Wireless technology, always an integral part of our everyday lives has now become more important, especially when it comes to the widespread use of cellular phones throughout the world. As the demand for mobile usage increases, wireless service providers are lobbying for more bandwidth within the finite radio frequency (RF) spectrum to service their growing number of customers. However, many other industries in defense, navigation, communications, weather, and science also use RF spectrum, causing prime frequency bands to become increasingly competitive and congested.
As demands for access to and use of the radio spectrum grow, the need for proactive spectrum management has become essential to minimize interference or misuse while meeting the wireless broadband needs of consumers and businesses as well as federal and local government needs. Currently, the Office of Spectrum Management (OSM) at the National Telecommunications and Information Administration (NTIA), oversees the federal government's use of the spectrum while the Federal Communications Commission (FCC) manages all non-federal use.
Crucial Spectrum Regulatory Issues
The Air Force Space and Missile Systems Center relies on spectrum management experts like The Aerospace Corporation for analysis, testing, recommendations, and expertise when it comes to making decisions on managing, sharing, and reallocating segments of the spectrum. Potential conflicts can arise between private industry and government interests, especially since the spectrum is a finite resource so at times, users must share bands within the spectrum. Sharing in a technically complex environment is difficult at best and can present numerous spectrum regulatory issues. Conflicts between co-sharing users at times have to be addressed using legal recourse.
In one instance, mobile wireless providers’ need for more spectrum bandwidth has encroached on government weather satellites’ existing spectrum territory, leaving regulators with the difficult choice to answer the question, “Which is more important?” Allocating more spectrum to the wireless industry so that it can increase business, which would potentially translate to more jobs and customer service, or maintaining the direct broadcast and data relay from weather satellites that provide the public and weather industry with forecasts, disaster and flood warnings, and crucial emergency management information?
Spectrum Management in the L-Band
The portion of the spectrum that extends from 1000 to 2000 MHz is called “L-band”, whose signals are generally easy to process and do not require expensive equipment due to their lower frequencies. They have less disruption due to weather issues in the atmosphere, so L-band is currently used by weather satellites, GPS satellites, aircraft surveillance systems, mobile operators, and a multitude of other users.
One of the most important weather satellite constellations in L-band are the Geostationary Operational Environmental Satellites (GOES) operated by the National Oceanic and Atmospheric Administration (NOAA). NOAA is a scientific agency within the United States Department of Commerce that oversees and reports on the conditions of the oceans and the atmosphere. GOES satellites are used for a multitude of functions in addition to sourcing information necessary for critical meteorological issues. They are used for hurricane, tornado, and flood warnings; managing firefighting efforts during wildfires; protecting the electrical power grid from damage induced by solar storms; routing aircraft away from volcanic ash and excessive natural radiation levels; and much more.
As a result of the Advanced Wireless Auction-3 (AWS-3) in 2015, wireless carriers were able to purchase portions of the L-band spectrum. A relatively small, but important band sold at auction was the 1695 to 1710-MHz band, primarily utilized by the NOAA polar-orbiting and geostationary weather satellites. This would have been problematic for existing weather satellites such as GOES because a mobile signal can overpower a GOES downlink signal.
Spectrum Management Team Provides RF Spectrum Solutions
To solve this potential conflict, the NOAA turned to The Aerospace Corporation spectrum management team to assist in developing a solution. The team reviews domestic and international spectrum regulatory issues and provides guidance with respect to the proper selection of compatible spectrum for both federal and non-federal space customers.
Aerospace spectrum management experts used a series of mathematical calculations, computer simulations, and field measurements that resulted in recommendations for a conceptual architecture for an RFI monitoring capability to detect signals from handheld devices that could cause interference to the GOES receive Earth stations.
Based on its research, Aerospace also offered suggestions for the location of cell tower placements around NOAA and National Weather Service ground stations to minimize the interference with weather satellite receiver sites. These recommended solutions allow the wireless carriers and the GOES weather satellites to share the spectrum without harmful interference and conflict.
Although the RF spectrum is invisible to the human eye, it is one of our most valuable energy resources. Like many natural resources, the spectrum is limited and must be used wisely. As technology evolves and more demand is created for RF spectrum usage and sharing, the need for spectrum management becomes progressively more important to ensure everyone has the opportunity to benefit from this precious resource.