Secure Transmission in Cell-Free Massive MIMO With RF Impairments and Low-Resolution ADCs/DACs

This paper considers the secure transmission in a cell-free massive MIMO system with imperfect radio frequency (RF) chains and low-resolution analog-to-digital converters (ADCs) digital-to-analog (DACs) at both access points (APs) legitimate users, where an active eavesdropper attempts to wiretap confidential data. The Gaussian RF impairment model (GRFIM) additive quantization noise (AQNM) are used evaluate impacts of impairments low resolution ADCs/DACs, respectively. analytical results linear minimum mean square error (MMSE) channel estimation show that there is nonzero floor on respect impairments, ADC/DAC precision pilot power which different from conventional case perfect transceiver. Then, tractable closed-form expression for ergodic secrecy rate obtained key parameters, such as antenna number per AP, AP number, user quality factors chain, signal eavesdropper, etc. Moreover, compensation algorithm between components inexpensive coarse ADCs/DACs also presented. Finally, numerical provided illustrate efficiency achieved expressions devised algorithm, effects performance.