Hi
When you switch on the mobile during the flight your mobile instrument try to locate the nearest base station and it will radiate more energy compared, when you are on the ground. Whenever your mobile is out of coverage area it radiates more energy to gain access to the nearest tower. Research showed that this radiation or interference from the mobiles affects the avionics particularly during take offs and landings and its been proved that because of this interference the aircraft have been deviated from the ILS system.
The future system consists of a Pico Cell installed onboard the aircraft which collects all the signals and process it with the help of onboard servers and send it back to the earth station through satellites.
If you are more intrested visit
http://www.onair.aero/en/index_en.asp