In this paper, a novel demodulation structure in high-frequency (HF) channel is introduced and studied.Frequency-offset estimation, ractionally spaced adaptive equalization and carrier recovery techniques are involved.Frequency-offset correction is

频率同步是宽带OFDM系统中的关键技术，IEEE 802.11a 采用OFDM技术，利用其前导序列的重复结构，提出了一种分步的粗细频偏捕获与校正算法，同时为了补偿时域同步后的残余相差和适应信道的时变特性，还提出了一种基于频域导频的相位跟踪方案-Frequency synchronization is a key technology in the broadband OFDM systems, IEEE 802.11a uses OFDM technology, the use of the r

OFDM is a multi-carrier transmission technique. It converts the frequency selective fading channel into a collection of parallel flat fading sub-channels which simplifies the structure of a receiver. OFDM has been widely used in communication system