RFID coordinate registration for agricultural process sensing

A major challenge with RFID tags is to obtain their coordinates in the cost effective manner that makes them so attractive in the first place. For example, adapting well known radar methods for coordinate registration will increase the RFID system complexity and thus cost and maintenance considerably. In this paper we develop a system to determine the location of RFID tags using RSS (Received Signal Strength) measurements between tags and the reader to estimate their position. Tag positioning with this system can be made with a single portable reader without the need for triangulation. The WSN (Wireless Sensor Network) is treated as an optimisation problem where relative positioning is found using a MCMC (Markov Chain Monte Carlo) technique. Simulations show that using this process it is possible to improve estimates for tag location at long ranges without major modification to currently available systems.