Nakagami衰落信道的仿真方法研究

Nakagami衰落能够描述实际中所遇到的大多数衰落环境。文章提出了一个新的Nakagami衰落信道的仿真方法,用它仿真了Nakagami衰落信道的一阶、二阶统计特性并通过与其理论值进行比较验证了该方法的可靠性。该仿真方法直接基于瑞利衰落信道仿真基础之上,是对Nakagami衰落信道的一种新的研究探讨。     

Decision fusion for Wireless Sensor Networks under Nakagami fading channels

Decision fusion rules for Wireless Sensor Networks (WSNs) under Nakagami fading channels are investigated in this paper. Considering the application limitation of Likelihood Ratio Test fusion rule based on information of Channel Statistics using Series expansion (LRT-CSS), and the detection performance limitation of the Censoring based Mixed Fusion rule (CMF), a new LRT fusion rule based on information of channel statistics has been presented using Laplace approximation (LRT-CSL). Theoretical analysis and simulations show that the proposed fusion rule provides better detection performance than the Censoring based Mixed Fusion (CMF) and LRT-CSS fusion rules. Furthermore, compared with LRT-CSS fusion rule, the proposed fusion rule expands the application range of likelihood ratio test fusion rule.     

Performance analysis of cooperative network over Nakagami and Rician fading channels

This paper presents an analysis on the performance of single‐relay and multiple fixed‐relay cooperative network. The relay nodes operate in amplify‐and‐forward (AF) mode and transmit the signal through orthogonal channels. We consider maximal‐ratio combining at the destination to get the spatial diversity by adding the received signals coherently. The closed‐form moment‐generating function (MGF) for the total equivalent signal‐to‐noise ratio (SNR) is derived. The exact expressions of symbol‐error rate, outage capacity, and outage probability are obtained using the closed‐form MGF for single‐relay and multiple‐relay cooperative network with M‐ary phase shift keying (M‐PSK) and M‐ary quadrature amplitude modulation (M‐QAM) over independent and non‐identical Nakagami‐m channels and Rician fading channels. The approximated closed‐form expression of ergodic capacity is derived for both Nakagami‐m and Rician fading channels. The performance of the system is analyzed at various relay locations. The theoretical results are then compared with the simulation results obtained for binary PSK, quadrature PSK, and 16‐QAM modulation schemes to verify the analysis. Here, the expressions derived can be easily and more efficiently used to compute the performance parameters than doing Monte Carlo simulations. It is shown that cooperation is significant only for low K values for Rician by plotting cooperation gain versus K. The results show that the cooperative network performs best when the relay is located in the middle of source to destination link, at lower SNR values, and the performance of the system is worst if the relay is located closer to the source than to the destination. Copyright © 2013 John Wiley & Sons, Ltd.     

MQAM和MPSK在Nakagami衰落信道中的BER性能

基于AWGN信道中MQAM和MPSK的BER性能的近似准确分析结果，本文导出并分析了MQAM和MPSK在Nakagami-m衰落信道中采用或不采用MRC分集时的BER性能。分析结果表明，在AWGN信道、瑞利衰落信道甚至莱斯衰落信道下，现有采用或不采用MRC分集的系统性能分析结果均可以作为本文分析结果的特例。     

选择式合并方法在Nakagami信道上的性能分析

本文根据最大输出电平准则，对选择式合并在Nakagami信道上的性能作了比以往理论分析更符合实际的评价，导出了误码率的闭式解，并与最大信噪比准则时作了比较。结果表明，采用最大输出电平准则时系统的性能稍有恶化，但实现的复杂度却大为降低。     

Performance Evaluation for Forward-Link Cellular DS-CDMA over Frequency-Selective Nakagami Multipath Fading Channels

The bit-error rate (BER) for a forward-link cellulardirect-sequence code-division multiple-access (DS-CDMA) systemis evaluated. This analysis takes into account the effects ofmulti-cell interference resulting from Nakagami multipath fading,frequency selectivity, path loss and mobile user spatialdistribution. Exponentially decaying multipath intensityprofile (MIP) is adopted in the model to investigate itssignificance on the overall performance. In order to evaluatethe BER performance efficiently, saddlepoint integration (SPI)is applied in the analysis. By fixing the number of resolvablemultipaths and varying the number of fingers for the RAKEreceiver, it can be shown that the capacity of a DS-CDMAcellular system increases almost linearly with the number ofRAKE fingers.     

MC-CDMA with exponential power profile in Nakagami fading channel

A refined study of multi-carrier code division multiple access transmission over a Nakagami fading channel is proposed. The channel power is modeled with an exponential power profile rather than the uniform profile prevalent in other papers. An expression for the bit error rate (BER) is then derived. Numerical results show that MC-CDMA performances depend on the power dispersion of interferers around the desired user power.     

Nakagami衰落信道上组合SC/MRC的性能分析

研究Nakagami衰落信道上组合发射机选择合并(SC)/接收机最大比合并(MRC)天线分集系统的性能.使用矩生成函数方法,推导采用组合SC/MRC天线分集和相干检测的MPSK(M进制相移键控)、MQAM(M进制正交幅度调制)、MPAM(M进制脉冲幅度调制)、BFSK(二进制频移键控)、最小相关BFSK(BFSKmin)、差分编码BPSK(DE-BPSK)和预编码MSK(最小频移键控)等几种M进制数字调制方式在Nakagami衰落信道上的误符号率性能,获得了M进制数字调制系统误符号率性能的精确数学表达式.数值计算结果阐明了发射天线和接收天线数目以及衰落参数对数字调制系统误符号率性能的影响.     

随机序列直扩Rake系统在Nakagami信道下的性能

本文分析了用不同波形的二进制随机序列作扩频码的直扩系统在Nakagami下的性能，通过高斯近似，得到了系统的误比频率，最后给出了数值结果。     

Statistical properties of the delay spread in a two path mobile radio with Nakagami fading channel

In this paper we study the statistical properties of the rms delay spread in a two path mobile radio environment, where each path is subject to Nakagami fading. We assume a typical urban power delay profile (exponential decay) for each path. Closed form equations for the mean of the rms delay spread are derived for different values of the m parameter of the Nakagami distribution. Monte Carlo simulations are also generated and compared with the analytical results.     

A new ML detection algorithm for Orthogonal Multicode system in Nakagami fading channel

Based on the Maximum-Likelihood （ML） criterion, this paper proposes a novel noncoherent detection algorithm for Orthogonal Multicode （OM） system in Nakagami fading channel. Some theoretical analysis and simulation results are presented. It is shown that the proposed ML algorithm is at least 0.7 dB better than the conventional Matched-Filter （MF） algorithm for uncoded systems, in both non-fading and fading channels. For the consideration of practical application, it is further simplified in complexity. Compared with the original ML algorithm, the simplified ML algorithm can provide significant reduction in complexity with small degradation in performance.     

Generation of bivariate Nakagami‐m fading envelopes with arbitrary not necessary identical fading parameters

In this paper, a generation procedure of two correlated Nakagami‐m random variables for arbitrary fading parameters values (not necessary identical) is described. For the generation of two correlated Nakagami‐m samples, the proposed method uses the generalized Rice distribution, which appears in the conditional distribution of two correlated Nakagami‐m variables. This procedure can be applied to simulate diversity systems such as selection combiners, equal‐gain combiners, and maximal‐ratio combiners as well as multiple‐input multiple‐output (MIMO) receiver systems, in Nakagami‐m channels. Copyright © 2006 John Wiley & Sons, Ltd.     

Nakagami衰落信道下噪声跟踪干扰检测性能分析

针对慢跳频通信中噪声跟踪干扰的检测问题,提出了一种新的噪声跟踪干扰检测算法.该检测算法应用认知无线电中协作频谱感知方法,分析了接收信号的条件概率密度函数,研究了加性高斯白噪声信道下单跳信号存在干扰的检测性能.在此基础上,推导了Nakagami衰落信道下单跳信号存在干扰的检测概率和虚警概率,通过对检测概率和虚警概率中的多重积分进行化简,得到了检测概率和虚警概率的级数表达式.单跳信号检测后,把检测结果上报到融合中心,应用协作频谱感知中的“k out of n”准则分析了噪声跟踪干扰的检测性能.仿真结果验证了理论分析的正确性.     

A class of generalized models for shadowed fading channels

The commonly used models for shadowed fading channels arise by compounding the Nakagami distribution with others such as the log-normal and gamma distributions. A distribution that is more flexible than the Nakagami distribution is the well known Weibull distribution. In this paper, we derive a collection of generalized models for shadowed fading channels by compounding the Weibull distribution with other distributions belong to some fifteen flexible families. We also illustrate the superior performance of these models over the standard Nakagami models.     

Performance of MIMO System Through Nakagami Fading Channel with Arbitrary Fading Parameters

In this paper, the analytical and simulation results of the bit error rate (BER) performance for a multiple-input multiple-output (MIMO) system with an arbitrary number of transmit and receive antennas are developed for the uplink transmission. The fading channel is assumed to follow Nakagami-m distribution with correlation among branches. The BER is expressed in terms of Lauricella’s multivariate hypergeometric function for both independent and correlated antenna branches for BPSK system.

相关衰落信道上WCDMA系统的安全性能分析

对多输入多输出（MIMO）相关衰落信道上宽带码分多址接入（WCDMA）的安全性能进行评估,一种省时高效的解决方案是理论分析法。推导了相关 Nakagami 衰落信道上采用空时分组码和二维瑞克接收机（2D-Rake）的 WCDMA 系统的非零安全容量概率和安全中断概率的精确解析表达式。利用上述表达式,可以快速地评估收发天线数、天线相关系数、Nakagami衰落系数、平均路径衰减系数等参数对WCDMA系统安全性能造成的影响。数值计算和仿真结果相吻合,证明了以上理论分析的正确性。推导了WCDMA系统渐近安全中断概率的解析表达式。结果表明,WCDMA 系统的安全分集增益为主信道各个可分离路径上的分集增益之和,与窃听信道无关;对于恒定多径强度轮廓的同分布Nakagami衰落信道,WCDMA系统的安全分集增益为主信道的收/发天线数、多径个数以及Nakagami衰落系数四者之积。     

An approximate analytical framework for performance analysis of equal gain combining technique over independent Nakagami,Rician and Weibull fading channels

In this paper, an approximate analytical method for performance analysis of equal gain combiner (EGC) receiver over independent Nakagami and Rician fading channels is presented. We use a convergent infinite series approach which makes it possible to describe the probability of error of EGC receiver in the form of an infinite series. In this paper, we develop a new approximation method for computation of the required coefficients in this series which lets us to derive simple analytical closed-form expressions with good accuracy compared with the exact results existing in the literatures. Our proposed approximation method only needs the mean and the variance of the fading envelope, which are known for various fading distributions, and hence, bypasses the required integration over the fading envelope distribution while computing the required coefficients. This feature lets us to extend our approximation method for performance analysis of EGC receiver over independent Weibull fading channels where the required integration has not any closed-form or tabulated solutions. To give an application of our developed method, we analyze the probability of error of an EGC receiver for binary, coherent PSK (CPSK) modulation over independent Nakagami, Rician and weibull fading channels and study the effect of the fading conditions on the system performance.     

一种新的快衰落信道频域跟踪算法

该文研究了第三代移动通信系统中用户移动速度在150km/h以上时,无线信道的快衰落特性,并且在3GPP系统的协议框架下提出了一种新的基于频域的信道跟踪方法(FBP),利用快衰落信道频域上的相对稳定性,解决了由于信道参数变化的速度超过自适应算法收敛速度,而造成的在时域上无法进行信道跟踪的问题,文章给出了该算法的模拟结果,并与另一种对衰落信道的参数进行基于小波的信道跟踪算法(WBP)进行了比较,该文提出的算法具有更好的性能和更低的算法复杂度。     

A multi-criteria comparative analysis of different Rayleigh fading channel simulators

In this paper, an in-depth comparative analysis of the most accepted and approved Rayleigh fading channel simulators is presented. Our study addresses the three common methods for generating time-correlated Rayleigh fading processes: the inverse discrete Fourier transform (IDFT) method, the filtering white Gaussian noise (FWGN) method and the sum-of-sinusoids (SOS) method. Totally seven models, including the recently proposed models, are analyzed and compared with Clarke's reference model. We use four quantitative measures for judicious assessment of the quality of generated processes in terms of both first-order and second-order statistics. Additionally, these measures cover analysis in time domain as well as in frequency domain. An evaluation of the computational effort is also depicted. The simulation results suggest that the recently published Wang's model is very attractive and it outperforms all SOS-based models. We conclude that Zheng and Xiao's first model remains the best choice among Zheng and Xiao's family models. Several other important remarks and conclusions about the accuracy and the capability of the different Rayleigh fading simulators are driven from this study.     

A semi-deterministic propagation model for predicting short-term fading statistics in urban environments based on the Nakagami-m distribution

In this paper, a semi-deterministic propagation model for predicting short-term fading statistics in urban environments is presented. An approach to include surface scattering into deterministic ray-optical propagation models in urban scenarios is derived. This approach considers the coherent and incoherent components of the scattered signal. A statistical characterisation of the received signal at the received position permits to model the short-term fading for a local area around the mobile position using the Nakagami-m distribution. The parameters of the Nakagami-m distribution are obtained taking into account the real environment from a digital map information of the urban area. Computer simulation results and experimental data are compared.