L-Band Commercial Communications Service for Unmanned Aircraft Systems

Significant effort is being expended defining the requirements for unmanned aircraft to fly in the National Airspace System (NAS). The goal is for an unmanned aircraft to be able to file a flight plan and fly in the NAS with no more restrictions than those imposed on a manned aircraft. The result would be unmanned and manned aircraft flying together in the same airspace. Before this can occur, an unmanned aircraft must demonstrate that it can safely mingle with manned aircraft. The aircraft, control station and other components of the unmanned aircraft system (UAS) must complete the FAA´s certification process, which determines that the UA can operate safely in the NAS. A key component of safe operations is communications. The pilot must be able to receive telemetry data from the aircraft and send commands to it. This is accomplished via a data link (the control link). In addition, he/she must be able to communicate with air traffic controllers who are using VHF voice radios to provide instructions to aircraft. In many cases the aircraft will relay the VHF voice traffic between the controller and the pilot. The communications path for the relay will be a data link between the aircraft and the pilot -referred to as the ATC communications link. A key element in getting a UAS certified will be demonstrating that the ATC communications and the Control links meet required communications performance (RCP) requirements. This paper explores the concept of a commercial organization providing the data link service needed for the UAS ATC communications and control links in the continental United States. The service provider would supply access nationwide and use aviation-protected spectrum in L-band. A concept of operations is presented along with a discussion of link access, protocols, and bandwidth limitations.