Geraci, GiovanniGarcía Rodríguez, AdriánGalati Giordano, LorenzoLópez Pérez, DavidBjörnson, Emil2020-03-262018Geraci G, Garcia-Rodriguez A, Galati Giordano L, López-Pérez D, Björnson E. Understanding UAV cellular communications: from existing networks to massive MIMO. IEEE Access. 2018 Nov 9;6:67853-65. DOI: 10.1109/ACCESS.2018.28767002169-3536http://hdl.handle.net/10230/44042The purpose of this article is to bestow the reader with a timely study of UAV cellular communications, bridging the gap between the 3GPP standardization status quo and the more forward-looking research. Special emphasis is placed on the downlink command and control (C&C) channel to aerial users, whose reliability is deemed of paramount technological importance for the commercial success of UAV cellular communications. Through a realistic side-by-side comparison of two network deployments – a present-day cellular infrastructure versus a next-generation massive MIMO system – a plurality of key facts are cast light upon, with the three main ones summarized as follows: (i) UAV cell selection is essentially driven by the secondary lobes of a base station’s radiation pattern, causing UAVs to associate to far-flung cells; (ii) over a 10 MHz bandwidth, and for UAV heights of up to 300 m, massive MIMO networks can support 100 kbps C&C channels in 74% of the cases when the uplink pilots for channel estimation are reused among base station sites, and in 96% of the cases without pilot reuse across the network; (iii) supporting UAV C&C channels can considerably affect the performance of ground users on account of severe pilot contamination, unless suitable power control policies are in place.application/pdfeng© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. http://dx.doi.org/10.1109/ACCESS.2018.2876700info:eu-repo/semantics/articlehttp://dx.doi.org/10.1109/ACCESS.2018.2876700Unmanned aerial vehiclesUAVsCommandControl channelCellular networksMassive MIMO3GPPinfo:eu-repo/semantics/openAccess