WiMAX takes off at airports

WiMAX is set to make its commercial debut at airports, updating manifests, flight plans and onboard entertainment each time a plane lands.
The WiMAX-based technology hardware GateSync will be manufactured by Thales Avionics Inc., use wireless software from Proximetry Inc., and a beam-steerable phased-array antenna from Pinyon Technologies Inc.

"Our GateSync software will bring airliner information-updating into the 21st century," said Michael Sanderson, director of engineering at Proximetry. "Instead of sneaker-net, WiMAX will begin updating onboard information wirelessly as soon as each plane lands."

Airlines currently use "sneaker-net" to update onboard manifests, flight plans and in-flight entertainment files with a person wearing sneakers carrying either a laptop or a stack of tapes to each plane after it lands and physically uploads the necessary information into airliners' computers. By using WiMAX, airliners can automatically sync their onboard computers via GateSync software running on Thales Avionics ground-based computers.

"GateSync automatically syncs up all the necessary information using a WiMAX transmitter and Pinyon antenna array," said Sanderson, "[a]nd even if it does not get all of its in-flight entertainment downloaded before takeoff, the base stations at the next airport will pick up where it left off."

Backup radios
For use in airports not yet wired for WiMAX, Thales Avionics's transmitter hardware has two fall-back radios: one using Wi-Fi and another using regular packet protocols over a cell-phone connection. GateSync also has the ability to finish synching its flight computers by cross-loading from other planes on the tarmac.

Proximetry says it designed the Pinyon's slot-based beam-steerable phased-array antenna for the WiMAX transceivers because it provided more range and higher gain and came in a zero-drag form factor.

"We like the Pinyon antenna both because of its superior performance, compared to conventional antennas, and its form factor, which allows us to mount it on aircraft without penetrating the air frame, something that is not possible with conventional antennas that must be mounted outside the aircraft, thereby creating drag, which translates into extra fuel cost," said Sanderson.

Two of Pinyon's 3.5- x 5-inch beam-steerable antennas will be mounted inside an unused aircraft window either in the cockpit or in the food preparation areas, allowing it to beam information through the window rather than from an externally mounted antenna.

"There are other companies experimenting with a similar synching technology using satellites instead of WiMAX," said Sanderson. "The disadvantage there, besides having to pay for time on the satellites, is that the antenna weights nearly 500 pounds and must be mounted outside the aircraft, where it will create drag that cuts down on fuel efficiency."

WiMAX vs. Wi-Fi
According to Proximetry, Wi-Fi could also be used, but WiMAX has greater range, allowing its ground-based antennas to be located at the edge of airport grounds. Furthermore, WiMAX handles multipath interference better and has faster upload speeds.

"Others are trying to do same thing with Wi-Fi, but we couldn't get reliable download times with Wi-Fi, plus we had conflicts with local users of Wi-Fi and with the airport authorities that control the areas around the terminals," said Sanderson, "[w]hereas with WiMAX, we can mount our ground-based base stations in airlines' buildings or at the edge of the airport grounds, where the cell-phone antennas that surround airports are installed today."

According to Proximetry, an airliner will typically download 500Gbits of data while on the ground. WiMAX's reliability and lack of interference allow GateSync to reliably and accurately predict just how long each upload will take.

"Unlike [with] Wi-Fi, which you have to share with other users, when delivering content with WiMAX, we can very accurately and reliably predict each upload time," said Sanderson.

GateSync is currently at the prototype stage; ongoing testing is underway at several U.S. airports. Federal Communications Commission (FCC) certification for the radio equipment is expected by the end of 2008.

- R. Colin Johnson
EE Times