MIMO processing enables jammer mitigation through spatial filtering, provided that the receiver knows the spatial signature of the jammer interference. Estimating this signature is easy for barrage jammers that transmit continuously and with static signature, but difficult for more sophisticated jammers: Smart jammers may deliberately suspend transmission when the receiver tries to estimate their spatial signature, they may use time-varying beamforming to continuously change their spatial signature, or they may stay mostly silent and jam only specific instants (e.g., transmission of control signals). To deal with such smart jammers, we propose MASH, the first method that indiscriminately mitigates all types of jammers: Assume that the transmitter and receiver share a common secret. Based on this secret, the transmitter embeds (with a linear time-domain transform) its signal in a secret subspace of a higher-dimensional space. The receiver applies a reciprocal linear transform to the receive signal, which (i) raises the legitimate transmit signal from its secret subspace and (ii) provably transforms any jammer into a barrage jammer, which makes estimation and mitigation via MIMO processing straightforward. We show the efficacy of MASH for data transmission in the massive multi-user MIMO uplink.

翻译：MIMO处理技术可通过空间滤波实现干扰抑制，前提是接收端已知干扰信号的空间特征。对于连续发射且空间特征不变的压制式干扰，该特征易于估计，但应对更复杂的干扰类型时则困难重重：智能干扰机可能在接收端试图估计其空间特征时故意中断发射，通过时变波束成形持续改变空间特征，或长期保持静默仅在特定时刻（如控制信号传输时）发动干扰。针对此类智能干扰，我们提出MASH——首个能无差别抑制所有类型干扰的方法：假设收发双方共享一个公共秘密，发射端基于该秘密通过线性时域变换将信号嵌入高维空间的秘密子空间中。接收端对接收信号施加互逆线性变换，该变换能（i）从秘密子空间中提取出合法发射信号，且（ii）可证地将任意类型干扰转化为压制式干扰，从而通过标准MIMO处理实现轻松估计与抑制。我们在大规模多用户MIMO上行数据传输中验证了MASH的有效性。