Maybe a plug, maybe not. However, I strongly agree here (about the blanket on the couch). The perfect system should be able to do both 1) passive device-free

Maybe a plug, maybe not. However, I strongly agree here (about the blanket on the couch). The perfect system should be able to do both 1) passive device-free detection as well as 2) inferring information about your location of any personal device. To have a device in every room is no problem for me. As long as it is invisible and cheap.