Indoor localisation for complex building designs using passive RFID technology

Amongst various application usages of Radio Frequency Identification (RFID) Technology, Indoor localization or positioning has gained much importance and value over the past few years. Different algorithms and hardware have been developed with active research still in place. Research towards localization of objects and personnel specifically using passive RFID technology has immensely reduced the overall solution cost, while effectively increasing positioning accuracy. In this paper, we present a passive RFID-based indoor localization algorithm for the Buildings and Constructions Industry. In complex building designs, such as multi-storey car parks or high-rise hospitals, it is often required to locate a particular car or medical personnel at least at a room level accuracy in case of emergencies. In the methodology presented, passive RFID tags with unknown locations are tracked and identified using a number of similar tags with known positions. This approach offers the advantage to have less number of expensive RFID readers to locate unknown tags. Instead, low cost passive RFID tags collaborate together to find the unknown tags' locations. The distance and positions of the known tags along with mathematical techniques and computations form the basis of our algorithm to compute the final position of unknown tags. The experimental results are acquired by considering a simulated implementation in a 10m×10m room using two UHF RFID readers. A number of simulation results show an average linear error in positioning of 1.32m from reader 1 and that of 3.14m from reader 2.