用户名: 密码: 验证码:
基于MIMO OFDM无线资源管理技术的研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
第四代移动系统包含多种关键性的技术,其中多入多出(MIMO)和正交频分复用(OFDM)是最有前景的两项物理层技术。MIMO技术能够极大的提高系统容量,而OFDM技术能够抵抗多径干扰,因此MIMO OFDM技术能够为未来移动通信网络提供最强劲的空中接口支撑。然而,频谱资源的日趋紧张,使得运营商提供无线多业务服务需要付出昂贵的频谱费用。因此,频谱效率是决定采用一种技术的非常重要的因素,对B3G系统也是如此。无线资源管理的目标就是在满足用户QoS需求的情况下,在有限的带宽上最大限度地提高频谱效率和系统容量,同时避免网络拥塞的发生。因此,本文主要研究基于MIMO OFDM系统的无线资源管理技术。
     系统容量对于无线资源管理的研究具有指导意义,因此本文首先研究了MIMO OFDM系统的容量。利用MIMO OFDM信道在空时频三维衰落的特性,提出了空时频三维注水算法,即在空时频三维进行功率分配。因此,同空频注水算法和等功率分配算法相比,该算法可以获得最大的各态历经信道容量。同时,相对于空频注水算法来说,由于空时频注水水平的计算是基于信道的统计状态信息,因此其需要反馈的信道状态信息量少,而且对于平坦衰落和频率选择性衰落信道都适用。另外,由于不需要每个功率分配间隔都计算注水水平,因此,空时频注水水平的计算复杂度也要低很多。
     按照七层协议的定义标准,目前,MIMO OFDM无线资源管理技术的研究成果主要集中在物理层以及PHY-MAC跨层分配上。本文首先在物理层对MIMO OFDM波束成型系统的无线资源管理技术进行了研究。通过对几种MIMO OFDM波束成型技术进行性能分析,考虑到各种因素,本文采用直接共享的波束成型方式,其实质上是选定了空分多址(SDMA)的方式。接下来,建立了OFDMA-SDMA MIMO OFDM波束成型系统无线资源管理的数学模型。该模型不仅考虑了空间上的多用户分集,还考虑到每个子载波的多个空间信道同时进行并行传输以最大限度的提高资源利用率。在这里,每个子载波和它的空间子信道的组合被定义为一组空频子信道。比较遗憾的是,由于存在同信道干扰,该问题在数学上是个NP-hard的问题。为了解决这个问题,我们提出了次优的空频子信道分配方案。该方案分为三个步骤:第一,假设不存在子载波共享,经过推导,我们获得最佳的空频子信道分配方案;第二,基于第一步的子载波分配结果,在空间相关性足够小的用户之间进行子载波共享;第三步,逐个用户在所有的空频子信道上进行比特加载和功率分配。为了使得空频子信道分配算法更为实用化,本文又提出了一种实用的空频子信道分配算法。该算法对于每个子载波基于次优算法中推导出的子载波分配表达式给出新的子载波分配因子,利用该子载波分配因子进行子载波分配,简化了计算复杂度。同时,结合自身的特点和反馈信息量降低的要求,又提出了一种插值波束成型反馈方案,以使得实用化算法在限制反馈的信道条件下也能使用。
     跨层资源分配算法既考虑了上层的业务QoS特性,又考虑底层信道状态,成为无线通信系统中比较有效的资源调度方式。本文研究了基于MIMO OFDM技术的IEEE 802.16系统中的跨层资源调度算法。跨层设计有两种理念:第一,自下而上,将下层信道信息传递到上层,在上层进行资源调度;第二,自上而下,将上层业务的QoS要求映射到下层,在下层进行资源分配。在本文中,QoS保证的公平性算法属于自下而上的方式,即将等效信道增益映射到上层来代表信道状态。然后综合考虑业务QoS需求、调度器的状态、业务的公平性以及信道状态,定义子信道分配因子,利用该子信道分配因子进行资源块的分配,最后对每个连接进行比特加载和功率分配。而QoS保证的最优化调度算法则是基于自上而下的思想,即将上层实时业务对时延的要求转换为物理层对实时业务的最低调度速率的要求,从而将资源调度问题放到物理层来做。以最大化系统容量为目标,通过在物理层求解,获得了最优化的子载波、比特和功率分配方案。仿真结果表明,这两种方案,QoS保证的公平性算法的系统吞吐量要小于QoS保证的最优化算法,但是前者的公平性要好于后者。
The 4~(th) wireless communication system proposed many novel technologies, the most important two of which are multi-input multi-output (MIMO) and orthogonal frequency division multiplexing (OFDM). MIMO can provide a huge amount of the system capacity and OFDM can well defeat the inter-symbol interference (ISI), hence the combination of MIMO and OFDM must be the strongest air interface technology for the 4~(th) wireless communication. However, the frequency resource will become more and more emergent for guaranteed QoS requirements of various services. The frequency efficiency always decides the commercialization of a technology and The 4~(th) wireless communication system is no expectation. Radio resource management (RRM) is just a technology devoting to improve the frequency efficiency and providing QoS guarantees for any service. Hence, in this dissertation, we mainly focus on researches of the radio resource management in MIMO OFDM systems.
     The channel capacity can give some instruments to RRM. Hence, we first discuss the ergodic capacity of MIMO OFDM systems. The space-time-frequency waterfilling scheme (STFWF) is proposed to maximize the ergodic capacity through allocating power in the space, time and frequency domains. It keeps the long-term power constant and allows the short-term power fluctuating. Compared with space-frequency waterfilling scheme, STFWF scheme has the following merits. Since the waterfilling level is calculated based on long-term channel information in the STFWF scheme, the channel statistic information is only needed which can reduce the feedback information and computational complexity. Furthermore, it can suit both flat and frequency selective fading channel.
     At present, RRM schemes in MIMO OFDM systems are mainly focused on PHY layer and PHY-MAC cross layer. We first make some researches on RRM in MIMO OFDM beamforming systems at PHY layer. After doing some performance analyses on several kinds of beamforming technologies, the subcarrier shared directly one is chosen to provide SDMA among multiuser. Then, the RRM mathematical module is set up in OFDMA-SDMA MIMO OFDM systems. It is different from the conventional ones by considering both space multiuser diversity and all the space subchannels for each subcarrier. Hence, it improves the frequency efficiency to the largest extent. Here, each subcarrier and its space subchannels are defined as a group of space-frequency subchannels. Unfortunately, it is a NP-hard problem from mathematical viewpoint. Hence, the suboptimal space-frequency subchannel allocation and adaptive modulation (SSFSA) is proposed which divides the RRM problem into three steps. First, subcarriers are not shared among users and the optimal space-frequency subchannel allocation outcome is obtained by mathematical deduction. Then, based on the subcarrier allocation in the first step, the subcarriers sharing scheme is proposed to share subcarriers among users with low spatial correlation at the premise that negligible co-channel interferences are introduced. Bit loading and power allocation are made at the third step for each user on its all space-frequency subchannels. Considering the computational complexity of SSFSA and feedback information reduction, a practical space-frequency subchannel allocation and adaptive modulation (PSFSA) is also proposed. This scheme defines an initial subcarrier allocation factor based on the first step subcarrier allocation outcome of SSFSA. It can reduce the computational complaexity to init subcarrier allocation according to the factor. An improved interpolation-based beamforming algorithm is also proposed to reduce the feedback information in PSFSA.
     Since considering both the QoS characteristics at the upper layer and the channel information at the PHY layer, cross layer RRM is an efficient method to manage resources in wireless networks. We make some researches on cross layer RRM in IEEE 802.16 MIMO OFDM systems. There are two ways to realize cross layer RRM. The first one is mapping channel information from PHY layer to upper layer and executing RRM at the upper layer. The other one is mapping QoS parameters to PHY layer and allocate resources at the PHY layer. The proposed QoS-guaranteed fairness scheme is the first type which mapping the channel fading information to the MAC layer. The subchannel allocation untility function is defined considering QoS requirements of different services, the status of scheduler, the fairness among connections and the channel fading status. The subchannel is allocated to the connection with the largest subchannel allocation unility and then bit and power allocations are made for each connection. While the optimal QoS-guaranteed resource allocation scheme belongs to the second one which maps the upper rtPS delay requirements to scheduling rate requirements. And then, the capacity-maximized resource allocation problem with scheduling and power constraints is solved by mathematical deduction. From the simulation results in Matlab, the system throughput of QoS-guaranteed fairness scheme is less than that of the optimal QoS-guaranteed resource allocation scheme, while the fairness of the former is better than the later.
引文
[1]中华人民共和国信息产业部网站 http://www.mii.gov.cn
    [2]ITU-R M.687 "International Mobile Telecommunications-2000(IMT-2000),"http://www.itu.int
    [3]ITU-R M.1457 "Detailed specifications of the radio interfaces of International Mobile Telecommunications-2000(IMT-2000)," http://www.itu.int
    [4]WCDMA空中接口系列规范 http://www.3gpp.org/spec/
    [5]CDMA2000空中接口系列规范 http://www.3gpp2.org/spec/
    [6]ITU-R M.1645(06/03) "Framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000," http://www.itu.int
    [7]ITU-R M.2038(2004) "Technology Trends," http://www.itu.int
    [8]R.W.Chang,"Synthesis of band-limited orthogonal signals for multichannel data transmission," Bell Systems Technical Journal,vol.46,pp.1775-1796,December 1996.
    [9]S.B.Weinstein and P.M.Ebert,"Data transmission by frequency division multiplexing using the discrete fourier transform," IEEE Transactions on Communication Technology,vol.COM-19,pp.628-634,October 1971.
    [10]Institute of Electrical and Electronics Engineers(IEEE) 802 standards,Web site, www.ieee802.org,2004
    [11]Digital Video Broadcasting(DVB) Web site,www.dvb.org,Jan.2002
    [12]J.Khun-Jush,P.Schramm,G Malmgren and J.Torsner,"HiperLAN2:Broadband wireless communications at 5GHz," IEEE Commun.Mag.,vol.40,no.6,June 2002
    [13]J.Winter,"Smart antennas for wireless systems," IEEE Pers.Comm.Mag.,vol.5,pp.23-27,Feb.1998.
    [14]Pramod Viswanath,David N.C.Tse and Rajiv Laroia,"Opportunistic Beamforming Using Dumb Antennas," IEEE Transactions on Information Theory,vol.48,no.6,pp.1277-1294,June 2002.
    [15]J.H.Winters,"The Diversity Gain of Transmit Diversity in Wireless systems with Rayleigh Fading," Proc.1994 ICC/SUPERCOMM,pp.1121-1125,February 1994.
    [16]Branka Vucetic and Jinhong Yuan,Space-Time Coding,New York:Wiley,2003
    [17]J.Jiang,R.M.Buehrer,and W.H.Tranter,"High-speed downlink packet transmission with spatial multiplexing and scheduling," Proc.of IEEE WCNC 2004,pp.2148-2152,Mar 2004.
    [18]A.Sampath et.al,"Power control and resource management CDMA wireless system," Proc.of IEEE PIMRC,pp.21-25,1995.
    [19]Wei Zhuang,B.Bensaou and Kee Chaing Chua,"Adaptive quality of service handoff priority scheme for mobile multimedia networks," IEEE Transactions on Vehicular Technology,vol.49,pp.494-505,March 2000.
    [20]W.Y.Kuo and M.P.Fitz,"Design and analysis of transmitter diversity using intentional frequency offset for wireless communications," IEEE Trans.Veh.Technol.,vol.46,pp.871-881,Nov.1997.
    [21]P.Bender,et al.,"CDMA/HDR:A Bandwidth-Efficient High-Speed wireless data service for nomadic users," IEEE Communication Magazine,pp.70-77,2000.
    [22]Jang Jiho,Lee Kwang Bok and Lee Yong-Hwan,"Transmit Power and Bit Allocations for OFDM Systems in a Fading Channel," Proc.of IEEE GLOBECOM,pp.858-862,2003.
    [23]余官定,张朝阳,仇佩亮,OFDM系统功率和比特分配算法研究,电子与信息学报,pp.1479-1482,2005.
    [24]R.Grunheid and H.Rohling,Adaptive Wireless Transceivers,John Wiley and Sons,2002.
    [25]R.Grunheid,E.Bolinth and H.Rohling,"A Blockwise Loading Algorithm for the Adaptive Modulation Technique in OFDM Systems," Proc.of IEEE VTC,pp.948-951,2001.
    [26]C.Y.Wong,et al,"Multiuser OFDM with adaptive subcarrier,bit and power allocation," IEEE JSAC,vol.17,no.10,pp.1747-1758,Oct.1999.
    [27]Ehsan Bakhtiari and Babak H.Khalaj,"A new joint power and subcarrier allocation scheme for multiuser OFDM systems," Proc.of IEEE PIMRC,pp.1959-1963,2003.
    [28]Guodong Zhang,"Subcarrier and bit allocation for real-time services in multiuser OFDM systems," IEEE Communications Society,pp.2985-2989,2004.
    [29]C.Y.Wong,C.Y.Tsui,R.S.Cheng and K.B.Letaief,"A real-time subcarrier allocation scheme for multiple access downlink OFDM transmission," Proc.of IEEE VTC'99,pp.1124-1128,1999.
    [30]Yung-Fang Chen,Jean-Wei Chen and Chih-Peng Li,"A fast suboptimal subcarrier,bit and power allocation algorithm for multiuser OFDM-based systems," IEEE Communications Society,pp.3212-3216,2004.
    [31]Y.H.Lee and et al,"On the use of linear programming for dynamic subchannel and bit allocation in multiuser OFDM," Proc.of IEEE GLOBECOM,pp.3648-3652,2001.
    [32]Lan Wang and Zhisheng Niu,"Computationally efficient resource allocation algorithm for multiuser OFDM systems," Asia-pacific Conference on Communications,Perth,Western Australia,pp.3-5,Oct.2005.
    [33]S.Pietrzyk and G.J.M.Janssen,"Multiuser subcarrier allocation for QoS provision in the OFDMA systems," Proc.of IEEE VTC,pp.1077-1081,2002.
    [34]Yongxue Wang,Fangjiong Chen and Gang Wei,"Adaptive subearrier and bit allocationfor multiuser OFDM system based on genetic algorithm," Proc.of IEEE ICCCAS,pp.242-246,2005.
    [35]P.S.Chow,J.M.Cioffi and J.C.Bingham,"A practical discrete multitone transceiver loading algorithm for data transmission over spectrally shaped channels," IEEE Trans.on Communication,vol.43,no.2,pp.773-775,1995.
    [36]Long Gao,et al.,"A Low-Complexity Adaptive Bit and Power Allocation Algorithm for MIMO-OFDM Systems," Proc.of IEEE ISCIT,Beijing,China, pp.542-545,2005.
    [37]Robert F.H.Fisher and Johanes B.Huber,"A new loading algorithm for discrete multitone transmission," Proc.of IEEE Globecom 1996,London,pp.724-728,Nov.1996.
    [38]Antonio Pascual-Iserte and Ana I.Perez-Neira,"On power allocation strategies for maximum signal to noise and Interference ratio in an OFDM-MIMO system,"IEEE Trans.on Communication,vol.3,no.3,May 2004.
    [39]A.Pascual-Iserte,A.I.Pdrez-Neira,and M.A.Lagunas,"Pre and post beamforming in MIMO channels applied to HIPERLAN/2 and OFDM,"in Proc.IST Mobile&Wireless Communications Summit,Barcelona,Spain,pp.3-8,Sep.2001.
    [40]J.Yang and S.Roy,"On joint transmitter and receiver optimization for multiple-input-multiple-output(MIMO) transmission systems," IEEE Trans.on Common,vol.42,pp.3221-3231,Dec.1994.
    [41]X.Liu,E.K.P.Chong,N.B.Shroff,"Opportunistic Transmission Scheduling with Resource-Sharing Constraints in Wireless Networks,"IEEE JSAC.,pp.2053-2064,2001.
    [42]Lan Tang,Shuxun Wang,and Yingchang Liang,"Variable-rate Adaptive Modulation in MIMO System Exploiting Multiuser Diversity," Proc.of IEEE ICASSP,Montreal,Que,Canada,pp.693-696,2004.
    [43]Kaiming Liu,Feifei Yin and Wenbo Wang,"An Efficient Greedy Loading Algorithm for Adaptive Modulation in OFDM Systems," Proc.of IEEE PIMRC,Berlin,Germany,pp.1130-1134,2005.
    [44]Yung-Fang Chen,Jean-Wei Chen and Chih-Peng Li,"A Fast Suboptimal Subcarrier,Bit,and Power Allocation Algorithm for Multiuser OFDM-based Systems,"Proc.of IEEE ICC,Paris,France,pp.3212-3216,2004
    [45]W.Rhee,J.M.Cioffi,"Increase in Capacity of Multiuser OFDM System Using Dynamic Subchannel Allocation," Proc.of IEEE VTC,Tokyo,Jpn,pp.1085-1089,2000.
    [46]J.Jang,K.B.Lee,"Transmit Power Adaptation for Multiuser OFDM Systems," IEEE J.Selected Areas Comm.,pp.171-178,2003.
    [47]Chengkang Pan,yueming Cai and Youyun Xu,"Adaptive subcarrier and power allocation for multiuser MIMO-OFDM systems," Proc.of IEEE ICC,pp.2631-2635,2005.
    [48]Long Gao,Zhengdong Luo and Bihua Tang,“A low-complexity adaptive bit and power allocation algorithm for MIMO-OFDM systems”,Proc of IEEE ISCIT,2005.
    [49]Lan Wang and Zhisheng Niu,“Computationally efficient resource allocation algorithm for multiuser OFDM systems,” Asia-pacific Conference on Communications,Perth,Western Australia,pp.3-5,Oct.2005.
    [50]Ying Jun Zhang and K.B.Letaief,“Optimizing power and resource management for multiuser MIMO/OFDM systems,” Proc of IEEE GLOBECOM,pp.179-183,2003.
    [51]H.W.Khun,“The Hungarian method for the assignment problem,” Naval Research Logistics Quarterly,pp.83-97,1955.
    [52]张春玲,葛建华,张海滨,“多用户MIMO-OFDM系统中一种子载波分配算法”,电讯技术,2006年第5期,pp.71-73.
    [53]Peerapong Uthansakul and Marek E.Bialkowski,“An efficient adaptive power and bit allocation algorithm for MIMO OFDM system operating in a multiuser environment,” Proc of IEEE VTC,pp.1531-1535,2006.
    [54]Guoting Lai,Junxun Yin,Fan Lin and Huawen Yu,“Performance of adaptive bit and power allocation MIMO-OFDM system based on greedy algorithm,”Proc.of IEEE WCNM,pp.44-49,2005.
    [55]Peter W.C.Chan and Roger S.K.Cheng,“Reduced-complexity power allocation in zero-forcing MIMO-OFDM downlink system with multiuser diversity,”Proc,of IEEE ISIT,pp.2320-2324,2005.
    [56]Francese Rey,Meritexell Lamarca and Gregori Vazquez,“Robust power allocation algorithms for MIMO-OFDM systems with imperfect CSI,”IEEE transactions on signal processing,vol.53,no.3,Mar.2005.
    [57]Jia Tang and Xi Zhang,“Link-adaptation-enhanced dynamic channel allocation for MIMO-OFDM wireless networks,” Proc of IEEE WCNC,pp.1126-1131,2005
    [58]Ya-Han Pan,Khaled Ben Letaief and Zhigang Cao,“Dynamic spatial subchannel allocation with adaptive beamforming for MIMO-OFDM Systems,”IEEE transaction on wireless communications,vol.3,no.6,Nov.2004.
    [59]Ying Jun Zhang and Khaled Ben Letaief,“Adaptive resource allocation for multi-access MIMO-OFDM systems with matched filtering,”IEEE transaction on communications,vol.53,no.11,Nov.2005.
    [60]H.Yin,H.Liu,"An Efficient Multiuser Loading Algorithm for OFDM-based Broadband Wireless Systems," Proc.of IEEE GLOBECOM,San Francisco,CA,USA,pp.103-107,2000.
    [61]K.B.Letaief and Y.J.Zhang,"Dynamic Multi-user Resource Allocation and Adaptation for Wireless Systems," IEEE Trans.Wireless Commun,Aug 2006.
    [62]A.K.F.Khattab and K.M.F.Elsayed,"Opportunistic scheduling of delay sensitive traffic in OFDMA-based wireless networks," Proc.of Int.Symp.World of Wireless Mobile and Multimedia Networks,Buffalo,NY,pp.10-19,2006.
    [63]P.Bender,P.Black,M.Grob,R.Padovani,N.Sindhushayana,and A.Viterbi,"CDMA/HDR:A Bandwidth-Efficient High-Speed Wireless Data Service for Nomadic Users," IEEE Commun.Mag.,vol.38,pp.70-77,Jul.2000.
    [64]H.Kim and Y.Han,"A proportional fair scheduling for multicarrier transmission systems," IEEE Commun.Lett.,vol.9,pp.210-212,Mar.2005.
    [65]P.Liu,R.Berry,and M.L.Honig,"Delay-Sensitive PacketScheduling in Wireless Networks," Proc.of IEEE WCNC 2003,vol.3,pp.1627-1632,Mar.2003.
    [66]G.Song and Y.Li,"Adaptive Resource Allocation Based on Utility Optimization in OFDM," Proc.of IEEE GLOBECOM 2003,vol.2,pp.586-90,Dec.2003.
    [67]Zhang ying-jun and KHALED Ben Letaief,"Cross layer adaptive resource management for wireless packet networks with OFDM signaling," IEEE Trans.on Wireless Commun.,pp.3244-3254,2006.
    [68]Y.J.Zhang and S.C.Liew,"Link-adaptive largest-weighted-throughput packet scheduling for real-time traffics in wireless OFDM networks," Proc.of IEEE Global Telecommunications Conf.,St.Louis,MO,vol.5,pp.5-9,2005.
    [69]Weilan Huang and K.B.Letaief,"A cross-layer resource allocation and scheduling for multiuser space-time block coded MIMO-OFDM systems,"Proc.of IEEE ICC,pp.2655-2659,2005
    [70]Jia Tang and Xi Zhang,"Cross-layer design of dynamic resource allocation with diverse QoS guarantees for MIMO-OFDM wireless networks," Proc.of IEEE WoWMoM,pp.205-212,2005.
    [1]Richard van Nee and Ramjee Prasad,OFDM for Wireless Multimedia Communications,Artech House,Boston London,2000.
    [2]佟学俭,罗涛,“OFDM移动通信技术原理与应用”,人民邮电出版社,2003年6月.
    [3]王文博,郑侃,“宽带无线通信OFDM技术”,人民邮电出版社,北京,2003年11月.
    [4]Paulraj Arogyaswami,Nabar Rohit and Gore Dhananjay,Introduction to Space-Time wireless communications,Cambridge University Press,2003.
    [5][美]Theodore S.Rappaport著,蔡涛,李旭,杜振民译《无线通信原理与应用》,电子工业出版社,1999年11月第1版.
    [6]J.B.Andersen,T.S.Rappaport and S.Yoshida,"Propagation measurements and models for wireless communication channels," IEEE Commun.Mag.,vol.33,no.1,pp.42-49,Jan.1995.
    [7]T.S.Rappaport,Wireless Communications:Principles and Practice,Prentice Hall,1996.
    [8]G..L.Stuber,Principles of Mobile Communications,2nd edition,Kluwer Academic Publishers,2000.
    [9]Proakis J.Ca..,Digital Communications.Third Edition,McGraw-Hill,1995.
    [10]W.C.Jakes,Microwave Mobile Communications,IEEE Press,Piscataway,1993.
    [11]侯晓林,“宽带无线移动通信系统中信道估计的研究”,博士学位论文,北京邮电大学,2005年4月.
    [12]Jeruchim C.Michel,Simulation of Communication System:Modeling,Methodology and Techniques,Kluwer Academic/Plenum Publishers.
    [13]D.Gesbert,H.Bolcskel,D.Gore,"MIMO Wireless Channels:Capacity and Performance Prediction," Proc.of IEEE GLOBECOM,pp.1083-1088,2000.
    [14]D.CHIZHIK,G.J.FOSCHINI and R.A.VALENZUEL,"A Capacities of Multi-Element Transmit and Receive Antennas:Con'elations and Keyholes,"IEEE Electronics Letters,pp.1099-1100,2000.
    [15]D.P.Palomar,"A Unified Framework for Communications through MIMO Channels," Thesis,University Politcnica de Catalunya,May 2003.
    [16]Jonathan Duplicy Louveaux,"Interference-free Multi-user MIMO-OFDM,"Proc.of IEEE ICASSP,Philadelphia,PA,United States,pp.1149-1152,2005.
    [17]Lai-U Choi and R.D.Murch,"A Transmit Preprocessing Technique for Multiuser MIMO Systems Using a Decomposition Approach," IEEE Trans.on Wireless Commun.,pp.20-24,2004.
    [18]H.Rohling,R.Gr(u|¨)nheid,"Performance of an OFDM-TDMA Mobile Communication System," Proc.ofIEEE VETEC,pp.1589-1293,1996.
    [19]Justin Chuang,Nelson Sollenberger etc.,"High-Speed Wireless Data Access Based on Combining EDGE with Wideband OFDM," IEEE Communications Magazine,pp.92-98,November 1999.
    [20]R.Van Nee et al.,"New High-rate Wireless LAN Standards," IEEE Commun. Mag.,vol.37,no.12,pp.82-88,Dec.1999.
    [21]Justin Chuang and Nelson Sollenberger,"Beyond 3G Wideband Wireless Data Access Based on OFDM and Dynamic Packet Assignment," IEEE Communications Magazine,pp.78-87,July 2000.
    [22]H.Yin and H.Liu,"An efficient multiuser loading algorithm for OFDM-based broadband wireless systems," Proc.of IEEE Globecom,San Francisco,USA,2000.
    [23]V.I.Roman,"Frequency Reuse and System Deployment in Local Multipoint Distribution Service," IEEE Pers.Commun.,vol.6,no.6,pp.20-27,Dec.1999.
    [24]Shengli Zhou,Georgios B.Giannakis and Anna Scaglione,"Long Codes for Generalized FH-OFDMA Through Unknown Multipath Channels," IEEE Transactions on Communications,vol.49,no.4,pp721-733,April 2001.
    [25]Kostas Stamatiou and John G.Proakis,"A Performance Analysis of Coded Frequency-Hopped OFDMA," Proc.of IEEE WCNC,2005.
    [26]Vueetie Branka,Yuan Jinhong,Space Time Coding,New York,Wiley,2003.
    [27]Winters J.H.,"The Diversity Gain of Transmit Diversity in Wireless systems with Rayleigh Fading," Proc of IEEE ICC,pp.1121-1125,February 1994.
    [28]Rhee W.,Yu W.,Cioffi J.M.,"Utilizing Multiuser Diversity for MultiPle Antenna Systems," Proc of IEEE WCNC,Chicago,pp.420-425,Sep.2000.
    [29]R.Prasad and S.Hara,"Overview of multicarrier CDMA," IEEE Communications Magazine,pp.126-133,Dec.1997.
    [30]Yee N.,J-P.Linnartz and G.Fettweis,"Multi-Carrier CDMA in Indoor Wireless Radio Networks," Proc.Of IEEE PIMRC'93,pp.109-113,Sept.1993.
    [31]A.Chouly,A.Brajal and S.Jourdan,"Orthogonal Multicarrier Techniques applied to Direct Sequence Spread Spectrum CDMA System," Proc.of IEEE GLOBECOM'93,pp.1723-1728,Nov.1993.
    [1]C.Shannon,A mathematical theory of communication,Bell Labs Tech.J.,pp. 379-423,623-656,July and October 1948.
    [2]Paulraj Arogyaswami,Nabar Rohit and Gore Dhananjay,Introduction to Space-Time wireless communications,Cambridge University Press,2003.
    [3]G.Raleigh and J.Cioffi,"Spatio-temporal coding for wireless communication,"IEEE Trans.on Comm.,pp.357-366,March 1998.
    [4]E.Biglieri,J.Proakis and S.Shamai,"Fading channels:information-theoretic and communications aspects," IEEE Trans.Inf.Theory,pp.2619-2692,October 1998.
    [5]I.Telatar,"Capacity of multi-antenna Guassian channels," European Trans.Tel.,pp.585-595,November/December 1999.
    [6]Mohinder Jankiraman,Space-Time codes and MIMO Systems,Artech House Boston INC,2004.
    [7]Helmut Bolcskei,David Gesbert and Arogyaswami J.Paulraj,"On the Capacity of OFDM-Based Spatial Multiplexing Systems," IEEE Trans.on Commun.,vol.50,pp.225-234,February 2002.
    [8]Da-Shan Shiu,Gerard J.Foschini,Michael J.Gans and Joseph M.Kahn,"Fading Correlation and Its Effect on the Capacity of Multielement Antenna Systems," IEEE Trans.on Commun.,vol.48,pp.502-513,March 2000.
    [9]Andrea Goldsmith,Syed Ali Jafar,Nihar Jindal and Sriram Vishwanath,"Capacity Limits of MIMO Channels," IEEE J.Select.Areas Comm.,vol.21,pp.684-702,June 2003.
    [10]Chiani Marco,Moe Z.Win and Alberto Zanella,"On the capacity of spatially correlated MIMO Rayleigh-fading channel," IEEE Trans.on Inf.Theory,pp.2363-2371,October 2003.
    [11]L.J.Chmini,"Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing," IEEE Trans.on Commun.,vol.33,pp.665-675,July 1995.
    [12]J.Winters,"On the Capacity of Radio Communication Systems with Diversity in a Rayleigh Fading Environment," IEEE J.Select.Areas Commun.,vol.5,pp.871-878,January 2001.
    [13]Jun Wang,Shi-hua Zhu and Lei Wang,"On the Channel Capacity of MIMO-OFDM Systems," Proc.of IEEE ISCIT 2005,pp.1325-1328,October 2005.
    [14]A.J.Goldsmith and P.P.Varaiya,"Capacity of Fading Channels with Channel Side Information," IEEE Trans.Inf.Theory,vol.43,pp.1986-1992,Novenber 1997.
    [15]Branka Vucetic and Jinhong Yuan,Space-Time Coding,John Wiley & Sons,2003.
    [16]I.S.Gradshteyn and I.M.Ryzhik,Table of Integrals,Series and Products,New York,Academic Press,1980.
    [17]Richard van Nee and Ramjee Prasad,OFDM for Wireless Multimedia Communications,Artech House,Boston London,2000.
    [1]Branka Vucetic and Jinhong Yuan,Space-Time Coding,John Wiley & Sons,2003.
    [2]G.J.Foschni,"Layered Space-time Architecture for Wireless Communication in Fading Environments When Using Multi-element Antennas," Bell Labs Tech.J.,pp.41-59,1996.
    [3]J.Winters,"On the Capacity of Radio Communication Systems with Diversity in a Rayleigh Fading Environment," IEEE J.Select.Areas Commun.,vol.5,pp.871-878,January 2001.
    [4]Mohinder Jankiraman,Space-Time codes and MIMO Systems,Artech House,2004.
    [5]I.E.Telatar,"Capacity of multi-antenna gaussian channels," Eur.Trans.Telecommun.,vol.10,no.6,pp.585-596,Nov./Dec.1999.
    [6]J.A.C.Bingham,"Multicarrier Modulation for Data Transmission:an idea whose time has come," IEEE Commun.Mag,pp.5-14,May 1990.
    [7]L.J.Chmini,"Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing," IEEE Trans.on Commun.,vol.33,pp.665-675,July 1995.
    [8]Richard van Nee and Ramjee Prasad,OFDM for Wireless Multimedia Communications,Artech House,Boston London,2000.
    [9]P.xia,S.zhou,and G.Giannakis,"Adaptive MIMO-OFDM based on partial channel state inforamtion," IEEE Trans.On Signal Processing,vol.52,no.1,pp.203-213,Jan 2004.
    [10]H.Bolcskei,"MIMO-OFDM Wireless Systems:Basic,Perspectives,and Challenges," IEEE Trans.On Wireless Commun.,vol.52,no.1,pp.31-37,August 2006.
    [11]A.Pascual-Iserte,A.Perez-Neira,and M.Lagunas,"On Power Allocation Strategies for Maximum Singal to Noise and Interference Raio in an OFDM-MIMO system," IEEE Trans.On Wireless Commun.,vol.3,no.3,pp.808-820,May 2004.
    [12]Arogyaswami Paulraj,Rohit Nabar and Dhananjay Gore,Introduction to Space-Time Wireless Communications,Cambridge University Press,2003.
    [13]Leng Nana,Yang Shouyi,Lu Yanhui,Qi Lin,"Dynamic Spatial Subcarrier and Power Allocation for Multiuser MIMO-OFDM System," IEEE Proc.of WiCom 2007,pp.180-183,September 2007.
    [14]Li Guo,Yih-Fang Huang,"An Opportunistic Downlink Mimo-Ofdm Scheme,"IEEE Proc.of ICASSP 2006,May 2006.
    [15]R.Chemaly,K.B.Letaief,D.Zeghlache,"Adaptive resource allocation for multiuser MIMO/OFDM networks based on partial channel state information,"IEEE Proc.of GLOBECOM 2005,Dec.2005.
    [16]Li G.,Liu H.,"On the optimality of downlink OFDMA MIMO Systems," IEEE Proc.of ACSSC 2004,pp.324 -328,November 2004.
    [17]John Hyun Sung and John R.Barry,"Rate-Allocation Strategies for Closed-Loop MIMO-OFDM," IEEE Proc.of VTC 2003 Fall,pp.483-487,October 2003.
    [18]Chengkang Pan,Yueming Cai and Youyun Xu,"Adaptive subcarrier and power allocation for multiuser MIMO-OFDM systems," IEEE Proc.oflCC 2005,pp.2631-2635,May 2005.
    [19]Zhenping Hu,Guangxi Zhu,Yuan Xia and Gan Liu,"Adaptive subcarrier and bit allocation for multiuser MIMO-OFDM transmission," IEEE Proc.of VTC 2004,pp.779-783,May 2004.
    [20]Zhenping Hu,Guangxi Zhu,Yuan Xia and Gan Liu,"Multiuser subcarrier and bit allocation for MIMO-OFDM systems with perfect and partial channel information," IEEE Proc.of WCNC 2004,pp.1188-1193,March 2004.
    [21]Ya-Han Pan,Khaled Ben Letaief,and Zhigang Cao,"Dynamic Resource Allocation with Adaptive Beamforming for MIMO/OFDM Systems under Perfect and Imperfect CSI," IEEE Proc.of WCNC 2004,pp.93-97,May 2004.
    [22]Issam Toufik and Marios Kountouris,"Power Allocation and Feedback Reduction for MIMO-OFDMA Opportunistic Beamforming," IEEE Proc.of VTC 2006,pp.2568-2572,2006.
    [23]Ya-Han Pan,Khaled Ben Letaief,and Zhigang Cao,"Dynamic Spatial Subchannel Allocation with Adaptive Bemforming for MIMO/OFDM Systems," IEEE Trans.On Wireless Commum.,vol.3,no.6,pp.2097-2107,November 2004.
    [24]Jiboon Choi and Robert W.Heath,"Interpolation Based Transmit Beamforming for MIMO-OFDM With Limited Feedback," IEEE Trans.On Signal Processing,vol.53,no.11,pp.4125-4135,November 2005.
    [25]June Chul Roh and Bhaskar,"Transmit Beamforming in Multiple-Antenna Systems with Finite Rate Feedback:A VQ-based Approach," IEEE Trans.On Information Theory,vol.52,no.3,pp.1101-1112,March 2006.
    [26]Cheong Yui Wong,R.S.Cheng,K.B.Lataief and R.D.Murch,"Multiuser OFDM with adaptive subcarrier,bit,and power allocation," IEEE Journal on Selected Areas in Communications,vol.17,pp.1747-1758,Oct.1999.
    [27]Didem Kivanc,Guoqing Li,and Hui Liu,"Computationally Efficient Bandwidth Allocation and Power Control for OFDMA," IEEE Transactions on Wireless Communications,vol.2,pp.1150-1158,Nov.2003.
    [28]D.Hughes-Hartogs,"Ensemble modem structure for imperfect transmission media," U.S.Patents,Nos.2679227(July 1987),4731816(March 1988) and 4833796(May 1989)
    [1]IEEE 802.16e D5 Amendment to IEEE Standard for Local and Metropolitan Area Networks.
    [2]C.Cicconetti,L.Lenzini,placeE.Mingozzi,and C.Eklund,"Quality of service support in IEEE 802.16 networks," IEEE Network,vol.20,pp.50-55,April 2006.
    [3]A.Sayenko,O.Alanen,J.Karhula,and T.Hamaainen,"Ensuring the QoS Requirements in 802.16 Scheduling," Proc.of Int.Workshop Modeling Analysis and Simulation Wireless and Mobile Systems,Terromolinos,Spain,2006,pp.108-117.
    [4]A.Sayenko,O.Alanen,and T.Hamaainen,"Scheduling solution for the IEEE 802.16 base station," Int.J.Computer and Telecommunications Networking,vol.52,pp.96-115,Jan.2008.
    [5]A.Iera,A.Molinaro,S.Pizzi,and R.Calabria,"Channel-Aware Scheduling for QoS and Fairness Provisioning in IEEE 802.16/WiMAX Broadband Wireless Access Systems," IEEE Network,vol.21,pp.34-41,Oct.2007.
    [6]N.Liu,X.Li,C.Pei,and B.Yang,"Delay Character of a Novel Architecture for IEEE 802.16 Systems," Proc.of Int.Conf.Parallel and Distributed Computing,Applications and Technologies,Dalian,China,pp.293-296,2005.
    [7]A.L.Stolyar and K.Ramanan,"Largest Weighted Delay First Scheduling:Large Deviations and Optimality," Annals of Applied Probability,vol.11,pp.1-48,2001.
    [8]D.H.Kim and C.G.Kang,"Delay Threshold-based Priority Queueing Packet Scheduling for Integrated Services in Mobile Broadband Wireless Access System," Proc.of IEEE Int.Conf.High Performance Computing and Communications,Kemer-Antalya,Turkey,pp.305-314,2005.
    [9]J.M.Ku,S.K.Kim,S.H.Kim,S.Shin,J.H.Kim,and C.G.Kang,"Adaptive delay threshold-based priority queueing scheme for packet scheduling in mobile broadband wireless access system," Proc.of IEEE Wireless Communication and Networking Conf.,Las Vegas,NV,vol.2,pp.1142-1147,2006.
    [10]Y.Wang,S.Chan,M.Zukerman,and R.J.Harris,"Priority-Based fair Scheduling for Multimedia WiMAX Uplink Traffic," Proc.of IEEE Int.Conf.Communications,Beijing,China,pp.301-305,2008.
    [11]L.F.M.de Moraes and P.D.Jr.Maciel,"Analysis and evaluation of a new MAC protocol for broadband wireless access," Proc.of Int.Conf.Wireless Networks,Communications,and Mobile Computing,Kaanapali Beach Maui,Hawaii,vol.1,pp.107-112,2005.
    [12]W.Lilei and X.Huimin,"A new management strategy of service flow in IEEE 802.16 systems," Proc.of IEEE Conf.Industrial Electronics and Applications,Harbin,China,pp 1716-1719,2008.
    [13]D.Niyato and E.Hossain,"Queue-aware uplink bandwidth allocation for polling services in 802.16 broadband wireless networks," Proc.of IEEE Global Telecommunications Conf.,St.Louis,MO,vol.6,pp.5-9,2005.
    [14]J.Chen,W.Jiao and H.Wang,"A service flow management strategy for IEEE 802.16 broadband wireless access systems in TDD mode," Proc.of IEEE Int.Conf.Communications.,Seoul,Korea,vol.5,pp.3422-3426,2005.
    [15]A.K.F.Khattab and K.M.F.Elsayed,"Opportunistic scheduling of delay sensitive traffic in OFDMA-based wireless networks," Proc.of Int.Symp.World of Wireless Mobile and Multimedia Networks.,Buffalo,NY,pp.10-19, 2006,.
    [16]P.Bender,P.Black,M.Grob,R.Padovani,plateN.Sindhushayana,and A.Viterbi,"CDMA/HDR:A Bandwidth-Efficient High-Speed Wireless Data Service for Nomadic Users," IEEE Commun.Mag.,vol.38,pp.70-77,Jul.2000.
    [17]H.Kim and Y.Han,"A proportional fair scheduling for multicarrier transmission systems," IEEE Commun.Lett.,vol.9,pp.210-212,Mar.2005.
    [18]F.Hou,P.Ho,X.Shen,and A.Chen,"A Novel QoS Scheduling Scheme in IEEE 802.16 Networks," Proc.of IEEE Wireless Communication and Networking Conf.,Hong Kong,2007,pp.2457-2462.
    [19]S.Shakkottai,R.Srikant,and A.Stolyar,"Pathwise Optimality and State Space Collapse for the Exponential Rule," Proc.of IEEE Int.Symp.Information Theory,pp.379,2002.
    [20]V.Singh and V.Sharma,"Efficient and Fair Scheduling of Uplink and Downlink in IEEE 802.16 OFDMA Networks," Proc.of IEEE Wireless Communication and Networking Conf.,Las Vegas,NV,vol.2,pp.984-990,2006.
    [21]Y.J.Zhang and S.C.Liew,"Link-adaptive largest-weighted-throughput packet scheduling for real-time traffics in wireless OFDM networks," Proc.of IEEE Gobelcom.,vol.5,pp.5-9,2005.
    [22]M.Andrews,K.Kumaran,K.Ramanan,A.Stolyar,P.Whiting,and R.Vijayakumar,"Providing quality of service over a shared wireless link," IEEE Commun.Mag.,vol.39,pp.150-154,Feb.2001.
    [23]P.W.C.Chan,E.S.Lo,Lan,V.K.N.Lau,R.S.Cheng,K.B,Letaief,R.D.Murch and W.H.Mow,"Performance Comparison of Downlink Multiuser MIMO-OFDMA and MIMO-MC-CDMA with Transmit Side Information,"IEEE Trans.on Wireless Commun.,vol.19,pp.2193-2203,June 2007.
    [24]S.W.H.David,L.N.K.Vincent and H.L.Wong,"Cross-Layer Design for OFDMA Wireless Systems with Heterogeneous Delay Requirements," IEEE Trans.on Wireless Commun.,vol.6,no.8,pp.2872-2880,August 2007.
    [25]F.Zhou,"1xEV-DV evaluation methodology(Rev.26)," WG5 Evaluation AHG,May 2001.
    [1]中华人民共和国信息产业部网站,http://www.mii.gov.cn
    [2]Vueetie Branka,Yuan Jinhong," Space Time Coding," New York,Wiley,2003.
    [3]A.Narula,M.J.Lopez,M.D.Trott,and G.W.Wornell,"Efficient use of side information in multiple-antenna data transmission over fading channels," IEEE J.Sel.Areas Commun.,vol.16,no.8,pp.1423-1436,Oct.1998.
    [4]D.J.Love and R.W.Heath Jr.,"Equal gain transmission in multi-input multi-output wireless systems," IEEE Trans.on Commun.,vol.51,no.7,pp.1102-1110,Jul.2003.
    [5]D.J.Love,R.W.Heath Jr.,and T.Strohmer,"Grassmannian bearnforming for multiple-input multiple-output wireless systems," IEEE Trans.on Inf.Theory,vol.49,no.10,pp.2735-2747,Oct.2003.
    [6]K.K.Mukkavilli,A.Sabharwal,E.Erkip,and B.Aazhang,"On beamforming with finite rate feedback in multiple-antenna systems," IEEE Trans.on Inf.Theory,vol.49,no.10,pp.2562-2579,Oct.2003.
    [7]Ying Jun Zhang,Letaief K.B.,"An efficient resource-allocation scheme for spatial multiuser access in MIMO/OFDM systems," IEEE Trans.on Commun.,vol.53,Issue 1,pp.107-116,Jan 2005.
    [8]Ying Jun Zhang,Letaief K.B.,"Optimizing power and resource management for multiuser MIMO/OFDM systems," Proc.of IEEE Gobelcom,vol.1,pp.179-183,Dec 2003.
    [9]Lei Li,Zhisheng Niu,"A Multi-Dimensional Radio Resource Scheduling Scheme for MIMO-OFDM Systems with Channel Dependent Parallel Weighted Fair Queueing(CDPWFQ)," Proc.of IEEE Gobelcom,pp.2367-2371,2004.
    [10]Zhenping Hu,Guangxi Zhu,Yuan Xia,Gan Liu,"Adaptive subcarrier and bit allocation for multiuser MIMO-OFDM transmission," Proc.of IEEE VTC,pp.779-783,2004.
    [11]Zhenping Hu,Guangxi Zhu,Yuan Xia,Gan Liu,"Multiuser subcarrier and bit allocation for MIMO-OFDM systems with perfect and partial channel information," Proc.of IEEE WCNC,pp.1188-1193,2004.
    [12]Francesc Rey,Meritxell Lamarca and Gregori Vazquez,"Robust Power Allocation Algorithms for MIMO OFDM Systems with Imperfect CSI," IEEE Transactions on Signal Processing,vol.53,No.3,pp.1070-1085,March 2005.
    [13]J.Jiang,R.M.Buehrer,and W.H.Tranter,"Multi-antenna downlink data transmission with precoding and scheduling," to be submitted to IEEE Trans.Vehicular Tech.,July 2004.
    [14]J.Jiang,R.M.Buehrer,and W.H.Tranter,"Antenna diversity in multiuser data networks," IEEE Trans.on Commun.,vol.52,pp.490-497,Mar 2004.
    [15]J.Jiang,R.M.Buehrer,and W.H.Tranter,"High-speed downlink packet transmission with spatial multiplexing and scheduling," Proc.of IEEE WCNC,Mar 2004.
    [16]Simone Redana,Matthias Lott,and Antonio Capone,"Performance Evaluation of Point-to-Multi-Point(PMP) and Mesh Air-Interface in IEEE Standard 802.16a," IEEE,pp.3186-3190,2004.
    [17]Siamak Naghian,Jouni Tervonen,"Seme-Infrastructured Mobile Ad-Hoc Mesh Networking," Proc.of IEEE PIMRC,pp.1069-1073,2003.
    [18]Siamak Naghian,"Mesh VS.Point-to-Multipoint Topology:A Coverage and Spectrum Efficiency Comparison," IEEE,pp.1048-1051,2004.
    [19]D.Lee,C.Xu,U.Mayekar,and M.Mohile,"Frequency Reuse Factor VS.Pathloss Exponent and Sectorization," IEEE,pp.109-112,1997.
    [20]Jun Xiang,"A Novel Two Site Frequency Reuse Plan," IEEE,pp.441-444,1996.
    [21]K.B.Letaief,Y.J.Zhang,"Dynamic Multi-user resource allocation and adaptation for wireless systems," IEEE Trans.on Wireless Commun.,pp.38-47,Aug 2006.
    [22]A.K.F.Khattab and K.M.F.Elsayed,"Opportunistic scheduling of delay sensitive traffic in OFDMA-based wireless networks," Proc.Int.Symp.World of Wireless Mobile and Multimedia Networks,pp.10-19,2006.
    [23]Antoniou Josephina,Pitsillides Andreas,"4G converged environment:modeling network selection as a game," Mobile and Wireless Communications Summit,pp.1-5,July 2007.
    [24]D.Niyato and E.Hossain,"A cooperative game framework for bandwidth allocation in 4G heterogeneous wireless networks," Proc.of IEEE ICC,pp.4357-4362,June 2006.
    [25]D.Niyato and E.Hossain,"A noncooperative gametheoretic framework for radio resource management in 4G heterogeneous wireless access networks,"IEEE Transactions on Mobile Computing,pp.322-345,2008.
    [26]A.Nosratinia,T.E.Hunter and A.Hedayat,"Cooperative Communication in Wireless Networks," IEEE Communication Magazine,pp.70-84,2004.
    [27]T.E.Hunter,S.Sanayei and A.Nosratinia,"Outage Analysis of Coded Cooperation," IEEE Trans.on Inform.Theory,pp.375-391,2006.
    [28]T.E.Hunter,A.Nosratinia,"Diversity through Coded Cooperation," IEEE Trans on Inform Theory,pp.283-289,2006.
    [29]Gong Fengkui,Han Chunlei,Wang Yong,et al,"Design and Analysis of a CC Scheme with High order Constellations over Slow fading Rayleigh Channels,"Journal of Xidian University,pp.664-667,2008.
    [30]V.Mahinthan,J.W.Mark,"A Simple Cooperative Diversity Scheme Based on Orthogonal Signaling," Proc.of IEEE WCNC,pp.41-45,2005.
    [31]V.Mahinthan,J.W.Mark,X.S.Shen,"A Cooperative Diversity Scheme Based on Quadrature Signaling," IEEE Trans on Wireless Communication,pp.,2007,.
    [32]V.Marojevic,X.Reves and A.Gelonch,"Cooperative Resource Management in Cognitive Radio," Proc.of IEEE ICC,pp.5939-5944,June 2007.
    [33]Yonghong Zhang and C.Leung,"Resource allocation for non-real-time services in OFDM-based cognitive radio systems," IEEE Communications Letters,pp.16-18,January 2009.
    [34]Yueling Che,Jie Chen,Wanbin Tang and Shaoqian Li,"A Two-Step Channel and Power Allocation Scheme in Centralized Cognitive Networks Based on Fairness," Proc.of IEEE VTC,pp.1589-1593,May 2008.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700