Cell-Free Massive MIMO Systems With Low-Resolution ADCs: The Rician Fading Case

Abstract

This article studies the uplink and downlink achievable rates of cell-free massive multi-input multi-output (MIMO) systems over Rician fading channels, assuming that each access point possesses multiple antennas that are connected with low-resolution analog-to-digital converters (ADCs). Achievable closed-form rate expressions for both uplink and downlink are derived, which enable us to explore the design issues surrounded by the key parameters, such as the number of total antennas, the transmit power, the ADC resolution, and the Rician <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {{\it K}}$</tex-math></inline-formula> -factor. Moreover, the weighted max–min fairness power optimization algorithms are proposed. Specifically, the proposed algorithms for uplink and downlink can be formulated as geometric programming and second-order-cone programming, respectively. All the theoretical analyses and the effectiveness of the proposed algorithms are verified by simulation experiments.