Secure transmission in one-bit cell-free massive MIMO system with multiple non-colluding eavesdroppers

This paper investigates the secrecy performance of the one-bit cell-free massive multiple-input multiple-output system in the presence of multiple non-colluding eavesdroppers (Eves), considering that access points (APs) are deployed with one-bit analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), or only one of them, or ideally infinite-resolution ones. Based on Bussgang decomposition theory and the introduction of maximum ratio transmission, artificial noise (AN) technologies, we derive closed-form expressions for achievable rates of legitimate users and upper-bound expressions for ergodic leakage information rates of Eves. We use the achievable secrecy rate to evaluate network security performance. Through theoretical analysis and numerical results under the four cases at APs , whether the resolution of ADCs or DACs is one-bit or not, we evaluate the effect of the number of APs or Eves, the number of APs’ or Eves’ antennas, the downlink transmit power, and the power fraction into signal symbols or AN symbols on the secrecy performance, respectively.