Depends on what you define as 'traditional': basically if you want positioning information via GNSS, the techniques for getting a better reading a fairly well understood, and it doesn't really matter how good your satellites are, the atmospheric distortion is the issue and you need to model and compensate for it by measuring it with a near-enough base station, using multiple frequencies and constellations, and if you're moving, an IMU to constrain your motion over as long a period as you can to effectively average out the other noise sources. Half a centimeter, given all of the above, is better than what I've seen quoted in the space, but not utterly crazily so.