中文摘要：

针对宽带短波通信正交频分复用（OFDM）系统，提出了一种不需要数据辅助的高效符号定时同步方法。该方法利用OFDM符号中的空载波不传输任何数据这一特性，通过最小化空载波上的数据能量来将符号定时点锁定在安全区域内，从而完成符号定时同步。该方法可以有效对抗多径效应，适用于短波通信系统。最后将该方法与Al-Dweik同步方案在宽带短波信道条件下进行了仿真对比．结果表明该方法有著曼精确的符号定时同步性能．并且适用干各种星座图调制．

英文摘要：

An efficient non-data-aided（NDA） symbol timing synchronization approach is proposed for or-thogonal frequency division multiplexing（OFDM） systems in wideband shortwave or high frequency （HF） communication. Based on the property that null subcarriers carry no data, this method can lock the timing point into the safe region through minimizing the power of signals in null subcarriers, thus achieving symbol timing synchronization. It can effectively combat the multipath effects which is desirable for HF communi-cation. Simulation results confirm that compared with the Al-Dweik＇ s scheme, the proposed approach yields a better synchronization performance and is applicable to various signalling constellations over wide- band HF communication channels.