Researchers at the University of California, Santa Barbara, have shown that they can now count people through the walls using only the WiFi signals. This appears to be a worrying development for those who are troubled by the growth of the surveillance state. Interestingly, this development doesn’t require those who are carrying a wireless device. The method depends on RSSI, which stands for Received Signal Strength Indicator. It measures the power of the radio signal. It uses both WiFi emitter and a receiver outside of the room of interest. Researchers claim that they can count up to 20 people in a room. The WiFi equipment used is readily available in the market, and it needed minimal calibration before using it.
The presence and movement of people cause the RSSI to lower-drops, which is referred to as an event by the researchers. It is by analyzing the time between these events that the researchers can count the people who are present in the room. The method works accurately for up to two people. The approach was successfully tested 44 times in three different classrooms, a conference room and a hallway on the university campus. The tests involved counting people through wood, plaster and concrete walls.
There are many uses for this tech apart from surveillance. It can be used to facilitate teams to optimize the heating, cooling, and lighting of a building; event planners can use it to monitor crowd safety in any events venue. Unlike other methods, the approach can make use of equipment which is already present thanks to the excessive availability of WiFi. This development is based on the team’s previous work in counting people with WiFi and other radio signals. However, now they can do this through the walls. The team is also researching imaging through walls using WiFi carrying drone aircraft. The surveillance is undoubtedly an area of interest for them. IEEE publishes the research of the team with the title Crowd counting through walls using WiFi.