Pilot Sequence for VHT-DATA July 2010 doc.: IEEE 802.11-10/0811r0 July 2010 Pilot Sequence for VHT-DATA Date: 2010-07-12 Authors: Allert van Zelst, Qualcomm Allert van Zelst, Qualcomm

July 2010 doc.: IEEE 802.11-10/0811r0 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

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

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 [1 -1 -1 -1] 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

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 20-18 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 17.3.5.9 of IEEE802.11. Allert van Zelst, Qualcomm

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 20-19 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 17.3.5.9 of IEEE802.11. This doesn’t include the rotation per 20 MHz subband yet. Allert van Zelst, Qualcomm

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 17.3.5.9 of IEEE802.11. This doesn’t include the rotation per 20 MHz subband yet. Allert van Zelst, Qualcomm

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

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

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

July 2010 References [1] Kai Shi et al, “Phase Tracking During VHT-LTF”, IEEE 802.11-10/0771r0, July 2010 Allert van Zelst, Qualcomm