doc.: IEEE 802.11-10/0786r0 Submission July 2010 Daewon Lee, LG Electron Slide 1 Pilot Sequence design up to 8 Spatial Streams Date: 2010-07-13 Authors: N am e A ffiliations A ddress Phone em ail D aew on Lee LG Electronics, Inc. LG R& D C om plex 533, H ogye-1dong,D ongan-G u, A nyang-Shi, K yungki-D o, 431-749, K orea +82-31-450-7897 daewon.lee@ lge.com Bonghoe K im LG Electronics, Inc. LG R& D C om plex 533, H ogye-1dong,D ongan-G u, A nyang-Shi, K yungki-D o, 431-749, K orea +82-31-450-4131 bonghoe.kim@ lge.com Byeongw oo K ang LG Electronics, Inc. LG R& D C om plex 533, H ogye-1dong,D ongan-G u, A nyang-Shi, K yungki-D o, 431-749, Korea +82-31-450-4131 byeongw oo.kang@ lge.co m
Transcript
doc.: IEEE 802.11-10/0786r0
Submission
July 2010
Daewon Lee, LG ElectronicsSlide 1
Pilot Sequence design up to 8 Spatial StreamsDate: 2010-07-13
Authors:
Name Affiliations Address Phone email
Daewon Lee LG Electronics, Inc.
LG R&D Complex 533, Hogye-1dong, Dongan-Gu, Anyang-Shi, Kyungki-Do, 431-749, Korea
We discuss some of the pilot design principles for 11ac and propose use a single pilot mother matrix in which all pilots for each bandwidth and spatial stream get its pilot sequence values
doc.: IEEE 802.11-10/0786r0
Submission
Pilot Sequence Design
• Design Target– Pilot sequences must be defined up to 8 spatial streams
– Pilot sequence also must be defined for 80 MHz
• Design principles– Performance difference between different pilot sequences is not
expected to be large
– Rather than defining a pilot sequence for each instance (number of spatial streams & bandwidth size) define a large sequence matrix for all spatial streams and bandwidth may be preferable
July 2010
Daewon Lee, LG ElectronicsSlide 3
doc.: IEEE 802.11-10/0786r0
Submission
Discussion (1/2)
• performance in various scenarios– It will be important to consider tracking performance in various
scenarios
– orthogonal pilot sequence across spatial streams may give robust performance in case of correlated Tx antenna configurations
– some studies [1] show that having orthogonal pilot design may be more robust for highly correlated channels
• pilot tracking functionality– Orthogonal pilots do not necessary mean pilot tracking
functionality is mandated to gather pilots over multiple OFDM symbols for processing
July 2010
Daewon Lee, LG ElectronicsSlide 4
doc.: IEEE 802.11-10/0786r0
Submission
Discussion (2/2)
• Complexity for supporting orthogonal pilot design– 11n pilots has been design to be orthogonal between spatial streams (note
that not all pilot tones in 40MHz are time domain orthogonal)– if orthogonal pilot tone tracking is implemented for 11n then same
functionality can be re-utilized in 11ac– no mandate of separate phase tracking per spatial stream
• may not be needed if single LO is used at Tx/Rx
– no additional complexity for phase tracking is expected
• PAPR of pilot sequence– PAPR increase due to certain ‘bad’ pilot sequences design is expected to be
marginal because OFDM data tones will effect the PAPR the most– some PAPR analysis for pilot in VHT data portion is shown in the Annex
• We give one candidate proposal for the pilot sequences for data portion of the VHT PLCP preamble
• We propose to further consider different pilot sequence for each spatial streams
• We propose to further consider orthogonal pilot sequence design to make pilot tracking more robust against various deployment scenarios
July 2010
Daewon Lee, LG ElectronicsSlide 10
doc.: IEEE 802.11-10/0786r0
Submission
Reference
• [1] Aoki, T.; Sandell, M.; , "Analysis of pilots for residual frequency offset estimation in MIMO OFDM systems," Wireless Communications, IEEE Transactions on , vol.8, no.3, pp.1128-1132, March 2009.
July 2010
Daewon Lee, LG ElectronicsSlide 11
doc.: IEEE 802.11-10/0786r0
Submission
Annex
July 2010
Daewon Lee, LG ElectronicsSlide 12
doc.: IEEE 802.11-10/0786r0
Submission
Annex. PAPR analysis of proposed pilot sequence (1/3)
• Data PAPR analysis as reference
• 20 MHz BW with proposed pilot sequence
• Different CDF curves represent CDF of each spatial stream
July 2010
Daewon Lee, LG ElectronicsSlide 13
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1Data PAPR [dB] CDF
PAPR [dB]
CD
F
20MHz
40MHz80MHz
0 2 4 6 8 10 12 140
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1PAPR [dB] CDF of 20 MHz BW
PAPR [dB]
CD
F
doc.: IEEE 802.11-10/0786r0
Submission
Annex. PAPR analysis of proposed pilot sequence (2/3)
• 40 MHz BW with proposed pilot sequence & PAPR reduction γ sequence [ +1 +j ] used
• Different CDF curves represent CDF of each spatial stream
July 2010
Daewon Lee, LG ElectronicsSlide 14
0 2 4 6 8 10 12 140
0.1
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1Data PAPR [dB] CDF
PAPR [dB]
CD
F
20MHz
40MHz80MHz
0 2 4 6 8 10 12 140
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1PAPR [dB] CDF of 40 MHz BW
PAPR [dB]
CD
F
doc.: IEEE 802.11-10/0786r0
Submission
Annex. PAPR analysis of proposed pilot sequence (3/3)
• 80 MHz BW with proposed pilot sequence & PAPR reduction γ sequence [ +1 +j +1 +j ] used
• Different CDF curves represent CDF of each spatial stream
