Crowd-counting WiFi technique looks through walls

Devised by a group at the University of California Santa Barbara, the technique could have applications in smart energy management, retail business planning and security. “Our proposed approach makes it possible to estimate the number of people inside a room from outside,” said Prof Yasamin Mostofi, who led the research.

Presented at the  2018 IEEE International Conference on Sensing, Communication, and Networking (SECON) the technology uses WiFi RSSI (received signal strength) measurements to estimate the number of people.

In the team’s experiments, one WiFi transmitter and one WiFi receiver were placed behind walls, outside a room in which up to 20 people were walking around. The transmitter sent a wireless signal whose received signal strength was measured by the receiver. The estimate of the number of people present is based on these received signal power measurements.

Mostafi’s group has previously demonstrated the use of WiFi for crowd counting, but this is the first time through-wall counting has been demonstrated. “Enabling through-wall crowd counting is considerably more challenging due to the high level of attenuation by the walls,” said Mostofi.