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Enhancing Spectrum Utilization
Enhancing Spectrum Utilization
To support the Department of Commerce strategic objective to increase scientific knowledge and provide information to stakeholders to support economic growth and to improve innovation, technology, and public safety, NTIA undertook a strategic initiative to meet the increasing radio spectrum needs of the United States, both for Federal and commercial users, as efficiently and effectively as possible. ITS is tasked to promote the development of innovative spectrum sharing technologies by conducting the spectrum sharing test bed pilot program and by conducting, through ITS’s reimbursable authority, engineering studies on behalf of other Federal agencies on in-band and adjacent band interference and interference mitigation techniques. Research to enable the fullest spectrum utilization encompasses interference analysis and mitigation, spectrum measurements, and national and international standards development.
Interference analysis and mitigation studies provide the data needed to continuously improve the technologies that allow users to gracefully share the same radio space or operate in adjacent bands. Electromagnetic compatibility (EMC) studies characterize the emissions of different radio devices and develop algorithms for detection and avoidance based on those characteristics, so that equipment in shared bands can be programmed to limit interference by recognizing and avoiding the emissions of other devices. Ideally, these studies are carried out prospectively, while new equipment or new sharing regulations are still under development. Sometimes, however, they are needed to trace to its root cause interference experienced in situations that were previously thought to be safe for sharing and to devise mitigation strategies.
While EMC studies characterize the emissions of different devices, spectrum measurements characterize the radio space in which they operate. Spectrum measurements do not identify individual transmitters, but catalog the amount and nature of the electromagnetic radiation present in the radio spectrum over a specified period of time in a specified geographic location. This description of the existing radio spectrum environment is used to identify opportunities for increased utilization as well as to describe the background radio noise against which intentional transmissions will have to be made secure and resilient.
Radio waves are made to carry information by varying the wave’s amplitude, frequency, and phase within a frequency band. They range from hundreds of meters to about one millimeter in length, corresponding to about 300 GHz to 3 kHz in frequency, and there are significant variations in the behavior of waves of different frequencies. This is why certain frequencies are more desirable “real estate” for certain purposes. To discover innovative ways to cram more information streams into each segment of the spectrum, and to make those streams resilient and robust no matter what frequency they travel on, we must continuously deepen our understanding of the behavior of radio waves and the radio environment.
Spectrum measurements also describe the current occupancy of different bands. This allows regulators to plan realistic strategies for increasing utilization, and it allows product designers to plan strategies to protect desired transmissions from other traffic in the neighborhood. While the behavior of radio waves is a physical constant that can be measured almost anywhere, occupancy varies geographically. Not only is the spectrum predictably more crowded in urban than in rural areas, but the frequencies and amplitudes of the traffic vary with proximity to airports, littoral areas, centers of research, etc.
National and International Standards Development
Data from ITS research is also used to support the development of national and international standards for radio devices. Strong and unbiased standards support fair competition in the information and communications technology sector. Technical standards establish common norms for technical systems—uniform engineering criteria, methods, processes, and practices that promote competition and interoperability. Standards define the parameters of permissible emissions from different transmitters to reduce the probability that unwanted radiation interferes with other users. Standards define the characteristics of transmission envelopes so that devices from different manufacturers can interoperate predictably. Participation in standards development organizations (SDOs) helps influence domestic and international telecommunications standards and policies to support U.S. industry and the Administration’s spectrum sharing initiatives and needs.
In cooperation with other interested U.S. government agencies and industry groups, ITS participates in national and international telecommunication standards development. ITS submits, and coordinates the formal review and approval of, recommendations on emerging mobile radio technologies, broadband network performance, radio propagation prediction, and radar systems. Under agency reimbursable agreements, ITS staff also continue to support other Federal agencies with development of telecommunication specifications, standards, proof of concept and demonstration measurements, interoperability analyses, technical and economic impact assessments, and prototype development.