Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS)
description
Transcript of 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
Roberto Aiello, Staccato CommunicationsSlide 3
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 4
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 5
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 6
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 7
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]
January 2005
Roberto Aiello, Staccato CommunicationsSlide 8
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 9
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
PSDU(LENGTH*8+4)*2 symbols
1 symbol = 8 chips
Preamble768 chips
SFD512 chips
PHR48 symbols
PSDU(LENGTH*8+4)*2 symbols
1 symbol = 16 chips
800 kbps
Preamble96 chips
SFD80 chips
PHR48 symbols
PSDU(LENGTH*8+4)*2 symbols
1 symbol = 2 chips
1600 kbps
Preamble48 chips
SFD48 chips
PHR48 symbols
PSDU(LENGTH*8+4)*2 symbols
1 symbol = 1 chip
January 2005
Roberto Aiello, Staccato CommunicationsSlide 10
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 11
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 12
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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.
January 2005
Roberto Aiello, Staccato CommunicationsSlide 13
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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).
January 2005
Roberto Aiello, Staccato CommunicationsSlide 14
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 15
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 16
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 17
doc.: IEEE 802.15-04/704r0
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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 18
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 19
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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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 20
doc.: IEEE 802.15-04/704r0
Submission
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
Roberto Aiello, Staccato CommunicationsSlide 21
doc.: IEEE 802.15-04/704r0
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
Roberto Aiello, Staccato CommunicationsSlide 22
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