基于LTE的下行同步算法研究与仿真

发布时间：2018-06-03 09:48

本文选题：下行同步 + 正交频分复用　；参考：《武汉邮电科学研究院》2017年硕士论文

【摘要】：LTE下行同步技术是每一个移动设备接入无线网络的第一步,无线终端必须通过小区搜索来接收到广播信道中的目标小区标识,获得时间和频率同步。[1]对下行同步过程的研究对于整个系统来说十分关键,可以通过对接入算法的研究来提升终端的接入速度,提高内存的利用效率。因此,对下行同步算法的研究具有重要的应用价值。本文重点研究了LTE的同步过程和传统的算法,分析得出了几个重要的特点,如由不同的根序列生成的主同步信号中,存在着实部相同,虚部互为相反数的特点。在m序列中,总结出m"序列始终小于m#序列,以及小区组表示和他们之间的算数关系等。结合以上发现的重要特点,本文对算法进行了改进优化,实现过程中使用了改进的基于互相关算法实现主同步信号同步,然后根据主同步信号进行定时同步和ML算法实现频偏估计,基于循环前缀长度假设算法确定所使用的循环前缀类型,以及使用基于奇偶序列的最大m相关值实现辅同步信号同步算法。解决了下行同步过程中避免进行不必要的重复的大型即时运算,并优化了消耗的本地存储资源,加快下行同步速度,提高终端接入性能。本文使用LTE系统级仿真平台,对改进的算法进行了仿真,仿真实验的结果表示,在信噪比较低的情况下,PSS的同步性能与传统算法相比,性能相差无几,但算法运算速度有所提高。SSS的基于奇偶序列的最大m相关值在信噪比不高的情况下,同步正确率优于传统算法,且占用内存大量减少;当信噪比足够大时,算法正确率一致。因此,本文提出的改进后的算法能够满足需求。
[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.
【学位授予单位】：武汉邮电科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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