TD-LTE下行时频同步算法研究与实现

发布时间：2018-06-29 22:35

本文选题：TD-LTE + 主同步信号　；参考：《电子科技大学》2014年硕士论文

【摘要】：近30多年来无线移动通信技术飞速发展,各种新技术层出不穷,而正交频分复用(OFDM)技术凭借其独特的优势脱颖而出,成为了当代通信系统的主流技术。OFDM系统的一个最大的缺点就是系统对同步误差非常敏感,因此同步技术的研究变得非常重要。本文围绕以OFDM技术为核心的TD-LTE系统下行时频同步技术而展开,完成了下行主同步信号(PSS)同步的具体FPGA链路设计与实现。同时,本文在传统基于互相关的PSS检测算法上提出了一种改进的PSS相关检测算法及其实现结构,该改进算法能大幅降低实现复杂度,减少了所需的硬件资源。首先,本文简要介绍了TD-LTE的物理层相关结构,着重介绍了下行同步信号,特别针对下行同步小区搜索算法进行了研究,并对其中主同步信号检测同步算法和粗频偏估计算法进行了重点分析与性能仿真。其次,本文以基于互相关的PSS检测定时算法和基于PSS的频偏估计算法为核心,根据3GPP规范,进行了TD-LTE下行主同步信号同步的FPGA链路具体设计与实现,完成了5ms系统半帧定时,小区组内ID识别,小数倍载波频偏估计,辅同步信号(SSS)提取等功能。并对其中ADC基带接口,FIR低通滤波,截位与下采样,匹配相关计算,定时脉冲生成,载波频偏估计,辅同步信号提取等几个关键模块进行了详细的仿真与测试,测试结果表明设计链路达到了预期功能。最后,本文在传统基于互相关的PSS检测算法上提出了一种改进型低复杂度PSS相关检测算法及其实现结构,该算法是传统PSS互相关算法的数学近似,仅用一组实数匹配滤波处理就能完成复杂的PSS相关计算。由于引进了噪声项,改进算法在性能上相比传统算法有所下降,但是能非常有效的降低实现复杂度和所需的硬件资源,在信噪比较高,信道环境较好的场景下有着不错的适用性。
[Abstract]:In recent 30 years, with the rapid development of wireless mobile communication technology, a variety of new technologies emerge in endlessly. Orthogonal Frequency Division Multiplexing (OFDM) technology stands out because of its unique advantages. One of the biggest disadvantages of OFDM system, which has become the mainstream technology of modern communication system, is that the system is very sensitive to synchronization error, so the research of synchronization technology becomes very important. This paper focuses on the downlink time-frequency synchronization technology of TD-LTE system with OFDM technology as the core, and completes the FPGA link design and implementation of downlink main synchronous signal (PSS) synchronization. At the same time, this paper proposes an improved PSS correlation detection algorithm and its implementation structure based on the traditional cross-correlation-based PSS detection algorithm. The improved algorithm can greatly reduce the complexity of the implementation and reduce the required hardware resources. Firstly, the physical layer correlation structure of TD-LTE is briefly introduced, and the downlink synchronization signal is introduced, especially for the downlink synchronous cell search algorithm. The main synchronous signal detection synchronization algorithm and coarse frequency offset estimation algorithm are analyzed and simulated. Secondly, based on cross-correlation detection timing algorithm and frequency offset estimation algorithm, according to 3GPP specification, the design and implementation of 5ms downlink main synchronous signal synchronization link is carried out, and the half-frame timing of 5ms system is completed. In-cell ID identification, fractional double carrier frequency offset estimation, auxiliary synchronous signal (SSS) extraction and other functions. Several key modules, such as Fir low-pass filter, intercept and down-sampling, matching correlation calculation, timing pulse generation, carrier frequency offset estimation, auxiliary synchronous signal extraction and so on, are simulated and tested in detail, including ADC baseband interface Fir low-pass filtering, intercept and down-sampling, matching correlation calculation, timing pulse generation, carrier frequency offset estimation, auxiliary synchronous signal extraction and so on. The test results show that the designed link achieves the expected function. Finally, an improved low complexity PSS correlation detection algorithm and its implementation structure are proposed in this paper, which is a mathematical approximation of the traditional PSS cross-correlation algorithm. The complex PSS correlation calculation can be accomplished by only a set of real matched filter processing. Because of the introduction of noise terms, the performance of the improved algorithm is lower than that of the traditional algorithm, but it can reduce the complexity of implementation and the required hardware resources very effectively, and has a higher signal-to-noise ratio (SNR). The channel environment under the better scenario has a good applicability.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

【共引文献】