May. 2009 FRANCE TELECOM /CEA-LETI/THALES doc.: IEEE 802. 15-09-0324-02-0006 Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks.

May. 2009

FRANCE TELECOM /CEA-LETI/THALES

doc.: IEEE 802. 15-09-0324-02-0006

Slide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: France Telecom / CEA / Thales final proposalDate Submitted: May 4th, 2009Source: Jean Schwoerer (1), Laurent Ouvry (2), Arnaud Tonnerre(3)Companies:

(1) France Telecom R&d, 28 chemin du vieux chênes, 38240 Meylan, Cedex, FRANCE (2) CEA-LETI, 17 rue des Martyrs 38054, Grenoble Cedex, FRANCE (3) THALES, 146 boulevard de Valmy, 92704 Colombes, France

Voice: (1) +33 4 76 76 44 83, (2) +33 4 38 78 93 88, (3) +33 1 46 13 28 50 E-Mail: (1) [email protected], (2) [email protected], (3) [email protected],

Abstract: Response to IEEE 802.15.6 call for proposals

Purpose: PHY and MAC proposal based on UWB impulse radio for the IEEE 802.15.6 CFP

Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.

Release: The contributors acknowledge and accept that this contribution becomes the property of IEEE and may be made publicly available by P802.15

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 2

List of Authors

• France Telecom – Jean Schwoerer, Benoit Miscopein, Stephane Mebaley-Ekome (1)

• CEA-LETI – Laurent Ouvry, Raffaele D’Errico, François Dehmas, Mickael Maman, Benoit Denis, Manuel Pezzin (2)

• THALES – Arnaud Tonnerre (3)

• University of Surrey, UK – Ehsan Z. Hamadani • INSA-Lyon, FR – Jean-Marie Gorce

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 3

Outline• Introduction• PHY proposal

– Advantages of UWB– Band Plan and PLL reference diagram– Pulse Repetition Frequency, Preamble, Modulation– Variable bit rate & throughput– Link Budget, Performances– Feasibility examples

• MAC elements proposal– Beacon-based mode: Evolution of IEEE 802.15.4 MAC– Beacon-disabled mode: Preamble sampling approach– Upper layers responsibility

• Conclusions & References

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 4

PHY Proposal

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 5

Introduction

• Proposal main features:1. Based on IEEE802.15.4a-2007 where a very

reduced set of mode is selected for the BAN context

2. UWB Impulse-radio based3. Support for different receiver architectures

(coherent/non-coherent)4. Flexible modulation format5. Support for multiple rates6. Support for multiple SOP

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Slide 6

Advantages of UWB

• Low radiated power• Low PSD, low interference, low SAR• High co-existence with existing 802.x standards• Real potential for low power consumption

• Large bandwidth worldwide• Spectrum is worldwide available• Robust to multipath and fast varying channels

• Flexible, scalable (e.g. data rates, users)

• Low complexity HW/SW solutions in advanced development (eg 802.15.4a)

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Slide 7

Complexity vs. data rate & coverage

Coherent Rake IR-UWB EQ IR-UWB

FM-UWBNon coherent IR-UWB

Non coherent IR-UWBCoherent IR-UWB

LDR

Com

plex

ity /

Pow

er

MDR HDR

Applications Coverage

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Slide 8

Band plan (selection from 15.4a)Band Group

Channel Number

Center Frequency Chip Rate

Mandatory/Optional(MHz) (MHz)

1

1 3494,4 499,2 Optional

2 3993,6 499,2 Optional

3 4492,8 499,2 Mandatory in low band

2 5 6489,6 499,2 Optional

6 6988,8 499,2 Optional

2 8 7488 499,2 Optional

9 7987,2 499,2 Mandatory in high band

10 8486,4 499,2 Optional

2 12 8985,6 499,2 Optional

13 9484,8 499,2 Optional

14 9984 499,2 Optional

Comparison with 15.4a : •Only 500 MHz bandwidth channels•No sub-GHz band

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Slide 9

Band plan versus regulation for UWB

-100

-90

-80

-70

-60

-50

-40

-30

-20

0 1 2 3 4 5 6 7 8 9 10 11 12

Frequency (GHz)

PS

D (

dB

m/M

Hz)

EU Above 6GHz decision

EU Mitigationtechniquesbelow 4.8 GHz

EU Phasedapproach below4.8 GHz

FCC emissionlimits for UWBindoor devices

Japan (w/omitigationtechniques)

Japan (withmitigationtechniques)

21 653 8 109 12 13 14

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Slide 10

PLL Reference Diagram

OscillatorPhase

DetectorLPF VCO

÷ N

XTALfcomp

fX

÷ M

fc

fs = 499.2 MHz

Channel Fc fX fcomp N M1 3494.4 MHz 9.6 MHz 9.6 MHz 7 52

2 3993.6 MHz 9.6 MHz 9.6 MHz 8 52

3 4492.8 MHz 9.6 MHz 9.6 MHz 9 52

For channels 5,6,8,9,10,12,13,14 (high band), the factor N becomes respectively 13,14,15,16,17,18,19,20

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Slide 11

Pulse Repetition Frequency• Selected value

– 15.6 MHz PRF (64.10 ns of pulse repetition period PRP)– Use of binary codes, No bursts => mean PRF = peak PRF

• Rationale– Typical channel delay spread for indoor applications below 25

ns in 90% of channel realizations => very limited ISI (or IPI)– Integer relationship with base frequency of the bandplan (499.2

MHz / 32) => no fractional PLL– Maximized Pulse amplitude

• => better for transmitter power consumption (between-pulses duty cycling)

• => better for pulse detectability in the receiver• => better for threshold crossing receivers • => compatible with low voltage CMOS technologies without I/O

« tricks » (around 780 mVp-p)– A single value => simplicity– Compatible with bit rate scalability with short spreading factors– No high speed clock / long FIRs filters to generate or correlate

with bursts of pulses

10 15 20 25 30 350

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

(ns)

Cum

ulat

ive

prob

abili

ty

802.15.6 UWB: dealy spread & mean delay computed from PDP model (NICT)

Delay spread

Normal fitMean delay

Normal fit

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Slide 12

• PRF is the same as one of the mean PRF in 15.4a

• Sp code duration:

– Example with N=31 : Tpsym = 31 * PRP = 1.9871 us

– To be checked if enough for a correct (Pd,Pfa) versus complexity

• Number of Sp codes in the preamble

– Example with Nsp = 16 : Tsync = 16 * Tpsym = 31.7936 us

– This is probably a maximum value

– To be checked if enough for a correct (Pd,Pfa) versus overhead

Sp code duration N*PRP

PRP = 64.10 ns

Preamble

Sp code : binary. Length TBD. Unique.

10 11 12 13 14 15 16 17 18 19 2010

-4

10-3

10-2

10-1

100

Es/N0 (dB)

MD

: P

roba

blity

of

mis

s de

tect

ion

8 ns integration AWGN channel 0.5 GHz bandwidth N : 128 pulse repetitions (Ns =8)

total pMD

total pFA

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Slide 13

Modulation

• PRF is ~ the same as one of the mean PRF in 15.4a • Spreading code length Sd

– Example with N=7 (BARKER CODE) : Symbol duration Ts = 7 * PRP = 0.4488 us

• Modulation : 1 bit per symbol + second bit used for redundancy OR non coherent demod– DBPSK : BPSK with differential encoding (at symbol level)

• Sub-optimal but easier to implement and less sensitive to clock drift

– DBPSK + PPM : the whole S code can be shifted within the PRP with ½ the PRP value• Does not affect the mean PRF value and the spectrum shape, Is simple to implement (though a little more complex

than pure DPBSK), Is compatible with non coherent / threshold crossing detectors, Is ISI compatible in the BAN context

– DBPSK + chip-PPM : each chip of the code is shifted according to the chip value => selected option

Sd = +1 +1 +1 −1 −1 +1 −1

Symbol duration = 7 pulses ~ 448.8 ns

PRP = 64.10 nsSymbol : +1 Symbol : -1

Objective: to afford (differential) coherent and non coherent receivers

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Slide 14

Modulation : Bit-DBPSK + 2-PPM(an orthogonal keying modulation)

PRP = 64.102 ns

ET = 16.026 ns

Barker code of length 7: 1 1 1 -1 -1 1 -1

+1

-1

Ts = 448.8 ns (symbol rate = 2.23 MS/s

Bit 1

Previous bit 1

Barker code of length 7: 1 1 1 -1 -1 1 -1

Ts = 448.8 ns (symbol rate = 2.23 MS/s

Bit -1

Previous bit 1

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Slide 15

Variable bit rates• Bit rates

– Bit rate is adjusted with the number of pulses per symbol keeping a constant mean PRF

– 2.22 Mbit/s is the default uncoded data rate – 5.2 and 15.6 Mbit/s are mandatory => No additional complexity & allows to

reduce channel use– 31.2 Mbit/s is proposed optionally for coherent receiver (uses both PPM &

DPBSK)– Proposed FEC : systematic RS (63,55) as in 15.4a (maximum efficiency ~0.87)– The lowest rate is a compromise between “Tx_on time” and range (+clock drift

compensation requirements).

Mean PRF (MHz)Nb. (N) pulses per

symbol(barker code length)

Symbol duration (ns)

Bit rates

Symbol rate (MHz)Bit rate(Mbps)

PSK or PPM

Coded Bit rate(Mbps)

PSK or PPM

15.6 7 448.7 2.229 2.229 1.95

15.6 3 192.3 5.2 5.2 4.54

15.6 1 64.1 15.6 15.6 13.62

15.6 1 64.1 15.6 31.2 (PPM & BPSK) 27.24 (PPM & BPSK)

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Slide 16

Parameter Value Unit Comment

PSD -41,3 dBm/Mhz

fc (arithmetic center frequency) 4492,8 MHz

Bandwidth @ -10dB 680 MHz

Peak Payload bit rate (Rb) 2,229 Mbps

Distance (d) 3 m According to TRD

Maximum Tx Power (PT) -13,0 dBm

Pulse shaping losses & Power backoff 4,5 dB 1-2dB improvement feasible

Tx Power (PT) -17,5 dBm

Tx antenna gain (GT) -3 dBi Shared between Tx and Rx

f’c: (geometric center frequency) 4479,9 MHz

Path Loss @ 1m: L1 = 20log10(4.p.f’c / c) 45,46 dB

Path loss exponent after 1 meter (Alpha) 2,00 - According to TRD / CM4

Path Loss @ d m: L2 = 10*Alpha*log10(d) 9,54 dB

Total Path Loss : L= L1+L2 65,0 dB

Rx Antenna Gain (GR) 0 dBi

Rx Power (PR = PT + GT + GR – L) -85,5 dBm

Average noise power per bit : N = -174 + 10log10(Rb) -110,5 dBm

Rx noise figure (NF) 6 dB

Average noise power per bit (PN = N + NF) -104,5 dBm

Minimum required Eb/N0 (S) 9 dB

Implementation Loss (I) 5 dB

Link Margin (M = PR - PN – S – I) 5,0 dB

Proposed Min. Rx Sensitivity Level -90,5 dBm

Link budget

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Slide 17

Performances analysis methodology and channel models

• Goal: – Get/discuss performances at a link budget / outage probability level

with the different channel models at the default 2.2 Mbps rate before digging into the design level performances

• Methodology:– Perform extra measurements at CEA-Leti (for UWB 3-5GHz but also

for 2.4 GHz)– Complement the IEEE802.15.6 CM3 UWB channel model with extra

measurements and models and compare channel models with each other

– Move towards a scenario based approach• Scenario = [at least] given (Tx,Rx) couple + given generic environment +

given generic movement • Justified by the huge dispersion of the BAN radio channel

– Calculate outage probabilities given the path loss and shadowing statistics

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Slide 18

Performances: channel path loss models• Available CM3 UWB channel models

as in TG6 document : – A (source NICT)

• Indoor and anechoic

– B (source IMEC)• Anechoic

– C (source Samsung)• Indoor and anechoic

• Conclusion– Huge dispersion (tens of dBs)

between models

– Distance is not a relevant parameter to get a path loss model

– Coming back to the scenario based channel characterization is proposed

• Reference– Roblin C.; D'Errico R.; Gorce J.M.;

Laheurte J.M ; Ouvry L., « Propagation channel models for BANs: an overview », COST 2100, 16/02/2009 - 18/02/2009, Braunschweig , Germany

100 200 300 400 500 600 700 800 900 100040

50

60

70

80

90

100

d (mm)

PL (

dB

)

Comparison of IEEE802.15.6 models and others - UWB 3-5 GHz - Anechoic chamber or equivalent

3.1-10.6 GHz - 802.15.6 CM3 - NICT +-1s

3-10 GHz - IMEC "front"

2-12 GHz - ENSTA "front" (up to 500mm)

4-5 GHz - ENSTA "front" (up to 500mm)

3.1-5.1 Ghz - Samsung "Standing"

3.1-5.1 Ghz - Samsung "Sitting"

3.1-5.1 Ghz - Samsung "Forward movement" +-1s

3.1-5.1 Ghz - Samsung "Side movement" +-1s

100 200 300 400 500 600 700 800 900 100040

50

60

70

80

90

100

d (mm)

PL (

dB

)

IEEE802.15.6 - UWB 3-5 GHz - Indoor

3.1-10.6 GHz - 802.15.6 CM3 - NICT +-1s

3.1-5.1 Ghz - Samsung "Standing"

3.1-5.1 Ghz - Samsung "Sitting"3.1-5.1 Ghz - Samsung "Forward movement" +-1s

3.1-5.1 Ghz - Samsung "Side movement" +-1s

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Slide 19

Performances: extra channel measurements• 2-5 GHz, indoor and anechoic, 7 subjects,

standing/walking/running, scenarios as depicted below

• Log normal path loss model. Shadowing and small scale fading modeled separately.

• Reference : D'Errico R.; Ouvry L.,“Time-variant BAN channel characterization” TD(09)879, COST2100, 18-19/05/2009, Valencia, Spain (Measurement set up details available on request)

Chest Right Thigh Right Wrist Rigth Foot-70

-65

-60

-55

-50

-45

-40

RX antenna position

Cha

nnel

Gai

n [d

B]

TX on Hip

Still, ISMWalking, ISM

Running, ISM

Still, UWB

Walking, UWBRunning, UWB

Right Ear Hip Right Wrist Rigth Foot-70

-68

-66

-64

-62

-60

-58

-56

-54

-52

RX antenna position

Cha

nnel

Gai

n [d

B]

TX on Left Ear

Still, ISMWalking, ISM

Running, ISM

Still, UWB

Walking, UWBRunning, UWB

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 20

Performances: extra channel measurements• On previous page:

– Error bar @ 1 std of mean channel gain over subjects

– Without the slow shadowing std– 2.4 GHz and 3-5 GHz for

comparison• On this page

– UWB 3-5 GHz only– Error bar @ 2 stds of mean

channel gain and slow shadowing (95% confidence interval)

• Conclusions– 2.5% outage probability @ ~-70dB

channel loss for the 8 scenarios in indoor conditions

– Higher outage in anechoic chamber depending on the scenario (not shown here)

Chest Thigh Right wrist Right foot-90

-85

-80

-75

-70

-65

-60

-55

-50

-45

-40

RX antenna position (scenario)

Cha

nnel

Gai

n [d

B]

Indoor - Transmitter on Hip - Mean channel gain + 95% interval

Still

WalkingRunning

Right ear Hip Right wrist Right foot-90

-85

-80

-75

-70

-65

-60

-55

-50

-45

-40

RX antenna position (scenario)

Cha

nnel

Gai

n [d

B]

Indoor - Transmitter on Left Ear - Mean channel gain + 95% interval

Still

WalkingRunning

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Slide 21

Performances : outage probability• Starting from:

– The link budget• PTx + antenna = -20.5 dBm• Sensitivity = -90.5 dBm

– Includes 6dB NF, 5dB I.L. and 9dB min required EbN0• 70dB total link margin

– The different scenario based path loss models• CM3 UWB A back to the scenarios• CM3 UWB C back to the scenarios• CEA-Leti’s measurements

• Get the outage probability performance for an EbN0 – Probability that the received power is higher than the receiver

sensitivity– from the proposed -90.5dBm sensibility (2.2 Mbps)– through to -87.8dBm (5.2 Mbps)– and to -82dBm (15.6 Mbps)

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Slide 22

-91 -90 -89 -88 -87 -86 -85 -84 -83 -82 -8110

-4

10-3

10-2

10-1

100

Minimum required Eb/N0 (dB)

Out

age

prob

abili

ty w

ith m

ovem

ent

shad

owin

g

Indoor - Transmitter on Hip

Indoor - Hip to chest - StillIndoor - Hip to thigh - Still

Indoor - Hip to right wrist - Still

Indoor - Hip to right foot - StillIndoor - Hip to chest - Walking

Indoor - Hip to thigh - Walking

Indoor - Hip to right wrist - Walking

Indoor - Hip to right foot - WalkingIndoor - Hip to chest - Running

Indoor - Hip to thigh - Running

Indoor - Hip to right wrist - RunningIndoor - Hip to right foot - Running

Performances : outage probability

5% of channel realizations threshold

2.2 Mbps proposed sensibility

Area where target PER is obtained

5.2 Mbps proposed sensibility X legend : sensitivity (dBm)

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Slide 23

Performances : outage probability

-91 -90 -89 -88 -87 -86 -85 -84 -83 -82 -8110

-4

10-3

10-2

10-1

100


Out

age

prob

abili

ty w

ith m

ovem

ent

shad

owin

g

Indoor - Transmitter on Left Ear

Indoor - Left ear to right ear - StillIndoor - Left ear to hip - Still

Indoor - Left ear to right wrist - Still

Indoor - Left ear to right foot - StillIndoor - Left ear to right ear - Walking

Indoor - Left ear to hip - Walking

Indoor - Left ear to right wrist - Walking

Indoor - Left ear to right foot - WalkingIndoor - Left ear to right ear - Running

Indoor - Left ear to hip - Running

Indoor - Left ear to right wrist - RunningIndoor - Left ear to right foot - Running

5% of channel realizations threshold

2.2 Mbps proposed sensibility

Area where target PER is obtained

5.2 Mbps proposed sensibility X legend : sensitivity (dBm)

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Slide 24

Performances : scenario based outage probability

• Tentative consolidation of – CM3 A (NICT) – CM3 C (Samsung)– CEA-Leti’s measurements

for four indoor scenarios : – Hip-left ear– Hip-right wrist– Hip-thigh– Hip-chest– (others available as well,

including anechoic chamber cases)

• Needs further update to refine comparisons, but aims at opening discussions

9 10 11 12 13 14 15 16 17 1810

-6

10-5

10-4

10-3

10-2

10-1

100

Hip - Chest


Out

age

prob

abili

ty

Leti - Indoor - Hip to Chest - Still

Leti - Indoor - Hip to Chest - Walking

Leti - Indoor - Hip to Chest - Running

NICT - Indoor - Chest to Abdomen - lying

9 10 11 12 13 14 15 16 17 1810

-4

10-3

10-2

10-1

100

Hip - Thigh


Out

age

prob

abili

ty

Leti - Indoor - Hip to Thigh - Still

Leti - Indoor - Hip to Thigh - WalkingLeti - Indoor - Hip to Thigh - Running

NICT - Indoor - Thigh to Abdomen - Lying

9 10 11 12 13 14 15 16 17 1810

-4

10-3

10-2

10-1

100

Left ear - Hip


Out

age

prob

abili

ty

Leti - Indoor - Left ear to Hip - Still

Leti - Indoor - Left ear to Hip - Walking

Leti - Indoor - Left ear to Hip - Running

NICT - Indoor - Left ear to Abdomen - Lying9 10 11 12 13 14 15 16 17 18

10-4

10-3

10-2

10-1

100

Hip - Right wrist


Out

age

prob

abili

ty

Leti - Indoor - Hip to Right wrist - Still

Leti - Indoor - Hip to Right wrist - Walking

Leti - Indoor - Hip to Right wrist - RunningNICT - Indoor - Left hand to Abdomen - Lying

Samsung 3.1-5.1GHz - Indoor - Left waist to Right wrist - Forward direction

Samsung 3.1-5.1GHz - Indoor - Left waist to Right wrist - Side direction

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Slide 25

8 9 10 11 12 13 14 15 16

10-5

10-4

10-3

10-2

10-1

100

DBPSK with 3-fingers RAKE receiver BER/PER simulations over the CM3 A channel

EbN0 (dB)

BER mode 2.2 Mbps uncodedPER mode 2.2 Mbps uncodedPER mode 2.2 Mbps codedBER mode 2.2 Mbps codedBER mode 5.2 Mbps uncodedPER mode 5.2 Mbps uncodedBER mode 5.2 Mbps codedBER mode 5.2 Mbps codedPER mode 15.6 Mbps uncodedBER mode 15.6 Mbps uncodedBER mode 15.6 Mbps codedPER mode 15.6 Mbps codedBER in AWGN uncodedPER in AWGN uncoded

Performance : EbN0 requirements (DBPSK)• Conditions: DBPSK, 20 bytes PSDU, CM3 A channel

• Same results (with better PER floor in highest rate) for 256 bytes

Note: Input uncoded BER to reach the target PER : 5e-5 for PER=10% with 256 bytes PSDU6e-5 for PER = 1% with 20 bytes PSDU (15.4/4a)

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Slide 26

Conclusions on link performances on the different channel

• The proposed link budget and system specification makes the UWB proposal feasible for most of the scenarios

– outage of 5% as in TRD – 1e-2 PER for 20 bytes PSDU, or – 1e-1 PER for 256 bytes PSDU– Actual EbN0 requirement still to refine (current simulation with

realistic receiver on CM3 gives 13dB after RS decoding, within the proposed IL values, but the CM3 multipath model is questionable)

• However, large variations between the different models (CM3 A is optimistic, CM3 C is pessimistic, CM3 B and CEA-Leti’s measurement are median)

• Further analysis in the 7.25-8.5 GHz band is necessary

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Slide 27

Transmitter 4.5 GHz

Max amplitude

Min Mean PRF

Modulations

Power consumption

: 700mVpp

: 3.9MHz

: OOK, PPM, BPSK

: 0.7mW

Receiver 4.5 GHz

S11

IIP3

Input BW

Max sensitivity

Power consumption (analogue + digital RF)

: <-15dB

: -15dBm

: 850MHz

: -78dBm

: 17mW

• RF part only

– Total Power consumption: 34mW (Rx:17 + Tx:0.7 + I/O:16.3)

– Max data rate: 31Mb/s (@ max PRF)

– RF receiver energy efficiency : 1.1nJ/b @ 31Mb/s

– RF transmitter energy efficiency : 23pJ/b @ 31Mb/s

• Overall transceiver

– DBPSK Digital BB: 347 kbps - 1 Mbps

– Total RX power consumption:

• 44mW peak in synchronization mode(RF=17 + BB=27)

• 25mW in demodulation mode(RF=17 + BB=8)

Background design know-how (see references)

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Slide 28

Conclusions• Proposal based upon UWB impulse radio alt-PHY of 15.4a

– Advantage• Early implementations exist: experienced proposal• Selection of the most relevant modes and their adaptation to the BAN context (note: 15.4a mandatory

mode is NOT the selected option for 15.6)• A standard exists which will speed up the 15.6 standard drafting steps

– Modulation:• DBPSK provide robustness for a limited complexity & 2PPM allow several receiver implementations• RS FEC help to improve link budgets and parity bit will improve robustness of the DBPSK receiver

• System tradeoffs- Variable bit rates allow to accommodate all applications envisaged in TG6- Minimizing talk time improve energy consumption, SOP performances, and regulatory

compliance

• Flexible implementation of the receiver– Compatible with a lot of UWB detectors (coherent, differential, energy, threshold crossing)– FEC decoder is optional

• Fits with multiple technologies– Compatible with implementation in low voltage CMOS– Very low power integrated solutions already proven (thus to be adapted)

• The very low transmit power is a very attractive feature for the UWB PHY adoption

Will permit good compromises between cost, performances and energy consumption

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Slide 29

MAC elements proposal

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Slide 30

MAC layer

• BANs may be coordinated most of the time– The coordinator can allocate a negotiated bandwidth to QoS

demanding nodes (data rate, BER, latency)– A beacon based approach is adapted

• Some applications imply a lower channel load– A beacon-free mode is more efficient

• An IEEE 802.15.4-like MAC layer is a good base for BANs– With a beacon-enabled mode including TDMA and Slotted-ALOHA

(for UWB) with relaying– With an enhanced beacon-free mode by using Preamble Sampling

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Slide 31

Beacon-based MAC mode

• BAN requires above all:– Relaying capability: to cope with low-power

emission and severe NLOS conditions• Would be limited to 2-hops in the BAN context

– Reliability: high level of QoS for critical / vital traffic flows

• Proposed architecture– Mesh network centralized on the gateway

• Full mesh topology based on a scheduling tree

• Guaranteed access for management and data messages (real TDMA)

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Slide 32


• Superframe structure – Based on 802.15.4

– Inclusion of a control portion for management messages• The control portion shall be large enough to allow dynamic changes of

topology

– The CAP is minimized, mostly used for association using slotted ALOHA

Beaconperiod

Beaconperiod

Requestperiod

Requestperiod

Topo mgmtperiod

Topo mgmtperiod

Control portionControl portion Data portionData portion

CAPCAP CFPCFP InactiveInactive

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 33


• Fine structure– Superframe is divided equally into slots– Use of Minislots in the Control portion

• Provides flexibility: adaptation to different frame durations

– Guaranteed Time MiniSlot (GTMS) shall be introduced in CFP

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 34


• Control portion structure– Beacon period

• The beacons are relayed along the Scheduling Tree• The beacon-frame length shall be minimized• Beacon alignment procedure shall be used

– Request period• Request period is a set of GTS dedicated to allocation demands• Transmission from the leaves to the coordinator

– Topology management period• Hello frames, for advanced link state procedure• Scheduling tree based update

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 35

Beacon-free MAC mode

• However, some situations might not require a beacon-enabled MAC protocol (see references.) – Symmetric or asymmetric network, low communication rate

and small packets– Network set-up, coordinator disappearance, etc

• In such conditions, the downlink is an issue : nodes must be powered-up to receive data from the coordinator (e.g. polling/by-invitation MAC scheme)

• We propose a Preamble Sampling MAC protocol for UWB

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 36


• Preamble Sampling principles:– Nodes periodically listen to the channel. If it is clear, they go back

to sleep; conversly, they keep on listening until data

– Nodes are not synchronized but share the wake up period (TCI)

– A packet is transmitted with a preamble as long as TCI

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 37

Beacon-free mode

• Preamble sampling protocols are known to be the most energy efficient uncoordinated MAC protocols

• TCI depends on the traffic load and the TRX consumption (TX/RX/listen modes)

• Can be of the order of 100 ms

• The preamble is a network specific sequence– Either a typical wake-up signal

– Or a preamble with modulated fields (e.g. @, time left to data)

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 38

Beacon-free MAC mode• To comply with LDC regulation in the lower band (e.g. Europe),

the preamble can be relayed by the BAN nodes (up to 5ms long bursts)

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 39


• Mode 0: only one burst per device is emitted

• Mode 1: burst is re-emitted by a device, under the LDC limit, until a neighbour relays

• Mode 2: same as mode 1 + former relays, with emission credits left, can relay again

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 40

Upper Layers responsibility

• Enabling/disabling beacons switching procedure– From beacon-free to beacon-based mode

• BAN formation (coordinator election)

• New coordinator election if former coordinator leaves

• Can be triggered by a user requesting a link with high QoS

– From beacon-based to beacon-free mode• Fallback mode if the coordinator leaves

• If the required BW (rate of GTS requests) is below a given threshold and requested QoS is adequate

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 41

Conclusions on MAC

• Propose a combination of– A Beacon-based true TDMA mode

including fast relaying and mesh support– A Beacon-free mode using preamble

sampling and extra features adapted to UWB

May. 2009


doc.: IEEE 802. 15-09-0324-02-0006

Slide 42

References

• 15-08-0644-09-0006-tg6-technical-requirements-document.doc• M. Pezzin, D. Lachartre, « A Fully Integrated LDR IR-UWB CMOS Transceiver

Based on "1.5-bit" Direct Sampling », ICUWB 2007, Singapore, September 2007• D.Lachartre, B. Denis, D. Morche, L. Ouvry, M. Pezzin, B.Piaget, J. Prouvée, P.

Vincent, « A 1.1nJ/b 802.15.4a-Compliant Fully Integrated UWB Transceiver in 0.13μm CMOS», ISSCC 2009, San Francisco, February 2009

• European ICT PULSERS II and ICT EUWB projects deliverables• French ANR "BANET" project• Roblin C.; D'Errico R.; Gorce J.M.; Laheurte J.M ; Ouvry L., « Propagation

channel models for BANs: an overview », COST 2100, 16-18/02/2009, Braunschweig , Germany

• D'Errico R.; Ouvry L.,“Time-variant BAN channel characterization” TD(09)879, COST2100, 18-19/05/2009, Valencia, Spain

• European ICT SMART-Net project deliverables• Timmons, N.F. Scanlon, W.G. "Analysis of the performance of IEEE 802.15.4

for medical sensor body area networking", IEEE SECON 2004, Santa Clara, Ca, October 2004

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 43

Questions ?

May. 2009


doc.: IEEE 802. 15-09-0324-02-0006

Slide 44

Back-up slides

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 45


• In this collaborative scheme, the preamble burst can composed of– Destination adress (compuls.)

– Time left to data (compuls.)

– Packet length

– Source adress

• Need for a relaying collision resolution policy– Based on the wake-up instant during the burst (priority is

given to the node which has detected the burst first)

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 46


• Relationship between wake-up instant in the burst and back-off length can be of any kind (linear, logarithmic, exponential…)

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 47


• Collaborative scheme is very flexible– Nodes can relay once or up to the emission maximum

duration (50 ms in Europe)

– If the source listens to the relays, it can get the wake-up schedules of its neighboors

– The destinator can emit a specific burst to notify the source• Possibility to stop the relay process

• Reduction of the latency because the source can anticipate the payload emission

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 48

Beacon-free MAC mode• Exemple of latency reduction

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Slide 49

Upper layers responsibility

• Management of cooperative transmissions

– One way relay channel (OWRC)A single source node transmits data to a single destination node with the help of some relay nodes

– Two way relay channel (TWRC)Two nodes like to communicate to each other through the help of a relay

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doc.: IEEE 802. 15-09-0324-02-0006

Slide 50

Upper layers responsibility

• Cooperation possibilities– Low data rate transmission

• Complexity of involved nodes and power consumption are the main issues

• Low complexity cooperative techniques may be used

– High data rate transmission • Increasing data rate and channel availability are more important• Decode and forward schemes in OWRC or even network coding with

TWRC are more suitable

May. 2009 FRANCE TELECOM /CEA-LETI/THALES doc.: IEEE 802. 15-09-0324-02-0006 Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks.

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