低信噪比条件下Turbo编译码算法研究和性能评估.pdf

_______________________________________________________________________________ 低信噪比条件下Turbo 编译码算法研究及性能评估* 肖扬 黄和斌 北京交通大学 信息科学研究所，北京 100044 摘 要：由于Turbo 码优异的纠错性能，CDMA2000 与WCDMA 将其作为候选的信道编码方案。本文研 究了Turbo 码的基本原理和编解码算法，在此基础上对Turbo 码编解码系统进行了低信噪比环境下的计算 机仿真。本文设计的Turbo 码编解码采用了伪随机交织器，它将低重量输入信息序列产生低重量编码序列 的关系打破，提高了Turbo 码编解码系统性能。系统仿真结果及分析表明有译码迭代次数、RSC 分量码， 交织器大小与交织器图等几个因素会影响Turbo 码编解码系统性能。 关键词 无线通信；Turbo 码；LOG-MAP 算法；迭代译码 中文分类号：TN914.3 文献标识码：A Analysis and Evaluation for Turbo Coding and Decoding Arithmetic Based on Low SNR XIAO Yang HUANG He-bin Institute of Information Science, Beijing Jiaotong University, Beijing 100044, China E-mail: yxiao@ Abstract: Due to their excellent performance of error correcting, turbo codes have selected channel coding schemes for CDMA2000 and WCDMA. This paper studies the basic principle of turbo codes and their coding and decoding algorithms, on the basis of which the computer simulation are made in the environment of lower SNR. Additionally, the interleaver we designed for the Turbo encoder and decoder system adopts the pseudo-random interleaver, it breaks the relation that low weigh input sequence produces low weigh code sequence, and improves the performance of the Turbo encoder and decoder systems. Moreover, our simulation results and analysis for the Turbo code systems show that some factors, such as the number of the iterations of the decoder, RSC codes, the length of interleaver, and the interleaver map, will influence the performance of Turbo encoder and decoder systems. Key words: wireless communications; Turbo codes; LOG-MAP algorithm; Iterative decoding 0 引言 Turbo码自 1993 年被提出以来[1]，就以其优异的纠错性能而受关注 [2-7] 。Turbo码是用短码去构造等 效意义的长码，以达到长码的纠错