1. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 1 Aggregate Interference at a DTV Receiver for a Hexagonal Cell Structure IEEE P802.22 Wireless RANs Date: 2007-09-12 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 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 2 Abstract Pervious work has been done to calculate the keep-out region around a DTV transmitter based on a single WRAN interferer signal In this work, we calculate the keep-out region based on the aggregate interference from multiple WRAN BSs Different from [1] –We consider hexagonal cells instead of the circular model –The WRAN cell size is scaled based on the transmit power F(50,10) curves are used to calculate the interference Different from our previous submission [rev0] –F(70,99.9) curves are used to calculate WRAN cell radius –Antenna misalignment is considered

3. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 3 System Model Cell size calculated using ITU F(50,10) curves The DTV protected contour is at 134.2km where the field strength is 41dBu using the F(50,90) propagation curve. –This assumes 1MW ERP DTV transmit power DTV receiver is equipped with a directional antenna with 14dB front-to-back ratio. –Antenna misalignment is considered WRAN BS transmits at P s dBm EIRP All WRANs are transmitting simultaneously on the same DTV channel (frequency reuse one). Only interference from the BS is considered Hexagonal cell structure is assumed for WRAN D/U at DTV receiver is 23dB

4. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 4 margin Primary Tx Primary Rx 1 st tier 2 nd tier D/U Protected contour Secondary system Network Model

5. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 5 DTV Rx Directional Antenna Gain

6. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 6 WRAN Cell Radius Calculation The F(70,99.9) curve is used to calculate cell size as done in the WRAN reference model [2]

7. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 7 Interference Calculation The interference in dBm from the i th WRAN at distance d i is given by where PL() is the path loss in dB using F(50,10) curve, A() is the directional antenna gain at DTV receiver. is the angle of arrival of the interfering signal at the DTV receiver

8. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 8 RiRi didi RpRp Interference Calculation

9. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 9 Interference Calculation Aggregate interference from all WRANs is the sum of all interference sources

10. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 10 0 o antenna misalignment Required Margin x to achieve D/U=23dB versus Transmit Power At EIRP=36dBm, x=16.8km

11. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 11 Required Margin x to achieve D/U=23dB versus Transmit Power At EIRP=36dBm, x=16.8km 10 o antenna misalignment

12. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 12 CPE Average Interference We conjectured before that the BS causes more interference than the CPEs To double check, we calculate the average interference of N CPEs in a single WRAN Base station is located at 16.1 km from protected contour –Same location as BS when considering only one BS interferer CPEs are uniformly dropped around the BS Each CPE transmits at 36dBm EIRP and CPE height is 10m The directional antenna at the CPE is pointed towards its BS 10 4 iterations are used to calculate the average interference

13. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 13 Interference Model and CPE Antenna Gain CPE DTV Rx

14. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 14 CPE Average Interference Results D/U=23dB D/U ration in dB

15. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 15 CPE Interference Summary The number of CPEs required to cause the same level of interference as a single base station is over 65 CPEs In the vast majority of cases the base station interference is much higher than the CPE interference So it is safe to focus our efforts on base station interference

16. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 16 Summary Aggregate interference from WRAN Base Stations is calculated Hexagonal cell structure is considered with frequency reuse one WRAN cell size is scaled based on the transmit power using the F(70,99.9) curve [2] At 36 dBm EIRP –Required keep-out margin is 16.8 km instead of 16.1 km –Aggregate interference is only 0.7 dB more than single WRAN cell interference The results are robust for an antenna misalignment of 10 o The CPE interference is less than the BS interference if less than approximately 70 CPEs transmitting simultaneously

17. doc.: IEEE 802.22-07/0411r1 Submission September 2007 Ahmed Sadek, QualcommSlide 17 References [1] S. Shankar and S. Shellhammer, Aggregate Interference at DTV Receiver, IEEE 802.22-07/254r0, May 2007 [2] G. Chouinard, New WRAN Reference Model, IEEE 22- 05/0002r0, January 2005