多径信道下的OFDM系统定时同步

对于无线通信系统而言,正交频分复用(OFDM:Orthogonal Frequency Division Multiplexing)是一种非常有吸引力的传输技术,但是由于多径产生的ISI(Inter-SymbolInterference)和信道噪声破坏了OFDM信号保护间隔,影响了定时准确性和精度.为此利用循环扩展前缀与相应的复制数据之间的相关性,提出了两种采用多个符号归一化的点相关和的定时同步算法,给出了其实现步骤及相关参数的选择原则.最后给出一种定时同步的实现方案,将其应用在DVB-T(Terrestrial Digital Video Broadcasting)中,利用计算机仿真对该系统的定时进行了分析.仿真结果表明,新方案与传统的ML(Maximum Likelihood)相比,可以准确稳定地获得定时同步.

OFDM Timing Ssynchronization under Multi-Path Channels

OFDM (Orthogonal Frequency Division Multiplexing) is an attractive technique for wireless communication applications. However, ISI (Inter-Symbol Interference) resulted from multi-path and noise contaminate the guard interval of the OFDM symbols,that influences the correction and precision of timing synchronization. Two timing algorithms are proposed according to the correlation between the guard intervals and their corresponding duplicates at the symbol tail.The principle to select concerned parameters is also given. A new symbol timing synchronization scheme is developed and applied to the DVB-T system. It is shown from the results that the new scheme is more precise and stable compared with the traditional ML (Maximum Likelihood) algorithm.