Abstract: An improved frame synchronization scheme based on CAZAC（Constant Amplitude Zero Auto Correlation） sequences is presented.Firstly，the CAZAC sequence is used as a short training sequence to change the standard preamble structure of IEEE 802.11a，and the number of the short training sequence for coarse frequency estimation is increased.Secondly，the proposed algorithm employs the cross-correlation of the short training sequence with a threshold to implement the frame synchronization.Because of the good correlation properties of CAZAC sequences and the synchronization information of its cross-correlation，higher accurate frame synchronization can be achieved，and the coarse frequency estimation is considerably improved.Furthermore，the stable performance of frame synchronization detection is also acquired even at the large frequency offset.Simulation results show that the proposed algorithm can get 2 dB gain compared with that of traditional algorithm when multi-path delay is 100 ns and frequency offset is 200 kHz.

摘要： 提出了一种基于CAZAC（Constant Amplitude Zero Auto Correlation）的改进帧同步检测方案。首先，利用CAZAC序列作为短训练序列来改变IEEE 802.11a系统标准前导结构，并增加用于粗频偏估计的短训练序列个数；其次，在使用延时相关帧检测的基础上，结合短训练序列的互相关信息共同完成帧同步检测。由于CAZAC序列良好的自身特性以及互相关信息的辅助，使得帧同步检测更加准确，粗频偏估计的性能也有所提高，大频偏下仍得到稳定的性能。仿真结果显示，在多径时延为100 ns，频偏为200 kHz时，与传统方法比较能得到约2 dB的增益。