A Proposal for the Frame Structure of a Control and Non-Payload Communication Link for Unmanned Aircraft in C-Band

Abstract

It is a well-accepted notion that unmanned aircraft (UA) systems will play a major role in the future air transportation system. This is supported by market studies predicting UA growth in the order of 90% until the year 2020 [1]. Since there is no pilot aboard an unmanned aircraft and the three fundamentals of aviation - aviate, navigate, communicate - still hold, a robust control data link between the aircraft and its remote pilot is required. In the ground-to-air direction the data link has to convey flight trajectories and commands from the remote pilot to the aircraft. In the air-to-ground direction position records, telemetry data, and weather information have to be downlinked. An important design criterion for a UA control data link is the expected overall data throughput, its structure, and its distribution. ITU published a comprehensive analysis of the expected data throughput of unmanned aircraft in [2]. However, this information has not been used for an overall system design so far. The objective of this paper is to present a technical design concept for a control data link for unmanned aircraft on the basis of the published ITU requirements. Our design supports partially autonomous medium-sized and large UAs remotely guided beyond visual line of sight in non-segregated airspace. On the physical layer we propose a cellular system in the C-band based on our previous work [3]. On top of the physical layer we developed a frame structure designed to support the expected data traffic and the expected UAs density. We call our technology proposal the C-band Digital Aeronautical Communication System (CDACS). [1] The Economist, Standage, Tom, online: https://www.economist.com/news/technology-quarterly/21723003-most-drones-today-are-either-cheap-toys-or-expensive-weapons-interesting [2] ITU-R M.2171 [3] D. M. Mielke, "C-band digital aeronautical communication for unmanned aircraft systems," 2017 IEEE/AIAA 36th Digital Avionics Systems Conference (DASC), St. Petersburg, FL, 2017, pp. 1-7