Basically combo powerline data with rapidly blinking (1000+ hz, iirc) leds to be able to give specific rooms wireless data. And if the light is polarized, a simple coating on the windows that match can let light in, but not data out.
Example of what tech such optics could use:
Solid-state variable optics: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-18-13-1...
Compact non-conical optics: http://www.nasa.gov/feature/goddard/out-with-the-old-in-with...
Basically combo powerline data with rapidly blinking (1000+ hz, iirc) leds to be able to give specific rooms wireless data. And if the light is polarized, a simple coating on the windows that match can let light in, but not data out.