Scientists have developed a technique to gauge human density using Wi-Fi. According to the researchers at the University of California, Santa Barbara (UCSB), Wi-Fi can also be used to determine the number of people in a given space, even if they are not carrying a Wi-Fi enabled device.

The study was led by Yasamin Mostofi, a professor of electrical and computer engineering at UC Santa Barbara. The research team put two Wi-Fi cards at opposite ends of a target area, a roughly 70-square-meter space.

They found that by using only the received power measurements of the link between the two cards, the number of people walking in that area can be estimated.

The human body crossing the line of the signal can cause the signal to scatter. This phenomena is called, ‘multi-path fading’. The individuals that break a direct link between two Wi-Fi transmissions enable the program to register their presence.

The researchers said, “By developing a probabilistic mathematical framework based on these two key phenomena, the researchers then proposed a way of estimating the number of people walking in the space”.

The findings have the potential for many diverse applications. For instance, this method can be used to adjust air conditioning and heating, counting the number of shoppers in stores and even in search and rescue situations.

The Mostofi’s research group’s discoveries are scheduled for publication in the Institute of Electrical and Electronics Engineers Journal.