Universal MIMO Jammer Mitigation

TL;DR

Universal MASH introduces a secret-subspace embedding that transforms any jammer into a barrage jammer, enabling effective MIMO mitigation in massive MU-MIMO uplinks. By raising the received signal with a secret unitary transform, transmit signals remain recoverable while jammer interference is confined to a barrage-like structure, allowing simple projection-based or LMMSE/JMD detectors. The paper provides theoretical guarantees (including a residual bound for barrage mitigation), a reciprocal MASH variant for per-UE secrets, and practical, efficient embedding/raising transforms, alongside extensive simulations across diverse jammer types. The results demonstrate robust, universal jammer mitigation with configurable complexity and secret-distribution strategies, offering a practical path toward jammer-resilient next-generation networks.

Abstract

Multi-antenna 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, or they may use time-varying beamforming to continuously change their spatial signature. 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 time-domain transform) its signal in a secret subspace of a higher-dimensional space. The receiver applies a reciprocal 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, making estimation and mitigation via multi-antenna processing straightforward. Focusing on the massive multi-user MIMO uplink, we present three MASH-based data detectors and show their jammer-resilience via extensive simulations. We also introduce strategies for multi-user communication without a global secret as well as methods that use computationally efficient embedding and raising transforms.

Figures (8)

• Figure 1: Error-rate performance of a coherent communication receiver that uses a training-period-based orthogonal projection for mitigating the jammer, least squares channel estimation, and LMMSE data detection. The setup is described in sec:eval and the $10$-antenna jammers are a barrage jammer transmitting i.i.d. $\mathcal{C}\xspace\mathcal{N}\xspace(0,1)$ symbols as well as the jammers $\Circled[inner color=white, fill color= gray, outer color=gray]{\scriptsize{\textnormal{6}}}$ and $\Circled[inner color=white, fill color= gray, outer color=gray]{\scriptsize{\textnormal{7}}}$ from sec:jammers.
• Figure 2: Probability bound $1-\bar{P}(\alpha)$ that the residual interference power bound in \ref{['eq:intf_bound']} does not hold, as a function of the threshold $\alpha$, and for different redundancies $R$. As in sec:eval, the frame length is $L=100$. Note that the curves' asymptotic slope of descent (in doubly-logarithmic scale) coincides with $R$, so that the redundancy $R$ plays a role that is analogous to diversity.
• Figure 3: Structural diagram of MASH. Here, the UE message signal $\mathbf{S}\xspace$ consists of pilots $\mathbf{S}\xspace_T$ (shown in red) and data symbols $\mathbf{S}\xspace_D$ (shown in blue). The jammer is a multi-antenna jammer that dynamically switches different antennas off (shown in gray) while transmitting Gaussian symbols using its active antennas (shown in green). Raising transforms the jammer into a barrage jammer.
• Figure 4: MASH (left) maps a length-$K$ signal $\mathbf{S}\xspace=[\mathbf{S}\xspace_T,\mathbf{S}\xspace_D]$ to a length-$L$ signal $\mathbf{X}\xspace$ by multiplying with $\mathbf{C}\xspace_{\parallel}\xspace$. The baselines (right) map a length-$K$ signal $\mathbf{S}\xspace=[\mathbf{S}\xspace_T,\mathbf{S}\xspace_D]$ to a length-$L$ signal by interleaving it with evenly spread zero-symbols (shown in gray) that serve as jammer training period. For the baselines, we denote the receive samples corresponding to the jammer training period, pilot phase, and data phase as $\mathbf{Y}\xspace_J$, $\mathbf{Y}\xspace_T$ and $\mathbf{Y}\xspace_D$, respectively. These matrices are the non-MASH counterparts of $\bar{\mathbf{Y}\xspace}_J,\bar{\mathbf{Y}\xspace}_T$ and $\bar{\mathbf{Y}\xspace}_D$ in \ref{['eq:j_train']}-\ref{['eq:data']}.
• Figure 5: Bit error rate (BER) performance of the different MASH receivers and baselines for eight different types of jammers.

Theorems & Definitions (3)

• Definition 1: Barrage jammer
• Proposition 1
• Theorem 1