本文關(guān)鍵詞： 星基增強(qiáng)系統(tǒng) 鏈路預(yù)算 QC-LDPC碼 信號(hào)捕獲 系統(tǒng)同步　出處：《西安電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：作為全球衛(wèi)星導(dǎo)航系統(tǒng)(Global Navigation Satellite System,GNSS)的組成部分,星基增強(qiáng)系統(tǒng)(Satellite-Based Augmentation System,SBAS)由于其重要的作用而受到國(guó)內(nèi)外學(xué)者的廣泛關(guān)注。SBAS能夠?yàn)橛脩籼峁╊~外的信息,從而增強(qiáng)定位信號(hào)、導(dǎo)航信號(hào)和授時(shí)信號(hào)質(zhì)量,并能提升導(dǎo)航系統(tǒng)的定位精度、可用性、連續(xù)性和完好性。在星基增強(qiáng)系統(tǒng)中,增強(qiáng)信息經(jīng)地星-星地傳輸鏈路傳輸至用戶接收機(jī),該傳輸鏈路是否有效、可靠,直接決定了該增強(qiáng)系統(tǒng)的性能。本文對(duì)星基增強(qiáng)系統(tǒng)中的地星-星地鏈路信息傳輸技術(shù)進(jìn)行了系統(tǒng)的研究,主要工作及所取得的研究成果如下:1.對(duì)星基增強(qiáng)系統(tǒng)及其傳輸鏈路進(jìn)行了研究。通過研究已有的星基增強(qiáng)系統(tǒng)及其傳輸鏈路結(jié)構(gòu),給出了系統(tǒng)設(shè)計(jì)所需考慮的參數(shù);通過鏈路預(yù)算,獲得系統(tǒng)鏈路可用的最低比特信噪比,并提出了一種基于高效編譯碼的系統(tǒng)傳輸鏈路方案。理論分析表明:該方案可滿足較高的信息傳輸速率和較低的系統(tǒng)誤碼率要求。2.對(duì)準(zhǔn)循環(huán)低密度奇偶校驗(yàn)碼(QC-LDPC)進(jìn)行了研究。介紹了QC-LDPC碼的校驗(yàn)矩陣構(gòu)造方法和編譯碼方法,重點(diǎn)探討了基于循環(huán)置換矩陣的構(gòu)造方法和對(duì)數(shù)域BP譯碼算法;針對(duì)系統(tǒng)高信息傳輸速率和低誤碼率的要求,設(shè)計(jì)了一種1/2碼率的(2488,3,6)QC-LDPC碼。仿真結(jié)果表明:該碼在10-7誤碼率水平可提供約8.8dB的編碼增益。3.對(duì)星基增強(qiáng)系統(tǒng)的接收端關(guān)鍵技術(shù)進(jìn)行了研究。詳細(xì)比較了常用的信號(hào)捕獲算法,針對(duì)本系統(tǒng)的信號(hào)特點(diǎn)提出了一種基于串行搜索和非相干累加的弱信號(hào)捕獲方案;研究了鎖相環(huán)的基本原理,并給出了基于Costas環(huán)的載波跟蹤方案和基于DLL環(huán)的碼跟蹤方案;采用巴克碼滑動(dòng)相關(guān)法實(shí)現(xiàn)了系統(tǒng)的位同步和幀同步;基于Matlab仿真平臺(tái),搭建了傳輸鏈路仿真系統(tǒng),給出了整體仿真流程圖及模塊間的銜接關(guān)系,并進(jìn)行了性能仿真分析。
[Abstract]:As an integral part of Global Navigation Satellite system Navigation, the satellite-based Augmentation system SBASs has attracted extensive attention from scholars at home and abroad for its important role. SBAS can provide additional information to users and thus enhance positioning signals. The quality of navigation signals and timing signals, and the improvement of positioning accuracy, availability, continuity and integrity of navigation systems. In space-based augmentation systems, enhancement information is transmitted to the user receiver via the earth-satellite transmission link, Whether the transmission link is effective and reliable directly determines the performance of the enhanced system. The main work and research results are as follows: 1. The space-based enhancement system and its transmission link are studied. By studying the existing space-based enhancement system and its transmission link structure, the parameters that need to be considered in the design of the system are given. Through the link budget, the minimum bit signal-to-noise ratio (SNR) available for the system link is obtained, A system transmission link scheme based on efficient encoding and decoding is proposed. Theoretical analysis shows that the scheme can meet the requirements of higher transmission rate and lower bit error rate (BER) of the system. QC-LDPC is used to align the cyclic low density parity check code. The construction method of check matrix and the method of encoding and decoding of QC-LDPC code are introduced. The construction method based on cyclic permutation matrix and logarithmic domain BP decoding algorithm are discussed, and the requirements of high information transmission rate and low bit error rate of the system are discussed. A 1/2 bit rate QC-LDPC code is designed. The simulation results show that the code can provide a coding gain of about 8.8 dB at the 10-7 bit error rate level. The key technologies of the receiver of the space-based enhancement system are studied, and the commonly used signal acquisition algorithms are compared in detail. According to the signal characteristics of this system, a weak signal acquisition scheme based on serial search and incoherent accumulation is proposed, and the basic principle of phase-locked loop is studied, and the carrier tracking scheme based on Costas loop and the code tracking scheme based on DLL loop are given. Buck code sliding correlation method is used to realize bit synchronization and frame synchronization, and based on Matlab simulation platform, the transmission link simulation system is built, and the overall simulation flow chart and the connection relationship between modules are given, and the performance simulation analysis is carried out.
【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
【分類號(hào)】：TN967.1

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本文編號(hào)：1534388