Scope and Impact of Regulation

This regulation, issued by the Federal Communications Commission (FCC) under GN Docket Nos. 18–122 and 25–59, reconfigures the 3.98–4.2 GHz band (Upper C-band) to expand terrestrial wireless flexible use in the contiguous United States. It repurposes 160 megahertz of spectrum for mobile services, primarily to support 5G and next-generation wireless ecosystems. This action impacts radio device manufacturers by incorporating these frequencies into the "3.7 GHz Service," necessitating compliance with updated technical and coexistence rules designed to protect incumbent satellite services and adjacent-band aeronautical radio altimeters.

Permitted Radio Bands and Technical Parameters

The regulation establishes the following band plan and technical requirements for terrestrial operations:

• Designated Band: 3.7–4.14 GHz (consisting of 20-megahertz unpaired blocks).
• Guard Band: 4.14–4.16 GHz (reserved to protect FSS operations).
• Designated Use: Fixed and Mobile services (except aeronautical mobile).
• Power Limits (Fixed/Base Stations):
  • Non-rural areas: 1640 Watts/MHz EIRP.
  • Rural areas: 3280 Watts/MHz EIRP.
  • Power is calculated as the aggregate of all antenna elements in a sector.
• Power Limits (Mobile/Portable Devices): Limited to 2 Watts EIRP. Devices must employ power control to the minimum necessary for successful communication.
• Antenna Height Restriction: Base stations operating in the 3980–4140 MHz range are restricted to a maximum height of 450 feet (137 meters) above ground level.
• Out-of-Band Emissions (OOBE):
  • General limit: -13 dBm/MHz conducted at the channel edge.
  • Protection for 4.2–4.4 GHz (Radio Altimeters): Fixed/base stations must suppress emissions to either -28.4 dBm/MHz EIRP or -46 dBm/MHz conducted.

Specific Exemptions and Restrictions

The reconfiguration and new terrestrial licensing rules apply only to the contiguous United States (CONUS) and the District of Columbia. The following areas are specifically excluded from terrestrial wireless flexible use licensing at this time, preserving the status quo for Fixed Satellite Service (FSS) and Fixed Service (FS) allocations:

• Alaska and Hawaii
• Puerto Rico and the US Virgin Islands
• Guam, Northern Mariana Islands, and American Samoa
• The Gulf of Mexico

Additionally, while the 4.14–4.16 GHz band is allocated for mobile services, no service rules have been established for its use other than its function as a guard band.

Conformity Assessment and Testing Procedures

Manufacturers must adhere to the equipment authorization procedures specified in 47 CFR Part 2 and the service-specific rules in Part 27. Key requirements include:

• Equipment Authorization: Devices must meet RF safety limits and minimize interference as per § 27.51 and Part 1, Subpart BB.
• Interoperability Requirement: New client devices must be capable of operating across the entire 3.7–4.14 GHz band using the same air interfaces.
• Interoperability Deadline: Starting December 31, 2030, all new mobile and portable stations must be fully interoperable across the entire band. Equipment authorized prior to this date that cannot be upgraded may remain in service for its useful life.
• Service Area Boundary Limits: Licensees must ensure a power flux density (PFD) limit of -76 dBm/m²/MHz at a height of 1.5 meters above ground at their service area borders.

Labeling Requirements

The regulation requires that all devices comply with standard FCC equipment authorization labeling. While no unique label text is introduced by this specific order, devices must be authorized under 47 CFR Part 27, which necessitates the application of an FCC Identifier (FCC ID) and the standard compliance statements required for intentional radiators. Supporting documentation for performance benchmarks must include electronic coverage maps and propagation models used to certify reliable signal coverage.

Modification of Existing Regulations

This regulation modifies the following rules and previous orders:

• 47 CFR Part 25: Replaces the FSS allocation with mobile services in the 4.0–4.16 GHz range within CONUS. It restricts new FSS earth station applications in this range.
• 47 CFR Part 27: Expands the "3.7 GHz Service" definition to include the 3700–4140 MHz band.
• Modification of 2020 C-band R&O: This order builds upon and modifies the "Expanding Flexible Use of the 3.7 to 4.2 GHz Band" (GN Docket No. 18-122; FCC 20-22) by repurposing an additional 160 MHz of the Upper C-band originally reserved for FSS in the previous transition.
• U.S. Table of Frequency Allocations: Modifies footnote NG457A to limit Earth Stations on Vessels (ESVs) coordination to the 4.16–4.2 GHz band.