You'd run the whole thing over the same 2.4G/5G 20/40/80 Mhz channels as wifi, but probably using a gold-code scheme. You'd pre-arrange what code you'll use (perhaps derived from the base station mac address so there aren't collisions even across a city). Simulations would have to be done of high bandwidth close-by unencoded and low bandwidth long distance coded users coexisting, and defining a fairish sharing scheme between them.
The whole thing could probably be implemented with only custom firmware (ie. no hardware changes). All modern GPS's do below-noise-floor reception of GPS signals entirely in software - this would be the same. You might want custom hardware to avoid the rather huge power costs of leaving the main high bandwidth receivers being turned on the whole time though!
You could use the same MIMO mechanisms to get a better channel gain and increase the total amount of data users can transfer in a given city-sized area.
The whole thing could probably be implemented with only custom firmware (ie. no hardware changes). All modern GPS's do below-noise-floor reception of GPS signals entirely in software - this would be the same. You might want custom hardware to avoid the rather huge power costs of leaving the main high bandwidth receivers being turned on the whole time though!
You could use the same MIMO mechanisms to get a better channel gain and increase the total amount of data users can transfer in a given city-sized area.