Spectrum for Broadband

Description

On March 8, 2011, the Federal Communications Commission released a Public Notice seeking comment on the steps it can take to best promote wireless broadband deployment in the 1695-1710 MHz and 3550 3650 MHz bands recently identified by the National Telecommunications and Information Administration (NTIA) for accommodating wireless broadband.

The FCC also seeks input to inform ongoing assessment of several additional bands NTIA has identified for potential deployment of wireless broadband. These bands include the 1755 1850 MHz, 4200 4220 MHz and 4380-4400 MHz bands, and others identified by NTIA as candidates for commercial use.
The FCC seeks specific comment on whether and to what extent these bands could be made available for broadband deployment. It is particularly interested in comments on the following issues:

• How do the technical assumptions upon which NTIA based its analyses affect how broadband services could be deployed in each band?
• How do the conditions placed on the bands (e.g., exclusion zones) affect their usefulness for broadband deployment?
• What types of broadband technologies could be deployed in these bands and is equipment readily available? Does this equipment meet the technical assumptions in NTIA's analyses? If not, how would the use of different technologies affect the availability of each band for broadband use?
• Will future broadband services require paired spectrum bands and, if so, what are the most suitable band pairings for the spectrum identified by NTIA? If the spectrum identified by NTIA is not paired, what broadband technologies might be deployed?
• Could broadband services share use of each band with Federal users and what techniques would be most effective for sharing (e.g., coordination in time, geography, or policy, and / or the use of cognitive technologies)? If sharing would not be feasible, what process should be used to relocate or phase out incumbent users (both Federal and non-Federal) and what are candidate relocation frequency bands?

Issues

1695-1710 MHz. The 1695-1710 MHz band is used for downlinks from certain weather satellites that are administered by the National Oceanographic and Atmospheric Administration (NOAA) for weather forecasting, storm tracking, and hazard warnings. NTIA recommends that the FCC allocate the band to the non-Federal mobile service and that we establish 72 to 121 km-radii exclusion zones to protect 18 Federal earth stations from harmful interference that may be caused by the new mobile service transmitters.

In June 2010, the FCC sought comment on the potential for use of the larger 1675-1710 MHz band as part of this docket. Accordingly, and based on the existing record the FCC has developed, the asks commenters to specifically address future broadband operations in the 1695-1710 MHz portion of the band that was identified in NTIA’s January 2011 letter.

3550-3650 MHz. This 100 megahertz spectrum block is part of the larger 3500-3650 MHz band, which is allocated to the radiolocation and aeronautical radionavigation (ground-based) services on a primary basis for Federal use and to the radiolocation service on a secondary basis for non Federal use. The 3600 3650 MHz band is also allocated to the fixed-satellite service (space-to-Earth) on a primary basis for non-Federal use, limited to international inter-continental systems.

Under the NTIA proposal, non-Federal users would be prohibited from operating up to as much as 570 km from the U.S. coastline, and additional exclusion zones would be established for ten locations. NTIA also recommends that the FCC require the use of radio frequency front-end filters with between 30 and 40 decibels of attenuation at 3500 MHz in order to protect the new mobile and base station receivers from high power radar interference.

The exclusion zones along the coasts were established due to potential interference from federal ship borne radars to commercial mobile systems and are based on known protection levels of the broadband system receivers. We seek comment on whether the receiver protection levels used in the analyses are appropriate for next generation broadband systems and whether potential commercial users would be able to take steps to operate with smaller exclusion zones. Would commercial users be willing to accept the increased interference risk that comes with smaller or no exclusion zones? How could this increased interference risk be addressed in our rules? The FCC seeks specific comment on whether the error detection and correction techniques employed in modern digital receivers can reduce the effects of pulsed interference from radar signals. Would commercial users be willing to accept receiver standards to allow better sharing with high powered adjacent band Federal systems? Additionally there will be periods when the radars are not operating. We invite comment as to whether there are techniques that can be developed to enable co-existence with the ship-borne radars, such as dynamic spectrum access to avoid use of this spectrum when interference is present and instead move communications traffic to other spectrum.

The FCC notes that NTIA selected the 3550 3650 MHz band because Worldwide Interoperability for Microwave Access (WiMAX) equipment has been developed for the band. We seek information on the extent to which the technical considerations that apply to the adjacent 3650-3700 MHz band are applicable here. For example, should primary fixed-satellite service use of the 3600-3650 MHz band be restricted to currently licensed earth stations, and should such stations be protected on the same basis as the “grandfathered” primary stations in the 3650-3700 MHz band?

1755-1850 MHz. This band is allocated to the fixed, mobile, and space operation (Earth to-space) services on a primary basis for Federal use, and is used by the Department of Defense (DOD), Federal law enforcement agencies, and other agencies for a variety of satellite, surveillance, aeronautical operations, fixed microwave and other operations. For example, some of the 20 channels that are used to control Federal satellite systems are within the 1755-1780 MHz band segment.

In the Fast Track Report, NTIA stated that it selected the 1755-1780 MHz segment for its potential to be paired with the 2155-2180 MHz band. However, given the number of Federal users in the band, the diversity of Federal uses, and the need to find replacement spectrum for operations that would have to be relocated from the band if it were to be made available for wireless broadband, a rigorous review of the 1755-1780 MHz band has not yet been completed. We note, however, that both NTIA and individual Federal agencies have previously released reports, in 2000 and 2001, that address use of the 1755-1850 MHz band. These reports indicate that the satellite uplink operations could be in the band for approximately another twenty years. They also indicate that co-channel sharing was not feasible due to interference from the satellite Earth station uplink transmissions to mobile system receivers. We seek comment on whether establishing exclusion zones around the satellite Earth stations to protect wireless broadband receivers would result in the most efficient use of this spectrum recognizing that the receiver protection levels for the commercial systems in the earlier reports, and the resulting exclusion zones may no longer be applicable. Alternatively, we seek comment on whether broadband systems could operate more efficiently on a co-channel, co-coverage basis with the Earth stations using time sharing techniques. Commenters are strongly encouraged to provide supporting technical information for any geographic and time sharing techniques that are, or soon-to-be commercially available that could be applied in this spectrum to make it available for mobile broadband use.

4200-4220 and 4380-4400 MHz. These band segments are part of the 4200-4400 MHz band that is used worldwide for radio altimeters on aircraft. In the Fast Track Report, NTIA decided to further review this 40 megahertz of spectrum to explore to what extent radio altimeters operate in these particular band segments. We specifically invite comment on the extent to which radio altimeters are deployed and used in commercial and private aircraft. What sources of information are available on the technical operating characteristics of the radio altimeter transmitters and receivers (e.g., center frequency, bandwidth, modulation)? Because the need for international regulatory action by the International Telecommunication Union and the International Civil Aviation Organization means that this spectrum cannot be made available for broadband use in the United States before 2016, NTIA also plans to work to obtain international approval for reallocating this spectrum by that date.

Additional Frequency Bands. We also seek comment on the Federal and shared-use bands identified as part of NTIA’s Ten-Year Plan. Which of these bands appear to be most viable candidates for commercial broadband use and why? Is any of this spectrum well suited for the relocation of incumbent services in order to open broadband opportunities in other bands? Are there bands or specific frequencies that would be beneficial from an international harmonization perspective? What technical criteria should be used to characterize the systems that might be deployed in these bands for purposes of analyses?