Research on Co-channel Base Station Interference Suppression Method of Passive Radar Based on LTE Signal
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摘要: 针对基于LTE信号的外辐射源雷达接收信号包含多个同频发射基站的直达波和多径杂波干扰的问题,该文对传统的外辐射源雷达信号处理流程进行了改进,增加了对同频基站干扰的处理步骤,提出了一种基于卷积混合模型的盲源分离算法来抑制同频基站的杂波干扰。假设混合矩阵是一个矢量线性时不变滤波器矩阵,以互信息为代价函数,通过求取互信息的梯度,用最速下降法进行迭代,分离准则是使分离后的信号之间互信息最小化。仿真表明,该文算法能够有效地抑制LTE信号同频发射基站的杂波干扰,为后续的主基站杂波对消处理提供了基础。Abstract: For the passive radar based on LTE signal, the received signal contains direct-path and multipath clutters interference of multiple co-channel base station, and the traditional passive radar signal processing flow is improved, and the processing steps of co-channel base station interference are added. A blind source separation algorithm based on convolutive mixtures is proposed. The algorithm can suppress the clutters interference of co-channel base station. It is assumed that the mixing matrix is a vector linear time-invariant filter matrix. The mutual information is used as a cost function. By finding the gradient of mutual information, it is iterated by the steepest descent method. The separation criterion is to minimize the mutual information between the separated signals. The simulation results show that the proposed algorithm can effectively suppress the clutters interference of the LTE signal co-channel base station, and provide a basis for the subsequent clutters cancellation processing of the main base station.
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表 2 仿真参数
主基站 同频干扰基站 强干扰 弱干扰 目标 强干扰 弱干扰 直达波 多径1 多径2 多径3 多径4 目标1 目标2 直达波 多径1 多径2 时延(μs) 0 0.23 0.26 0.29 0.03~3.22 15.92 22.75 12.99 35.22 13.02~16.24 衰减(dB) 0 –12 –20 –21 –46 –34 –23 –6 –7.5 –46 表 1 基于卷积混合模型的盲源分离算法
初始化:Y(n)=X(n); 循环迭代: (1)从{–M,–M+1,···,+M}中选择一个随机值m; (2)计算(Y1(n),Y2(n-m))之间的互信息梯度${{\text{β}}_{{{\text{Y}}^{\left( m \right)}}}}$; (3)更新输出:Y(m)←Y(m)-${\rm{\mu }}{{\text{β}}_{{{\text{Y}}^{\left( m \right)}}}}$(Y(m)); 归一化:移除DC分量,并令Yi=Yi/${{\rm{\sigma }}_{\rm{i}}}$,${{\rm{\sigma }}_{\rm{i}}}$为Yi的标准偏差; (4)由式(8)计算分离矩阵Bk, k=0,1,···,p; (5)令Y(n)=[B(z)Y(n)]; 收敛或达到最大迭代次数后停止循环。 -
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