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

04/19/23

Ismail Lakkis & Saeid SafaviWideband Access, Inc.

1TG4a

Doc: IEEE 15-05-0250-01

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: [Revised Frequency Plan and PRF Proposal for TG4a]Date Submitted: [27 April 2005]Source: [Ismail Lakkis & Saeid Safavi, Wideband Access Inc.]Contact: Saeid Safavi.Voice:[+1 858 642 9114, E-Mail: [email protected]]Abstract: [Ban Plan, PRF, Preamble & Modulation]Purpose: [Clarification of relationship between minimum PRF and maximum allowed voltage level in UWB IR]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.

04/19/23


2TG4a

Doc: IEEE 15-05-0250-01

Agenda

• Proposed system features• Frequency Plan / PRF• Preamble • Modulation

04/19/23


3TG4a

Doc: IEEE 15-05-0250-01

Frequency Plan / PRF

04/19/23


4TG4a

Doc: IEEE 15-05-0250-01

Proposed System Features• Meets requirements for TG4a baseline draft• Frequency plan with simple PLL structure and safe

margins to 3.1GHz and 4.9 GHz• Support of a range of PRFs (low and high)• Impulse-radio system• Common preamble structure for different classes of

nodes/receivers type ( coh./noncoh.) & ranging• Flexible adaptive data rate• Robustness against SOP interference through frequency

and code division• Robustness against other in-band interference• Scalability to trade-off complexity/performance

04/19/23


5TG4a

Doc: IEEE 15-05-0250-01

Frequency Plan Requirements• Requirements

– Sub-banding (Three bands) with mandatory center band of ~500MHz and an optional wider co-centric band of ~1.5GHz

– Mandatory: FCC spectral mask @ 3.1GHz at least 10 dB attenuation constraint on filtering

– Desirable: co-existence with WLAN @ 4.9GHz

• Implications– A safe margin to 3.1GHz to meet FCC requirement– For IR system using a pulser (no mixer), the BPF is responsible

for the 3.1GHz corner filtering– A safe margin to 4.9GHz to coexist with WLAN– Different frequencies should be easily generated from the

system PLL with first divisions in powers of 2

04/19/23


6TG4a

Doc: IEEE 15-05-0250-01

PRF Requirements• Requirements

– Support of multiple (at least 2) PRF in band– Limit on lowest possible PRF due to CMOS 90 nm technology– Limit on highest possible PRF due to inter-frame interference for

a non-coherent receiver

• Implications– Supported PRFs should be easily derived from the PLL through

simple divisions– Low PRF as base PRF – High PRF as second PRF– PRF should be high enough to take advantage of FCC rules

04/19/23


7TG4a

Doc: IEEE 15-05-0250-01

Relationship between PRF & Peak Power

VPeak

TC

PRI

))((log103.41)(

where

,10

)(log10)(log10)()(

or

ModulationBPSK

10

10

)()(log10)(

1010

10

MHzBWdbmP

PRF

PRFBWdbmPdbmP

PRF

BWPP

Ave

dbmPBWdbmP

MHzMHzAvePeak

AvePeak

PeakPeakAve

))((log103.41)(

where

,10

)(3)(log10)(log10)()(

or

2

ModulationTernary

10

10

3)()(log10)(

1010

10

MHzBWdbmP

PRF

dBPRFBWdbmPdbmP

PRF

BWPP

Ave

dbmPBWdbmP

MHzMHzAvePeak

AvePeak

PeakPeakAve

04/19/23


8TG4a

Doc: IEEE 15-05-0250-01

Minimum PRF vs Peak Power (CMOS 90nm)BW = 500 MHz

Technology CMOS 90nm 2.5 Vpp, BPSK CMOS 90nm 2.5 Vpp, Ternary

TChip (nsec) 2 2

BW (MHz) 500 500

VPeak (v) 1.25 1.25

PAve (dBm) -14.31 -14.31

PPeak (dBm) 11.94 11.94

PRF (MHz) @ VPeak (No Margin) 1.19 2.37

PRF (MHz) @ VPeak (8 dB Margin)* 7.48 14.97

BW = 1500 MHz

Technology CMOS 90nm 2.5 Vpp, BPSK CMOS 90nm 2.5 Vpp, Ternary

TChip (nsec) 0.66 0.66

BW (MHz) 1500 1500

VPeak (v) 1.25 1.25

PAve (dBm) -9.54 -9.45

PPeak (dBm) 11.94 11.94

PRF (MHz) @ VPeak (No Margin) 10.67 21.35

PRF (MHz) @ VPeak (4.5 dB Margin) 30.09 60.17

04/19/23


9TG4a

Doc: IEEE 15-05-0250-01

Low PRF vs High PRF

• A low PRF system has a lower implementation cost when compared to high PRF system

• RF radio overall gain is lower for a low PRF system. A 12 MHz PRF system , for example, would reduce the receiver dynamic range by 7 dB when compared to a 60 MHz PRF system

• The ADC would run at 12 MHz instead of 60 MHz in the above example and the entire digital processor would run at a lower clock reducing the power by a factor of 5 in CMOS

• Easier acquisition with lower PRF due to a smaller sync matched filter size

• Since energy per pulse is higher (7 dB in the above example), a non-coherent receiver would perform better

• Better acquisition and tracking performance since a 60 MHz PRF system needs to integrate perfectly 5 pulses to perform equivalently to a 12 MHz PRF system

04/19/23


10TG4a

Doc: IEEE 15-05-0250-01

Proposed Frequency PlanBand No. 3 dB BW

(MHz)

Low Freq.

(MHz)

Center Freq.

(MHz)

High Freq.

(MHz)

1 494 3211 3458 3705

2 494 3705 3952 4199

3 494 4199 4446 4693

4 1482 3211 3952 4693

3 4 5 GHz3.5 4.53.25 3.75 4.25 4.75

Note: This plan has almost double margin to 4.9 GHz as compared to 3.1 GHz

1 2 3

Band No. 4

207MHz

111MHz

04/19/23


11TG4a

Doc: IEEE 15-05-0250-01

Frequency Plan Details New Band Plan

(in MHz)

XTAL 26

R 8

Fref 3.25

DF 494

F2C 3952 F2L 3705 F2H 4199

F1C 3458 F1L 3211 F1H 3705

F3C 4446 F3L 4199 F3H 4693

PRF1 61.75

N1 64 N2 56 N3 72

PRF2 30.875

N1 128 N2 112 N3 144

PRF3 15.4375

N1 224 N2 256 N3 288

MHzBW

MHzDF

where

PRFMNF

PRFMNF

PRFNF

PRFMDF

dB

mmC

mmL

mmC

500

494

)(

,)(

,

,

:Note

10

04/19/23


12TG4a

Doc: IEEE 15-05-0250-01

Proposed PRFs• A wide range of PRFs (total of 3) are supported which are

compliant with the harmonic chip rate requirements

• The base recommended PRF is 15.4375 MHz: it has an 8 dB peak power margin for a 500MHz BW

• PRFs of 30.875MHz and 61.75MHz are also supported (margin > 4.5 dB)

• The proposed PRFs can be easily generated from the center frequencies of the supported bands (next slide)

04/19/23


13TG4a

Doc: IEEE 15-05-0250-01

PRF Generation

64

8x7

8x3x3

Center Freq.(MHz)

Harmonic RatioPRF1 (MHz)

3952

3458

4446

61.75

Prime Factors: 7, 3

2 230.875

61.752 2

61.752 2

30.875

30.875

15.4375

15.4375

15.4375

• All High frequency divisions are in powers of 2, while the low frequency divisions are only by 3 and 7

PRF2(MHz)

PRF3(MHz)

04/19/23


14TG4a

Doc: IEEE 15-05-0250-01

PLL Reference Diagram

OscillatorReference

Divider(R)

Divider, M

Phase Det.

XTAL

FX FComp

LPF VCO

F123,c

FX (MHZ) R Fcomp (MHz)

(13,26) (4,8) 0.8125

(9.6,19.2) (24,48) 0.4

(12,24) (6,12) 2

÷8

÷ 7,8 or 9

PRF

04/19/23


15TG4a

Doc: IEEE 15-05-0250-01

Band Plan / PRF Summary• Enough margin to 3.1GHz (111 MHz) and 4.9GHz (207

MHz) to meet FCC requirements and to coexist with WLAN ( avoids expensive sharp roll-off filtering)

• Support of a wide range of XTALs (9.6,19.2,13,26,12,24)

• Center frequencies and PRFs can be generated from a single PLL with first divisions in power of 2 and low frequency division by 3 or 7

• Support of a wide range of PRFs. The proposed PRFs have a peak power margin of 4.5-8 dB to accommodate implementation losses and take advantage of FCC rules

04/19/23


16TG4a

Doc: IEEE 15-05-0250-01

Acquisition Preamble Structure

04/19/23


17TG4a

Doc: IEEE 15-05-0250-01

BER of BPSK & ON-OFF Keying

0 2 4 6 8 10 12 14 16 1810

-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

ON-OFF Keying BER

EBN0dB

BE

R

BPSK

ON-OFF

(dB) ON-OFF

BER

Opt.

Thres.

10 2.7e-2 2.72

11 1.3e-2 2.96

12 5.7e-3 3.24

13 1.94e-3 3.55

14 5.06e-4 3.91

15 9.47e-5 4.31

16 1.16e-5 4.77

04/19/23


18TG4a

Doc: IEEE 15-05-0250-01

BER Requirements• The requirement of PER < 1% for a 32 octets packet

translates into a BER < 3.926e-5

• EbN0 requirements for uncoded BPSK and ON-OFF keying systems:– (BPSK) = 8.9dB– (ON-OFF) = 15.45dB

• EbN0 requirements for coded BPSK and ON-OFF keying systems (assuming a coding gain of 4dB and receiver implementation losses of 1.5 dB):– (BPSK) = 6.4 dB– (ON-OFF) = 13 dB

04/19/23


19TG4a

Doc: IEEE 15-05-0250-01

SNR Loss in Square Law Detectors

-15 -10 -5 0 5 10 153

4

5

6

7

8

9

10

11

12

13

SNRdB

@ Square Law Detector Input

SN

R-L

oss dB

SNR Loss due to square law detector

PRF 32 MHz 32 MHz

EbN0 13 dB 13 dB

Data Rate 2Mbps 100 kHz

EsNo 1 dB -12 dB

SNRLoss 4dB 10 dB

04/19/23


20TG4a

Doc: IEEE 15-05-0250-01

BPSK: Detection & False Alarm Probabilities

Data Rate2

Mbps

1

Mbps

500

Kbps

250

Kbps

125

Kbps

62.5

Kbps

32.25

Kbps

EpN0(dB) -2.5 -5.5 -8.5 -11.6 -14.6 -17.6 -20.6

Nc 32 32 32 32 32 32 32

L 1 2 4 12 36 112 448

Nc 256 256 256 256 256 256 256

L 1 1 1 1 2 4 12

• PRF = 16 MHz• AWGN Channel • 2 dB margin to account for timing/frequency errors & other factors• PD = 95% & PF = 5%

04/19/23


21TG4a

Doc: IEEE 15-05-0250-01


Data Rate2

Mbps

1

Mbps

500

Kbps

250

Kbps

125

Kbps

62.5

Kbps

32.25

Kbps

EpN0(dB) -2.5 -5.5 -8.5 -11.6 -14.6 -17.6 -20.6

Nc 32 32 32 32 32 32 32

L 4 12 36 112 448

Nc 256 256 256 256 256 256 256

L 1 1 2 4 12 36 112

• PRF = 16 MHz• Multipath Channel assuming we capture 25% of the energy• 2 dB margin to account for timing/frequency errors & other factors• PD = 95% & PF = 5%

04/19/23


22TG4a

Doc: IEEE 15-05-0250-01


0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1

False alarm probability PF

Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -5.5, Nc = 32, margin = 2dB

L = 1

L = 2

0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1


Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -8.5, Nc = 32, margin = 2dB

L = 3

L = 4

L = 5

0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1


Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -11.5, Nc = 32, margin = 2dB

L = 8L = 10L = 12L = 14

0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1


Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -14.6, Nc = 32, margin = 2dB

L = 20L = 24L = 28

L = 32L = 36L = 40

04/19/23


23TG4a

Doc: IEEE 15-05-0250-01


0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1


Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -17.6, Nc = 32, margin = 2dB

L = 64

L = 80

L = 96

L = 112

0 0.02 0.04 0.06 0.08 0.1 0.120.88

0.9

0.92

0.94

0.96

0.98

1


Det

ectio

n pr

obab

ility

PD

AWGN : EpN0dB

= -20.6, Nc = 32, margin = 2dB

L = 256L = 320L = 384L = 448L = 512

04/19/23


24TG4a

Doc: IEEE 15-05-0250-01

ON-OFF Detection & False Alarm Probabilities

Data Rate2

Mbps

1

Mbps

500

Kbps

250

Kbps

125

Kbps

62.5

Kbps

32.25

Kbps

EpN0(dB) 4 1 -2 -5 -8 -11 -14

L 32 64 96 352 1280

• PRF = 16 MHz• AWGN Channel • 2 dB margin to account for timing/frequency errors & other factors• PD = 95% & PF = 5%

04/19/23


25TG4a

Doc: IEEE 15-05-0250-01

Spreading Codes: Objectives• Design a set of sequences with good

autocorrelation (ACF) and cross correlation (CCF) properties that support – Coherent receivers– Differentially coherent receivers– Noncoherent receivers

• The sequence set should be as large as possible to support multiple piconets per frequency band and to mitigate co-channel interference (in-band interference)

04/19/23


26TG4a

Doc: IEEE 15-05-0250-01

Spreading Codes Desirable Characteristics• The autocorrelation function of a sequence can be

characterized by the following parameters:– PAR of the PSD (back-off factor): a b PAR is desirable otherwise

reduction in Tx power is required– Zero correlation zone (ZCZ) : for improved ranging,

synchronization, channel estimation, and Pd vs Pf– Merit Factor (MF) of a binary sequence of length N: The MF

measures the interference due to the sidelobe energies in the zone under interest (say 1μs)

– Sequence length: this determines the coherent processing gain during acquisition ( a short spreading sequence system is acquisition limited rather than PER limited)

n nSLL

NMF

2

2

10log10

04/19/23


27TG4a

Doc: IEEE 15-05-0250-01

Barker code 11 & m-sequence 31

-10 -5 0 5 10-2

0

2

4

6

8

10

12aperiodic autocorrelation function

-300 -200 -100 0 100 200 300-12

-10

-8

-6

-4

-2

0

2

freqMHz

Power spectral density

-0.2 -0.1 0 0.1 0.2-34

-32

-30

-28

-26

-24

-22

Frequency (kHz)

Pow

er/

frequency (

dB

/Hz)

Power Spectral Density Estimate via Welch

-30 -20 -10 0 10 20 30-10

0

10

20

30

40periodic autocorrelation function

04/19/23


28TG4a

Doc: IEEE 15-05-0250-01

Freescale & ZCZ sequences

-300 -200 -100 0 100 200 300-10

-8

-6

-4

-2

0

2

freqMHz


-30 -20 -10 0 10 20 30-5

0

5

10

15

20

25aperiodic autocorrelation function

-40 -20 0 20 40-10

0

10

20

30

40periodic autocorrelation fct

-200 -100 0 100 200-10

-5

0

5

10

15

freqMHz


04/19/23


29TG4a

Doc: IEEE 15-05-0250-01

Single Spreading Code System ?• A single spreading code common to the

preamble and frame body is not recommended as all good sequences have bad PSD which results in a large Tx power reduction (Back-off)

length ZCZ width SLL Back-Off

Barker 11 1 0 1.2 dB

m-sequence 31 NA 1 4.5 dB

Freescale 24 NA 1 2.1 dB

ZCZ 32 8 0 2.4 dB

04/19/23


30TG4a

Doc: IEEE 15-05-0250-01

Hierarchical Preamble code structure• Let Z be the ZCZ sequence of length 3• Create hierarchical code using zero-correlation Walsh sequences

1,2,3 and 5• For ternary –Z corresponds to an inverted sequence• There are at least 32 ZCZ, this gives 128 SOPs

Seq1 Z Z Z Z Z Z Z Z

Seq2 Z -Z Z -Z Z -Z Z -Z

Seq3 Z Z -Z -Z Z Z -Z -Z

Seq4 Z -Z -Z Z Z -Z -Z Z

Seq5 Z Z Z Z -Z -Z -Z -Z

Seq6 Z -Z Z -Z -Z Z -Z Z

Seq7 Z Z -Z -Z -Z -Z Z Z

Seq8 Z -Z -Z Z -Z Z Z -Z

04/19/23


31TG4a

Doc: IEEE 15-05-0250-01

modulation

04/19/23


32TG4a

Doc: IEEE 15-05-0250-01

Modulation• Spreading via random scrambling• Use a single scrambler of length (ex: 32768) and

assign a different offset (of 16 or 32) to different nodes

• For ternary modulation invert sequence when transmitting a 0

• Number of users supported is 1024• Perfect co-channel interference rejection• Support virtually any data rate from 16MHz to 32

Kbps for a PRF of 16MHz• Spectrum is virtually flat (no back-off)

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

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