1. Pilot Sequence for VHT-DATA
July 2010
doc.: IEEE /0811r0
July 2010
Pilot Sequence for VHT-DATA
Date:
Authors:
Allert van Zelst, Qualcomm
Allert van Zelst, Qualcomm

2. July 2010
doc.: IEEE /0811r0
July 2010
Abstract
A pilot sequence is proposed for VHT-DATA that can be used in combination with the phase tracking during VHT-LTF ([1]).
Allert van Zelst, Qualcomm
Allert van Zelst, Qualcomm

3. July 2010
Introduction
As indicated in [1], single stream pilot tones during the VHT-LTFs can be used to improve MIMO channel estimation considerably, especially in case of phase noise and/or residual carrier frequency offset on the VHT-LTFs.
The most straightforward channel estimate on these pilot tones is a SIMO channel estimate.
To not require interpolation to get a MIMO channel estimate on the pilot tones, a single stream pilot mapping is proposed.
Allert van Zelst, Qualcomm

4. Pilot Sequence 0 1 2 3 4 5 6 7 1 -1 July 2010
For 20 and 40 MHz, the pilot sequence shall be the one spatial stream pilot sequence of 11n copied to the NSTS streams before the per-stream CSDs are applied.
For 80 MHz, the pilot sequence shall be the following sequence (which is the 40 MHz pilot sequence for NSTS = 1 extended with a [1, 1] on the right, resulting in the lowest PAPR on the pilot tones after applying [ ] rotation on the 20 MHz subbands), copied to the NSTS streams before the per-stream CSDs are applied: 0 1 2 3 4 5 6 7 1 -1
20 MHz 1ss pilot sequence
40 MHz 1ss pilot sequence
Allert van Zelst, Qualcomm

5. Application of Pilot Sequence in 20 MHz
July 2010
Application of Pilot Sequence in 20 MHz
The pilot tone mapping in 20 MHz shall be:
where is given by the NSTS = 1 row of Table of the 11n standard, and where n is the VHT-DATA symbol index starting at 0.
Including the pseudo random scrambling sequence, the pilot value for the kth tone, with k = {-21, -7, 7, 21}, is pn+zPnk, where z = 4 for VHT, and where pn is defined in Section of IEEE
Allert van Zelst, Qualcomm

6. Application of Pilot Sequence in 40 MHz
July 2010
Application of Pilot Sequence in 40 MHz
The pilot tone mapping in 40 MHz shall be:
where is given by the NSTS = 1 row of Table of the 11n standard , and where n is the VHT-DATA symbol index starting at 0.
Including the pseudo random scrambling sequence, the pilot value for the kth tone, with k = {-53, -25, -11, 11, 25, 53}, is pn+zPnk, where z = 4 for VHT, and where pn is defined in Section of IEEE
This doesn’t include the rotation per 20 MHz subband yet.
Allert van Zelst, Qualcomm

7. Application of Pilot Sequence in 80 MHz
July 2010
Application of Pilot Sequence in 80 MHz
The pilot tone mapping in 80 MHz shall be:
where is given in the table on slide 3, and where n is the VHT-DATA symbol index starting at 0.
Including the pseudo random scrambling sequence, the pilot value for the kth tone, with k = {-103, -75, -39, -11, 11, 39, 75, 103}, is pn+zPnk, where z = 4 for VHT, and where pn is defined in Section of IEEE
This doesn’t include the rotation per 20 MHz subband yet.
Allert van Zelst, Qualcomm

8. Application of Pilot Sequence in 160 MHz
July 2010
Application of Pilot Sequence in 160 MHz
For 160 MHz transmissions, the pilot mapping shall be the replication of the 80 MHz pilot mapping (as given on slide 7) in the two 80 MHz subbands for 160 MHz VHT-DATA symbols.
Allert van Zelst, Qualcomm

9. July 2010
Summary
A single-stream pilot mapping is proposed for VHT-DATA that can be used in combination with single-stream pilot mapping during VHT-LTFs ([1]).
This single-stream pilot mapping does not require interpolation on the pilot tones to get a MIMO channel estimate, which would be required to support a multi-stream pilot mapping.
Note that the proposed pilot mapping does allow interpolation on the pilot tones to get a MIMO channel estimate and do phase tracking per space-time stream.
Allert van Zelst, Qualcomm

10. July 2010
Straw Poll
Do you support adding the following paragraph in the specification framework document, 11-09/0992?
Pilot Subcarriers
[Copy the text of slides 4 – 8]
Allert van Zelst, Qualcomm

11. July 2010
References
[1] Kai Shi et al, “Phase Tracking During VHT-LTF”, IEEE /0771r0, July 2010
Allert van Zelst, Qualcomm