ARRL has commented in “strong opposition” to a Petition for Rulemaking by RADWIN Ltd. that seeks to amend certain Part 15 rules to permit point-to-multipoint (P2MP) communication services in portions of the 5 GHz band, at power levels now permitted only for point-to-point unlicensed systems. ARRL has focused its concern on proposed high-power P2MP operation in the band 5.725 – 5.850 GHz, but points out that the entire 5.650 – 5.925 GHz allocation has been “subjected to a continuing series of overlays domestically” for more than 2 decades. Amateur Radio is secondary to military radars on the band.

ARRL said the Amateur Radio national “weak-signal” calling frequency of 5.760.1 GHz already has experienced a “very substantial” rise in ambient noise in many areas that has significantly affected Amateur Radio operation in the 200 kHz centered on that frequency, where extremely weak received signal levels are typical. Only low-density usage and the low-power levels permitted for unlicensed national information infrastructure (U-NII) devices have sustained “a good deal of compatibility” between Amateur Radio and U-NII devices at 5 GHz, ARRL said.

“It is quite obvious that RADWIN’s proposal for simultaneous point-to-multipoint transmission, with higher input power and [effective isotropic radiated power (EIRP)], using an electronic steerable antenna system, presents an exceptionally high interference potential to ongoing, weak-signal Amateur Radio Service communications,” ARRL said in its comments filed on July 30. With users located “at all points of the compass from the distribution point,” ARRL said, the potential for interference to Amateur Radio “is much greater.” Greater yet, ARRL noted, is the potential of interference to users of RADWIN’s system.

ARRL said the FCC “has no idea at all” about aggregate noise levels in the 5 GHz band in general, while Amateur Radio and Amateur Satellite users have reported increased ambient noise levels in the band, especially near 5.760 GHz. “Both the Petition and the technical statement accompanying the Petition are silent on potential interaction between P2MP simultaneous transmission systems operating at high power, and any Amateur Radio facility,” ARRL said. “As a result, the petition is fatally flawed and should be dismissed, relative to the 5.725 – 5.850 GHz band.”

ARRL asserted that the FCC lacks jurisdiction to authorize Part 15 device operation by rule, “absent a specific finding that the device will not predictably cause interference.” Unlicensed, very low-power Part 15 devices may not cause interference to licensed services and must accept any interference caused by a licensed station and must shut down if notified by the FCC that the device is causing harmful interference.

ARRL said RADWIN’s Petition not only is flawed, but fails to address the issue of compatibility between the proposed high-power P2MP Part 15 operation and individual stations in incumbent primary and secondary services.

“It is long past time that petitioners such as RADWIN provide in their rulemaking petitions dealing with Part 15 rules enough data to allow the Commission to make an evaluation that fulfills its obligation under the Communications Act,” ARRL concluded. “RADWIN’s Petition must be dismissed as one which fails to provide an adequate justification for the relief requested.”