MIMO-OFDM系统同步技术研究

【作者】 王霞；

【导师】 谢仁宏；

【作者基本信息】 南京理工大学 ， 通信与信息系统， 2013， 硕士

【摘要】 正交频分复用(OFDM)技术采用多载波调制方式,能够有效对抗多径干扰且频谱利用率高。多输入多输出(MIMO)技术能够增加系统容量,提高数据速率,是目前无线通信的一项重要技术。结合OFDM和MIMO两种技术构成的MIMO-OFDM系统,是目前移动通信的核心技术之一。然而MIMO-OFDM系统对同步误差非常敏感,因此精确的同步对MIMO-OFDM系统尤为重要。本文从MIMO-OFDM原理出发,将同步误差对MIMO-OFDM系统产生的影响以及目前同步研究现状进行了详细分析。在此基础上对SISO-OFDM经典同步算法进行了分析,针对传统同步算法精度较低的问题,提出了一种基于Chu序列的改进算法,解决了以往同步算法精度不高的问题。在研究MIMO-OFDM同步算法时也将Chu序列用于MIMO-OFDM系统同步并与经典的MIMO-OFDM系统同步算法比较,仿真表明基于Chu序列的同步算法具有更高的定时同步检测概率和较低的计算量。本文重点对突发分组模式的MIMO-OFDM系统同步进行分析,通过构造特殊结构的前导序列并采用全时域同步方案,可快速实现时间同步和频率同步。时间同步针对以往同步算法的不足提出了改进算法,仿真得出改进算法在AWGN信道和Rayleigh信道下都有更高的检测概率。频率同步利用前导序列的特殊结构提出了改进算法,仿真得出改进算法具有更小的频偏估计均方误差,且利用分集接收可以提高频偏估计精度。更多还原

【Abstract】 Orthogonal Frequency Division Multiplexing (OFDM) which is based on multi-carrier modulation can be effective against multi-path interference and have high spectrum efficiency. Multi-Input Multi-Output (MIMO) is a key technology for wireless communication which can significantly increase system capacity and data rates. As the combination of the two technology, MIMO-OFDM system has a high channel capacity and spectral efficiency,and now is becoming one of the core technology of the new generation mobile communication. But on one side, MIMO-OFDM system is sensitive to synchronization error, so the precise synchronization is very important for MIMO-OFDM system.This paper is based on MIMO-OFDM system, and will do a detailed analysis of how the synchronization errors will affect the performance of MIMO-OFDM system as well as do a synchronization research. Based on this analysis, then the synchronization algorithms of SISO-OFDM are discussed in detail. For the deficiencies in the synchronization algorithm on the basis of the analysis of the classic synchronization algorithms, a new algorithms based on sequence-Chu sequence is given. Also, the Chu sequence is used in MIMO-OFDM systems synchronization. The simulation shows that the synchronization algorithm based on Chu sequence having a higher timing synchronization detection probability and low the amount of calculation.Synchronized analysis of the MIMO-OFDM systems of this paper focuses on the burst packet mode, full-time domain synchronization scheme and special preamble structure are used in this paper because of it’s quickly estimation. The improved time synchronization algorithms are given based on the traditional synchronization algorithm, and the simulation results show that the improved algorithm has a higher probability of detection in AWGN and Rayleigh channel. Also, the improved frequency synchronization algorithms using the special structure of the preamble sequence have a smaller offset estimation mean-square error, and the frequency offset estimation accuracy can be improved using diversity reception.更多还原