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Tagoram: Real-Time Tracking of Mobile
RFID Tags to High-Precision Accuracy
Using COTS Devices
Xiang-Yang Li
Lei Yang, Yekui Chen Chaowei Xiao, Mo Li, Yunhao Liu
Tagoram: Real-Time Tracking of Mobile
RFID Tags to High-Precision Accuracy
Using COTS Devices
Xiang-Yang Li
Lei Yang, Yekui Chen Chaowei Xiao, Mo Li, Yunhao Liu
Known Track 04.
Outline
State-of-the-art 02.
Technique Overview 03.
Implementation & Evaluation 06.
Unknown Track 05.
Motivation 01.
Pilot Study 07.
Other Research 08.
Motivation
Portal
Real-time Tracking
Access control
Livestock
Payment devices
Logistics
Passport Automobile immobilizers
RFID Technology
RFIDs
5-cent stickers to tag any and every object
Reader’s range is ~15m
billions of RFIDs were deployed for inventory management and object tracking
Battery-free RF stickers with unique IDs Imagine you can localize RFIDs to within 10 to 15 cm!
No more customer checkout lines
If we can locate RFID to within 10 to 15cm
RFID Proximity as Indicator!
RFIDs on
Basket,
goods
Automatic production
Imagine you can localize RFIDs to within 0.1cm to 1 cm!
Goal-line technology
Imagine you can localize RFIDs to within 0.1cm to 1 cm!
Human-computer interface
Imagine you can localize RFIDs to within 0.1cm to 1 cm!
Baggage sortation in airport
Imagine you can localize RFIDs to within 0.1cm to 1 cm!
Demonstration http://young.tagsys.org/tracking/tagoram/youtube
High-Precision RFID Tracking Using COTS Devices
30cm 40cm
Drawing in the Air
TrackPoint Deployed at Airports
Reader
Industrial
computer
State-of-the-art
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm
LANDMARC Lionel M. Ni
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm
LANDMARC Lionel M. Ni
[3] P.Nikitin, etal
Phase based spatial identification of uhf
rfid tags.
IEEE RFID 2010.
680mm
[2] C.Hekimian-Williams, elta
Accurate localization of rfid tags using
phase difference.
IEEE RFID 2010.
280mm
Diff based C. H.Williams
Spatial based P. Nikitin
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm [3] P.Nikitin, etal
Phase based spatial identification of uhf
rfid tags.
IEEE RFID 2010.
680mm
[2] C.Hekimian-Williams, elta
Accurate localization of rfid tags using
phase difference.
IEEE RFID 2010.
280mm
Diff based C. H.Williams
Spatial based P. Nikitin
[4] Salah Azzouzi, etal
New measurement results for the
localization of uhf RFID transponders
using an angle of arrival (aoa) approach
IEEE RFID 2011.
300mm
210mm
[5] R. Miesen etal.
Holographic localization of passive uhf
rfid transponders.
IEEE RFID 2011.
AOA based S. Azzouzi
Holographic R. Miesen
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm
[4] Salah Azzouzi, etal
New measurement results for the
localization of uhf RFID transponders
using an angle of arrival (aoa) approach
IEEE RFID 2011.
300mm
210mm
[5] R. Miesen etal.
Holographic localization of passive uhf
rfid transponders.
IEEE RFID 2011.
AOA based S. Azzouzi
Holographic R. Miesen
[6] Jue Wang, etal
Dude, where's my card?: RFID positioning
that works with multipath and non-line of
sight
ACM SIGCOMM 2013
110mm
12.8mm
[7] Jue Wang, etal
RF-compass: robot object manipulation
using RFIDs
ACM MobiCom 2013
PinIt Jue Wang
RF-Compass Jue Wang
680mm
[2] C.Hekimian-Williams, elta
Accurate localization of rfid tags using
phase difference.
IEEE RFID 2010.
280mm
[3] P.Nikitin, etal
Phase based spatial identification of uhf
rfid tags.
IEEE RFID 2010.
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm
[4] Salah Azzouzi, etal
New measurement results for the
localization of uhf RFID transponders
using an angle of arrival (aoa) approach
IEEE RFID 2011.
300mm
210mm
[5] R. Miesen etal.
Holographic localization of passive uhf
rfid transponders.
IEEE RFID 2011.
[6] Jue Wang, etal
Dude, where's my card?: RFID positioning
that works with multipath and non-line of
sight
ACM SIGCOMM 2013
110mm
27.6mm
[7] Jue Wang, etal
RF-compass: robot object manipulation
using RFIDs
ACM MobiCom 2013
[8] Tianci Liu, etal,
Anchor-free Backscatter Positioning for
RFID Tags with High Accuracy
IEEE INFOCOM 2014
128mm
[9] Jue Wang, etal,
RF-Idaw: Virtual Touch Screen in the Air
Using RF Signals
IEEE INFOCOM 2014
37mm
BackPos Tianci Liu
RF-IDRaw Jue Wang
[3] P.Nikitin, etal
Phase based spatial identification of uhf
rfid tags.
IEEE RFID 2010.
680mm
[2] C.Hekimian-Williams, elta
Accurate localization of rfid tags using
phase difference.
IEEE RFID 2010.
280mm
PinIt Jue Wang
RF-Compass Jue Wang
RFID Tracking & Localization State-of-the-art
2004 2014 2013 2011 2010
[1] Lionel M. Ni, Yunhao Liu, etal
LANDMARC: Indoor Location Sensing
Using Active RFID
Wireless Networks
1120mm
[4] Salah Azzouzi, etal
New measurement results for the
localization of uhf RFID transponders
using an angle of arrival (aoa) approach
IEEE RFID 2011.
300mm
210mm
[5] R. Miesen etal.
Holographic localization of passive uhf
rfid transponders.
IEEE RFID 2011.
[6] Jue Wang, etal
Dude, where's my card?: RFID positioning
that works with multipath and non-line of
sight
ACM SIGCOMM 2013
110mm
27.6mm
[7] Jue Wang, etal
RF-compass: robot object manipulation
using RFIDs
ACM MobiCom 2013
[8] Tianci Liu, etal,
Anchor-free Backscatter Positioning for
RFID Tags with High Accuracy
IEEE INFOCOM 2014
128mm
[9] Jue Wang, etal,
RF-Idaw: Virtual Touch Screen in the Air
Using RF Signals
ACM SigComm 2014
37mm
BackPos Tianci Liu
RF-IDRaw Jue Wang
WE ARE HERE
7mm
[3] P.Nikitin, etal
Phase based spatial identification of uhf
rfid tags.
IEEE RFID 2010.
680mm
[2] C.Hekimian-Williams, elta
Accurate localization of rfid tags using
phase difference.
IEEE RFID 2010.
280mm
State-of-the-art Techniques
RSS based Methods 1
RSS is not a reliable location indicator especially for UHF tags
RSS Orientation VS
Phase based Methods 2
PinIt (SIGCOMM 2013) RF-Compass (MobiCom 2013)
Needs to deploy dense reference tags
State-of-the-art Techniques
Summary of Challenges
Need mm-level localization accuracy achieved • especially for mobile tags.
Small overhead, COTS devices • infeasible for using many references for a tracking
system spanning a long pipeline.
Fast-changing environment • multipath reflection of RF signals • varied orientation of tags • Doppler effect
How Tagoram works? Overview the basic idea
Backscatter Communication
COTS RFID Reader
0.0015 radians (4096 bits)
Problem definition
Surveillance region
Reader antenna
Bird’s Eye View of Tagoram
Surveillance region
Reader antenna
Tagoram
Controllable Case Case 1.
Uncontrollable Case Case 2.
Movement with
Known Track Controllable case
Trajectory
Track
Track vs. Trajectory
A function of time–space relationships
A function of geometric relationships
VS
Virtual Antenna Array
Conveyor
Inverse Synthetic Aperture Radar
Initial
position
RF Hologram
How to define the likelihood?
The key is
RF Hologram
Naïve Hologram
Augmented Hologram
Differential Augmented Hologram
Thermal noise
Device diversity
Naïve Hologram
The real signal
The theoretical signal
A virtual interfered signal
Naïve Hologram
Virtual interfered signal
Sum of all signals
Naïve Hologram
Real axis
Imaginary axis
Naïve Hologram
Real axis
Imaginary axis
Naïve Hologram
High PSNR
Influence from Thermal Noise
Experiment Observations
CDF Modeling
How to deal with thermal noise?
Augmented Hologram
Augmented Hologram
A probabilistic weight
Augmented Hologram
Ground truth Result
Shift
scattered
What is missing again? Tags are different!
Tag diversity
Influence from Tag Diversity
Experiment
Observations
Random test
Modeling
At same position
Tag diversity
Pass KS-test to be verified over a uniform distribution with 0.5 significant level.
How to eliminate tag diversity?
Differential Augmented Hologram
Differential Augmented Hologram
Using difference of difference of phase values
Differential Augmented Hologram
Result
Ground truth
How to achieve the real-time?
Incremental computations
Saving Computations in Spatial Domain
Observation: The computations on blue pixel (low level PSNR) are totally wasted
Movement with
Unknown Track Uncontrollable case
Overview
Estimating Speeds,
Fitting tag’s trajectory
1
Selecting the optimal trajectory 2
Observations
Fitting tag’s trajectory
More complicate cases are discussed in our paper.
Fitting Tag’s Trajectory
Fitting the speed using NLS
Fitting Tag’s Trajectory
Trajectory
Speed Chain
Selecting the Optimal Trajectory
Unknown!
Implementation & Evaluation Purely based on COTS devices
Hardware & Software Introduction
ImpinJ R420 reader.
4 directional antennas
Reader Tag
Alien 2 × 2 Inlay
Alien Squiggle Inlay
Software
EPCglobal LLRP
Java
Linear Track
• A toy train on which a tag is attached.
• The system triggers the camera to take a snapshot on the train when firstly read.
• A camera is installed above the track to capture the ground truth.
Tracking Accuracy in Linear Track
DAH
Impacts of frequency and orientation
Both frequency and orientation take limited impacts on tracking accuracy.
Impact of frequency Impact of orientation
Real-time evaluation
Read-time Accuracy vs. Real-time
100 reads (~ 3.3s)
Impact of distance
No obvious pattern between distance and accuracy
Controllable Case with Nonlinear Track
• The track’s internal diameter is 540mm
Nonlinear track
DAH
Under Uncontrollable Case
A median of 12.3cm accuracy with a standard deviation of 5cm ---- better method proposed later, with about 1cm accuracy
Pilot Study In two airports
TagAssist: RFID assisted baggage sortation
Automatic Track & Check Service Collaborated with Hainan Airline
Where baggage lost?
Main factors to baggage loss
Relevant to baggage tracking
Current workflow – Manual sortation
Sortation carousel Sorting baggage
It is error-prone step to find the baggage from the carousel in manual sortation.
How to assist sorter quickly find and sort baggage?
Step 1: Upgrade Printer
We upgraded the tag printer by embedding a module of RFID reader in printer and an inlay inside each baggage tag.
Step 2: TrackPoint
Reader
Industrial
computer
Step 3: Visualization
Pilot site
Beijing Capital International Airport
Sanya Phoenix International Airport
Setup
• Each airport contains 5 TrackPoints, 4 visualization screens, and 22 RFID Printers.
• The two-year pilot study totally spent more than $600,000
Setup
•Consumed 110,000 RFID tags.
• Involved 53 destination airports, 93 air lines, and 1,094 flights.
Tracking Accuracy
Tagoram achieves a median accuracy of 6.35cm in practice.
Efficiency Improvement
Sorting carousel
Tagoram decreases the mean distance by 30%.
Tolerance to multipath
Tagoram has strong tolerance to multipath effect
Top four multipath cases Tracking accuracies
Other Research
88
OceanSense GreenOrbs CitySee
Networking observations
ZIMO:
Coexistence
Capacity: Large
scale
CitySee System (2011--)
Sensor nodes, mesh routers
90
Cyber Physical Systems
Cognitive Radio Networks
92
Capacity of Large Scale Networks
Our iGaze Glasses
Acknowledgments
PhD Students (alumni 10)
96
UNCC GSU Google W. Oregon
Tsinghua Motorola financial
financial
UT Dallas Toledo
Current PhD Students
97
MS Students
98
Students
99
100
100
Demo Video
Airport Video
Influences from other factors
1
2 Why tolerate NLOS?
Why tolerate Doppler effect?