Device-Free 3-Dimensional User Recognition utilizing passive RFID walls

User localization information is an important data source for ubiquitous assistance in smart environments and other location aware systems. It is a major data source for superimposed intention recognition systems. In typical smart environment scenarios, like ambient assisted living, there is a need for non-invasive, wireless, privacy preserving technologies. Device-free localization approaches (DFL) provide these advantages with no need for user-attached hardware. A common problem of DFL technologies is the distinction and identification of users which is important for multi-user localization and tracking. Expanding the existing approaches with the 3rd dimension it becomes possible to estimate user heights and body shapes depending on the systems resolution. For that purpose we place pRFID transponders at the room’s walls giving us the possibility to generate a 3 dimensional wireless communication grid within the localization area. A person moving within this area is typically affecting the RFID communication giving us the possibility to use RSS based algorithms. In this work we show the basic approaches and define system and model related adaptations. We conduct first experiments in an indoor room DFL scenario for proof of concept and validation. We show that it is possible to recognize the height of a user with reasonable precision for future estimation approaches. KeywordsDFL, RFID, Indoor Navigation, Smart Environments, Pervasive Computing, Wireless