The multi-antenna eavesdropper scenario based on a mixed-precision analog-to-digital converter massive MIMO (Multiple Input Multiple Output) relay system is studied

where the relay amplifies and forwards the received signal. Using maximum ratio to combine the received signals at the base station

the expressions of spectral efficiency of legitimate users and eavesdroppers are derived

and the expression of secrecy spectral efficiency of the system is obtained. Based on the definition of energy efficiency

a power consumption model is established. The expression of secrecy energy efficiency is derived. And the tradeoff between the secrecy spectral efficiency and the secrecy energy efficiency is analyzed. It further reveals the influence of parameters such as the number of base station antennas and the number of ADC (Analog-to-Digital Converter) quantization bits on the physical layer security performance. The simulation results show that as the number of eavesdropper antennas increases and eavesdropping energy increases

the secrecy spectral efficiency will decrease. When the number of ADC quantization bits is 4

it can also obtain a higher secrecy energy efficiency

while ensuring the secrecy spectral efficiency.