频率选择性衰落环境中MIMO系统信道容量研究

提出了一种频率选择性环境中多输入多输出系统信道容量的分析方法.该方法基于接收均匀圆阵构建了蕴含天线间距、散射角大小和多径数等模型物理参数的衰落空间相关模型。分析了MIMO OFDM系统信道衰落的统计特性。在此基础上利用Wishart分布的性质详细推导了任意天线数的MIMO OFDM系统的信道容量及其上下限。该方法回避了已有方法需要求取信道衰落相关特征值概率密度函数的问题，降低了运算量；并且可以有效地分析在频率选择性环境中模型物理参数对信道容量的影响。仿真结果表明，随着天线间距的增大，系统的平均信道容量也逐渐增大；但当天线间距增大到一定程度后,信道容量变化不明显，散射角越大，信道容量的增长速率越快，当接收信噪比较高时,平均信道容量的上下限接近于其实际值。     

平坦衰落环境中多输入多输出系统衰落相关与信道容量研究

为分析模型物理参数和天线排列方式对多输入多输出系统信道容量的影响,提出了一种平坦衰落环境中信道容量的研究方法。该方法基于接收均匀圆阵和均匀线阵分别构建了蕴含模型物理参数的相关矩阵,并利用Wishart分布的性质推导了信道容量上下限。该方法回避了求取衰落相关矩阵特征值的概率密度函数,降低了运算量;可被推广到多天线-频分复用系统。仿真结果表明,天线间距较小时,采用均匀圆阵比均匀线阵的系统信道容量要高;天线间距增大到一定程度后,系统信道容量达到饱和。散射角越大,信道容量的增长速率越快且采用均匀线阵比均匀圆阵系统的信道容量高。接收信噪比较大时,平均信道容量上下限基本接近其实际值。     

在相关信道下MIMO-OFDM信道容量的分析

利用中心Wishart矩阵的性质得到相关信道下的多输入/输出正交频分复用系统(Multiple Input Multiple out-put;Orthogonal Frequency Division Multiplexing,MIMO OFDM)的信道容量的上下界限,同时分析天线相关对信道容量的影响。假设接收端有完全的信道状态信息(CSI),而发射端没有任何的CSI的情况下得到了信道容量的上下界限,通过仿真说明得到的界限是紧凑的,同时说明信道相关如何降低信道容量。     

MIMO—OFDM加性信道容量仿真实现

OFDM技术能将频率选择性信道转变为平坦衰落信道,而MIMO技术在平坦衰落信道上可显著提高信道容量,从而大幅度提高频谱效率。本文分析了MIMO—OFDM系统中加性高斯自噪声（AWGN）信道的信道容量。     

衰落信道下MIMO-OFDM系统信道容量分析

针对以往文献的不足,该文重新推导了衰落信道下MIMO-OFDM系统信道容量公式,分析了子载波数目、时延扩展、角度扩展以及天线间距等因素对信道容量的影响。理论分析和仿真结果符合MIMO-OFDM信道容量特征。     

多天线系统及其在OFDM系统中的应用

利用配置多个天线实现高速可靠的通信是当今无线通信领域研究的热点之一。本文介绍了具有多个天线系统的几种不同构成方式，从系统误码率和频带利用率两个方面讨论了不同构成方式对系统的改善。同时，对多天线技术应用于正交频分复用(OFDM)系统的性能进行了分析，并给出了频率选择性瑞利衰落信道中最优译码算法下的系统性能比较。仿真结果表明，多天线OFDM系统既保持了OFDM抗频率选择性衰落的特点，又能够改善系统的误码率性能，提高频带利用率。     

多径衰落下多天线CDMA系统信道容量研究

该文对准静态Rayleigh衰落下MIMO-CDMA系统信道容量进行了研究,分析了扩频码为Walsh函数,基于多码检测的极大似然检测器(MLD)和解相关检测器的性能,并和MMSE多用户检测器(MUD)进行了比较;分析了对不同检测器在一定的信噪比下系统天线数目和信道容量的关系。仿真结果表明：在相同的情况下,基于Walsh码CDMA系统容量按MUD、干扰方差已知的MLD,干扰方差未知的MLD和解相关检测器递减,并且后面的3种检测器在大信噪比的时候均有渐进的平台效应;在信噪比较大且一定时,CDMA系统信道容量与天线数目呈线性关系。     

光多输入多输出系统信道容量的研究

提出了一种发射端不同偏置入射、接收端由多段检测器(MSD)构成检测器阵列的多模光纤多输入多输出(MIMO)系统.通过对MIMO信道矩阵的计算,研究了这种系统的信道容量随激光器和MSD的数目、距离、光束宽度和接收信噪比(SNR)等参数的变化情况.结果表明:光MIMO信道容量随激光器和MSD数目的增加而线性增加,增加入射光斑的尺寸会使信道容量增加的斜率变大并逐渐趋于饱和;入射光斑间的距离和MSD的构成对MIMO信道容量也有较大影响,尤其是当激光器和MSD数目较大时,需要足够大的距离才能提供信道响应在空间的差异性;对于模式足够丰富的N×N的MIMO系统,SNR每增加3 dB,信道容量会增加Nbps/Hz.     

相关衰落下多天线 LS-CDMA信道容量

对相关多径信道下不同扩频地址码的多天线CDMA系统的信道容量进行了研究,在研究中分别采用了在多码检测和多用户检测联合检测算法.在多码检测的情况下,李道本教授发明的LS码多天线CDMA系统比Walsh码和Gold码的多天线系统有更大的系统容量,后两者在大的信噪比(20dB)时候均有平台效应;在采用多用户检测时它们的容量几乎相同.由于具有零相关窗特性,对于LS码而言这两种方法是等效的.当发射天线数目等于接收天线数目时,系统的容量和天线数目呈线性关系.     

B3G无线通信中MIMO技术现状

MIMO作为下一代无线通信的主要技术之一，能够突破无线频率资源限制，大幅度提高无线通信系统的频谱效率，迅速成为当今无线通信研究的热点。文中主要从信道容量理论、系统结构、编码现状、译码现状和发展趋势几方面对M1MO系统作了分析，最后通过仿真进行了验证。     

室内MIMO无线信道模型和信道容量研究

本文从工程的实际出发,首先提出一种修正的室内MIMO无线信道模型,该模型有效地修正先前室内MIMO无线信道模型的不足,具有明显吻合室内实际通信环境的特点,然后分析天线方向性以及天线单元间的互耦对室内MIMO无线信道容量的影响.数值模拟验证了这种影响,并得到在一定条件下互耦导致的天线方向图畸变产生角度分集,提高信道容量,互耦对空域相关性无影响的条件以及室内丰富的多径使天线方向性对信道容量的影响不明显等结论.最后,实验也证实理论分析.     

MIMO信道的空间相关特性及信道容量分析

该文针对非频率选择性MIMO衰落信道,建立接收阵列的三维(3D)信道模型,推导出关于空间距离矢量的空间相关函数表达式,并且仿真分析了空间距离矢量对电压相关系数的影响,分析了电压相关系数对信道容量的影响,仿真结果说明电压相关系数与信道容量呈反比关系.     

适合频率选择性MIMO信道的FIR预编码器

改善频率选择性多输入多输出(MIMO)系统的信道容量,具有重要的理论和现实意义。基于最大信道容量准则,提出一种适合MIMO频率选择性衰落信道的预编码新方法。该方法将预编码器建模为一个有限冲击响应(FIR)滤波器,利用秩松弛将原非凸优化问题转换成为半定规划(SDP)问题,并结合特征值分解设计预编码器。仿真实验结果和分析表明,相对于扩展均匀信道分解(EUCD)等其它现有算法,该算法仅需较少的滤波器阶数即可显著提升系统的信道容量,具有较低的实现复杂度。     

MIMO系统信道容量研究

针对单用户MIMO系统信道的容量特性展开研究。首先详细推导了无衰落信道下信道容量表达式,然后重点分析了瑞利衰落信道下,接收端已知信道状态信息,发射端已知信道状态分布时的容量特性。最后分别针对瑞利衰落信道下,采用发射分集、接收分集以及BLAST传输结构的系统容量进行仿真。仿真结果表明:给定发射功率,独立的瑞利衰落信道条件下,MIMO系统容量随最小天线数目的增加而线性增加,极大地提高了系统容量。     

Capacity of MI MO LAS-CDMA System Under Correlating Multi-Path Fading Channels

1IntroductionMI MOtechnology has emerged as a key method toachieve high spectral and power efficiency in wirelesscommunications .By the work of E. Telatar and Fosi-chini[1 ~6]et al .,the capacity of aMtransmite anten-nas andNreceive antennas systemcan be min( M,N)ti mes that of a single antenna system,that is to say ca-pacity canincreaselinealy with minumof the number ofantennas at transmiter and receiver .In order to encounter multi-paths fading,capacity oftraditional BLAST-CDMAis res…     

不同衰落下的并行信道建模与容量分析

无线信道的分析与建模是无线通信研究的基础的工作,信号在传输过程中会受到不同衰落环境的影响,例如频率选择性衰落、时间选择性衰落和空间选择性衰落。为了分析无线传播环境在这三种衰落条件下的信道特性,分别对三种衰落信道进行并行信道建模,在此基础上将注水原理分别应用于这三种衰落信道中,即分别在频率、时间和空间上进行最佳功率分配,只对信道状况良好的子信道分配功率,最后得到不同衰落信道下的信道容量。     

MIMO Channel Characterization for Short Range Fixed Wireless Propagation Environments

This paper reports results from wideband MIMO measurements performed in short range fixed wireless environments at 5.2 GHz. The objective is to provide MIMO channel characterization results for the measured environments and contribute to the limited available similar studies. Two kinds of propagation scenarios are investigated, rooftop to rooftop and street to rooftop, at three different sites always under LOS propagation conditions. The analysis of measurement data is performed in the context of non physical modeling, providing insight into the statistics of the measured channels. In particular, the slow time varying nature of the channel is studied and the narrow Doppler spectrum shape is approximated. Furthermore, frequency correlation results are obtained and the typical delay dispersion measures are extracted. Then, the antenna correlation is studied and the error of the Kronecker product approximation is evaluated. Finally, capacity results are provided and the channel measurements are characterized in terms of spatial multiplexing quality and multipath richness through condition number analysis. Nikolaos D. Skentos received his Diploma in Electrical and Computer Engineering from the National Technical University of Athens (NTUA), Greece in October 2000. Since January 2001 he has been a research associate at the Mobile Radio Communications Laboratory at the NTUA, and he is currently working towards the Ph.D. degree. His research interests include channel measurements, MIMO channel characterization, MIMO algorithms and space time processing. He has been active in the IST STINGRAY project, the COST 273 Action and the ACE Network of Excellence. He is also a member of the National Technical Chamber of Greece since 2001. Athanasios G. Kanatas received the Diploma in Electrical Engineering from the National Technical University of Athens, Greece, in 1991, the M.Sc. degree in Satellite Communication Engineering from the University of Surrey, Surrey, UK in 1992, and the Ph.D. degree in Mobile Satellite Communications from the National Technical University of Athens, Greece in February 1997. From 1993 to 1994 he was with National Documentation Center of National Research Institute. In 1995 he joined SPACETEC Ltd. where he was Technical Project Manager for VISA/EMEA VSAT Project in Greece. In 1996 he joined the Mobile Radio Communications Laboratory as a research associate. From 1999 to 2002 he was with the Institute of Communication & Computer Systems. In 2000 he became a member of the Board of Directors of OTESAT S.A. He is an Assistant Professor in the Department of Technology Education and Digital Systems at University of Piraeus. His current research interests include channel characterization and estimation, simulation and modeling for mobile, mobile satellite, and future wireless communication systems. He has been a Senior Member of IEEE since 2002, and is also a member of the Technical Chamber of Greece. In 1999 he was elected Chairman of the Communications Society of the Greek IEEE Section. Panagiotis I. Dallas was born 1967 in Thessaloniki, Greece. He obtained his diploma and Ph.D. degree from the Electrical and Computer Engineering Department of Aristotle University of Thessaloniki, Greece, in 1990 and 1997, respectively. Since 1998 he joined with INTRACOM where he currently is Section Manager of Advanced Communications Technologies branch of Emerging Technologies & Markets department, leading the next generation of broadband wireless access systems for internal and EU projects. He runs the relevant standardization activities (IEEE 802.16 and ETSI/BRAN HIPERMAN) in INTRACOM and he represents the company in WiMAX forum. Finally, he has over 30 publications in international journals and conferences. Philip Constantinou received the Diploma in Physics from the National University of Athens in 1972, the Master of Applied Science in Electrical Engineering from the University of Ottawa, Ontario, Canada in 1976, and the Ph.D. degree in Electrical Engineering in 1983 from Carleton University, Ottawa, Ontario, Canada. From 1976 to 1979 he was with Telesat Canada as a Communications System Engineer. In 1980 he joined the Ministry of Communications in Ottawa, Canada where he was engaged in the area of Mobile Communication. From 1984 to 1989 he was with the National Research Center Demokritos in Athens, Greece where he was involved in several research projects in the area of Mobile Communications. In 1989 he joined the National Technical University of Athens where he is currently a Professor and Director of the Mobile Radio Communications Laboratory. His current research interests include Personal Communications, Mobile Satellite Communications, and Interference Problems on Digital Communications Systems.