Well, I don't know if is the entire world. In some regions there is no fixed antenna to provide these "errors" about measures. I my case, for example, my robot have to be near enough to "trust" in that antenna. There is a minimum area that you have to be for use the fixed antenna. The further away you are from the antenna, the data loses the desired precision.
But, my doubt is not if is entire world, is the architecture that I'm trying is correct. I know that I have an antenna near enough to download data from there and use RTK.