Outage Probability Analysis of Uplink Cell-Free Massive MIMO with User Mobility

Abstract

Cell-free massive multiple input and multiple output (CF-mMIMO) communication is the one of candidate technologies for the sixth generation (6G) wireless communication systems, as it has the ability to manage inter-cell interference in MIMO systems. In this paper, we consider a CF-mMIMO system that comprises a central processing unit (CPU), a large number of distributed access points (APs), each equipped with a multiple number of antennas, and arbitrarily distributed multiple single-antenna user equipment (UEs). Each AP is assumed to serve a fewer number of UEs. This system approach provides higher spectral efficiency (SE) and energy efficiency (EE) while offering the uniform quality of service (QoS) to all the UEs despite its low-complexity signal processing. Incorporating the practical scenarios of imperfect channel state information (CSI) and the mobility of the UEs using various types of Doppler power spectra models, we derive the closed-form expression for the outage probability (OP) in the uplink of the CF-mMIMO system considering Welch-Satterthwaite approximation. Finally, we validate the correctness of the derived expressions through numerical simulations.