案虽然同时考虑了对主用户的干扰以及无线信道的质量差异,但是忽略了在认知无线电从系统中,中继节点可用频谱资源动态变化的特性。所以,由于地理位置以及主用户活动的影响,中继节点的可用频谱空洞可能不足以完成源节点数据的转发,进而造成从用户通信中断。因此,本文通过分析主用户活动对从系统中继节点可用频谱资源的影响以及不同传输链路之间的无线信道质量,提出了联合考虑信道质量与中继节点可用资源的中继选择算法。理论分析与计算机仿真均表明该策略能大幅提高系统的吞吐量,减少用户通信中断,保证用户通信质量,极大地改善了系统性能。
It can be found from the development of mobile communication system that it is an eternal theme in the field of wireless communication to meet people's increasing need of wireless data service. With the advanced mobile communication technologies continuing to emerge, the shortage of spectrum resources is becoming increasingly serious. However, the current fixed spectrum allocation policy exists extreme imbalance in spectrum utilization: some spectrum resource is idle most of time, while others may be overcrowded. Cognitive radio emerged in this situation. This technology can sense the wireless environment, and find the idle spectrum resource, and then chance transmission parameters dynamically, which aimed at re-using the spectrum resource. Now, cognitive radio is regarded as the most promising technology of wireless communication.
In cognitive radio network, the primary system co-exists with secondary system in the same area. On one hand, the secondary system should avoid interfering the primary system, on the other hand, the secondary system also need to guarantee the quality of secondary users' communication. Due to these reasons, introducing the relay communication into cognitive radio secondary system can firstly improve the performance of spectrum detection by utilizing the independence of wireless channels and secondly improve spectrum utilization by forwarding the data. Hence, the relay selection has become the hot topic in cognitive radio network.
This paper researches on relay selection in the scene of cooperation cognitive radio network aiming at improving the quality of service for secondary user. It finds that random relay selection scheme only consider the interference to primary user with low complexity. However the selected relay may not match the needed data rate of transmitter, and thus lead to communication outage. The best SNR relay selection scheme considers both interference to primary user and quality of wireless, but it ignores the characteristic of dynamic changes for the available spectrum holes in the selected relay. Therefore, the location of relay and the activities of primary users may affect the number of available spectrum holes which used to forward resource data, and then result in outage of secondary users. So, this paper studies both the affection of primary activities and the quality of different wireless channels, and propose the combined quality of channel and spectrum resource relay selection scheme. Both theory analysis and computer simulation show that the proposed relay selection scheme can improve the throughput of secondary system, decrease the outage of secondary user, and guarantee the quality of user's communication.
在认知无线电网络中,主从系统共存于同一地理区域,从系统一方而需要注意避免对主系统产生有害干扰,另一方面也需要保证从用户的通信质量。将中继通信技术引入认知无线电从系统之中,通过中继的协作：首先可以利用信道的独立性来提高频谱检测的准确率,避免对主系统的干扰；其次可以利用中继节点的频谱资源进行数据的传输,提高频谱利用率,保证从用户的通信质量。因此,认知无线电网络中的中继选择问题成为一个研究热点。
本文研究的是如何选取合适的中继进行数据转发。通过研究发现,已有的随机中继选择方案算法仅仅考虑对主用户的干扰,算法复杂度低、易于实现,但是所选中继的信道条件很有可能无法满足源端数据传输速率需求,造成从用户通信中断。最佳信道条件中继选择方案虽然同时考虑了对主用户的干扰以及无线信道的质量差异,但是忽略了在认知无线电从系统中,中继节点可用频谱资源动态变化的特性。所以,由于地理位置以及主用户活动的影响,中继节点的可用频谱空洞可能不足以完成源节点数据的转发,进而造成从用户通信中断。因此,本文通过分析主用户活动对从系统中继节点可用频谱资源的影响以及不同传输链路之间的无线信道质量,提出了联合考虑信道质量与中继节点可用资源的中继选择算法。理论分析与计算机仿真均表明该策略能大幅提高系统的吞吐量,减少用户通信中断,保证用户通信质量,极大地改善了系统性能。
It can be found from the development of mobile communication system that it is an eternal theme in the field of wireless communication to meet people's increasing need of wireless data service. With the advanced mobile communication technologies continuing to emerge, the shortage of spectrum resources is becoming increasingly serious. However, the current fixed spectrum allocation policy exists extreme imbalance in spectrum utilization: some spectrum resource is idle most of time, while others may be overcrowded. Cognitive radio emerged in this situation. This technology can sense the wireless environment, and find the idle spectrum resource, and then chance transmission parameters dynamically, which aimed at re-using the spectrum resource. Now, cognitive radio is regarded as the most promising technology of wireless communication.
In cognitive radio network, the primary system co-exists with secondary system in the same area. On one hand, the secondary system should avoid interfering the primary system, on the other hand, the secondary system also need to guarantee the quality of secondary users' communication. Due to these reasons, introducing the relay communication into cognitive radio secondary system can firstly improve the performance of spectrum detection by utilizing the independence of wireless channels and secondly improve spectrum utilization by forwarding the data. Hence, the relay selection has become the hot topic in cognitive radio network.
This paper researches on relay selection in the scene of cooperation cognitive radio network aiming at improving the quality of service for secondary user. It finds that random relay selection scheme only consider the interference to primary user with low complexity. However the selected relay may not match the needed data rate of transmitter, and thus lead to communication outage. The best SNR relay selection scheme considers both interference to primary user and quality of wireless, but it ignores the characteristic of dynamic changes for the available spectrum holes in the selected relay. Therefore, the location of relay and the activities of primary users may affect the number of available spectrum holes which used to forward resource data, and then result in outage of secondary users. So, this paper studies both the affection of primary activities and the quality of different wireless channels, and propose the combined quality of channel and spectrum resource relay selection scheme. Both theory analysis and computer simulation show that the proposed relay selection scheme can improve the throughput of secondary system, decrease the outage of secondary user, and guarantee the quality of user's communication.
引文
[1]沈嘉,索士强,全海洋,等.3GPP长期演进(LTE)技术原理与系统设计[M].北京：人民邮电出版社,2008.425426.
[2]Jakes W.C.. Ed. Microwave Mobile Communications[M]. New York:Wiley,1976.187-188.
[3]FCC. Notice of Proposal rule making and order, ET Docket No 03-222 [R]. USA:FCC,2003.
[4]J.Mitola. G.Q.Maguire. Cognitive Radio:Making software radios more personal[J]. Journal of IEEE of Communication,1999,6(4):13-18.
[5]FCC. Spectrum policy task force report, ET Doeket No.02---155[R]. USA:FCC,2002.
[6]Zou Yulong, Zhu Jia, Zheng Baoyu, et al. An Adaptive Cooperation Diversity Scheme With Best-Relay Selection in Cognitive Radio Networks[J]. IEEE TRANSACTIONS ON SIGNAL PROCESSING,2010,58(10):5438-5445.
[7]Li Liying, Zhou Xiangwei, Xu Hongbing, et al. Simplified Relay Selection and Power Allocation in Cooperative Cognitive Radio Systems[J]. IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS,2011,10(1):33-36.
[8]Si JiangBo, Li Zan, Chen XiaoJun, et al. On the Performance of Cognitive Relay Networks Under Primary User's Outage Constraint[J]. IEEE COMMUNICATIONS LETTERS,2011,15(4): 422-424.
[9]Yulong Zou, Yu-Dong Yao, Baoyu Zheng. Cognitive Transmissions with Multiple Relays in Cognitive Radio Networks[J]. IEEE Transactions on Wireless Communications,2011,10(2): 648-659.
[10]Hsien-Po Shiang, van der Schaar M.. Distributed Resource Management in Multihop Cognitive Radio Networks for Delay-Sensitive Transmission[J]. IEEE Transactions on Vehicular Technology,2009,58(2):941-953.
[11]Ubaidulla P., Aissa, S.. Optimal Relay Selection and Power Allocation for Cognitive Two-Way Relaying Networks[J]. IEEE Transactions on Wireless Communications,2012,1(3):225-228.
[12]Jung-Bin Kim, Dongwoo Kim. Outage Probability and Achievable Diversity Order of Opportunistic Relaying in Cognitive Secondary Radio Networks[J]. IEEE Transactions on Communications,2012,60(9):2456-2466.
[13]刘云学.认知无线电中的频谱感知技术研究[D].山东：山东大学,2009.
[14]Haykin. Cognitive radio:brain-empowered wireless communications[J]. IEEE Journal on Selected Areas in Communications,2005,23(2):201-220.
[15]段志刚.协作通信在认知无线电中的应用研究[D].山东：山东大学,2010.
[16]ABRAMSON N. THE ALOHA SYSTEM:another alternative for computer communications[A]. In:Proceedings of fall joint computer conferencc[C]. New York, US:1970.281-285.
[17]CORDEIRO C, CHALLAPALI K, BIRRU D, et al. the first worldwide wireless standard based on cognitive radios. Baltimore[M]. Maryland:IEEE,2005.328-337.
[18]周小飞,张洪钢.认知无线电原理及应用[M].北京：北京邮电大学出版社,2007.458-461.
[19]Craig Partridge. The XG Vision. V 2.0[HB/OL]. http://www.ir.bbn.com/projects/xmac/vision.html,2012-5-16.
[20]王金龙,吴启辉,龚玉萍,等.认知无线网络[M].北京：机械工业出版社,2010.345-346
[21]Motorola. End-to-End re-configurability, E2R_WP5_D5.3050727[EB/OL]. http://e2r.motlabs.com/Deliverables/H2R_WP5 D5.3050727.pdf,2012-5-16.
[22]Simon Delaere. E3 project [EB/OL]. http://ict-e3.eu/,2012-5-16.
[23]朱江.频谱感知算法及授权用户用频行为研究[D].武汉：华中科技大学,2010.
[24]Senhua H, Zhi D., Xin L. Non-Intrusive Cognitive Radio Networks Based on Smart Antenna Technology[A]. In:Global Telecommunications Conference[C]. IEEE, USA:2007.4862-4867.
[25]Guodong Z., Jun M, Ye L, et al. Spatial Spectrum Holes for Cognitive Radio with Directional Transmission [A]. In:Global Telecommunications Conference [C]. IEEE, USA:2008.1-5.
[26]Karama Hamdi, Khaled Ben Letaief. Power, sensing time, and throughput tradoffs in cognitive radio systems:a cross-layer approach[A]. In:IEEE 2009 Wireless Communications and Networking Conference[C]. IEEE, USA:2009.1-5.
[27]FCC. Notice of Proposed Rule Making and Order, ET Docket No.03-322[R]. USA:FCC,2003.
[28]FCC. Spectrum Policy task force report, ET Docket No.02-155[R]. USA:FCC,2002.
[29]Lin Shufang, Fang Xuming. Two-level Game Based Spectrum Lease Framework in Cognitive Radio Networks[A]. In:Communication Systems[C]. IEEE, USA:2008.104-108.
[30]Wu Yongle, Wang Beibei, Liu K, Clancy T.C.. A Multi-Winner Cognitive Spectrum Auction Framework with Collusion-Resistant Mechanisms[A]. In:New Frontiers in Dynamic Spectrum Access Networks[C]. IEEE, USA:2008.1-9.
[31]Tang Pak Kay, Chew Yong Huat, Ong Ling Chuen, et al. On the Grade-of-Services in the Sharing of Radio Spectrum[A]. In:Cognitive Radio Oriented Wireless Networks and Communications[C]. IEEE, USA:2007.85-89.
[32]Wang Weidong, Wang Ben, Zhang Yinghai, et al. A Novel System Model based on Cost-prediction for Spectrum Leasing in Cognitive Radio[J]. China Communications,2010,7(2):25-26.
[33]Z. Ji, K. Liu. Cognitive radios for dynamic spectrum access-dynamic spectrum sharing:a game theoretical overview[J]. IEEE Communication Magazine,2007,53(8):88-94.
[34]Wang Jiao, Huang Yuqing, Jiang Hong. Improved Algorithm of Spectrum Allocation Based on Graph Coloring Model in Cognitive Radio[A]. In:Comunications and Mobile Computing[C]. USA: 2009.353-357
[35]Anh Tuan Hoang, Ying-Chang Liang. Maximizing Spectrum Utilization of Cognitive Radio Networks Using Channel Allocation and Power Control[A]. In:Vehicular Technology Conference[C]. USA:2006.1-5.
[36]T. Cover, A. El Gamal. Capacity theorems for the relay channel[J]. IEEE Trans. Inform. Theory, 1979,25(3):572-584.
[37]郑侃,彭岳星,龙航,等.协作通信及其在LTE-Advanced中的应用[M].北京：人民邮电出版社,2010.17-18.
[38]B. Vucetic, J. Yuan. Space-Time Coding[M]. USA:John Wiley & Sons Ltd,2003.25-28.
[39]R. A. Horn, C. R. Johnson. Matrix Analysis[M]. New York:Cambridge University Press,1991. 58-60.
[40]S. M. Alamouti. A simple transmitter diversity scheme for wireless communications[J]. IEEE Journal on Selected Areas in Communications,1998,16(8):1451-1458.
[41]Andrea Goldsmith. Wireless Communications[M]. UK:Cambridge University Press,2005. 489-490.
[42| W. Lee. Mobile Communications Engineering[M]. New York:McGraw-Hill.1982.398-370.
[43]Laneman J.N., Tse D. Wornell G.W.. Cooperative Diversity in Wireless Networks:Efficient Protocols and Outage Behavior[J]. IEEE Transactions on Information Theory,2004,50(12): 3062-3080.
[44]Hunter T.E.. Coded Cooperation:A New Framework for User Cooperation in Wireless Networks[D]. Texas:the University of Texas at Dallas,2004.
[45]R. U. Nabar, H. Boelcskei, F. W. Kneubhueler. Fading relay channels:performance limits and space-time signal design[J]. IEEE J. Select. Areas Communication,2004,22(6):1099-1109.
[46]A. Stefanov, E. Erkip. Cooperative coding for wireless networksp[J]. IEEE Trans. Commun,2004, 52(9):1470-1476.
[47]R. U. Nabar, H. Boleskei, F. W. Kneubuhler. Fading relay channels:Performance limits and space-time signal design[J]. IEEE J. Select. Areas Commun.,2004,22(6):1099-1109.
[48]J. N. Laneman, G. W. Wornell. Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks[J]. IEEE Trans. Inform. Theory,2003,49(10):2415-2425.
[49]A. Stefanov, E. Erkip. Cooperative space-time coding for wireless networks[J]. IEEE Trans. Commun,2005,53(11):1804-1809.
[50]董波LDPC编码的分布式空时合作通信系统[D].杭州：浙江大学,2006.
[51]Y. Li, B. Vucetic, T. Wong, et. al. Distributed turbo coding with soft information relaying in multihop relay networks[J]. IEEE J. Select. Areas Commun.,.2006,24(11):2040-2050.
[52) S. Jeon, S. H. Lee, A relay-assisted handover technique with network coding over Multihop cellular networks[J]. IEEE Commun. Letter,2007,11(3):252-254.
[53]Scndonaris A., Erkip E., Aazhang B. User cooperation diversity Part Ⅰ-System description[J]. IEEE Transactions on Communications,2003,51(11):1927-1938.
[54]Sendonaris A., Erkip E., Aazhang B. User cooperation diversity Part Ⅱ-Implementation aspects and performance analysis[J]. IEEE Transactions on Communications,2003,51(11):1939-1948.
[55]Ahlswede R, Cai N, Li S Y R, et al. Network Information Flow[J]. IEEE Trans.on Information Theory,2000,46(4):1204-1216.
[56]K. B. Letaief, W. Zhang. Cooperative communications for cognitive radio networks[J]. Proc IEEE, 2009,97(5):1-16.
[57]O. Simeone, U. Spagnolini, Y. Bar-Ness. Stable throughput of cognitive radios with and without relaying capability[J]. IEEETrans..Commun.,2007,55(12):2351-2360.
[58]O. Simeone, L. Stanojev, S. Savazzi, et.al. Spectrum leasing to cooperative secondary ad hoe networks[J]. IEEE J. Select. Areas Commun.,2008,26(1):203-213.
[59]Q. Zhang, J. Jia, J. Zhang. Cooperative relay to improve diversity in cognitive radio networks|JJ. IEEE Commun. Mag,2009,47(2):111-117.
[2]Jakes W.C.. Ed. Microwave Mobile Communications[M]. New York:Wiley,1976.187-188.
[3]FCC. Notice of Proposal rule making and order, ET Docket No 03-222 [R]. USA:FCC,2003.
[4]J.Mitola. G.Q.Maguire. Cognitive Radio:Making software radios more personal[J]. Journal of IEEE of Communication,1999,6(4):13-18.
[5]FCC. Spectrum policy task force report, ET Doeket No.02---155[R]. USA:FCC,2002.
[6]Zou Yulong, Zhu Jia, Zheng Baoyu, et al. An Adaptive Cooperation Diversity Scheme With Best-Relay Selection in Cognitive Radio Networks[J]. IEEE TRANSACTIONS ON SIGNAL PROCESSING,2010,58(10):5438-5445.
[7]Li Liying, Zhou Xiangwei, Xu Hongbing, et al. Simplified Relay Selection and Power Allocation in Cooperative Cognitive Radio Systems[J]. IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS,2011,10(1):33-36.
[8]Si JiangBo, Li Zan, Chen XiaoJun, et al. On the Performance of Cognitive Relay Networks Under Primary User's Outage Constraint[J]. IEEE COMMUNICATIONS LETTERS,2011,15(4): 422-424.
[9]Yulong Zou, Yu-Dong Yao, Baoyu Zheng. Cognitive Transmissions with Multiple Relays in Cognitive Radio Networks[J]. IEEE Transactions on Wireless Communications,2011,10(2): 648-659.
[10]Hsien-Po Shiang, van der Schaar M.. Distributed Resource Management in Multihop Cognitive Radio Networks for Delay-Sensitive Transmission[J]. IEEE Transactions on Vehicular Technology,2009,58(2):941-953.
[11]Ubaidulla P., Aissa, S.. Optimal Relay Selection and Power Allocation for Cognitive Two-Way Relaying Networks[J]. IEEE Transactions on Wireless Communications,2012,1(3):225-228.
[12]Jung-Bin Kim, Dongwoo Kim. Outage Probability and Achievable Diversity Order of Opportunistic Relaying in Cognitive Secondary Radio Networks[J]. IEEE Transactions on Communications,2012,60(9):2456-2466.
[13]刘云学.认知无线电中的频谱感知技术研究[D].山东：山东大学,2009.
[14]Haykin. Cognitive radio:brain-empowered wireless communications[J]. IEEE Journal on Selected Areas in Communications,2005,23(2):201-220.
[15]段志刚.协作通信在认知无线电中的应用研究[D].山东：山东大学,2010.
[16]ABRAMSON N. THE ALOHA SYSTEM:another alternative for computer communications[A]. In:Proceedings of fall joint computer conferencc[C]. New York, US:1970.281-285.
[17]CORDEIRO C, CHALLAPALI K, BIRRU D, et al. the first worldwide wireless standard based on cognitive radios. Baltimore[M]. Maryland:IEEE,2005.328-337.
[18]周小飞,张洪钢.认知无线电原理及应用[M].北京：北京邮电大学出版社,2007.458-461.
[19]Craig Partridge. The XG Vision. V 2.0[HB/OL]. http://www.ir.bbn.com/projects/xmac/vision.html,2012-5-16.
[20]王金龙,吴启辉,龚玉萍,等.认知无线网络[M].北京：机械工业出版社,2010.345-346
[21]Motorola. End-to-End re-configurability, E2R_WP5_D5.3050727[EB/OL]. http://e2r.motlabs.com/Deliverables/H2R_WP5 D5.3050727.pdf,2012-5-16.
[22]Simon Delaere. E3 project [EB/OL]. http://ict-e3.eu/,2012-5-16.
[23]朱江.频谱感知算法及授权用户用频行为研究[D].武汉：华中科技大学,2010.
[24]Senhua H, Zhi D., Xin L. Non-Intrusive Cognitive Radio Networks Based on Smart Antenna Technology[A]. In:Global Telecommunications Conference[C]. IEEE, USA:2007.4862-4867.
[25]Guodong Z., Jun M, Ye L, et al. Spatial Spectrum Holes for Cognitive Radio with Directional Transmission [A]. In:Global Telecommunications Conference [C]. IEEE, USA:2008.1-5.
[26]Karama Hamdi, Khaled Ben Letaief. Power, sensing time, and throughput tradoffs in cognitive radio systems:a cross-layer approach[A]. In:IEEE 2009 Wireless Communications and Networking Conference[C]. IEEE, USA:2009.1-5.
[27]FCC. Notice of Proposed Rule Making and Order, ET Docket No.03-322[R]. USA:FCC,2003.
[28]FCC. Spectrum Policy task force report, ET Docket No.02-155[R]. USA:FCC,2002.
[29]Lin Shufang, Fang Xuming. Two-level Game Based Spectrum Lease Framework in Cognitive Radio Networks[A]. In:Communication Systems[C]. IEEE, USA:2008.104-108.
[30]Wu Yongle, Wang Beibei, Liu K, Clancy T.C.. A Multi-Winner Cognitive Spectrum Auction Framework with Collusion-Resistant Mechanisms[A]. In:New Frontiers in Dynamic Spectrum Access Networks[C]. IEEE, USA:2008.1-9.
[31]Tang Pak Kay, Chew Yong Huat, Ong Ling Chuen, et al. On the Grade-of-Services in the Sharing of Radio Spectrum[A]. In:Cognitive Radio Oriented Wireless Networks and Communications[C]. IEEE, USA:2007.85-89.
[32]Wang Weidong, Wang Ben, Zhang Yinghai, et al. A Novel System Model based on Cost-prediction for Spectrum Leasing in Cognitive Radio[J]. China Communications,2010,7(2):25-26.
[33]Z. Ji, K. Liu. Cognitive radios for dynamic spectrum access-dynamic spectrum sharing:a game theoretical overview[J]. IEEE Communication Magazine,2007,53(8):88-94.
[34]Wang Jiao, Huang Yuqing, Jiang Hong. Improved Algorithm of Spectrum Allocation Based on Graph Coloring Model in Cognitive Radio[A]. In:Comunications and Mobile Computing[C]. USA: 2009.353-357
[35]Anh Tuan Hoang, Ying-Chang Liang. Maximizing Spectrum Utilization of Cognitive Radio Networks Using Channel Allocation and Power Control[A]. In:Vehicular Technology Conference[C]. USA:2006.1-5.
[36]T. Cover, A. El Gamal. Capacity theorems for the relay channel[J]. IEEE Trans. Inform. Theory, 1979,25(3):572-584.
[37]郑侃,彭岳星,龙航,等.协作通信及其在LTE-Advanced中的应用[M].北京：人民邮电出版社,2010.17-18.
[38]B. Vucetic, J. Yuan. Space-Time Coding[M]. USA:John Wiley & Sons Ltd,2003.25-28.
[39]R. A. Horn, C. R. Johnson. Matrix Analysis[M]. New York:Cambridge University Press,1991. 58-60.
[40]S. M. Alamouti. A simple transmitter diversity scheme for wireless communications[J]. IEEE Journal on Selected Areas in Communications,1998,16(8):1451-1458.
[41]Andrea Goldsmith. Wireless Communications[M]. UK:Cambridge University Press,2005. 489-490.
[42| W. Lee. Mobile Communications Engineering[M]. New York:McGraw-Hill.1982.398-370.
[43]Laneman J.N., Tse D. Wornell G.W.. Cooperative Diversity in Wireless Networks:Efficient Protocols and Outage Behavior[J]. IEEE Transactions on Information Theory,2004,50(12): 3062-3080.
[44]Hunter T.E.. Coded Cooperation:A New Framework for User Cooperation in Wireless Networks[D]. Texas:the University of Texas at Dallas,2004.
[45]R. U. Nabar, H. Boelcskei, F. W. Kneubhueler. Fading relay channels:performance limits and space-time signal design[J]. IEEE J. Select. Areas Communication,2004,22(6):1099-1109.
[46]A. Stefanov, E. Erkip. Cooperative coding for wireless networksp[J]. IEEE Trans. Commun,2004, 52(9):1470-1476.
[47]R. U. Nabar, H. Boleskei, F. W. Kneubuhler. Fading relay channels:Performance limits and space-time signal design[J]. IEEE J. Select. Areas Commun.,2004,22(6):1099-1109.
[48]J. N. Laneman, G. W. Wornell. Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks[J]. IEEE Trans. Inform. Theory,2003,49(10):2415-2425.
[49]A. Stefanov, E. Erkip. Cooperative space-time coding for wireless networks[J]. IEEE Trans. Commun,2005,53(11):1804-1809.
[50]董波LDPC编码的分布式空时合作通信系统[D].杭州：浙江大学,2006.
[51]Y. Li, B. Vucetic, T. Wong, et. al. Distributed turbo coding with soft information relaying in multihop relay networks[J]. IEEE J. Select. Areas Commun.,.2006,24(11):2040-2050.
[52) S. Jeon, S. H. Lee, A relay-assisted handover technique with network coding over Multihop cellular networks[J]. IEEE Commun. Letter,2007,11(3):252-254.
[53]Scndonaris A., Erkip E., Aazhang B. User cooperation diversity Part Ⅰ-System description[J]. IEEE Transactions on Communications,2003,51(11):1927-1938.
[54]Sendonaris A., Erkip E., Aazhang B. User cooperation diversity Part Ⅱ-Implementation aspects and performance analysis[J]. IEEE Transactions on Communications,2003,51(11):1939-1948.
[55]Ahlswede R, Cai N, Li S Y R, et al. Network Information Flow[J]. IEEE Trans.on Information Theory,2000,46(4):1204-1216.
[56]K. B. Letaief, W. Zhang. Cooperative communications for cognitive radio networks[J]. Proc IEEE, 2009,97(5):1-16.
[57]O. Simeone, U. Spagnolini, Y. Bar-Ness. Stable throughput of cognitive radios with and without relaying capability[J]. IEEETrans..Commun.,2007,55(12):2351-2360.
[58]O. Simeone, L. Stanojev, S. Savazzi, et.al. Spectrum leasing to cooperative secondary ad hoe networks[J]. IEEE J. Select. Areas Commun.,2008,26(1):203-213.
[59]Q. Zhang, J. Jia, J. Zhang. Cooperative relay to improve diversity in cognitive radio networks|JJ. IEEE Commun. Mag,2009,47(2):111-117.