Wireless Industry Advises Caution on 24 GHz Emissions Limits

CTIA and other commenters urged the FCC to use caution as it considers adopting out-of-band emissions in the 24 GHz band aligned with limits adopted at the 2019 World Radiocommunication Conference, in filings posted Tuesday in docket 21-186. NTIA supports adoption of the WRC limits (see 2106280039). Comments were due Monday (see 2105260023). WRC-19 adopted emission limits not at the edge of the 24 GHz band, “but rather, as a limit on the total radiated power” wireless base and mobile stations can radiate into any 200 megahertz of the 23.6-24.0 GHz passive Earth Exploration Satellite Service (EESS) band,” CTIA said. WRC recommended two sets of limits for base stations and user equipment, one that applies now, and another set of limits for equipment brought into use after Sept. 1, CTIA noted. “As CTIA and other commenters have explained throughout this proceeding, the Commission’s existing OOBE limits are sufficient to protect EESS operations from interference,” the group said: The part used for wireless is separated by 250 MHz from “EESS passive sensing operations in the 23.6-24.0 GHz band.” The limits approved by the WRC “will provide even greater protection to passive EESS operations than is necessary, while still allowing for robust 5G deployment in the band," CTIA said. Nokia said its 24 GHz equipment can meet the initial limit of -33 dBW/200MHz before a Sept. 1, 2027, deadline and is working on the Phase 2 limit of -39 dBW/200MHz. “This effort requires close cooperation with radio frequency integrated circuit vendors to develop next generation of chipsets that can offer improved Power Amplifier linearity for the restrictive emission limit by the 2027 deadline,” Nokia said. The FCC’s current -13 dBm/MHz unwanted emissions limit below the lower 24.25 GHz edge of the band “should be maintained for mobile operations in the 24 GHz band because that limit provides adequate interference protection” of EESS passive systems, Qualcomm said. If the FCC adopts “substantially more stringent unwanted emissions limits” approved by the WRC “they should only be applied to mobile service base stations and handsets -- and not to any of the other operations” FCC rules allow, Qualcomm said. The FCC should be “cautious when it modifies its rules governing spectrum that has already been auctioned so as not to disrupt ongoing planning and deployment activities,” T-Mobile commented. The WRC limits “should apply only to mobile … and are not applicable to fixed operations permitted in the same band,” the carrier said. Opening the 26 GHz band for licensed use should be an FCC priority, CTIA said: “Because the Commission has already made spectrum in the 24 GHz and 28 GHz bands available for 5G, moving forward with the 26 GHz band is a rare opportunity to make a wide, contiguous swath of spectrum available for already globally harmonized, licensed use.”