1. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 1 An Evaluation of DTV Pilot Power Detection IEEE P802.22 Wireless RANs Date: 2006-09-18 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 2 Introduction During the Study Group phase of this project the proposed method for detection of a DTV signal was to detect the power in a narrow band around the pilot location [1]. This presentation evaluates this technique using the DTV signal files provided by MSTV [2].

3. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 3 Observations About Pilot Power Detection The Pilot is a very narrowband feature which occurs is one of several well defined frequencies, which make it a strong feature for detection Since the pilot is in a narrow bandwidth it is susceptible to multipath (Rayleigh) fading, which makes detection more difficult Since there are multiple pilot locations that makes detection more difficult Since this feature is unique to ATSC DTV it can potentially also be used for signal classification

4. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 4 Pilot Locations This table is from the Draft [3]

5. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 5

6. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 6 Observations on Pilot Locations In [1] it was suggested that a 10 KHz filter be used However, the range of possible pilot locations span over 59 KHz In addition the accuracy of the local oscillator (LO) must be considered when setting the filter bandwidth Based on all these observations a filter of more than 60 KHz (probably more like 70 KHz) would need to be used. None the less, we performed our simulations using only a 10 KHz filter, as proposed in [1] If a 70 KHz filter were used the results would be approximately 8.5 dB worse

7. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 7 Detector Summary Down convert IF signal to bring the pilot close to DC Filter with 10 KHz lowpass filter Reduce sampling rate to 10 KHz The test statistic is the estimate of the power in this 10 KHz band Set the detector threshold so that we have a 10% false alarm rate Include the effects of noise uncertainty 30 samples = 3 ms 60 samples = 6 ms

8. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 8 Expectations for this Detector The power in the pilot is 11.3 dB less than the power in the data portion of the signal. –The signal power is 11.3 dB lower The noise in 10 KHz is 28 dB less than in 6 MHz –The noise power is 28 dB lower The combined effect of these two factors is an increase of approximately 17 dB. That is huge! We get flat Rayleigh fading in the 10 KHz band –This is going to have a strong negative effect on the detector –Since this is fixed wireless we cannot just wait around for the channel to get better – Not too much benefit from time diversity

9. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 9 Strong Pilot

10. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 10 Strong Pilot

11. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 11 Strong Pilot

12. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 12 Average Pilot

13. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 13 Average Pilot

14. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 14 Average Pilot

15. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 15 Weak Pilot

16. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 16 Weak Pilot

17. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 17 Weak Pilot

18. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 18 Very Weak Pilot

19. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 19 Very Weak Pilot

20. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 20 Very Weak Pilot

21. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 21 Pilot Outside Filter Bandwidth

22. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 22 Pilot Outside Filter Bandwidth

23. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 23 Pilot Outside Filter Bandwidth

24. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 24 Average over 48 Signal Files 48 out of 50 of the files had their pilot within the filter bandwidth So we averaged the P MD curves over all these 48 files By averaging over all these files we effectively average over the effects of Rayleigh fading

25. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 25 Average over 48 Signal Files

26. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 26 Average over 48 Signal Files

27. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 27 Conclusions Even if we do not consider the effects of noise uncertainty the simulation results show that the effects of Rayleigh fading prevent this detector from meeting the -116 dB detection requirement In addition the possible pilot locations span about 60 KHz If we consider after the cut over date to DTV the span of the pilot locations is reduced to around 20 KHz

28. doc.: IEEE 802.22-06/XXXXr0 Submission September 2006 Steve Shellhammer, QualcommSlide 28 1.John Notor, Proposal for Part 15.244 Cognitive Radio Operation in the TV Band, IEEE 802.18-04/30r2, July 2004 2.Advanced Television Standards Committee, ATSC Recommended Practice: Receiver Performance Guidelines, A/74, June 2004 3.IEEE P802.22/D0.1, 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, Version 0.1, May 2006 References