More precision would require an atomic (hydrogen or cesium) clock on each satellite, and periodic adjustments for relativistic effects, just like regular GPS an

More precision would require an atomic (hydrogen or cesium) clock on each satellite, and periodic adjustments for relativistic effects, just like regular GPS and other GNSS systems. An intermediate improvement might be a small/lightweight rubidium clock synced to GPS to improve stability for when GPS is unavailable to the satellite.