OFDM-MQAM在相关Nakagami-m衰落信道上的性能分析

本文研究频率选择性相关Nakagami衰落信道上采用最大比合并(MRC)分集接收的正交频分多路复用M进制正交幅度调制(OFDM-MQAM)系统.使用矩生成函数(MGF)方法和高斯超几何函数、Appell超几何函数或Lauricella函数,推导任意衰落参数频率选择性相关Nakagami衰落信道上MRC分集接收的OFDM-MQAM系统的误符号率(SER)性能,获得了OFDM-MQAM误符号率的一个新的解析表达式.数值计算结果阐明了多径路径数、Nakagami衰落参数和信道脉冲响应抽头间的相关系数对OFDM-MQAM误符号率性能的影响.     

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.     

基于MATLAB的Nakagami衰落信道仿真与分析

由于Nakagami衰落能够准确地表示实际中所遇到的大多数衰落环境，因而本文基于MATLAB针对Nakagami衰落信道仿真了它的统计特性，包括接收信号的复包络模拟和在具有最大比合并分集下的电平通过率及平均衰落持续时间的性能分析。重点在于理解和建立采用MATLAB进行信道信真的方法及对Nakagami衰落信道本身统计特性的理解。     

相关MIMO Nakagami衰落信道上MQAM WCDMA系统的性能分析

使用矩生成函数(MGF)方法,推导相关MIMO Nakagami衰落信道上WCDMA系统下行链路中采用组合二维瑞克(2D RAKE)接收机和发送分集的M进制正交幅度调制(MQAM)的平均误符号率精确解析表达式.利用获得的解析表达式,研究天线阵结构(如发射天线和接收天线的数目、天线间的距离)和工作环境(如衰落系数、角度扩展、多径延迟轮廓等)对MQAM WCDMA系统性能的影响.     

衰落信道下MFSK/FFH系统抗最坏部分频带干扰性能研究

引入Nakagami-m衰落模型,对MFSK/FFH系统在衰落信道下抗最坏部分频带干扰性能进行了研究,给出了部分频带干扰最佳干扰系数表达式和Nakagami衰落信道下MFSK/FFH误码率公式并进行了仿真验证,分析了不同衰落参数和分集数对系统性能的影响,最后仿真对比了采用自动增益控制合并(Adaptive Gain Control)与乘积合并(Product Combining)时MFSK/FFH系统的性能表现.结果表明:Nakagami衰落信道下,MFSK/FFH系统的分集接收特性能有效对抗最坏部分频带干扰,采用AGC合并算法比PC合并算法能更好的改善系统性能.     

协同通信中分集合并性能分析

无线通信信道时变多径的传输特性严重影响了传输系统的性能,必须采取有效的措施来对抗信道衰落。分集接收技术成本低廉,性能优越,在无线通信技术中广泛使用,是对抗无线信道衰落最有效的技术之一。文中详细地叙述了分集接收合并的原理,给出了严密的数学公式,通过理论推导,研究了三种合并技术(最大合并比MRC、选择合并SC、等增益合并EGC)的误码率和合并增益,仿真并分析了其在瑞利衰落信道下的性能,为实际应用提供参考。     

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。     

无线相干光通信空间分集接收合并技术

空间分集接收能补偿大气湍流造成的信道衰落。在给出相干检测分集接收的系统模型和晴朗大气信道模型的基础上,考虑子孔径间信号相关性,分析了等增益合并分集和最大比合并分集的误码率性能,并就中断概率与选择分集进行了比较。分析结果表明,空间分集接收能够明显改善相干光通信系统的性能,并且接收信号间的空间相关性越小分集接收的性能越好,其中最大比合并分集性能相对其他两种合并方式优势明显,选择分集性能最差,但它与等增益合并分集的差距不大,同时选择分集实现相对容易,在工程应用中要综合考虑实现的难易程度和性能。     

级联正交/PN码DS-CDMA系统在Nakagami信道下的性能

本文分析了级联正交/长PN码的互相关和自相关特性 .分析的结果用来计算在这种新的扩频方案下直接扩频系统在多用户和多径衰落下的系统性能.多径衰落信道为Nakagami 信道.接收端采用最大比率分集接收机.     

一种改进的衰落分集信道量化FSMC模型及其性能分析

针对无线快衰落信道,本文提出一种改进的一阶FSMC量化模型,并提出一种通过分析基带差错序列游程分布特性的新方法,来验证Markov模型的性能.文中给出FSMC量化模型参数提取方法,并分别通过对采用选择性合并、等增益合并、最大比合并以及不采取分集合并的Nakagami分布衰落信道的仿真,证实了改进的量化FSMC模型的准确性.     

Performance of Up-link MC-CDMA System with Frequency Offset and Imperfect Channel Estimation Simultaneously over Nakagami Fading Channels

In this paper, effects of carrier frequency offset on performance of uplink MC-CDMA (Multi-Carrier Code Division Multiple Access) system in Nakagami fading channel are investigated through the theoretical analysis and Monte Carlo computer simulations. Both perfect maximal-ratio combining (MRC) and equal gain combining (EGC) receivers are analyzed; the impact of imperfect channel fading estimation on the performance of MRC is also explored. The performance of MC-CDMA system is also compared with that of the conventional single-carrier DS-CDMA system. Our results indicate that the performance of MC-CDMA system is sensitive to even small values of carrier frequency offset and that the performance of MC-CDMA system improves as number of subcarriers increases. In perfect channel fading estimation, the overall performance of MRC is superior to EGC. However, when imperfect or inaccurate channel fading estimation exists, which leads to serious performance degradation, EGC becomes superior to MRC. This revised version was published online in July 2006 with corrections to the Cover Date.     

IS-95反向信道在Nakagami(m)多径衰落信道下的性能分析

IS-95是北美制定的基于CDMA技术的无线空中接口标准,本文给出了IS-95反向信道调制和解调过程的数学模型。一般认为Nakagami(m)分布较好地描述了多径衰落信道,本文分析了IS-95反向信道在Nakagami(m)衰落信道下的误码率,结果可以用来综合分析系统和信道的不同参数对系统性能的影响。     

Efficient computation of MRC diversity performance in Nakagamifading channel with arbitrary parameters

A very efficient numerical expression is described for MRC diversity performance in a Nakagami fading channel with arbitrary parameters, including all possible conditions of received signal strength and arbitrary fading figures     

Expression for evaluating performance of BPSK with MRC in Nakagami fading

A strikingly simple and fast to compute expression is derived for the performance of binary phase shift keying (BPSK) with maximal ratio combining (MRC) diversity in a Nakagami (1960) fading channel. The expression is valid for all Nakagami-m parameters. Furthermore, no concession is made as far as the accuracy of the results is concerned.     

Average error rate for coherent MPSK signals in Nakagami fadingchannels

The error rate performance of coherent M-ary phase shift keyed signals in slow nonselective Nakagami fading and additive white Gaussian noise channel is analysed. For real values of the Nakagami fading parameter m, a simple formula is presented for the symbol error rate that can be easily evaluated via numerical integration. A closed-form expression is derived for integer values of m. The effect of N-order MRC diversity reception is also considered     

基于机会中继和最大比合并下的协作通信系统

分析了机会中继和最大比合并下的协作通信系统性能.首次给出了Nakagami衰落信道下的符号错误率和中断概率的精确闭式结果.通过对中断概率的近似结果分析发现对于任意一条源节点-中继-目的节点链路,分集增益均由源节点-中继链路和中继-目的节点链路中的深衰落链路决定.     

Performance analysis of maximal ratio combining in the presence ofmultiple equal-power cochannel interferers in a Nakagami fading channel

The effect of cochannel interference on the performance of digital mobile radio systems in a Nakagami (1960) fading channel is studied. The performance of maximal ratio combining (MRC) diversity is analyzed in the presence of multiple equal-power cochannel interferers and additive white Gaussian noise. Closed-form expressions are derived for the average probability of error as well as outage probability of both coherent and noncoherent (differentially coherent) binary frequency-shift keying and binary phase-shift keying schemes in an environment with cochannel interference and noise. The results are expressed in terms of the confluent hypergeometric function of the second kind, a function that can be easily evaluated numerically. The analysis assumes an arbitrary number of independent and identically distributed Nakagami interferers     

BER performance of DQPSK in Nakagami fading with selection diversity and maximal-ratio combining

A new expression for the average bit-error rate (BER) of differential quadrature phase-shift keying in slow frequency-nonselective Nakagami fading is derived for a space-diversity receiver having a cascade arrangement of L groups of M-branch selection combiners and an L-branch maximal-ratio combiner (MRC). This allows the use of a large number of antennas, for performance improvement, and a small number of M inputs to the combiners, for low complexity. The average BER performance of the cascade receiver is investigated for different fading severity conditions characterized by the Nakagami m factor, and compared with the conventional MRC receiver. As the fading gets less severe (m increases), performance improvement over the conventional MRC scheme is only noticeable for the larger range of average signal-to-noise ratio.     

STBC块传输系统中的一种新型分集合并算法

该文在二发一收的空时分组码(STBC)单载波块传输系统中,提出一种空时和多径分集合并接收算法。通过基于STBC的单载波频域均衡(STBC-SC-FDE)算法得到对发送信号的估计,以此和信道状态信息(CSI)分离接收信号中的各多径分量,对各多径分量分别采用STBC合并,最后再将各多径分量的合并输出结果按照最大比(MRC)的方式进行合并,从而实现空时二维RAKE接收。该算法在较低的计算复杂度情况下,可以同时获得发射分集和多径分集,Monte Carlo仿真验证了该算法的性能。     

Exact evaluation of maximal-ratio and equal-gain diversityreceivers for M-ary QAM on Nakagami fading channels

Exact integral expressions are derived for calculating the symbol-error rate (SER) of multilevel quadrature amplitude modulation (MQAM) in conjunction with L-fold antenna diversity on arbitrary Nakagami fading channel. Both maximal-ratio combining (MRC) (in independent and correlated fading) and equal-gain combining (EGC) predetection (in independent fading) diversity techniques have been considered. Exact closed-form SER expressions for two restricted Nakagami fading cases (MRC reception) are also derived. An exact analysis of EGC for MQAM has not been reported previously, despite its practical interest. Remarkably, the exact SER integrals can also be replaced by a finite-series approximation formula. A useful procedure for computing the confluent hypergeometric series is also presented