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Spectrum Management

Protecting a Vital, Limited Resource

Overview

Many Federal agencies use radio frequency spectrum to perform vital operations. NTIA manages the Federal government's use of spectrum, ensuring that America's domestic and international spectrum needs are met while making efficient use of this limited resource. NTIA carries out this responsibility with assistance and advice from the Interdepartment Radio Advisory Committee and by:

  • establishing and issuing policy regarding allocations and regulations governing the Federal spectrum use;
  • developing plans for the peacetime and wartime use of the spectrum;
  • preparing for, participating in, and implementing the results of international radio conferences;
  • assigning frequencies;
  • maintaining spectrum use databases;
  • reviewing Federal agencies' new telecommunications systems and certifying that spectrum will be available;
  • providing the technical engineering expertise needed to perform specific spectrum resources assessments and automated computer capabilities needed to carry out these investigations;
  • participating in all aspects of the Federal government's communications related emergency readiness activities; and
  • participating in Federal government telecommunications and automated information systems security activities.

Related content


Using On-Shore Detected Radar Signal Power for Interference Protection of Off Shore Radar Receivers

Report ID
Technical Report TR-16-521
March 01, 2016
Frank H. Sanders; Edward F. Drocella Jr.; Robert L. Sole
Abstract

A spectrum sharing scheme is considered in which ship-based radar stations are operating in the same spectrum band as on-shore communication transmitters, and in which the communication transmitters will cause interference to the radar receivers when interference, I, to noise, N, ratios in the radar receivers exceed a given level (e.g., I/N >= -6 dB). The problem is that on-shore environmental sensing capability (ESC) monitors need to determine whether interference is occurring at off-shore radar receivers based only on information from the radars’ transmitters, with no information available from the victim radar receivers themselves. We describe an on-shore monitoring approach in which the principle of reciprocal propagation between the directions of radar-to-ESC and ESC-to-radar provides a simple go/no-go (single-bit) output from the ESCs to an associated Spectrum Access System (SAS) controlling the communication network, to perform on-shore channel changes for protection of the off-shore radar receivers. The ESC station outputs are based on a power-detection threshold of radar signals at the ESCs (e.g., -64 dBm peak-detected power in 1 MHz bandwidth). Examples are provided in which ship-based radar receivers are protected by a simple algorithm applied to a group of on-shore ESCs and a SAS controller for the terrestrial communication network channel frequencies.

Keywords: radar; radio propagation; antenna gain; spectrum sharing; spectrum access system (SAS); Citizens Broadband Radio Service Devices (CBSD); environmental sensing capability (ESC); interference monitoring

Intelligibility of Selected Speech Codecs in Frame-Erasure Conditions

Report ID
Technical Report TR-17-522
November 01, 2016
Andrew A. Catellier; Stephen D. Voran
Abstract

We describe the design, implementation, and analysis of a speech intelligibility test. The test included five codec modes, four frame-erasure rates, and two background noise environments, for a total of 40 conditions. The test protocol required twenty listeners to repeat all words that they heard in short messages with median length of seven words. Each condition was tested using approximately 1100 words total. Listeners’ responses were scored against the original message transcripts to produce a count of words correctly repeated and thus a measure of speech intelligibility. We present results that show exactly how this measure of speech intelligibility drops as frame-erasure rate increases for three of the five codec modes. The remaining two codec modes did not produce valid results due to defects in the reference software provided to us.

Keywords: background noise; speech coding; packet loss; speech intelligibility; audio coding; frame erasures; acoustic noise

Measured Emission Spectra of Selected AWS 3 LTE Transmitters

Report ID
Technical Report TR-18-528
December 01, 2017
Michael Frey; Geoffrey A. Sanders; Jolene Splett; John Ladbury; Frank H. Sanders; Azizollah Kord; Ryan Jacobs
Abstract

Version three of Advanced Wireless Services (AWS 3) radio systems will soon use spectrum that is adjacent to bands currently used by airborne telemetry links at U.S. government test and training ranges (TTRs). Spectrum sharing analyses need to be performed to determined how much off-tuning (number of megahertz) and distance separation (number of kilometers) are needed between AWS 3 transmitters and telemetry receiver stations to avoid harmful interference to those receivers. To complete these studies, detailed wide dynamic range emission spectrum measurements of representative models of the soon-to-be-deployed AWS 3 transmitters have been performed. This report describes those measurements, and the method used to obtain them. These measurements have been performed with over 100 decibels (dB) of dynamic range. The measurements have been collected in a variety of resolution bandwidths, transmitter modulations, and types of transmitter loading (i.e., number of resource blocks used) for two measurement detector modes. In general, AWS 3 eNB and UE transmitted emission spectra are found to be insensitive to variations in transmitter configurations. The measured power spectra of the eNBs and UEs vary in direct proportion to measurement (or receiver) bandwidth (i.e., as 10 log measurement bandwidth) with an approximate offset of about 10 dB between peak and average levels. The measurement results indicate that AWS 3 eNB and UE power spectra are suppressed by at least 100 dB in the adjacent telemetry bands for the devices tested. These results can now be factored into EMC analyses for AWS 3 transmitters operating in proximity to telemetry receivers.

The work described in this report was performed by the National Advanced Spectrum and Communications Test Network (NASCTN). Results were published simultaneously as NASCTN Report 4, NTIA Technical Report TR-18-528, and NIST Technical Note TN 1980.

Keywords: band sharing; emission spectrum; spectrum sharing; spectrum measurements; interference analysis; out-of-band (OOB) emissions; 1755-1780 MHz; 2155-2180 MHz; AWS-3; aeronautical mobile telemetry (AMT); Band 66; band sharing analysis; eNodeB (eNB); telemetry links; user equipment (UE)

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