A Portable Handheld Fine-Grained RFID Localization System with Complex-Controlled Polarization

Abstract

There is significant interest in fine-grained RFID localization systems. Existing systems for fine-grained RFID localization require infrastructure support, either in the form of extensive reference tags deployed in the environment or a deployed antenna infrastructure, such as antenna arrays, to localize RFID tags within its radio range. Yet, there remains a need for fine-grained RFID localization solutions that are in a compact, portable, mobile form, that can be held by users as they walk around areas to map them, such as in retail stores, warehouses, or manufacturing plants.

We present the design, implementation, and evaluation of EveryFind, a portable handheld system for fine-grained RFID localization. Our system introduces two key innovations that enable robust, accurate, and real-time localization of RFID tags in challenging environments. The first is complex-controlled polarization (CCP), a mechanism for localizing RFIDs at all orientations through software-controlled polarization of two linearly polarized antennas. The second is joint tag discovery and localization (JTDL), a method for simultaneously localizing and reading tags with zero-overhead regardless of the tag’s orientation. Building on these two techniques, we develop an end-to-end handheld system that addresses a number of practical challenges in selfinterference cancellation, efficient inventorying, and self-localization. Our evaluation over hundreds of RFID locations demonstrates that EveryFind achieves a median accuracy of few centimeters in each of the x/y/z dimensions and a 90𝑡𝑕 in practical indoor environments.