Wi-Fi signals can help count people in a crowd

Washington: A Wi-Fi signal can be used to count the number of people in a given space, leading to diverse applications such as energy efficiency to search-and-rescue operations. Researchers from University of California-Santa Barbara have shown that wireless signals can do more than just providing internet access.

This approach does not require people to carry Wi-Fi-enabled devices for them to be counted. To accomplish this feat of people-counting, the researchers put two Wi-Fi cards at opposite ends of a target area. Using only the received power measurements of the link between the two cards, their approach can estimate the number of people walking in that area.

So far, they have successfully tested with up to nine people, including in both indoor and outdoor settings. The presence of people attenuates the signal in the direct line of sight between the Wi-Fi cards if a person crosses the line of sight