Rulemaking petition objects to satellite earth stations’ setting aside frequencies they may never need.

Managing the radio spectrum is one of the FCC’s toughest, least appreciated jobs. The goal is to squeeze in as many users as possible, with the least interference among them. Often the FCC can get more out of a frequency band by sharing it among different kinds of users. Parts of the Wi-Fi bands, for example, are shared with amateur radio licensees and federal radars.

There is such a sharing arrangement between satellite and fixed microwave users. Satellite earth stations are those big dishes aimed toward the sky; microwave antennas are the sideways-aimed dishes or cylinders on towers and buildings. Decades ago, someone reasoned that their respectively vertical and horizontal beams should be able to coexist without interference. In practice things are more complex (as things usually are in practice), with interference between the two services being a real possibility.

An applicant for a license in either service must go through “frequency coordination”: a procedure to ensure the proposed microwave link or satellite link will not interfere with an incumbent in either service. A database of existing licensees makes this possible. At the time of licensing, the new link goes into the database for protection against later arrivals.

There is an important difference in how microwave and satellite applicants handle this last step. A microwave applicant puts into the database only the frequencies it will actually use, and only the location and direction of the beam between the transmitter and receiver it intends to build. A satellite applicant, in contrast, routinely puts into the database its entire frequency band – hundreds of megahertz – and all possible directions from the earth station to any satellite that could be in a stationary orbit. This allows the earth station later to shift to any frequency in the band, and to aim at any satellite, without risk of interference. The satellite operators say they need this flexibility because they must design their systems years before launch; modifications to satellite hardware are impossible after launch; and customers’ needs may change during the lifetime of the satellite. On the other hand, the earth stations’ routine “over-coordination” locks out spectrum that microwave operators may need, even if the earth station is not using it and has no plans to use it.

The Fixed Wireless Communications Coalition (FWCC) – a group of fixed microwave manufacturers, users, and others in the industry – wants the FCC to change the rules. It asks that a satellite earth station be allowed to coordinate only the frequencies and directions for which it has immediate need. But the earth station could also earmark any amount of additional frequencies and directions as “growth capacity” for possible future use. A microwave operator could use these only as a last resort, if nothing else is available, and would first have to consult with the earth station operator on how to be least disruptive to the earth station’s possible future plans. Acknowledging that some earth stations must be able to access multiple satellites and add and change satellites on short notice, the FWCC proposes that these be allowed to apply for a waiver permitting them to coordinate additional frequencies and directions with no time limit on when they might be used.

Overall, the FWCC argues its plan will increase the available spectrum with minimum negative impact on earth station operators. Satellite interests may disagree.

The FWCC petition is here; the FCC’s public notice of the petition is here. Comments are due on Monday, January 9, and reply comments on Tuesday, January 24. File comments at this website; field, enter RM-11778 in the “Proceeding(s)” field.