I was thinking about something like this, about 25 years ago.  But rather than a free-flying balloon, I felt that an aerostat configuration would be better.  Further, I figured that a bidirectional optical fiber link would be useful, such as:  http://datainterfaces.com/sfp-modules-single-strand-bidirectional-gigabit-SC.aspx?gclid=CjwKEAjw-IOwBRD1wrTC27fSjFISJABUDZ17VgezJOQe9_0o3_9WJIWBYvqkpJyge7-5g3ZkgT4wZBoC1vzw_wcB

An otherwise-unjacketed optical fiber, but with a woven Kevlar strength covering, would be useful.  

Obviously, the FAA wouldn't approve, but that doesn't keep us from imagining, huh?  

            Jim Bell.