LTE系統(tǒng)中信道編碼的研究及Turbo碼的實(shí)現(xiàn)

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摘要 隨著現(xiàn)代通信技術(shù)的發(fā)展，用戶對高效、高可靠性數(shù)字通信系統(tǒng)的需求越來越大。因此，設(shè)計(jì)人員們紛紛開動，要在系統(tǒng)功率和傳輸帶寬有限、系統(tǒng)復(fù)雜性和成本盡可能小的條件下，實(shí)現(xiàn)信息盡可能準(zhǔn)確的傳輸。3GPP提出的LTE技術(shù)，具有系統(tǒng)傳輸延遲低、數(shù)據(jù)傳輸速率高、頻譜利用率高以及設(shè)備成本的相對低廉的優(yōu)點(diǎn)，現(xiàn)已被廣泛采用并投入運(yùn)營。雖然LTE中Turbo碼的標(biāo)準(zhǔn)已經(jīng)制定，但人們對于信道編碼的研究和Turbo碼的研究從未停止。因?yàn)樵谕ㄐ畔到y(tǒng)、尤其是當(dāng)代高速、高可靠性要求的通信系統(tǒng)中，作為能消除或降低的信息傳輸錯(cuò)誤概率的有效手段的信道編碼，其地位的重要不言而喻。
本文首先概述了LTE系統(tǒng)及其關(guān)鍵技術(shù)，對MIMO技術(shù)和OFDM技術(shù)作了簡要介紹，同時(shí)，給出LTE選用Turbo碼作為數(shù)據(jù)信道編碼的理由；然后，詳細(xì)解說了信道編碼和Turbo碼的原理，包括數(shù)字通信系統(tǒng)模型的分析、信道編碼的原理與重要性以及Turbo碼的原理與優(yōu)勢，對上文LTE對Turbo碼的采用給出原理上的支持；其次，詳細(xì)說明了Turbo譯碼的常用算法，包括MAP算法及其演化算法（包括Log-MAP算法和Max-Log-MAP算法）和SOVA算法，并對各譯碼算法性能進(jìn)行了比較，同時(shí)對各算法性能的影響因素做出分析對比，得出算法怎樣設(shè)計(jì)能獲得最大效益的結(jié)論；
最后，在系統(tǒng)仿真部分，先按照一般FPGA設(shè)計(jì)的流程，依據(jù)Turbo碼編譯碼器的原理，設(shè)計(jì)思路，選擇適當(dāng)?shù)墓ぞ哕浖≦uratus II）和編程語言（Verilog HDL），通過對RSC模塊、交織器、反交織器等模塊的設(shè)計(jì)、編寫與綜合，并在Modelsim上調(diào)試仿真運(yùn)行，通過波形觀察結(jié)果，并驗(yàn)證，最終實(shí)現(xiàn)Turbo碼編碼器和譯碼器的設(shè)計(jì)，驗(yàn)證其可行性。
關(guān)鍵字 LTE 信道編碼 Turbo碼 MAP SOVA FPGA

Research of LTE systems channel coding and implementation of Turbo Codes
Abstract With the development of modern communication technology, user's demand for efficient, high-reliability digital communication systems is growing. Therefore, the designers did all they can to achieve accurate transmission of information with the limitation of system power and bandwidth when the system complexity and cost should be as little as possible. The LTE technology 3GPP presents, has been widely adopted and put into operation, with the advantage of low system transmission delay, high data transfer rate, high spectrum efficiency and relatively low equipment cost. Although the standard in LTE Turbo codes have been developed, the study and research of channel coding and Turbo codes never stopped. For the channel coding plays an important role as an effective means to eliminate or reduce the transmission error probability of the information in the communication system, especially in modern high-speed, high-reliability communication system.
This paper begins with an overview of the LTE system and its key technology, MIMO technology and the OFDM technology, are briefly introduced, and a reason is given for the selection of Turbo codes as the data channel coding code in the LTE. Then, a detailed explanation of the principle of channel coding and Turbo codes is given, including the analysis of digital communication system model and the importance of the principle of channel coding and the principles and advantages of turbo codes ,which will strongly support the chosen of adoption of turbo codes in the LTE system as proposed above. After that, the paper details the commonly used algorithms for turbo decoding, including MAP algorithm and its evolutionary algorithms(Log-MAP algorithm and MAX-Log-MAP algorithm), and the SOVA algorithm. It also compares the performance of various decoding algorithms, and the impact of various factors on the performance of the algorithms. Then, a conclusion is made on how to get the largest advantage.
Finally, in the system simulation section, first as a general FPGA design process, according to the turbo coding principles, we design ideas, select the appropriate tool (Quartus II) and the programming languages (Verilog HDL), and through the RSC module, interleaver anti-interleaver design modules, the preparation and synthesis, simulation and debug run on Modelsim, through waveform observation and verification, and ultimately realize the design of turbo code encoder and decoder.
Keyword LTE channel coding turbo codes MAP SOVA FPGA

目錄
第一章 概論 1
1.1 通信系統(tǒng)的發(fā)展與信道編碼的研究意義 1
1.1.1 通信系統(tǒng)的發(fā)展 1
1.1.2 信道編碼的研究意義 1
1.2 信道編碼的發(fā)展歷程和Turbo碼研究現(xiàn)狀以及發(fā)展趨勢 1
1.2.1 信道編碼的發(fā)展歷程 1
1.2.2 Turbo碼的研究現(xiàn)狀及發(fā)展趨勢 1
1.3 本文的研究內(nèi)容 1
第二章 LTE系統(tǒng)中信道編碼的研究 1
2.1 LTE系統(tǒng) 1
2.1.1 LTE系統(tǒng)簡介 1
2.1.2 LTE系統(tǒng)的關(guān)鍵技術(shù) 1
2.2 信道編碼 1
2.2.1 信道編碼簡介 1
2.2.2 Turbo碼 1
第三章 LTE系統(tǒng)譯碼算法的分析 1
3.1 Turbo譯碼的常用算法 1
3.1.1 MAP族算法 1
3.1.2 SOVA算法 1
3.2 各算法性能對比 1
3.3 Turbo碼算法影響因素 1
3.3.1 分量碼 1
3.3.2 迭代次數(shù) 1
3.3.3 信息序列長度 1
第四章 LTE系統(tǒng)中Turbo碼的實(shí)現(xiàn) 1
4.1 前期準(zhǔn)備 1
4.1.1 設(shè)計(jì)思路 1
4.1.2 工具軟件簡介 1
4.1.3 編程語言 1
4.2 編碼器設(shè)計(jì) 1
4.2.1 整體設(shè)計(jì) 1
4.2.2 RSC分量編碼器 ..