1. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 1 PAPR in LTF’s in with and without rotation of the upper subcarrier Notice: This document has been prepared to assist IEEE 802.11. 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2006-06-06 Authors: NameCompanyAddressPhoneemail Assaf KasherIntelassaf.kasher@i ntel.com

2. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 2 Abstract This presentation addresses letter ballot comments with the CID’s in the table on the right: These comments propose to remove the 90° rotation from the upper 20Mhz of a 40MHz channel. These comments should be countered based on the analysis given in this presentation

3. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 3 1371820.1.3 rotation by j does not change the PAPR as seen by the analog electronics delete the sentence "To reduce the pak-to-average …." 221920.3.3.2.1. 2 90 degree rotation does not help the PAPR as seen by the analog section delete line 9-10 2221220.3.3.2.1. 2 90 degree rotation is not requiredremove gamma in equation 20-7 223120.3.3.2.1. 2 delete the definition of Gamma 2251020.3.3.2.1. 3 90 degree rotation is unnecessarydelete line 10 2271820.3.3.2.1. 3 90 degree rotation is unnecessarydelete line 18 2261520.3.3.2.1. 3 90 degree rotation is unnecessaryremove Gamma 229120.3.3.2.1. 4 90 degree rotation is unnecessaryremove j multiplication in row 3 cloumn 2 of table n66 231120.3.3.2.2. 2 90 degree rotationin the upper 20MHz band is unnecessary change equation in row 3 column 2 accordingly 2341720.3.3.2.2. 3 90 degree rotation is unnecessarydelete Gamma and the definition of Gamma 235920.3.3.2.2. 3 90 degree rotation is unnecessarydelete Gamma and the definition of Gamma 2371520.3.3.3 90 degree rotation is unnecessarydelete Gamma and the definition of Gamma 2381420.3.3.3.3. 2 90 degree rotation is unnecessarymodify the equation for the tones in the upper band accordingly. 239620.3.3.3.4 90 degree rotation is unnecessarydelete Gamma

4. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 4 Introduction The 90° rotation of the upper channel has been introduced to reduced PAPR (Peak to Average Power Ratio) in the transmission of the STF and LTF’s. PAPR is defined as:

5. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 5 PAPR results: L-STF Peak to Average Power Ratio [dB] realimaginaryabsolute No Rotation 40Msps8.076010478.07601055.0996852 With Rotation 40Msps2.79294764.31885252.0893852 No Rotation 80Msps8.076010478.07601055.0996852 With Rotation 80Msps6.1247726.91106355.249665

6. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 6 PAPR results: L-LTF Peak to Average Power Ratio [dB] realimaginaryabsolute No Rotation 40Msps6.118239596.09187673.1658108 With Rotation 40Msps6.592197255.89470394.1857537 No Rotation 80Msps6.118239596.09187673.1658108 With Rotation 80Msps6.878942576.12593364.1857537

7. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 7 PAPR results – HT-LTF Peak to Average Power Ratio [dB] realimaginaryabsolute No Rotation 40Msps8.547.275.63 With Rotation 40Msps6.326.343.41 No Rotation 80Msps (FFT 256)8.547.275.63 With Rotation 80Msps (FFT 256)9.377.496.36

8. doc.: IEEE 802.11-06/1595r1 Submission June 2006 Assaf Kasher (Intel)Slide 8 Conclusion We can see that the 90° rotation improves PAPR significantly in the L-STF and in the HT-LTF when the sampling rate is 40Msps. There is not significant degradation in PAPR in the other cases. We therefore propose to keep the 90° rotation. We propose removing the sentence “To reduce the peak to average power ratio,” from page 186, line 71. We propose removing the sentence “The 90 rotation helps keep the PAPR of the L-STF in 40 MHz comparable to that in 20 MHz.” from line 14 of page 214.looooon