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<-- Cell phones on airliners
The Future of Cell Phones on Airliners by James Poll
One day soon cell phones will be usable in-flight through on-board low-power microcells. These cells will 'instruct' phones to use lower power settings for the access, page response, and call phases of a phone call. When this happens the GTE Airfones used today will become a faded memory.
The aircraft itself will contain cell site equipment plus facilities to link back to the public switched telephone network below. The airborne cell site equipment, a Pico-Cell, will be suitably engineered for on-board use on an aircraft. The phone's 'uplink' to the Pico-Cell on the aircraft would command the phone to set it's PL or Power Level (in IS-136 parlance) to 10 resulting in just milliwatts coming out of the phone. This should work to protect the terrestrial cellular network operating 30,000 feet below.
How does the on-board cellular traffic get to the ground? On their website AirCell mentions joining in a partnership with Iridium but what they seem to promote is using their ground-based cellular radios and infrastructure to serve as the link.
In their material, an excellent .pdf file called Personal Cell Phone Use Inflight (internal link: 649K), Air Cell describes this process. A network of specially equipped cell sites spaced somewhat evenly across the country would receive and transmit cell traffic from Air Cell fitted airliners. These sites already exist as part of the conventional terrestrial cellular network. But they'd need some things to work.
Aircell seems to use cellular carriers who have spectrum available and have plumbed up base station radios to antennas that have horizontal E-field patterns. That means a radiation pattern pointing 'up' (in a cone shape) rather than the usual terrestrial coverage.
Will it work? Maybe. I suppose it could be done with proper engineering. That means horizontal polarization, reduced power, and non-standard control channel frequencies to avoid 'trapping' standard public cell phones. We'll see.
Here are some good links:
http://www.wirelessweek.com/article/CA5799 (external link)
http://www.wirelessreview.com/ar/wireless_aircell_takes_off/ (external link)
<-- Cell phones on airliners
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MTS and cellular // Appendix: Call processing diagram //
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