1. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 1 Spectral Mask Implications IEEE P802.22 Wireless RANs Date: 2008-04-10 Authors: Notice: This document has been prepared to assist IEEE 802.22. 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 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf 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 Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee.org.patcom@iee.org >

2. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 2 Abstract An evaluation of the impact of the 802.22 Spectral Mask on the 1-dB compression point of the power amplifier

3. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 3 Spectral Mask The 802.22 draft [1] requires that the field strength outside the occupied channel is 4.8  V/m, measured at 3 meters in a 120 kHz bandwidth According to Gerald [2] this equates to a spectral mask of -100 dBr outside the occupied channel The draft [1] does not have an actual spectral mask so a spectral mask needs to be added to the draft. In this document we will use the spectral mask from [2]

4. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 4 Non-Linear PA Model The nonlinearity of the power amplifier (PA) distorts the OFDM spectrum In this document the 802.11 nonlinear PA model is used This model was used in the evaluation of 802.11n proposals [3] and was originally used in modeling 802.11b [4]. This same form of non-linearity is specified in the 802.22 channel models document [5]

5. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 5 Non-Linear PA Model A sat

6. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 6 1-dB Compression Point The 1-dB compression point is the PA input value at which the PA output is 1 dB less than it would be in a perfectly linear amplifier To ensure linear operation one must operate well below the 1-dB compression point The closer the signal is to the 1-dB compression point the more distortion is produced

7. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 7 Simulation Procedure A simulation was run to determine the value of the 1-dB compression point for a 1 watt CPE Over-sample the signal by a factor of four Process signal through nonlinear PA model Plot power spectral density of PA output Increase 1 dB compression point and repeated until the PA output meets the spectral mask Report final 1-dB compression point

8. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 8 Power Spectral Density of PA Output with 40 dB Back-off

9. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 9 1-dB Compression Point To meet spectral mask the 1-dB compression point must be 40 dB above the average power level –This is referred to as a 40 dB back-off This means for a 1 watt (30 dBm) CPE the PA must have a 10 kW (70 dBm) 1-dB compression point –This is a very high-power PA for the CPE For a 100 watt BS the PA must have a 1 MW 1-dB compression point –This is a very high-power PA for the BS

10. doc.: IEEE 802.22-08/0111r0 Submission April 2008 Steve Shellhammer, QualcommSlide 10 References 1.IEEE P802.22™/ DRAFTv1.0 Draft Standard for Wireless Regional Area Networks Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV Bands, April 2008 2.Gerald Chouinard, Wireless Microphone Sensing, IEEE 802.22-07/530r0, November 2007 3.Adrian P Stephens, IEEE 802.11 TGn Comparison Criteria, IEEE 802.11-03/814r19, March 2004 4.Mark Webster, Suggested PA Model for 802.11 HRb, IEEE 802.11-00/294r0, September 2000 5.Eli Sofer and Gerald Chouinard, WRAN Channel Modeling, IEEE 802.22-05/55r7, August 2005