Secure Massive MIMO Transmission With an Active Eavesdropper

• Published in: IEEE transactions on information theory Vol. 62; no. 7; pp. 3880 - 3900
• Main Authors: Wu, Yongpeng, Schober, Robert, Ng, Derrick Wing Kwan, Xiao, Chengshan, Caire, Giuseppe
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antennas; Asymptotic properties; Channels; Contamination; Covariance matrices; Data integrity; Data transmission; Electric noise; Electronic eavesdropping; Exact solutions; Information theory; MIMO; Pilot training; Policies; Security; Training; Transmitters; Uplink; pilot contamination attack; Massive MIMO; secure communication
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2016.2569118

In this paper, we investigate secure and reliable transmission strategies for multi-cell multi-user massive multiple-input multiple-output systems with a multi-antenna active eavesdropper. We consider a time-division duplex system where uplink training is required and an active eavesdropper can attack the training phase to cause pilot contamination at the transmitter. This forces the precoder used in the subsequent downlink transmission phase to implicitly beamform toward the eavesdropper, thus increasing its received signal power. Assuming matched filter precoding and artificial noise (AN) generation at the transmitter, we derive an asymptotic achievable secrecy rate when the number of transmit antennas approaches infinity. For the case of a single-antenna active eavesdropper, we obtain a closed-form expression for the optimal power allocation policy for the transmit signal and the AN, and find the minimum transmit power required to ensure reliable secure communication. Furthermore, we show that the transmit antenna correlation diversity of the intended users and the eavesdropper can be exploited in order to improve the secrecy rate. In fact, under certain orthogonality conditions of the channel covariance matrices, the secrecy rate loss introduced by the eavesdropper can be completely mitigated.