评估5350 5470 mhz和5850 5925 mhz频段

U.S. Department of Commerce Rebecca Blank, Acting Secretary Lawrence E. Strickling, Assistant Secretaryfor Communications and Information January 2013 EXECUTIVE SUMMARY Through this report, the National Telecommunications and Information Administration(NTIA) presents the results of its initial study on the potential use of up to 195 megahertz ofspectrum in the 5 gigahertz (GHz) band by Unlicensed-National Information Infrastructure (U-NII) devices. Pursuant to Section 6406(b)(1) of the Middle Class Tax Relief and Job Creation Act of2012 (Tax Relief Act),1NTIA, in consultation with the Department of Defense and otherimpacted agencies, assessed known and proposed spectrum-sharing technologies. This studyalso evaluated the risk to federal users if the Federal Communications Commission (FCC) allowsU-NII devices to operate in the 5350-5470 MHz and 5850-5925 MHz bands.2 Under current FCC regulations, U-NII devices are authorized to use 555 megahertz ofspectrum in the 5150-5350 MHz and the 5470-5825 MHz bands subject to specific technical andoperational restrictions to enable sharing with protected radar and satellite operations. U-NIIdevices provide short-range, high-speed unlicensed wireless connections in the 5 GHz band for,among other applications, Wi-Fi-enabled radio local area networks, cordless telephones, andfixed outdoor broadband transceivers used by wireless internet service providers. Unlicensedwireless broadband systems have become critical complements to licensed commercial mobilenetworks and to fixed wireline networks. For example, smart phones, tablets, net-books andlaptops typically have inexpensive embedded Wi-Fi capabilities that enable high-speedbroadband connectivity in a wide array of locations. International industry standards currently under development will enable the provision ofsignificantly higher data throughput in the 5 GHz bands by using wider radiofrequency (RF)bandwidths, more data streams, and high-density signal modulation techniques. The wider RFbandwidth requirements may require larger blocks of contiguous frequencies and expanding theamount of spectrum authorized for U-NII device operation in the 5 GHz band will increase thecontiguous spectrum that is available. Several federal agencies currently use the two potential 5 GHz expansion bands that arethe subject of this study. Federal systems in these bands include a variety of radar systemsinstalled on airborne, ground-based, shipborne, and space-based platforms. In addition to radaroperations, federal users operate a number of airborne RF communications systems at sitesacross the United States in these bands to conduct, for example, testing and training of unmanned aircraft systems (UAS) data and command links for intelligence, surveillance, reconnaissanceand combat search and rescue missions. The Department of Homeland Security also operatesUAS in the 5350-5470 MHz band for drug interdiction and border surveillance operations. Inthe 5850-5925 MHz band, additional allocated and authorized uses include non-federal fixed-satellite uplinks (Earth-to-space) and federal and non-federal mobile services. The non-federalmobile service allocation is limited to Dedicated Short Range Communications Service(DSRCS) systems operating in the Intelligent Transportation System radio service. For this study, NTIA assumed that the federal agencies will not alter their systems oroperations to accommodate U-NII devices on a shared basis in the potential 5 GHz expansionbands. NTIA also based its analysis on an assumption that the FCC’s existing requirements forsituation-aware spectrum-sharing technologies that apply in some of the existing 5 GHz bandswould be used to enable access to additional spectrum by new U-NII devices while preservingthe mission capabilities of federal users. These current requirements that are implemented incertified and deployed equipment include transmitter power control (TPC) and dynamicfrequency selection (DFS) approaches. However, as directed by Congress, in addition to thesetechnical capabilities, NTIA also examined a range of known and proposed spectrum-sharingtechnologies and approaches, including sensing, geo-location database methods, and otherpotential co-existence measures and safeguards. Based on these known and proposed spectrum-sharing technologies and approaches, thisreport identifies a number of risk elements due to the likelihood of harmful interference fromlarge numbers of U-NII devices to protected federal systems in the 5350-5470 MHz and 5850-5925 MHz bands. The report discusses suggested mitigation strategies for each risk element.For example, the report identifies potential risks for federal airborne, ground-based, andshipborne radar systems related to changes in radar signal parameters or changes to U-NII devicedeployment and technical parameters, which current regulations may not be equipped toadequately address. Another risk element is that existing U-NII regulations were not developedto d