Opposition to the Proposal

The ex parte from Apple et al concludes that ‘RKF’s findings are clear: unlicensed services can successfully coexist with the primary services present in the 6 GHz band.’. This conclusion is misleading as the RKF study has since been discredited. The study is founded on a host of incorrect assumptions. Opposition to Apple et al’s proposal has been submitted to the FCC by a number of parties including AT&T, the FWCC (Fixed Wireless Communications Coalition) and the NSMA (National Spectrum Management Association). Here we consider some of the key points raised by reviews of the RKF study.

The FWCC opposition ex parte, March 2018, is rich in technical detail and includes analysis of existing, real world microwave receivers in eight key cities across the United States. They considered the impact to these receivers in the presence of uncontrolled, unlicensed devices operating under the conditions proposed by Apple et al. The FWCC study found that uncontrolled use of RLANs at the power levels and numbers proposed would result in ‘widespread harmful interference’ to microwave receivers. In fact, the study demonstrates that every receiver within the scope of the eight-city study would experience some level of interference. Further, 70% of the receivers would suffer a high level of interference that would degrade fade margin by 10dB or greater. One in thirty receivers would see extreme interference (40dB or greater) that would effectively disable them. The FWCC’s ex parte also points to one of the most concerning issues regarding spectrum sharing with unlicensed devices; the fact that there is obviously no record of ownership or location of the devices, making it virtually impossible to identify sources of interference. The FWCC study concludes that Apple et al/RKF cannot prove non-interference to incumbent services and so the FCC must reject the proposal.

AT&T’s March 2018 analysis of RKF’s study raises similar concerns, including the difficulties surrounding the identification of interferers, due to lack of records regarding location/owner and also the fact that interference may not be consistent. They dispute several of RKF’s assumptions, including the distribution of power/height/number of RLAN’s; RKF’s study averages RLAN power by geography, averages the number of RLAN’s geographically and averages the height at which RLANs will be located. This obviously casts a kinder light on use of RLANs and fails to address the extremes; density of RLANs in certain cities, use of RLANs at great height and operation at maximum power of around 4W. Its ex parte concludes that ‘RKF gives the overly optimistic and misguided impression that unlicensed services can successfully coexist with the primary services present in the 6GHz (band)’.

What can I do to protect the 6GHz band?

By signing, you will be endorsing the ex parte opposition letter shown here. Your organization’s name will then be included in a submission to the FCC, made by Aviat Networks.

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Add your name to support the opposition to the proposal. Your name, position and organization will be added to the signatories when this letter is submitted to the FCC.

Protect 6GHz

  

Marlene H. Dortch, Secretary
Federal Communications Commission
445 12th Street, S.W.
Washington, DC 20554

Re: GN Docket No. 17-183, Expanding Flexible Use in Mid-Band Spectrum Between 3.7 and 24 GHz
Ex Parte Communication

Dear Ms. Dortch:
Apple et al. proposes to deploy large numbers of high-powered, uncontrolled unlicensed devices (RLANs) in the 6 GHz microwave bands. We oppose.

We are writing to you express our opposition to the proposals contained in ex parte “Frequency Sharing for Radio Local Area Networks in the 6 GHz Band (January 2018),” prepared by RKF Engineering Services, LLC on behalf of Apple Inc., Broadcom Limited, Cisco Systems, Inc., Facebook Inc., Google LLC, Hewlett-Packard Enterprise, Intel Corporation, Microsoft Corporation, MediaTek Inc., and QUALCOMM Incorporated.

We agree wholeheartedly with the opposition comments made by AT&T and the FWCC (Fixed Wireless Communications Coalition). The 6GHz band is the work horse of the fixed link world in the United States. Its properties are unique in American terms; no other band can support such long links at such high availability. 7GHz and 8GHz are obviously reserved for federal use and 10GHz only supports up to 5MHz channels. The importance of the role of 6GHz, therefore, cannot be overestimated. Further, 6GHz provides critical communications to support both public safety and national infrastructure. AT&T’s ex parte of March 16th points out that the band is home to almost 100,000 microwave links. At a relatively conservative estimate of $125,000 per link for CapEx, $12.5B is invested in the 6GHz band. The value of the work completed by these links on a daily basis, over a matter of years, is more difficult to estimate but likely goes well beyond the value of the hardware installed, especially given the number of public safety and utility deployments in this band.

The FWCC study filed on March 13th, 2018, discredited the study by RKF Engineering by showing its claimed results do not follow from its assumptions, and showed in detail that the RLANs considered by RKF in fact would cause widespread interference. Average distribution of power, population of RLANs and height at which RLANs may be installed is unrealistically kind to any technical analysis of unlicensed services in a carefully coordinated and licensed band. It is our opinion that unlicensed/unregistered RLANs cannot coexist with licensed fixed links and we are greatly concerned that it would be virtually impossible for the FCC to locate any sources of interference in order to provide licensed fixed links with the protection they are entitled to.

Respectfully submitted

Ola Gustafsson, Senior Vice President
AVIAT NETWORKS U.S. INC.
860 N. McCarthy Blvd, Suite 200
Milpitas
CA 95035

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