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处理可通过空间滤波实现干扰抑制，前提是接收端掌握干扰信号的空间特征。对于连续发射且特征恒定的全频段干扰机，该特征估计较为简便；但面对更复杂的干扰机时却困难重重：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传输，可能使用时变波束成形不断改变空间特征，或长期保持静默仅针对特定时刻（如控制信号传输）发动攻击。为应对此类智能干扰机，本文提出MASH——首个能无差别抑制所有类型干扰机的方法。假设收发双方共享同一秘密，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隐秘子空间。接收端对接收信号施加互逆线性变换，该变换能够：(i) 将合法传输信号从其隐秘子空间中提取出来，(ii) 可证明地将任意干扰机转化为全频段干扰机，从而使得通过MIMO处理进行估计与抑制变得简单直接。我们在大规模多用户MIMO上行数据传输场景中验证了MASH的有效性。