Doc.: IEEE 15-05-0707-01-004a TG4a November 30, 2005 Gian Mario Maggio (ST)Slide 1 Project: IEEE...

November 30, 2005

Gian Mario Maggio (ST)Slide 1

Doc.: IEEE 15-05-0707-01-004a

TG4a

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

Submission Title: TG4a UWB-PHY overview.Date Submitted: November 30, 2005Source: Gian Mario Maggio (STMicroelectronics)Contact: Gian Mario MaggioVoice: +41-22-929-6917, E-Mail: [email protected]: Review of the 802.15.4a UWB-PHY.Purpose: To provide a summary of the current status of the 802.15.4a UWB-PHY

and an outlook of the future TG4a work for this portion of the standard. 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.

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

802.15.4a UWB-PHY(http://www.ieee802.org/15/pub/TG4a.html)

Gian Mario Maggio

STMicroelectronics

November 30th, 2005

http://www.ieee802.org/15/pub/TG4a.html

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Doc.: IEEE 15-05-0707-01-004a

TG4a

Outline• IEEE 802.15.4a • UWB-PHY• Band-plan• Data rates• Preamble• Modulation• Spreading• Coding• Waveforms

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TG4a

802.15.4a Overview

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TG4a

802.15.4a: Introduction• The IEEE 802.15 Low Rate Alternative PHY Task Group (TG4a) for Wireless Personal Area Networks (WPANs) has defined a project for an amendment to 802.15.4 for an alternative PHY• The main interest is in providing communications and high-precision ranging/localization capability (1 meter accuracy), high aggregate throughput; as well as adding scalability to data rates, longer range, and lower power consumption and cost• These additional capabilities over the existing 802.15.4 standard are expected to enable significant new applications and market opportunities

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802.15.4a: Short History• 802.15.4a became an official TG in March 2004

(committee work tracing back to November 2002)• The committee is actively drafting an alternate PHY

specification for the applications identified• In March 2005, the baseline specification was

selected (without enacting down-selection procedures) baseline with 100% approval

• The baseline is two optional PHYs consisting of:1. UWB Impulse Radio (operating in unlicensed UWB spectrum)2. Chirp Spread Spectrum (operating in unlicensed 2.4GHz

spectrum)• The UWB Impulse Radio will be able to deliver

communications and high precision ranging

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TG4a

802.15.4a: Schedule5 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 Formed x

Call for application created July 2003Selection criteria documentx x

Call for intent to propose x

Call for proposal issued x

Channel Models Release x x x x

Preliminary Proposals x x

Present f inal proposals x x

Baseline proposal selected x

Proposal draft completed x x x x x x

1st letter ballot completed x

Resolution of comments completed x x x

Re-circulation completed x

Resolve re-circulation comments x

2nd re-circulation x

Resolve 2nd re-circulation comments. x

3rd re-circulation x

Resolve 3rd re-circulation comments. x

Sponsor ballot period x

Sponsor ballot comment resolution. x x x

Re-circulation completed x x

RevCom Approval x

2004 2005 2006 2007

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TG4a

TG4a Working Groups

• UWB-PHY (P. Rouzet – ST) P. Orlik (MERL)/I. Lakkis (Novowave)• CSS-PHY (J. Lampe – Nanotron)• Sub-GHz (P. Houghton – AetherWire)• Ranging (V. Brethour – Time Domain)• Channel Modeling (A. Molisch – MERL)• MAC (J. Bain – Fearn Consulting )

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UWB-PHY Sub-groups

• Bandplan TSE: Saeid Safavi • Pulse modulation TSE: Phil Orlik• Pulse compression TSE: Ismail Lakkis• Simulation TSE: Matt Wellborn• Sub-GHz UWB-PHY TSE: Mark Jamtgaard• Liaison to IEEE 802.19 Patricia Martigne

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UWB-PHY: Introduction• Impulse-radio based (pulse-shape

independent)• Support for different receiver

architectures (coherent/non-coherent)• Flexible modulation format• Support for multiple rates• Support for SOP (simultaneously

operating piconets)

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Operating Frequency Range(Band-Plan)

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Band-Plan• The UWB-PHY operates in the frequency

range from 3211–4693 MHz (LFB) and, optionally, from 5931.9-10304.25 MHz (HFB)

• LFB: A compliant device shall be capable of transmitting in the mandatory channel #2 (*) with a 3dB-bandwidth of 494MHz

• HFB: Transmission in all other frequency band is optional If transmission in HFB is desired then a transmitter

shall be capable of transmitting in channel #8 (*)

(*) See next slide for channels assignment

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Channels AssignmentChannel Number

Center frequency (MHz)

Band Width (3dB)

Mandatory/Optional

1 3458 494 Optional

2 3952 494 Mandatory

3 4446 494 Optional

4 3952 1482 Optional

5 6337.5 507 Optional

6 7098 507 Optional

7 7605 507 Optional

8 8112 507 Optional (Mandatory in High Band)

9 8619 507 Optional



12 10140 507 Optional

13 6591 1318.2 Optional

14 8112 1352 Optional

15 8961.75 1342.5 Optional

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LFB Band-Plan

Band Number

3 dB BW(MHz)

Low Freq.(MHz)

Center Freq.(MHz)

High Freq.(MHz)

1 494 3211 3458 37052 (mandatory) 494 3705 3952 4199

3 494 4199 4446 46934 1482 3211 3952 4693

2 321

3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00

fGHz

111 MHz 207 MHz4

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TG4a

HFB Band-PlanBand

Number3 dB BW

(MHz)Low Freq.

(MHz)Center Freq.

(MHz)High Freq.

(MHz)

5 507 6337.5 6591 6844.5

6 507 6844.5 7098 7351.5

7 507 7351.5 7605 7858.5

8 (mandatory) 507 7858.5 8112 8365.5

9 507 8365.5 8619 8872.5

10 507 8872.5 9126 9379.5

11 507 9379.5 9633 9886.5

12 507 9886.5 10140 10393.5

13 1318.2 5931.9 6591 7250.1

14 1352 7436 8112 8788

15 1342.5 8961.75 9633 10304.25

4 449 108 12116 75

6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00 9.25 9.50 9.75 10.00 10.25 10.50 10.75 fGHz

PSD

dBm

/MH

z

-41.3

-70

1413 15

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LFB: PLL Reference DiagramXTAL Oscillator

ReferenceDivider

÷ RPhase

Detector LPF VCO

÷ N

fcompfX

÷ M

fc

fs = 494 MHz

Fc fX fcomp R N M3458 MHz 13 MHz 0.40625 MHz 32 7 12163952 MHz 13 MHz 0.40625 MHz 32 8 12164446 MHz 13 MHz 0.40625 MHz 32 9 12163458 MHz 9.6 MHz 0.40000 MHz 24 7 12353952 MHz 9.6 MHz 0.40000 MHz 24 8 12354446 MHz 9.6 MHz 0.40000 MHz 24 9 1235

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Band fc fX Fcomp (MHz) R N M

HighBand

7605 MHz 13 MHz 0.40625 MHz 32 15 12488112 MHz 13 MHz 0.40625 MHz 32 16 12488619 MHz 13 MHz 0.40625 MHz 32 17 1248

2 x LowBand

6916 MHz 13 MHz 0.40625 MHz 32 14 12487904 MHz 13 MHz 0.40625 MHz 32 16 12488892 MHz 13 MHz 0.40625 MHz 32 18 1248

fc, low band

OscillatorReference

Divider÷ R

PhaseDetector LPF VCO

÷ N

XTALfcompfX

÷ M

fc, high band

fs = 507 MHz

÷ 2fs = 1352 MHz via ÷ 3

HFB: PLL Reference Diagram

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HFB: Remarks • Use of the “free spectrums” of both Japan and EU (OFCOM)• Integer product relationship between center frequencies and

PRF• Harmonization with the accepted low frequency band plan

(Use of the same PRF)• A single PLL can generate all necessary frequencies using

direct synthesis• The supported PRFs range from 507 MHz to 3.9609375

MHz through simple division by a power of 2:

÷ 2507MHz 253.5MHz

÷ 1615.84375MHz

÷ 27.921875MHz

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Data Rates

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Data Rates

Data Rate (Mb/s) Mandatory/Optional (M/O)

0.1 O

0.811 M

3.24 O

6.49 O

12.97 O

26.03 O

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Optional: ~100 kb/s Data Rate

Data Rate

(Mb/s)

Tburst Tsymbol Mean PRF

#active pulses

per burst

Viterbi(same)

RS(same)

0.811 ~32ns ~1.04us ~15.44 16 Y Y

0.101 ~256ns ~8.29us ~15.44 128 Y Y

0.811 ~8ns ~1.04us ~3.86 4 Y Y

0.101 ~64s ~8.29us ~3.86 32 Y Y

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Ranging/Acquisition Preamble

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Preamble Symbol

• The preamble field is used by the transceiver for:– Acquisition: to obtain chip and symbol

synchronization with an incoming message – Ranging: to acquire/track signal leading

edge

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Preamble Length• The adopted preamble lengths (symbols) are 64,

256, 1024, 4096:

+ Optional (short) length-16 preamble for improved energy efficiency in high data-rate communications

Code Length Preamble Index

Mandatory/Optional

Mean PRF (MHz)

Preamble Length

Duration

31 1 M 15.875 64 symbols 124.976 uS

31 2 M 15.875 256 symbols 500 uS

31 3 M 15.875 1024 symbols 2 mS

31 4 M 3.96875 64 symbols 500 uS

31 5 M 3.96875 256 symbols 2 mS

31 6 M 3.96875 1024 symbols 7.998 mS

127 7 O 127.48 64 symbols 32.907 uS

127 8 O 127.48 256 symbols 131.627 uS

127 9 O 127.48 1024 symbols 526.51 uS

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Preamble Codes: Length-31• PBTS (Perfect Balanced Ternary Sequences) are adopted as

ranging/acquisition codes, Si

• The code can be selected from length-31 or length-127 PTBS • Length-31 ternary codes:

• Note: These are the six codes with the best cross-correlation of the 12 possible codes with perfect periodic auto-correlation

Index ID Sequence

1 S1 +0++000−+−++00++0+00−0000−0+0−−

2 S2 +−0+0+00+000+0++−−−0−+00−++0000

3 S3 000+−00−00−++++0+−+000+0−0++0−0

4 S4 0+0000−00−0+−00+++−+000−+0+++0−

5 S5 +0+−0+0+000−++0−+−−−00+00++0000

6 S6 000+00−0−0++0000−−+00−+0++−++0+

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Preamble Codes: Length-127• Length-127 ternary codes:

• Note: These are the 26 codes with perfect periodic autocorrelation and best cross-correlation properties

Index ID Sequence

1 S700000-0-0+0+-0+00-00-0+00--++00-000-+0-0-0000+++++++0+-+0++0-+--0+000+0+-00-0++-+-000+000000-+00-+0-+000+--00+++0-0+--0000-00++

2 S8-0++0-+00-00-000+-+0000-0++-++00+0+0+--00+-0-000-00-+-+000-0+0000--00000-000000+++-++-0+0+0-00-+00+++0--+0+00-0++000++0+++-0--0

3 S9+0-000+-++-+-00-000000-0-+00000-++0-0000+00-+-000--0-00+00-0+-+0++0-++00++0+-00-0+0++0-0++++-0++--0000--000+000+0+00--00-+++0+0

4 S100+-0++0+000+--+-0000++-000+0+00++000000++0-0--+0-00+0-0+0++0+--00+0000+000+00-00+-++0-0+00000-0-+-+00---0----+++0+-00+0-+000-+0

5 S110+--+000-+-0---0+0-+-+0+00+0+-00+0-00+++00-000++000+0+++0000-0000-+0+00000+--+-0++000000-0+0-+0----+--00++0+-0+0-0+000+00-00++0

6 S12-+000000++0-0+--0+00-0-0+0++0+++00+0000-000+00-00--++0+0+00000-0-+++00--+0-+--+--0-+00-0+-000--00++0-+0+000+-+-+0000+++000-0+00

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Auto-correlation & Cross-correlation (L = 31)

0 5 10 15 20 25 300

5

10

15

Coherent Receiver: Periodic Autocorrelation Function

0 5 10 15 20 25 300

5

10

15

Non-Coherent Receiver: Periodic Autocorrelation Function

0 10 20 30 40-4

-2

0

2

4Non-Coherent Receiver: Periodic Cross-correlation Function

0 10 20 30 40-4

-2

0

2

4Coherent Receiver: Periodic Cross-correlation Function

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Preamble Structure

• Two forms of preamble are supported: (a) Normal preamble (b) Preamble for ~100 kb/s

Preamble Header Payload

Si Si Si

SYNCSYNC/CE SFD

Si Si

Si Si SiSi Si

-Si 0 -Si 0

-Si -Si 0 0

-Si 0 - Si 0

-Si -Si 0 0

or

Si

Si

(a)

(b)

• SYNC: Synchronization Field • SFD: Start Frame Delimiter Field• CE: Channel Estimation Field

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Preamble Parameters (L=31)

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Preamble Parameters (L=127)

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Definitions

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1 2 3 N

Active time

……………………….................

Quiet time

4 5 6 7 8 N-1

Non-inverted pulses are blue,Inverted pulses are green.

PRF DefinitionPulse Repetition Interval

Symbol Interval

…………………………

……………

Pulse Width, Tc~ 4ns @ 500MHz BW

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Pulse Repetition Frequency

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Minimum PRF RequirementsBW ~ 500 MHz

Technology CMOS 90nm 1.0 Vpp CMOS 90nm 1.0 VppTChip (nsec) 2 2Sequence Bipolar Ternary (equal ±1 & 0)VPeak (v) 0.5 0.5PAve (dBm) -14.3 -14.3PPeak (dBm) 3.8 3.8PRF (MHz) @ VPeak ~7.8 ~15.6

BW ~ 1500 MHz Technology CMOS 90nm 1.0 Vpp CMOS 90nm 1.0 VppTChip (nsec) 0.66 0.66BW (MHz) Bipolar Ternary (equal ±1 & 0)VPeak (v) 0.5 0.5PAve (dBm) -9.6 -9.6PPeak (dBm) 4.4 4.4PRF (MHz) @ VPeak ~62 ~124

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PRF: Preamble & Data Harmonization

Average Preamble PRF ~ 16 MHz (actually 494/31) every 1uS, 16 pulses

Average Data PRF ~ 16 MHz1uS 16 pulses

This maintains same pulse amplitude for Preamble and Data!

Peak Preamble PRF = ~ 31 MHz (actually 494/16)

Peak Preamble PRF = 494 MHz

Preamble Data

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Modulation

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Baseline Modulation

• Simple, scalable modulation format• One mandatory mode plus one or more

optional modulation modes• Modulation compatible with multiple

coherent/non-coherent receiver schemes Flexibility for system designer

• Time hopping (TH) to achieve multiple access

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Modulation Format• The UWB-PHY is required to support both

coherent and non-coherent receivers • The modulation format is a combination of

Pulse Position Modulation (PPM) and Binary Phase Shift Keying (BPSK)

• A UWB PHY symbol is capable of carrying two bits of information: one bit is used to determine the position of a burst of pulses while an additional bit is used to modulate the phase (polarity) of this same burst

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Chip Rate• The UWB-PHY uses an IR-based signaling

scheme in which each information-bearing symbol is represented by a sequence/burst of short time duration pluses

• The duration of an individual pulse is nominally considered to be the length of a chip

• Chip duration is equal to 2.02429 ns or a chipping rate of 494MHz

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Modulation

symbol duration

PPI

burst

COH.

NON COH.

00

0 -

01

0 -

10

1 -

11

1 -

0 1 31 32 33 6315 16 47 48

S

-S

0 1 31 32 33 6315 16 47 48

0 1 31 32 33 6315 16 47 48

0 1 31 32 33 6315 16 47 48

S

-S

PPM bit (seen by coherent and non coherent receiver)

BPSK bit (seen by coherent receiver only)

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Symbol Structure

symbol duration

1 chip ~ 2 ns

S = +--+-++-

burst duration

S=

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Reference Modulator

Note: “Input Data” is after FEC coding

SystematicEncoder

ScramblerSpreader

Ctrl LogicPosition/

Systematic bit

Polarity/Parity bit Burst

Generator

Input Data Output Data

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Receiver Architecture

BPF LNA ( )2 ADC

Scramblerdespreader

LPF

D1

Correlator

+Convolutional

Decoder

Correlator

Correlator

D2 Dm

BPF LNA IQDemod ADCLPF

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Modulation Parameters• Mandatory data rate:

• Optional data rates @PRF=15.94 MHz

• Optional data rates @PRF=3.98 MHz

Average PRF (MHz) Chip Duration (Tc) ns (TPPM) ns (Tburst) ns

15.4375 2.02429 502 32.4

3.859375 2.02429 502

Data Rate (Mbps) Chip Duration (Tc) ns (TPPM) ns (Tburst) ns

0.1 2.02429 4.016 259

3.24 2.02429 0.126 8.1

12.97 2.02429 0.031 2.02

Data Rate (Mbps) Chip Duration (Tc) ns (TPPM) ns (Tburst) ns

0.1 2.02429 4.016 64.8

3.24 2.02429 0.126 2.02

6.49 2.02429 0.063 1.01

12.97 2.02429 0.031 0.51

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Spreading

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Spreading• In addition to the data modulation, the UWB-PHY

symbol provides for some multi-user access interference rejection in the form of TH

• Each symbol contains a single burst of pulses and the burst length is typically much shorter than the duration of the symbol

• The location of the pulse within each burst can be varied on a symbol-to-symbol basis according to a TH code

• This is part of the functionality provided by the “Scrambler and Burst Position Hopping”

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Scrambling• The constituent pulses in each burst are scrambled by

applying a time varying scrambling sequence • This scrambler is a pseudo-random binary sequence

(PRBS) defined by a polynomial generator. • The polynomial generator, g(D), for the pseudo-random

binary sequence (PRBS) generator is g(D) = 1 + D14 + D15, where D is a single bit delay element.

• The polynomial not only forms a maximal length sequence, but is also a primitive polynomial. Using this generator polynomial, the corresponding PRBS, sj, is generated as

where “” denotes modulo-2 addition ,...2,1,0,1514 jsss jjj

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Scrambler• Scrambler linear feedback shift register:

Dsj-1

Scrambler output sn

Dsj

sj-15

sj-2D

sj-3D

sj-13D

sj-14 sj-15

Hopping position address

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Time Hopping• The hopping sequence is derived from the same linear

feedback shift registers by using the output of the first three registers

• When each symbol, x(k)(t), is generated, the spreader is run for Nburst cycles the Nburst consecutive outputs of the spreader are the spreading sequence for the symbol (sj, j = 1,2, …, Nburst)

• The current hopping position, h(k) is determined by the following equation:

• The state variables are sampled at the start of the transmission of the current modulation symbol

22

11

0)( 222 jjjk sssh

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Spreading COH.

NON COH.

00

0 -

01

0 -

10

1 -

11

1 -

0 1 31 32 33 6315 16 47 48

S SSSS

possible positions obtained through

scrambling

-S -S -S -S -S

0 1 31 32 33 6315 16 47 48

0 1 31 32 33 6315 16 47 48

0 1 31 32 33 6315 16 47 48

S SSS

-S -S -S -S

Guard time for channel delay

spread (260ns)

Note: S value is also changed at each symbol

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FEC

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FEC• The FEC used by the UWB PHY is a concatenated code

consiting of an outer Reed-Solomon (RS) systematic block code and an inner systematic convolutional code

• No interleaver is required• The outer RS code is a RS6(K+8,K) over Galois field GF(26)• The systematic Reed Solomon code uses the generator

polynomial:

where a= 010000 is a root of the binary primitive polynomial

1+x+x6 in GF(26)• Both RS encoding with default codeword operation (K = 55)

and shortened codeword operation are required

7

0

)(k

kaxxg

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Modulation & Coding –Mandatory Data Rate

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UWB-PHY Symbol• The UWB-PHY supports two average Pulse

Repetition Frequencies (PRF):– HPRF=15.4375MHz– LPRF=3.859375MHz

• These PRFs in addition to the data rate, modulation and coding rate determines the overall timing of a UWB-PHY symbol

Avg. PRF (MHz)

Chip Rate (MHz)

Modulation Order (bits/Symbol)

Data Rate (Mbps)

FEC rate (outer code)

FEC rate (inner code)

Code rate

Symbol Rate (MHz)

Pulses per Burst (Nburst)

Burst Duration (ns)

# of slots (Ns)

15.4375 494 2 1 1/2 .88 .44 0.996 16 32.4 31

3.859375 494 2 1 1/2 .88 .44 0.996 4 8.1 124

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Symbol Mapping• The UWB-PHY map groups two consecutive bits into

modulation symbols, as follows:

Information Bits (b1b0)

Modulation Symbols (g1g0)

00 -10

01 -11

10 10

11 11

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Predetermined position scrambler to improve SOP

Common Data Protocol : Coherent/Non-CoherentPRFPeak

0s

494

0 0 0 0 0 0 0 0 0 0

0 = 0000000000000000s = +--+-+---+-+++-+16 pulses/slot

32.4 ns

00

00

01

01

-s

10

10

11

11

0

0

0

0

1

1

1

1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 s0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

-s0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 s0 0 0 00 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 s0 0 0 00 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0

0 0 0 0 00 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0-s

0 0 0 0 00 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0-s

Tsymbol = 1036.44 ns

MbpsT

tRateNonCoherenMbpsT

teCoherentRa

MHzMHzPRFnsTT

nsTTnsMHz

T

symbolsymbol

avgslotsymbol

cslotc

965.0193.12

4375.1532

49444.103632

4.32160243.2494

1

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

FEC

position

d

sign

K = 3, R = ½ g1 = [010], g2 = [101]

Reed Solomon

Primitive polynomial:

Generator polynomial:

61 xx

7

0i

ixxg

SystematicRS(51,43,8)R = 0.843

Non-Coherent Receiver sees this bit only

1.93 Mbps

0.811 MspsN: 0.811 MbpsC: 0.811 Mbps

position (systematic bit)

sign (parity bit)

Modulator1 or 2bits/

symbol

Non-Coherent : Rate 0.843 Coherent: Rate 0.422

N: 258 bitsC: 258 bits


N: 307 symbols (1b/s)C: 307 symbols (2b/s)

Systematic Convolutional

EncoderK = 3, R = 1/2


Non-Coherent Receiver uses this only

1.63 Mbps307b

307b0.965 Mbps 0.81 Mbps

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

FEC: Soft DecisionsParity / Data

[p d] Tx Signal Rx Signal[x1 x2]

Correlator Ouput

0s

0-s

0 s

0 -s

0 0

1 0

0 1

1 1

w2s + w1

w2-s + w1

w1

w1

s + w2

-s + w2

C1 = +x1.sH

C2 = -x1.sH

C3 = +x2.sH

C4 = -x2.sH

soft_bit(p) = max(C1,C3) - max(C2,C4) = C1 + C3 soft_bit(d) = max(C1,C2) - max(C3,C4) = |C1| - |C3|

Soft decision rule:soft_bit(bit) = max(Ck’s where bit is 0) - max(Ck’s where bit is 1)

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Modulation & Coding–Optional Data Rates

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

UWB-PHY Symbol• The additional data rates require that the # of pulses/burst are modified;

this in turn alters the burst duration and other symbol parameters:

Data Rate (Mbps)

Symbol Duration (us)


Burst Duration (ns)

# of slots (Ns)

0.1 8.0324 128 259 31

3.24 0.251 4 8.1 31

12.97 0.0628 1 2.02 31

Data Rate (Mbps)

Symbol Duration (us)


Burst Duration (ns)

# of slots (Ns)

0.1 8.0324 32 64.8 124

3.24 0.251 1 2.02 124

12.97 0.0628 1/4 0.51 124

HPRF = 15.94 MHz

LPRF = 3.98 MHz

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Modulation Format

Predetermined chip level position scrambler to improve SOP

Common Data Protocol : Coherent/Non-CoherentPRFPeak

494

s0 = 0000000000000000

s = 1000000000000000 ors = 0100000000000000 or ...s = 0000000100000000

1 active pulse per slot

32.4 ns00

01

10

11

Tsymbol = 64.8 ns

MbpsT

tRateNonCoherenMbpsT

teCoherentRa

MHzMHzPRFnsTT

nsTTnsMHz

T

symbolsymbol

avgslotsymbol

cslotc

4375.151875.302

4375.1532

4948.642

4.32160243.2494

1

s

0

0

-s

-s

0

0

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

FEC

SystematicRS(51,43,8)R = 0.843

Non-Coherent Receiver sees this bit only

30.875 Mbps

N: 12.97 MbpsC: 12.97 Mbps

position (systematic bit)

sign (parity bit)

Modulator1 or 2bits/

symbol

Non-Coherent : Rate 0.843 Coherent: Rate 0.422



N: 307 symbols (1b/s)C: 307 symbols (2b/s)

Systematic Convolutional

EncoderK = 3, R = 1/2


Non-Coherent Receiver uses this only

26.03 Mbps307b

307b15.4375 Mbps 13.016 Mbps

position

d

sign

K = 3, R = ½ g1 = [010], g2 = [101]

Reed Solomon

Primitive polynomial:

Generator polynomial:

61 xx

7

0i

ixxg

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Modulation & Coding OptionsData Rate

(MHz)

Commonmode

Tslot Tsymbol #active pulses per slot

Viterbi RS

26.03 N 32.4 ns 64.8ns 1 N Y

12.97 Y 32.4 ns 64.8ns 1 Y Y

6.49 Y 32.4 ns 64.8ns 2 Y Y

3.24 Y 32.4 ns 64.8ns 4 Y Y

1.62 Y 32.4 ns 64.8ns 8 Y Y

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Waveforms

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Pulse Shaping

• The reference pulse, r(t), used by the UWB-PHY is a root raised cosine pulse with roll-off factor of = 0.6• Mathematically this is:

• In order for a UWB-PHY transmitter to be compliant with the standard, the transmitted pulse must have a cross- correlation with r(t) that is greater or equal to 0.7 (-3dB)

221

cossin)(

c

c

c TtTt

Ttctr

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Optional Wafeforms

1. Weighted linear combination of pulses2. Chirp pulses (CoU)3. Continuous Spectrum (CS) pulses4. Chaotic pulses

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Weighted Linear Pulses-Combination

• This optional pulse shape is the sum of N weighted and delayed “fundamental” pulses, p(t):

• The number of pulses N is set to a fixed value of 4 (although some of the weights may be set to zero)

• The values of the pulse delays shall be limited• Features:

– Adaptive determination of weight and delay– Adaptive spectral shaping– Can adjust to interferers at different distances (required

nulldepth) and frequencies

)()(1

i

N

ii tpatp

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Chirp on UWB (1/2)

• Additional dimension to support SOP – Chirp slopes and chirp patterns– Better performance than DS codes– Combination with FDM and/or CDM

• Additional link margins – Low peak-to-average ratio.

• Robustness against interference and multipath– Excellent correlation characteristics

• Potential high-precision ranging– Excellent correlation characteristics

time

T

time

T

Main features:

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Chirp on UWB (2/2)• Mathematical expression:

where P(t) denotes the mandatory pulse and μ=B/T the chirping rate (chirping slope); B and T are the bandwidth and time duration of the chirped pulse

• Raised cosine pulse:

otherwise

TtTtjtPtPCoU;0

22;

2exp)()(

2

221

1;

2;1

2111cos1

21

211;1

)( TtT

Tt

TtT

Tt

tP

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Block Diagram With Optional CS

modulation Spreading

Pre-SelectFilter

LNA

Transmitter

Receiver

Pulseshaping GA

Local oscillator

BW = 494 MHz

Additional circuits to DS-UWB as an option

LPF

LPF

GA

GA

1 to 2-bit ADC

1 to 2-bitADC

Sync.Local

oscillator

De-spreadingDecision/

FEC decoder

I

Q

FEC

DCHIRP

DE-CHIRP

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

CS Pulse (1/2)

Gaussian without CS1ns/1GHz CS5ns/1GHz CS10ns/1GHz CS

dfftfjfGtg cs )(2exp)()(

• Mathematical expression:

where (f) is the group delay and:

Examples:

dtftjtgfG )2exp()()(

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

CS Pulse (2/2)

• Main features:– SOP support: CS filtering provides additional anti-interference

ability (additionally larger SIR) w.r.t. DS

Interference scenarios: CS CS: Piconets with different CS filtering can reduce the interference

against each other DS CS: Piconet with CS filtering can reduce the interference from DS-

only piconets CS DS: DS-only piconet receivers smaller interference from piconets

with CS filtering

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

Chaotic Pulse

VPeak

TC

PRI

Ts Ts =~ 30 nsec.

ChaoticOption 1Unipolar

Ts

Ts =~ 2 nsec. => Chip duration ≈ 2 ns (2.024291 ns)

-PRF of Chaotic pulse length(Ts) can be changed flexibly without altering the spectral shape or Band Plan

TG4aDraft

Ts

ChaoticOption 2Ternary

Bit 1 => Ref & (+Ref)

Ts =~ 30 nsec.

Bit 0 => 0 Bit -1 => Ref & (-Ref)

Bit 1 Bit 0 => 0 Bit -1 => Bit 1

November 30, 2005


Doc.: IEEE 15-05-0707-01-004a

TG4a

PreambleTernaryScrambler

S/WChaotic

Impulse

DataFECScrambler

MUXPreambleData

BPSK .MOD

4.5 GHzLO

RFS/W

RFS/W

BPSK .DEMOD

Chaotic Detector

Code1Cross Correlator

Code2Cross Correlator

Block Diagram With Chaos Option

Non-coherentDetector

S/W

S/W

Decision LPF

Doc.: IEEE 15-05-0707-01-004a TG4a November 30, 2005 Gian Mario Maggio (ST)Slide 1 Project: IEEE...

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Transcript of Doc.: IEEE 15-05-0707-01-004a TG4a November 30, 2005 Gian Mario Maggio (ST)Slide 1 Project: IEEE...