Passive RFID Positioning Technology and Applications Dr. Zhu Hailong Senior Manager, R&D, LSCM
outline 1 Introduction 2 AOA-based RFID RTLS 3 RSSI-based RFID RTLS 4 PDOA-based RFID RTLS
1 Introduction 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
Introduction 1 Real Time Locating System (RTLS) is a wireless system with the ability to locate the position of an item or a person anywhere in a defined space at a point in time that is, or is close to, real time. 2 Global Positioning System (GPS) has been widely used for outdoor application in the world. Other technologies focus on Last-1 meter and indoor locating technology. 3 RFID (Radio Frequency Identification /UWB (Ultra Wide Band) / CSS (Chirp Spread Spectrum) and other indoor positioning technologies. 4 Many different RFID-based localization systems have been developed and applied to lots of areas in recent years, like emergency rescuing, patient tracking, asset or livestock tracking, and many other areas.
Typical Application of RTLS using UHF RFID livestock tracking asset tracking in logistics emergency rescuing, Intelligent patient management retail or supermarket Library
Overview of indoor positioning technologies 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
Nanotron-based on Chirp Spread Spectrum 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
Short-duration (sub-nanosecond) Robustness to multipath fading. Narrowband IR-UWB Good range resolution 9 R res : Range resolution c : Speed of light ε r : Media dielectric constant B: Bandwidth 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
Decawave-based on Ultra Wide Band 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
Indoor Locating technology using UHF RFID RFID-Based locating technology Non-Range based Reader reference tag reference RSSI Range based AOA PDOA TDOA TD-PDOA FD-PDOA SD-PDOA
2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved. Function of the system Zone locating for RFID tag in reading range Solution 1 : base on AOA signal of high performance RFID reader -> x-array. Solution 2: base on RSSI signal of high performance RFID reader. Solution 3:base on PDOA signal of high performance RFID reader.
2 AOA-based RFID RTLS 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved. x-array based on AOA technology For large-scale item-level applications in retail, healthcare and manufacturing. Provided by 2D array with 52 dual polarized antenna beams. Monitor up to 1,500 sq.ft (139m 2 ) with 5ft (1.5m) or better spatial resolution.
3 RSSI-based RFID RTLS 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved. Requirement of RSSI- based RFID RTLS Two antennas + one reader solution for RFID RSSI positioning. Accurate RSSI value for reading range calculation (0.5m accuracy). Interference and orientation of RFID tag will cause effect to positioning result. Adjustment and compensation is needed for system deployment.
1 Stable and accurate signal input from radio frequency front end. 2 Suppress effect from antenna polarization and interference (including reader and tag antenna). Suppress un-linearity of none idea cable and circuit trace for different frequency. Especially for frequency hopping mode. 3 Stable and accurate signal input for I/Q processing
RSSI positioning methodology
4 PDOA-based RFID RTLS 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.
FD-PDOA based RFID RTSL Φ1=2*d*2πf1/c=m*2π+ΔΦ1 Φ2=2*d*2πf2/c=n*2π+ΔΦ2 ΔΦ=ΔΦ1-ΔΦ2=2*d*2π/c*(f1-f2) d=c*δφ/4π(f1-f2) Dmax=c/2(f1-f2)
Triangulation algorithm for FD-PDOA Tag(x,y) d1 d2 RX1(-2,0) RX2(2,0)
Phase Difference of Arrival Distance Estimation
Phase Based Spatial Identification of PDOA system
Simulation Model of PDOA-based RTLS
Simulation Results of PDOA-based RTLS Tag1: real location (3, 6) Detected location: (3.1276, 6.062) (7.938, +26.3 degree) RX_A_ref Tag2: real location (-2.5, 6.5) Detected location: (-2.6624, 6.4975) (6.5, -21.5 degree) RX_A_ref Simulation accuracy is less than 20cm
2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved. PDOA reader receiver configuration Antenna switch Carrier cancellation Waveform sampler & preamble detector. Down conversion to zero IF Dual (I/Q) base band Two 14/12 bits ADC (Impinj used 12 bits version, -80 dbm sensitivity), sampled clocked at 20.48MHz.
2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved. Basic FDOA system block diagram Antenna 1 Antenna 2 Antenna 3 Antenna 4 RF Switche s Leakage Carrier Cancellation RF & Analog Front End MCU FPGA LCC Board Location reader Board Digital Base Band Board Leakage-carriercancellation board Location reader front-end Board
Thank you 2015 Hong Kong R&D Centre for Logistics and Supply Chain Management Enabling Technologies. All rights reserved.