Understanding Inflight WiFi’s Poor Performance

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Within just a couple of years, inflight WiFi has moved from a luxury to a near commodity for most continental flights. Prices for the service range as widely as their apparent performance. In one extreme, JetBlue recently announced it will make WiFi available for free. With other airlines, a monthly access plan can set you back as much as $50.

“That’s the same price as a month of broadband access at home,” said Northwestern Engineering’s Fabián Bustamante. “And, during a flight, the connection is more similar to dial-up.”

Bustamante, who is a professor of computer science at Northwestern’s McCormick School of Engineering, and his team are working to better understand the systems challenges for inflight WiFi. They expect this could lead to new approaches for improving current consumer service and potentially revolutionize the antiquated communication services that support the global air-traffic management system.

The team will present its preliminary work and their vision for such changes on Tuesday, February 23 at the 17th annual International Workshop on Mobile Computing Systems and Applications in St. Augustine, Florida. John Rula, a PhD student in Bustamante’s lab, is lead author of the study. The work was done in collaboration with David Choffnes, assistant professor of computer science at Northeastern University and an alumnus of Bustamante’s lab.

Since first appearing in late 2004, inflight WiFi has grown to become an important component of airlines’ revenue. A recent Honeywell survey found that 85 percent of passengers used inflight WiFi from 2013 to 2014, and 66 percent of them selected flights based on WiFi availability.

While the idea of inflight WiFi has rapidly become popular, the complaints about the quality of existing services have also increased. Bustamante’s team has built an application called Wi-Fly that measures Internet connectivity during flights. Using this application, Bustamante and his team have found that inflight WiFi is slower than using a dial-up modem. Loading a single webpage, in fact, often took an excruciating 30 to 35 seconds.

“This is not particularly surprising,” Rula said. “Flying presents one of the most challenging conditions for continuous WiFi activity because the flights are six miles in the air. They are moving at 500 to 600 miles per hour. From a network perspective, that’s incredibly challenging.”

Typical inflight WiFi configurations include multiple WiFi access points connected to an onboard server, which is linked to the ground via satellite or cell towers. Both options require the signal to travel over great distances before bouncing back to mobile devices on the airplane. When cell towers are not nearby — such as when flying over an ocean — connectivity is even worse, if not impossible.

Bustamante and his team hope that new, crowdsourced data can offer a deeper understanding of the quality of service experienced by customers, their main problems, and potential solutions. After purchasing inflight WiFi, passengers can access the Wi-Fly site to receive a live view of the performance they experience, which is mapped over their route. At the same time, they can contribute valuable data to Bustamante’s research.