一种正交频分复用定时同步算法及其硬件实现优化

A new algorithm for OFDM timing synchronization and hardware implementation optimization

针对在多径信道环境中由于多径反射导致正交频分复用(OFDM)符号的循环前缀会受到符号间干扰(ISI)的问题,本文提出一种时域定时同步算法:相关峰斜率检测算法。该算法通过对相关峰斜率的检测确定最后一径位置,估计出多径信道弥散长度,从而使后继傅立叶变换(FFT)开窗位置避开ISI。与经典算法对比,本算法可更好地避免ISI,特别是在CT-8信道中全部避开ISI。另外,针对类似NB-IOT采用了OFDM技术的低成本物联网通信系统,对算法进行了简化,可降低物联网终端基带芯片实现的代价,减少终端成本。

This article introduces an algorithm for orthogonal frequency divisition multiplexing(OFDM)timing synchronization—correlated peak slope detection algorithm. In a multipath channel environment,due to multipath reflection,the front part of the cyclic prefix that OFDM complies with will be affected by Inter Symbol Interference(ISI). This paper innovatively proposes a time-domain timing synchronization algorithm. The algorithm determines the arrival position of the last path by detecting the slope of the correlation peak,and estimates the dispersion length of the multipath channel,so that the subsequent fast Fourier transform(FFT)window position avoids the ISI,and provides a reference value for the selection of filter coefficients for channel estimation. This algorithm is also very suitable for application in multipath channels with equal strength and two paths. Finally,the algorithm was simulated with MATLAB and compared with the classic algorithm,which proved that the algorithm can better avoid ISI in the case of low signal-to-noise ratio. In addition,for a low-cost IoT communication system similar to NB-IOT that uses OFDM technology,this article simplifies the algorithm,which can reduce the cost of implementing the baseband chip of the IoT terminal and reduce the cost of the terminal.