VIRE: Virtual Reference Elimination for Active RFID-based Localization

RFID technologies are gaining much attention as they are attractive solutions to many applications. Localization based on active RFID technologies provides a much needed added-value to further expand the application domain. LANDMARC was the first attempt using active RFID for indoor location sensing with satisfactory results. However, the LANDMARC approach suffers from two drawbacks. First, it does not work well in a closed area with severe radio signal multi-path effects. Second, to further improve the localization accuracy, more reference tags are required which is costly and may trigger the RF interference phenomenon. The proposed VIRE approach can overcome the above drawbacks without any additional cost. Based on the concept of virtual reference tags, a proximity map is maintained by each reader. An elimination algorithm is used to eliminate those unlikely locations to reduce the estimation error. Our experimental results show that the new method consistently enhances the precision of indoor localization from 17 to 73 percent over the LANDMARC approach at different tag locations in different environments.