本文選題：空間光通信 + LDPC碼　； 參考：《長春理工大學(xué)》2014年碩士論文

【摘要】：空間光通信技術(shù)具有抗電磁干擾強(qiáng)、發(fā)射光束窄、方向性好、頻帶寬、成本低等一系列優(yōu)點(diǎn),越來越受到人們的重視。但是,空間光通信系統(tǒng)的性能容易受天氣狀況和環(huán)境噪聲因素的影響,使通信系統(tǒng)的誤碼率提高,極大地約束了空間光通信技術(shù)的發(fā)展和應(yīng)用。信道編碼技術(shù)可以有效的降低系統(tǒng)的誤碼率。 在差錯(cuò)控制編碼領(lǐng)域,性能非常接近香農(nóng)限(Shannon)的低密度奇偶校驗(yàn)碼(LDPC)是非常優(yōu)越的好碼,而且又具有碼長與譯碼復(fù)雜度成線性關(guān)系、硬件實(shí)現(xiàn)復(fù)雜度低,高速率譯碼能力等諸多優(yōu)點(diǎn),逐漸成為差錯(cuò)控制編碼的首選。 本文將空間光通信技術(shù)和差錯(cuò)控制編碼技術(shù)有機(jī)結(jié)合,在充分考慮空間光通信系統(tǒng)中PPM調(diào)制大氣隨機(jī)信道的特點(diǎn)和LDPC碼的優(yōu)點(diǎn)的情況下,利用FPGA硬件設(shè)計(jì)技術(shù)的發(fā)展,研究基于FPGA開放平臺(tái)上LDPC碼編解碼技術(shù)在空間光通信系統(tǒng)中的應(yīng)用。 首先,本文研究了LDPC碼的理論,主要有LDPC碼的定義、表示方式、校驗(yàn)矩陣的構(gòu)造和編譯碼原理,同時(shí)對(duì)空間光通信系統(tǒng)原理進(jìn)行了簡單介紹；其次,比較分析了LDPC碼的硬判決譯碼算法和軟判決譯碼算法,并對(duì)不同譯碼算法進(jìn)行了性能仿真分析,結(jié)果表明選擇一種合適的編譯碼方案要綜合考慮糾錯(cuò)性能和硬件實(shí)現(xiàn)復(fù)雜度之間的關(guān)系；再次,提出了基于FPGA硬件開發(fā)平臺(tái)的π旋轉(zhuǎn)LDPC碼編解碼技術(shù)在空間光通信系統(tǒng)中應(yīng)用的技術(shù)方案,并用Matlab軟件對(duì)采用PPM調(diào)制的空間光通信系統(tǒng)進(jìn)行建模和性能仿真分析,結(jié)果表明在基于PPM調(diào)制的大氣信道中,采用π旋轉(zhuǎn)碼編譯碼技術(shù)方案后的系統(tǒng)糾錯(cuò)性能有顯著提高；最后,以FPGA硬件開發(fā)平臺(tái)為基礎(chǔ),利用QuartusⅡ9.1軟件設(shè)計(jì)工具以及、Verilog DHL語言完成了π旋轉(zhuǎn)LDPC碼編碼器和譯碼器的設(shè)計(jì)和實(shí)現(xiàn),并用Modelsim6.5軟件進(jìn)行了仿真驗(yàn)證。
[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，

本文編號(hào)：2061149