Rayleigh衰落信道的建模与仿真

以经典Jakes模型的发展为线索,分析比较了具有代表性的改进Jakes类和非Jakes类模型,通过以瑞利衰落波形的二阶统计特性为判别信道效能的依据,得出高效信道模型所具有的参数特征以及仿真多个独立瑞利衰落波形的方法等.仿真数据表明,模型的精确度是以计算量和复杂度为代价.     

瑞利衰落信道Jakes模型的研究与性能分析

无线衰落信道是无线通信系统的重要组成部分,因此信道建模和仿真对于无线通信系统的开发具有极其重要的作用。文章通过对平坦瑞利(Rayleigh)衰落信道进行仿真建模研究,给出了瑞利衰落信道可以采用Jakes模型进行建模的分析结果。     

一种新的MIMO无线信道建模方法

文中提出了一种时变宽带MIMO信道的建模方法。该方法利用修正的Jakes衰落模型，用正弦波形叠加的方法，建立了一个频率选择性瑞利衰落多普勒MIMO信道模型。MATLAB仿真证实了该方法的可行性。     

多径非相关瑞利信道生成的改进

提出一种多径非相关瑞利信道生成改进方法。和目前其他瑞利信道生成方法相比，该方法不仅能满足瑞利信道所具备的统计特性，而且保证信号多径传播中各径信号不相关特性。通过仿真可以看出该方法的单径信道二阶特性和现有模型统计特性相仿，而多径非相关性明显较好。     

基于改进Jakes模型的高速铁路LTE系统信道建模

随着LTE技术的日臻完善,其在高铁环境下的信道建模分析也日益重要。文章针对时速超过300km/h情况下的高铁无线信道建模进行了分析与研究,对理想模型和Jakes模型进行改进,使其更加符合高速运动的情况。仿真结果表明所建立的模型为一个平稳随机过程,且信号包络服从瑞利均匀分布。     

MIMO—OFDM相关信道的研究

本文主要研究了MIMO信道的相关性及其相关矩阵的计算问题,并结合OFDM技术。分析了MIMO-OFDM相关信道的理论特性。运用Jakes信道模型,对独立传输信道、完全相关传输信道、部分相关传输信道进行了仿真,进一步分析了MIMO-OFDM相关多径信道的有关特性。     

基于Matlab的独立瑞利衰落模型的仿真

本文提出的一种基于正弦和的仿真瑞利衰减信道的仿真模型,并用Matlab对该模型的统计量进行了仿真。该仿真模型对所有的正弦波采用了随机初始相位和有条件的随机多谱勒频率。经理论计算与仿真表明:在正弦波数量较少的情况下该模型的统计量与理论值非常接近,而且能被直接用来产生频率选择性多径不相关衰弱波形。     

高速无线信道建模与仿真

在考虑了高速铁路地理环境和高速等因素的基础上,综合考虑了多普勒效应和多径效应的影响,针对现有小尺度衰落无线信道模型的不足,应用了一种适合高速铁路环境下的无线信道模型。在Jakes信道仿真器的基础上,建立高速铁路环境下的无线高速信道模型。应用Matlab仿真软件对信道多普勒功率谱密度和信道包络进行仿真,说明信号建模的合理性。仿真结果与理论分析吻合,从而说明了模型的有效性。     

一种新的MIMO信道模型

实际无线通信环境中发送天线之间以及接收天线之间存在相关性.针对以上特点,从多径MIMO信道的特性出发,首先建立发射天线相关系数矩阵和接收天线相关系数矩阵,并将它们引入无线信道的莱斯MIMO信道模型中.最后通过分析LOS MIMO信道相关模型和瑞利衰落MIMO信道相关模型,给出了具体的建模步骤.仿真结果表明采用本文方法产生的信道模型的MIMO系统误码率更低,从而验证了该信道模型能够较好地模拟MIMO系统的空间信道.     

基于空时相关性的MIMO无线信道建模及仿真

针对多输入多输出无线信道的空时相关性，文章提出了一种改进的MIMO无线信道模型。该模型利用改进的Jakes模型仿真器来产生独立同分布零均值的复高斯随机变量，从而保证各个传播路径间的相关性很小。仿真结果表明改进的MIMO无线信道模型能够准确的描述出空时相关的MIMO无线信道的统计特性，即空间相关性随天线单元间距增大而战小，随散射信号角度扩展增大不是一致减小．     

On the generation of correlated Rayleigh fading envelopes for accurate simulation of diversity channels

The generation of correlated Rayleigh fading envelopes based on mobile radio channel characteristics for realistic simulation of diversity systems was documented in 1974 by Jakes. In this letter, a survey of recent algorithms which draw upon Jakes' work will be given, as well as an illustration of their shortcomings. Subsequently, a procedure is presented for the generation of multiple equal-power correlated Rayleigh fading envelopes, with desired cross-correlations and autocorrelation functions specified so as to model channel conditions under the general assumption of isotropic scattering. The algorithm presented will enable accurate simulation and investigation of the effect of correlated fading on diversity schemes.     

An efficient simulation of multiple correlated Rayleigh fading envelopes

In order to better assess the performance of wireless communication systems, it is desirable to produce multiple Rayleigh fading envelopes with specified correlations. In this paper, we analyze theoretically a procedure which generates correlated Gaussian random variables from independent Gaussian random variables and give a physical explanation for the limitation of this procedure. Then, based on some uncorrelated Rayleigh fading envelopes, a simple but efficient procedure for generating an arbitrary number of cross-correlated Rayleigh fading envelopes is proposed. Simulation results and computational complexity analysis are presented, which show that the proposed method has some advantages, such as high accuracy, low computational complexity and easy implementation, over the conventional simulation method.     

Multiple Rayleigh fading channels modeling based on sum‐of‐sinusoids model

Assessing the performance of communication system is critical in system design in mobile communication study. Numerous methodologies have been employed to facilitate the assessment, amongst which generation of multiple fading channels is widely used and thus of great interest to us. Specifically, multiple Rayleigh fading channels are extensively utilized in simulation of the following: MIMO channels, amplify‐and‐forward fading channels, frequency‐selective channels, etc. The existing model to generate Rayleigh fading channels is the sum of sinusoids (SOS). However, the SOS model is flawed, as it sometimes generates impure correlated channels. That is, a small fraction of correlated channels are generated when we anticipate uncorrelated or vice versa. In this paper, on the basis of the concept of SOS, we introduce a new computational model to generate Rayleigh channels that completely match our anticipation—fully uncorrelated or fully correlated channels. Additionally, we also propose a design method to reduce the number of sinusoids, thus we achieve reduced computational cost of the system. Simulation results and comparison analysis indicate that, with reduced computational cost, our method is able to produce pure Rayleigh fading channels— 100% uncorrelated or the opposite.Copyright © 2013 John Wiley & Sons, Ltd.     

Jakes fading model revisited

The Jakes fading model is a deterministic method for simulating time-correlated Rayleigh fading waveforms and is still widely used today. However, since it is difficult to create multiple uncorrelated fading waveforms with this model, the authors propose modifications to the model which solve this problem.<>     

The simulation of independent Rayleigh faders

Multiple independent Rayleigh fading waveforms are often required for the simulation of wireless communications channels. Jakes (1974) Rayleigh fading model and its derivatives based on the sum-of-sinusoids provide simple simulators, but they have major shortcomings in their simulated correlation functions. A novel sum-of-sinusoids fading model is proposed and verified, which generates Rayleigh fading processes satisfying the theoretical independence requirements and providing desired power spectral densities with ideal second-order moment. The effects of replacing sinusoids in the proposed model by their approximate waveforms are also analyzed and tested. Performance evaluation and comparison are provided, using the quality measures of the mean-square-error of autocorrelation function and the second-order moment of the power spectral density.     

Fading model for antenna array receiver for a ring-type cluster of scatterers

This correspondence presents an alternate method for simulating the time-varying flat fading wireless channels for the antenna array receivers, in which the discrete ring of scatterers is incorporated around the mobile transmitter to model the spreading of azimuth. The ring-type cluster of scatterers continuously changes due to the movement of the mobile unit. Under this time-varying environment, each scatterer, at successive stages of the ring, is correlated with the scatterers at preceding stages of the ring using the second-order Markov modelling. The correlation of fading waveforms generated with the proposed paradigm is compared with the expected analytical correlation, which clearly depicts that the simulation results are consistent with the findings based on Jakes’ model.     

Model of independent Rayleigh faders

The Jakes (1974) fading model is widely accepted for the simulation of wireless communication channels, but it is very difficult to create a multiple uncorrelated fading waveform. Dent et al. (1993) proposed a modified version of the Jakes model, but it does not solve the problem very well. Li and Huang (2002) also proposed a new model, which overcomes the undesired properties. But its computational complexity is twice as great as that of the Jakes and Dent models. A novel model is proposed. Its correlation properties are as good as those of the Li and Huang model, yet computational complexity is reduced by a half.