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NTIA Report 05-432INTERFERENCE PROTECTION CRITERIAPhase 1 - Compilation from Existing Sourcestechnical reportU.S. DEPARTMENT OF COMMERCE National Telecommunications and Information Administration

NTIA Report 05-432INTERFERENCE PROTECTION CRITERIAPhase 1 - Compilation from Existing SourcesAlakananda PaulGerald HurtThomas SullivanGary PatrickRobert SoleLarry BrunsonCou-Way WangBernard JoinerEdward DrocellaContributorsSuzette WilliamsGentiana SaamU.S. Department of CommerceCarlos M. Guiterrez, SecretaryMichael D. Gallagher, Assistant Secretaryfor Communications and InformationOctober 2005

EXECUTIVE SUMMARYThe National Telecommunications and Information Administration (NTIA)launched this two-phase study of interference protection criteria (IPC) in order tocompile, explain and validate, modify or supplement the levels of protection frominterference that are generally expected and provided for various radiocommunicationsystems. The study is an integral part of President Bush’s Spectrum Policy Initiativethat was established in May 2003 to promote the development and implementation of aUnited States spectrum policy for the 21st century. The Secretary of Commerce thenestablished a Federal Government Spectrum Task Force and initiated a series of publicmeetings to address improvements in policies affecting spectrum use by the FederalGovernment, State, and local governments, and the private sector. Therecommendations resulting from these activities were included in a two-part series ofreports released by the Secretary of Commerce in June 2004, under the title SpectrumPolicy for the 21st Century - The Presidents Spectrum Policy Initiative. Based on therecommendations contained in these Reports, the President directed the federalagencies on November 30, 2004, to plan the implementation of the 24recommendations contained in the Reports. There were several recommendations thatwill consider the interference protection criteria contained in this study including: assessment of new technologies and their impact on incumbentradiocommunications;managing interference;development of a “Best Practices Handbook” for spectrum engineering;establishment a pilot program and long-range plan for improved sharing ofspectrum between federal and non-federal entities; andcreation of new analytical computer models that will facilitate spectrumengineering.The U.S. spectrum management process has evolved to meet the rapidlychanging spectrum requirements of both the private sector and the federal government.Within this spectrum management process, the Federal Communications Commission(FCC), acting on behalf of the private sector, and the NTIA, acting on behalf of thefederal agencies, provide spectrum planning, allocation and assignment in a mannerthat prevents interference. In the last five to ten years, spectrum usage and demandhave increased significantly. Associated with the increased spectrum usage demand,came the increased geographic densities of transmitters and receivers, that meansincreased interference risks. One of the key elements in preventing interference isidentification of the appropriate IPC. Implementation of a new technology often requiresa significant amount of time to define and obtain agreement on an appropriate IPC. Forexample, it took several years to obtain sufficient measurement and analyticalinformation on potential interference from ultrawideband (UWB) devices in order todefine and apply the necessary IPC. To speed up the introduction of a new technologyassociated with the addition of licensed or unlicensed operations, means thatadvocates, incumbents and regulators will have to find more effective ways for

analyzing the potential interference in a more timely manner. To this end, it isappropriate to predict and define the interfering signal levels at which radio systemsmay experience unacceptable degradation in performance, and to establish methods forprotection of radio communications from interference.One of the key steps in any interference, electromagnetic compatibility, orspectrum sharing study is identifying IPC, to determine the necessary distance orfrequency separations, or other frequency sharing constraints. The identification of IPCis often a confusing, time-consuming step with no single reference source from which todraw. The complexity of this process is exacerbated by the numerous terms used todefine interference. For example, the NTIA, FCC, and International TelecommunicationUnion, Radiocommunication Sector or (ITU-R), define various terms relative tointerference, including: Interference, Permissible Interference, Accepted Interference,and Harmful Interference. The diverse concepts behind these terms can lead toconfusion when addressing potential interference between systems. Furthermore, sinceIPC normally depend upon details of the interfering and interfered-with systems as wellas their operating environments, a very large number of combinations of frequencysharing situations must be considered with regard to a proposed new service ortechnology.NTIA reviewed publications of national, international, public and privateorganizations to compile established IPC for various radio services operating between30 MHz and 30 GHz. The results are presented in this Phase 1 report. One commonfeature was that for continuous, long-term interfering signal levels, nearly all establishedIPC were based on an interference-to-noise power ratio of –6 to –10 dB. Short-termIPC that accommodate relatively high interfering signal levels for small percentages oftime or locations were not found for many services. For pulsed or intermittent interferingsignals, the IPC for many of the radio services were not specified or the available IPCvaried due to the specific types of desired and interfering signals being received.In the second phase of this study, NTIA will review the relevant federalgovernment policies and practices regarding IPC and recommend regulatory andtechnical refinements that may improve IPC application’s scope, utility, clarity, oreffectiveness.ii

ACRONYMS AND VCCIRCDACDCDMACEPTCFRC/IC/(I N)C/NCWDAQdBdBidBicdBmdBμDBSdBWdBZAerospace and Flight Test Radio Coordinating CouncilArticulation IndexAeronautical Mobile-Satellite ServiceAeronautical Mobile-Satellite Service (Off-route)Aeronautical Mobile-Satellite Service (Route)American National Standards InstituteAppendix 30 of the ITU Radio RegulationsAssociation of Public-Safety Communications OfficialsAutomatic Picture TransmissionAeronautical Radio IncorporatedAir Traffic Control Radar Beacon SystemAir Traffic ManagementAutomatic Transmitter Power ControlAdvanced Television Systems CommitteeBackground Block Error RatioBit Error ProbabilityBit Error RatioBroadcasting ServiceBroadcasting-Satellite ServiceBandwidthCoarse AcquisitionCommunity Antenna TelevisionInternational Radio Consultative Committee (now called“ITU-R”)Command and Data Acquisition SystemColor DecodingCode Division Multiple AccessEuropean Conference of Postal and TelecommunicationsAdministrationsCode of Federal RegulationsCarrier-to-Interfering Signal Power RatioCarrier-to-Interference-plus-Noise Power RatioCarrier-to-Noise Power RatioContinuous WaveDelivered Audio QualityDecibelAntenna gain in dB over isotropicAntenna gain in dB over isotropic (circular polarized)Power in dB referred to 1 milliwattField strengths in dB above one microvolt per meterDirect Broadcast SatellitePower in dB referred to 1 wattRadar reflectivity factor in dBiii

ISDB-TDistance Measuring EquipmentDigital Microwave SystemDraft New RecommendationDepartment of DefenseData Relay SatelliteDigital TelevisionDesired-To-Undesired Signal Power RatioDigital Video Broadcasting-TerrestrialElectronic Communications CommitteeEarth Exploration-SatelliteElectronics Industry AllianceElectromagnetic CompatibilityEuropean Radiocommunications OrganizationErrored Second RatioEuropean Telecommunications Standards InstituteExtra-Vehicular ActivityFederal Aviation AdministrationFederal Communications CommissionFrequency Division Multiple AccessFractional Degradation of PerformanceForward Error CorrectionFrequency HoppingFrequency ModulationFixed ServiceFixed-Satellite ServiceGigahertz (109 Hertz)Global Navigation Satellite System (Russian)Global Navigation Satellite SystemGlobal Positioning SystemGlobal Recorded DataGeostationary Satellite OrbitHigh Definition TelevisionHypothetical Reference Digital PathHigh Resolution Picture TransmissionHertzIn-band on-channelInternational Civil Aviation OrganizationInternational Electrotechnical CommissionInstitute of Electrical and Electronics EngineersInstrument Landing SystemInternational Maritime OrganizationInternational Mobile Telecommunications-2000Interfering-to-Noise Power RatioInternet ProtocolInterference Protection CriteriaIntegrated Service Digital Broadcasting-Terrestrialiv

RNSSIntegrated Services Digital NetworkIndustrial, Scientific, and MedicalInternational Telecommunication UnionITU Radiocommunication SectorITU Telecommunications Standardization SectorJoint Spectrum CenterJoint Task ForceKelvinKilobits per secondKilohertz (103 Hertz)Land Mobile-Satellite ServiceLow Earth OrbitLow Resolution Picture TransmissionMeterMegabits per secondMultiple Exposure AllowanceMeteorological-SatelliteMegahertz (106 Hertz)Military StandardMicrowave Landing SystemMaritime Mobile-Satellite ServiceMobile ServiceMobile-Satellite ServiceMulti-Channel Video Distribution and Data ServiceNoise-to-Carrier RatioNon-Geostationary Satellite OrbitNon-Interference-BasisNotice of Proposed RulemakingNot SpecifiedNational Telecommunications and InformationAdministrationNational Television Standards CommitteeNational Weather ServiceNumerical Weather PredictionOffice of Spectrum ManagementOne-Stop-Shopping ProcedurePulse Code ModulationPower Flux DensityPrivate Land Mobile RadioQuadrature Phase Shift KeyingUnited Kingdom Radiocommunications AgencyRadio Astronomy ServiceRecommendationRadio FrequencyRoot Mean SquareRadionavigation-Satellite Servicev

o RegulationsRadio Technical Commission on AeronauticsRadio Technical Commission on MaritimeSynthetic Aperture RadarsSingle Channel Per CarrierSeverely Errored Second RatioStudy GroupSignal-to-Interference Power RatioSignal to Interference, Noise, and Distortion Power RatioSpectrum Policy Task ForceTactical Air NavigationTo Be DeterminedTime Division Multiple AccessTelecommunications Industry AssociationTelecommunications Systems BulletinUltra High Frequency – 300 to 3000 MHzUnited States Coast GuardUltrawidebandVery High Frequency – 30 to 300 MHzVery Long Baseline InterferometryVery-High-Frequency Omnidirectional RangeVery Small Aperture TerminalWide Area Augmentation SystemWeather FacsimileWorld Meteorological OrganizationITU-R Working Party 8BWorld Radiocommunication Conferencevi


SECTION 5 RADIODETERMINATION AND TION5- SERVICERadars operated in the Radiolocation, Aeronautical Radionavigation,Meteorological Aids, and Maritime Radionavigation ServicesCW and Noise-like Interfering SignalsPulse-Like Interfering SignalsImpulse-Like Interfering SignalsAeronautical Radionavigation Systems (other than radars using SATELLITE SERVICEIPC Values for GPS ION 6 BROADCASTING AND BROADCASTING-SATELLITE TING SERVICEBroadcast TelevisionFM Radio 66.3.7BROADCASTING-SATELLITE SERVICEAppendix 30 (AP30) of the ITU Radio RegulationsRecommendation ITU-R BO.1297Recommendation ITU-R BO.1444FCC Report and Order 00-418Mitre Technical ReportSpectrum XXIFurther SECTION 7 MOBILE AND MOBILE SATELLITE .4MOBILE SERVICEMobile Service in GeneralLand Mobile ServiceMaritime Mobile ServiceAeronautical Mobile Service7-17-17-37-57- SATELLITE SERVICEGeostationary Satellite ServiceNongeostationary Satellite Service - DownlinkNGSO Satellite Service (Cospas-Sarsat Uplink)7-77-77-87-87.4SUMMARY7-8SECTION 8 SCIENCE SERVICES8-1viii

8.1INTRODUCTION8- RESEARCH SERVICEDeep-Space ResearchNear Earth Space ResearchData Relay SatellitesTelecommunication Links in the 37-40 GHz Bands8-18-18-38-48-48.3SPACE OPERATION SERVICE8-58.4METEOROLOGICAL AIDS8-58.5EARTH EXPLORATION-SATELLITE AND METEOROLOGICAL SATELLITESERVICES8-6Space-to-Earth Data Transmission Systems Using Low-Earth Orbit8-6Data Dissemination and Direct Data Readout Systems Using GeostationarySatellites8-7Service Links in Data Collection Systems8-7Command and Data Transmission System8-7Satellite Passive Remote Sensing8-8Spaceborne Active Microwave Remote Sensors8- ASTRONOMY8.7SUMMARY8-98-10ix

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SECTION 1INTRODUCTION1.1BACKGROUNDThe National Telecommunications and Information Administration (NTIA)is the Executive Branch agency responsible for developing and articulatingdomestic and international telecommunications policy. NTIA acts as the principaladvisor to the President on telecommunications policies pertaining to the nation’seconomic and technological advancement and regulation of thetelecommunications industry. NTIA is also responsible for managing the federalgovernment’s use of the radio spectrum. Federal agencies are highly dependenton interference-free spectrum access to support a wide variety of criticalmissions including weather forecasting and homeland security.The spectrum management process, originally established under theCommunications Act of 1934,has been frequently faced with rapidly changingperceived spectrum requirements of both the private sector and the federalgovernment. The Federal Communications Commission (FCC), and NTIA havecoordinated their spectrum management efforts to ensure that policies, rules, andpractices for spectrum usage adequately prevent interference.One of the primary goals in spectrum management is to plan, allocate andassign spectrum in a way that prevents interference. This goal was discussed atNTIA’s April 2002 Spectrum Summit of the federal and private sector spectrummanagement community as well as the radio service users and providers. Inparallel, the FCC created a Spectrum Policy Task Force (SPTF) that focused ona number of issues, including interference, and formed an Interference ProtectionWorking Group (IPWG). This forum posed several relevant questions. Forexample, how does one determine whether interference is harmful? What are theproperty rights of the licensed or assigned user? What are the property rightsrelative to freedom from interference? Many participants indicated that answersneed to be developed with a clear view of the necessary spectrum managementpolicies and conditions under which interference will be prevented.On June 6, 2002, the FCC SPTF issued a public notice seeking commenton issues related to the FCC’s spectrum policies.1 The IPWG held several publicworkshops where the public was invited to present input. Over forty-eightcompanies provided comments on interference protection, suggesting that bothlicensed and unlicensed spectrum users should have clearly defined rights andobligations relating to interference. Participants also suggested that the UnitedStates integrates its domestic and international spectrum policy efforts oninterference and concluded that interference protection was at the heart of manycontentious debates before the FCC and NTIA. Furthermore, commenters1-1

suggested that both agencies should recognize and address several keyinterference principles:2 some level of interference can be tolerated, which varies depending on thenature of the service involved and the nature of the interference;due to advances in digital signal processing and antenna technology,communications systems and devices are becoming more tolerant ofinterfering signals through their ability to sense and adapt to the RFenvironment;all systems require some degree of margin to ensure reliablecommunications; the regulators should not assume that eliminating thatmargin is acceptable;the regulations and practices of interference protection differ betweendifferent radio services, with the rules of some services prescribingdetailed criteria for predicting interference;the regulators should consider interfering signal aggregation of multiplesources;harmful interference is an extreme level and that just because interferencedoes not rise to that level, it cannot be concluded that the interference isacceptable to the victim; andthe FCC should make clear that its spectrum policies are based on an“interference-limited” rather than “ambient noise-limited” environment.The SPTF provided a report of its findings and recommendations to the FCC inNovember 2002.3In the last five to ten years, spectrum usage and demand have increasedsignificantly. The major interference issues have required a substantial time todefine and resolve. For example, in adopting rules for implementing the newtechnology referred to as ultrawideband (UWB), it took several years to obtainmeasurement and analytical information on interference susceptibility, sufficientto define the necessary Interference Protection Criteria (IPC). In order toaccommodate new technologies and additional licensed and/or unlicensedoperations more quickly, advocates, incumbents and regulators will have to findbetter ways to analyze the interference potential. Moreover, system designersneed guidance on the levels of interfering signals that should be tolerated. Tothis end, it is appropriate to further define IPC.The identification of the appropriate IPC is often a confusing, timeconsuming process that is not supported by a single reference source. Thisprocess is further complicated by numerous relevant regulatory and technicalterms. For example, the NTIA, FCC, and the International TelecommunicationUnion, Radiocommunication Sector, (ITU-R) define several terms relative tointerference, including: Interference, Permissible Interference, AcceptedInterference, Harmful Interference, and Protection Ratios. Other terms that arecommonly used, but not specifically defined are: Allowable Performance1-2

Degradation, Interference Protection Criteria, and Spectrum Sharing Criteria.Furthermore, since spectrum-sharing criteria normally depend upon parametersof both the interfering and interfered-with systems and their operatingenvironments, a very large number of combinations is possible. Consideration ofinterference is “at least a six dimensional problem, meaning spatial, x-y-z,frequency, time, and waveform, and of course since the waveform can beinfinitely complicated, you can make it an n-fold problem, which basically hasmore variables than you have numbers.”4In 1990, International Telecommunication Union, Radiocommunicationsector, Study Group 1 attempted to reduce this complexity by adopting Rec. ITUR SM.669 that includes a matrix of protection ratios for various combinations ofinterfering and desired-signal modulation types.5 An earlier, but morecomprehensive approach was undertaken jointly by NTIA and the Department ofDefense (DOD) Joint Spectrum Center (JSC), resulting in the publication of theCommunications Receiver Performance Degradation Handbook.6 However, theIPC presented in Rec. ITU-R SM.669 as well as the Degradation Handbook havebecome largely obsolete for several reasons, including:1)The Degradation Handbook and Rec. ITU-R SM.669 focus on analogand early digital modulations, which are in many cases being supplanted by morecomplex, digital modulations.2) Both efforts focused primarily on modulation with little regard to radioservice requirements or factors stemming from the operating frequency, whereasmost spectrum sharing studies today focus primarily on radio services andspecific frequency bands.3) The IPC in these texts do not include temporal or spatial statisticalallowances that should be considered in detailed analyses.Since the adoption of Rec. ITU-R SM.669 and completion of theDegradation Handbook, extensive spectrum sharing studies have beencompleted and documented within the International Telecommunication Union,Radiocommunication sector, and elsewhere. As part of on-going spectrumsharing studies within the International Telecommunication Union,Radiocommunication sector, the various service study groups have refined anddocumented IPC for their respective radio services within numerous InternationalTelecommunication Union, Radiocommunication sector Recommendations. Inlight of these developments, NTIA launched a study of IPC. This Phase 1 reportcompiles available IPC. In the second phase of this study, NTIA will review therelevant federal government policy and practices regarding derivation of IPC, andrecommend regulatory and technical refinements that may improve IPCapplication’s scope, utility, clarity, or effectiveness.1-3

1.2OBJECTIVEThe National Telecommunications and Information Administration (NTIA)launched a two-phase study of interference protection criteria (IPC) to compile,explain and validate, modify or supplement the levels of protection frominterference that are generally expected and provided for variousradiocommunication systems.The study is an integral part of President Bush’s Spectrum Policy Initiativethat was established in May 2003 to promote the development andimplementation of a United States spectrum policy for the 21st century. TheSecretary of Commerce then established a Federal Government Spectrum TaskForce and initiated a series of public meetings to address improvements inpolicies affecting spectrum use by the Federal Government, State, and localgovernments, and the private sector. The recommendations resulting from theseactivities were included in a two-part series of reports released by the Secretaryof Commerce in June 2004, under the title Spectrum Policy for the 21st Century The Presidents Spectrum Policy Initiative. Based on the recommendationscontained in these Reports, the President directed the federal agencies onNovember 30, 2004, to plan the implementation of the 24 recommendationscontained in the Reports. There were several recommendations that willconsider the interference protection criteria contained in this study including: assessment of new technologies and their impact on incumbentradiocommunications;managing interference;development of a “Best Practices Handbook” for spectrum engineering;establishment a pilot program and long-range plan for improved sharing ofspectrum between federal and non-federal entities; andcreation of new analytical computer models that will facilitate spectrumengineering.Based on the above, the objectives of this study are as follows:Phase 1: Review publicly available texts to identify and document IPC for radioservices that accommodate federal government radiocommunications andapply this information as applicable to the completion of the appropriaterecommendations approved by President Bush.Phase 2: Review federal government policy and practices regarding IPC andrecommend regulatory refinements that may improve the scope, clarity or1-4

effectiveness of interference-protection provisions, as appropriate; Review applications for IPC; Develop a methodology for determining appropriate IPC that can be usedto supplement, validate or refine existing IPC;Additional objectives will be determined during Phase 2 of this study.These may include: Apply the methodology for determining appropriate IPC to supplement orrefine, as appropriate, IPC identified in Phase 1 to establish validated IPCfor each radio service; Incorporate findings in NTIA’s planned best practices handbook; On a case-by-case basis, promote IPC and associated regulatoryprovisions for the private sector through rulemakings at the FCC; Provide the results to ITU-R Study Group 1 for possible replacement ofRec. ITU-R SM.669.1.31.4PHASE 1 APPROACH Define IPC. Compile IPC in five broad areas covering fixed and fixed-satellite services,radiodetermination and radiodetermination-satellite services, broadcastingand broadcasting–satellite services, mobile and mobile-satellite services,and science services. Categorize IPC according to the type of interfering signal (continuouswave (CW), noise-like, pulse, and other) and, where available, associatedstatistical allowances (long-term or short-term). Document results in an NTIA Phase 1 report.SCOPEThis report includes IPC covering the frequency range 30 MHz to 30 GHz.Numerous sources of IPC are available from international agencies, governmentagencies, trade associations, academic institutions, and others. This reportcompiles IPC from generally accepted sources. The sources considered were asfollows:1-5

ITU-R. A role of the ITU-R is to provide guidance for the rational,equitable, efficient, and economical use of the radio-frequency spectrumby all radiocommunication services. The ITU-R carries out studiesculminating in Recommendations, which serve as a repository of technicaland procedural guidelines for the design, implementation and operation ofradiocommunications systems. The ITU-R Study Groups (SG) listedbelow focus on particular radiocommunications services, as do thesubsequent sections of this report. Working parties are established withineach Study Group to address service issues such as performanceobjectives. SG 1 - Spectrum managementSG 3 - Radiowave propagationSG 4 - Fixed-satellite serviceSG 6 - Broadcasting serviceSG 7 - Science servicesSG 8 - Mobile, radiodetermination, amateur and related satelliteservicesSG 9 - Fixed service International Civil Aviation Organization (ICAO). One of the chief activitiesof the ICAO is the establishment of International Standards,Recommended Practices and Procedures covering the technical fields ofaviation including aeronautical telecommunications, air traffic services,search and rescue, navigation, surveillance, and aeronautical informationservices. The principle document considered herein is the ICAOInternational Standards and Recommended Practices. International Maritime Organization (IMO). The IMO was established withthe chief task of developing a comprehensive body of the internationalconventions, codes and recommendations to be implemented by allmember governments. The Maritime Safety Committee has subcommittees dealing with relevant subjects, including safety of navigation,radiocommunications and search and rescue. International Electrotechnical Commission (IEC). The IEC is a globalorganization that prepares and publishes international standards for allelectrical, electronic and related technologies. These serve as a basis fornational standardization and as references when drafting internationaltenders and contracts. World Meteorological Organization (WMO). The WMO coordinates globalscientific activity to allow increasingly prompt and accurate weatherinformation services for public, private and commercial use, includinginternational airline and shipping industries. WMO's major scientific andtechnical programs include the World Weather Watch, which offers up-to-1-6

the-minute world-wide weather information through member-operatedobservation systems and telecommunication links (presently using fourpolar-orbiting and five geostationary satellites, about 10,000 landobservation stations, 7,000 ship stations and 300 moored and driftingbuoys carrying automatic weather stations). European Radiocommunications Organization (ERO). ERO is thepermanent office supporting the Electronic Communications Committee(ECC) of the European Conference of Postal and TelecommunicationsAdministrations (CEPT). ECC is the Committee that brings together theradio and telecommunications regulatory authorities of the 45 CEPTmember countries. National Telecommunications and Information Administration (NTIA).NTIA is the Executive Branch agency principally responsible fordeveloping and articulating domestic and international telecommunicationspolicy as well as managing and regulating federal government use of thespectrum. Accordingly, NTIA conducts studies and makesrecommendations regarding telecommunications matters to Congress, theFCC, and the public. NTIA rules and publications include the NTIAManual and the library of reports produced by the Office of SpectrumManage

ISDN Integrated Services Digital Network ISM Industrial, Scientific, and Medical ITU International Telecommunication Union ITU-R ITU Radiocommunication Sector ITU-T ITU Telecommunications Standardization Sector JSC Joint Spectrum Center JTF Joint Task Force K Kelvin Kbps Kilobits per second kHz Kilohertz (103 Hertz)

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