A Secure Transmission Scheme Based on the Twice Channel Estimation for the Pilot Contamination

This paper proposes a secure transmission scheme based on the twice channel estimation in a three- node MIMO system according to the malicious pilot contamination. Firstly, the pilot transmission length is divided into two segments during the reverse training stage and the legitimate receiver allocates all the power to one arbitrary segment for transmitting the pilot. Then, the transmitter obtains the approximate estimation of the eavesdropping channel and an erroneous CSI of the main channel based on the twice channel estimation. After eliminating the eavesdropping channel from the erroneous CSI, the transmitter transmits both the signal and the artificial noise based on the modified CSI to ensure the transmission. Finally, the simulation results show that the proposed scheme significantly improves the security performance.