1

Kyung-Kuk LeeOrthotron Co., Ltd.

2

Standardization&

Market

3

802.15.4a – alt PHY for 802.15.4

Addresses the following

– Globally deployable– Compatible / interoperable with 802.15.4– Longer range– Higher reliability– Ranging/localization support– Lower latency & support for mobility– Low cost

4

Standardization & MarketStandardization & Market

StandardizationStandardization

IEEE 802.15.4a(Dual Baseline)

Mandatory: 2.4GHz CSS(Chirp Spread Spectrum)

Optional: Chaotic

Optional: Chirp

Mandatory: IR-UWB(Impulse Radio)

2.4GHz Chirp-Radio UWB-Radio

5

Standardization & MarketStandardization & Market

Chirp-Spread-Spectrum is innovative Wireless SensorNetwork technologies and solutions that can be usedin Data-Communication and Ranging Applications

Enabler of Next Generation Wireless-Sensor-Network

Active in IEEE Standardization

StandardizationStandardization

6

Standardization & MarketStandardization & Market

The market: Sensor Network, Mobile Phones,and Consumer Electronics

Draft standard of IEEE802.15.4a (Chirp-RadioTechnology) is passes letter ballot (2006.1.)

Chirp-Shift-Keying wireless technology deliver better:- Robustness for data Communication: High Jamming Margin- Extended range: up to 600~800 meters- Mobility: support 200 Miles/hour- Precision Ranging: < 1 meter (ToA)- Ultra Low power consumption – extended battery life time

MarketMarket

7

Standardization & MarketStandardization & Market

MarketMarket

8

Standardization & MarketStandardization & Market

IEEE802.15.4a is the next generation ofthe IEEE802.15.4 + ZigBee technology.

Value Proposition- Leadership of New Standard- Royalty from Standard Product and Proprietary Mode - Product Leadership: ZigBee + 15.4a Dual mode- Highly valuable Function: Ranging, Higher Data-rate

Ranging of Wireless Sensor Network- Very High Demand of Ranging Capability- RSSI / ToA / TDoA

MarketMarket

9

Standardization & MarketStandardization & Market

IEEE 802.15.4a TimelineIEEE 802.15.4a Timeline

5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3

Task Group Forme xCall for application created July 2003Selection criteria dx xCall for intent to propose xCall for proposal issued xChannel Models Release x x x x

Preliminary Proposals x xPresent final proposals x x

Baseline proposal selected x

Proposal draft completed x x x x x x1st letter ballot completed x

Resolution of comments completed x x xRe-circulation completed x

Resolve re-circulation comments x2nd re-circulation x

Resolve 2nd re-circulation comments. x

3rd re-circulation xResolve 3rd re-circulation comments. x

Sponsor ballot period xSponsor ballot comment resolution. x x x

Re-circulation completed x xRevCom Approval x

2004 2005 2006 2007

The B

allot

is pa

sses

10

Chirp-Spread-Spectrum(CSS)

Technology

11

ChirpChirp--SpreadSpread--Spectrum TechnologySpectrum TechnologyChirp SignalChirp Signal

0( ) Re exp[ ( ) ] [ ( ) ( )]2

BWchirp s chirp

chirp

s t j t t j u t u t TTωω θ

⎡ ⎤= + + × − −⎢ ⎥

⎢ ⎥⎣ ⎦ ω

SωBWω

t

t

( )chirps t

Linear Chirp: Rectangular Window

Linear Chirp: Raised-Cosine Window

0( ) Re exp[ ( ) ] ( )2

BWchirp s RC

chirp

s t j t t j p tTωω θ

⎡ ⎤= + + ×⎢ ⎥

⎢ ⎥⎣ ⎦

-200 -150 -100 -50 0 50 100 150 200

0

0.2

0.4

0.6

0.8

1

Correlation Property of Chirp Signal

Am

plitu

de

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

12

ChirpChirp--SpreadSpread--Spectrum TechnologySpectrum TechnologyChirp SignalChirp Signal

Down-Chirp SignalUp-Chirp Signal

t

( )chirps t

t

( )chirps t

ωSω

BWω

t

ωSω

BWω

t

13

ChirpChirp--SpreadSpread--Spectrum TechnologySpectrum TechnologyChirp vs ImpulseChirp vs Impulse

Chirp Signal

t

t

Chirp

Correlation

Impulse Radio

t

t

Time-Hopping

Correlation

14

ChirpChirp--SpreadSpread--Spectrum TechnologySpectrum TechnologyChirp vs ImpulseChirp vs Impulse

■ SimilaritiesSpread-Spectrum: BW >> Rb (De-spreading Gain)High Correlation Peak, Narrow Impulse/Cross-correlation width(Pulse-width of Impulse) = (Pulse-width of Cross-Correlation of Chirp) @ Same BWGreat Resolvability of Multi-path

■ DifferencesCross-correlation Property:

- Chirp: Inherently very low side-lobe of cross-correlation- Impulse: Need very long code-sequence to realize low side-lobe of cross-correlation

Signal Voltage for Signal Power: ex. TX 0.1mW ( P = V2/2R, R = 50 ohm )- Chirp: low peak voltage ------------------------------ 0.1V (Sinusoid)- Half-Sinusoid Impulse: higher peak voltage --- 1.0V (duty-cycle 1:100)

PAPR:- Chirp: PAPR = 3dB (Theoretical Minimum value) easily achievable Eb- Impulse: PAPR = 13dB (ex. Same condition as above)

very high PAPR need high-voltage / long pulse sequence for Eb

15

Modulation&

Coding

16

Modulation & Coding

ModulatedSignal

Binary Datafrom PPDU Binary

SymbolMapper

Bi-Ortho.SymbolMapper

QPSKMapper

DifferentialEncoder

QCSKModulator

Bit to Binary Symbol mapper:Group every 3-bits (or 6-bits) into a Symbol for 1Mbps (or 250Kbps)

Binary Symbol to Bi-Orthogonal Symbol mapper:Each 3-bits (or 6-bits) symbol is mapped to one of 4-chip (or 32-chip)Bi-Orthogonal Symbol Sequence for 1Mbps (or 250Kbps)

QPSK Mapper:Group every alternative 4-chips into I and Q for Group of 4 QPSK

Differential Encoder: QPSK D-QPSKSymbol-by-Symbol Differential Encoding between Group of 4 QPSK

QCSK Modulator:Phase Modulation of 4 sub-chirps with Group of 4 D-QPSK Symbols

17

Modulation & CodingConcept of SubConcept of Sub--ChirpsChirps

t

ω

t

Real Imaginary Envelope

Base-band WaveformC(t)

1.2µs 2.4µs 3.6µs 4.8µs

Freq. – Time Property (Base-band)

1.00.5

7MHz

0.96µs

( )10

14 , 4.8 sec/1.25( ) 10log / 3 13.5B MHz TSpreading Gain BT bits dB

µ≅ ≅

= =

18

Modulation & CodingSubSub--chirp: Formula, Combinationschirp: Formula, Combinations

( )

( ) ( ) ( )0

3

, , , , , , , ,

4 4 3 4 3 4,

,0 0

,, , , ( )

QCSK / BCSK:

( ) ,

exp2

1, , 4 ( ) ,

m mchirp

n

n k k m k m n k m n k m RC n

j j j jn k n

n

k

k mk

c e e e or e

s t s t n

c j t T t T p t T

m piconet

wher

QCSK c

e

π π π π

µω ξ

∞

=

∞

= =

− −

=

⎡ ⎤⎛ ⎞= + − − × −⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦= ⋅⋅⋅

= =

∑

∑∑

( ) ( )( )

( )

, ,

6 6

6

7 7 71 2 3

0.5 1 1

1.1875 10 sec, 6.0 10 sec

, 2 6.95 10 1 , 0.25

4.6875 10 sec, 3.125 10 sec, 1.

1, -1 ( )

5625 10 s

nn k m sub chirp m

sub chirp

BW sub BW

or BCSK

T k T nT

T T

T

τ

µ ω ω π α α

τ τ τ

− −

− − −

= + + − − −

= × = ×

= = × × × + =

= × = × = ×

( )

( )( )

( ) ( )( )

4

, ,

ec, 0sec2

1 1

1 2

1 1 11 1 cos - 2 1 2

k m k m

sub

subRC

sub

f

Tt

Tp t tT

τω π

αα

α π αα α

⎧⎪⎪⎪⎪⎪⎪⎨⎪⎪⎪ =⎪⎪ = ×⎪⎩

−≤

+

⎡ ⎤⎛ ⎞⎛ ⎞+ − −⎢ ⎥= + ⎜ ⎟⎜ ⎟⎜ ⎟⎜ ⎟+⎢ ⎥⎝ ⎠⎝ ⎠⎣ ⎦

( )( )1 2 2

0 2

sub sub

sub

T Tt

Tt

αα

⎧⎪⎪⎪⎪ < ≤⎨ +⎪⎪⎪ >⎪⎩

km 1 2 3 4

1 +1 +1 -1 -1

2 +1 -1 +1 -1

3 -1 -1 +1 +1

4 -1 +1 -1 +1

km

,Table 1. k mξ

,Table 2. [MHz]k mf

1 2 3 4

1 fC-3.15 fC+3.15 fC+3.15 fC-3.15

2 fC+3.15 fC-3.15 fC-3.15 fC+3.15

3 fC-3.15 fC+3.15 fC+3.15 fC-3.15

4 fC+3.15 fC-3.15 fC-3.15 fC+3.15

km

19

Modulation & CodingConcept of SubConcept of Sub--ChirpsChirps

SpectrumFreq. – Time (Base-band)

t

ω

t

ω

t

ω

t

ω

I

II

III

IV

fdiff.

-20 -10 fc 10 20 (MHz)

-50

-40

-30

-20

-10

0Fbw = 7.0 MHzrolloff = 0.25;Fdiff = 6.3 MHz;Tc = 4.8usec

fBW

Same Spectrum with IEEE802.11bSame Spectrum with IEEE802.11b

20

Modulation & CodingConcept of SubConcept of Sub--ChirpsChirps

Freq. – Time (Base-band)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1

0

1

Base-band Waveform

Real Imaginary Envelope

t

ω

t

ω

t

ω

t

ω

I

II

III

IV

21

Modulation & CodingBiBi--Orthogonal Mapping TableOrthogonal Mapping Table

H8 =

H64 =

0 1 2 3 4 5 6 7 63Decimal:

22

Modulation & CodingBlockBlock--diagram: diagram: 88--ary Differentially Biary Differentially Bi--OrthogonalOrthogonal

QuaternaryQuaternary--ChirpChirp--SpreadSpread--Spectrum (DBOSpectrum (DBO--QCSS) ModulatorQCSS) Modulator

Data-rate: 1Mbps

S/P3

1:23 4

S/P SymbolMapper P/S

1 Mapper

QPSK33 4

S/P SymbolMapper P/S

1

2

1

14z−2

CSK Gen.

I

Q

Binary Data

1

DBO-QCSK

23

Modulation & CodingDBODBO--MCSK DemodulatorMCSK Demodulator

Differential Detector

Differential Detector

A/D 1Nz−

Movingsum

SymbolDe-MapperS/P1 4 3

*

2Nz−

Movingsum

SymbolDe-MapperS/P1 4 3

*

SelectLargest Data

24

Data Frame:Payload bit-rate : 1Mbps (r=3/4) / 250Kbps (r=6/32)

Preamble DelimiterLength+ Rate

(8+4)bits

20Chirp 4Chirp 8Chirp

MPDU (32x8+2)bits

120usec 24usec 48usec

Modulation & CodingFrame StructureFrame Structure

ACK Frame:Payload bit-rate : 1Mbps(r=3/4) / 250Kbps (r=6/32)

Preamble DelimiterLength+ Rate

(8+4)bits

20Chirp 4Chirp 8Chirp

MPDU

120usec 24usec 48usec

25

Chirp-Spread-SpectrumPerformance

26

CSS PerformanceMultiple piconetMultiple piconet

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

-5000 0 50000

0.2

0.4

0.6

0.8

1

Correlation Power (For Preamble Detection)

Correlation Property between the piconetDoes not need Synchronization inter-piconet

t

ω

t

ω

t

ω

t

ω

I

II

III

IV

27

CSS PerformanceCSS Signals: 22MHz BWCSS Signals: 22MHz BW

■ 4 piconet CSK Signal: Identical Auto-correlation PropertySame Ranging Accuracy

-2 5 0 -2 0 0 -1 5 0 -1 0 0 -5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 00

0 . 2

0 . 4

0 . 6

0 . 8

1

-2 5 0 -2 0 0 -1 5 0 -1 0 0 -5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 00

0 . 2

0 . 4

0 . 6

0 . 8

1

-2 5 0 -2 0 0 -1 5 0 -1 0 0 -5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 00

0 . 2

0 . 4

0 . 6

0 . 8

1

-2 5 0 -2 0 0 -1 5 0 -1 0 0 -5 0 0 5 0 1 0 0 1 5 0 2 0 0 2 5 00

0 . 2

0 . 4

0 . 6

0 . 8

1

68nsec

28

CSS PerformanceMultiple piconetMultiple piconet

I

II

III

IV

t

ω Duration of 2 Symbols (12 usec)

0.3usec 2.1usecd11 d12

0.6usec 1.8usecd21 d22

0.9usec 1.5usecd31 d32

1.2usec 1.2usecd41 d42

ωt

t

t

ω

ω

4.8 usec

29

CSS PerformanceSignal Robustness: Signal Robustness: Coexistence

0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.910-4

10-3

10-2

10-1

100

DInt / DRef

PE

R

100

10-1

10-2

10-3

10-4

0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

Dint. / Dref.

PE

R

System performance with IEEE802.11b Interference

Same Tx PowerDBO-CSS Signal is insensitive for W-LAN Interference

Desired Transmitter

Receiver Under Test

Uncoordinated Piconets’Transmitters

Dint. Dref.

30

CSS Performance

■ Data-Rate: - 2 rates: 1Mbps / 250Kbps

■ RF Tx Power: - 3 classes: 0.1mW / 1.0mW / 10mW

■ Mobility Value:- Data: Link Margin >= 34.8dB @ 2.4GHz Band- Chirp is insensitive for Doppler Shift: very small Ranging error and BER degrade

-4

Chirp Index:

Doppler Shift:

Ex) 14 , 4.8 sec, 2.4 8.23 10

5

Ranging Error

: 8.20 /

:

f BW chirp

d c f

c f c chirp BW

BW chirp c

f T

f f v c T

T c f v f v T f

f MHz T f GHz d v

v

d

Km h d

µ

µ

µ

µ

• =

• = × = ×∆

• = ∆ × = × = × ×

= = = ⇒ ∆ = × ×

= ∆ =

∆

-4 33 10 50 10 36 1.00 14 [ ]cm× × × =

31

SD Memory (32mm X 24 mm)

Ex)• Battery Capacity: 3V x 30mAh (324Joule)• Dimension: 10 x 2.5 (Dia. x Ht. mm)

2.4 GHz

BasebandRFPattern Antenna

(24mm X 14mm)

Button CellButton CellBatteryBattery

CSS PerformanceSize & Form FactorSize & Form Factor

32

Ranging

33

Ranging

Applications of RangingApplications of Ranging

Radar and Sonar data processingGeophysical / Seismic ExplorationBiomedical engineeringgeological acoustic soundingultrasound-basednondestructive testing

Mechanism of EchoMechanism of EchoA known signal is launched into a scattering mediumThe form of delayed overlapping echos in noiseTo be processed to yield informationRanging of Device

34

Ranging

Detection / DeDetection / De--convolution Schemesconvolution SchemesRSSICorrelationInverse FilteringLeast-SquaresMaximum Likelihood MethodsSuper-Resolution Algorithm

Major Problem to be ResolveMajor Problem to be ResolveUnknown number of Multipath ComponentsClosely spaced, Overlapping, and Noisy Echos of a SignalNeed to Detect 1st Arrival Time from Overlapped Echo

35

Ranging: RSSIRSSI Method: Poor AccuracyRSSI Method: Poor Accuracy

RSSI VariationsChannel ModelsFading / ShadowingLOS / NLOS

36

CSS Ranging: CorrelationCorrelation Method: Moderate AccuracyCorrelation Method: Moderate Accuracy

■ Coarse Timing Detection- Peak of Differential Detection (Averaging over 4 or more Symbols)

■ Fine Timing Detection- Cross-Correlation of Sampled Input Signal- Fine Timing by Interpolation (Fraction of Sampling-Clock Resolution < 1nsec)- Averaging over 4 or more Symbols

Arbitrary Sampling Instant

Detected TimingDetected TimingPeak

Edge

37

CSS Ranging: Correlation

ChirpChirp--Signal PropertySignal Property

τt

ω

t

chirpT

Sω

BWω Tx

Rx

ω∆

ω

( ) exp ( )2

BWchirp s

chirp

s t j t t p tTωω

⎡ ⎤⎛ ⎞= + ×⎢ ⎥⎜ ⎟⎜ ⎟⎢ ⎥⎝ ⎠⎣ ⎦

Dual Properity Freq-offset ( ) caused by Time-offset ( ):

= (Single Frequen cy)BW

chirpTωω τ

ω τ∆ ×

∆

38

CSS Ranging: ToACramerCramer--RaoRao Lower BoundLower Bound

_ 3 8 2 [ ]Range CRB t e mσ = ×Center Frequency: Fc = 2.54e9 Signal Bandwidth: Fbw = 14e6Repetition Period: Tr = 6e-6Pulse Duration: To = Tr x 4/5

0 10 20 30 40 50 60 70 80 90 1000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Distance [m]C

RB

[m]

Cramer-Rao Bound on Range Estimation (IEEE802.15.4a)

P = 1P = 4P = 16P = 64P = 256

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

SNRo [dB]

CR

B [m

]

Cramer-Rao Bound on Range Estimation (IEEE802.15.4a)

P = 1P = 4P = 16P = 64P = 256

P = 1; Tm = 6 μsecP = 4; Tm = 24 μsecp = 16; Tm = 96 μsecP = 64; Tm = 384 μsecp = 256; Tm = 1.536 msec

39

CSS Ranging: ToA

Link BudgetLink BudgetParameter

Chirp-Radio15.4a(2.4GHz)

Chirp-Radio15.4a(2.5GHz)

ZigBee15.4(2.4GHz)

peak payload bit rate(Rb) 1000 250 250 Kbps

Average Tx Power(Pt) 10 10 10 mW

Average Tx Power(10log10(Pt)) 10 10 10 dBm

Tx antenna gain(Gt) 0 0 0 dBi

fc' = sqrt(fminfmax) 2.45 2.45 2.45 GHz

Path loss at 1meter(L1=10n*log10(4pifc'/c)) 40.2 40.2 40.2 dB

Propagation Index (n1: d<=8) 2.0 2.0 2.0

distance 30 30 30 m

path loss at d (L2=10*n1*log10(8))+10*n2*log10(d/8) 29.5 29.5 29.5

Propagation Index (n2: d>8) 2.0 2.0 2.0

Rx antenna gain(Gr) 0 0 0 dBi

Rx power(Pr = Pt+Gt+Gr-L1-L2(dB)) -59.8 -59.8 -59.8 dBm

Average noise power per bit -114.0 -120.0 -120.0 dBm

Rx Noise Figure(Nf) 7 7 7 dB

Average noise power per bit(Pn=N+Nf) -107.0 -113.0 -113.0 dBm

Minimum Eb/No(S) 8.3 6.1 9.6 dB

Implementation Loss(I) 3 3 3 dB

Link Margin(M=Pr-Pn-S-I) 35.9 44.2 40.7 dB

Proposed Min. Rx Sensitivity Level -95.7 -103.9 -100.4 dBm

Required Rx Sensitivity Level -80.7 -88.9 -85.4 dBm

40

CSS Ranging: ToA

HighHigh--Precision Ranging MethodPrecision Ranging Method

Maximum Likelihood Estimation

CSSTx ( )

1

L

i ii

tα δ τ=

−∑

wgn

CrossCorrelation

MaximumLikelihoodEstimation

1st Arrival1τ

IEEE802.15.4a Multipath Channel

Superposition ofMultiple Sinusoidal Waves

Subspace-based Method

CSSTx ( )

1

L

i ii

tα δ τ=

−∑

wgn

SuperResolutionAlgorithm

1st Arrival1τCross

Correlation

IEEE802.15.4a Multipath Channel

41

TechnologyComparisons

42

Technology ComparisonTechnology ComparisonTechnology ComparisonsTechnology ComparisonsCSS Technology Outperform over ZigBee:• SINR Performance: 14.5dB better (Higher Jamming Resistance)• Lower Interference to the other Device (Coexistence)• Higher Jamming Resistance (Enhanced Robustness)

-15 -10 -5 0 5 10 1510-6

10-5

10-4

10-3

10-2

10-1

100IEEE 802 Radio B ER-vs-S INR

SINR [dB ]

Bit

Erro

r Rat

e

802.11b(1M bps)802.11b(2M bps)802.11b(5.5M bps)802.11b(11M bps)802.15.1(1M bps)802.15.3(22M bps)802.15.4(250K bps)802.15.4a(1M bps)802.15.4a(250K bps)

SINR [dB]

Bit

Err R

ate CSS

250KbpsCSS

1Mbps

ZigBee250Kbps

Bluetooth1Mbps

W-LAN

43

Technology ComparisonTechnology Comparison

Technology ComparisonsTechnology Comparisons

ParametersIEEE802.15.4a

2.4GHz CSSIEEE802.15.1 (Bluetooth)

IEEE802.15.4 (ZigBee)

Standard 1 Mbps / 250 Kbps

Data-rate

2 Mbps / 3 Mbps< 1 meter> 200 mph

high< 10 msec

200 meter600-800 meter

Properietary

1 Mbps 250 Kbps

Ranging Accuracy NA NAMobility NA NA

Robustness medium mediumLatency (8 users) 200 msec

~2 sec< 40 msec

Range 10 meter100 meter

25 meter

44

Technology ComparisonTechnology Comparison

Technological advantageStandardized TechnologyPrecision Ranging: Multi-path Resolvability of Chirp SignalFeasibility: High-Precision Ranging with Low sampling-rateCoexistence: Ingress / EgressRegulatory: Use Globally Available 2.4GHz ISM-Band

Intellectual PropertyChannel Estimation for Demodulation and RangingCSK (Chirp-Shift-Keying) Signaling MethodDifferentially Bi-Orthogonal Coding (8-ary, 64-ary)

Competitive advantagePatented Technology Selected as a Baseline of IEEE StandardDBO-CSK Signal requires number of new demodulationtechnology which developed by OrthotronRequired specialized signal processing technique for Ranging

CSS TechnologyCSS Technology

45