全球定位系统接收机与邻带基站兼容性评估

Technical Memorandum ASSESSMENT OF COMPATIBILITYBETWEEN GLOBAL POSITIONINGSYSTEM RECEIVERS ANDADJACENT BAND BASE STATIONAND USER EQUIPMENTTRANSMITTERS Edward DrocellaCou-Way WangNickolas LaSorte U.S. Department of Commerce Adam Candeub, Acting Assistant Secretary of Commerce for Communications andInformation December 2020 ACKNOWLEDGEMENTS The National Telecommunications and Information Administration (NTIA) and theauthors would like to thank the members of the Interdepartment Radio Advisory Committee’sTechnical Focus Group (TFG) for their support in completing this assessment of thecompatibility between Global Positioning System (GPS) receivers and adjacent band base stationand user equipment transmitters. GPS is perhaps best known for its utility as a navigation aid inautomobiles and for its use in mobile Internet applications as a location based service offered bycommercial providers. However, GPS is relied upon worldwide in aeronautical, maritime, andground-based navigation; surveying; construction; precision agriculture; timing synchronization(e.g., telecommunications, digital television, power distribution, banking, financial transactions,and the Internet); emergency medical response (e.g., E911) and disaster management; and searchand rescue operations. While this technical memorandum presents NTIA’s technical analyses, the inputsprovided by representatives on the TFG from the United States Air Force GPS Directorate,Department of Energy, Department of Transportation, Federal Aviation Administration, NationalAeronautics and Space Administration, Department of Defense Office of Chief InformationOfficer, and Federal Communications Commission were essential to completing this assessment. The authors would like to thank William Doolan and Jeffery Deveraux, formerly withNTIA’s Office of Spectrum Management Spectrum Engineering and Analysis Division (SEAD)for their contributions to the initial analyses and early drafts of this technical memorandum alongwith Suzette Williams, also from SEAD, for providing technical editing support in preparing thisdocument. The authors also acknowledge and appreciate the technical support provided by PaulMcKenna from NTIA’s Institute for Telecommunication Sciences. EXECUTIVE SUMMARY On December 31, 2015, Ligado Networks submitted applications to the FederalCommunications Commission (FCC) to modify licenses for the ancillary terrestrial component(ATC) of its L-band mobile satellite service (MSS) in order to enable the provision ofcommercial wireless services. The proposed terrestrial operations would use three radiofrequency spectrum band segments: base stations in the 1526-1536 MHz portion of the MSSdownlink band and user equipment in the 1627.5-1637.5 MHz and 1646.5-1656.5 MHz portionsof the MSS uplink band. Ligado has agreed to limit unwanted emissions (spurious emissions andout-of-band emissions) in the 1559-1610 MHz Radionavigation-Satellite Service (RNSS)allocation and to reduce the ATC base station power in the 1526-1536 MHz band.1 On April 22, 2016, the FCC released a public notice seeking comment on, among otherthings, the extent to which Ligado’s modified applications would address Global PositioningSystem (GPS) interference concerns. Soon thereafter, the Chair of the Interdepartment RadioAdvisory Committee (IRAC) established a Technical Focus Group (TFG) to address technicalissues raised in the FCC’s public notice. Engineers from NTIA’s Office of SpectrumManagement, in collaboration with subject matter experts from the United States Air Force GPSDirectorate, Department of Energy, Department of Transportation, Federal AviationAdministration (FAA), the National Aeronautics and Space Administration (NASA), theDepartment of Defense Office of Chief Information Officer, and the FCC, participated in theTFG. This technical memorandum provides the results of the TFG’s compatibility assessmentbetween terrestrial GPS L1 coarse/acquisition (C/A) code receivers operating in the 1559-1610MHz RNSS band and terrestrial operations in the 1526-1536 MHz, 1627.5-1637.5 MHz, and1646.5-1656.5 MHz bands. The TFG assessed compatibility between different categories ofGPS L1 C/A code receivers and the proposed terrestrial deployment by examining thedegradation in carrier-to-noise density ratio (C/N0), loss-of-lock, position error, and increase inacquisition/reacquisition time for GPS receivers.2 This technical memorandum summarizes the results of the TFG’s GPS receiver analysesand terrestrial deployment simulations. The GPS receiver analyses consisted of data synthesis ofthe measurements from the different test programs for tracking and acquisition/reacquisitionmodes, effects of the antenna on measured interference power levels, and position errordistribution measurements. The GPS receiver categories measured included: high precision,general location/navigation, timing, cellular, and general aviation. Based upon the measurementdata from multiple test programs: •It is difficult