Signal Authentication against Spoofing Attacks on Aircraft Automatic Dependent Surveillance-Broadcast Signals

Automatic Dependent Surveillance - Broadcast (ADS-B) transmissions from aircrafts are one of the most important signals for passive surveillance and monitoring of aircraft movements. The possibility of monitoring them from space has significantly increased their utility. However, these transmissions are not encrypted and follow well-established protocols. These features make the transmissions vulnerable to various attacks, spoofing attack being the most complex and dangerous. The present paper proposes a methodology for authenticating the ADS-B transmission based on the transmitted signal's RF domain spatial characteristics, i.e., by the measurement of the elevation of the signal. A 3-antennaPhase Interferometer in z-direction is used for accurate elevation measurement of the genuine ADS-B signal and the spoofing signal on a pulse-by-pulse basis. Ambiguity resolution of the measured modulo 2π phase measurements is detailed and simulation results presented for the achievable accuracy.