1. Wireless network operation in the TV Bands
May 10-14, 2004
Wireless network operation in the TV Bands
Barry O’Mahony
IEEE 802 wireless interim meeting
Garden Grove, CA
10-14 May 2004
Barry (Intel)

2. Overview Background Status TV Band Incumbents
May 10-14, 2004
Overview
Background
Status
TV Band Incumbents
Vacant Channel Device (VCD) operation
Summary
References
Barry (Intel)

3. May 10-14, 2004
Background
FCC 12/2002 released Notice Of Inquiry (NOI) concerning “Additional Spectrum for Unlicensed Devices Below 900 MHz and in the 3 GHz Band”
“below 900 MHz spectrum” in question focused on spectrum where TV broadcasters are primary users.
VHF-L ch. 2-6 (54-72, MHz); VHF-H ch ( MHz); UHF ch ( MHz)
Not channels 52; this spectrum is being re-allocated to non-TV use
Discussed potential of Part 15 modifications that would allow unlicensed devices to use spectrum in locations where it would not cause interference to licensed operations, via cognitive technologies
Intel submitted Comments [refs. 4, 6] and Reply Comments [ref. 5] in support
Authors Waltho, Schiffer, Chartier, Pitsch
Barry (Intel)

4. May 10-14, 2004
Status
14 May 2004 FCC Announces Notice of Proposed Rule Making (NPRM) on unlicensed operation in the TV bands
Two categories of unlicensed devices proposed
Lower-power “personal/portable” devices
e.g.; “Wi-Fi like cards in laptop computers”
Higher-power “fixed/access” devices
Used to provide “a commercial service such as wireless broadband internet access”
Barry (Intel)

5. TV Band incumbents Part 73 – Primary Users Part 74 – Secondary Users
May 10-14, 2004
TV Band incumbents
Part 73 – Primary Users
Full Service TV
Serve ~210 DMA’s
Class A
Low Power Primary Users
Part 74 – Secondary Users
Low-Power TV
LPTV stations – low power “opportunistic” users
Translators & Boosters
TV broadcast auxiliary stations – UHF
Professional wireless microphones
Other
Parts 90 & 20 Mobile Radio Service
One or two TV channels in 13 DMA’s in Ch range (3 in LAX)
Part 15
remote controls, >70 MHz
“Legacy” medical telemetry transmitters, Channels 7-46
Channel 37 reserved for Radio Astronomy
Barry (Intel)

6. 45KW- VHF-L 160KW- VHF-H 1MW - UHF
May 10-14, 2004
TV Broadcast Stations
Type
Full Service
LPTV / Translators /
Boosters
Class A
Spectrum Usage
Primary
Secondary
Year enacted
Analog
1941
Digital
1998
1982
2000
Maximum Radiated Power
316KW – VHF 5MW – UHF
45KW- VHF-L 160KW- VHF-H 1MW - UHF
3KW – VHF 150KW - UHF
300W – VHF 15KW - UHF
Range (miles)
60-80
15-20
# (approx.)
NTSC
1200-DTV
2,200 – LPTV 4,700 - Translators
600
Barry (Intel)

7. TV Broadcast Coverage Predicted service contours Analog – Grade B
May 10-14, 2004
TV Broadcast Coverage
Predicted service contours
Analog – Grade B
Acceptable Picture Quality
“Slightly annoying” on ITU-R subjective scale
Digital – Service Contour
Threshold of Visibility (ToV)
Segment Error Rate (SEV) 1.9  10-4
15 dB SNR
Within these contours, coverage predicted using Longley-Rice propagation model
Stations protected within coverage area
Interference protection - from other transmitters*
Copyright protection - SHVIA
*Class A stations protected at Grade A signal level
Barry (Intel)

8. Field Strengths @ Contour Edge
May 10-14, 2004
Field Contour Edge
Analog Channels
Field Strength, dBμ/m
Grade A Grade B
VHF-L 68 47
VHF-H 71 56
UHF (mid-band) 74 64
Digital Channels
Field Strength, dBμ/m
VHF-L 28
VHF-H 36
UHF (mid-band) 41
Field strengths predicted using F(50,50) [analog] and F(50,90) [digital] curves from Part
Barry (Intel)

9. FCC DTV Planning Factors
May 10-14, 2004
FCC DTV Planning Factors
Planning factor
Symbol
VHF-L
VHF-H
UHF
Mean freq., MHz F 69
194
615
Dipole factor (dBm-dBu) Kd
-111.8
-120.8
-130.8
Dipole factor adjustment Ka
-20  log(615/f)
Thermal noise, dBm Nt
-106.2
Antenna gain, dBd G 4 6 10
Rcv. Antenna
F/B ratio*
Analog
DTV 12 14
Downlead loss, dB L 1 2
Noise figure, dB Ns 7
SNR, dB
C/N 15
Used to compute Service area field strength and interference protection requirements
*used for interference calculations
Barry (Intel)

10. Interference Protection
May 10-14, 2004
Interference Protection
Channel offset
D/U Ratio, dB
Analog into analog
Digital into analog
Analog into DTV
DTV into DTV
Lower adjacent -3
-14
-48
-28
Co-channel
+28
+34
+2→+21*
+15→+23*
Upper adjacent
-13
-17
-49
-26
TV-to-TV co-channel and adjacent channel D/U Ratios:
*Higher ratio required at edge of service area
… Leads to separation distance requirements:
Channel offset
Separation, Km (Zone II)
Analog / analog
Digital / analog
DTV / DTV
Adjacent
> VHF > UHF
<11& >125 – VHF <12& >106 – UHF
<23 & >110 – VHF <24 & >110 – UHF
Co-channel
> VHF > UHF
> VHF > UHF
> VHF > UHF
Note co-located adjacent channel operation permitted for DTV
Barry (Intel)

11. Interference Protection [2]
May 10-14, 2004
Interference Protection [2]
Presumed TV receiver limitations imposed additional requirements in UHF band – “taboo” channels:
Channel Offset
D/U Ratio
Interference mechanism
Analog into analog
DTV into analog
N-8
-32
IF Beat
N-7
-30
-35 “
N-4 
-34
Intermod
N-3
-33
N-2
-26
-24
N+2
-29
-28
N+3
N+4
-23
-25
Half IF & Intermod
N+7
-43
N+8
-41
N+14
Aural Image
N+15 -9
-31
Visual Image
Tuned Circuit
RF Amp
IF Strip
L.O. F MHz
AGC
Tuning Voltage
“Classic” TV front end
Leads to separation requirements for these channels as well
Barry (Intel)

12. Broadcast TV Landscape
May 10-14, 2004
Broadcast TV Landscape
These separation criteria lead to significant white space in most locations
Sample Portland, OR UHF TV Spectrum (as of Jan. ’01)
Barry (Intel)

13. Vacant Channel Devices (VCD)
May 10-14, 2004
Vacant Channel Devices (VCD)
VCDs must operate without causing interference to co-channel and adjacent channel (primarily 1st adjacent) TV;
While at the same time accept interference from adjacent channel TV transmitters
Barry (Intel)

14. Topology of Concern May 10-14, 2004 TV Receiver A Co-channel
Protection area
TV Transmitter A
“Co-channel”
VCD’s
Protected Area A
TV Receiver B
Adjacent channel
Protection area
TV Transmitter B
“Adjacent Channel”
Protected Area B
Barry (Intel)

15. Incumbent TV detection
May 10-14, 2004
Incumbent TV detection
Analog (NTSC)
Visual Carrier 1.25 MHz from band edge
Aural Carrier 4.5 MHz from visual carrier
Chroma subcarrier ~3.58 MHz from visual carrier (precisely  H scan rate)
Digital (ATSC)
8-level Vestigial SideBand (8VSB) modulation
Pilot signal 11.3 dB below full-band power
310 KHz from band edge;
or ~ 332 KHz (precisely 323  H scan rate above lower visual carrier) when co-located with lower-adjacent analog channel
Barry (Intel)

16. Incumbent TV detection [2]
May 10-14, 2004
Incumbent TV detection [2]
Analog SNR at Grade B contour: 34 dB
Digital SNR at service contour: 15 dB
Characteristics of both analog and digital signals should allow reliable detection significantly below level usable for TV reception
e.g., example in (ref. 5), 6 KHz filter on carrier(s) improves sensitivity by 30 dB
Barry (Intel)

17. Interference Protection
May 10-14, 2004
Interference Protection
For wideband unlicensed signals, can use D/U ratios as for DTV
For narrowband signals (≤25 KHz), may use FCC regs. for Wireless Communications Service (WCS) in the Ch band (Part 27.60)
Channel offset
D/U Ratio, dB
Narrow into analog
Wide into analog
Narrow into DTV
Wide into DTV
Lower adjacent
-14
-23
-28
Co-channel
+40
+34
+17
+15→+23
Upper adjacent
-17
-26
Barry (Intel)

18. May 10-14, 2004
VCD Transmit Power
Assuming a vacant channel, VCD TX will depend on D/U ratio for adjacent channels
“worst-case” is separation distance from an adjacent channel receiver located at Grade B contour edge (ref. 4):
Assumes free-space propagation
Higher powers possible in locations where adjacent channel signal is strong
Barry (Intel)

19. Interference from Adjacent TV
May 10-14, 2004
Interference from Adjacent TV
FCC adjacent channel emissions -60 to -88 dB for NTSC, -60 to -78 dB for DTV stations
In 500 KHz BW, relative to peak channel power
Will interfere with VCD signal
e.g.; case for UHF Tx, EIRP = 1MW, 20 dB VCD SNR desired (40 Mbps capacity) (ref. 4):
Barry (Intel)

20. May 10-14, 2004
Summary
Fixed-power VCD operation will allow WLAN-like ranges and bitrates
Adaptive tx control when adjacent signals are stronger will allow longer ranges/higher speeds
High power levels for WMAN-like operation require enhanced incumbent profile detection
Barry (Intel)

21. References CFR Title 47, Parts 20, 27, 73, 74, 90
May 10-14, 2004
References
CFR Title 47, Parts 20, 27, 73, 74, 90
FCC OET Bulletin No. 69, Longley-Rice Methodology for Evaluating TV Coverage and Interference,
FCC Notice Of Inquiry, Additional Spectrum for Unlicensed Devices Below 900 Mhz and in the 3 GHz Band, ET Docket No ,
Comments of Intel Corporation,
Reply Comment of Intel Corporation,
Comments of Intel Corporation,
Barry (Intel)