Ultrasound user-identification for wireless sensor networks.

Indoor localization and asset tracking is an area of research which is finding increasing application in monitoring the wellbeing of elderly subjects in hospital or residential care environments. Radio frequency (RF) based localization methods tend to show poor performance in indoor environments, due to multipath scatter, and simple room-level misassociations, resulting from the relative transparency of some walls to RF waves. Ultrasound (US) localization has shown excellent room-level accuracy, and as US will not easily penetrate walls, room-level misassociations do not often occur.