Re: If geostationary worked so well
The GSO satelites don't provide navigation in themselves. the problem with GSO, apart from it being a jolly long way away and so needing rather beefy signals, is that the satelites are all in a line so the position solution is rather crap.
This proposal, like WAIS and EGNOS, simply rebroadcast extra information (time and correction) sent from the ground, to all the users of the regular system to improve their position. Not to mention confidence in the position, the original driver for WAIS was the FAA wanting to replace ground beacons but wanting aircraft to have some way of detecting GSP errors
You can do a much better job sending corrections from the ground with more locality, but the advantage of GSO is that a single satelite broadcast can cover a big chunk of the continent.