Relative Tag Locations Based on Time-Differences in Read Events for Practical Applications

Over the course of recent years, Radio Frequency Identification (RFID) technology has been applied in many different business domains to solve, for example, the problem of monitoring stock. However, keeping track of the exact (geo-) locations of items in stock is still an open problem. This is particularly problematic for logistics, retail as well as warehouses, where information about relative locations of items can drastically increase staff efficiency and business process efficacy. In this paper we set out to tackle the problem of determining relative distances between RFID tags based on time-differences in read events, without the introduction of additional hardware. To that end, we first present a novel approach, which leverages time-based distances for inferring relative RFID tag distances. We then qualitatively and quantitatively evaluate our proposed approach by inferring tag locations for different experimental setups, and comparing our results to ground truth data. Finally, we present and discuss the results of a case study, which emulates real-world conditions of retailers using RFID technology for stock taking. Our results show that time-differences in read events are suitable for calculating and approximating the relative position of RFID tags in several setups. We strongly believe that the results presented in this paper represent a novel and important step towards new approaches, which leverage time-differences in read events for inferring relative tag distances.