电力线OFDM系统整数频偏估计算法

Integer Frequency Offset Estimation Algorithm of Orthogonal Frequency Division Multiplexing System in Power Line Communication Channels

正交频分复用(orthogonal frequency division multiplexing,OFDM)技术是电力线通信中重要的调制技术,而OFDM系统的主要缺点之一是对载波频率偏移非常敏感,故载波频偏估计是OFDM系统的关键技术之一。对采用Chu序列的互相关整数频偏估计算法进行改进,提出了基于最大后验概率准则的整数频偏估计算法。该算法在原有算法基础上考虑训练序列周围的数据符号和噪声影响,增加了一个修正项,可以进一步降低整数频偏估计错误检测概率,提高估计的准确性。仿真结果表明,与原互相关算法相比,该算法降低了一般通信信道和电力线通信信道下的整数频偏估计错误检测概率,在电力线OFDM通信系统中具有良好的应用前景。

Orthogonal frequency division multiplexing（OFDM） technology is an important modulation technology of the power line communication（PLC）, but one of the main shortcomings of an OFDM system is its high sensitivity to the carrier frequency offset（CFO）. Therefore, CFO estimation is one of the key technologies of an OFDM system. A maximuma-posteriori（MAP） criterion algorithm for integer frequency offset（IFO） estimation was proposed in this paper, and the cross-correlation based IFO estimation algorithm with Chu sequence was improved. The proposed algorithm took the data symbols around training sequence and the noise into consideration on the basis of the original algorithm, and a correction term was added in the algorithm. The algorithm can further reduce the error detection probability of the IFO estimation and improve the estimation accuracy. The simulation results show that, compared with the original cross-correlation algorithm, the proposed algorithm has a lower error detection probability of the IFO estimation in the general communication channels and the power line communication channels, thus possesses a good application prospect in the OFDM system of power line communication channels.