Analysis of confidential large-scale antenna systems

Abstract

The physical-layer (PHY) security has been increasingly studied as a rising approach to enhance the security of wireless systems in addition to the extensively applied cryptographic strategy. This manuscript considers the issue of PHY security behavior in the downlink of large scale arrays. The adopted scheme is based on a maximum ratio precoder for the data signal and artificial noise that can be forced in the null-space of the legitimate streaming links to upset the co-ordinated eavesdroppers. We focus on the quantitative investigation of the average secrecy capacity in terms of illegal users’ number, transmit antenna number, and allocated power fraction to the legal user. Also, we address the feature of the average secrecy capacity in case of channel knowledge imperfection in some detail. We notice that increasing illegal users’ number and deviation of channel information degrades the security performance while increasing Alice’s transmitting antennas can significantly compensate for this performance deterioration. Besides, power management between information and AN plays a vital role in the secrecy to be guaranteed with the aforementioned circumstances.