Figure 2.1 Key Operational Parameters and Design Trade-off

Range Bandwidth

Data Rate

SemiconductorTechnology

BER

SNR

DigitalModulation

RX Sensitivity NF

NoiseTX Power &Frequency

Figure 2.2 Worldwide regulatory allowances for UHF RFID operation

Similar Range to FCC

Similar Range to EuropeLowest Performance Regions

Rest of WorldAllocations

Pending

Start End Watts SharingFCC CFR 47 Part 15.247902-928 MHz, 4W, EIRP

EN 302-208865.6 – 867.6 MHz

2W ERP

Figure 2.3 Radiated power relative to EIRP and ERP

Theoretical Half-Wave Dipole

Theoretical Isotropic Radiator

DipoleOrientation

Figure 2.4 Effect of sensitivity on range

Pass

ive T

ag S

ensi

tivity

(mW

)

Operating Range (Meters)

EU: 869 MHzEU: 915 MHz

EU: 2.45 GHzEU: 13.56 MHz

50

0 1 2 3 4 50.01

0.1

1

10

100

1 103

1 104

1 105

1 106

Figure 2.5 Comparison of FCC and EU spectral masks

-20 dBc200 kHz

EN 302-208

-36 dBm

-30 dBc

0 dBc

200 kHz 200 kHz

fcarrierFcarrier -200 kHz Fcarrier +200 kHz

FCC 15.247500 kHz

Figure 2.6 EN 302-208 backscatter spectral mask

-15 dBm

-27 dBm

-36 dBm

-47 dBm

-54 dBm

fc + 300 kHz

fc + 600 kHz

870 MHz863 MHz

862 MHz

200 kHz

fc - 300 kHz

fc - 600 kHzfc

Figure 2.7 Signal quality for non-coherent ASK demodulation

0 2 4 6 8 10 12 14 161 10 8

1 10 7

1 10 6

1 10 5

1 10 4

1 10 3

0.01

0.1

1

Eb/No (dB)

Bit

Erro

r Pro

babi

lity

Figure 2.8 EU channelization under EN 302-208

865.0MHz

865.6MHz

867.6MHz

868.0MHz

100 mW

2W

500 mW

Figure 2.9 Interrogator Interference

CW InterfererCarrier

Backscatter Data IM Products

Figure 2.10 Signal from tag interference

a) Carrier modulated signal received without interferer

Demodulated data signal

Demodulated data signal

b) Interfering carrier in another channel

c) Corrupted data signal

Figure 2.12 Triangulation

Tag

RX1 RX2D

Tag

r

RegionOf

Uncertainty

rmsAngle error

Figure 2.13 Trilateration

(x1, y1)

(x3, y3)

d3

(x2, y2)

d2

d1

(x, y)

rmsrange error

RegionOf

Uncertainty

Figure 2.14 Multi-path interference

InterrogatorAntenna

Signal Null

Floor

Ceiling

SignalPeak

Obstruction

Tag

Figure 2.15 Impact from Materials

Reflections &Diffractions

Far FieldNear Field

Metals

Water

Detuning

Absorption

ReducedPerformance

Near FullPerformance

Poor or NoFunctionality

SomeDetuning

Figure 2.16 Packaged Active tag

Antenna

Battery

ASIC

Package

Figure 2.17 Tag technology categories

No Batteries Batteries

Em

itted

Ene

rgy

ActiveEnergy Harvesting(Semi Active)

Asset Tamperand Seal Tags

Solar Vibration

Far-Field –E

M R

adiationN

ear-Field –M

agnetic Coupling

Ref

lect

ed E

nerg

y

Semi-PassivePassive

Toll CollectionSupply Chain Labels

Figure 2.18 Performance and feature trade-off between

technology categoriesE

mitt

ed E

nerg

yR

efle

cted

Ene

rgy

Near-Field Far-Fielde.g. Wi-Fi (IEEE 802.11), UHF RFID (ISO18000-7), UWBe.g. RuBee (IEEE P1902.1), NFC (ISO 18092)

e.g. UHF RFID (ISO18000-6 & EPC)e.g. HF RFID (ISO 14443), LF RFID (ISO 14223-1)

Benefits• Robust link around

dense RF media• Magnetic field zone

control• Simple narrow-band

protocols maximize battery life

Deficiencies• Range limited to

antenna loop diameter• Multi-tag arbitration

speed limited by data rate

Benefits• Long range due to RF

propagation and higher transmit power

• High multi-tag arbitration rates possible due to larger bandwidth & data-rate

Deficiencies• Some bands require

spread spectrum and complex multiple access protocols; leads to higher power consumption

• Poor zone control

Benefits• Excellent zone

control• Robust near-field

energy harvesting for passive HF/LF RFID

• Robust media penetration

Deficiencies• Backscatter reader

sensitivity and loop antenna diameter limits practical range to within one meter

• Multi-tag arbitration limited by bandwidth and data rate

Benefits• Tens of meters of

range for passive tags• Longer range for

semi-passive tags; limited primarily by reader sensitivity

• High multi-tag arbitration rate

• Longer battery life

Deficiencies• Poor zone control• Poor RF media

penetration• Highly orientation

sensitivity due to weaker backscatter and multi-path propagation

Internal Power Source (e.g. Batteries)

External Power Source (e.g. R

F, Vibration, Light)

Figure 2.19 Application vs Technology

PersonnelTracking

HighLow

Long

Short

VehicleTracking

ShelvedItems

ConveyorBelts

Near-Field PassiveSemi-Active

Far-Field Passive& Semi-Passive

Throughput

Ran

ge

Far-Field Active

Table 2.1 Common RTLS Techniques for Indoor Positioning

Number of

Antennas

Location

Method

Positional

Information

1Proximity (Near-Field)

Proximity (Far-Field)

In or out of a magnetic field zone

Radial proximity to antenna

2 Triangulation A 2D position between antennas