基于小波脊线的OFDM与单载波信号识别

Recognition of OFDM and Single Carrier Digital Signals Based on Wavelet Ridge

正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)与单载波信号广泛应用于短波通信领域。针对低信噪比和多径环境下OFDM与单载波信号识别效率低的问题,本文提出了基于小波脊线的信号识别算法。本文推导了常用信号对应的小波脊线幅度和脊点位置,并分析了小波脊线幅度和脊点形态。通过理论推导和仿真测试证明了OFDM与单载波信号对应小波脊线具有不同特征,对小波脊线差分、中值滤波、并利用其熵作为特征值能够有效的进行OFDM信号与单载波信号的识别。仿真结果证明该算法对输入信号点数要求低,在低信噪比和短波中等信道下识别效果具有稳健性和有效性。

Orthogonal Frequency Division Multiplexing（OFDM）and single carrier digital signals are widely used in High Frequency （HF）communication.Aim at OFDM signals and single carrier digital signals have a low recognition efficiency in lower signalto -noise ratio（SNR）and multi-path environment in HF communication,a new algorithm based on wavelet ridge is proposed.According to the wavelet ridge amplitude and wavelet ridge patterns characters can reflect instantaneous different characters of different signals types,derivation is provided of the normal used signals＇ wavelet ridges characters in mathematical formula also.Corresponding to the difference between OFDM signals and single carrier digital signals in wavelet ridge amplitude and wavelet ridge patterns,differential coefficient, median filter are used in this paper,and then calculate entropy of the wavelet ridges after differential coefficient and median filter as a feature value,finally achieved to recognize of OFDM signals and single carrier digital signals.Computer simulation shows that the algorithm is not sensitive to the input signal points and this algorithm is both feasible and effective in low SNR environment.