Macrodiversity and Microdiversity in Correlated Shadowed Fading Channels

Outage probabilities in shadowed fading channels are evaluated when macrodiversity and microdiversity techniques are implemented. The existence of correlation at the micro and macro levels is taken into account for the computation of outage probabilities. By modeling shadowing using a gamma probability density function, it is shown that an analytical expression for the outage can be expressed as the product of marginal outages summed with weighting factors that depend on the correlation coefficients at the macro level, assuming a maximal ratio combining at the micro level and selection combining (SC) diversity at the macro level. Results demonstrate the potential use of the approach in the analyses of wireless systems in shadowed fading channels.      

相关阴影Rician信道上广义矩形MQAM的性能

本文使用矩生成函数方法推导了相关视距(LOS)分量和独立散射分量条件下的多输入多输出阴影Rician衰落信道上采用正交空时分组编码(OSTBC)的广义矩形M进制正交幅度调制(MQAM)的平均误符号率(SEP)的精确闭合表达式.利用该表达式可计算信道衰落参数以及天线间的相关性对广义矩形MQAM平均SEP性能的影响.数值计算结果阐明,天线间的相关性恶化了广义矩形MQAM的平均SEP性能,广义矩形MQAM的平均SEP性能随着信道衰落参数的增大而得到改善.     

Second‐Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma‐Shadowed Rician Fading Channels

In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels is considered. Exact and rapidly converging infinite‐series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.     

Effect of Microdiversity and Macrodiversity on Average Bit Error Probability in Gamma‐Shadowed Rician Fading Channels

In this letter, we analyze the error performance of a mobile communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels for a binary differential phase‐shift keying modulation scheme. Analytical expressions for the probability density function (PDF) and moment‐generating function (MGF) are derived. The average bit error probability can be calculated by averaging the conditional bit error probability over the PDF or using the MGF‐based approach. Numerical results are graphically presented to show the effects of macrodiversity, correlation, number of diversity branches, and severity of both fading and shadowing.     

相关衰落信道采用MRC接收的MQAM性能分析

利用Q(x)和Q2(x)的另一种表达式及衰落信道上数字信号传输的归一化性能研究的结果,通过一种一般性方法分析了两种实用天线设置时相关衰落信道下采用MRC接收的MQAM的性能,得到误码率的解析表达式。比较了相关瑞利和赖斯衰落信道的信噪比损失情况。结论对多天线MQAM系统在性能和空间范围之间如何采取折衷有着重要的指导作用。     

On Physical Layer Security of Double Shadowed Rician Fading Channels

Wireless Personal Communications - With the proliferation of fifth-generation (5G) mobile communication wireless networks, the investigation into the performance of physical layer secrecy is...     

Capacity of MRC on Correlated Rician Fading Channels

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.     

采用分集接收的MQAM在Rician信道上的性能分析

 M-QAM是一种频谱利用率较高的调制方式,但是在多径环境下其性能的恶化限制了它在无线通信中的应用.本文结合Rician衰落特性,提出了采用最大比合并和选择式合并以有效改善M-QAM系统性能的方法.这种方法在实际中有着广泛的应用前景.     

采用分集接收的MQAM Rician信道上的性能分析

M-QAM是一种频谱利用率较高的调制方式,但是在多径环境下其性能的恶化限制了它在无线通信中的应用。本文结合Rician衰落特性,提出了采用最大比合并和选择式合并以有效改善M-QAM系统性能的方法。这种方法在实际中有着广泛的应用前景。     

Performance Analysis of Diversity Combining Algorithms in Shadowed Fading Channels

A compound fading model incorporating short term fading and shadowing proposed recently is used to analyze the performance of wireless systems employing microscopic diversity to mitigate the effects of flat fading. This model can account for the presence of different levels of fading and shadowing and provide an analytical solution for the probability density function of the signal-to-noise ratio. Using that model, the performances of MRC and SC diversity combining algorithms were studied. The amount fading (AF) following diversity implementation was calculated and it is seen that the decline in the amount of fading is bound by the level of shadowing present, with the MRC providing a larger decrease in the amount of fading than the SC algorithm. The effect on the error rates was studied using the example of the coherent BPSK modem. Results show that the performances of wireless systems can be analyzed using the compound model for the shadowed fading channels. P.M. Shankar received his M. Sc (1972) in Physics from Kerala University, India, M. Tech (1975) in Applied Optics and Ph. D. in Electrical Engineering (1980) from Indian Institute of Technology, Delhi, India. He was a visiting scholar at the School of Electrical Engineering, University of Sydney, Australia, from 1981 to 1982. He joined Drexel University in 1982 and is currently the Allen Rothwarf Professor of Electrical and Computer Engineering. He is the author of the textbook ‘Introduction to Wireless Systems’, published by John Wiley & Sons, 2002. His research interests are in Fading Channels, Wireless communications, and Statistical signal processing for medical applications.     

MIMO系统在空时二维相关莱斯快衰落信道下的性能

与准静态独立的瑞利衰落信道模型相比较,在MIMO(Multi-Input Multi-Output)系统中,实际信道更趋向于空时相关莱斯快衰落。考虑到MIMO系统的收发分集优势以及收发两端天线阵列的空时相关性,在简单论述了MIMO系统和信道模型的基础上,该文利用多变量统计学理论,推导出MIMO系统在空时相关莱斯快衰落信道下平均成对差错概率上界的闭合表达式,并探讨了信道特性对系统性能的影响,然后给出相应仿真结果。     

莱斯信道下低精度ADC去蜂窝大规模MIMO系统的性能分析

去蜂窝大规模多输入多输出(MIMO)系统被认为是未来6G通信的关键技术之一。然而,随着接入点(APs)和用户数量的激增,硬件成本问题成为了限制系统发展的重要因素。为了有效地降低硬件成本,可以考虑在AP和用户端配置低精度的模数转换器(ADCs)。基于上述原因,本文针对莱斯衰落信道下低精度ADC去蜂窝大规模MIMO系统展开研究。通过利用加性量化噪声模型,推导了该系统使用共轭转置预编码时的可达速率闭合表达式,并且该闭合表达式有助于研究AP的数量、ADC的精度以及莱斯K-因子对于可达速率的影响。此外,在保证每个用户的服务质量和每个AP的功率约束前提下,提出了一种能够最大化总速率的功率控制算法。最后,仿真结果表明了,相较不使用功率控制算法的情况,所提的算法能够带来更大的性能增益。     

Performance Analysis of Dual-Branch Selection Combining Over Correlated Rician Fading Channels for Desired Signal and Cochannel Interference

System performances of dual selection combining over fading channels are analyzed. Fading between the diversity branches and between interferences is correlated and Rician distributed. Infinite series expressions for the probability density function, and the cumulative distribution function of the output signal-to-interference ratio are derived, which is the main contribution of this paper. Outage probability and the average bit error probability for noncoherent modulation schemes are also presented. Numerical results, presented in this paper, point out the effects of fading severity and correlation on the system performances.     

An Optimum Blind Receiver for Correlated Rician Fading MIMO Channels

A blind receiver scheme for narrowband separately- correlated Rician block fading coded MIMO systems is described. It is shown that this receiver (which can be interpreted as a limiting case of the optimum pilot-aided receiver) attains the maximum achievable throughput at sufficiently high E_b/N₀ ratio. The influence of the E_b/N₀ ratio and of the channel Rice factor on the receiver performance are studied and it is shown that, as either of these parameters increases, the advantage of the blind versus the pilot-aided receiver becomes more sensible. The results obtained support the intuition that, if the line-of-sight component is sufficiently strong, a blind scheme using only the knowledge of the fading statistics parameters matches or outperforms pilot- aided detection.     

Rician衰落信道下空时分组码的性能分析

基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的码性能原理,推导出高阶(M ary)调制下Rician衰落信道中空时分组码的符号差错率的最小距离球界,并进行计算机仿真分析了两信道下引入空时分组码的多天线系统中发射和接收天线的分集增益,发射天线数量的“地板效应”以及Rician因子K对符号差错性能的影响。     

Optimum Receiver Design for Correlated Rician Fading MIMO Channels with Pilot-Aided Detection

Two structures based on pilot symbol-aided channel receiver estimation are considered for the separately-correlated Rician fading MIMO channel. Mismatched receiver, which A decodes the received signal by first using maximum-likelihood (ML) or mean- minimum error square (MMSE) estimation of the MIMO channel matrix, and then by assuming that the estimate is exact. An optimum receiver, which does not estimate explicitly the matrix but jointly channel processes the received pilot and samples assuming known channel distribution.     

Asymptotic Mutual Information Statistics of Separately Correlated Rician Fading MIMO Channels

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.