The new emission limits in the 24 GHz band adopted by the FCC prioritize protecting the passive 23.6-24.0 GHz band used for vital Earth Exploration Satellite Service (EESS) observations while enabling the growth of next-generation wireless services.
The FCC has implemented a two-phase approach to align its regulations with the Resolution 750 limits set by WRC-19.
*Phase 1 limits (-33 dBW/200 MHz for base stations and -29 dBW/200 MHz for mobile stations) are effective immediately.
*Phase 2 limits, which are stricter (-39 dBW/200 MHz for base stations and -35 dBW/200 MHz for mobile stations), will apply to equipment brought into use after September 1, 2027. This timetable balances protection of EESS with 24 GHz band development.
Key Decisions and Impacts:
*All mobile operations in the 24 GHz band are subject to Resolution 750 limits. This ensures consistent protection for the passive band as the definition of “mobile” encompasses various devices and applications.
*The FCC chose not to impose stricter limits than Resolution 750 despite concerns from the scientific community. The record lacked technical data supporting stricter limits, and NTIA, NOAA, and NASA endorsed Resolution 750. Stricter limits could hinder the development of next-generation wireless services due to the power requirements for millimeter wave spectrum.
*Fixed operations (point-to-point and point-to-multipoint) are exempt from Resolution 750 limits. This is because Resolution 750, as adopted by the ITU, only applies to mobile operations. The FCC will monitor fixed operations for potential issues.
*Indoor small-cell systems are not exempt from Resolution 750 limits despite arguments for an exemption due to building attenuation.
*Compliance with emission limits can be demonstrated using both TRP and maximum conducted output power measurements. This provides flexibility for equipment manufacturers and is consistent with practices in other UMFUS bands. Conductive power measurements are considered more conservative than TRP.
Further Considerations:
*While Phase 1 equipment brought into use before September 1, 2027, can continue operating indefinitely, any modifications or replacements after that date must comply with Phase 2 limits. This ensures that future deployments adhere to the stricter standards.
*Routine modifications that do not affect emission characteristics are exempt from the Phase 2 requirement.*The FCC encourages licensees to avoid uptilt in fixed operations to minimize potential interference with EESS satellites.
Impact on Type Approval and Market Access Requirements? – Yes
Impact on Imports, Customs, Trade, or Market Surveillance? – No
Impact on Spectrum Management? – Yes
Impact on Technical Standards? – Yes
