Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
The reason the FCC is only allowing the sale of state approved routers in the US?
Sure as well is awkward for a mobile phone.
Maybe short distance low power milimeterwave can work. It won’t penetrate through walls.