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FCC Considers MSS Use of 2483.5-2500 MHz for ATC Stations

The FCC made significant changes to its allocation of frequencies for “Big LEO” mobile satellite service (MSS) systems in the 1.6 GHz and 2.4 GHz bands last week. LEO is an abbreviation for “low Earth orbit.” The most significant change was eliminating most of the shared spectrum and allocating each of the two current LEO operators, Globalstar and Iridium Satellite, 7.775 MHz of L-band spectrum. Globalstar uses code division multiple access (CDMA) and Iridium uses time division multiple access (TDMA) technology, making the two systems incompatible and making spectrum sharing difficult. To resolve certain technical issues, the FCC required the two systems to share 0.95 MHz of L-band spectrum.

Of interest to broadcasters, Globalstar is seeking authority to operate an ancillary terrestrial component (ATC) in the 2495-2500 MHz band. This would require sharing spectrum between the broadband radio service (BRS) and educational broadband radio service (EBS). It would also impact broadcast auxiliary service use of the 2483.5-2500 MHz band. SBE filed comments in the proceeding noting one solution would be to “re-pack” the BAS 2.4 GHz spectrum into narrower channels, as is being done with the 2 GHz BAS spectrum.

The FCC said, “it is not feasible or in the public interest to authorize ATC in the portion of the S-band that Big LEO MSS shares with the fixed and mobile services, at 2495-2500 MHz,” but invited comments challenging that conclusion. This spectrum is part of grandfathered BAS channel A10. New licenses are not being issued for this channel, although many stations have licenses that any ATC operation would have to protect. In its Big LEO Spectrum Sharing Order, the FCC allowed MSS ATC facilities to use frequencies between 2487.5 and 2493.0 MHz.

In last week’s action, the FCC said, “if we expand the authorized ATC spectrum to a lower limit of 2483.5 MHz, this lower limit would be adjacent to BAS Channel A9. We seek comment on what technical standards, such as out-of-band emission limits or power limits, would be necessary to prevent interference from ATC to BAS Channel A9.” The FCC said its Notice of Proposed Rulemaking “is not intended to prejudice or influence any action the commission may take with regard to SBE’s Petition for Reconsideration in the Big LEO Order on Reconsideration and AWS 5th MO&O proceeding.” Comments on MSS operators’ use of 2.4 GHz spectrum for ATC should be filed under IB Docket 07-253.

For additional information, refer to the Second Order on Reconsideration, Second Report and Order and Notice of Proposed Rulemaking regarding spectrum and service rules for ancillary terrestrial components in the 1.6 and 2.4 GHz band and review of the spectrum sharing plan among nongeostationary satellite orbit mobile satellite service systems in the 1.6 and 2.4 GHz bands.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.