Wireless Network Can Track Your In-House Movements

A Wi-Fi network can not only monitor your breathing, but detect your position and every movement within a room or building.

ZoomWhile testing some new equipment, Neal Patwari of the University of Utah in Salt Lake City discovered that breathing actually affects Wi-Fi signal strength. He came to this conclusion after noticing variations in wireless signal strength in certain parts of a room that were seemingly triggered by chest movements.

To prove his theory, Patwari placed 20 in-expensive wireless unitsaround an occupied bed which were arrayed so that they sent 2.4 GHz waves across the sheet, but with one-thousandth the power of a laptop's wireless card. The units themselves measured signal strength four times a second, thus the makeshift network was able to accurately estimate the person's breathing rate to within 0.4 breaths per minute after collecting 30 seconds worth of data.

Ultimately Patwari's test revealed that wireless signals bent around the subject's chest as it rose with each inhalation, causing them to travel a longer distance and decrease slightly in power. Naturally this discovery is being hailed as a new way to monitor a patient's breathing without having to cram tubes down into their lungs (which sucks and hurts). Some disagree however, as patient monitoring mostly depends on more input than just inhaling and exhaling.

But now there's fear that this new Wi-Fi network system could be placed around an entire room or building in order to track user movements within. This scenario is based on a prior study conducted by Patwari and a colleague which revealed that any movement can affect wireless signal strength, and that these changes in strength can be used to track users within a room even if they're sitting or lying down. Even more, the changes can be measured when the Wi-Fi signal passes through a wall and into another room.

That said, a similar Wi-Fi network could be tailored to spy on shoppers at the mall, on hotel guests, or restaurant patrons no matter what they're doing.