不同标准类型的OFDM信号识别方法

Identification method for OFDM signals of different standards

目前正交频分复用(OFDM)信号识别研究已有众多方法,但不同标准类型的OFDM信号识别的研究尚不多见。针对这类问题,提出了一种不同标准类型的OFDM信号识别方法。该方法首先提出基于逼近采样信号频谱截止频率的过采样率估计方法,依据估计出的过采样率,采用改进的时域可变延迟自相关方法估计出OFDM信号的子载波个数,然后基于高阶累积量的二阶和四阶的组合特征量估计出空载波个数,最后将估计出来的子载波个数和空载波个数与标准协议相比较,从而识别出不同标准协议的OFDM信号。仿真实验结果表明,该方法在低信噪比多径信道下有效地实现了不同标准类型的OFDM信号识别。

At present,there exist a lot of methods with Orthogonal Frequency Division Multiplexing（OFDM） signals identification,among which there are few methods focusing on OFDM signals identification for different standards.To solve the problem,a novel method to solve the identification problem for OFDM signals of different standards is proposed in this paper.Firstly,a cosine roll-off filter is designed to estimate the oversampling factor whose cut-off frequency is con-sidered as the approximation of that of the sampling signal＇s spectrum.And then,the number of OFDM subcarrier is esti-mated by means of time-domain variable time-delay autocorrelation.In addition,the method uses the combination charac-teristic of fourth-order and second order cumulant to estimate the number of OFDM null carrier.Finally,the estimated number of OFDM subcarrier and null carrier are compared to that in different standard protocols of OFDM to identifica-tion of OFDM signals.The simulation results show that the method improves effectively the performance with different standards of OFDM signals recognition in low SNR and multipath channels conditions.