[goochphd]

Wi-Fi or another radar-type device (like the one we developed) is the way to go. That got around people not wanting, or simply forgetting, to wear a device, but it did have its own technical challenges.

A sensor fusion approach is a great option, and wearables + some radar-based system seems like a best of all worlds solution, if people will use the wearables. Another big bonus you get from wearables is vitals detection, although I implemented a couple over-the-air vitals detection algorithms with our radar device that were sometimes very reliable.