NTIA Advises FCC Caution on Interference Temperatures
NTIA told the FCC it should go slow on development of regulations allowing for use of interference temperatures as a metric -- a concept the Office of Engineering & Technology says could help measure and manage interference opening up more spectrum to unlicensed use for such things as wireless Internet.
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NTIA disagreed with the FCC on the key issue of where on the radio spectrum tests should take place. NTIA said if the concept is tested it should be in spectrum returned by govt. users, such as the 3650-3700 MHz band. FCC had proposed testing within the fixed (FS) and fixed satellite service (FSS) uplink band at 6525-6700 MHz and the FS, FSS, and BAYCARS band at 12.75-13.25 GHz (excluding 13.15-13.2125 GHz).
Several opponents of the use of interference temperatures said Wed. they were pleased with NTIA’s cautious stance. NTIA, in effect, filed late, since comments were due in early April and replies in May. But the agency is given latitude because of its status in representing important govt. spectrum interests. The filing ran 67 pages without appendixes.
The NTIA filing reflects industry concerns that the FCC has not gathered enough “hard, empirical” data to proceed with testing, said a regulatory attorney opposed to the use of interference temperatures as a metric. “NTIA is saying go slow…. They're not saying no. They're just saying go slow,” the attorney said. “The NTIA is saying this is something that needs further consideration. It might be a good idea in some of the bands but not all frequency bands.”
“We hope [interference temperature] dies a quiet death,” said an industry official who filed against the use of interference temperatures. “I'm forever surprised to see it keep popping up. To the extent that NTIA has raised red flags we're all for them.”
OET Chief Edmond Thomas continues to support the concept, which was one recommendations of the Spectrum Policy Task Force. Thomas has argued that the opposition is typical of spectrum incumbents on such issues and that FCC will test in only limited, “very safe” bands (CD May 19 p1).
The notice of inquiry on interference temperatures “identifies many technically challenging issues that must be addressed before the interference temperature model can be implemented in a frequency band,” NTIA said. “These technical issues include but are not limited to: Development of radio service specific reference receiver parameters; development of radio service specific maximum permissible interference limits and operational scenarios; and measurement of the existing radio frequency signal environment in order to establish a proper baseline.” Until the issues are addressed fully, as well as the rights and responsibilities of spectrum users, “widespread implementation of the interference temperature model will not be possible,” NTIA said.
Interference temperature particularly shouldn’t be applied for spectrum covered by Section 15.205 of the Commission’s rules, which includes aeronautical radionavigation, radio astronomy, satellite downlinks and other sensitive uses, the agency said. “It is difficult to envision how the interference temperature model as described… can be implemented to manage interference in the restricted frequency bands without establishing interference temperature limits that are so low that any commercial wireless device would be rendered useless,” NTIA said.