1. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 1 Use of collaborative sensing to reduce false positive results IEEE P802.22 Wireless RANs Date: 2008-05-01 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 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 2 Edge of coverage of a 1 MW, 300 m height DTV station Required DTV field strength: 41 dBuV/m at 615 MHz Propagation model = ITU-R P.1546 –F(50,90) = 41 dB(μV/m)(50% location, 90% time) –Distance of protected contour from the DTV transmitter = 118 km –σ location = 5.5 dB F(50,50) = 46.7 dB(μV/m) –σ time = (F(50,50)-F(50,90))/Q -1 (90%)= (56-41)/1.28= 4.46 dB Composite propagation –Sum of two log-normal distributions = log-normal (μ 1 +μ 2, σ 1 2 +σ 2 2 ) DTV signal variability at protected contour = log-normal (μ= 46.7 dB(μV/m), σ= 7.08 dB)

3. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 3 Conversion from field strength to SNR at the input of the sensing detector

4. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 4 SNR probability density function for a sensing CPE located at the edge of a DTV protected contour μ= 8.8 dB σ= 7.08 dB DTV signal level at edge of contour F(50,50) F(50,90) Required sensing threshold F(50,10)

5. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 5 Sensing technique performance (Thomson DTV segment detector) Sampling= 4.06 ms Pfa= 10 %

6. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 6 Sensing technique performance (Thomson DTV segment detector) Sampling= 4.06 ms Pfa= 10 % DTV signal level at edge of contour μ= 8.8 dB σ= 7.08 dB

7. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 7 Sensing technique performance (Thomson DTV segment detector) Sampling= 4.06 ms Pfa= 10 % DTV signal level at edge of contour

8. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 8 Sensing technique performance (Thomson DTV segment detector) Sampling= 4.06 ms Pfa= 10 % P detection = 99.482% DTV signal level at edge of contour

9. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 9 Sensing technique performance (I2R covariance absolute value detector) Sampling= 4 ms Pfa= 1 % P detection = 99.843% DTV signal level at edge of contour

10. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 10 Sensing techniques performance comparison Pd=98.535% Pd=95.953% Pd=99.482% Pd=99.843% Pd= 99.9986% at -116 dBm

11. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 11 Co-channel sensing of DTV incumbent DTV TX 118 km DTV protected noise-limited contour 41 dB(uV/m) F(50, 90) Required DTV sensing threshold= -116 dBm to compensate for blockage Sensing CPE Sensing threshold= 24 dB below protected field strength level Sensing threshold: S/N = -21 dB at sensing detector Probability of signal exceeding 17 dB(uV/m) = 99.9986% F(50,1) 460 km F(50,10) 380 km F(10,10) 457 km F(10,1) 544 km F(1,1) 612 km

12. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 12 Collaborative sensing (OR-gate) P LFA : Probability of a local false alarm at a CPE P LMD : Probability of a local misdetection at a CPE P GFA : Probability of a global false alarm at the BS P GMD : Probability of global misdetection at the BS L: number of statistically independent CPEs Any local false alarm causes a global false alarm Any local detection causes a global detection (OR)

13. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 13 Impact of multiple sensors on log-normal curve

14. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 14 Sensing technique performance (I2R covariance absolute value detector) Sampling= 4 ms Pfa= 1 % P detection = 99.843%

15. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 15 Collaborative sensing Special considerations With simple OR gating of sensor reports, the probability of detection will increase rapidly with the number of sensors but Pfa will also tend to increase Pfa for individual sensors can be controlled by repeating sensing before reporting (each sensing window is independent statistically since it works against thermal noise) Data fusion at the base station could be based on a“majority vote” (e.g., 2 out of 6 sensors) from a small number of well selected statistically independent CPEs (e.g., 6 sensors in the same topographic area located at more than 500 m) to provide a high level of probability of detection while keeping Pfa low.

16. doc.: IEEE 802.22-08/0118r0 Submission May 2008 Gerald Chouinard, CRCSlide 16 Collaborative sensing to reduce the amount of false positive results Large number of 'false positive' results are likely to be generated from far away DTV stations due to the proposed low sensing threshold (-116 dBm). This would result in excessive number of unfounded UCS Notifications sent to the BS and unnecessary channel changes. One way to resolve this would be to use cooperative sensing which would provide for equivalent detection probability at a more relaxed sensing threshold. False detection of remote TV stations would then be reduced drastically