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Hao Min, Auto-ID Lab at Fudan
High Sensitivity RFID for Tracking Assets
4th October, 2016
© GS1 2016
Outline
• Existing passive EPC Gen2 RFID
• Long read range requirement
• Current solutions & proposed solution
• Design and principle of the active tag
• Experimental results
• Summary & comparison
2
© GS1 2016
EPC Gen2 Passive RFID
• Passive tags
- Energy from readers
- Without battery
• Typical read range
around 10m
EPC Gen2 Reader
Envelop Demodulator
Load Modulator
Passive Tag
Energy & Data
Backscattered
RF Energy
Power Management
R=>T link limited by tag sensitivity
T=>R link limited by reader sensitivity
© GS1 2016
Performance of passive RFID
Reader
- +30dBm EIRP output
power
- −80dBm sensitivity
Tag
- Impinj Monza R6 Tag
- Sen.= -22.1dBm
4
Reader Impinj Speedway Reader
Air InterfaceProtocol
EPCglobal UHF Class 1 Gen 2ISO 18000-6C
OperatingFrequencies
865-956MHz
RF Power +30 dBm
Sensitivity -80 dBm
© GS1 2016
RFID for Asset Management
© GS1 2016
Motivations & Objectives
• Enhanced functions needed for wider
adoption
- Longer range: 100m
- Sensor capability
• Unified reader
- Current commercial readers can be used for
the enhanced functionalities
- Unified data management software can be
used
© GS1 2016
Current Solutions
• Current long range Manchester
BAP
- Special reader
- Not compliant with EPC Gen2
• Current active tag
- ISM band radio
• ZigBee
• High power due to beacon
• Complex protocol
• High cost
- Different data infrastructure
Implantables
10k 100k 1M 10M1k
1cm
Gen2 RFID1m
10m
100m Zig-Bee Blue-
tooth
Objective
Bit Rate (bps)
Op
era
tin
g R
ang
e
© GS1 2016
Solutions
• Intelleflex
- ISO-18000-6 BAP
- Backscatter
- Tag Sen. -40dBm
- Reader Sen. -120dBm
NO. 1 NO. 2 NO. 3
Reader Increase output power;Modifysensitivity;
Modifysensitivity;
Unchanged
Tag Unchanged BAP tags; Active tag with excellent sensitivity;Transmit power when necessary.
Parameters Pr_tx= 56dBm(NOT allowed);Pr_sen= -120dBm; (Difficult);
Pr_sen= -120dBm(Difficult);Pt_sen= -42dBm(Battery needed);
Pt_sen= -42dBm(Battery needed);Pt_tx= -8dBm(Battery needed);
Comments Bad idea Good idea Good idea
Pros and Cons
- Difficult;High cost with modified reader design;BAP Tag;
Reader unchanged;Low cost;Battery life(4-5 years is possible).
© GS1 2016
Bottlenecks: RF Power
• Backscatter modulation
• Maximum read range
- Limited by reader sensitivity
- Increase tag output power
• Self-jammer in reader
- Limited reader sensitivity
- -80dBm
Tag Chip
ZANT
ZC1VT
IT
ZC2
Antenna
RFID Reader
CW Query CW
Reply
RCS1
RCS2
Power Amplifier
Up-Mixer
Reader Commands
VIF
Down-Mixer
Tag
Backscattered
TX-RX Leakage30−25=5dBm
VBB
DCOC LPF
Circulator
Pout,r
Psen,r
reade
1
42 2 R
max R
r
T4π
PR K
SENG G
© GS1 2016
Proposed Solution
• Active transmitting
- Increased tag output
power
• Carrier recovery
- Track reader carrier
- Hold for tag TX
• Reader sees the
same signal as
from passive tags
Battery
Active Tag
OOK TX with CRC
EPC Gen2 Reader
Envelop Demodulator
Load Modulator
Passive Tag
Energy & Data
Backscattered
RF Energy
Power Management
Envelop Demodulator
EPC Gen2 Reader
Data
R=>T link limited by tag sensitivity
T=>R link limited by reader sensitivity
(a) Traditional EPC Gen2 passive RFID system
(b) Proposed EPC Gen2 active RFID system
© GS1 2016
Active Tag Using CRC
• Increased tag sensitivity
• Increased tag output power
- Reader unchanged
• CRC (Carrier Recovery Circuit)
- Tracking in the CW
- Holding for the TXEnvelop
Demodulator
OOK Modulator
EPC C1G2 Baseband
& Control Unit
Carrier Recovery Circuit
DEMOD
MOD
LO
HOLD
TDD
TDDEN
© GS1 2016
Gen2 compatible Active Tag Prototype
• Envelop demodulator
- Reader command
• OOT transmitter
- Tag reply
• Carrier Recovery Circuit
- Carrier fLO
• EPC Gen2 baseband
Envelop Demodulator
OOK Trasmitter
EPC Gen2 Baseband
Carrier Recovery Circuit (CRC)
DEMOD
MOD
fLO
HOLD
EN
MOD
CRC Control Unit
DEMOD
PMU
RFI
RFO
CW CWQuery
RN16 PC/XPC+EPC+CRC
CWAckReader
Tag
CW Select
EN
HOLD
T0 T1 T7
Recovering Maintained
© GS1 2016
Functionality Test
• Link timing
• Carrier recovery
Reader
Tag
EN
HOLD
Quary
RN16
PC/XPC+EPC+CRC
1.38ms
Antenna
Down-mixer & LO
Envelop Demodulator/OOK Transmitter/Tag Baseband FED PLL &
Control Unit
Power Splitter
Comparator
CRC
CW CWQuery
RN16 PC/XPC+EPC+CRC
CWAckReader
Tag
CW Select
EN
HOLD
T0 T1 T7
Recovering Maintained
© GS1 2016
Communication Test
• Reader software
- Read rate
- Power parameters
• Attenuator
- Free-space path loss
- 0~91dB with 1dB stepRead Results EPC Gen2 Reader
Active TagAttenuator
© GS1 2016
Power & Read Range
• Reader
- Output power: 30dBm
- Input power: −74dBm
• Tag
- Input: −39.5dBm
- Output: −4.5dBm
• Maximum read range
- 154.6m• Antenna gain: 6dBi & 0dBi
• Maximum PL: 69.5dB-80
-75
-70
-65
-60
-55
-50
-45
-40
1
2
4
8
16
32
64
128
35 40 45 50 55 60 65 70
Rea
de
r R
SIm
x [
dB
m]
Rea
d R
an
ge
[m
]Free-space path loss [dB]
Read Range
Reader RSImax
© GS1 2016
Outdoor Test
• Antenna gain
- Greader=6dBi
- Gtag=2dBi
• Read range
- 90~105m
• Channel
97m
Read Results
105m 90m
© GS1 2016
Hao Min
Director
+86 21 51355220
www.autoidlabs.org
+86 21 51355219
+86 13801912787
Auto-ID Lab at Fudan, 825 Zhangheng Road, Shanghai China