DRSN与集成融合的OFDM辐射源个体识别方法
DRSN and Integrated Fusion OFDM Radiation Source Individual Identification Method
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摘要: 针对在低信噪下通信辐射源识别率低的问题,提出一种DRSN(Deep Residual Shrinkage Networks)与集成融合的OFDM辐射源个体识别方法。首先,从OFDM发射机产生信号的原理出发,对可能产生OFDM发射机指纹差异的来源进行分析,对相邻帧OFDM信号做相干积累,有效提升OFDM信号的信噪比,通过截取OFDM前导信号,减少因传输内容差异所带来的影响,对OFDM前导信号进行功率累加和双谱对角切片信号处理,构建OFDM前导信号的多域数据集;随后,将OFDM前导信号多域数据分别送入具有自动软阈值化去噪和具有跨层连接结构防止梯度消失的DRSN网络进行训练,有效减少噪声对发射机指纹信号的干扰和避免阈值设置不佳所带来识别效果不佳的问题,并且在DRSN网络训练时采用5折交叉验证的策略,防止网络训练中出现过拟合的现象,利用Stacking集成学习思想实现3个DRSN网络初级预测结果的融合;最后,将融合结果作为次级数据送入逻辑回归LR(Logistic Regression)次级线性分类器,利用ECOC(Error Correcting Output Code)策略将多分类任务转为二分类任务,对样本类别进行编码,当测试样本经过二分类器获得一组预测类别编码后,通过计算样本类别编码与预测类别编码之间的欧式距离,根据最小欧式距离所属类别来确定最终分类结果。在公开数据集上的实验结果表明:对比其他深度学习的方法,信噪比为5 dB和0 dB时,DRSN与集成融合的OFDM辐射源识别的准确率分别为97%和95.88%,并且具有较低的复杂度,能够验证在低信噪比下该方法的有效性。Abstract: A method for identifying individual OFDM radiation sources based on a deep residual shrinkage network (DRSN) and integrated shrinkage network was investigated with the goal of improving the low identification rate for communication radiation sources under low signal noise. First, starting from the principle of OFDM-transmitter signal generation, the sources that can produce fingerprint differences in OFDM transmitters were analyzed, and the coherent accumulation of OFDM signals in adjacent frames was performed to effectively improve the signal-to-noise ratio of the OFDM signals. The impact of differences in the transmission content was reduced by intercepting the leading OFDM signals. The power accumulation and bispectral diagonal slicing signal processing of the leading OFDM signals were performed to construct a multi-domain data set of the leading OFDM signals. Then, this multi-domain data were sent to a DRSN network with an automatic soft threshold denoising and cross-layer connection structure to prevent gradient disappearance for training, which effectively reduced the interference of noise on the transmitter fingerprint signal and prevented the problem of a poor recognition effect caused by a poor threshold setting. In addition, a 5-fold cross-validation strategy was adopted to train the DRSN network. Overfitting was prevented during the network training, and the integrated learning concept was used to integrate the primary prediction results of the three DRSN networks. Finally, the fusion results were sent to a logistic regression sub-linear classifier as secondary data, the ECOC strategy was used to convert the multi-classification task into a binary classification task, and the sample category was encoded. After the test sample passed through the binary classifier, a set of predictive category codes was obtained. By calculating the Euclidean distance between the sample category code and predicted category code, the final classification result was determined based on the minimum Euclidean distance. Experimental results on public data sets showed that compared with other deep learning methods, when the SNR was 5 dB and 0 dB, the accuracies of the DRSN and integrated fusion OFDM radiation source identification were 97% and 95.88%, respectively, with low complexity, which verified the effectiveness of this method at a low signal-to-noise ratio.