On detection of pilot contamination attack in multiple antenna systems

In a TDD multiple antenna system, the CSI can be acquired using reverse training. A pilot contamination attack occurs when during the training phase, an adversary also sends identical pilot (training) signal as that of the legitimate receiver. This contaminates the channel estimation phase and can alter the legitimate beamformer/precoder design, facilitating eavesdropping ("pilot contamination attack"). A similar contamination occurs when an adversary with a full-duplex terminal amplifies and forwards legitimates receiver´s signal ("spoofing relay attack"). We propose superimposing a random sequence on the training sequence at the legitimate receiver, allowing use of source enumeration methods to detect pilot contamination attack. A similar strategy also detects the spoofing relay attack. The proposed method is analyzed and its detection performance is illustrated via simulations.