FCC 6 GHz Order, FNPRM Got Many Changes From Draft
The FCC’s final order allowing unlicensed devices to share 1,200 MHz of 6 GHz spectrum has many changes from the draft. They go beyond additional questions mentioned by commissioners voting 5-0 Thursday (see 2004230059), based on our side-by-side analysis. A section on formation of a multistakeholder group to address technical and operational issues with the automated frequency control (AFC) system was moved within the order. Most changes are technical and don’t address concerns raised by 6 GHz incumbents. The item, released Friday, is 26 paragraphs and 11 pages longer than the draft.
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The Further NPRM contains a new section on mobile standard-power access point operations. “We seek comment on whether to allow standard-power access points, under AFC control, to be used in mobile applications under rules similar to those for personal/portable white space devices,” the draft said: “Such usage would expand the area over which unlicensed 6 GHz devices can operate to deliver additional benefits to the American public.” Also new, a section on higher power limits and antenna directivity for standard-power access points. “We seek comment on the appropriate technical parameters and limits that would be associated with 6 GHz point-to-point operation,” the FNPRM said: “How would we ensure that incumbent operations will be protected from unlicensed devices operating at higher power levels?”
The FNPRM asked: “We seek comment on permitting mobile AFC controlled standard-power access point operation and on whether to allow higher power levels for AFC controlled standard power access points used in fixed point-to-point applications.” The final order asked: “Can the analyses performed for indoor low power devices inform how we proceed here?”
Asking about power levels for outdoor devices, the draft said that “we are generally considering power levels in the range of 4 dBm to 14 dBm [effective isotropic radiated power] and a corresponding power spectral density referenced to a 160-megahertz channel.” The final rule is more open: “Similar to the rules we are adopting for indoor low power devices, we anticipate requiring devices to meet a power spectral density requirement, which inherently places a maximum on radiated power. Do commenters support this approach?”
A section on propagation models had changes. The FCC added language saying it studied various models and “whether several propagation models accounting for different conditions and distances should be adopted.” In a section on propagation analysis, the final order includes additional information. It adopted "the free space pathloss model for distances less than 30 meters,” the FCC said: “This model generates the greatest possible path loss to account for the possibility of direct line-of-sight from a standard-power access point to a microwave receiver.” The final version added: “If detailed local information is not available, we believe the ‘Village Centre’ clutter category should be used as a default.”
In a section on AFC device registration, the FCC now says registration “provides another layer of protection by ensuring only authorized devices access the spectrum and by easing the process of mitigating harmful interference if it occurs.” The draft said only it “allows for” additional protection. The FCC turned down an NFL request to expand the scope of device registration to include the league's stadiums and other venues (see 2004140039).
The order disagreed with a “recent filing” by CTIA countering data in a CableLabs technical study that models the interference potential of low-power indoor unlicensed devices to microwave receivers. “According to CTIA, the only way the 0.4% activity factor and 70% utilization rate could be reconciled is if multiple Wi-Fi access points are transmitting in the same area, which CTIA argues would need to be included in the CableLabs computer simulation,” the order said. The text also dismissed a Southern Co. technical study.
Another new paragraph noted that AT&T, CTIA and other representatives of fixed microwave services “express concern that even if the Commission concludes that the probability of harmful interference from indoor low-power operations is low, harmful interference nonetheless may occur, and the Order does not go far enough to ensuring that to the extent low-power device(s) actually cause harmful interference to incumbent operations, the interfering devices can be identified.” The order dismissed the concerns: “In the unlikely event that harmful interference does occur, our Part 15 rules in section 15.5 (b)-(c) require that such operations cease, and the Commission’s Enforcement Bureau has the ability to investigate” and act.
In a section on fixed satellite services, the final order added: “We agree with Sirius XM, Intelsat, and SES that there will be negligible interference to satellite receivers from low-power indoor unlicensed devices.”