In the article the say accuracy is coming down to 1m vs 3-5 for other GPS

With military receivers (or codeless phase tracking) the current constellation is good down to centimeters.

This isn't possible without third party data. Things like the refractive index of the atmosphere (which depends on weather patterns), and the fact orbits are slightly warped due to varying gravitational fields and radiation pressure from the sun, all add up to location innacuracies unless you can correct for these effects.

That correction requires data, which needs to come from a third party because the satellites don't transmit it.

Correct, if only L1 is used. However as GPS exists today receivers can track phase variations between L1 and L2 without the codes necessary to decode the signal on L2.

Actually its a bit more sophisticated. Galileo ground stations measure their reported position against the actual, and then transmit correction data to the satellites which then retransmit it with the rest of the position data.

Groundbased gps transmitters might help to increase accuracy.

> In the article the say accuracy is coming down to 1m vs 3-5 for other GPS

In which areas?

> As of June 28, Chinese satellites were observed more frequently than GPS satellites in 130 of 195 countries (U.N. member states plus the Vatican and Palestine). More than 20 BeiDou satellites were observed over mainland China.

I don't get something you have satellites of glonass, gps and beidou what's stopping anyone from getting better accuracy using all 3 at the same time.

because they are independent systems; they cannot communicate triangulation data between themselves

Isn't the triangulation being done on the phone/device GPS chip ? The same chip is doing it for all 3 services. The chip gets the data of the satellite positions and then shows its location in relation to them that how I thought gps/other systems worked.