OFDM系统的最大似然同步算法研究

The Study on Maximum Likelihood Estimation Algorithm in OFDM System

虽然OFDM技术有很多优势,但相对于单载波系统或者一般的频率复用通信系统来说,它对同步要求更高。假设终端与基站无法实现同步,终端甚至无法接入,同步技术是OFDM系统以及MIMO-OFDM系统的关键技术,是保证系统高稳定和高性能重要技术。最大似然估计算法在OFDM符号定时同步和载波频率同步中得到了广泛的应用,通过基于循环前缀的最大似然估计方法,避免了基于导频符号同步估计带来功率和数据资源浪费。通过仿真可以看到,该算法能够很好地实现OFDM系统的符号同步和载波同步。

Although OFDM has many advantages compared with single -carrier systems or other FDM （Frequency Division Multiplexing） systems, one of disadvantages in OFDM is sensitive to frequency offset in the channel. So the problem of synchronization is essential to OFDM systems. If the terminal and base station do not synchronize, the terminal can not access to systems. Synchronization technology is the key one in OFDM and MI- MO -OFDM and the guarantee for the quality and stability. The maximum likelihood estimation algorithm has been widely used in symbol timing synchronization and carrier frequency synchronization of OFDM, thus to avoid the waste of frequency resources and power and data resulted from pilot symbol -based synchronization estima- tion. The simulation results indicate that the method could achieve symbol synchronization and carrier synchroni- zation of OFDM systems.