本文關(guān)鍵詞：基于Turbo同步的聯(lián)合解調(diào)譯碼技術(shù)研究　出處：《西安電子科技大學》2014年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 符號定時 載波同步 Turbo同步 聯(lián)合解調(diào)譯碼

【摘要】：采用LDPC碼、Turbo碼的現(xiàn)代通信系統(tǒng)可以工作在距離Shannon限很近的信噪比區(qū)域,但是該結(jié)論是建立在解調(diào)器能夠完美地進行載波頻率、相位與定時恢復的假設(shè)上的。在低信噪比下,傳統(tǒng)的解調(diào)與譯碼分離的傳輸方案不能充分發(fā)揮現(xiàn)代信道編碼方法的優(yōu)勢,較大的同步誤差會導致Turbo/LDPC碼具有很差的性能,從而使得整個系統(tǒng)仍然工作在距離Shannon限較遠的區(qū)域。研究表明,基于Turbo原理的迭代載波相位與符號定時恢復(也稱為Turbo同步)技術(shù)為此提供了一條有效的解決方案。本文結(jié)合中國電子科技集團公司第54研究所的合作課題,利用Shannon極限碼的結(jié)構(gòu)特點,提出了一個基于Turbo同步技術(shù)的聯(lián)合解調(diào)譯碼技術(shù)方案,極大地改善了低信噪比區(qū)域的同步性能。本文的具體工作成果主要包括:1.針對僅有碼輔助同步的通信系統(tǒng),分別給出了對應的迭代符號定時與載波同步算法,然后設(shè)計了一個基于Turbo同步的聯(lián)合解調(diào)譯碼技術(shù)方案,將定時恢復和載波同步嵌入到迭代譯碼過程,并進行仿真實現(xiàn)。2.針對具有獨特碼輔助的衛(wèi)星通信系統(tǒng),分別給出了對應的非迭代符號定時與載波同步算法,然后利用碼輔助Turbo同步的思想,提出使用VV(Viterbi A JViterbi A M)算法與加窗搜索算法相結(jié)合的方式來恢復頻偏,將頻偏、初相估計和信道譯碼構(gòu)成一個Turbo迭代,并進行了分析仿真。仿真結(jié)果表明,所提出的Turbo同步方案與接收端完全已知載波相位和完美定時的系統(tǒng)性能相差在0.5d B之內(nèi),且比解調(diào)、譯碼分離形式的解調(diào)器性能提高1d B以上,從而極大地改善了低信噪比區(qū)的同步性能,使得LDPC、Turbo等Shannon極限碼得以在實際系統(tǒng)中獲得充分利用。
[Abstract]:The modern communication system using LDPC code can work in the signal-to-noise ratio (SNR) region which is very close to the Shannon limit, but the conclusion is that the demodulator can carry out the carrier frequency perfectly. Under the condition of low SNR, the traditional transmission scheme of demodulation and decoding can not give full play to the advantages of modern channel coding methods. Large synchronization error will lead to poor performance of Turbo/LDPC code, which makes the whole system still work in the region far from the Shannon limit. Iterative Carrier Phase and symbol timing recovery based on Turbo principle (also known as Turbo synchronization). Technology provides an effective solution for this. This paper combined with the China Electronic Science and Technology Corporation of the 54th Institute of cooperation. Based on the structural characteristics of Shannon limit codes, a joint demodulation and decoding scheme based on Turbo synchronization technology is proposed. The performance of synchronization in low signal-to-noise ratio region is greatly improved. The main achievements of this paper include: 1. For only code-assisted synchronization communication system. The corresponding iterative symbol timing and carrier synchronization algorithms are given respectively. Then a joint demodulation and decoding scheme based on Turbo synchronization is designed to embed timing recovery and carrier synchronization into the iterative decoding process. The corresponding non-iterative symbol timing and carrier synchronization algorithms are given for the satellite communication system with unique code-assisted. Then the idea of code-assisted Turbo synchronization is used. In this paper, the method of combining VV(Viterbi A JViterbi A M) algorithm with windowed search algorithm is proposed to recover the frequency offset. The initial phase estimation and channel decoding constitute a Turbo iteration and are analyzed and simulated. The simulation results show that. The performance of the proposed Turbo synchronization scheme is less than 0.5 dB with the receiver fully known carrier phase and perfect timing, and is demodulated. The performance of the demodulator in decode separation form is improved by more than 1dB, which greatly improves the synchronization performance in the low SNR region and makes the LDPC. Shannon limit codes such as Turbo can be fully utilized in practical systems.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN911.22

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