平坦Rayleigh衰落信道中基于多项式预测Turbo乘积编码MDPSK的研究

本文提出一种基于多项式预测的判决反馈差分检测(PP—DFDD)来改善平坦Rayleigh衰落信道中Turbo乘积编码多元DPSK系统(TPC—MDPSK)性能的新方法。相对于传统的判决反馈差分解调而言，该新方法无需任何先验的信道信息，而且计算量较小。数值仿真结果表明该新方法可以改善衰落信道中TPC—MDPSK系统的错误平底。     

基于LS信道估计和分集接收的Turbo乘积编码OFDM系统的性能研究

该文研究OFDM系统中低复杂性最小二乘方(LS)信道估计技术,为了改善LS估计的OFDM在严重多径信道中错误平底效应,分集接收和Turbo乘积编码用于系统设计。数值仿真结果表明,Turbo乘积编码和分集接收可以减小LS估计的OFDM系统的错误平底效应,其性能比已知信道参数系统的性能只恶化4dB。     

两路接收分集Turbo乘积编码PSAM系统的研究

提出具有两路接收分集Turbo乘积编码引导符号辅助调制(TPC-PSAM）的16QAM系统的实现方法。该系统将Turbo乘积编码和分集接收用于改善16QAM系统在平坦衰落信道中的性能。通过对衰落信道中的数值仿真，结果表明具有接收分集的TPC-PSAM系统比TPC-PSAM系统明显的改善，同时可以减小接收机在不同衰落信道中的性能差异。     

基于Turbo乘积码的自适应编码调制技术研究

随着高速无线数据通信的发展,自适应调制技术逐渐成为业界研究的热点之一。研究了MQAM自适应调制技术,分析了自适应调整区间的划分方案,设计了基于Turbo乘积码的自适应编码调制方法,提高了系统的频谱利用率。     

Turbo乘积码在衰落信道中的应用

基于Turbo乘积码的编译码原理,利用Matlab仿真工具,对以(64,57,4)扩展汉明码为子码的Turbo乘积码进行迭代次数、量化比特数等不同参数的性能仿真,根据仿真结果选取最佳的设计参数,同时通过仿真给出了Turbo乘积码在衰落信道中的应用效果。结合Matlab仿真,在Quartus环境中完成编译码算法的硬件设计与调试,并将其应用到无线通信调制解调器中。测试结果表明,Turbo乘积码显著改善了调制解调器在衰落信道中的误码性能。     

利用限幅器改善Rayleigh衰落信道中Turbo乘积编码PSAM系统的性能

该文研究了 Rayleigh衰落信道中 Turbo乘积编码辅助符号调制(TPC-PSAM)系统的性能并提出一种利用软信息限幅来改善的 TPC-PSAM性能的新方法,通过对不同的 Rayleigh衰落信道中 TPC-PSAM系统的性能仿真,结果表明在 10-4误比特率下,这种新方法对 TPC-PSAM的性能有5～8dB的改善。     

Turbo乘积码快速编码的FPGA实现

Turbo乘积码是一种性能卓越的前向纠错码,具有译码复杂度低,且在低信噪比时可以获得近似最优的性能。TPC编码的主要指标是时延,论文给出了一种基于FPGA的TPC编码方法,采用行列同时编码,编码时延小,复杂度低。     

衰落信道中Turbo码的应用研究

Ｔｕｒｂｏ码以其优异的性能而迅速成为近年来信道编码领域研究的热点。本文针对无线信道的特点,提出了在无线衰落信道中Ｔｕｒｂｏ码的构造方法,并基于非选择性瑞利慢衰落信道模型,分析了Ｔｕｒｂｏ码在不同信道条件下的性能。     

无线衰落信道下的分集接收技术

在分析无线信道衰落特性的基础上,介绍了抵抗衰落的分集接收技术.空时编码技术有效地结合了发送分集、编码和调制技术,提高了衰落信道的传输性能.     

Turbo码在最大比合并分集接收系统中的性能分析

该文提出了turbo码在最大比合并分集接收无线通信系统中纠错性能的联合上界。基于误差积分函数的简化计算式,推导了分集接收的多路信道分别具有不同衰落特性时,成对差错概率的精确表达式。以瑞利衰落信道为例,对采用turbo码的分集接收无线系统的性能进行了数值计算和仿真。结果表明：turbo码纠错性能联合上界数值计算式与仿真结果一致,可普遍用于信道衰落统计特性各不相同的分集接收系统。     

采用两条支路分集接收的相关瑞利衰落信道容量

本文研究采用两条支路最大比合并(MRC)或选择合并(SC)分集接收的相关瑞利衰落信道理论容量推导恒定发射功率自适应M进制正交幅度调制(M-QAM)的频谱效率,并将它们与独立同分布瑞利信道理论容量进行比较,其结果对收发信机之间无视距分量路径、接收机上分集天线之间的距离小于半个波长的无线通信系统设计具有指导作用.     

Combining Pilot-Symbol-Aided Techniques for Fading Estimation and Diversity Reception in Multipath Fading Channels

A novel pilot-symbol-aided (PSA) fading estimation technique that combines the estimates from a conventional PSA technique and a bandwidth-efficient PSA technique to achieve better performances is proposed for digital signals in multipath fading channels. The conventional technique has better performances at low signal-to-noise ratios (SNRs), while the bandwidth-efficient technique is superior at high SNRs. Monte Carlo computer simulation has been used to assess the effects of the proposed combining technique on the bit-error-rate (BER) performances of 16-ary quadrature-amplitude-modulation (16QAM), with and without two-branch diversity reception, in a flat Rayleigh fading channel. Results have shown that the combining technique has the advantages of both of the conventional technique and the bandwidth-efficient technique and is more preferred for use with diversity reception. Man-Hung Ng received a BSc degree in Computer Studies from City University of Hong Kong in 1991. He worked as a computer programmer in Hong Kong from 1991 to 1995. In 1996, he obtained a MSc degree in Communication and Radio Engineering from King's College London. He joined the University of Hong Kong as a research assistant in 1997, and completed a PhD degree in mobile communications in 2001. He joined Lucent Technologies N.S. UK in 2001 and is now a principal standards engineer. Sing-Wai Cheung received the BSc degree in Electrical and Electronic Engineering from Middlesex University, U.K. in 1982 and the PhD degree from Loughborough University of Technology, U.K. in 1986. From 1986–1988, he was a post-doctorate research assistant in the Communications Research Group of King's College, London University. During 1988–1990, he was with the Radio and Satellite Communications Division in British Telecom Research Laboratories (now British Telecom Laboratories). He joined the Department of Electrical and Electronic Engineering at the University of Hong Kong in 1990 and is now an Associate Professor. He contributes regularly courses on mobile and satellite communications systems. His current research interests include modulation, coding, fading compensation and diversity and MIMO for mobile and satellite communications systems.     

Rayleigh衰落信道中的CDMA多用户分集接收性能

本文针对频率选择性Ｒａｙｌｅｉｇｈ衰落信道，设计了一种ＣＤＭＡ多用户检测器分集结构，通过该结构，高斯信道多用户检测算法可以有效地应用到Ｒａｙｌｅｉｇｈ衰落信道中，仿真结果表明，分集合并实现的多用户中以显著改善衰落信道的误码性能，其处理多址干扰能力并不因分集而受到影响，另外，本文还对不同的合并以及不同的检测地作了性能上的比较。     

衰落信道下Turbo网格编码调制在图像传输中的性能研究

基于Turbo码和网格编码调制的特点,该文分析了TTCM的具体编译码方法,并分析比较了TTCM在8PSK调制下结合两种典型映射方案UP(Ungerboeck Partitioning),BP(BlockPartitioning)在Rayleigh信道中用于静态图像传输时的性能,给出了计算机仿真结果和评价图像传输质量的峰值信噪比(PSNR).     

A Moment-Generating Function (MGF) Derivative-Based Unified Analysis of Incoherent Diversity Reception of M-ary Orthogonal Signals over Independent and Correlated Fading Channels

Exact, closed-form, error probability expressions for noncoherent M-ary frequency-shift-keying (MFSK) systems that employ postdetection equal-gain diversity over Rayleigh, Rician, and Nakagami-m channels are derived using a Laplace derivative formula. Both independent and generically correlated fading cases are considered. For independent fading, closed-form solutions are also derived for both Nakagami-q fading (either with identical or dissimilar fading statistics) and mixed fading cases. Previous results are shown to be specific instances of our general expressions. In addition, a concise, derivative formula is derived for calculating the bit error rate of square-law detected multichannel binary differential phase-shift-keying (DPSK) signals. All of these expressions are applicable in many cases of practical interest and provide accurate predictions of the performance of both binary and M-ary orthogonal signaling over generalized fading channels with arbitrary parameters.     

未知相位信道下 Turbo码编码DPSK信号的联合迭代解调解码

本文提出了未知相位信道下Turbo码编码DPSK信号的联合迭代解调解码算法 .推导了未知相位信道的最大后验概率 (MAP)算法 ,推导表明该MAP算法同样可用前向、后向递推方程来有效实现 .其次 ,采用等效信道的方法将未知相位信道的Turbo码解码问题化为AWGN信道下Turbo码的解码问题 .最后 ,引进了联合迭代解调解码算法 ,可用于Turbo码的解调解码 .模拟表明本文算法可有效用于未知相位信道Turbo码的解码