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TRANSCRIPT
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 1
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Suggestions on the pilot pattern of OFDM PHY]
Date Submitted: [July 14 2010]
Source: [Wei An, Yosi Stein, Chuck Millet ] Company [Analog Devices, Inc.]
Address [3 Technology Way]
Voice:[781-461-3730], FAX: [], E-Mail:[[email protected]]
Re: [Pilot Schemes]
Abstract: This presentation describes a pilot proposal different from the current scheme. This addresses
comments 1420, 1422, 1423
Purpose: [For information]
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.
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Proposal of Equal-space Pilot Pattern for
802.15.4g OFDM PHY
July, 2010
Wei An, Yosi Stein , Analog Devices, IncSlide 2
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Design Considerations
• Two-dimensional pilot allocation:– Frequency dimension
• Handles delay spread
• Maximum 24us
– Time dimension• Handles Doppler effect
• Maximum 100~200 Hz
• Equal space in both dimensions– Frequency dimension: proved in [Negi&Cioffi]
– Time dimension: can be proved in a similar way
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 3
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Frequency Dimension
• Pilot tones are optimal when evenly distributed [Negi&Cioffi]
• Max number of carrier tones per pilot tone = OFDM symbol length / Delay spread [Negi&Cioffi]– Delay spread = 24us
– OFDM symbol length = 96us
– 4 carrier tones per pilot tone
• These are Minimum requirements
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 4
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Sampling Viewpoint• Pilot tones sample Channel Impulse Response (CIR)
in frequency domain
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 5
Length of an
OFDM symbol
24ustf
24ustf
24ustf
96us
Sampled by pilots in
frequency domainCIR after sampling
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Time Dimension
• Doppler effects result in channel variation in time
• Can be captured by same-index pilot tones of a sequence of OFDM symbols
• Equal time distance between same-index pilots
• Max time period between same-index pilot tones– Max Doppler frequency = 200Hz
– Max time period = 1/400 s = 2.5ms
– Approximately 20 OFDM symbols
• These are Minimum requirements
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 6
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Sampling Viewpoint• Same-index pilots samples channel variation in time
domain
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 7
400 Hzf t
t
20 symbols
400 Hzf
3 times carrier
spacing
Doppler SpectrumSampled by same-
index pilots in time
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Requirements on Pilot Allocation
• Frequency dimension : At most 4 tones per pilot
• Time dimension: At most 20 OFDM symbols between same-index pilots
• Equal space in both dimensions– Optimal performance
– Simplicity in receiver design
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 8
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Latest Proposal (15-10-0474-00-004g)
• Not equal-space in either dimension
• The irregularity of pilot location causes– Less optimal performance
– Difficulty in receiver design
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 9
• Pilot map of option1 (13 pilot sets grouped in thick-line box)
26 O
FD
M S
ym
bols
Carriers Indexed from -52 to 52
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Latest Proposal (Other Options)
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 10
• Option 2: 7 pilot sets
14 O
FD
M
Sym
bols
Carriers Indexed from -26 to 26
• Option 3: 7 pilot sets
• Option 5: 2 pilot sets• Option 4: 4 pilot sets
Carriers Indexed from -13 to 13
14 O
FD
M
Sym
bols
Index from -7 to 7
8 O
FD
M
Sym
bols
Index from -3 to 3
4 O
FD
M
Sym
bols
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Current Standard Draft
(d1P802-15-4g_Draft_Standard)
• Not equal-space in frequency dimension for option 1,2,3 and 4
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 11
6 O
FD
M
Sym
bols
Carriers Indexed from -52 to 52
6 O
FD
M
Sym
bols
Carriers Indexed from -26 to 26
Carriers Indexed from -13 to 13
6 O
FD
M
Sym
bols
Index from -7 to 7
4 O
FD
M
Sym
bols
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
New Proposal: Option 1
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 12
• 103 carriers with 7 pilots; 5 pilot sets
10 O
FD
M
Sym
bols
Carriers Indexed from –52 to 51
0 indexed carrier; Not used; Marked with grey color
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
New Proposal: Option 2
• 52 carriers with 4/3 pilots; 4 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 13
8 O
FD
M
Sym
bols
Carriers Indexed from –26 to 26
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
New Proposal: Option 3
• 26 carriers with 2 pilots; 3 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 14
6 O
FD
M
Sym
bols
Carriers Indexed from –13 to 13
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
New Proposal: Option 4
• 14 carriers with 2 pilots; 2 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 15
4 O
FD
M
Sym
bols
Carriers Indexed from –7 to 7
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Option 5
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 16
Index from -3 to 3
2 O
FD
M
Sym
bols
• 6 carriers with 2 pilots; 1 pilot sets
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Pilot Indices of New Proposal: Option 1
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 17
Pilot set 1 -52 -37 -22 -7 8 23 38
Pilot set 2 -49 -34 -19 -4 11 26 41
Pilot set 3 -46 -31 -16 -1 14 29 44
Pilot set 4 -43 -28 -13 2 17 32 47
Pilot set 5 -40 -25 -10 5 20 35 50
• 103 carriers with 7 pilots; 5 pilot sets
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Pilot Indices of New Proposal: Option 2
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 18
• 52 carriers with 3 or 4 pilots; 4 pilot sets
Pilot set 1 -26 -10 6 22
Pilot set 2 -22 -6 10 26
Pilot set 3 -18 -2 14
Pilot set 4 -14 2 18
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Pilot Indices of New Proposal: Option 3
• 26 carriers with 2 pilots; 3 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 19
Pilot set 1 -10 2
Pilot set 2 -6 6
Pilot set 3 -2 10
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Pilot Indices of New Proposal: Option 4
• 14 carriers with 2 pilots; 2 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 20
Pilot set 1 -6 2
Pilot set 2 -2 6
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doc.: IEEE 802.15 15-10-0577-00-004g
Submission
Pilot Indices of New Proposal: Option 5
• 6 carriers with 2 pilots; 1 pilot sets
July, 2010
An, Stein, Millet, Analog Devices, Inc.Slide 21
Pilot set 1 -2 2