Communicating with unmanned aerial swarm automatic dependent surveillance transponders

Abstract

Suitably equipped air traffic can be tracked by decoding its Automatic Dependent Surveillance (ADS) Broadcast (ADS-B) signal. ADS is defined by initiatives in the U.S. through the NextGen program and in Europe through the SESAR program. ADS-B surveillance service in the U.S. comprises of the 1090 Extended Squitter (1090ES) that operates on 1090 MHz and the Universal Access Transceiver that operates on 978 MHz (978UAT). While 1090ES is used commercially and worldwide, UAT is a regional system used extensively in the U.S. for aircraft operating below 18000 ft. Since the ADS-B message contains aircraft state and intent information, ADS-B is a potential method for communication, navigation and surveillance of unmanned aerial systems (UAS) operating in low altitude. This paper describes and demonstrates a simulation tool developed to model ADS-B communication from UAS as a function of UAS and manned aircraft traffic, power of transmission, range between aircraft and operators, ping rate, maximum latency of aircraft state communication and required reliability of state information. Communication success is degraded with distance and due to collision with other ADS-B packets emitted by nearby aircraft in Mode S, A and TCAS, while broadcasting or communicating to different ground stations (False Replies Unsynchronized In Time or FRUIT). The model and its results on surveillance sensitivity to key parameters, are expected to inform the NASA UAS Traffic Management research, about the benefits and limitations of ADS-B utilization for high density UAS operations.