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.     

基于类语言模型的中文机构名称自动识别

提出了一种基于类语言模型的中文机构名称自动识别方法,将分词和机构名称自动识别有机地结合起来。在机构名称识别的类语言模型中采用等级结构,使得嵌套有人名、地名等实体的机构名称能够较好地识别出来。在实验过程中,逐步增加实验条件,依次加入启发信息、缓存模型和机构名缩写处理,使得实验结果显著提高。在开放测试中,中文机构名称最终识别的查准率和查全率分别为85.47%和72.81%。     

基于软件无线电的非相干接收机研究

本文根据软件无线电思想,在通用的平台上接收GM鄄SK、QPSK两个不同的调制的信号,对接收机各个部分的算法进行分析,如匹配滤波器的算法,信道参数估计,同步估计,信道均衡等,文章最后分析了软件无线电接收机应采用的硬件结构。     

W-CDMA系统中维特比译码器的FPGA实现

W-CDMA系统中采用约束长度为9的卷积编码作为信道编码方案之一,维特比译码器是被一种人们广泛采用的卷积编码的解码器;本文通过分析卷积编码及维特比译码的过程,介绍一种适合WCDMA系统中软判决维特比译码器实现的硬件结构。     

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。