ECE professor Yasamin Mostofi and researchers’ new method enables WiFi signals to use their natural body restlessness to count the number of people who are seated fixedly

Researchers in the laboratory of Yasamin Mostofi, a professor at the University of California, Santa Barbara, used WiFi signals for the first time to calculate a stationary seated crowd without relying on people carrying equipment. The technology can also be counted through walls, and only needs to use wireless transmitters and receivers outside the area of ​​interest where the crowd is located. It has a variety of applications, including smart energy management, crowd control during a pandemic, business planning, and security. 

Mostofi, professor of electrical and computer engineering at UCSB, said: "The method we propose can estimate the number of people seated in an area from the outside." Carry equipment and work through walls."

The proposed method and experimental results appeared at the recently held 19th ACM International Conference on Mobile Systems, Applications and Services (MobiSys). 

In the team's experiment, a WiFi transmitter and a WiFi receiver (both ready-made) are located in an area where many people sit down. The transmitter sends a wireless signal, and its received power is measured by the receiver. By using only such received signal power measurements, the receiver can estimate how many people are present-this estimate closely matches the actual number of people.  

This innovation builds on the previous work of Mostofi Labs, which has pioneered the use of daily radio frequency signals (such as WiFi) for sensing since 2009. For example, their 2018 paper "Counting People Who Use WiFi to Pass Through Walls" showed how WiFi counts the number of mobile people. However, people must move around to be counted.

"Due to the lack of major body movements, counting people who are sitting in a fixed position is a rather challenging problem," Mostofi said. The success of her laboratory in this work is attributed to the new method they developed.

"Although people in a crowd are static, that is, they do not have any major body movements other than breathing, they do not remain still for long periods of time and often perform small on-site natural body movements called fidgeting," Mosto Fei explained. "For example, they may adjust their seat position, cross their legs, check their phones, stretch their bodies or cough, etc."

The researchers proposed that the collective natural restlessness and in-situ movement of the seated crowd carry key information about crowd counting, and for the first time showed how to extract the total irritability and calculate the total number of people based on the crowd. In them.

The researchers then developed a new mathematical model that statistically describes the collective fidgeting behavior of stationary people (ie, CFP and CSP), and explicitly correlates them with the number of people seated.

UCSB current-"Don't fidget! WiFi will count you" (full text)

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