Power Scaling for Massive MIMO UAV Communication System

We consider the uplink of an unmanned aerial vehicle (UAV)-aided massive multiple-input-multiple-output (MIMO) communication system, wherein $K$ UAVs with single antenna elements transmit data signals to a ground station (GS) equipped with a large number $(M)$ of closely-spaced antennas. We consider a maximal ratio combining (MRC) detector at the GS and derive closed form expressions for its asymptotic spectral efficiency (SE) with $M\rightarrow\infty$ for both perfect and imperfect channel state information (CSI) for two common power scaling schemes, $1/M$ and $1/\sqrt{M}$. We numerically obtain the plots of variation of SE with $M$ for the aforementioned power scaling schemes and validate the derived asymptotic bounds for large $M$.