【作者】 姚中华；

【导师】 黄建国；

【作者基本信息】 西北工业大学 ， 通信与信息系统， 2006， 硕士

【摘要】 海洋水声信道是一种极其复杂多变的时-空-频变信道，信道通带窄、多径干扰强、信号衰落严重是水声通信中信息高速可靠传输的主要障碍。因此如何在水声信道中高速可靠地传输数据，成为世界性的重要研究课题。水声通信除了采用先进的调制解调、信道均衡等技术以外，还必须采用具有很好纠错性能的纠错码来进行差错控制，进一步降低误码率，保证信息传输的可靠性。串行级连码是一种较好接近香农限的渐近好码，它是由两个确定的短码来构造长码，在不显著增加编译码复杂度和运算量的情况下，能较大提高纠错性能，具有很好地纠正突发错误、随机错误和两者共同构成的组合性错误的能力。本文根据对水声信道特性、信道产生误码的统计规律和特点、水声通信系统的性能指标要求，深入研究了串行级连码的构成、原理和性能，研究了交织器对突发错误的处理能力，提出了一种适用于水声通信的差错控制编码方法，通过仿真分析和实验验证表明该方法实用、可行。 全文的主要工作和研究成果包括以下几个方面： 1．研究了水声信道的特性和信道产生误码的统计规律和特点，研究表明：水声信道是一个随机错误和突发错误同时存在、且以密集性突发错误为主的记忆信道，这为水声数字通信系统中纠错码的设计提供了理论基础。 2．研究了RS码、卷积码及由此组成的串行级连码的原理、性能和具体编译码算法，研究表明：RS码具有很强的抗突发错误的能力，卷积码可充分利用码字之间的相关性，相当于等效地增加了码长，且卷积码采用维特比软判决译码比硬判决译码可获得2dB左右的编码增益，它们都具有较好的纠错性能。 3．根据水声信道的特性，研究了串行级连码内码、外码的选取原则，串行级连码的内码选用具有软判决最大似然译码算法的卷积码，能获得一定的编码增益，外码选取具有较强纠突发错误能力的RS码，用以克服内码错译或信道所产生的突发错误。通过对采用不同组合级连码的性能仿真及分析可得出：RS码和卷积码的级连是用于水声通信的性能很好的串行级连码。 4．研究了不同交织器、交织参数对突发错误的处理能力、如何设计交织器在串行级连码中的位置和选用何种交织器才能更好地离散突发错误，研究表明：交织器的应用主要用以解决水声信道产生的突发差错误码，随机交织器能够提供最大程度的应变能力，能最大限度地适用于水声信道，改善突发错误对纠错码性能的影响。 5．提出了一种适用于水声通信中的串行级连码结合随机交织器的差错控制更多还原

【Abstract】 Ocean channel is such a complex environment that it varies in space, time and frequency. Narrow band, multipath and fading are the three main obstacles in reliable high data rate communication. How to transmit information reliably and in high data rate in underwater environment is a hot topic. Besides advanced modulation and demodulation and channel equalization techniques etc., underwater acoustic communication must use error-correcting coding whose capability is good to ensure the reliability of information transmission and reduce bit error rate. The serial concatenated code which contains two short codes is an excellent channel code whose efficiency is closed to Shannon bounds. It has good performance of correcting random and burst error and combined error with random and burst error without adding coding and computing complexity. In this paper, according to the characteristics of underwater acoustic channel, statistical feature, characteristics of channel error and the performance requirement of communication system, the principle and structure and capability of serial concatenated code are studied in detail. The capability which interleaver deal with burst error is studied, an error-correcting coding applied in underwater acoustic communication is built up. The method is verified to be reliable and applicable by simulation and lake experiments.Main research and achievements are summarized as follows:1. The characteristics of underwater acoustic channel, statistical feature and characteristics of channel error are studied. The study show that underwater acoustic channel is a memorial channel in which random errors and burst errors occur simultaneously and dense burst errors predominate in most of time.This gives the theory foundation of how to design error-correcting code in the underwater acoustic communication system.2. The principle and performance and arithmetic of coding and decoding of RS code and convolutional code and serial RS concatenated convolutional code are studied. The results show that RS code has the ability of dealing with burst errors and convolutional code can use relativity of codes, so the length of coding increase comparatively and Viterbi soft-decision decoding can obtain 2dB coding gain than hard-decision decoding.3. According to the characteristics of underwater acoustic channel, the principle更多还原