Performance Analysis of Cell-Free Massive MIMO System with Low-Resolution ADCs Under Rician Fading Channels

‍ ‍The cell-free massive multiple-input multiple-output （MIMO） system is regarded as one of the key technologies in future 6G communications. However， with the rapid increase in the number of access points （APs） and users， the issue of hardware costs has become an important factor restricting the development of the cell-free massive system. In order to effectively reduce the hardware cost， we can consider configuring low-resolution analog-to-digital converters （ADCs） on the AP and the user. For these reasons， this paper focuses on cell-free massive MIMO system with low-resolution ADCs under Rician fading channels. Leveraging on the additive quantization noise model， the closed-form expression of achievable rate of this system is derived for conjugate beamforming precoding， which enables the study of effects of AP number， the resolution of ADC and Rician K-factor on the achievable rate. Moreover， a power control algorithm is proposed to maximize the sum achievable rate， subject to each user of quality-of-service constraint and each AP of power constraint. Finally， simulation results demonstrate that compared with the case of no power control algorithm， the proposed algorithm can bring greater performance gain.