The Inventors’ approach is based on the observation that a very wideband radio (e.g. a few GHz) can allow time-of-flight measurement at sub-nanosecond accuracy. While each Wi-Fi frequency band is only tens of Megahertz wide, there are many such bands that together span a very wide bandwidth. Their solution therefore collects measurements on multiple Wi-Fi frequency bands and stitches them together to give the illusion of a wide-band radio. Their key contribution is an algorithm that achieves this, despite the fact that Wi-Fi frequency bands are non-contiguous, and in some cases, a few Gigahertz apart.
Chronos is a software-only solution that demonstrates the performance and practicality of their design by harnessing these algorithms to enable a pair of commercial Wi-Fi devices to locate each other without any support from the infrastructure. Chronos may be applied to personal drones that follow a user around and capture videos of their everyday indoor activities. Such drones can help monitor fitness, activities and exercise of users at home, work or the gym. Chronos allows a personal drone to maintain the best possible distance relative to its user to take optimal videos at the right focus. It achieves this by using the Wi-Fi card on the drone to locate the user’s device.