Wireless systems must be resilient to jamming attacks. Existing mitigation methods based on multi-antenna processing require knowledge of the jammer's transmit characteristics that may be difficult to acquire, especially for smart jammers that evade mitigation by transmitting only at specific instants. We propose a novel method to mitigate smart jamming attacks on the massive multi-user multiple-input multiple-output (MU-MIMO) uplink which does not require the jammer to be active at any specific instant. By formulating an optimization problem that unifies jammer estimation and mitigation, channel estimation, and data detection, we exploit that a jammer cannot change its subspace within a coherence interval. Theoretical results for our problem formulation show that its solution is guaranteed to recover the users' data symbols under certain conditions. We develop two efficient iterative algorithms for approximately solving the proposed problem formulation: MAED, a parameter-free algorithm which uses forward-backward splitting with a box symbol prior, and SO-MAED, which replaces the prior of MAED with soft-output symbol estimates that exploit the discrete transmit constellation and which uses deep unfolding to optimize algorithm parameters. We use simulations to demonstrate that the proposed algorithms effectively mitigate a wide range of smart jammers without a priori knowledge about the attack type.

翻译：无线系统必须能够抵御干扰攻击。现有的基于多天线处理的缓解方法需要获取干扰机的发射特性，这在面对仅在特定时刻发射以规避缓解的智能干扰机时可能难以实现。我们提出了一种新方法，用于缓解大规模多用户多输入多输出（MU-MIMO）上行链路中的智能干扰攻击，该方法无需干扰机在任意特定时刻保持活跃。通过构建一个统一干扰估计与缓解、信道估计以及数据检测的优化问题，我们利用干扰机在相干间隔内无法改变其子空间这一特性。针对所提问题的理论分析表明，其解在特定条件下能够保证恢复用户数据符号。我们开发了两种高效迭代算法来近似求解该问题：MAED（一种无参数算法，采用带箱型符号先验的前后向分裂法）和SO-MAED（将MAED的先验替换为利用离散发射星座的软输出符号估计，并通过深度展开优化算法参数）。仿真结果表明，所提算法能在无需预知攻击类型的情况下有效缓解多种智能干扰攻击。