BPS is a GPS alternative that nobody's heard of
jeffgeerling.comInteresting just in case system. Hybrid of both GPS and BPS for extra accuracy might have benefits. But from [2 - page 13] four transmission towers, accuracy is within 100 m.
[1] https://nabpilot.org/broadcast-positioning-system-bps/
[2] https://www.gps.gov/cgsic/meetings/2023/diamond.pdf [pdf]
...for timing, not for positioning
Positioning would come once more towers are working together, and based on current data, (again if it is widely deployed) could be down to centimeters.