Aditya Dua (dua[at]ee.iitb.ac.in)
Aman Kansal (aman[at]ee.iitb.ac.in)
Arjunan R (arjun[at]ee.iitb.ac.in)
Sumitra Ganesh (sumi[at]ee.iitb.ac.in)
Vivek Raghunathan (vivek[at]ee.iitb.ac.in))

Air passengers are required by the law to switch off their mobile phones on board any flight .This requirement has been imposed due to two reasons. First, signals emitted by the mobile phone interfere with Air Traffic Control (ATC) signals, undermining the safety of the flight. Second, a mobile at such an altitude connects to multiple base stations simultaneously, clogging the resources of the ground network. We have developed a novel solution based on the integration of diverse communication links: Bluetooth, Cellular Network (GSM/IS-95)1, PSTN and Air-to-ground connection. Our solution enables the user to remain connected inflight, while solving the above two critical issues. The switch over from the cellular network to our in-flight Bluetooth network does not require any user initiation or change of the mobile handset. Bluetooth, due to its low power, short range and fast frequency hopping presents negligible interference to ATC signals. When the passenger enters the plane, call forwarding is set up from the cellular network to our Ground Switching Center (GSC) and the hazardous GSM emissions of the mobile phone are automatically switched off. All voice (or data) is received at the GSC and transferred through an air-to-ground page link to a Bluetooth Airplane Gateway (BTAG) in the plane. Data received at the BTAG is finally transmitted over an in-flight Bluetooth network to the passenger. We have implemented a Bluetooth enabled GSM phone, (on a laptop using a GSM modem and a Bluetooth kit), the Bluetooth Airplane Gateway and the Ground Switching Center (using a phone modem for connecting to the PSTN). The automatic setup up of various communication hops, call routing and transmission of voice over these links has been demonstrated. The system provides a unique and useful service and is perceived to be highly marketable.