Implementation of Wide Area Multilateration Using a 1090 MHz ADS-B Signal

The automatic dependent surveillance-broadcast (ADS-B) and MLAT technology comprise the current and planned infrastructure of the Next Generation Air Transportation System (NextGen), respectively. MLAT can be combined with the ADS-B system as an alternate positioning navigation and timing (APNT) system based on the mature multilateration (MLAT) technology, namely, time difference of arrival (TDOA), which is utilized in wide-area multilateration (WAM) and determined using the ADS-B Mode S ES signal at a frequency of 1090 MHz. However, the position accuracy of TDOA-based WAM is affected by the geometry of the ground stations and observed measurement errors. The former requires the horizontal dilution of precision (HDOP) to be less than or equal to 2.828 in terms of aviation navigation and surveillance, which limits ground station positioning in island countries with limited real estate. To achieve adequate positioning accuracy, a suitable position algorithm based on adequate system geometry and measurement for a WAM testbed is presented and investigated. Importantly, this paper demonstrates that the established WAM positioning testbed and the obtained positioning performance using actual flight data meet the performance requirements of navigation services in terms of adequate measurement and coverage volume.