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University researchers have developed wireless technology that lets a single access point spot people within inches of their locations. The invention could lead to password-free Wi-Fi in cafes, safer recreational drones, and better climate control systems in homes and small offices.
Researchers at MIT call the Wi-Fi people finder Chronos. The innovation makes it possible to use only one access point (AP) to pinpoint a person within tens of centimeters. Achieving such accuracy with a single device means smaller businesses can afford to take advantage of location-based services.
"Centimeter-level accuracy for a Wi-Fi-based positioning system would indeed be a breakthrough," said Mark Hung, an analyst at Gartner.
Chronos uses a novel algorithm that turns an access point's Wi-Fi network interface card into a people locator. A Chronos-equipped AP would work in conjunction with a person's Wi-Fi-enabled mobile device or wearable.
Many enterprises use multiple APs that triangulate people's location based on the Wi-Fi frequency originating from their mobile devices. Retailers typically track people through beacon technology that utilizes the Bluetooth Low Energy protocol to communicate with customers' smartphones.
Uses for Chronos Wi-Fi people finder
A less expensive people spotter could benefit small businesses in a variety of ways. For example, Chronos could feed the number of individuals in a room to climate control systems that could use the data to adjust heating, air conditioning and lighting.
A cafe could use Chronos to restrict Wi-Fi to people in the bistro, making a customer password unnecessary. Keeping outsiders off the network would also reduce congestion.
Recreational drone makers could use the technology to make the low-altitude flying robots safer. Equipping the remotely controlled aircraft with Chronos would ensure the drone maintains a safe distance from the user.
How the Wi-Fi people finder works
Chronos calculates people's location by measuring the time it takes data to travel from a mobile device to an AP. The algorithm then multiplies the time by the speed of light to calculate distance. Data rates, which researchers refer to as time of flight, are calculated within half of one-billionth of a second.
To determine a person's location, Chronos receives several copies of a Wi-Fi signal from a mobile phone. Because the signals bounce off walls and furniture, the algorithm considers delays in receiving them before choosing the most direct path to the mobile device or wearable.
Chronos had 94% accuracy in identifying the location of four people in a two-bedroom apartment, MIT researchers said. The technology had 97% accuracy in identifying individuals inside or outside a store.
AP manufacturers, such as Cisco or Hewlett Packard Enterprise, could eventually use Chronos, said Adam Conner-Simons, an MIT spokesman. However, "there are no plans to develop such partnerships until the research is further along."
Scientists from MIT's Computer Science and Artificial Intelligence Laboratory presented their Chronos research last month at the USENIX Symposium on Networked Systems Design and Implementation.
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