Researchers at UC Santa Barbara have discovered that wireless signals can help count the number of people in an area. The researchers were able to accomplish this by placing two WiFi cards at opposite ends of a target area – using changes in the wireless signals to determine the amount of people.
The way it works is based on the accuracy of the point-to-point wireless signal, with at large part based on the changes of the received signal. In short, the presence of the human body reduces the effect of the wireless signal path – Line Of Sight (LOS) and scatters the signal – causing a phenomenon called multi-path fading. The researchers then developed a mathematical equation based on both of those observations and were able to very closely estimate the number of people in the test area.
Something like this – that could accurately estimate the number of people in an area, could have many practical uses. The researchers plan on publishing their findings in the Institute of Electrical and Electronics Engineers Journal.