Adaptive Air-to-Ground Secure Communication System based on ADS-B and Wide Area Multilateration

A novel Air-to-Ground (ATG) communication system, based on adaptive modulation and beamforming enabled by Automatic Dependent Surveillance-Broadcast (ADS-B) and multilateration technique is presented in this work. From an aircraft geolocation perspective, the proposed multilateration technique uses the Time-Difference-of-Arrival (TDOA), Angleof- Arrival (AOA), and Frequency-Difference-of-Arrival (FDOA) features within the ADS-B signal to implement the hybrid geolocation mechanism. Moreover, this hybrid mechanism aims at the optimal selection of multilateration sensors to provide a precise aircraft geolocation estimate by minimizing the Geometric Dilution of Precision (GDOP) metric and also imparts significant resilience to the current ADS-B based geolocation framework to withstand any form of attack involving aircraft-impersonation and ADS-B message infringement. From an ATG communication perspective, the ground Base Stations (BSs) can use this hybrid aircraft geolocation estimate to dynamically adapt their modulation parameters and transmission beampattern, in an effort to provide a high data rate secure ATG communication link. Additionally, we develop a hardware prototype which is highly accurate in estimating the AOA data and facilitating TDOA, FDOA extraction associated with the received ADS-B signal. This hardware setup for the ADS-B based ATG system is analytically established and validated with commercially available universalsoftware- defined-radio-peripheral (USRP) units. This hardware setup displays a 1.5??? AOA estimation accuracy, whereas the simulated geolocation accuracy is approximately 30 m over 100 nautical miles for a typical aircraft trajectory. The adaptive modulation and beamforming approach assisted by the proposed GDOP minimization based multilateration strategy achieves significant enhancement in throughput and reduction in packet error rate.