共查询到20条相似文献,搜索用时 15 毫秒
1.
Liang Yang 《Wireless Personal Communications》2007,43(4):1751-1754
In this letter, taking into account realistic propagation environments in the presence of log- normal shadowing, we analyze
the outage performance of orthogonal space-time block coding (OSTBC) for an arbitrary finite number of transmit and receive
antennas. An approximate expression for the outage probability of OSTBC over Rayleigh-fading multiple-input multiple-output
(MIMO) channels with shadowing is presented. Finally we give some numerical results to verify our analysis. 相似文献
2.
Arvind Dhaka Siddhartha Chauhan Vidyacharan Bhaskar 《Wireless Personal Communications》2018,100(3):863-875
In this paper, the expressions for level crossing rate and average fade duration of two-branch selection combining are derived using the proposed matrix partitioning based method for a space-diversity system using a two-branch horizontal linear antenna array at the mobile station. It has been observed that when the antennas are perpendicular to the direction of the vehicle motion, the average fade duration is not very much dependent on the antenna spacing and is almost identical to that for independent fading except for very small antenna spacing. On the other hand, when the antennas are parallel to the direction of the vehicle motion, the level crossing rate can be reduced below the value obtained for independent fading, although the average fade duration deteriorates, especially for small antenna spacing. Numerical results are presented and compared with the existing characteristic function based methods including Gaussian fluctuation effects. 相似文献
3.
《Vehicular Technology, IEEE Transactions on》2005,54(4):1259-1265
In this paper, study of the second order statistics of the Nakagami-Hoyt fading channel model (Nakagami-$q$ model) is considered. Expressions for the level crossing rate (LCR) as well as the average duration of fades (ADF) are derived. It is shown that the obtained analytical quantities best fit the corresponding measurement data for an equivalent mobile satellite channel in the case of an environment with heavy shadowing. This leads to the conclusion that the Nakagami-$q$ model is applicable to realistic mobile communication channels. A simple and efficient deterministic simulation model based on the Rice's sum of sinusoids, which enables the emulation of the fading envelope of the Nakagami-$q$ model with the desired statistics, is also described. A very good agreement is obtained between the simulated, analytical, and experimental statistics. 相似文献
4.
《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(11):4887-4907
5.
WANG Jun-xuan~ RAO Wen-yuan~ LI Dao-ben~. Xi''''an Institute of Posts Telecommunications Xi''''an P.R. China . Jiangxi University of Finance Economics Nanchang P.R. China . Beijing University of Posts Telecommunications Beijing P.R. China 《中国邮电高校学报(英文版)》2005,12(4)
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… 相似文献
6.
Taricco G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(8):3490-3504
The asymptotic probability distribution of the mutual information of a separately correlated Rician fading multiple-input multiple-output (MIMO) channel is addressed. The mean and variance of the mutual information are derived when the number of transmit and receive antennas grows asymptotically large while their ratio approaches a finite constant. This derivation is based on the replica method, widely used in theoretical physics and, more recently, in the analysis of communication systems (code-division multiple access (CDMA) and MIMO). Though the replica method allows to analyze complex systems in a comparatively simple way, some authors pointed out that its assumptions are not always rigorous. It is shown that the mutual information converges asymptotically to a Gaussian distribution under mild technical conditions, which are tantamount to assuming that the spatial correlation structure has no asymptotically dominant eigenmodes. The accuracy of the asymptotic approach is assessed by numerical results. It is shown that the approximation is very accurate in a wide range of system settings, even when the number of transmit and receive antennas is as small as a few units. 相似文献
7.
本文全面地分析了在Nakagami-m衰落信道下具有"匙孔"(keyhole)效应时正交块空时编码(STBCs)的多输入多输出 (MIMO)系统的容量以及误比特率(BER)性能,导出了该系统环境下平均容量的紧下边界值,同时得出了系统中断概率的具体表达式及其误码率的近似值.在此基础上分析了Keyhole MIMO信道下的天线选择问题.最后进行了仿真,其结果与理论分析一致.研究表明,在Keyhole MIMO信道中,采用天线选择仍然能够获得与全复杂系统相同的分集增益. 相似文献
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10.
On the Secrecy Capacity of Fading Channels 总被引:1,自引:0,他引:1
《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(10):4687-4698
11.
在理想多输入多输出(MIMO)系统容量的基础上,推导了衰落信道空间相关性对MIMO系统容量的影响,并通过MATLAB仿真进行了验证,最后给出了结论。 相似文献
12.
A new exact explicit expression is derived for the ergodic capacity of maximal ratio combining (MRC) schemes over arbitrarily correlated Rician fading channels. This is used to study the effects of channel correlation on the ergodic capacity. Numerical results reveal that both the phase and the magnitude of correlation have an impact on the ergodic capacity of Rician fading channels. This is in contrast to correlated Rayleigh fading, where the phase of the correlation has no effect on the ergodic capacity. It is also observed that negatively correlated branches in Rician fading may lead to an increase in ergodic capacity beyond that obtained by uncorrelated branches. 相似文献
13.
一种分布式多入多出(MIMO)信道的容量研究 总被引:10,自引:1,他引:10
分布式MIMO系统结合了点对点MIMO信道与分布式天线系统两者的特点,能改善链路的质量,提高覆盖面积。本文提出了一种包含路径损耗、阴影衰落与小尺度衰落的分布式MIMO信道模型,分析推导了采用该模型时的分布式MIMO信道容量。通过计算机仿真,研究分析了阴影衰落、Rice信道因子K等因素对分布式MIMO上行信道容量的影响,得出了分布式MIMO信道容量空间分布的特点。 相似文献
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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 总被引:5,自引:0,他引:5
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。 相似文献
16.
This paper characterizes the eigenvalue distributions of full-rank Hermitian matrices generated from a set of independent (non)zero-mean proper complex Gaussian random vectors with a scaled-identity covariance matrix. More specifically, the joint and marginal cumulative distribution function (CDF) of any subset of unordered eigenvalues of the so-called complex (non)central Wishart matrices, as well as new simple and tractable expressions for their joint probability density function (PDF), are derived in terms of a finite sum of determinants. As corollaries to these new results, explicit expressions for the statistics of the smallest and largest eigenvalues, of (non)central Wishart matrices, can be easily obtained. Moreover, capitalizing on the foregoing distributions, it becomes possible to evaluate exactly the mean, variance, and other higher order statistics such as the skewness and kurtosis of the random channel capacity, in the case of uncorrelated multiple-input multiple-output (MIMO) Ricean and Rayleigh fading channels. Doing so bridges the gap between Telatar's initial approach for evaluating the average MIMO channel capacity (Telatar, 1999), and the subsequently widely adopted moment generating function (MGF) approach, thereby setting the basis for a PDF-based framework for characterizing the capacity statistics of MIMO Ricean and Rayleigh fading channels. 相似文献
17.
Moustakas A.L. Simon S.H. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(11):3887-3903
The use of multiple-antenna arrays can dramatically increase the throughput of wireless communication systems. Thus, it is important to characterize the statistics of the mutual information for realistic correlated channels. Here, a mathematical approach is presented, using the method of replicas, that provides analytic expressions not only for the average, but also for the higher moments of the distribution of the mutual information for the most general zero-mean Gaussian multiple-input multiple-output (MIMO) channels when the channel is known at the receiver. These channels include multitap delay paths, and channels with covariance matrices that cannot be written as a Kronecker product, such as general dual-polarized correlated antenna arrays. This approach is formally valid for large antenna numbers, in which case all cumulant moments of the distribution, other than the first two, scale to zero. In addition, it is shown that the replica-symmetric result is valid if the variance of the mutual information is positive and finite. In this case, it is shown that the distribution of the mutual information tends to a Gaussian, which enables the calculation of the outage capacity. These results are quite accurate even for few antennas, which makes this approach applicable to realistic situations. 相似文献
18.
The Performance of Multiuser Diversity Scheduling for MIMO Channels With Spatially Correlated Fading
《Communications, IEEE Transactions on》2006,54(9):1533-1535
We study a cellular network with one multiantenna base station and a number of multiantenna users. Correlated fading may exist at the base station or at the users, or at both sides. With time-varying fading, multiuser diversity is exploited by always allowing the base station to transmit to the user with the best channel. For this network, we find that if the number of transmitter antennas and the number of receiver antennas grow with a fixed ratio, the multiuser diversity gain will approximately remain constant. 相似文献
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Gursoy M.C. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(10):4543-4567
In this paper, the capacity and energy efficiency of training-based communication schemes employed for transmission over a priori unknown Rayleigh block-fading channels are studied. Initially, the case in which the product of the estimate error and transmitted signal is assumed to be Gaussian noise is considered. In this case, it is shown that bit energy requirements grow without bound as the signal-to-noise ratio (SNR) goes to zero, and the minimum bit energy is achieved at a nonzero SNR value below which one should not operate. The effect of the block length on both the minimum bit energy and the SNR value at which the minimum is achieved is investigated. Flash training and transmission schemes are analyzed and shown to improve the energy efficiency in the low-SNR regime. In the second part of this paper, the capacity and energy efficiency of training-based schemes are investigated when the channel input vector in each coherence block is subject to peak power constraints. The capacity-achieving input structure is characterized and the magnitude distribution of the optimal input is shown to be discrete with a finite number of mass points. The capacity, bit energy requirements, and optimal resource allocation strategies are obtained through numerical analysis. The improvements in energy efficiency when on-off keying (OOK) with fixed peak power and vanishing duty cycle is employed are studied. 相似文献