Sum Rate Analysis and Power Allocation in Massive MIMO Communications with Aerial and Terrestrial Users

Massive multiple-input multiple-output (Massive MIMO) technique provides the ability to communicate with numerous users by spatial multiplexing. With wide applications of unmanned aerial vehicles (UAV), there are terrestrial users coexisting with aerial users in a cell. The channels between ground base station and aerial users include a lot of Line-of-sight (LoS) paths, which is different with rich scattering channels of ground users. In this article, the time division duplex (TDD) Massive MIMO with uplink channel estimation and downlink transmission is investigated under the frame of Orthogonal Frequency Division Multiplexing (OFDM). The system sum rate is analyzed with consideration of channel estimation errors. A power allocation scheme which utilizes the different channel delay spread of aerial and terrestrial users is proposed to maximize the sum capacity.