基于FPGA的LDPC编解码技术研究

发布时间：2018-06-24 10:02

  本文选题：空间光通信 + LDPC码　； 参考：《长春理工大学》2014年硕士论文

【摘要】：空间光通信技术具有抗电磁干扰强、发射光束窄、方向性好、频带宽、成本低等一系列优点,越来越受到人们的重视。但是,空间光通信系统的性能容易受天气状况和环境噪声因素的影响,使通信系统的误码率提高,极大地约束了空间光通信技术的发展和应用。信道编码技术可以有效的降低系统的误码率。 在差错控制编码领域,性能非常接近香农限(Shannon)的低密度奇偶校验码(LDPC)是非常优越的好码,而且又具有码长与译码复杂度成线性关系、硬件实现复杂度低,高速率译码能力等诸多优点,逐渐成为差错控制编码的首选。 本文将空间光通信技术和差错控制编码技术有机结合,在充分考虑空间光通信系统中PPM调制大气随机信道的特点和LDPC码的优点的情况下,利用FPGA硬件设计技术的发展,研究基于FPGA开放平台上LDPC码编解码技术在空间光通信系统中的应用。 首先,本文研究了LDPC码的理论,主要有LDPC码的定义、表示方式、校验矩阵的构造和编译码原理,同时对空间光通信系统原理进行了简单介绍；其次,比较分析了LDPC码的硬判决译码算法和软判决译码算法,并对不同译码算法进行了性能仿真分析,结果表明选择一种合适的编译码方案要综合考虑纠错性能和硬件实现复杂度之间的关系；再次,提出了基于FPGA硬件开发平台的π旋转LDPC码编解码技术在空间光通信系统中应用的技术方案,并用Matlab软件对采用PPM调制的空间光通信系统进行建模和性能仿真分析,结果表明在基于PPM调制的大气信道中,采用π旋转码编译码技术方案后的系统纠错性能有显著提高；最后,以FPGA硬件开发平台为基础,利用QuartusⅡ9.1软件设计工具以及、Verilog DHL语言完成了π旋转LDPC码编码器和译码器的设计和实现,并用Modelsim6.5软件进行了仿真验证。
[Abstract]:Space optical communication technology has a series of advantages, such as strong electromagnetic interference resistance, narrow beam emission, good directivity, frequency bandwidth, low cost and so on, and has attracted more and more attention. However, the performance of space optical communication system is easy to be affected by weather conditions and environmental noise factors, which greatly restricts the development and application of space optical communication technology. The channel coding technique can effectively reduce the bit error rate (BER) of the system. In the field of error control coding, low density parity check code (LDPC) with performance close to Shannon limit (LPC) is a very good code, and has a linear relationship between code length and decoding complexity, so the hardware implementation complexity is low. High rate decoding ability has gradually become the first choice of error control coding. In this paper, the space optical communication technology and error control coding technology are organically combined, and the characteristics of PPM modulated atmospheric random channel and the advantages of LDPC code are fully considered in space optical communication system, and the development of FPGA hardware design technology is used. The application of LDPC coding and decoding technology in space optical communication system based on FPGA open platform is studied. Firstly, this paper studies the theory of LDPC codes, including the definition of LDPC codes, the representation of LDPC codes, the construction of check matrices and the encoding and decoding principles. At the same time, the principle of spatial optical communication system is briefly introduced. The hard decision decoding algorithm and soft decision decoding algorithm of LDPC code are compared and analyzed, and the performance of different decoding algorithms is simulated. The results show that the relationship between error correction performance and hardware implementation complexity should be considered in order to select a suitable encoding and decoding scheme. The technology scheme of 蟺 rotation LDPC coding and decoding technology based on FPGA hardware development platform is put forward in space optical communication system. The modeling and performance simulation analysis of PPM modulated space optical communication system is carried out with Matlab software. The results show that in the PPM modulated atmospheric channel, the error correction performance of the system based on the 蟺 rotary code coding and decoding scheme is improved significantly. Finally, based on the FPGA hardware development platform, the error correction performance of the system is improved. Using Quartus 鈪，

本文编号：2061149