Turbo网格编码调制在无线信道下的性能分析

基于Turbo码和网格编码调制的特点,介绍了TTCM(Turbo Trellis Coded Modulation)的基本结构及编译原理,结合3G中IMT2000标准的具体要求,提出一种TTCM方案,并在室内和车载信道环境下进行性能仿真,然后与标准中提出的1/3码率Turbo码性能比较,得出TTCM系统不仅能获得较好的传输质量,同时更能有效地提高频带利用率,是一种最佳的选择方案。     

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。     

衰落信道中不同集分割的多级编码调制方案的性能研究

本文以MLC系统各等价信道的信道容量为依据^[1],选用不同码长的BCH码系列作为MLC系统中各级的分量码,通过计算机模拟,比较了三种不同的集分割方法所构成的MLC/MSD方案,分别在AWGN和Rayleigh衰落信道中、8ASK调制方式下的性能.模拟结果表明:UP分割在AWGN信道中具有最好的性能;BP分割可自适应于AWGN和Rayleigh衰落混合的移动衰落信道,是MLC方案应用于移动衰落信道中的最佳集分割方案.     

RS-MPSK编码调制在传输压缩图像的Rayleigh衰落信道中的性能

本文研究了两种结构的ＲＳ－ＭＰＳＫ编码调制方案在传输压缩图像的Ｒａｙｌｅｉｇｈ衰落信道中的性能。采用计算机仿真的方法得到了该方案在Ｒａｙｌｅｉｇｈ衰落信道中的误比特率,并与理论上限进行了比较,将方案用于传输压缩图像时,可大大提高系统的性能,具有较高的理论意义和衫价值。     

衰落信道下Turbo码在宽带CDMA系统中的应用研究

本文在研究Turbo码在衰落信道下典型性能分析的基础上,提出了在宽带CDMA系统中结合RAKE接收机实现路径分集后Turbo码的性能分析方法.在高斯和衰落信道下,采用计算机仿真进行了实际系统的模拟,结果表明宽带CDMA系统中Turbo码对抗衰落的性能有了很大提高.     

衰落信道中自适应编码调制技术的研究

介绍了在慢衰落信道中自适应编码调制技术的基本原理,比较了几种自适应编码调制系统的技术特点,设计了一种基于Turbo乘积码的自适应编码调制多媒体通信方案。     

网格编码调制在快衰落移动信道中的应用

文章在前期所做的关于快衰落移动信道纠错抗干扰工作的基础上,介绍了ＴＣＤＭ技术的原理及其关键技术,分析了网络编调制研究的几个突破点。     

Turbo码联合信道估计在瑞利衰落信道中的运用

如果将信道衰落信息提供给Turbo译码器,则在瑞利衰落信道下更能发挥Turbo码的优良特性。该文分析了在瑞利衰落信道下Turbo译码算法,用Jake方法模拟瑞利衰落信道,采用将多时隙加权平均(WMSA)信道估计和Turbo码结合起来的算法。仿真结果显示此系统性能优异。     

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。     

时变衰落信道中自适应调制编码技术

在移动通信系统中,由于无线时变衰落信道的特点,使通信过程存在大量的不确定性,自适应方式在信道条件好时提高了传输速率或减小发送功率,在信道条件差时降低了速率或增大功率。通过仿真结果证明,根据信道的优劣情况进行自适应调制的系统在保持较低的误码率性能的同时,能提高了系统的传输速率,从而增强传输的可靠性并可提高频带利用率。     

Turbo Trellis Coded Modulation with Enhanced Transition Metric over Rayleigh Fading Channels

This paper investigates the performance of a new Turbo Trellis Coded Modulation scheme over correlated flat fading channels with channel interleaving. The novelty of the scheme is based on the application of a new modified transition metric incorporated in the symbol-by-symbol MAP algorithm. We consider frequency non-selective, slow Rayleigh fading channels. Extensive simulation results together with EXIT chart analysis show that the proposed scheme achieves better performance compared to the conventional transition metric when channel state information is not available at the decoder. Kostas V. Koutsouvelis was born in Thessaloniki, Greece, on July 16,1970. He received the degree Diploma in Electrical Engineering from Aristotle University of Thessaloniki, Greece in 1996 and the Master degree in Satellite Communications Engineering from University of Surrey in 1997. From 1998 to 2003 he was involved in the development of V5.2 interface as a senior software designer in Intracom plc. In 2004 joined the research and development division of Hellenic Telecommunication Organization (OTE) and his also PhD candidate at Aristotle University of Thessaloniki working with Turbo codes and Turbo Coded Modulation. Christos E. Dimakiswasborn in Serres, Greece, on July 27, 1955.He received the degree Diploma in Electrical Engineering from the Aristotle University of Thessaloniki, Greece, in 1980. Working in the satellite communications and in the error correcting coding area he received his PhD degree in digital telecommunications from the Aristotle University of Thessaloniki, Greece, in 1994. In 1980 he joined the Department of Electrical Engineering, Telecommunications Division of the Aristotle University of Thessaloniki as a research fellow. Since 1997 he is a lecturer of digital communications at the same University. Presently, his research interests include digital modulations, coding theory, satellite and mobile communications and system simulation. Stamatis S. Kouris was born in Corfu, Greece. He received the degree of Doctor Engineer in Electrical Engineering from the University of Rome, Italy and the Diploma of Specialization in Telecommunications of the Instituto Superiore, University of Rome, in 1960 and 1963 respectively. In 1971 he was awarded the PhD Degree of the University of Edinburgh, UK. In the 1974 he was awarded a specialization Diploma in administration from the University of Pomona CA, USA. He is a member of the Technical Chamber of Greece, URSI, IRI and other organizations. Since 1964 he has been involved in research on radio-propagation, antennas and microwaves, working mainly at the Fondazione Bordoni, Italy, University of Edinburgh, UK and University of Thessaloniki, Greece. He has published several papers on radio-propagation, antennas, communication transmission and microwaves and millimeter-waves devices. In 1976 he joined with the Department of Electrical Engineering, School of Engineering Science, Aristotle University of Thessaloniki. He served as professor of telecommunications from 1978 to 2002. Since 2002 he is an emeritus professor.     

Rayleigh衰落信道中多级编码调制的不等错误保护

本文研究了Rayleigh衰落信道中以信道容量规则为设计准则的多级编码调制系统的不等错误保护性能的实现及其改进.在详细分析了多级编码调制的不等错误保护原理的基础上,设计了一种针对8ASK调制的非均匀信号星座.理论分析与计算机仿真均表明,非均匀信号星座的设计能够增强多级编码调制系统的不等错误保护能力,在不展宽频带的前提下有效地提高Rayleigh衰落环境下数字通信系统的传输质量.     

Turbo Decoding of Super-Orthogonal Space-Time Trellis Codes in Rayleigh Fading Channels

Space-time trellis codes have shown to provide a good performance in Rayleigh fading channels. Recently Super-orthogonal space-time trellis codes have shown to outperform these codes, and also provide a systematic design method to maximize diversity and coding gain in quasi-static Rayleigh fading channels. We investigate the performance of these new codes in rapid Rayleigh fading channels and further propose two concatenated versions of these codes. We further investigate the effect of imperfect channel state information on one of the concatenated versions. Some simulation results of the various concatenated schemes in quasi-static and rapid Rayleigh fading channels are presented. Jayesh N. Pillai received the B.Tech degree in Electrical and Electronic Engineering from the University of Calicut, Kerala, India in 2001. He is currently pursuing an MScEng degree in Electronic Engineering at the School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal, Durban, South Africa. His research interests are in the area of wireless communications, including multiple-antenna systems, space-time coding and channel coding. Stanley Henry Mneney obtained his B.Sc.(Hons) Eng. Degree from the University of Science and Technology, Kumasi in Ghana in 1976. In 1979 he completed his M.A.Sc. from the University of Toronto in Canada. In a Nuffic funded project by the Netherlands government he embarked on a sandwich Ph.D. programme between the Eindhoven Univesity of Technology and the University of Dar es Salaam, the latter awarding the degree in 1988. His co-supervisors were Prof Jens Arnbak and Prof Ramje Prasad representing the two Universities. The research area was on the application satellite technology to provide low cost systems and services to the rural population in the developing countries.Prof Mneney has taught at the Universities of Dar es Salaam, Nairobi, Durban Westville and he is currently an Associate Professor and Deputy Head of School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal in South Africa. His research interest includes Signal and Image processing, radio propagation and communication systems.     

一种基于TCM的信道编码与物理层网络编码的联合设计

该文在双向中继信道中基于网格编码调制(Trellis Coded Modulation, TCM)提出了一种信道编码与物理层网络编码的联合实施机制。该机制采用TCM,将编码和调制统一考虑,提高了编码序列的自由距离,从而获得更高的编码增益。此外,利用卷积码和MAC-XOR网络编码的线性性质,使得中继节点只要直接估计网络编码的码字,这样中继节点进行TCM译码的复杂度减少了50%。该机制同时考虑信道编码技术、调制技术以及物理层网络编码三者联合设计的问题,既提高信息传输率,又保证了可靠性。     

快衰落瑞利信道下分布式线性卷积空时码的分集增益

在无线中继网络中,中继节点间的随机传输延迟将导致显著的性能下降。因此,针对慢衰落瑞利信道提出可容忍随机时延的分布式线性卷积空时码(DLC-STC),但该类空时码在快衰落信道下的分集性能尚未明确。该文从理论上证明了DLC-STC在快衰落瑞利信道下的分集增益。分析表明,DLC-STC虽然最初是在慢衰落信道下被提出的,但它在快衰落瑞利信道下通过利用最大似然(ML)接收机,仍可获得满异步协作分集增益,仿真结果验证了该理论分析,仿真结果同时表明：在快衰落瑞利信道下,DLC-STC采用MMSE-DFE接收机能够获得与ML接收机相同的分集增益。

     

LDPC编码调制系统中基于反馈LLR均值的迭代解调/译码算法

该文针对LDPC码编码的BICM系统,提出一种对LDPC码译码器输出外附信息的计算方法进行改进的迭代解调/译码算法。与传统的解调/译码算法不同在于,该算法对每次BP迭代中译码器输出的各编码比特的外附LLR分别求均值后,再将其作为先验信息反馈给软解调器开始下次的迭代解调/译码。采用该方法可有效地减轻LDPC码在BP迭代过程中某些比特LLR值的振荡现象,从而使得传递给软解调器的外附信息更准确。仿真结果表明,和传统的两种迭代解调/译码算法相比,该算法能进一步提高LDPC编码BICM迭代系统的译码性能,而复杂度并无明显增加。     

瑞利信道MQAM传输误码性能数值分析——移动通信中多电平正交振幅调制方案的优化考虑(二)

分析了在含有高斯白噪声的Rayleigh衰落信道中,矩形星座图MQAM、圆形星座图MQAM的传输误码性能,给出相应的误码率计算公式,并进行计算机数值分析。为在移动通信中MQAM调制方案的优化选择提供了分析结论。     

基于FABA-SISO的时变频率选择性衰落信道CPM信号盲均衡

该文针对时变频率选择性衰落信道下高阶连续相位调制(CPM)信号盲均衡中存在的均衡性能较差、复杂度较高以及收敛速度慢等问题,从双向自适应信道均衡的角度出发,将线性调制信号均衡中使用的前后向自适应软输入软输出(FABA-SISO)算法推广,建立一种新的基于FABA-SISO的信道盲均衡方法,并结合逐幸存处理(PSP)思想和Kalman滤波,提出一种适用于高阶CPM信号的自适应盲均衡算法。该算法通过使用FABA-SISO算法,同时利用过去、现在和将来的观察数据进行Kalman滤波信道估计,有效改善了信道估计的精度,同时使用PSP算法来降低系统的复杂度,使得算法具有较好的工程应用性。仿真结果表明所提算法具有良好的盲均衡性能以及收敛性。     

宽带无线网络中的自适应编码调制技术研究

由于自适应编码调制技术在宽带无线网络中对于改善频谱利用率和增加数据速率来说是一项能力很强的技术,因此本文针对刚提出的CT-TCM技术,将其与RCPT和ARQ技术结合起来,讨论了一种新的自适应编码调制方案.并对实现该方案的一些具体细节进行了详细的阐述.