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Managing Interference Between Television and Wireless Services

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Released: January 29, 2014

PUBLIC NOTICE

Federal Communications Commission

News Media Information 202 / 418-0500

445 12th St., S.W.

Internet: http://www.fcc.gov

Washington, D.C. 20554

TTY: 1-888-835-5322

DA 14-98

Release Date: January 29, 2014

OFFICE OF ENGINEERING AND TECHNOLOGY

SEEKS TO SUPPLEMENT THE INCENTIVE AUCTION PROCEEDING RECORD

REGARDING POTENTIAL INTERFERENCE BETWEEN
BROADCAST TELEVISION AND WIRELESS SERVICES

ET Docket No. 14-14

GN Docket No. 12-268

Comments Date: February 28, 2014

The FCC’s Office of Engineering and Technology (OET) seeks to supplement the record in the
incentive auction proceeding by inviting comment on a methodology for predicting potential interference
between broadcast television and licensed wireless services. In the Broadcast Television Incentive
Auction NPRM
, the Commission sought public comment on creating a 600 MHz wireless band plan f rom
the spectrum made available for flexible use through the broadcast television incentive auction. 1 The
Commission expressed a strong interest in establishing a band plan framework that is flexible enough to
accommodate market variation (i.e., offering varying amounts of spectrum in different geographic
locations, depending on the spectrum recovered2) to maximize the amount of spectrum repurposed.
In response to the NPRM and the 600 MHz Band Plan Supplemental Public Notice, a number of
commenters raised concerns about co-channel and adjacent-channel interference between television and
wireless services in nearby markets as a result of accommodating market variation. 3 Some commenters

1
Expanding the Economic and Innovation Opportunities of Spectrum Through Incentive Auctions, Notice of
Proposed Rulemaking, 27 FCC Rcd 12357, 12401-27, paras. 123-98 (2012) (NPRM).
2
NPRM, 27 FCC Rcd at 12401, para. 123-24. See Wireless Telecommunications Bureau Seeks to Supplement the
Record on the 600 MHz Band Plan,
Public Notice, 28 FCC Rcd 7414 (May 17, 2013) (600 MHz Band
Supplemental Public Notice
) (seeking further comment on how certain band plan approaches can best address the
potential for market variation).
3
Alcatel-Lucent Supplemental Comments at 6-7; Block Stations Supplemental Comments 3-4; Sinclair
Supplemental Comments 2; AT&T Comments 4-7 27-28, Exh A 15, 32-33; T-Mobile Supplemental Comments
17 n.32, Supplemental Reply Comments 13-14; Qualcomm Supplemental Comments 14, 17; US Cellular
Supplemental Comments 3; Cohen, Dippell and Everist Supplemental Comments 1-2; CTIA Supplemental Reply
Comments 8-9; Ericsson Supplemental Comments 9; Free Press Supplemental Reply Comments 9; HBC
(continued….)

proposed separation distances between the two services. The most common approach commenters
propose is to use a pre-defined separation distance between TV and mobile service areas.4 Commenters
proposed distances that varied significantly—ranging from 100 kilometers to 500 kilometers—and
generally provided limited technical analysis in support of these proposals.
The Commission has rules in place to control co-channel and adjacent-channel interference from
mobile operations to digital television (DTV) reception for the 470–512 MHz (“T-Band”) and 700 MHz
bands.5 However, these rules do not have direct applicability in the incentive auction. The rules were
addressing situations where wireless licensees could design their systems to avoid causing interference to
television reception by techniques such as reducing power and antenna height or for a transitional period
during which relatively few wireless facilities would be constructed. In the “T-band,” the pertinent
wireless systems are conventional land mobile facilities that do not utilize cellular architectures used for
commercial wireless service. In the case of 700 MHz, the rules were intended as an interim measure for
spectrum that was eventually going to be cleared of TV broadcasting. Further, the present rules do not
address interference from DTV into wireless systems.

Potential Interference Scenarios

Four scenarios exist that could result in interference between broadcast television and licensed
wireless services, depending upon the geographic locations and spectrum where DTV operation is
permitted relative to wireless operation under the 600 MHz band plan that the Commission ultimately
adopts. These scenarios are illustrated in Figure 1 and are discussed below:
(Continued from previous page)
Supplemental Reply Comments 3-5; NAB Reply Comments 12-18, Supplemental Comments 2-6, Supplemental
Reply Comments 3-8; WISPA Supplemental Reply Comments 8.
4
Qualcomm Supplemental Comments at 14 (“the distances at which a full power TV broadcast signal will
interfere with mobile broadband uplink operations is . . . approximately 500 km (or 310 miles).”); Letter from
Rick Kaplan, NAB, to Marlene H. Dortch, Secretary, FCC, (filed Jul. 10, 2013) (interference from TV
transmission to base station receiver is 225 to 375 km); AT&T Supplemental Comments at 4 (“separation
distances between TV transmitters and wireless base station receivers would generally need to be in the range of
more than 200 kilometers in order to avoid harmful co-channel interference to mobile base station receivers”);
Verizon Supplemental Comments at 8 (geographic separation zones of 200-400 kilometers would likely be
required to mitigate [co-channel] interference from broadcaster transmitters into wireless base stations). See also
AT&T Comments 4-6; AT&T Ex Parte 4-14; T-Mobile Ex Parte (Supplement by Roberson and Associates,
LLC) 1-17; NAB Ex Parte 1-41; CEA Ex Parte 1-58.
5
See 47 C.F.R. §§ 90.307 and 27.60
2

Figure 1. Interference scenarios
(1) DTV transmitter-into-wireless base station (uplink) interference. Based on our calculations
and the comments submitted into the record, this case tends to lead to the largest required separation
distances because both the base station receive antenna and the DTV transmitting antenna are often
located well above the surrounding terrain, potentially creating a line-of-sight path between them.
(2) DTV transmitter-into-wireless user equipment (downlink) interference. This case is not likely
to require separation distances as large as Case 1 because the wireless user equipment (UE) typically
operates near ground level or in buildings where propagation conditions including clutter or other losses
are likely to greatly reduce the strength of distant co-channel DTV signals. We note that there is a
potential for interference to UE receivers from nearby adjacent-channel DTV transmissions because the
off-channel rejection of UE receivers is often limited compared with base station receivers.
(3) Wireless base station (downlink)-into-DTV receiver interference. Although the separation
distance may be relatively large between a wireless base station and a co-channel DTV transmitter
operating in the base station’s uplink spectrum (Case 1), the distance from a wireless base station to DTV
receivers at the edge of a DTV station’s service contour would be much less. In addition, DTV reception,
especially at the edge of a DTV station’s service contour, would likely use outdoor antennas at rooftop
levels. This would tend to increase the likelihood that a DTV receiver could experience interference from
a wireless base station. A separate analysis that factors in these conditions needs to be performed relative
to the potential for co-channel and adjacent-channel harmful interference that could be caused to DTV
reception by the base station downlink transmitter.
(4) Wireless user equipment (uplink)-into-DTV receiver interference. To avoid interference with
the associated uplink spectrum, base station receivers require a relatively large separation distance from
3

co-channel DTV transmitters (Case 1). Therefore, we believe that there is no significant risk of co-
channel interference to DTV reception from UE transmitters. However, adjacent-channel interference to
DTV receivers may result when wireless user equipment operates in close proximity to DTV receivers.

Potential Solutions

We are concerned that prescribing a pre-defined separation distance as proposed by some
commenters may be spectrally inefficient and overly conservative. Specifically, this approach lumps
together all of the above cases and applies separation distances based on a worst case scenario without
considering factors such as the actual technical characteristics of the DTV transmitter (e.g., power level,
antenna height, and radiation patterns), terrain variability and the density of population in areas predicted
to receive interference. Such an approach also fails to account for technologies and techniques that
wireless licensees might employ to mitigate potential interference, such as antenna characteristics and
resource block provisioning.
Accordingly, we invite comment on an alternative methodology that could enable the
Commission to accommodate market variation in a more spectrally efficient manner than that proposed
by various commenters. This alternative methodology uses established planning factors and industry
standards to define thresholds of coverage and interference, suggests typical engineering specifications in
the absence of industry standards, and applies commonly used protocols, databases, and propagation
models to create a predictive model that can be run on a computer. This methodology is described in
detail in the appendix to this Public Notice.

Specific Topics for Comment

OET seeks comment on the methodology for predicting potential interference between television
and wireless services, described in the attached appendix (OET Methodology). Specifically, OET seeks
comment on whether this methodology can provide greater accuracy than a generic separation distance
(pre-defined radius) in predicting potential harmful interference between services, thereby enabling the
Commission to repurpose more spectrum by accommodating market variation.
OET seeks comment on whether interference to and from analog television stations should be
considered and what assumptions and parameters would be appropriate for studies involving such
stations. OET also invites comment on a number of specific topics as discussed below.
General Methodology
While the OET Methodology may potentially improve the efficiency of spectrum use compared
to the use of fixed separation distances, OET recognizes that it also increases the complexity of the
analysis required. Would this methodology strike a more appropriate balance between efficiency of
spectrum use and the technical analysis required in the incentive auction than fixed co-channel and
adjacent channel separation distances? Are there variations of the OET methodology or other approaches
that would better address these concerns for interference protection and spectrum efficiency?
Methodology to Determine DTV Interference to Wireless
We seek comment on the approach described to determine wireless license impairments. Are
there other methods to determine wireless market impairments in the 600 MHz band?
4

Methodology to Determine Wireless Interference to DTV
We seek comment on the approach described to determine interference to DTV stations. Should
we instead set one or more simple separation distance requirements? Will calculation of the D/U ratio
values on a 2-kilometer grid with base stations spaced uniformly at 10-kilometer intervals provide
sufficient resolution when determining possible interference?
We request comment on the extent of predicted interference to DTV reception based on our grid-
based approach. Should we define areas within a wireless market, such as county boundaries, where if
the operations of any given hypothetical wireless base station cause predicted interference to a DTV
station, regardless of population impacted, we would infer that all wireless operation in that area would
cause interference to that station?
Technical Assumptions
The OET methodology makes certain assumptions about the characteristics of DTV transmission
facilities and DTV receivers as well as wireless transmission facilities and receivers based mostly on
existing industry standards and available technical data. For digital television, the DTV planning factors6
underlie the definition of service. Receiver performance expectations were used to develop the
interference criteria in the Commission’s rules.7 Because 600 MHz wireless services are expected to be
noise-like and studies have shown that noise-like signals have interference potential nearly identical to
ATSC digital television,8 we believe that the existing DTV protection criteria can be applied with some
adjustments for frequency offsets as discussed below. Similarly, for wireless systems operating at 600
MHz, industry standards9 define reception thresholds and provide receiver performance criteria. The
methodology assumes a uniform distribution of wireless base stations. We seek comment on whether
these assumptions are appropriate. We also seek comment on whether the criteria for service and
interference are appropriate for use in a predictive model to establish locations of likely interference
between TV broadcast and wireless services operating co-channel or adjacent-channel.
One significant issue that will impact the potential for co-channel and adjacent-channel
interference between TV broadcast and wireless services is the varying degree of spectral overlap that
will exist between the two services. Because the Commission has proposed to repurpose six megahertz
TV broadcast channels as five megahertz wireless blocks,10 a single television channel may overlap two
wireless channels in a nearby wireless license area. The difference in channel bandwidth (six vs. five
megahertz) means that the channels will not perfectly align, and the different amounts of spectral overlap
suggest that protection requirements should reflect the variation.

6
See OET Bulletin No. 69 (OET-69), Longley-Rice Methodology for Evaluating TV Coverage and Interference,
Feb. 6, 2004, Table 3.
7
See OET-69, Table 5A.
8
See Stephen R. Martin, “Interference Rejection Thresholds of Consumer Digital Television Receivers Available
in 2005 and 2006,” FCC/OET Report 07-TR-1003, March 30, 2007. See also, “Tests of ATSC 8-VSB Reception
Performance of Consumer Digital Television Receivers Available in 2005,” FCC/OET Report TR-05-1017
November 2, 2005.
9
See 3GPP Technical Specification 36.101, Evolved Universal Terrestrial Radio Access (E-UTRA); User
Equipment (UE) radio transmission and reception
, available at http://www.3gpp.org/DynaReport/36101.htm.
See also 3GPP Technical Specification 36.104, Evolved Universal Terrestrial Radio Access (E-UTRA); Base
Station (BS) radio transmission and reception
, available at http://www.3gpp.org/DynaReport/36104.htm.
10 See NPRM 27 FCC Rcd at 12403-04, paras. 127-130.
5

Figure 2 provides an example where the spectral overlap between potential wireless Block E and
TV Channel 47 is one megahertz, meaning that one megahertz of TV Channel 47 is co-channel with
Block E. On the other hand, the spectral overlap between potential wireless Block D and TV Channel 47
is -4 megahertz, because there are four megahertz of frequency separation between the respective channel
edges. We invite comment on whether the total power in the spectral overlap should be used in assessing
interference. Will these assumptions be applicable if licensees aggregate multiple spectrum blocks to
provide wider bandwidth channels? How should interference power be accounted for in cases where
there is a potential for interference from two adjacent wireless blocks?
DTV:
………. TV47 TV48 TV49 TV50 TV51
Wireless:
………………. E
D
C
B
A
Figure 2. 6 MHz DTV and 5 MHz Wireless channel alignment
For predicting television coverage and interference over large distances, the FCC has often
applied the “Longley-Rice” radio propagation model.11 Although the FCC has not previously applied this
model in a wireless or inter-service context, its use may be appropriate for predicting propagation losses
over the range of distances and antenna heights involved in three of the four scenarios described above.12
We seek comment on whether applying Longley-Rice is an appropriate propagation model for some or all
of the four interference scenarios described above, and we seek suggestions for specific alternative
propagation models. We also seek comment on the appropriate configuration parameters to use in each
case, as well as whether the consideration of morphology (clutter) is appropriate and appropriate clutter
losses for interference cases involving the user equipment. We also seek comment on the appropriate
statistical parameters for the Longley-Rice model, in particular the use of F(50, 50) when examining DTV
field strength at the wireless receiver. We also request suggestions of alternative methods for modeling
the propagation of signals from mobile devices to DTV receivers.

11 OET Bulletin No. 69 (Feb. 6, 2004), available at
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet69/oet69.pdf.
OET Bulletin No. 72 (July 2, 2002), available at
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet72/oet72.pdf.
OET Bulletin No. 73 (Nov. 23, 2010), available at
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet73/oet73.pdf.
See also Hufford, G.A., Longley, A.G., and Kissick, W.A., “A Guide to the Use of the ITS Irregular Terrain
Model in the Area Prediction Mode,” NTIA Report 82-100, U.S. Department of Commerce, April 1982.
12 Case 4 (UE-into-DTV interference) is expected involve distances of less than one kilometer up to a few
kilometers and the Longley-Rice model may not be suitable for such short distances. See Daniel, W. and Wong,
H., “Propagation in Suburban Areas at Distances less than Ten Miles,” FCC/OET TM 91-1, Federal
Communications Commission, Office of Engineering and Technology, January 25, 1991.
6

Additional Topics

Further, we invite comment on how to use the information derived from the OET Methodology in
the context of the repacking of broadcasters.
The OET Methodology addresses adjacent channel interference. Most commenters have focused
their concerns on co-channel interference more than adjacent-channel interference, perhaps due to
assumptions that guard bands would be used to prevent adjacent-channel interference. In the case of
market variation, however, guard bands could be slightly different in each market, creating the potential
for interference between DTV and wireless services that otherwise would not exist. We invite comment
on the impact of adjacent-channel interference constraints in the context of market variation.
The OET Methodology provides a technique for calculating the predicted interference to DTV
service, but does not address what limits should be applied to such interference, whether wireless license
areas should be auctioned if predicted interference to wireless service exceeds some threshold, or whether
interference from wireless facilities should be accounted for in calculating a DTV station’s service area
and/or population served. Should predicted interference from wireless facilities to a DTV station be
ignored if it does not affect the population within the station’s service area? Would it be appropriate to
set a low threshold for acceptable interference from wireless to DTV service, such as allowing a wireless
licensee to reduce the coverage of a DTV station by no more than 0.1% of its population served? Would
it be sufficient to consider only interference from base station facilities, or should interference from
wireless user equipment also be considered?
The OET Methodology provides a technique for calculating the predicted interference to wireless.
We also seek comment on how this information should be made available to bidders in the forward
auction. Should the Commission set predefined impairment thresholds, e.g., where less than 5% of the
market population may potentially experience interference, should we consider this wireless market to be
effectively unimpaired? What should the thresholds for specifying impairments be?
This Public Notice and the attached appendix relate to the technical aspects of the repacking
process and auction design. We emphasize that nothing in this Public Notice is intended to signal any
final staff recommendation to the Commission relative to the prospective band plan or other issues raised
in the incentive auctions proceeding, such as whether to make spectrum available only on a paired basis,
provide supplemental downlink spectrum or permit time-division duplex operation. Further, although we
seek input on the four interference cases discussed above, we note that we may not encounter each of
those scenarios in practice, depending on the band plan and repacking methodology the Commission
ultimately adopts. Rather, this Public Notice seeks only to expand the record by seeking comment on a
potential method for minimizing the potential for interference between TV broadcast and wireless
services operating in different markets on the same or adjacent spectrum.
The Incentive Auction Task Force intends to host a Workshop/Webinar on February 21 to discuss this
methodology for predicting potential interference between television and wireless mobile broadband
services. At that time, Task Force staff will also respond to questions and comments about the details of
this Public Notice and the attached Technical Appendix. More information, including how to participate,
will be released prior to the Workshop/Webinar. Details about the Workshop/Webinar will be released
by Public Notice and on the LEARN website at: http://www.fcc.gov/learn.
7

This Public Notice is being issued pursuant to section 0.31 of the Commission’s rules by the
Office of Engineering and Technology, a member of the Incentive Auction Task Force.13 Comments may
be filed using the Commission’s Electronic Comment Filing System (ECFS). See Electronic Filing of
Documents in Rulemaking Proceedings, 63 FR 24121 (1998).

Electronic Filers: Comments may be filed electronically using the Internet by accessing
the ECFS: http://fjallfoss.fcc.gov/ecfs2/.

Paper Filers: Parties who choose to file by paper must file an original and one copy of
each filing. If more than one docket or rulemaking number appears in the caption of this proceeding, filers
must submit two additional copies for each additional docket or rulemaking number.

Filings can be sent by hand or messenger delivery, by commercial overnight courier, or
by first-class or overnight U.S. Postal Service mail. All filings must be addressed to the Commission’s
Secretary, Office of the Secretary, Federal Communications Commission.

All hand-delivered or messenger-delivered paper filings for the Commission’s Secretary
must be delivered to FCC Headquarters at 445 12th St., SW, Room TW-A325, Washington, DC 20554.
The filing hours are 8:00 a.m. to 7:00 p.m. All hand deliveries must be held together with rubber bands or
fasteners. Any envelopes and boxes must be disposed of before entering the building.

Commercial overnight mail (other than U.S. Postal Service Express Mail and Priority
Mail) must be sent to 9300 East Hampton Drive, Capitol Heights, MD 20743.

U.S. Postal Service first-class, Express, and Priority mail must be addressed to 445 12th
Street, SW, Washington DC 20554.
People with Disabilities: To request materials in accessible formats for people with disabilities
(braille, large print, electronic files, audio format), send an e-mail to fcc504@fcc.gov or call the
Consumer & Governmental Affairs Bureau at 202-418-0530 (voice), 202-418-0432 (tty).
The proceeding this Notice initiates shall be treated as a “permit-but-disclose” proceeding in
accordance with the Commission’s ex parte rules.14 Persons making ex parte presentations must file a
copy of any written presentation or a memorandum summarizing any oral presentation within two
business days after the presentation (unless a different deadline applicable to the Sunshine period applies).
Persons making oral ex parte presentations are reminded that memoranda summarizing the presentation
must (1) list all persons attending or otherwise participating in the meeting at which the ex parte
presentation was made, and (2) summarize all data presented and arguments made during the
presentation. If the presentation consisted in whole or in part of the presentation of data or arguments
already reflected in the presenter’s written comments, memoranda or other filings in the proceeding, the
presenter may provide citations to such data or arguments in his or her prior comments, memoranda, or
other filings (specifying the relevant page and/or paragraph numbers where such data or arguments can be
found) in lieu of summarizing them in the memorandum. Documents shown or given to Commission
staff during ex parte meetings are deemed to be written ex parte presentations and must be filed
consistent with rule 1.1206(b). In proceedings governed by rule 1.49(f) or for which the Commission has

13 47 C.F.R. § 0.31.
14 47 C.F.R. §§ 1.1200 et seq.
8

made available a method of electronic filing, written ex parte presentations and memoranda summarizing
oral ex parte presentations, and all attachments thereto, must be filed through the electronic comment
filing system available for that proceeding, and must be filed in their native format (e.g., .doc, .xml, .ppt,
searchable .pdf). Participants in this proceeding should familiarize themselves with the Commission’s ex
parte
rules.
For further information, contact Cecilia Sulhoff at cecilia.sulhoff@fcc.gov.
– FCC –
9

APPENDIX

METHODOLOGY FOR

PREDICTING POTENTIAL INTERFERENCE BETWEEN

TELEVISION AND WIRELESS MOBILE BROADBAND SERVICES

Introduction

This appendix sets forth a methodology for predicting interference between broadcast television
and wireless services when co-channel or on adjacent channels. Generally, co-channel interference
between wireless services (base stations or mobile user equipment (UE)) and broadcast television
becomes unlikely if these services are geographically separated by a predetermined distance. Likewise,
adjacent-channel interference becomes unlikely at a lesser distance than for the co-channel case,
depending on the frequency separation between the television channel and the wireless block. The
methodology described in this appendix may be used to predict whether interference is expected to occur
at a location and thereby establish the necessary separation distances in a deterministic way.
The methodology described herein uses the Institute of Telecommunications Science’s Irregular
Terrain Model (Longley-Rice model) for predicting radio signal propagation losses, established planning
factors and industry standards to define thresholds of coverage and interference, suggests typical technical
specifications in the absence of industry standards, and generally applies commonly used protocols,
databases, and propagation models to describe a predictive methodology that can be run on a computer.
For broadcast television, we assume use of the Advanced Television Systems Committee’s (ATSC)
Digital Television (DTV) Standard,1 although it is possible, especially across international borders, that
the National Television Systems Committee (NTSC) analog Television (TV) standard may also be used.2
For wireless, we assume use of the 3rd Generation Partnership Project (3GPP) Long-Term Evolution
(LTE) standard.3 We use the Longley-Rice radio model, which predicts field strength at receive points

1
See 47 C.F.R. § 73.682(d).
2
For analog NTSC television transmission standards, see, e.g., 28 FR 13676. Domestically, low-power television
stations, including Class A and television translators, are the only remaining over-the-air broadcast television
service permitted to transmit analog signals. However, they are required to cease analog operation and convert
to digital by September 1, 2015. See Amendment of Parts 73 and 74 of the Commission’s Rules to Establish
Rules for Digital Low Power Television, Television Translator, and Television Booster Stations and to Amend
Rules for Digital Class A Television Stations, Second Report and Order, 26 FCC Rcd 10732 (2011).
3
Specifically, we reference the radio access layer of the 3GPP LTE technical specification, Release 10. See
Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and reception,
3GPP specification detail, http://www.3gpp.org/DynaReport/36104.htm, Version 10.11.0. See also Evolved
Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception, 3GPP
specification detail, http://www.3gpp.org/DynaReport/36101.htm, Version 10.12.0. For a synopsis of LTE
deployments to date see, e.g.,
http://www.4gamericas.org/index.cfm?fuseaction=pressreleasedisplay&pressreleaseid=4746.
10

based on the elevation profile of terrain between the transmitter and each specific reception point.4
Predictions are made either over a large area (described as a 2-kilometer grid of calculation cells) or at
specific locations, depending upon whether the model is configured to use its broadcast or individual
location mode. The methodology described in this appendix deals primarily with predictions over large
areas using the broadcast mode.

Overview of Methodology

There are four interference scenarios if digital broadcast television (DTV) and wireless services
are permitted in the 600 MHz band. These scenarios are listed below and are illustrated in Figure A-1.

Case 1: DTV Transmitter into Wireless Uplink (base station receiver)

Case 2: DTV Transmitter into Wireless Downlink (UE receiver)

Case 3: Base Station Transmitter (downlink) into DTV Receiver

Case 4: User Equipment Transmitter (uplink) into DTV Receiver
Figure A-1. Market variation interference scenarios

4
The Commission has used the Longley Rice propagation model in several contexts including OET Bulletin Nos.
69, 72 and 73.
11

Spectral Overlap. A significant issue that will impact the potential for co-channel and adjacent-
channel interference between TV broadcast and wireless services is the varying degree of spectral overlap
that may exist between the two services in the new 600 MHz band. Because the broadcast television
channels to be reclaimed are six megahertz wide and the Commission has proposed to repurpose them as
five megahertz wireless blocks,5 a single television channel may overlap two wireless blocks in a nearby
wireless license area. The difference in channel bandwidth (six vs. five megahertz) means that the
channels and blocks do not perfectly align, and the different amounts of spectral overlap suggest that
protection requirements should reflect the variation.
Figure A-2 provides an example of market variation between two wireless markets where the
amount of wireless spectrum in Wireless Market 2 is reduced in order to assign TV channels 47 and 48 to
television broadcast in that market. Figure A-2 also shows an example guard band between the DTV
service and wireless service in Wireless Market 2.6 The spectral overlap between wireless Block E in
Market 1 and TV Channel 47 in Wireless Market 2 is one megahertz, meaning that one megahertz of TV
Channel 47 is co-channel with Block E. On the other hand, the spectral overlap between potential
wireless Block D in Market 1 and TV Channel 47 in Wireless Market 2 is -4 megahertz, because there are
four megahertz of frequency separation between the respective channel edges. In this example, the guard
band is eight megahertz in Market 2 between TV channel 48 and wireless block B, but across markets
there is sufficient distance separation between Market 1 and Market 2 such that co - and adjacent-channel
interference is minimized.
Figure A-2. 6 MHz TV channel and 5 MHz wireless block alignment
We define as co-channel those TV channel/wireless block pairs having frequency overlaps of +5
MHz to +1 MHz,7 and to define adjacent-channel relationships as those TV channel/wireless block pairs

5
See NPRM 27 FCC Rcd at 12403-04, paras. 127-130.
6
See NPRM 27 FCC Rcd at 12420, para. 176.
7
Assuming a 5 MHz wireless block bandwidth, the entire 5 MHz wireless signal may overlap co-channel with the
6 MHz passband of a TV receiver. However, we recognize that multiple contiguous wireless spectrum blocks
might be licensed to a single network operator. For co-channel wireless interference into DTV, where the
overlap is +5 MHz, we assume in Table 10 that the interference power in the wireless block is spread across
contiguous adjacent 5 MHz wireless blocks affecting one 6 MHz TV channel. For co-channel DTV into
wireless, we assume that the susceptibility to interference of wireless systems having greater bandwidths are
similar to 5 MHz systems, because the applicable 3GPP Technical Specifications shown in Table 5 and used to
(continued….)
12

with frequency overlaps of 0 MHz to -5 MHz.8 Further, we examine all TV channel/wireless block
overlaps from +5 MHz to -5 MHz for all cases, in one megahertz increments, considering both DTV
interference into wireless as well as wireless interference into DTV.
Field Strength and D/U Interference Limits as a Function of Spectral Overlap. To determine
potential wireless license impairments, our methodology sets field strength limits at the wireless receive
antenna as a function of the amount of spectral overlap between the DTV transmit channel and the
wireless receive channel. For example, a DTV station with an overlap of -5 MHz (i.e., adjacent-channel
operation) is assumed to be able to produce a higher maximum field strength at the victim receive antenna
without causing harmful interference than would a DTV station with an overlap of +5 MHz (i.e., co-
channel operation).
Similarly, to assess potential interference to a DTV receiver, our methodology uses the co-
channel D/U ratio specified in OET Bulletin No. 699 for a +5 MHz overlap and adjusts the D/U
requirement based on the extent of overlap between the wireless transmitter channel and the DTV
receiver channel. We account for the possibility that a wireless licensee may aggregate several 5 MHz
channel blocks in Table 5, Table 6, and Table 10 below, as described in footnote 7.
Methodology to Determine DTV Interference to Wireless. Cases 1 and 2 involve interference
caused by a co- or adjacent-channel DTV transmitter to a wireless base station or user equipment located
within the wireless license area. To determine areas of possible wireless interference (wireless service
impairments) we divide the wireless license area into a 2-kilometer grid and calculate field strength levels
at each grid point for each DTV facility that is assigned a co- or adjacent-channel frequency within
approximately 500 km.10 The predicted field strength at each grid point is then compared with the
appropriate interference threshold field strength.
Figure A-3 illustrates how the spectral overlaps and field strength interference limits can be used
to determine potential market impairments. In the illustration, two DTV facilities are assigned co- or
adjacent-channel to wireless Block D. From Figure A-2 we see that the edge of TV Channel 47 is 4 MHz
from the D block (overlap = -4 MHz) and TV channel 48 overlaps the D block by 2 MHz (overlap = +2
MHz).
(Continued from previous page)
derive the uplink row of Table 7 are similar among 5, 10, 15 and 20 MHz base station (uplink) receiver
bandwidths, and also shown in Table 6 and used to derive the downlink row of Table 7 are similar among 5 and
10 MHz UE (downlink) receiver bandwidths.
8
In the NPRM, the Commission recognized that six megahertz of spectrum separation was sufficient to protect
DTV from mobile transmitters. See NPRM, 27 FCC Rcd at 12413-14, paras 156, 158.
9
OET Bulletin No. 69 (Feb. 6, 2004), available at
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet69/oet69.pdf.
10
Calculation distances from the DTV facility to the grid point are set for a 0 dBµV/m F(50,10) contour. This
generally equates to a distance of about 500 km but varies based on terrain and DTV facility parameters.
13

Figure A-3. Illustration of interference prediction from DTV to wireless license area
We note each grid point where the calculated field strength from a co- or adjacent-channel facility
exceeds the appropriate field strength limit. In Figure A-3, predicted interference is shown as blue grid
cells for “TV-47” and green grid cells for “TV-48.” The total market impairment would be based on the
sum of the populations in those unique grid cells where the calculated field strength exceeds the
applicable interference threshold value. If more than one DTV facility causes predicted interference in a
single grid cell, the population associated with that grid cell is only counted once. We apply this
methodology for each co- and adjacent-channel DTV/wireless spectral overlap condition in the range -5
to +5 MHz in every wireless market.
Methodology to Determine Wireless Interference to DTV. Cases 3 and 4 involve interference to a
co- or adjacent-channel DTV receiver from a wireless transmitter operating within the wireless license
area. We divide the area within a DTV station’s noise limited contour into 2 -kilometer cells as specified
in OET Bulletin No. 69, Table 211 and calculate the desired DTV field strength at each grid point. To
calculate the undesired wireless base station transmitter field strength at each cell, we assume a
deployment of hypothetical wireless base stations spaced uniformly every 10 kilometers with transmitting
antennas at 30 meters above ground in every wireless license area within 500 km of the DTV facility. 12

11 “Longley Rice Methodology for Evaluating TV Coverage and Interference,” OET Bulletin No. 69, February 6,
2004 http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet69/oet69.pdf
12 The 3GPP LTE standard supports a maximum cell radius of 100 kilometers. In practice, however, cell radii vary
from fraction of a kilometer in dense urban environments to tens of kilometers in sparsely populated rural areas.
See Commerce Spectrum Management Advisory Committee (CSMAC), Final Report, Working Group 1 – 1695-
1710 MHz Meteorological-Satellite, Rev. 1, July 23, 2013, Appendix 3. The uniform10-kilometer spacing for
base station transmitting sites we describe in this appendix approaches a practical limit on computation.
14

The undesired field strength from each hypothetical base station is then predicted at each grid point within
the DTV noise limited contour and a D/U ratio is determined. The predicted D/U ratio for each grid
point/base station pair is then compared with the appropriate D/U ratio limit to determine whether
interference is predicted to the DTV station.
Figure A-4 illustrates how the spectral overlaps and D/U interference limits would be used to
predict whether a wireless base station transmitter would cause interference to a DTV receiver. In the
example, two DTV stations are assigned channels within the spectrum allocated for wireless use
nationally. Each grid point where the predicted D/U ratio exceeds the appropriate limit is noted along
with the corresponding hypothetical base station location causing the predicted interference. In Figure A-
4, this is illustrated with green grid cells inside the “TV-48” contour and the corresponding hypothetical
interfering base station locations are highlighted inside the wireless license boundary. In this example,
hypothetical base stations transmitting on the D Block (having an overlap of -4 MHz) do not cause
predicted interference within the TV-47 contour, while some base stations (having an overlap of +2 MHz)
do cause interference within the TV-48 contour.
Figure A-4. Illustration of interference prediction from wireless to DTV
This approach would define areas within wireless markets where base station operation may
cause interference to a co- or adjacent-channel DTV facility. To further generalize the areas where
wireless operations could cause interference to a DTV station, we define “restricted” areas based on a
market sub-area (e.g. county boundaries) which lies within the wireless license boundary. In Figure A-5,
counties within the wireless market are identified because at least one hypothetical base station(s) within
a county is predicted to cause co- or adjacent-channel interference to at least one cell on a 2-kilometer
grid in the service area of a DTV station.
15

Figure A-5. Interference from wireless to DTV illustrating restricted operating areas
In the case of wireless uplink to DTV interference (Case 4), the necessary separation distances are
likely to be much smaller than for Cases 1–3. A uniform separation distance of 5 kilometers13 has been
suggested between a co-channel user equipment and a DTV receiver (i.e., no UE transmissions would be
permitted within 5 km of the co-channel DTV station’s contour).

Propagation Model

Prediction of Interfering Field Strength. For Cases 1–3, we use a version of the Longley-Rice
propagation model to make deterministic predictions of desired field strength at receive points. The
presence or absence of interference in each grid cell of the area subject to calculation is determined by
further application of Longley-Rice methodology, taking into account clutter losses, as described below.
Radio paths between undesired transmitters and each 2-kilometer grid point inside the service area are
examined using the Longley-Rice model. At each point, we use the result obtained for median situations
(that is, confidence set to 50%), for 50% of locations, 10% of the time for the prediction of potential
interference to TV receivers from wireless base stations (i.e., F(50, 10)). For prediction of potential
interference from DTV to wireless receivers, we use the result obtained for median situations, for 50% of
locations, 50% of the time (i.e., F(50, 50)).
Methodology to Define DTV Service Area. For digital television, the service area of a station us
defined in the FCC rules; the rules also specify standards for determining interference to DTV service.14

13 See National Association of Broadcasters (NAB) Ex Parte comments file under Proceeding GN 12-268 and
received on 10 July 2013.
14 See 47 CFR § 73.682(d) and § 73.8000. See also OET Bulletin No. 69, Table 5A.
16

Because wireless services are expected to be noise-like and studies have shown that noise-like signals
have interference potential nearly identical to DTV,15 the existing DTV protection criteria can generally
be applied with some adjustments as discussed below.
Under the FCC’s rules, a TV station’s service area is limited to the areas within specific field
strength contours where the station’s field strength exceeds a threshold value. As of the date of this
Public Notice, Class A TV stations can be either analog or digital, but all analog Class A facilities are
required to cease operation by September 1, 2015.16 Full-power TV stations can transmit only in digital
(ATSC).17 There may be analog television facilities operating outside the U.S. to consider in regions
along common borders, however, subject to international negotiations and agreements.18 Prediction of
interference to or from analog television facilities is beyond the scope of this document.
For digital Class A TV stations, service evaluations are made inside the protected contours
defined in 47 CFR § 73.6010, with the exception that the defining field strength for UHF channels is
modified by subtracting a frequency-dependent factor. Thus, the area subject to calculation for digital
Class A TV stations includes the geographic locations at which the field strength is predicted by the FCC
F-curves to exceed the values given in Table 1 at 50% of locations 90% of the time.
Defining Field Strength, dBµV/m, calculated using
Channels
F(50, 90) curves
2 - 6
43
7 - 13
48
14 - 51
51 - 20log10[615/(channel mid-frequency in MHz)]
Table 1. Field Strengths defining the area subject to calculation for digital Class A TV stations
For full-power DTV stations, service is evaluated inside contours determined by the DTV
planning factors in combination with the FCC field strength curves derived for 50% of locations and 90%
of the time. The F(50, 90) curves are calculated for both digital Class A TV stations and for full-power
DTV stations by the formula F(50, 90) = F(50, 50) - [F(50, 10) - F(50, 50)], using the F(50, 50) and F(50,
10) curves in 47 CFR § 73.699.
The defining field strengths for DTV noise-limited service are shown in Table 2. These values,
which are set forth in the rules, are used to determine the area subject to calculation using FCC curves,
and subsequently to determine whether service is present at particular points within this area using
Longley-Rice terrain-dependent propagation model.19

15
See Stephen R. Martin, “Interference Rejection Thresholds of Consumer Digital Television Receivers Available
in 2005 and 2006,” FCC/OET Report TR-07-1003, March 30, 2007. See also “Tests of ATSC 8-VSB Reception
Performance of Consumer Digital Television Receivers Available in 2005,” FCC/OET Report TR-05-1017,
November 2, 2005.
16
See http://www.fcc.gov/guides/dtv-transition-and-lptv-class-translator-stations
17
The transition for full-power stations from analog to DTV was completed in 2009.
18
See http://www.fcc.gov/encyclopedia/international-agreements
19
See 47 CFR § 73.622(e).
17

Defining Field Strength, dBµV/m, calculated using
Channels
F(50, 90) curves
2 - 6
28
7 - 13
36
14 - 51
41 - 20log10[615/(channel mid-frequency in MHz)]
Table 2. Field Strengths defining the area subject to calculation for Digital Full-Power TV stations
Parameter values in Longley-Rice as implemented by the FCC are given in Table 3. In addition
to these parameters, determination of the field strength requires a specification of the percent of time and
locations at which the predicted fields will be realized or exceeded, and generally also a third percentage
identifying the degree of confidence (situational variability) desired in the results. For the purposes of
this methodology, in those cases where error code 3 occurs (KWX = 3), the predicted field strength is to
be accepted as the field strength available at that location.
Parameter
Value
Meaning/Comment
EPS
15.0
Relative permittivity of ground.
SGM (S/m)
0.005
Ground conductivity.
ZSYS
0.0
Coordinated with setting of EN0. See page 72 of NTIA Report.
EN0 (ppm)
301.0
Surface refractivity in N-units.
IPOL
0
Denotes horizontal polarization.
MDVAR
3
Calculation Mode (Broadcast).
KLIM
5
Climate Code (Continental Temperate).
XI (km)
0.1
Terrain sampling interval.
HG(1) (m)
See note
Height of the radiation center above ground.
HG(2) (m)
10
Height of TV receiving antenna above ground.
Note 1. HG(1) in Table 3 is the height of the transmitting antenna radiation center above
ground. For TV, it is determined by subtracting the ground elevation above mean sea
level (AMSL) at the transmitter location from the height of the radiation center AMSL.
The latter value is contained in the FCC's CDBS, and may be found by query at
http://www.fcc.gov/mb/video/tvq.html. The former is retrieved from the terrain elevation
database as a function of the transmitter site coordinates also found in CDBS. Bilinear
interpolation between the surrounding data points in the terrain database is used to
determine the ground elevation. Care should be used to ensure that consistent horizontal
and vertical datums are employed among all data sets.
Table 3. Longley-Rice parameter values
18

Technical Specifications

Field Strength Limits for DTV Interference to Wireless. We define the field strength interference
limit for interference from DTV sources as shown in Table 4.
Spectral Overlap (MHz)
5
4
3
2
1
0
-1
-2
-3
-4
-5
DTV Field Strength
into Wireless Uplink
17.3 18.2 19.5 21.2 24.0 34.4 61.4 62.5 63.7 65.5 68.6
(dBµV/m)
DTV Field Strength
into Wireless Downlink
33.8 34.7 36.0 37.6 40.4 50.7 65.8 66.6 67.6 68.9 70.8
(dBµV/m)
Table 4. Interference field strength values for DTV into wireless
The values shown in Table 4 are derived from the technical specifications and assumptions given in Table
5, Table 6, and Table 7 using the formula below.
Field Strength Limit (dBµV/m) = Pr - Kd - G + L + OTR + OFR(Δf)
Where:
Pr (dBm)
= victim receiver sensitivity level
Kd (dBm-dBµV/m)
= dipole factor at 615 MHz20
G (dBd)
= antenna gain
L (dB)
= line loss
OTR (dB)
= receiver on-tune rejection (dB)
OFR(Δf) (dB)
= off-frequency rejection (dB) as a function of frequency separation

20 See OET Bulletin No. 69, Table 3. The adjustment, Ka = 20 log[615/(channel mid-frequency in MHz)], is added
to Kd to account for the fact that field strength requirements are greater for UHF channels above the geometric
mean frequency of the UHF band and smaller for UHF channels below that frequency. The geometric mean
frequency, 615 MHz, is approximately the mid-frequency of channel 38.
19

Parameter
Value
Comment
Pr (dBm)
-101.5
Reference sensitivity level, per 3GPP Technical Specification
36.104 § 7.2.
Kd (dBm-dBµV/m)
-130.8
Dipole Factor, OET Bulletin No. 69, Table 3.
G (dBd)
13.8
G (dBd) = 12.8 dBd + Gdiv - Ghoriz. Gdiv is receive antenna
diversity gain, assumed to be 3 dB, and Ghoriz is additional
antenna discrimination due to downtilt below the radio horizon,
assumed to be 2 dB.
L (dB)
1
Assumed line loss.
Receiver BW (MHz)
5
For bandwidths (BWs) ≥ 5 MHz, the reference sensitivity level
is measured in accord with the 3GPP Technical Specification
36.104 using 25 consecutive resource blocks, corresponding to a
channel bandwidth of 4.5 MHz.
Thermal noise, Nt
-107.5
= -174 (dBm/Hz) + 10log10(4.5 MHz).
(dBm)
Effective noise figure,
6
Ne (dB)
OTR (dB)
0.8
For TV into wireless, OTR = 10log10(6/5) = 0.8 dB. Using
typical 3 dB transmit signal bandwidths, 10log10(5.38/4.5) is also
approximately 0.8 dB.
OFR(Δf) (dB)
See note
HG(2) (m)
30
Assumed receive antenna height for wireless base stations.
Note: The values for OFR(Δf) were derived using NTIA’s MSAM FDR computer program using
FCC’s emission limits, and DTV and LTE receiver performance standards published by ATSC and
3GPP, respectively. The results are provided in Table 7.
Table 5. Wireless base station receiver technical parameters
Parameter
Value
Comment
Pr (dBm)
-100
Receiver sensitivity level, per 3GPP Technical Specification
36.101 § 7.3.
Kd (dBm-dBµV/m)
-130.8
Dipole Factor, OET Bulletin No. 69, Table 3.
G (dBd)
-2.2
Assumes 0 dBi - 2.2 (approximate dipole gain).
L (dB)
0
Assumed line loss.
Receiver BW (MHz)
5
For bandwidths (BWs) ≥ 5 MHz, the reference sensitivity level
is measured in accord with the 3GPP Technical Specification
36.104 using 25 consecutive resource blocks, corresponding to
a channel bandwidth of 4.5 MHz.
Thermal noise, Nt
-107.5
= -174 (dBm/Hz) + 10log10(4.5 MHz).
(dBm)
Effective noise figure, 7.5
Ne (dB)
OTR (dB)
0.8
For TV into wireless, OTR = 10log10(6/5) = 0.8 dB. Using
typical 3 dB transmit signal bandwidths, 10log10(5.38/4.5) is
also approximately 0.8 dB.
OFR(Δf) (dB)
varies
See Note from Table 5.
HG(2) (m)
1.5
Assume 1.5 m height for user equipment receiver.
Table 6. Wireless user equipment receiver technical parameters
20

Overlap in MHz
5
4
3
2
1
0
-1
-2
-3
-4
-5
OFR (dB)
DTV into Uplink
0
0.9 2.2 3.9 6.7 17.1 44.1 45.2 46.4 48.2 51.3
DTV into Downlink
0
0.9 2.2 3.8 6.6 16.9
32
32.8 33.8 35.1
37
Table 7. Calculated off-frequency rejection (OFR) values for DTV into wireless
D/U Ratio Limits for Interference to DTV. Criteria for thresholds of interference using the ratio
of desired to undesired (D/U) field strengths for TV are specified in 47 C.F.R. § 73.623. The specified
15.2 dB D/U ratio for co-channel interference to DTV service is valid only at locations where the signal-
to-noise ratio is 28 dB or greater. Near the edge of the noise-limited service area, where the predicted
signal-to-noise (S/N) ratio is 16 dB or less, the co-channel D/U ratio is 23 dB. At locations where the S/N
ratio is greater than 16 dB but less than 28 dB, D/U values for co-channel interference to DTV are as
follows:
To protect DTV reception from wireless co-channel interference, the minimum D/U ratios are
computed from the following formula:
D/U = 15 + 10log10[1.0/(1.0-10-x/10)], where x = S/N - 15.19 dB.
The quantity x is the amount by which the actual desired S/N exceeds the minimum required for DTV
reception.
To protect DTV reception from wireless downlink interference for various amounts of spectral
overlap, the minimum D/U ratios are shown in Table 8. These were derived by letting the receive filter
selectivity factor α = 10log10[1.0/(1.0 - 10-x/10)] and applying the OFR(Δf) values for the “Downlink into
DTV” and “Uplink to DTV” cases from Table 9. OTR is set to zero in this case because the DTV
receiver bandwidth is assumed to be larger than the wireless emission.
Spectral Overlap (MHz)
5
4
3
2
1
0
-1 to -521
Downlink to DTV
15.0 + α
14.1 + α
12.8 + α
11.1 + α
8.3 + α
-2.0 + α
-18 + α
D/U Required (dB)
Uplink to DTV
15.0 + α
14.1 + α
12.8 + α
11.2 + α
8.4 + α
-1.9 + α
-16 + α
D/U Required (dB)
Table 8. Threshold Interfering D/U Ratio for Wireless Base Station into DTV

21 We assume -33 dB adjacent channel rejection for the DTV receiver and 43 + 10 log(P) in a 100 kHz bandwidth
attenuation for the wireless emission mask. These flat response curves lead to a constant OFR rejection at
spectral overlaps less than 0 MHz.
21

Overlap in 5
4
3
2
1
0
-1
-2
-3
-4
-5
MHz
OFR
(dB)
Downlink into 0 0.9 2.2 3.9 6.7 17.0 33 33 33 33 33
DTV
Uplink
0 0.9 2.2 3.8 6.6 16.9 31 31 31 31 31
into DTV
Table 9. Calculated off-frequency rejection (OFR) values for Wireless into DTV
In the case of wireless downlink interference to DTV, we recognize that transmitters in multiple
adjacent wireless spectrum blocks have the potential to cause interference to a DTV facility. To offset
this we assume base station ERP based on the power in a 6 MHz channel (see Table 10 and footnote 22).
In the absence of specific information about a wireless base station deployment, hypothetical
wireless base stations are placed uniformly across the wireless license area, spaced approximately 10
kilometers apart. Predicted interference to DTV receivers from those hypothetical base stations is
evaluated to determine whether an area, which could be an entire wireless license area, a county, or a
smaller area such as a 100 square kilometer rectangle corresponding to the spacing of these hypothetical
base stations, may cause interference to any DTV station. That area would then be assumed to be
restricted from wireless base station (downlink) operation, resulting in a market impairment for purposes
of the incentive auction. In the absence of specific information, the ERP and antenna height values given
in Table 10 are used. For wireless user equipment, the ERP and antenna height values given in Table 11
are used. The wireless base station antennas are assumed to be non-directional in the azimuth direction.
Parameter
Value
Comment
Emission BW
5
(MHz)
ERP (W)
72022
Assumes 1.2 kW in 10 MHz channel with two 40 W power amplifiers.
ERP (dBm)
58.6
= 10log10(ERP) + 30.
G (dBd)
12.8
Assumes 15 dBi - 2.2 (approximate dipole gain).
L (dB)
1
Line loss
HG(1) (m)
30
Antenna height above ground
Table 10. Assumed wireless base station transmitting specifications

22 ERP of 720 W = 120 W/MHz x 6 MHz. This adds an additional 0.8 dB of interference power in the wireless
block to simulate operations of wireless base stations transmitting across contiguous adjacent wireless blocks
affecting one 6 MHz TV channel.
22

Parameter
Value
Comment
Emission BW (MHz) 5
ERP (W)
0.12 EIRP = 200 mW – 0 dB Line Loss + 0 dBi Antenna Gain
3GPP TS 36.101, § 6.3.2.
ERP (dBm)
20.8
= 10log10(EIRP) - 2.2 dB.
Gr (dBd)
-2.2
Assumes 0 dBi - 2.2 (approximate dipole gain).
Lr (dB)
0
Line loss
HG(1) (m)
1.5
Antenna height above ground
Table 11. Assumed wireless user equipment transmitting specifications
The interference analysis for TV receivers examines only those cells across the global 2-
kilometer grid that have already been determined to have a desired field above the field strength threshold
for reception given in Table 1 or Table 2, as appropriate. A cell on the global 2-kilometer grid is counted
as receiving interference to TV if the ratio of the desired field to that of any one of the possible undesired
wireless interference sources is less than a certain critical minimum value. The comparison is made after
applying the discrimination effect of the receiving TV antenna and clutter losses, as appropriate.
TV Receiving Antenna Pattern. The TV receiving antenna is assumed to have a directional gain
pattern which tends to discriminate against off-axis undesired stations. This pattern is a planning factor
affecting interference. The specific form of this pattern was chosen by a working group of the FCC
Advisory Committee for Advanced Television Service. The discrimination, in relative field, provided by
the assumed TV receiving pattern is a function of the angle between the lines joining the desired and
undesired stations to the reception point. One of these lines goes directly to the desired station, the other
goes to the undesired station. The discrimination is calculated as the fourth power of the cosine of the
angle between these lines but never exceeds the front-to-back ratio of 14 dB for UHF. When both desired
and undesired stations are on the receive antenna’s boresight, the angle is 0.0 giving a cosine of unity so
that there is no discrimination. When the undesired station is somewhat off-axis, the cosine will be less
than unity and the resulting interference field strength is reduced accordingly; when the undesired station
is far off axis,23 the maximum discrimination given by the front-to-back ratio is attained.

Engineering Databases

DTV Engineering Data. Engineering data for TV stations in the U.S. (including full-power DTV
and Class A) is available from the FCC. Data for individual stations can be found at
http://www.fcc.gov/mb/video/tvq.html, and consolidated data for all authorized stations can be found at
ftp://ftp.fcc.gov/pub/Bureaus/MB/Databases/cdbs/. Where more than one authorization exists for a
particular station, the record associated with the facility actually operating is used. Where specific
elevation pattern data are not provided, a generic elevation pattern may be used as described generally in
OET Bulletin No. 69. The generic elevation pattern should, however, be offset by the amount of
electrical beam tilt specified in the CDBS.

23 Approximately 41.5° at Low VHF, 45° at High VHF, and 48.1° and UHF.
23

Clutter Database and Losses. Land use and land cover (e.g., vegetation and buildings) in the vicinity of
the receiving location can be incorporated through use of a lookup table of clutter losses additional to
those inherent in the basic Longley-Rice v1.2.2 model. The 2006 National Land Clutter Database
(NLCD) is available from the Multi-Resolution Land Characteristics Consortium (MRLC).24 The clutter
loss, if any, at an individual reception location is determined by reference to the NLCD database. The
geographic coordinates of the reception point are compared with the NLCD data to find the point’s NLCD
classification and, subsequently, to determine a clutter loss value from either Table 14 or Table 15, if
applicable, depending on the interference cases listed in Table 12. The clutter loss is subtracted from the
predicted interfering signal strength.
Receive Antenna Height
Interference Case
Transmitter Antenna Height (m)
Apply Clutter?
(m, AGL)
Case 1: TV into
Value from CDBS (AMSL)
30
No
Uplink:
Case 2: TV into
Yes
Value from CDBS (AMSL)
1.5
Downlink:
(Table 15)
Yes, only for
Case 3: Downlink
30 (AGL)
10
undesired path
into TV:
(Table 14)
Yes, only for
Case 4: Uplink into
1.5 (AGL)
10
undesired path
TV:
(Table 15)
Table 12. Applicability of Clutter Losses to Interference Case
NLCD Categories. Since the NLCD classifications have a broader purpose and are not targeted
for application to radio propagation analyses, we have regrouped these classifications into more
appropriate categories for use in this methodology. Table 13 defines this regrouping. For each computer
run of the program, the appropriate clutter category number should be selected from Table 13 according
to environmental conditions in the vicinity of the individual reception point. The clutter loss value, if
any, is then determined as a function of the clutter category number and the TV channel number, by
referring to either Table 14 or Table 15, if applicable depending on the interference cases listed in Table
12.

24 See http://www.mrlc.gov/nlcd2006.php
24

NLCD
TVStudy Clutter
Classification
Category
TVStudy Clutter
Number
NLCD Classification Description25
Mapping
Category Description
11
Water
4
Water
12
Perennial Ice Snow
10
Snow and Ice
21
Developed, Open Space
7
Residential
22
Developed, low intensity
7
Residential
23
Developed, Medium Intensity
9
Commercial / Industrial
24
Developed High Intensity
8
Mixed urban / buildings
31
Bare Rock / Sand / Clay
1
Open Land
41
Deciduous Forest
5
Forest Land
42
Evergreen Forest
5
Forest Land
43
Mixed Forest
5
Forest Land
52
Shrub/Scrub
3
Rangeland
71
Grasslands/Herbaceous
3
Rangeland
81
Pasture/Hay
2
Agricultural
82
Row Crops
2
Agricultural
90
Woody Wetlands
5
Forest land
95
Emergent Herbaceous Wetlands
6
Wetland
Table 13. Regrouping of NLCD Categories for Longley Rice Applications
Clutter Loss (dB)26
(to be subtracted from calculated field strength)
Clutter
Clutter
Channels
Channels
Channels
Channels
Category
Category Description
2-6
7-13
14-36
38-51
1
Open land
0
0
4
5
2
Agricultural
0
0
5
6
3
Rangeland
0
0
3
6
4
Water
0
0
0
0
5
Forest land
0
0
5
8
6
Wetland
0
0
0
0
7
Residential
0
0
5
7
8
Mixed Urban / Buildings
0
0
6
6
9
Commercial / Industrial
0
0
5
6
10
Snow and Ice
0
0
0
0
Table 14. Clutter Loss as a Function of NLCD Clutter Category and TV Channel for Interference Cases
Involving the Wireless Base Station to DTV

25 The NLCD2006 classification descriptions can be found at http://www.mrlc.gov/nlcd06_leg.php
26 See OET Bulletin No. 73 (Nov. 23, 2010), available at
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet73/oet73.pdf
25

Clutter Loss (dB)27
(to be subtracted from calculated field strength)
Clutter
Clutter
Channels
Channels
Channels
Channels
Category
Category Description
2-6
7-13
14-36
38-51
1
Open land
0
0
6
7
2
Agricultural
0
0
5
6
3
Rangeland
0
0
3
6
4
Water
0
0
0
0
5
Forest land
0
0
10
13
6
Wetland
0
0
0
0
7
Residential
0
0
11
13
8
Mixed Urban / Buildings
0
0
13
13
9
Commercial / Industrial
0
0
12
13
10
Snow and Ice
0
0
0
0
Table 15. Clutter Loss as a Function of NLCD Clutter Category and TV Channel for Interference Cases
Involving the Wireless User equipment

27 For cases involving wireless user equipment (Cases 2 and 4), in which half of the link is presumed to be at a
height below the clutter, we adjusted clutter losses to account for the presumed 1.5 meter user equipment height.
We used the nominal clutter category heights provided in ITU Recommendation P.452 (http://www.itu.int/rec/R-
REC-P.452/en), along with the equations included in that recommendation, to develop adjustment factors for
each clutter category, and reduced the clutter values on the record in OET Bulletin No. 73 by our derived
adjustment factors.
26

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