Google+ Consumer Psyche: The Economist explains How airborne Wi-Fi works

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Tuesday, February 24, 2015

The Economist explains How airborne Wi-Fi works

AN ALWAYS-connected lifestyle is a blessing for some and a nightmare for others. Aeroplanes used to be the one respite in a typical business traveller's itinerary—a place to escape from the e-mails and phone calls for a few hours, and perhaps even have some good ideas. (Travellers with long memories might remember seatback phones in some countries that allowed exceedingly expensive, poor-quality in-flight phone calls; fortunately, nobody ever used them.) Starting in the early 2000s, however, this blissful seclusion started to come under threat, as airlines started to provide internet service at 10,000 metres. In-air Wi-Fi is now increasingly common on domestic routes in America, and on long-haul routes elsewhere. Given that many routes fly largely over water or over uninhabited areas, how do you connect an aeroplane to the internet?

Delivering radio signals to a plane is nothing new, but the usual ways of doing it involve low-bandwidth links that would be painfully inadequate for internet traffic. Voice communication remains analogue, even in the digital age. The Aircraft Communications Addressing and Reporting System (ACARS) provides digital links via VHF signals from the ground, or via satellites, allowing planes to send brief bursts of telemetry information. But ACARS operates at data rates comparable to dial-up models, measured in thousands of bits per second (Kbps). These voice and telemetry systems are designed for international compatibility, reliability and resilience. In-flight internet requires something much more zippy, but with less of a requirement that everything must work perfectly at all times. Two approaches have emerged, one based on ground-to-air links and the other on satellites.

Boeing led the first efforts in the early 2000s, leasing dedicated transponder capacity on geostationary satellites that appear to hover at a fixed point in the sky, and designing an enclosure (or "radome") to be retrofitted on top of its aircraft, and those made by other firms. Its Connexion service provided suitably equipped aircraft with an internet link running at a few megabits per second (Mbps), divvied up among passengers. Boeing also had to retrofit Wi-Fi (and, in some cases, Ethernet cabling) inside planes. But the service never became financially viable, in part because of the high cost of installing and operating the equipment, and Boeing discontinued it in 2006. That same year another firm, now called Gogo, purchased a thin sliver of air-to-ground spectrum in the United States, and began service in 2008, deploying dozens of ground stations that point upwards at aircraft, rather than downwards at people on the ground, and use a variant of 3G mobile-data technology called EV-DO. Service was extended to Canada in 2014. This provides enough bandwidth for e-mail and basic web browsing; Gogo blocks both streaming video and internet telephony to ensure that one user cannot hog all the capacity.

But satellite never entirely went away. After Boeing's early, failed attempt, satellite equipment became lighter, cheaper and more capable, and newer planes are designed to accommodate Wi-Fi gear. Several firms now operate in-flight internet service via satellite; some own the satellites, like Panasonic Avionics (United's contractor for its newer internet service), while others, such as Row 44 and OnAir, license the necessary capacity. Gogo has added satellite-based internet to its options as both a standalone new service and as part of a hybrid service that combines, where available, ground and satellite transmission. Meanwhile, speeds are poised to skyrocket as satellite operators expand service from the lower-frequency Ku band to the higher-frequency Ka band. Data rates should jump from a maximum of roughly 10Mbps to 50-80Mbps per plane. And America's telecoms regulator will auction 500MHz of ground-to-air bandwidth in the near future, which could allow connection speeds of up to one gigabit per second for planes travelling over land. Travellers who worry about feeling out of touch while airborne will welcome these improvements. Those who prefer being disconnected can take solace in the fact that thousands of aircraft worldwide still remain unconnected—for the time being, at least.

Original article is from here.
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