發(fā)布時(shí)間：2018-04-16 18:45

  本文選題：信道編碼 + 準(zhǔn)循環(huán)LDPC碼��； 參考：《西安電子科技大學(xué)》2014年碩士論文

【摘要】：目前科學(xué)技術(shù)發(fā)展迅猛,其中高清晰電視、視頻會(huì)議、遠(yuǎn)程監(jiān)控以及遙感成像等技術(shù)得到廣泛應(yīng)用,人們生活中的信息交流已經(jīng)主要依靠于多媒體通信。而通信系統(tǒng)往往會(huì)受到噪聲干擾,使得無(wú)線(xiàn)信道中傳輸?shù)膱D像質(zhì)量大大下降,尤其是深空通信有著超遠(yuǎn)的傳輸距離、超復(fù)雜的傳輸環(huán)境以及自身設(shè)備及能源嚴(yán)格受限等特性,對(duì)信道糾錯(cuò)編碼等關(guān)鍵技術(shù)提出了較高的要求,因此學(xué)習(xí)研究信道編碼的意義深遠(yuǎn)。隨著稀疏圖碼與譯碼中迭代理論的研究與實(shí)現(xiàn),LDPC(低密度奇偶校驗(yàn)碼)漸漸受到普遍關(guān)注,它性能逼近香農(nóng)限、實(shí)現(xiàn)復(fù)雜度低、譯碼算法可并行且描述簡(jiǎn)單,因此LDPC碼已經(jīng)應(yīng)用于各種新的通信標(biāo)準(zhǔn)。其中,有著獨(dú)特奇偶校驗(yàn)矩陣結(jié)構(gòu)的準(zhǔn)循環(huán)LDPC碼,能夠?qū)崿F(xiàn)具有線(xiàn)性復(fù)雜度的編碼,是一種得到了廣泛應(yīng)用的結(jié)構(gòu)化LDPC碼。1)本文對(duì)于基于歐式有限幾何方法構(gòu)造的準(zhǔn)循環(huán)LDPC碼進(jìn)行了深入研究,設(shè)計(jì)了CCSDS標(biāo)準(zhǔn)的基礎(chǔ)(8176,7154)準(zhǔn)循環(huán)LDPC碼,并進(jìn)行了實(shí)驗(yàn)仿真與分析。實(shí)驗(yàn)結(jié)果說(shuō)明,與對(duì)應(yīng)的隨機(jī)LDPC碼相比,合理構(gòu)造的準(zhǔn)循環(huán)LDPC碼在編譯碼復(fù)雜度大大降低的基礎(chǔ)上基本沒(méi)有損失性能。另外,對(duì)于迭代次數(shù)對(duì)譯碼性能的影響做了基礎(chǔ)研究。2)由于準(zhǔn)循環(huán)LDPC碼被廣泛應(yīng)用于各種實(shí)際工程,高效譯碼算法的重要性便體現(xiàn)出來(lái)。本文在研究了BP算法、LLR-BP算法、MS算法等基本譯碼方法的基礎(chǔ)上深入探討并實(shí)現(xiàn)了SBP算法以及其改進(jìn)算法的實(shí)驗(yàn)仿真。結(jié)果說(shuō)明,改進(jìn)的SBP算法不僅在譯碼性能上略占優(yōu)勢(shì),還降低了運(yùn)算復(fù)雜度,提高了收斂速度。最后分析了譯碼錯(cuò)誤產(chǎn)生的原因并綜合考慮了系統(tǒng)性能的需求以及硬件資源,提出了一種改進(jìn)的多點(diǎn)最小和算法并進(jìn)行了實(shí)驗(yàn)仿真。該算法在很少增加復(fù)雜度的前提下,提高了譯碼算法的性能,減少了平均迭代次數(shù),因此適合于對(duì)誤碼率性能和譯碼速度均有嚴(yán)格要求的高吞吐量LDPC碼譯碼器的使用。3)最后針對(duì)CCSDS庫(kù)中遙感圖像的傳輸問(wèn)題,提出了一種基于LDPC碼的等差錯(cuò)保護(hù)遙感圖像傳輸方案。此方案對(duì)原始遙感圖像先進(jìn)行小波變換分析,再根據(jù)嵌入式分塊的方法進(jìn)行信源編碼。信道編碼則運(yùn)用基于LDPC碼的聯(lián)合編碼來(lái)對(duì)嵌入式分塊編碼過(guò)后的輸出碼流進(jìn)行同等程度的保護(hù),使得碼流的抗干擾能力得到提高。實(shí)驗(yàn)結(jié)果說(shuō)明,相比于傳統(tǒng)的RS、Tornado碼,遙感圖像的傳輸在此方案中更為可靠。最后本文總結(jié)了以上研究?jī)?nèi)容,并且針對(duì)準(zhǔn)循環(huán)LDPC的編譯碼均提出了改進(jìn)的方向。
[Abstract]:With the rapid development of science and technology, high-definition television, video conferencing, remote monitoring and remote sensing imaging are widely used. The communication of information in people's lives has mainly depended on multimedia communication.However, the communication system is often disturbed by noise, which makes the image quality in wireless channel decline greatly. Especially, the deep space communication has the characteristics of ultra-long transmission distance, ultra-complex transmission environment, strict limitation of its own equipment and energy, and so on.The key technologies such as channel error correction coding are required, so it is of great significance to study channel coding.With the research and implementation of iterative theory in sparse graph code and decoding, LDPC (low density parity check code) has been paid more and more attention. Its performance is close to Shannon limit, the complexity of implementation is low, the decoding algorithm can be parallel and simple to describe.Therefore, LDPC codes have been applied to various new communication standards.Among them, quasi-cyclic LDPC codes with unique parity check matrix structure can realize coding with linear complexity.It is a widely used structured LDPC code. 1) in this paper, the quasi-cyclic LDPC codes based on the Euclidean finite geometry method are studied in depth, and the quasi-cyclic LDPC codes based on the CCSDS standard are designed, and the experimental simulation and analysis are carried out.The experimental results show that compared with the corresponding random LDPC codes, the reasonably constructed quasi-cyclic LDPC codes have no loss of performance on the basis of greatly reducing the complexity of encoding and decoding.In addition, the influence of iteration times on decoding performance is studied. 2) because quasi-cyclic LDPC codes are widely used in various practical projects, the importance of efficient decoding algorithm is reflected.Based on the study of the basic decoding methods such as the BP algorithm and the LLR-BP algorithm and MS algorithm, this paper discusses and implements the SBP algorithm and the experimental simulation of its improved algorithm.The results show that the improved SBP algorithm not only has a slight advantage in decoding performance, but also reduces the computational complexity and improves the convergence speed.Finally, the causes of decoding errors are analyzed, and the requirements of system performance and hardware resources are considered synthetically. An improved multi-point minimum sum algorithm is proposed and the experimental simulation is carried out.The algorithm improves the performance of the decoding algorithm and reduces the average number of iterations without increasing the complexity.Therefore, it is suitable for high throughput LDPC decoder with strict performance and decoding speed. Finally, an equal-error protection remote sensing image transmission scheme based on LDPC code is proposed to solve the problem of remote sensing image transmission in CCSDS library.In this scheme, the original remote sensing image is analyzed by wavelet transform, and then the source coding is carried out according to the embedded block method.Channel coding uses joint coding based on LDPC code to protect the output bitstream after embedded block coding to the same degree, so that the anti-jamming ability of bitstream is improved.The experimental results show that the transmission of remote sensing images is more reliable than that of the traditional RSU Tornado code.Finally, this paper summarizes the above research contents, and proposes the direction to improve the encoding and decoding of quasi-cyclic LDPC.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TN911.22

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 陳孫陽(yáng);陳穎琪;王慈;;視頻傳輸不等差錯(cuò)保護(hù)方案設(shè)計(jì)[J];電視技術(shù);2010年06期

2 溫明才;劉峰;;基于噴泉碼的不等差錯(cuò)保護(hù)技術(shù)實(shí)現(xiàn)[J];計(jì)算機(jī)技術(shù)與發(fā)展;2011年04期

3 王晶;曹冠朋;;具有不等差錯(cuò)保護(hù)性能的新型噴泉碼方案[J];信息技術(shù);2013年06期

4 朱瑩瑩;王嘉;;圖像通信中的不等差錯(cuò)保護(hù)技術(shù)[J];電視技術(shù);2006年09期

5 王，

本文編號(hào)：1760145