project: ieee p802.15 working group for wireless personal area networks (wpans)

July 2004

Kohno NICT, Welborn Freescale, Mc Laughlin decaWave

Slide 1

doc.: IEEE 802.15-04/140r7

Submission

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: [DS-UWB Proposal Update]Date Submitted: [July 2004]Source: [Reed Fisher(1), Ryuji Kohno(2), Hiroyo Ogawa(2), Honggang Zhang(2), Kenichi Takizawa(2)] Company [ (1) Oki Industry Co.,Inc.,(2)National Institute of Information and Communications Technology (NICT) & NICT-UWB Consortium ]Connector’s Address [(1)2415E. Maddox Rd., Buford, GA 30519,USA, (2)3-4, Hikarino-oka, Yokosuka, 239-0847, Japan] Voice:[(1)+1-770-271-0529, (2)+81-468-47-5101], FAX: [(2)+81-468-47-5431],E-Mail:[(1)[email protected], (2)[email protected], [email protected], [email protected] ]Source: [Michael Mc Laughlin] Company [decaWave, Ltd.]Voice:[+353-1-295-4937], FAX: [-], E-Mail:[[email protected]]Source: [Matt Welborn] Company [Freescale Semiconductor, Inc]Address [8133 Leesburg Pike Vienna, VA USA]Voice:[703-269-3000], E-Mail:[[email protected]]

Re: []

Abstract: [Technical update on DS-UWB (Merger #2) Proposal]

Purpose: [Provide technical information to the TG3a voters regarding DS-UWB (Merger #2) Proposal]

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 contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

July 2004


Slide 2

doc.: IEEE 802.15-04/140r7

Submission

Outline

• Merger #2 Proposal Overview – DS-UWB + option of [Common Signaling Mode (CSM) +

MB-OFDM]

• Complexity/Scalability of UWB implementations• Spectral control options for DS-UWB• Performance

July 2004


Slide 3

doc.: IEEE 802.15-04/140r7

Submission

Overview of DS-UWB Proposal

• One of the goals of Merged Proposal #2 is DS-UWB and MB-OFDM harmonization & interoperability through a Common Signaling Mode (CSM)– High rate modes using either DS-UWB or MB-OFDM

• Best characteristics of both approaches with most flexibility

• A piconet could have a pair of DS and a pair of MB devices

– CSM waveform provides control & interoperation between DS-UWB and MB-OFDM

• All devices work through an 802.15.3 MAC– User/device only sees common MAC interface – Hides the actual PHY waveform in use

July 2004


Slide 4

doc.: IEEE 802.15-04/140r7

Submission

The Common Signaling Mode:What Is The Goal?

• The common signaling mode (CSM) allows the 802.15.3 MAC to arbitrate between multiple UWB PHYs– It is an “etiquette” to manage peaceful coexistence between the

different UWB PHYs– Multiple UWB PHYs will exist in the world

• DS-UWB & MB-OFDM are first examples

– CSM improves the case for international regulatory approval• Common control mechanism for a multitude of applications• Planned cooperation (i.e. CSM) gives far better QoS and throughput

than allowing un-coordinated operation and interference

– CSM provides flexibility/extensibility within the IEEE standard• Allows future growth & scalability• Provides options to meet diverse application needs• Enables interoperability and controls interference

July 2004


Slide 5

doc.: IEEE 802.15-04/140r7

Submission

What Does CSM Look Like?One of the MB-OFDM bands!

MB-OFDM (3-band)Theoretical Spectrum

3978

3100 5100

Proposed Common Signaling Mode Band (500+ MHz bandwidth)9-cycles per BPSK “chip”

Frequency (MHz)

DS-UWB Low BandPulse Shape (RRC)3-cycles per BPSK “chip”

July 2004


Slide 6

doc.: IEEE 802.15-04/140r7

Submission

CSM Specifics• We have designed a specific waveform for the CSM

– BPSK modulation for simple and reliable performance– Length 24 spreading codes using 442 MHz chip rate– Harmonically related center frequency of 3978 MHz– Rate ½ convolutional code with k=6– Provides 9.2 Mbps throughput

• Extendable up to 110 Mbps using variable code and FEC rates

• 802.15.3 MAC works great with CSM– CSM can be used for control and beaconing– Negligible impact on piconet throughput (beacons are <1%)

• Requires negligible additional cost/complexity for either radio– MB-OFDM already has a DS mode that is used for synchronization

• This proposal is based on DS-UWB operating with a 26 MHz cell-phone crystal– Very low cost yet terrific phase-noise and accuracy (see GSM spec)

July 2004


Slide 7

doc.: IEEE 802.15-04/140r7

Submission


• DS-UWB proposed as a radio for handheld with– low-cost,– ultra high-rate,– ultra low-power,

• BPSK modulation using variable length spreading codes– Scales to 1+ Gbps with low power - essential for mobile &

handheld applications

• Much lower complexity and power consumption

July 2004


Slide 8

doc.: IEEE 802.15-04/140r7

Submission


1 1

-1 -1……

3 4 5 6 7 8 9 10 11

• Wavelets are modulated with BPSK or QPSK• Symbol is made with an N-chip code sequence• Code is ternary (+1, 0, -1)

• Two wide 50%-bandwidth contiguous bands• Each captures unique propagation benefits of UWB• Bandwidth and Center Frequency Programmable

• Low band provides long wavelet• High band provides short wavelet• Wavelet = 3 cycles, packed back-to-back

N-chips

GHz

• Result is Not-spiky in either Time or Frequency Domain

timevolts

July 2004


Slide 9

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB Signal Generation

Transmitter blocks required to support optional modes

ScramblerK=6 FEC Encoder

Conv. Bit Interleaver

InputData

K=4 FEC Encoder

4-BOKMapper

Bit-to-CodeMapping

PulseShaping

Static Center

Frequency

Gray or Natural mapping

• Data scrambler using 15-bit LFSR (same as 802.15.3)• Constraint-length k=6 convolutional code

• K=4 encoder can be used for lower complexity at high rates or to support iterative decoding for enhanced performance (e.g. CIDD)

• Convolutional bit interleaver protects against burst errors• Variable length codes provide scalable data rates using BPSK

• Support for optional 4-BOK modes with little added complexity

July 2004


Slide 10

doc.: IEEE 802.15-04/140r7

Submission

Data Rates Supported by DS-UWB

Data Rate FEC Rate Code Length Range (AWGN)

28 Mbps ½ 24 29 m

55 Mbps ½ 12 23 m

110 Mbps ½ 6 18.3 m

220 Mbps ½ 3 13 m

500 Mbps ¾ 2 7.3 m

660 Mbps 1 2 4.1 m

1000 Mbps ¾ 1 5.1 m

1320 Mbps 1 1 2.9 m

Similar Modes defined for high band

July 2004


Slide 11

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB Architecture Is Highly Scaleable

• DS-UWB provides low & scalable receiver complexity– ADC can range from 3 bits to 1 bit for super-low power implementation– Rake pipeline & DFE can be optimized to trade off power & cost in

multipath• 16 fingers @ 220, 5 fingers @ 500, 2 fingers @ 1326Mbps• Time duration of DFE scales (shrinks) at shorter range – higher rates.

– FEC can scale w/data rate (k=6 & k=4) or be turned-off for ultra low power– DFE effectiveness and simplicity proven in shipping chips – 3% of area

Pre-SelectFilter

LNA

LPFGA/VGA

GA/VGA

ADC at Chip Rate

ADC at Chip Rate

Rake DFE

LPF

Cos

SinSynch/

Track Logic

AgileClock

1 to 3 bits ADCResolution

1-16 RakeFingers

(or more)

Variable Rate FEC

(or no FEC)

De-interleave& FEC Decode

Variable Equalizer

Span

July 2004


Slide 12

doc.: IEEE 802.15-04/140r7

Submission

UWB System Complexity & Power Consumption

• Two primary factors drive complexity & power consumption– Processing needed to compensate for multipath channel– Modulation requirements (e.g. low-order versus high-order)

• DS-UWB designed to operate with simple BPSK modulation for all rates – Receiver functions operate at the symbol rate– Optional 4-BOK has same complexity and BER performance

• MB-OFDM operates at fixed 640 Mbps (raw)– Designed to operate at high rate, then use carrier diversity

(redundancy) and/or strong FEC to combat multipath fading– Diversity not used above 200 Mbps

July 2004


Slide 13

doc.: IEEE 802.15-04/140r7

Submission

Fundamental Design Approach Differences

• Signal bandwidth leads to different operating regimes– DS-UWB uses 1.326 GHz bandwidth

– MB-OFDM data BW is 412.5 MHz (100 tones x 4.125 MHz/tone)

• Modulation bandwidth induces different fading statistics– DS-UWB (single carrier UWB) results in frequency-selective fading

with relatively low power fluctuation (variance)

– MB-OFDM (multi-carrier) creates a bank of parallel channels that experience flat fading with a Rayleigh distribution (deep fades)

• Motivations for different choices– Different energy capture mechanism (rake vs. FFT)

– Different ISI compensation (time vs. frequency domain EQ)

• These fundamental differences affect both complexity & flexibility– Significant impact on implementation, especially at high rates

July 2004


Slide 14

doc.: IEEE 802.15-04/140r7

Submission

Analog Complexity

• Equivalent analog components have similar complexity

MB-OFDM Analog Components

DS-UWB Analog Components

Similar characteristics

-Antenna-Pre-select filter-LNA

-Antenna-Pre-select filter-LNA

Different characteristics

-Switchable UNII filter-Hopping Frequency Gen-Band filter to reject adjacent channels

-Static UNII filter -Static Frequency Gen -Band filter with no adjacent channels

July 2004


Slide 15

doc.: IEEE 802.15-04/140r7

Submission

Implications of Switchable UNII Filter(slide copied from Doc 03/141r3,p12)

• MB-OFDM is proposed to use the UNII band for Band Group 2 • If the operating BW includes the U-NII band, then interference

mitigation strategies have to be included in the receiver design to prevent analog front-end saturation.

• Example: Switchable filter architecture.– When no U-NII interference is present, use standard pre-select filter.– When U-NII interference is present, pass the receive signal through a

different filter (notch filter) that suppresses the entire U-NII band.

TX

RX

TX/ RXSwitch

Off -chip Pre-select Filter

Off -chip Notch Filter

FilterSwitch

FilterSwitch

Problems with this approach: Extra switches more

insertion loss in RX/TX chain. More external components

higher BOM cost. More testing time.

July 2004


Slide 16

doc.: IEEE 802.15-04/140r7

Submission

Band-Select Filter Complexity

MB-OFDM filter complexity depends on requirements to rejectadjacent-band signal energy

• Depends on whether design is using the guard tones for real data or just PN modulated noise

DS-UWB Filter

Uses single fixed bandwidth – filterprovides rejection for OOB noise & RFI

Bandwidth of DS-UWB > 1500 MHz

Data tonesGuard tones

July 2004


Slide 17

doc.: IEEE 802.15-04/140r7

Submission

MB-OFDM Band-Select Filter Complexity• If guard tones are used for

useful data, band filter must have very steep cut-off– Transition region is very narrow– Only 5 un-modulated tones

between bands (~21 MHz)

• SOP performance also affected by filter design – rejection of adjacent band MAI for SOP

• If guard tones not used for data, then filter constraint is relaxed – Transition region is a wider (15

tones ~62 MHz)– Energy in guard band is

distorted (not useful)– May not meet FCC UWB

requirement for 500 MHz

Tight filter constraint

Relaxedfilter constraint

Filter must reject MAI for SOP

Data tonesGuard tonesFilter response

July 2004


Slide 18

doc.: IEEE 802.15-04/140r7

Submission

Comparison of DS-UWB to MB-OFDM Digital Baseband Complexity for PHY

• Gate count estimates are based on MB-OFDM proposal team methodology detailed in IEEE Document 03/449r2– Gate counts converted to common clock (85.5 MHz) for comparison

• Explicit MB-OFDM gates counts have only been reported by proposers for a 110/200 Mbps implementation– Other estimates of MB-OFDM Viterbi decoder and FFT engine are

provided in IEEE Document 03/343r0• Estimates for MB-OFDM 480 Mbps mode complexity are based

on scaling of FFT engine, equalizer and Viterbi decoder– MB-OFDM estimates of 480 Mbps power available in 03/268r3– Details available in IEEE Document 04/164r0

• Estimates for MB-OFDM 960 Mbps mode details are based on linear scaling of decoder and FFT engine to 960 Mbps– Assumes 6-bit ADC for 16-QAM operation

• DS-UWB gate estimates are detailed in IEEE Document 03/099r4– Methodology for estimating complexity of 16-finger rake, equalizer

and synchronization blocks are per MB-OFDM methodology

July 2004


Slide 19

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB & MB-OFDM Digital Baseband Complexity

• Gate counts are normalized to 85.5 MHz Clock speeds to allow comparison– Based on methodology presented by MB-OFDM proposal team (03/449r3)– Other details of gate count computations in Documents 04/099 and 04/256r0

Component

MB-OFDM(Doc 03/268r3 or 03/343r1)110 Mbps

DS-UWB16-Finger Rake 220 Mbps Raw

3-Bit ADC

DS-UWB32-Finger Rake 220 Mbps Raw

3-Bit ADCMatched filter

Rake [DS] or FFT [OFDM]100K 26K 45K

Viterbi decoder 108K 54K 54K

Synchronization

247K

(Freq Domain)

30K 30K

Channel estimation 24K 24K

Other Miscellaneous including RAM

30K 30K

Equalizer 20K 20K

Total gates @ 85.5 MHz 455K 184K 203K

July 2004


Slide 20

doc.: IEEE 802.15-04/140r7

Submission

Digital Baseband Complexity Comparison at ~1 Gbps

Assumptions: MB-OFDM using 6-bit ADC, FFT is 2.25x & Viterbi is 4x of low rate. *DS-UWB operating with no FEC at 1.362 Gbps

ComponentMB-OFDM

960 Mbps using 16-QAM

DS-UWB

2-Finger Rake 1.326 Gbps

3-bit ADC width

DS-UWB

5-Finger Rake 1.326 Gbps

3-bit ADC widthMatched filter [rake] or

FFT225K 26K 45K

Viterbi decoder 432K 0K* 0K*

Synchronization

297K

(Freq Domain)

30K 30K

Channel estimation 24K 24K

Other Miscellaneous including RAM

30K 30K

Equalizer 50K 50K

Total gates @ 85.5 MHz 954K 160K 179K

July 2004


Slide 21

doc.: IEEE 802.15-04/140r7

Submission

Optional Improvement for Interference Mitigation (Approach 1):Analog type of SSA- Notch generation by using a simple analog delay line:

• Example ： Just Two taps delay line

＋＋

The output signal x(t) is given by

tpwtpwtx 10

By assuming that coefficients w0 and w1 is time- invariant, then its signal in frequency domain is given by

fPewwfX fj 210)(

Now, we set w0=1 and w1=a (a is in real value), we obtain

fPfajfafPaefX fj 2sin2cos11)( 2 A notch is generated at a frequency fn where |X(fn)|2=0, then

012cos22 nfaa The solutions are given by nn ffa 2sin2cos 2 ,

2/mfn （ m=1,2,3,… ） ma cos

As you can see, the coefficient a takes +1 or -1. It leads simple implementation.

where p(t) is a pulse signal , and is delayed time by a delay line D.

however, the coefficient a can take only real value. Therefore,

DD

w0 w1

x(t)

p(t)

The right figure is an example; a is set to 1 and is set at 0.116nsec.

July 2004


Slide 22

doc.: IEEE 802.15-04/140r7

Submission

• DS-UWB systems

X

Spreading code Carrier frequency

x(t)

fcc(t)

b(t)

Tx model 1

X X

p(t)

Pulse signal

4.3GHz (EES)

c(t)=[-1 -1 -1 1 1 -1 1 1]

4.3GHz (EES)

cl(t), c(t)=[-1 -1 -1 1 1 -1 1 1]

Xx(t)

fcc(t)

Tx model 2

X X

p(t)

X

long code

cl(t)

b(t)

Assumption: Chip rate of a long code is the same as bit rate.

• Narrow and Repetitive

(Scrambler) Spreading code Carrier frequencyPulse signal

• Narrow and Repetitive

Example: Example:

Note: These notches are diminished by a bi-phase modulation.

Optional Improvement for Interference Mitigation (Approach 2): Analog type of SSA- Notch generation by using a spreading code

July 2004


Slide 23

doc.: IEEE 802.15-04/140r7

Submission

Optimization of coding rate and spreading factor

Data rate FEC Rate Code Length Range (AWGN)

110Mbps 1/2 6 18.3m

220Mbps 1/2 3 12.9m

• Original VS-DS-UWB

Data rate FEC Rate Code Length Range (AWGN)

110Mbps

1/4 3 13.9m

1/3 4 16.1m

3/4 9 16.9m

220Mbps1/3 2 11.4m

2/3 4 12.9m

• The other combinations

FEC Rate=1/2: [53,75]FEC Rate=1/3: [47,53,75]FEC Rate=1/4: [53,67,71,75]

>

>=

Constraint length is fixed to 6

(Have you already optimized the combinations ?)

July 2004


Slide 24

doc.: IEEE 802.15-04/140r7

Submission

Received Power as a Function Of Node Separation

• Real World DS-UWB Measurements Demonstrate Unique Benefits of UWB

• Not on a 1/R4 curve -- Small dips, no deep fades– = Very robust in highly cluttered environments– = Lower power and minimized potential for interference

-30

-27

-24

-21

-18

-15

-12

-9

-6

-3

0

4 6 8 10 12 14 16 18 20 22 24 26feet

dB

5.31

R

Measured DS-UWB

2R

1

July 2004


Slide 25

doc.: IEEE 802.15-04/140r7

Submission

0

0.02

0.04

0.06

0.08

0.1

PD

F -

4 M

Hz

Fad

ing

-30 -25 -20 -15 -10 -5 0 5 100

0.2

0.4

Received Energy (dB)

PD

F -

1.3

68 G

Hz

Fad

ing

4 MHz MB-OFDM carrier BW fading

Large proportion of deep fades cause bit errors

1.368 GHz BW DS-UWB Fading

NO deep fades!

-30 -25 -20 -15 -10 -5 0 5 10

UWB Fading Distributions Are Key

DS-UWB Has NO Raleigh

Fading

July 2004


Slide 26

doc.: IEEE 802.15-04/140r7

Submission

Many MB-OFDM Tones Suffer Heavy Fading

• MB-OFDM tones suffer heavy fading

• MB-OFDM does not coherently process the bandwidth–FEC across tones is

used

-20 -15 -10 -5 0 510-2

10-1

100

X (dB)

P (

Re

ce

ive

d E

ne

rgy

< x

)

4 M

Hz BW

75 M

Hz

BW

1.4

GH

z B

W

Theor

etica

l Ray

leigh

DS-UWBMB-OFDM

25%

25% of Narrow Band Channels are Faded by 6 dB or more

True coherent UWB like DS-UWB yields significant fading statistics advantage

July 2004


Slide 27

doc.: IEEE 802.15-04/140r7

Submission

110 MbpsRate 11/32 FEC

with 2x DiversityMB-OFDM 1.3 dB Loss

2 2.5 3 3.5 4 4.510-6

10-5

10-4

10-3

SNR (dB)

BE

R

AWGN

MRC OFDM

Simple Diversity Sum OFDM

~1.3 dB with MRC

MB-OFDM Performance Loss Due to Fading• MB-OFDM performance worsens as data rate increases• DS-UWB maintains performance within 1 dB of optimal with low

complexity RAKE200 Mbps

Rate 5/8 FECwith 2x Diversity

MB-OFDM 3.5 dB Loss

3 4 5 6 7 8 910-6

10-5

10-4

10-3

10-2

10-1

100

SNR (dB)

~3.5 dB

MRC OFDMAWG

N

10SNR (dB)

5 6 7 8 9 10 11 12 13 1410

-910

-810

-710

-610

-510

-410

-310

-210

-110

0

4 MHz BW CM-3

AW

GN

~6 dB

480 MbpsRate 3/4 FEC

with No DiversityMB-OFDM 6 dB Loss

July 2004


Slide 28

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB Takes Full Advantage of UWB PropagationDS-UWB Performance Excels As Speed Goes Up

-20 -15 -10 -5 0 5.01

.1

1

X (dB)

P (

Re

ce

ive

d E

ne

rgy

< x

)

4 MHz B

W

75 M

Hz

BW

1.4

GH

z B

W

Theor

etica

l Ray

leigh

MB-OFDM25%

25% of Narrow Band Channels are Faded by 6 dB or more

DS-UWB Does Not Fade

100 150 200 250 300 350 400 450 500-6

-5

-4

-3

-2

-1

0

3/4 FECNo Diversity

11/32 FEC2x Diversity

5/8 FEC2x Diversity

MbpsSpeed

Performance

dB

MB-OFDM

DS-UWB

The Faster the Radio,The More DS is Better

Performance Difference is Natural Consequence

of Channel Physics

DS-UWB Naturally Fits Needs of Multi-Media &

Handheld Devices

July 2004


Slide 29

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB Uses RAKE Receiver with EqualizerFor Optimum Energy Capture and BER

• Use of RAKE is flexible – in receiver, not transmitter– Short range (CM-1) does not need RAKE -- only 4 dB loss from ideal

• No-Rake DS is less power & outperforms MB-OFDM (by 2 dB at 480 Mbps)

– Media Server can use 16-finger RAKE and capture all but 1 dB of available energy in CM-3 – Very high performance

Captured Energy (dB)

0 5 10 15 20 25 30-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

Number of Rake Channels

CM1

CM2

CM3

July 2004


Slide 30

doc.: IEEE 802.15-04/140r7

Submission

DS-UWB Complexity Takes Advantage Of PropagationDS-UWB Power Excels More & More As Data Rate Goes Up

• As UWB Gets Faster– DS – Gets Simpler– MB-OFDM Requires

Higher Emissions, More Complexity

As Range & Speed

DS(Gets Simpler)

MB-OFDM(Gets More Complex)

Signal gets Big

Adapts: Uses less processing Gain

• Shorter codes• 3 2 1 bits ADC as speed

goes up• Less bits in processing

Frozen: Req’s more processing gain to get to high data rate regardless of SNR

• Higher order QAM• More bits in ADC/DAC, FFT/IFFT

Rayleigh Fading

Adapts:Turn FEC Off, (or leave it out)or Use Small (k=4) FEC

Frozen: Serious FEC Required• Speed of K=7 FEC at high rates

killer power & space @ 1Gbps

Delay Spread goes Down

Adapts:DFE covers less time

Frozen:Band Plan Fixed

Speed

High CostComplexity MB-OFDM

DS-UWBSimplerLower Cost

July 2004


Slide 31

doc.: IEEE 802.15-04/140r7

Submission

110 Mbps 90% Outage

Range (meters)

Mean of Top 90%

Range (meters)

CM1 13.5 16.9

CM2 11.7 14.6

CM3 11.4 13.4

CM4 10.8 13.0

Simulation Includes:16 finger rake with coefficients quantized to 3-bits3-bit A/D (I and Q channels)RRC pulse shapingDFE trained in < 5us in noisy channelFront-end filter for Tx/Rx + 6.6 dB Noise FigurePacket loss due to acquisition failure

Multipath Performance for 110 Mbps

July 2004


Slide 32

doc.: IEEE 802.15-04/140r7

Submission


Simulation Includes:8 finger (16 finger) rake with coefficients quantized to 3-bits3-bit A/D (I and Q channels)RRC pulse shapingDFE trained in < 5us in noisy channelFront-end filter for Tx/Rx + 6.6 dB Noise FigurePacket loss due to acquisition failure

220 Mbps

90% Outage Range (m)

8-finger rake

90% Outage Range (m)

16-finger rake

Mean of Top

90% Range (m) 8-finger rake

Mean of Top

90% Range (m) 16-finger rake

CM1 8.4 - 10.2 -

CM2 5.8 7.2 8.2 8.8

CM3 4.9 7.0 6.2 8.4

July 2004


Slide 33

doc.: IEEE 802.15-04/140r7

Submission


Simulation Includes:16 finger rake with coefficients quantized to 3-bits3-bit A/D (I and Q channels)RRC pulse shapingDFE trained in < 5us in noisy channelFront-end filter for Tx/Rx + 6.6 dB Noise FigurePacket loss due to acquisition failure

500 Mbps 90% Outage Range (m)

Mean of Top

90% Range (m)

CM1 3.0 4.8

CM2 1.9 3.2

July 2004


Slide 34

doc.: IEEE 802.15-04/140r7

Submission

AWGN SOP Distance Ratios

Test Distance

1 Interferer Distance Ratio

2 Interferer Distance

Ratio

3 Interferer Distance

Ratio

110 Mbps 15.7 m 0.65 0.92 1.16

220 Mbps 11.4 m 0.90 1.28 1.60

500 Mbps 5.3 m 2.2 3.3 -

• AWGN distances for low band• High band ratios expected to be lower

– Operates with 2x bandwidth, so 3 dB more processing gain

July 2004


Slide 35

doc.: IEEE 802.15-04/140r7

Submission

110Mbps




CM1 0.66 0.86 1.09

CM2 0.64 0.91 1.14

CM3 0.72 0.97 1.24

Multipath SOP Distance Ratios

Test Transmitter: Channels 1-5Single Interferer: Channels 6-10Second Interferer: Channel 99Third Interferer: Channel 100

• High band ratios expected to be lower (3 dB more processing gain)

July 2004


Slide 36

doc.: IEEE 802.15-04/140r7

Submission

Conclusions• Our vision: A single PHY with multiple modes to

provide a complete solution for TG3a– Base mode that is required in all devices, used for control

signaling: “CSM” for beacons and control signaling– Higher rate modes also required to support 110 & 200+ Mbps:– Compliant device can implement either DS-UWB or MB-

OFDM (or both)

• Increases options for innovation and regulatory flexibility to better address all applications and markets

• DS-UWB is shown to have equal or better performance to MB-OFDM in all modes and multipath conditions – for a fraction of the complexity & power

July 2004


Slide 37

doc.: IEEE 802.15-04/140r7

Submission

• Back-up slides

July 2004


Slide 38

doc.: IEEE 802.15-04/140r7

Submission

• DS-UWB systemsNotch generation by using a spreading code

X

Spreading code Carrier

x(t)

fcc(t)

b(t) fPfCfBffX c Frequency domain

Output spectrum is given by convolution Output spectrum is given by convolution

Example:

Tx model

X X

p(t)

Pulse signal

Spectrum of a pulse signal

Spectrum of a spreading code

Convolution

July 2004


Slide 39

doc.: IEEE 802.15-04/140r7

Submission

• Experimental result by UWB Test bed Notch generation by using a spreading code

MATLAB results UWB testbed outputs

July 2004


Slide 40

doc.: IEEE 802.15-04/140r7

Submission

All-Digital Architecture DS-UWB Receiver

• DS-UWB Digital architecture provides scalable receiver complexity

– ADC can range from 3 bits to 1 bit for super-low power implementation

– Rake & DFE can be optimized to trade off power & cost in multipath

– FEC can scale data rate or be turned-off for low power operation

– DFE effectiveness and simplicity proven in shipping chips

Pre-SelectFilter

LNA

LPFGA/VGA

GA/VGA

ADC at Chip Rate

ADC at Chip Rate

Rake DFE

LPF

Cos

SinSynch/

Track Logic

AgileClock

1 to 3 bits ADCResolution

1-16 RakeFingers

(or more)

Variable Rate FEC

(or no FEC)

De-interleave& FEC Decode

Variable Equalizer

Span

July 2004


Slide 41

doc.: IEEE 802.15-04/140r7

Submission

Scalability to Varying Multipath Conditions• Critical for handheld (battery operated) devices

– Support operation in severe channel conditions, but also…– Ability to use less processing (& battery power) in less severe environments

• Multipath conditions determine the processing required for acceptable performance

– Collection of time-dispersed signal energy (using either FFT or rake processing)– Forward error correction decoding & Signal equalization

• Poor: receiver always operates using worst-case assumptions for multipath – Performs far more processing than necessary when conditions are less severe – Likely unable to provide low-power operation at high data rates (500-1000+ Mbps)

• DS-UWB device– Energy capture (rake) and equalization are performed at symbol rate – Processing in receiver can be scaled to match existing multipath conditions

• MB-OFDM device– Always requires full FFT computation – regardless of multipath conditions– Channel fading has Rayleigh distribution – even in very short channels– CP length is chosen at design time, fixed at 60 ns, regardless of actual multipath

July 2004


Slide 42

doc.: IEEE 802.15-04/140r7

Submission

Interference Issues (1)

• Hopped versus non-hopped signal characteristics– ITS and FCC studies are underway

• Goal is to see if interference characteristics of MB-OFDM are acceptable for certification (using DS-UWB/noise/IR for comparison)

• Use of PN-modulation to meet 500 MHz BW– Recent statements by NTIA emphasize importance of minimum – Desire is to ensure protection for restricted bands– DS-UWB bandwidth is determined by pulse shape and pulse

modulation• Spectrum exceeds 1500 MHz

– MB-OFDM bandwidth for data and pilot tones is 466 MHz, guard tones are used to increase bandwidth to 507 MHz• Guard tones “carry no useful information”, only to meet BW req’t. • See authors statements in 802.15-03/267r1 (July 2003, page 12)

July 2004


Slide 43

doc.: IEEE 802.15-04/140r7

Submission

NTIA Comments on Using Noise to meet FCC 500 MHz BW Requirement

• NTIA comments specifically on the possibility that manufacturer would intentionally add noise to a signal in order to meet the minimum FCC UBW 500 MHz bandwidth requirements:

“Furthermore, the intentional addition of unnecessary noise to a signal would violate the Commission’s long-standing rules that devices be constructed in accordance with good engineering design and manufacturing practice.”

• And: – “It is NTIA’s opinion that a device where noise is intentionally injected

into the signal should never be certified by the Commission.”

• Source: NTIA Comments (UWB FNPRM) filed January 16, 2004 available at http://www.ntia.doc.gov/reports.html

July 2004


Slide 44

doc.: IEEE 802.15-04/140r7

Submission

FCC Rules Regarding Unnecessary Emissions

• FCC Rules in 47 CFR Part 15 to which NTIA refers:

“§ 15.15 General technical requirements.

(a) An intentional or unintentional radiator shall be constructed in accordance with good engineering design and manufacturing practice. Emanations from the device shall be suppressed as much as practicable, but in no case shall the emanations exceed the levels specified in these rules.”