Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have created a system called Chronos that enables a single WiFi access point to locate users to within tens of centimeters, without any external sensors. The system could mean safer drones, smarter homes, and password-free WiFi. The group demonstrated Chronos in an apartment and a cafe, while also showing off a drone that maintains a safe distance from its user with a margin of error of about four centimeters. Existing localization methods have required four or five WiFi access points. This is because today’s WiFi devices don’t have wide enough bandwidth to measure time-of-flight, and so researchers have only been able to determine someone’s position by triangulating multiple angles relative to the person. What Chronos adds is the ability to calculate not just the angle, but the actual distance from a user to an access point, as determined by multiplying the time-of-flight by the speed of light.