GNSSbased

GNSS-based positioning refers to methods and systems that determine a user’s position, velocity, and time using signals broadcast by global navigation satellite systems. The major constellations include GPS (US), GLONASS (Russia), Galileo (Europe), and BeiDou (China), with military and civil signals available on multiple frequencies. Modern receivers can track several satellites simultaneously, using measurements of code pseudorange and carrier phase, coupled with precise ephemeris data that describe satellite orbits and clocks. By solving a navigation equation set, the receiver estimates the user’s coordinates and clock bias.

Two common approaches to improve accuracy are augmentation and advanced processing. Real-Time Kinematic (RTK) uses carrier-phase corrections from nearby base stations to achieve centimetre-level positioning, while Precise Point Positioning (PPP) relies on precise satellite orbit and clock information, potentially using global networks, to reach sub-meter to centimeter accuracy without local references. Satellite-based augmentation systems (SBAS) like WAAS or EGNOS provide wide-area corrections and integrity information.

GNSS-based positioning is widely used in navigation, surveying, mapping, time synchronization, aviation and maritime, as well as in consumer devices and autonomous systems. Receivers are increasingly integrated with inertial sensors, cameras, or odometry for robust operation in challenging environments.

Limitations include dependence on sky visibility, multipath effects, atmospheric delays, and susceptibility to interference or spoofing. In urban canyons or indoors, accuracy degrades. Ongoing developments focus on multi-constellation support, modernized signals, and resilient positioning through networks and sensor fusion.