A New Class of Efficient Block-Iterative Interference Cancellation Techniques for Digital Communication Receivers

A new and efficient class of nonlinear receivers is introduced for digital communication systems. These iterated-decision receivers use optimized multipass algorithms to successively cancel interference from a block of received data and generate symbol decisions whose reliability increases monotonically with each iteration. Two variants of such receivers are discussed: the iterated-decision equalizer and the iterated-decision multiuser detector. Iterated-decision equalizers, designed to equalize intersymbol interference (ISI) channels, asymptotically achieve the performance of maximum-likelihood sequence detection (MLSD), but only have a computational complexity on the order of a linear equalizer (LE). Even more importantly, unlike the decision-feedback equalizer (DFE), iterated-decision equalizers can be readily used in conjunction with error-control coding. Similarly, iterated-decision multiuser detectors, designed to cancel multiple-access interference (MAI) in typical wireless environments, approach the performance of the optimum multiuser detector in uncoded systems with a computational complexity comparable to a decorrelating detector or a linear minimum mean-square error (MMSE) multiuser detector.     

基于符号的MAP算法的Turbo编码调制系统

将TCM技术和Turbo编码相结合，提出了一种基于8PSK的Turbo TCM系统结构，并可以推广到其它多进制调制方式中，同时提出了相应的译码结构和基于符号的最大后验概率的译码算法。计算仿真表明：其性能不仅比Turbo码系统更接近Shannon限，而且提高了频带利用率，可以广泛地应用于现代移动通信系统中。     

基于Turbo码的联合迭代解调译码

依据迭代译码的基本思想,研究了联合迭代解调译码原理与方法。在此基础上,给出了基于 Turbo码的迭代解调译码技术的实现方法、接收机的结构以及最大后验概率解调的实现方法。实验和应用结果表明,采用联合迭代解调译码技术,可有效地提高系统的整体性能。     

Iterative multi-user detection and decoding for space-time block coding systems

1 Introduction Recently space–time coding (STC) techniques [1] are designed to combat fading in wireless links by utilizing multiple antenna systems, in which transmit diversity and coding gains can be exploited without sacrificing additional power and b…     

Soft-Decision Decoding of Punctured Convolutional Codes in Asynchronous-CDMA Communications Under Perfect Phase-Tracking Conditions

In this paper, the performance of punctured convolutional codes of short constraint lengths is discussed. The punctured codes are used to provide error protection to a particular user in an asynchronous CDMA system. A perfect phase reference is assumed to be available throughout this paper. A slow fading Rician channel is assumed. Maximum likelihood decoding through a Viterbi algorithm is used to decode the information symbols. Soft-decision decoding of punctured convolutional codes is considered in this paper. The upper bounds with Viterbi decoding are derived and plotted for the various punctured codes considered. The simulated results are found to agree very well with their upper and lower bounds.     

并行级联LDPC码译码迭代终止准则研究

提出了两种低复杂度的终止准则,以用于降低PCGC（并行级联Gallager码,parallel concatenated gallagercode）的译码器运算量.这两种准则通过观察边信息方差的改变情况,来判断是否终止译码器迭代.计算机仿真结果证明,这些终止准则可有效地降低译码器运算量,且不影响译码器误比特率性能.     

卫星通信协议中卷积码序列译码的计算机模拟

主要研究卫星通信协议IESS 309协议中的系统卷积码的编码及其序列译码的计算机模拟。用C语言实现了码率为1／2的36位的系统卷积码的编码，然后模拟高斯噪声信道生成一个Fano度量表，最后用Fano算法实现该卷积码的软判决序列译码，并进行了性能分析，为以后的工程应用打下一个良好的基础。     

卷积码维特比译码算法最佳反馈深度研究

卷积码可以用维特比算法作为译码算法,由于维特比译码器复杂度随着反馈深度的增长成指数倍增长,因而译码反馈深度对译码器的复杂度影响很大甚至可能无法实用,目前有些文献中仅给出了反馈深度的大致范围,但在硬件实现和性能仿真时无法确定一个具体的数值。通过在OFDM系统中运用卷积编码和维特比译码仿真分析发现,维特比译码器反馈深度为卷积码编码器存贮长度的5倍时,既可达到性能和硬件复杂度的良好折衷,又便于实际应用。     

网格编码调制在卫星高速数据传输中的应用

首先对网格编码调制(Trellis Coded Modulation,TCM)进行了系统概述,重点讨论了网格编码调制技术的基本特点、集合分割映射原理及Viterbi译码算法,并对TCM在AWGN信道中的性能进行了仿真,由此论证了网格编码调制技术在功率和带宽受限的卫星高速数据传输中的应用。     

基于单片机和PT2272的编码解码方法

以MCS 51单片机89C51和解码芯片PT2272 L4组成的编码解码器为例,介绍了解码芯片PT2272的特性,由89C51和PT2272组成的编码解码电路及其在实时控制网络中对PT2272 L4的数据通道寻址的编码,发码子程序的框图。说明这种编码解码方法的寻址空间大、速度快、可靠性高、价格低,特别适合于实时控制,有广泛的应用前景。