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

hmin@fudan.edu.cn

+86 21 51355219

+86 13801912787

Auto-ID Lab at Fudan, 825 Zhangheng Road, Shanghai China