Pilot Contamination for Active Eavesdropping
Existing studies on physical layer security often assume the availability of perfect Channel State Information (CSI) and overlook the importance of channel training needed for obtaining the CSI. In this paper, the authors discuss how an active eavesdropper can attack the training phase in wireless communication to improve its eavesdropping performance. They derive a new security attack from the pilot contamination phenomenon, which targets at systems using reverse training to obtain the CSI at the transmitter for pre-coder design. This attack changes the pre-coder used by the legitimate transmitter in a controlled manner to strengthen the signal reception at the eavesdropper during data transmission.