# Blind Channel Separation in Massive MIMO System under Pilot Spoofing and Jamming Attack

## TL;DR

This paper proposes a novel blind channel separation method for massive MIMO systems to counter pilot spoofing and jamming attacks, analyzing the empirical distribution of received signals and demonstrating effective separation through theoretical and simulation results.

## Contribution

The paper introduces a new two-step blind channel separation technique based on empirical distribution analysis, effective against unknown and correlated pilot attacks.

## Key findings

- The method accurately separates channels under various attack strategies.
- Theoretical analysis confirms the asymptotic behavior of the empirical distribution.
- Simulation results demonstrate robust performance in realistic scenarios.

## Abstract

We consider a channel separation approach to counter the pilot attack in a massive MIMO system, where malicious users (MUs) perform pilot spoofing and jamming attack (PSJA) in uplink by sending symbols to the basestation (BS) during the channel estimation (CE) phase of the legitimate users (LUs). More specifically, the PSJA strategies employed by the MUs may include (i) sending the random symbols according to arbitrary stationary or non-stationary distributions that are unknown to the BS; (ii) sending the jamming symbols that are correlative to those of the LUs. We analyze the empirical distribution of the received pilot signals (ED-RPS) at the BS, and prove that its characteristic function (CF) asymptotically approaches to the product of the CFs of the desired signal (DS) and the noise, where the DS is the product of the channel matrix and the signal sequences sent by the LUs/MUs. These observations motivate a novel two-step blind channel separation method, wherein we first estimate the CF of DS from the ED-RPS and then extract the alphabet of the DS to separate the channels. Both analysis and simulation results show that the proposed method achieves good channel separation performance in massive MIMO systems.