Enhancing localization accuracy with multi-antenna UHF RFID fingerprinting

Accurate indoor positioning systems are still expensive in terms of hardware price or computing complexity. Cost reduction of wireless devices, reuse of already deployed infrastructures besides the non-intrusive features (compared to vision-based systems) of radiofrequency (RF) solutions, make these systems good candidates for cost effective indoor positioning systems. Here, the use of multi-antenna devices could help to improve location accuracy and to reduce the infrastructure costs. This paper presents a signal strength-based localization system using active UHF RFID. Different indoor positioning techniques are defined and analyzed, particularizing them for the multi-antenna case. The system performance is assessed for these methods and comparing one and two-antenna readers based on the field trial measurements. Finally, a trade-off of the number of tags and number of antennas is carried out in order to evaluate the capability of the presented system to reduce fixed infrastructure costs.