We are working with NextNav to enhance the security of their Terrestrial PNT (Position, Navigation and Timing) system, known as Metropolitan Beacon System (MBS). Our goal is to detail effective strategies that exploit the unique advantages of MBS for enhanced security against RFI (radio-frequency interference) threats.

GNSS applications have revolutionized modern life both in the open, outdoor environment, and more recenetly in the closed, deep-urban environments. However, GNSS signals remain  out of reach in the indoor environment, due to the inherent weakness of GNSS signals. MBS addresses this gap by providing accurate geolocation in an indoor environment using a network of synchronized beacons that serve the same purpose as the satellites of GNSS.

MBS and GNSS are both vulnerable to unintentional or malicious RFI.  However, some aspects of MBS offer opportunities for novel security measures. The latest cryptographic defense techniques can be applied to the MBS waveform without being constrained by the need of backward compatibility. Mutual observability using signal multiplexing and bi-directional communication between adjacent beacons will augment the system with secure time synchronization, integrity monitoring, and autonomous jammer/spoofer detection and localization capabilities. These capabilities will render MBS more secure and resilient than GNSS against RFI threats.

Mbs Security