LAUSR

We present a secure transmission method for orthogonal frequency division multiplexing (OFDM) signaling between legitimate nodes (Alice and Bob) communicating in time-division duplex (TDD) mode under an active attack. An active eavesdropper carries out pilot contamination attack in pilot phase by transmitting the pilot signal of the legitimate user and jamming attack in data phase. In the proposed method, Alice estimates the reciprocal channel between Alice and Bob by employing successive cancellation of the pilot contamination and interference from an active eavesdropper in pilot and data phases, respectively. We estimate reciprocal channels of legitimate users and eavesdropper. The precoder design at Alice from the estimated channels steers information towards Bob and artificial noise towards Eve in order to enhance the secrecy capacity of channel of the legitimate nodes. The simulation results show that the proposed method effectively estimates the channels of legitimate users and eavesdropper by removing the impact of contamination attack. Consequently, legitimate channel achieves higher secrecy capacity.