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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 [roberto@staccatocommunications.com]
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 802.15-04/704r1
January 2005
Roberto Aiello, Staccato CommunicationsSlide 2
doc.: IEEE 802.15-04/704r1
Submission
Staccato CommunicationsUWB PHY Proposal for TG4a
Roberto Aiello, Ph.D.
Torbjorn Larsson, Ph.D.
Staccato Communicationsr@staccatocommunications.com
January 2005
Roberto Aiello, Staccato CommunicationsSlide 3
doc.: IEEE 802.15-04/704r1
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 802.15-04/704r1
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 802.15-04/704r1
Submission
Features
• Meets all system requirements
• Low signal repetition frequency to reduce ICI/ISI and need for high speed digital circuits (lower power consumption)
• “Narrow” UWB bandwidth to reduce complexity
• Use of differential encoding on chip level to reduce receiver complexity and provide maximum robustness
January 2005
Roberto Aiello, Staccato CommunicationsSlide 6
doc.: IEEE 802.15-04/704r1
Submission
Summary
• Band limited UWB system compliant with FCC 02-48, UWB Report & Order
• 500MHz bandwidth at -10dB
• Two bands centered at 4.752 GHz and 5.252 GHz (MB-OFDM band 4 and 5)
• Symbol rates varying from 12.5 kbps to 1.6 Mbps at PHY-SAP
• Due to time constraints, this presentation addresses– Modulation scheme, channelization and packet structure– Performance in AWGN
• Remaining material will be presented at the next opportunity in March 2005– Performance in multipath– Implementation feasibility– Self evaluation criteria– Other issues that will emerge from group’s feedback
January 2005
Roberto Aiello, Staccato CommunicationsSlide 7
doc.: IEEE 802.15-04/704r1
Submission
Multipath
0 100 200 300 400 500 6000
0.05
0.1
Time [ns]
Multipath Channel Output
CM8 (Industrial NLOS)
PRF = 3.2 MHz
January 2005
Roberto Aiello, Staccato CommunicationsSlide 8
doc.: IEEE 802.15-04/704r1
Submission
System Description
DifferentialDetection
Codeword C or - C differentially encoded
DifferentialDetection
Add Coherently
Non-Coherent detection of differentially encoded
codewords (1,C) and (1,- C)
De-Spreading
PRF = 3.2 MHz
January 2005
Roberto Aiello, Staccato CommunicationsSlide 9
doc.: IEEE 802.15-04/704r1
Submission
System Description, Continued
• Impulse radio combined with direct-sequence spreading
• Differential BPSK modulation of chips
• A code word covers one BPSK-modulated symbol
• Different piconets use different code words
• Differential encoding of chips allows the use of differential chip detection in the receiver– Differential detection is carried out separately for each multipath
component– Differential combining of multipath components– No need for channel estimation– Simple receiver structure with decent performance
January 2005
Roberto Aiello, Staccato CommunicationsSlide 10
doc.: IEEE 802.15-04/704r1
Submission
System Description, Continued• For improved performance, non-coherent symbol detection (with
coherent energy integration across one code word) can be used– Symbol detection is carried out separately for each multipath
component
– Non-coherent combining of multipath components
– Still no need for channel estimation
• PRF (chip rate): 3.2 MHz– Low enough to avoid interchip interference (ICI) with all 802.15.4a
multipath models
– High enough to eliminate the need for frequency offset correction (with some performance loss) when differential detection is used
• Pulse shape: 3rd-order Butterworth or similar
• FEC: 16-state rate-1/2 convolutional code and symbol repetition
January 2005
Roberto Aiello, Staccato CommunicationsSlide 11
doc.: IEEE 802.15-04/704r1
Submission
Differential Multipath Combining
nx ,1nx ,2
nx ,3
1,1 nx 1,2 nx
1,3 nx
*,31,3
*,21,2
*,11,1 ReReRe nnnnnn xxxxxx
January 2005
Roberto Aiello, Staccato CommunicationsSlide 12
doc.: IEEE 802.15-04/704r1
Submission
System Parameters
Data Rate [kbps] Length of spreading code in PHR and PSDU
Duty Cycle [%] Length of SFD in bits
12.5 16 12.5 32 25 16 25 32 50 16 50 32 100 16 100 32 200 8 100 16 400 4 100 8 800 2 100 5 1600 1 100 3
• Length of spreading code in preamble is always 16
• Duty cycle < 100% means that code words of length 16 are transmitted with a space in between
– An extra initial chip is added to serve as phase reference for the first chip in the code word
– For instance, to achieve a duty cycle of approximately 50%, 17 chips are transmitted followed by a space equivalent to 15 chip periods
PHR = PHY Header; PSDU = PHY Service Data Unit; SFD = Start-of-Frame Delimiter
January 2005
Roberto Aiello, Staccato CommunicationsSlide 13
doc.: IEEE 802.15-04/704r1
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
100 kbps
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 14
doc.: IEEE 802.15-04/704r1
Submission
Spreading Codes (Length 16)
-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
These code words (c) were found by exhaustive search based on the three following properties:
–Low cyclic autocorrelation–Low cyclic cross-correlation between code words c–Low cross-correlation between code words (1,c)
and (1,-c)
January 2005
Roberto Aiello, Staccato CommunicationsSlide 15
doc.: IEEE 802.15-04/704r1
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 16
doc.: IEEE 802.15-04/704r1
Submission
Receiver Architectures
LPFX
LOLNA/VGA
Timing
X LPF ADC
ADC
DiffDetection
MultipathCombing
DSDe-Spread
SymbolCombining
ViterbiDecoding
AcquisitionGain
Differential chip detection during acquisition and non-coherent symbol detection during data demodulation
Differential chip detection during both acquisition and data demodulation
A.
B.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
January 2005
Roberto Aiello, Staccato CommunicationsSlide 17
doc.: IEEE 802.15-04/704r1
Submission
More on Receiver Architectures
• In both architectues, acquisition is based on differential detection/combining– Does not require frequency offset correction and therefore leads to shorter
preamble (=> less overhead)– Small performance loss at 20 ppm frequency error– If desired, frequency offset estimation can be carried out in parallel with
synchronization
Architecture A • Differential chip detection for data demodulation
– Frequency offset correction may still be applied during PHR and PSDU to improve performance
Architecture B.• Non-coherent symbol demodulation for data demodulation
– Significant performance improvement, since we are now summing energy coherently across a whole codeword (which for data rates <= 100 kbps is 16 chips long)
– Requires frequency offset estimation (during acquisition) and correction (during data demodulation)
January 2005
Roberto Aiello, Staccato CommunicationsSlide 18
doc.: IEEE 802.15-04/704r1
Submission
Link Budget
Bit Rate 100,000 bpsTX 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/HzRequired Eb/No 11.5 dBImplementation Loss 0.5 dBLink Margin 3.42 dBZero Margin Range meters 148.26 m
January 2005
Roberto Aiello, Staccato CommunicationsSlide 19
doc.: IEEE 802.15-04/704r1
Submission
System Simulation Parameters
• Frequency band: 4.752GHz (MB-OFDM band 4) • 10 dB bandwidth: 500 MHz • Transmit power: -16.1 dBm • Transmit/Receive filter: 3rd order Butterworth, corner frequency 180 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 20
doc.: IEEE 802.15-04/704r1
Submission
Spectrum
4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6-80
-75
-70
-65
-60
-55
-50
-45
-40
GHz
dB
m
Power over 1 MHz Bandwidth
ProposalFCC Mask
TX Power: -16.1 dBm
January 2005
Roberto Aiello, Staccato CommunicationsSlide 21
doc.: IEEE 802.15-04/704r1
Submission
PER vs. Distance in AWGN (100 kbps)
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 22
doc.: IEEE 802.15-04/704r1
Submission
PER vs. Eb/No (100 kbps)
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 23
doc.: IEEE 802.15-04/704r1
Submission
PER vs. Received Power (100 kbps)
-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 24
doc.: IEEE 802.15-04/704r1
Submission
Conclusions
• UWB band limited system
• Meet all system requirements
• Low signal repetition frequency to reduce ICI 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 25
doc.: IEEE 802.15-04/704r1
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
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