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Sudhir Srinivasa et al.Slide 1
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Slide 1
80MHz Tone Allocation
Authors: Date: 2010-05-17
Name Affiliations Address Phone email
Sudhir Srinivasa Marvell 5488 Marvell Lane, Santa Clara CA, 95054
Hongyuan Zhang Marvell 5488 Marvell Lane, Santa Clara CA, 95054
+1-408-222-1837
Raja Banerjea Marvell 5488 Marvell Lane, Santa Clara CA, 95054
+1-408-222-3713
Eldad Perahia Intel 2111 NE 25th Ave, Hillsboro OR 97124, USA
Richard van Nee Qualcomm Netherlands [email protected]
VK Jones Qualcomm Santa Clara [email protected]
Ning Zhang Atheros 5480 Great America Pkwy Santa Clara, CA 95054
+1-408-773-5363
Vinko Erceg Broadcom San Diego, CA [email protected]
Uikun Kwon Samsung [email protected]
Sudhir Srinivasa et al.Slide 2
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Introduction
• Functional requirements as per the spec framework document [1]:• R3.1.A (Channelization): The draft specification shall include
support for 80 MHz PHY transmission.
• Possible preambles for 80MHz OFDM have been discussed in [2, 3].
• This presentation will focus on a possible data and pilot tone mapping for 80MHz VHT data.
Sudhir Srinivasa et al.Slide 3
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Tone Allocation
• Legacy preamble portion (LLTF/LSIG) needs to be repeated across each of the 20MHz sub-bands– (6+5) guard tones in each 20MHz legacy portion, therefore (6+5) guard
tones in 80MHz.
– Spectrum mask and filter design will have to conform to (6+5) guard tones anyway
• Propose to use (6 + 5) guard tones, 3 DC tones in 80MHz
-128127122
2-2-122
121 Data/Pilot Tones 121 Data/Pilot Tones6 Guard Tones 5 Guard Tones3 DC Tones
Freq
Subcarrier Index
Sudhir Srinivasa et al.Slide 4
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Location of pilot subcarriers
• The 802.11n spec mandates that – LSIG of 20MHz packets have pilots at {±7, ±21} and
• Repetition of the LSIG sequence across 80MHz – LSIG in an 80MHz 11ac packet will have pilots at location pairs
belonging to {±11, ±25, ±39, ±53, ±75, ±89, ±103, ±117}.
• Not desirable to change pilot positions between the legacy (11a/n) and VHT parts of the packet.– Some implementers may average pilots across and legacy
preamble (SIG fields) and VHT data.
• For simple receiver design, better to pick 80MHz pilots among these 16 tones.
Sudhir Srinivasa et al.Slide 5
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Number of pilot subcarriers
• Simulations show that the performance gap between using 8 and 10 pilots is small. (See backup slides)
• Reducing the number of pilots to 6, however, results in a ~1dB loss in performance in some scenarios (See backup slides)
• We propose that 11ac packets use 8 pilots during 80MHz VHT-DATA portion.– Can be chosen such that they are maximally separated, with
indices {±103, ±75, ±39, ±11}
Sudhir Srinivasa et al.Slide 6
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
References
1. IEEE802.11-09/0992r3, R. Stacey et al., Proposed Specification Framework for TGac
2. IEEE802.11-10/0070r1, H. Zhang et al., 802.11ac Preamble
3. IEEE802.11-10-0130r0, Y. Tu et. Al., Proposed TGac Preamble
Sudhir Srinivasa et al.Slide 7
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Simulation Results 1
Sudhir Srinivasa et al.Slide 8
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Simulation Results 2
Sudhir Srinivasa et al.Slide 9
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Strawpolls
Sudhir Srinivasa et al.Slide 10
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Strawpoll #1:
• Do you support to add to the specification frame work document (IEEE 802.11-09/0992r9) – 3.x Data Formats
• 3.x.2 OFDM Modulation: The draft specification shall have 3 DC tones at (0, ±1) in 80MHz VHT data field.
– Yes
– No
– Abstain
Sudhir Srinivasa et al.Slide 11
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Strawpoll #2:
• Do you support to add to the specification frame work document (IEEE 802.11-09/0992r9) – 3.x Data Formats
• 3.x.2 OFDM Modulation: The draft specification shall have 5 null tones at the upper tone edges (tone indices 123, 124, 125, 126, 127) and 6 null tones at the lower tone edges (tone indices -128, -127, -126, -125, -124, -123) of the 80MHz VHT data.
– Yes– No– Abstain
Sudhir Srinivasa et al.Slide 12
doc.:IEEE 802.11-10/0370r1
Submission
May 17, 2010
Strawpoll #3:
• Do you support to add to the specification frame work document (IEEE 802.11-09/0992r9)– 3.x Data Formats
• 3.x.1 Pilot Subcarriers: The draft specification shall have 8 pilot tones, with the positions {±103, ±75, ±39, ±11}, for 80MHz VHT data.
– Yes
– No
– Abstain
