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: [Staccato UWB PHY Proposal for TG4a]

Date Submitted: [January 2005]Revised: []

Source: [Roberto Aiello, Ph.D., Torbjorn Larsson, Ph.D.] Company [Staccato Communications] E-mail [[email protected]]

Re: [802.15.4a Call for proposal]

Abstract: [This presentation represents Staccato Communication’s proposal for the 802.15.4a PHY standard, based on UWB]

Purpose: [Response to WPAN-802.15.4a Call for Proposals]

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 or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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.

January 2005 doc.: IEEE 802.15-04/xxxr0

January 2005

Roberto Aiello, Staccato CommunicationsSlide 2

doc.: IEEE 802.15-04/704r0

Submission

Staccato CommunicationsUWB PHY Proposal for TG4a

Roberto Aiello, Ph.D.

Torbjorn Larsson, Ph.D.

Staccato [email protected]

January 2005


doc.: IEEE 802.15-04/704r0

Submission

Goals

• Good use of UWB unlicensed spectrum• Good system design• Path to low complexity CMOS design• Path to low power consumption• Scalable to future standards• Graceful co-existence with other services• Graceful co-existence with other UWB systems

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Submission

Introduction

• Staccato is MBOA’s founding member, promoter BOD member• This proposal is based on band limited impulse radio• OFDM is optimal solution for high performance systems• Impulse radio has attractive features for 15.4a applications

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Submission

Features

• Meet all system requirements• Low signal repetition frequency to reduce ISI and need for high

speed digital circuits (lower power consumption)• “Narrow” UWB bandwidth to reduce complexity

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Submission

Summary

• Band limited UWB system• Compliant with FCC 02-48, UWB Report & Order• 4.752GHz, 5.252GHz center frequency, 500MHz bandwidth at -10dB• Varies symbol rate, from 12.5kbps to 1.6Mbps at PHY-SAP

• Due to time constraints this presentation addresses– Modulation scheme– Performance in AWGN channel

• Remaining material will be presented at the next opportunity in March 2005– Performance in multipath– Channelization– Implementation feasibility– Self evaluation criteria– Other issues that will emerge from group’s feedback

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doc.: IEEE 802.15-04/704r0

Submission

FCC compliant

• FCC compliant according to FCC UWB R&O

• In this proposal the transmit signal occupies 500MHz at all times: frequency change is used to reduce ISI, not to spread the spectrum

• “Thus, as long as the transmission system complies with the fractional bandwidth or minimum bandwidth requirements at all times during its transmission, we agree that it should be permitted to operate under the UWB regulations.” [FCC UWB R&O, B-32]

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Submission

System description

• code length longer than 16 is required to define a reasonable number of codes with good cross-correlation properties• different piconets use different spreading codes• PRF (chip rate), 3.2 MHz is fairly high

– Disadvantages• some impact of interchip interference with channel model 8 (industrial NLOS),

– Advantages• it allows use of rate 1/2 coding at 100 kbps (we consider this one of the most important data rates)• It also allows implementation without frequency offset correction (with some performance loss)• it removes the need for frequency offset correction during acquisition, which leads to faster acquisition and a shorter preamble• After acquisition, frequency offset correction can be switched on to improve the performance• If the frequency offset estimate is good enough, it is possible to use partially coherent detection (with a coherent integration

interval equal to the spreading code duration) instead of differential detection for further improved performance.• Pulse shape: 3rd-order Butterworth• FEC: 16-state convolutional code, with optional puncturing.

Data Rate [kbps] Length of SFD in bits Length of spreading code in PHR and PSDU

12.5 32 16 25 32 16 50 32 16 100 32 16 200 16 8 400 8 4 800 5 2 1600 3 1

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doc.: IEEE 802.15-04/704r0

Submission

Packet structure

400 kbps

Preamble192 chips

SFD128 chips

PHR48 symbols

PSDU(LENGTH*8+4)*2 symbols

1 symbol = 4 chips

200 kbps

Preamble384 chips

SFD256 chips

PHR48 symbols


1 symbol = 8 chips

Preamble768 chips

SFD512 chips

PHR48 symbols


1 symbol = 16 chips

800 kbps

Preamble96 chips

SFD80 chips

PHR48 symbols


1 symbol = 2 chips

1600 kbps

Preamble48 chips

SFD48 chips

PHR48 symbols


1 symbol = 1 chip

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Submission

Spreading codes

Spreading codes of length 16 with minimal autocorrelation and cross-correlation, essential for acquisition, were found.

-1 -1 1 -1 -1 1 -1 1 -1 -1 -1 1 1 1 1 1 -1 1 -1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 1 1 -1 1 1 -1 1 -1 -1 -1 -1 -1 1 1 1 -1 1 1 -1 -1 -1 -1 -1 1 1 1 1 -1 1 1 -1 1 -1 1

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Submission

Throughput

• The length of the data PSDU (payload) is 32 octets. The data rate is 100 kbps (this is X0 in this proposal)

• Assumptions (refer to the figure on page 20 in the PHY selection criteria document)– aMinLIFSPeriod = 40 symbol periods – aTurnaroundTime = 12 symbol periods – aUnitBackoffPeriod = 20 symbol periods – Length of ACK PSDU = 5 octets

• t_ack is the time between the end of the data frame and the beginning of the ACK frame– worst case, is t_ack = aTurnaroundTime + aUnitBackoffPeriod = 32 – best case, t_ack is t_ack = aTurnaroundTime = 12

Data Rate [kbps] Worst-Case Throughput [kbps] Best-Case Throughput [kbps] 1600 875.2 894.3 800 437.6 447.2 400 218.8 223.6 200 109.4 111.8 100 54.7 55.9 50 27.4 27.9 25 13.7 14.0 12.5 6.8 7.0

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Submission

Transceiver architecture (digital)

LPFX

LOLNA/VGA

Timing

X LPF ADC

ADC

DiffDetection

MultipathCombing

DSDe-Spread

SymbolCombining

ViterbiDecoding

AcquisitionGain

LPFX

LOLNA/VGA

Timing

X LPF ADC

ADCDiff

DetectionMultipathCombing

DSDe-Spread

SymbolCombining

ViterbiDecoding

Acquisition

Non-CoherentDetection

MultipathCombining

(Across one DS codeword)

Gain

FrequencyCorrection

Data

Freq Offset

differential detection for acquisition and non-coherent demodulation for data demodulation

differential detection for both acquisition and data demodulation

A.

B.

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Submission

More on receiver

• acquisition is based on differential detection, which allows shorter preamble• both differential and non-coherent detection are carried out separately for the

different multipath components

Architecture A. • differential detection for both acquisition and data demodulation.

Architecture B.• differential detection for acquisition• non-coherent demodulation (with coherent combining across one codeword) for

data demodulation• requires frequency offset estimation (during acquisition) and correction (during

data demodulation)– differential detection without frequency offset correction. This is possible since the

maximum frequency offset is roughly 220 kHz, which leads to a phase shift of 220000/3200000*360 = 25 degrees across one chip period.

– differential detection with frequency correction (after acquisition). This will remove the 25 degrees phase shift, leading to some performance improvement.

– non-coherent demodulation (with coherent combining across one codeword), which requires frequency offset correction. This should lead to a significant performance improvement, since we are now summing energy coherently across a whole codeword (which for data rates <= 100 kbps is 16 chips long).

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Submission

Differential combining

nx ,1nx ,2

nx ,3

1,1 nx1,2 nx

1,3 nx

*,31,3

*,21,2

*,11,1 ReReRe nnnnnn xxxxxx

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Submission

Alternative analog transceiver architecture

• Minimum receiver configuration• Potential sub-optimal performance• Potential low cost and power implementation

ADC

~

Baseband Processor

MAC

Integrator

Transmitter

SRAM

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Submission

Link budget

Bit Rate 100,000 kbpsTX Bandwidth 500 MHzTX Power -16.1 dBmCenter frequency 4,752,000,000 HzPath Loss at 1m 45.98 dBReference distance 100 m Path Loss Distance 40 dBRX Antenna Gain 0 dBiRX Power -102.08 dBmNoise Figure 7 dBNo -167 dBm/HzRequire EbNo 11.5 dBImplementation Loss 0.5 dBLink Margin 3.42 dBZero Margin Range meters 148.26 m

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Submission

System simulation parameters

• Frequency band: 4.752GHz, 5.252 GHz (MB-OFDM band 4) • 10 dB bandwidth: 500 MHz • Transmit power: -16.1 dBm • Transmit filter: 3rd order Butterworth, corner frequency 180 kHz • Receive filter: 3rd order Butterworth, corner frequency 160 kHz • A/D converter: 528 MHz, 3 bits • Noise figure: 7 dB • Data rate: 100 kbps • PSDU size: 32 bytes • PRF (chip rate): 3.2 MHz • Length of DS spreading code: 16 • Length of preamble: 48 bits • Length of SFD: 32 bits • Length of PHR: 48 bits • Modulation: DBPSK • Demodulation method: differential detection • No frequency offset

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Submission

PER vs. distance

120 130 140 150 160 170 180 190 200 210 22010

-4

10-3

10-2

10-1

100

AWGN Channel

Distance [m]

PE

R

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Submission

PER vs. Eb/No

8 9 10 11 12 13 1410

-4

10-3

10-2

10-1

100

AWGN Channel

Eb/N

0 [dB]

PE

R

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doc.: IEEE 802.15-04/704r0

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PER vs. received power

-109 -108 -107 -106 -105 -104 -10310

-4

10-3

10-2

10-1

100

AWGN Channel

Received Power [dBm]

PE

R

January 2005


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Submission

Conclusions

• UWB band limited system• Meet all system requirements• Low signal repetition frequency to reduce ISI and need for high speed digital

circuits (lower power consumption)• “Narrow” UWB bandwidth to reduce complexity

• Remaining material will be presented at the next opportunity

January 2005


doc.: IEEE 802.15-04/704r0

Submission

Staccato Communications is actively collaborating with others

Objectives:

• “Best” Technical Solution • ONE Solution • Excellent Business Terms• Fast Time To Market

We encourage participation by any party who can help us reach our goals.

802.15.4a Early Merge Work

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

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