doc.: IEEE 802.22-09/0024r0

Submission

FCC Report on Sensing of TV Channels

• IEEE P802.22 Wireless RANs Date: 2009-01-19

January 2009

Victor TawilSlide 1

Name Company Address Phone email

Victor Tawil MSTV 4100 Wisconsin Ave. NW 202-966-1956 Vtawil@mstv.org

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.

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doc.: IEEE 802.22-09/0024r0

Submission

Sensing Concept

• Can spectrum sensing be used to accurately determine whether a TV channel is occupied or vacant? – If device not sensitive enough, device operates on occupied

channel causing interference (Failure A)– If device too sensitive, no channels are available (Failure B)

• Proof of concept must avoid both types of failures

Victor TawilSlide 2

January 2009

See, for example, Fundamental Design Tradeoffs in Cognitive Radio Systems or Fundamental Limits on Detection in Low SNR Under Noise Uncertainty by Department of Electrical

Engineering and Computer Science, University of California at Berkley

doc.: IEEE 802.22-09/0024r0

Submission

Latest FCC Field Testing Program(Sensing)

Victor TawilSlide 3

January 2009

Victor Tawil

• Four Devices Field Tested – Motorola (Geolocation, DTV-only sensing)

– Philips (DTV, NTSC and microphone sensing)

– Adaptrum (DTV and NTSC sensing, transmit capability)

– I2R (DTV, NTSC and microphone sensing)

doc.: IEEE 802.22-09/0024r0

Submission

Field Test Program

• TV “Sensing” Tests Conducted at 9 Locations in Washington/Baltimore Area– 5 outdoor locations (2 suburban + 3 rural)– 4 indoor locations (FCC + 3 homes)

• Cable Interference Tests/Observations Conducted at 2 of the 3 homes – Adaptrum transmit capability used

• Microphone “Sensing” Tests Conducted at 2 Venues– FEDEX Field (Redskin football game)– Majestic Theater (Phantom Broadway show)– Only Philips and I2R device tested

January 2009

Victor TawilSlide 4

doc.: IEEE 802.22-09/0024r0

Submission

TV Sensing Tests

January 2009

Victor TawilSlide 5

• Lots of data• How to measure accuracy of sensing• Define “Sensing Error Rate”

– Number of errors the device makes in determining whether a channel is vacant or occupied/total number of channels over which “sensing” takes place

doc.: IEEE 802.22-09/0024r0

Submission

MSTV Observations of FCC Sensing Data

January 2009

Victor TawilSlide 6

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Submission

January 2009

Victor TawilSlide 7

CH Signal Type

(Database)

Within Service

Contour? (Y/N)

Viewable? (Y/N)

Signal Type

(Measured)

Measured Power Level (dBm)

Occupied (O) & Available (A) Channels Reported by

WSD

L1/ S1

L1/ S2

L2/ S1

L2/ S2

21 - N N - < -71.0 O O O O 22 NTSC Y Y NTSC -39.4 O O O O 23 NTSC N N ATSC < -67.3 O O O O

24 NTSC Y Y NTSC -28.0 O O O O 25 NTSC N N NTSC -88.6 O O O O 26 NTSC Y N NTSC -79.5 O O O O 27 ATSC Y Y ATSC -65.4 O O O O 28 ATSC N N NTSC -90.0 O O O O 29 ATSC Y Y ATSC -47.9 O O O O

30 ATSC N N

ATSC < -69.8 O O O O ATSC N N

31 NTSC N N - - O O O O 32 NTSC Y Y NTSC -73.4 O O O O 33 ATSC Y Y ATSC -81.6 O O O O 34 ATSC Y Y ATSC -59.1 O O O O 35 ATSC Y Y ATSC -62.6 O O O O

36 ATSC Y Y ATSC -62.2 O O O O 37 ATSC -16.0 O O O O 38 ATSC Y Y ATSC -65.3 O O O O 39 ATSC Y N ATSC -20.4 O O O O 40 ATSC Y Y ATSC -44.7 O O O O 41 ATSC Y Y ATSC -43.9 O O O O 42 ATSC Y Y ATSC -72.7 O O O O

43 NTSC N Y

NTSC -

O O O O ATSC N N

44 - - - - -23.0 O A O A 45 NTSC Y Y NTSC -20.7 O O O O 46 ATSC Y Y ATSC -78.7 O O O O 47 ATSC N N NTSC < -69.2 O O O O 48 ATSC Y N ATSC -93.1 O O O O 49 NTSC N N NTSC -66.1 O O O O 50 NTSC Y Y NTSC -69.1 O O O O

51 ATSC Y N NTSC < -71.0 O O O O

doc.: IEEE 802.22-09/0024r0

Submission

Cable TV Test Observations

January 2009

Victor TawilSlide 8

• Interference from White Space Device transmissions to cable television was tested at two residences

• Results showed interference to both analog and digital cable service– In one home, analog interferences occurred at distance of

about 10 feet and thru interior wall – Transmit power had to be reduced to less than 3 mW to

eliminate interference to analog TV and about 5 mW to eliminate interference to digital cable

– At second home, transmit power had to be reduced to less than 10 mW to eliminate interference

• Results fully consistent with earlier FCC testing

doc.: IEEE 802.22-09/0024r0

Submission

Wireless Microphone

January 2009

Victor TawilSlide 9

• FedEx Field • Microphones on 11 TV channels

– 21, 23, 27, 31, 33, 34, 43, 44, 45, 47, and 49 • Four Test Locations

– Field Level, Tailgate Club, 400 Level and Press Box• Philips device

– Detected one microphone channel at field level and reported all other channels occupied with microphones off

– All channels occupied at all other locations• I2R device

– Detected microphone channels about 50% of the time in most locations, about 20% in worst location (Tailgate club)

doc.: IEEE 802.22-09/0024r0

Submission

FCC Report, October 2008:Field Test Conclusions

• Several tests were performed with DTV signals present in adjacent channels. These tests showed that in the presence of moderate-to-strong signals in a first adjacent channel, the detection threshold sensitivity of all of the devices was severely impacted. For some of the devices, the degradation in the detection sensitivity was as much as 60-70 dB. In some cases, the degradation was such that the detection threshold could not be measured. This could impact significantly the ability of the devices to reliably detect TV signals within stations’ service areas.

January 2009

Victor TawilSlide 10

doc.: IEEE 802.22-09/0024r0

Submission

Prototype WSD

Detection Thresholds in the Presence of DTV-Occupied Adjacent Channels (dBm)

N+1 N-1 N+2 N-2 H M L H M L H M L H M L

Adaptrum A -108 -120 -100 A A -108 -120 -120 -105 -119 -120 I2R -97 -117 -119 A A -117 -118 -118 -118 -118 -118 -117

Microsoft -67 -110 A B B B -76 -118 -120 B B B Motorola -52 -97 -114 -47 -68 -109 -79 -115 -114 -76 -115 -114 Motorola

(w/modification) -102 -111 -110 -73 -98 -110 -96 -112 -112 -96 -112 -112

Philips A A -122 A A -122 A -122 -124 A A -123 Notes: H = High adjacent signal level (-28 dBm); M = Moderate adjacent signal level (-53 dBm); L = Low adjacent signal level (-68 dBm). A = Insufficient receiver selectivity and/or receiver desensitization prevented collection of meaningful data. B = Device malfunction prevented collection of data.

FCC Report, October 2008: Field Test Adjacent Channel Conclusions

January 2009

Victor TawilSlide 11

doc.: IEEE 802.22-09/0024r0

Submission

FCC Report, October 2008:Field Test Conclusions

• Wireless microphone sensing tests were performed using the I2R and Philips devices at two field locations. The tests were conducted first with microphones off, and then turned on, in pre-determined channels to determine if the devices could sense the presence of wireless microphones. At both sites and all the test locations, the Philips device reported all the channels on which the microphones were designated to transmit as occupied whether the microphone was transmitting or not. The I2R device indicated several channels as available even when the microphones were on

January 2009

Victor TawilSlide 12

doc.: IEEE 802.22-09/0024r0

Submission

Proposed Recommendation

• Based on the FCC data in the report, Sensing did not properly detect incumbents, especially with the presence of false alarm. Need improvements

• Recommend that FCC defers from mandating TV sensing and make it optional until sensing improvements are achieved

January 2009

Victor TawilSlide 13

doc.: IEEE 802.22-09/0024r0

Submission

References

• Office of Engineering and Technology “TV White Space Phase II Test Report.” October 15, 2008

January 2009

Victor TawilSlide 14