短波低信噪比OFDM猝发通信系统同步算法

为解决低信噪比下短波正交频分复用（OFDM）系统信号的捕获,提出了一种采用CAZAC序列设计导频符号的基于谱分析的同步算法。首先通过时域、频域2维联合估计来实现信号的快速捕获,同时根据信号谱函数的最大峰值位置来确定整数频偏,然后利用相邻导频符号的相位差来精确估计小数频偏。最后,进行了算法仿真和现场可编程门阵列（FPGA）上的硬件实现及在线实时验证研究,结果表明,该同步方案在低信噪比条件下具有很好的同步性能,可以作为一个完整OFDM基带处理器的子模块实时、连续地对信号进行处理。

Synchronization Algorithm for OFDM Burst Communication Systemat HF Low SNR Environments

A synchronization algorithm modulated multiple pilot symbols using Constant Amplitude Zero Auto-Correlation (CAZAC) sequence and based on spectral analysis was presented for HF OFDM signal acquisition under low signal to noise ration. The fast signal acquisition was realized by time-frequency domain two-dimension estimation, and synchronously the integer frequency shift can be obtained by the maximal peak position of spectrum function. Then the phase difference of adjacent pilot symbols was used for precisely fractional frequency shift estimation. Finally, matlab simulations and on-chip real-time analysis of the algorithm using FPGA were done. The results demonstrate that this algorithm achieves fine performance at low SNR and can work efficiently as a block of an OFDM baseband receiver processor.