Downlink Performance Analysis of Cell-Free Massive MIMO over Spatially Correlated Rayleigh Channels

With the increasing number of users in 5G communication, the need for faster and higher speeds becomes more urgent, cell-free massive multiple-input multiple-output (mMIMO) is seen as the most promising technology to solve the problem. The main purpose of this paper is to study the downlink spectral efficiency (SE) of cell-free mMIMO under different power control and precoding schemes over spatially correlated Rayleigh fading channels. The simulation results show that cell-free mMIMO has better downlink performance than cellular mMIMO. In addition, in order to further improve the performance of cell-free mMIMO, we also propose the ad-hoc enabled cell-free mMIMO architecture. Simulation results show that in the proposed ad-hoc enabled cell-free mMIMO architecture, the 5% outage rate increases from 1.04 bit/s/Hz of the original model to 2.82 bit/s/Hz. Moreover, compared with cellular mMIMO, ad-hoc architecture has significant SE improvement.