Efficient Data Transmission And Accurate Spatial Perception In RFID Systems

Radio Frequency IDentification (RFID) is an automatic identification technology that uses radio frequency radiation to identify labeled objects. As the key technology of Internet of things, RFID has been widely deployed in various applications, including supply chain management, warehouse inventory, electronic payment, access control, object monitoring, etc.To date, some problems in RFID systems have not been well investigated yet. For one, with the proliferation of RFID-enabled applications, the existing data transmis-sion ratio cannot meet the real-time application requirements of some large-scale R-FID systems. For another, with the development of the sensor technology and wireless communication, indoor spatial perception (including localization and direction find-ing) has attracted increasing attentions. Existing RFID work, however, mainly focuses on the research of localization algorithms; little work can identify a tagged object’s orientation.Considering above limitations, this paper concentrates on the research on efficient data transmission and accurate spatial perception in RFID systems. The former tar-gets at improving the efficiency of the information exchange between the reader and tags, speeding the management process of upper-layer applications. The latter aims to implement accurate direction finding as well as fine-grained localization, providing spatial-perception based applications with more compressive information. The contri-butions of this paper are summarized as follows:1) For the problem of efficient tag information collection, we follow a new design path that shortens the length of the polling vector to improve the query efficiency of the traditional polling. By using the hash indices and building the polling tree, we reduce the length of the polling vector from 96 bits to only 3 bits, greatly improving the polling efficiency and speeding the information collection.2) For the problem of improving the data transmission from the reader to tags, we take the first step to propose the RFID grouping problem. A filter-based serialized protocol and an ALOHA-based concurrent protocol are designed for improving the grouping performance, which pay the way for multicast transmissions, benefiting the aggregated queries in each group.3) For the problem of spatial perception, we design a Tag-Compass system by analyzing the physical-layer signal and exploring the polarization property of electro-magnetic wave.Tag-Compass cannot only pinpoint a tag’s location, but also accurately identify a tag’s orientation, ensuring reliable and comprehensive spatial perception.