本文選題：下行同步 + 正交頻分復用��； 參考：《武漢郵電科學研究院》2017年碩士論文

【摘要】：LTE下行同步技術(shù)是每一個移動設(shè)備接入無線網(wǎng)絡(luò)的第一步,無線終端必須通過小區(qū)搜索來接收到廣播信道中的目標小區(qū)標識,獲得時間和頻率同步。[1]對下行同步過程的研究對于整個系統(tǒng)來說十分關(guān)鍵,可以通過對接入算法的研究來提升終端的接入速度,提高內(nèi)存的利用效率。因此,對下行同步算法的研究具有重要的應(yīng)用價值。本文重點研究了LTE的同步過程和傳統(tǒng)的算法,分析得出了幾個重要的特點,如由不同的根序列生成的主同步信號中,存在著實部相同,虛部互為相反數(shù)的特點。在m序列中,總結(jié)出m"序列始終小于m#序列,以及小區(qū)組表示和他們之間的算數(shù)關(guān)系等。結(jié)合以上發(fā)現(xiàn)的重要特點,本文對算法進行了改進優(yōu)化,實現(xiàn)過程中使用了改進的基于互相關(guān)算法實現(xiàn)主同步信號同步,然后根據(jù)主同步信號進行定時同步和ML算法實現(xiàn)頻偏估計,基于循環(huán)前綴長度假設(shè)算法確定所使用的循環(huán)前綴類型,以及使用基于奇偶序列的最大m相關(guān)值實現(xiàn)輔同步信號同步算法。解決了下行同步過程中避免進行不必要的重復的大型即時運算,并優(yōu)化了消耗的本地存儲資源,加快下行同步速度,提高終端接入性能。本文使用LTE系統(tǒng)級仿真平臺,對改進的算法進行了仿真,仿真實驗的結(jié)果表示,在信噪比較低的情況下,PSS的同步性能與傳統(tǒng)算法相比,性能相差無幾,但算法運算速度有所提高。SSS的基于奇偶序列的最大m相關(guān)值在信噪比不高的情況下,同步正確率優(yōu)于傳統(tǒng)算法,且占用內(nèi)存大量減少;當信噪比足夠大時,算法正確率一致。因此,本文提出的改進后的算法能夠滿足需求。
[Abstract]:The LTE downlink synchronization technology is the first step for every mobile device to access the wireless network. The wireless terminal must receive the target cell identification in the broadcast channel through cell search. [1] the study of downlink synchronization is very important for the whole system, which can improve the access speed of terminals and improve the efficiency of memory utilization through the research of access algorithm. Therefore, the research of downlink synchronization algorithm has important application value. In this paper, the synchronization process and the traditional algorithm of LTE are studied, and several important characteristics are obtained. For example, in the main synchronous signal generated by different root sequences, the real part is the same and the imaginary part is the opposite number. In m sequence, we conclude that m "sequence is always smaller than m# sequence, and cell group representation and their arithmetic relation." Combined with the important features of the above discovery, the algorithm is improved and optimized in this paper. The improved cross-correlation algorithm is used to realize the synchronization of the main synchronous signal. Then the frequency offset is estimated according to the timing synchronization of the main synchronization signal and the ML algorithm, and the type of cyclic prefix is determined based on the cyclic prefix length assumption algorithm. And using the maximum m correlation value based on parity sequence to realize the synchronization algorithm of auxiliary synchronization signal. It solves the problem of avoiding unnecessary repeated large-scale real-time operations in the process of downlink synchronization, optimizes the local storage resources consumed, speeds up the downlink synchronization speed, and improves the terminal access performance. In this paper, the improved algorithm is simulated by using the LTE system level simulation platform. The simulation results show that the synchronization performance of the improved algorithm is similar to that of the traditional algorithm in the case of low SNR. However, the algorithm improves the speed of SSS's maximal m-correlation value based on odd and even sequences, and the synchronization accuracy is better than the traditional algorithm, and the memory consumption is greatly reduced. When the SNR is large enough, the accuracy rate of the algorithm is the same. Therefore, the improved algorithm proposed in this paper can meet the requirements.
【學位授予單位】：武漢郵電科學研究院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN929.5

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