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针对低压电力线信道噪声干扰强、多径衰落严重,而传统同步算法保密性弱、小数倍载波频偏估计易受多径衰落影响的缺点,提出一种适合于低压电力线通信信道的正交频分复用(orthogonal frequency division multiplexing,OFDM)时频同步算法。将超混沌系统生成的混沌序列用于构造同步训练序列,提出新的定时偏差估计和小数倍频偏估计的算法,在延续循环移位的思想的基础上完成整数倍频偏估计。理论分析表明,混沌系统对初始值的敏感性与所提出的算法相结合,可极大地增强系统的保密性。仿真结果表明,所提出的定时偏差估计准确率高、频偏估计性能更优,能有效地对抗低压电力线通信信道的强噪声和多径衰落。
Aiming at the shortcomings of strong interference of low-voltage power line channel noise, severe multi-path fading, weak confidentiality of traditional synchronization algorithm and small fractional carrier frequency offset estimation, the proposed method is suitable for low frequency power line communication channel of orthogonal frequency The orthogonal frequency division multiplexing (OFDM) time-frequency synchronization algorithm. The chaos sequence generated by hyperchaos system is used to construct synchronous training sequence, and a new algorithm of timing offset estimation and fractional frequency offset estimation is proposed. Based on the idea of continuation of cyclic shift, integer frequency offset estimation is completed. Theoretical analysis shows that the sensitivity of the chaotic system to the initial value combined with the proposed algorithm can greatly enhance the system’s confidentiality. The simulation results show that the proposed timing offset has high accuracy and better performance of frequency offset estimation, which can effectively combat strong noise and multipath fading of low-voltage power line communication channel.