Rule2023-28006
Unlicensed Use of the 6 GHz Band; and Expanding Flexible Use in Mid-Band Spectrum Between 3.7 and 24 GHz
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
January 8, 2024
Effective
March 8, 2024
Issuing agencies
Federal Communications Commission
Abstract
In this document, the Federal Communications Commission (Commission) builds on the 6 GHz band unlicensed rules by permitting very low power (VLP) devices in the U-NII-5 (5.925-6.425 MHz) and U- NII-7 (6.525-6.875 MHz) portions of the 6 GHz band. The Commission will limit VLP devices to low power levels and subject them to other technical and operational requirements that will permit these devices to operate across the United States while protecting incumbent licensed services that operate in the 6 GHz band from harmful interference. The Commission also takes action in a Memorandum Opinion and Order on Remand that addresses a remand from the United States Court of Appeals for the District of Columbia Circuit concerning an issue raised by television broadcasters. The Commission finds that broadcasters' unsubstantiated claims of interference in the 2.4 GHz band do not warrant any changes to the 6 GHz rules.
Full Text
<html>
<head>
<title>Federal Register, Volume 89 Issue 5 (Monday, January 8, 2024)</title>
</head>
<body><pre>
[Federal Register Volume 89, Number 5 (Monday, January 8, 2024)]
[Rules and Regulations]
[Pages 874-891]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-28006]
=======================================================================
-----------------------------------------------------------------------
FEDERAL COMMUNICATIONS COMMISSION
47 CFR Part 15
[ET Docket No. 18-295 and GN Docket No. 17-183; FCC 23-86; FR ID
190574]
Unlicensed Use of the 6 GHz Band; and Expanding Flexible Use in
Mid-Band Spectrum Between 3.7 and 24 GHz
AGENCY: Federal Communications Commission.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: In this document, the Federal Communications Commission
(Commission) builds on the 6 GHz band unlicensed rules by permitting
very low power (VLP) devices in the U-NII-5 (5.925-6.425 MHz) and U-
NII-7 (6.525-6.875 MHz) portions of the 6 GHz band. The Commission will
limit VLP devices to low power levels and subject them to other
technical and operational requirements that will permit these devices
to operate across the United States while protecting incumbent licensed
services that operate in the 6 GHz band from harmful interference. The
Commission also takes action in a Memorandum Opinion and Order on
Remand that addresses a remand from the United States Court of Appeals
for the District of Columbia Circuit concerning an issue raised by
television broadcasters. The Commission finds that broadcasters'
unsubstantiated claims of interference in the 2.4 GHz
[[Page 875]]
band do not warrant any changes to the 6 GHz rules.
DATES: This final rule is effective March 8, 2024. The Memorandum
Opinion and Order on Remand in the SUPPLEMENTARY INFORMATION is
effective February 7, 2024.
FOR FURTHER INFORMATION CONTACT: Nicholas Oros of the Office of
Engineering and Technology, at <a href="/cdn-cgi/l/email-protection#baf4d3d9d2d5d6dbc994f5c8d5c9fadcd9d994ddd5cc"><span class="__cf_email__" data-cfemail="de90b7bdb6b1b2bfadf091acb1ad9eb8bdbdf0b9b1a8">[email protected]</span></a> or 202-418-0636.
SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Second
Report and Order and Memorandum Opinion and Order on Remand, ET Docket
No. 18-295 and GN Docket No. 17-183; FCC 23-86, adopted on October 19,
2023 and released on November 1, 2023. The full text of this document
is available for public inspection and can be downloaded at: <a href="https://docs.fcc.gov/public/attachments/FCC-23-86A1.pdf">https://docs.fcc.gov/public/attachments/FCC-23-86A1.pdf</a>. Alternative formats
are available for people with disabilities (Braille, large print,
electronic files, audio format) by sending an email to <a href="/cdn-cgi/l/email-protection#672124245257532701040449000811"><span class="__cf_email__" data-cfemail="32747171070206725451511c555d44">[email protected]</span></a>
or calling the Commission's Consumer and Governmental Affairs Bureau at
(202) 418-0530 (voice), (202) 418-0432 (TTY).
Procedural Matters
Regulatory Flexibility Act. The Regulatory Flexibility Act of 1980,
as amended (RFA), requires that an agency prepare a regulatory
flexibility analysis for notice and comment rulemakings, unless the
agency certifies that ``the rule will not, if promulgated, have a
significant economic impact on a substantial number of small
entities.'' Accordingly, we have prepared a Final Regulatory
Flexibility Analysis (FRFA) concerning the possible impact of the rule
changes contained in the Second Report and Order on small entities. The
FRFA is set forth in Appendix C of the FCC document, <a href="https://docs.fcc.gov/public/attachments/FCC-23-86A1.pdf">https://docs.fcc.gov/public/attachments/FCC-23-86A1.pdf</a>.
Paperwork Reduction Act. The Second Report and Order does not
contain new or modified information collection requirements subject to
the Paperwork Reduction Act of 1995 (PRA), Public Law 104-13. In
addition, therefore, it does not contain any new or modified
information collection burden for small business concerns with fewer
than 25 employees, pursuant to the Small Business Paperwork Relief Act
of 2002, Public Law 107-198, see 44 U.S.C. 3506(c)(4).
Congressional Review Act. The Commission has determined, and the
Administrator of the Office of Information and Regulatory Affairs,
Office of Management and Budget, concurs, that this rule is major under
the Congressional Review Act, 5 U.S.C. 804(2). The Commission will send
a copy of the Second Report and Order to Congress and the Government
Accountability office, pursuant to 5 U.S.C. 801(a)(1)(A).
Accessing Materials. People with Disabilities: To request materials
in accessible formats for people with disabilities (braille, large
print, electronic files, audio format), send an email to <a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="75131616404541351316165b121a03">[email protected]</a>
or call the Consumer & Governmental Affairs Bureau at 202-418-0530
(voice), 202-418-0432 (tty).
Synopsis
1. As discussed in greater detail below, the Commission adopts
rules to permit very low power (VLP) devices to operate with up to -5
dBm/MHz effective isotropic radiated power (EIRP) power spectral
density (PSD) and 14 dBm EIRP across the U-NII-5 (5.925-6.425 MHz) and
U-NII-7 (6.525-6.875 MHz) portions of the 6 GHz band. VLP devices will
enable new innovative uses and will provide opportunities to enhance
nascent applications, such as augmented reality/virtual reality, in-car
connectivity, wearable on-body devices, healthcare monitoring, short-
range mobile hotspots, high accuracy location and navigation, and
automation. The rules the Commission is adopting are designed to
support innovation to bring exciting new applications to market while
protecting the important licensed services that operate in the 6 GHz
band from harmful interference. At this time, the Commission is
limiting VLP devices to the U-NII-5 and U-NII-7 bands because the
technical record has mainly focused on the potential for interference
to fixed microwave links which are the predominate uses of these
portions of the 6 GHz band. The Commission plans on proposing to expand
VLP device operation to the U-NII-6 and U-NII-8 portions of the band
which support mobile operations.
A. VLP Power Levels and Protection of the Fixed Microwave Services
2. In making this decision to enable this new class of VLP
unlicensed devices to operate in the 6 GHz band while protecting
licensed incumbent operations from harmful interference, the Commission
notes that this policy represents a careful balancing between enabling
new services and protecting existing services. In response to comments
reflecting incumbents' concerns regarding the potential for harmful
interference as well as analysis in the record, the Commission is
taking reasonable actions to minimize such potential. The Commission
emphasizes the core principle from its Policy Statement (FCC 23-27,
Apr. 21, 2023) that expresses the notion that data-driven approaches
are necessary to promote co-existence. And while the Policy Statement
generally addresses adjacent channel issues, it notes that many of the
technical and policy principles articulated could be applied to co-
channel spectrum sharing as well, such as the sharing scenarios in the
6 GHz band. The Commission's decision herein is consistent with its
principles. In adopting rules to enable VLP devices to share the 6 GHz
band, the Commission has followed this approach in anchoring its
decision on an extensive technical record. The Commission recognizes
the highly variable nature of the electromagnetic environment and
relies on analyses that use a probabilistic approach to evaluating
interference risk rather than basing our decision on worst-case
examples.
3. In considering the maximum power level for VLP devices, the
Commission's goal is to balance competing factors. The Commission aims
to permit as much power as possible for these devices so that the
maximum benefit can be derived from their operation while minimizing
the potential risk of harmful interference to licensed incumbent
operations. As described below, the record is replete with many
analyses and tests that come to widely different conclusions. These
analyses and tests provide a basis for the Commission's understanding
of the potential for VLP devices to cause harmful interference under a
variety of conditions. As described in detail, the Commission believes
based on the technical record that it can permit at this time VLP
devices to operate at up to -5 dBm/MHz power spectral density (PSD) and
14 dBm EIRP without presenting a significant risk of harmful
interference to the licensed microwave incumbents that share the 6 GHz
band.
1. Computer Simulations/Monte Carlo Analysis
4. In considering the technical record, the Commission finds that
two computer simulations based on Monte Carlo analysis submitted by
Apple, Broadcom, et al. and by Apple provide sufficient support for
permitting VLP operation at up to -5 dBm/MHz EIRP power spectral
density (PSD) and 14 dBm EIRP across the U-NII-5 and U-NII-7 portions
of the 6 GHz band. Relying on computer simulations is in harmony with
the Commission's Policy Statement's directive to follow a data-driven
approach to spectrum
[[Page 876]]
management rather than placing dispositive weight on worst-case
examples that may be rare or never occur in practice. In relying on
these computer simulations, the Commission follows the path of its
previous decision in adopting rules for unlicensed 6 GHz low-power
indoor (LPI) devices. For the LPI rules, the Commission characterized a
computer simulation submitted by CableLabs as ``the best evidence in
the record of the impact that unlicensed low-power indoor devices will
have on incumbent operations.''
5. A well-designed computer simulation can simultaneously model
many probabilistic factors that determine whether harmful interference
may occur. These factors include VLP device location variability in
relation to the microwave receiver, height of the VLP device, whether
the VLP device is operating co-channel, the VLP power level, and the
radio propagation environment. In examining the potential for harmful
interference to occur to microwave links from VLP devices, the
characteristics of the microwave links must also be considered.
Microwave links use highly directional antennas typically located on
tall towers or building rooftops to transmit over distances up to 30
kilometers. Because of the heights of these antennas and their
directional nature, VLP devices only present a harmful interference
risk if they are located within the main beam of the antenna and are
close enough to the microwave receiver that a strong signal can be
received. One important factor to consider when modeling interference
to 6 GHz microwave receivers is atmospheric multipath fading.
Atmospheric multipath fading is caused when stable air masses, such as
warm and humid air, lead to stratification of the atmosphere.
Atmospheric multipath fades can be very deep--30 dB or more. However,
deep fades are rare while more mild fades occur more frequently. For a
typical link, fades greater than 30 dB occur, on average, 15 seconds a
month while fades greater than 10 dB occur, on average, 37 minutes a
month. Because of this fading phenomenon, 6 GHz microwave links are
designed with large ``fade margins'' that are typically 25-40 dB. This
fade margin provides transmitted power beyond what is needed to
maintain the link when no fading is occurring. Thus, the typical
microwave link can operate with 5-nines availability (99.999%) despite
the presence of fading. Because the links are designed with these large
fade margins, even when a VLP device is located directly within the
main beam of a microwave antenna at a close enough distance where it
might be possible for it to cause harmful interference, the microwave
link's operation will not be degraded unless a deep enough fade occurs
so that the combination of received signal from the VLP device and fade
depth is greater than the link's fade margin. Thus, VLP operation
during the more frequent mild fades that occur which only consume a
small portion of the fade margin will present only an insignificant
harmful interference risk. An examination of the interference potential
of VLP devices to microwave links must consider not only the position
and transmit power of the VLP devices and the technical characteristics
of the microwave links, but also include the effects of fading.
6. A computer simulation submitted by Apple, Broadcom, et al.
modeled the effect of VLP devices on two hundred forty-seven (247)
fixed microwave links in the San Francisco area. Data from the
Commission's licensing database was used to model each microwave link.
For each iteration during this simulation, 1,146 VLP devices were
randomly placed in the San Fransisco area where the distribution of
devices was determined by the population data--i.e., it was more likely
that the devices were placed in areas with higher population density.
The San Francisco computer simulation indicates that for VLP devices
transmitting at -5 dBm/MHz EIRP PSD the probability of the interference
to noise power (I/N) ratio exceeding -6 dB was 0.003% and the
probability of the I/N exceeding 0 dB was 0.001% over the one million
simulation iterations. The simulation specifies that the same
probability of exceeding -6 dB I/N results when the VLP PSD is 1 dBm/
MHz EIRP, but is correspondingly lower for -8 dBm/MHz and -18 dBm/MHz
EIRP PSD levels and higher for the simulations that used 10 dBm/MHz
EIRP.
7. In addition to providing statistics on the I/N ratio, the
simulation also evaluated the likelihood that the microwave link's fade
margin will be exceeded by the combination of the interference power
received from the VLP devices and the atmospheric multipath fading. For
each of the 247 microwave links in the San Francisco area, the
simulation calculated the fade margin by calculating the actual
carrier-to-noise (C/N) ratio for the microwave link based on the link's
technical parameters and subtracting the C/N ratio needed for the link
to operate at the highest data rate listed in the Commission's database
for that link. The simulation then determined the probability
distribution for the atmospheric multipath fading for each link using
the ITU-R P.530-17 model. The simulation then calculated a distribution
of the noise floor increase for each link based on the I/N statistics
and convolved that with the multipath fading distribution. For VLP
devices operating at powers up to 1 dBm/MHz EIRP, the results indicate
that the probability of the fade margin being exceeded by the
combination of the interference power received from VLP devices plus
the multipath fading is not materially different than the probability
of the link margin being exceeded solely from multipath fading.
According to the simulation results, of the 247 links assessed in the
study, the presence of VLP devices transmitting at 1 dBm/MHz EIRP at
the ``worst-case'' location for a microwave link would change the
probability that the worst-case link will be degraded by 0.3%.
8. The computer simulation submitted by Apple has many similarities
to the San Francisco simulation. Apple's simulation modeled VLP to
microwave receiver interactions in the Houston, Texas area by modeling
a single microwave link while varying the VLP parameters for each
simulation run based on the characteristics of microwave links that
area. Two hundred twenty-four (224) VLP devices operating at 14 dBm
EIRP within bandwidths varying from 20 megahertz to 320 megahertz were
randomly placed within 23.49 kilometers of the microwave link on each
of 10 million iterations.
9. The Houston simulation found that for VLP devices operating at -
5 dBm/MHz EIRP PSD, the -6 dB I/N level was exceeded approximately
0.06% of the time and 0 dB I/N was exceeded approximately 0.01% of the
time. For VLP devices operating at 1 dBm/MHz EIRP PSD, the -6 dB I/N
level was exceeded approximately 0.085% of the time and 0 dB I/N was
exceeded approximately 0.02% of the time. Similar to the San Francisco
simulation, the Houston simulation also examined the likelihood that
the microwave link's fade margin will be exceeded by the combination of
the interference power received from the VLP devices and the
atmospheric multipath fading. These results, which were derived for
various microwave transmitter heights, show that the presence of VLP
devices have no noticeable impact on microwave link reliability
compared to atmospheric multipath fading alone. The simulation for the
Houston area also indicated that the chance of exceeding -6 dB I/N
increased from 0.07% to 0.135% when both VLP and LPI devices were
included as compared to just having LPI present. Finally, this
simulation also
[[Page 877]]
examined the sensitivity of various inputs to the overall result. Apple
claims that the results are sensitive to fixed service receiver antenna
height, where higher microwave receiver antenna height above ground
level results in a lower potential for impact to the microwave link and
that the 35 meter antenna height assumed for the simulation represents
a conservative value because such a height is significantly lower than
the typical microwave receiver height in the Houston area. Likewise,
Apple asserts that the assumed 44 dBi microwave receiver antenna gain
and assumed ITU-R F.1245 antenna pattern do not represent typical
antenna gains or antenna gain patterns and that more realistic inputs
would result in the results showing a lower potential for exceeding -6
dB I/N.
10. AT&T argues that the approximate 0.1% chance that the Houston
simulation indicates for the I/N to exceed -6 dB for a VLP device
operating at 1 dBm/MHz EIRP PSD implies that 1,300 device deployments
in the Houston area would impair the fade margin of a microwave link by
more than 1 dB (i.e., produce an I/N greater than -6 dB) at any given
moment. This contention is based on several misunderstandings of the
Houston Monte Carlo simulation. The approximately 0.1% chance of the I/
N being greater than -6 dB means that on 10,000 of these 10 million
iterations of the simulation, the calculated I/N at the microwave
receiver from all 224 VLP devices was greater than -6 dB; the I/N
contribution from any individual VLP device would be much less. As to
AT&T's contention that this demonstrates a significant risk to the
microwave links, this represents the likelihood that the aggregate
signal from all 224 transmitting VLP devices causes the microwave link
to receive a signal at greater than -6 dB I/N, which represents a 1 dB
reduction in the fade margin of the link. The Commission reiterates
that in the 6 GHz Order, 85 FR 31390 (May 26, 2020), the Commission
stated that it was not making a determination that a signal received at
greater than -6 dB I/N would constitute ``harmful interference.''
11. These simulations examined the statistical relationship that
the combination of the interference power received from VLP devices and
atmospheric multipath fading could have on microwave receivers. Both
the San Francisco analysis and the Houston analysis considered the
summation of microwave receiver noise floor from VLP device
transmissions and the occurrence of atmospheric multipath fading.
Because atmospheric multipath fading and the signal levels received
from the VLP devices are independent phenomenon, in accordance with a
well-known statistical theorem the probability distribution of the
combination of these two processes is the convolution of the
probability distribution of each of the individual processes. The
computer simulations used this mathematical convolution process to
examine the combination of these two processes and illustrate that the
presence of VLP devices does not result in a significant increase in
the likelihood that the fade margin of the links will be exceeded by
the combination of both atmospheric multipath fading and signals
received from the VLP devices. Because the functioning of a microwave
link is only interrupted when the combination of multipath fading and
received VLP signals exceeds the fade margin, these results show that
the presence of VLP devices will not significantly increase the
potential for harmful interference to a microwave link over effects due
to atmospheric fading alone.
12. AT&T claims the data on fade margin exceedance from the
combination of atmospheric multipath fading and VLP devices that the
San Francisco Monte Carlo simulation presents is suspect. The
Commission believes that Apple, Broadcom, et al. have sufficiently
explained how they calculate this data. As they explain, for each link,
the available C/N ratio was calculated based on the link's transmitted
power, propagation distance, receiver antenna gain, receiver feeder
loss, and receiver noise figure and the required C/N ratio was
calculated based on the highest order modulation for the link as
indicated in the Commission's licensing data. The fade margin is simply
the difference between these two C/N ratios. The probability that the
fade margin for a link will be exceeded by an atmospheric multipath
fade was obtained from ITU-R P.530-17. As to whether some of the link
availabilities are excessively low or high, as AT&T claims, the
Commission does not find the range of link availabilities indicated by
the San Francisco simulation to be unrealistic. As Apple, Broadcom, and
Meta indicate, there are many factors that impact the calculated
availability of the microwave links. AT&T also suggests that it would
be useful for the San Francisco simulation to have listed the links
that appear to be more susceptible to VLP interference to help
understand what they have in common. Because none of the links appear
to have an increased potential for the fade margin being exceeded by
the combination of multipath fading and VLP devices operating at the -5
dBm/MHz power level, the information is not necessary to reach a
conclusion regarding the potential for harmful interference occurring.
13. For the Commission to have confidence in the results of
computer simulations, the assumptions and models that are used must be
appropriate. The Commission finds that for both the San Francisco and
Houston simulations, the assumptions are not only appropriate, but also
represent reasonably conservative estimates of the potential impact on
microwave receivers and that using more realistic input assumptions
would produce results showing even less potential impact. Nevertheless,
the Monte Carlo analyses results are important as they represent an
upper bound on what could be expected under real-world conditions with
the actual impact likely to be much lower. To reiterate this point, the
Commission discusses these assumptions.
14. Each of the simulations randomly distributed a number of VLP
devices over the study area for each iteration. The Commission finds
that the number of devices placed within the study area for each
simulation iteration appears to be based on realistic assumptions. Both
simulations assume that all simulated VLP devices will operate outdoors
because indoor VLP devices are assumed to not present an interference
risk to microwave links. The Commission agrees; such an assumption is
consistent with its finding in the 6 GHz Order, which adopted rules
permitting LPI devices to operate with 5 dBm/MHz PSD EIRP and up to 30
dBm EIRP; at least 10 dB more than the Commission is permitting for VLP
devices. The San Francisco simulation assumes that for the population
within the study area, 6% of people will be outdoors, and that 25% of
those people will be using VLP devices. Apple, Broadcom, et al.
indicate that 6% is a realistic assumption because EPA and Department
of Transportation statistics show that the average American spends 90%
of the time indoors and, of the remaining 10%, 4% of the time is spent
in vehicles, which leaves 6% with no attenuation of the signal from
buildings or vehicles. As this assumption is based on Department of
Transportation and Environmental Protection Agency statistics, the
Commission finds that it is reasonable. The Commission believes that
assuming 25% of people outdoors at any given time will be using a VLP
device is a conservative assumption as
[[Page 878]]
even if 25% of the people are simultaneously using devices, many are
apt to be operating using licensed spectrum and of the devices
operating on an unlicensed basis, they are likely to be spread across
the various bands that support unlicensed devices (e.g., U-NII bands 1-
5). Apple, Broadcom, et al. acknowledge this by further stating that
they assume that 90% of the devices will operate on an unlicensed basis
(rather than using licensed spectrum), that 50% of unlicensed devices
will be capable of using the 6 GHz band, and that of these devices
capable of using the 6 GHz band, 65% will actually be using the 6 GHz
band. These appear to be reasonable assumptions. In addition, they
assume that VLP devices will actively transmit 2% of the time. While
VLP devices are not yet deployed, the Commission finds this assumption
reasonable for analytical purposes. Thus, as the number of VLP devices
placed in each iteration for the San Francisco simulation appears to be
based on reasonable assumptions, the Commission concludes that placing
1,146 devices per iteration was appropriate to model the interference
potential of VLP devices.
15. Apple placed 224 VLP devices during each iteration for its
Houston area analysis. This number was based on a set of assumptions
about VLP device use appear to be reasonable. The analysis places all
224 VLP devices around a single microwave receiver resulting in a
similar device density per microwave receiver for I/N computation as
the 247 microwave receivers simulated in the San Francisco simulation;
noting that the reported I/N for each analysis iteration is an
aggregate of the individual I/Ns calculated for each device in that
iteration. Even with a similar device density, the Commission finds
that the fact that the Houston results show a 20 times increase in the
potential for a VLP device to exceed -6 dB I/N is not cause for concern
regarding an increase in the potential for actual harmful interference.
The I/N probabilities calculated from the Houston analysis results from
a worst-case analysis designed to ensure that any possible microwave
receiver configuration is accounted for while the San Francisco
analysis was predicated on the actual microwave receiver layout and
characteristics from the Universal Licensing System (ULS) for that
market and thus reflects a more real world analysis. Moreover, the
Houston analysis assumed that every VLP device was operating co-channel
with the microwave receiver. This situation is unlikely to occur under
actual operating conditions. Second, the propagation models estimate
clutter losses based on the mean for various statistical categories and
are likely to underestimate these losses, especially in cities where
tall buildings and urban canyons are likely to block signals from
microwave receivers. Third, from a purely mathematical standpoint, it
stands to reason that the more devices that are randomly placed around
a microwave receiver, the greater the likelihood that the signal level
received at the microwave receiver may exceed the interference
protection criterion. However, as the Commission believes that the
number of VLP devices used in each simulation run for Houston was
higher than what would be reasonably expected under actual operating
conditions, the Commission believes that the results similarly
overestimate the actual number of devices that would exceed -6 dB I/N.
And even if the results from the San Francisco and the Houston analyses
represent lower and upper bounds, these percentages are sufficiently
low as to pose an insignificant risk of harmful interference to
microwave links. And fourth, as noted in the 6 GHz Order and herein, -6
dB I/N is an interference protection criterion and exceeding that
metric does not in and of itself represent harmful interference as
microwave links are designed with significant fade margin. Lastly, many
microwave links rely on multiple receive antennas that are physically
separated from one another to provide spatial diversity as a method to
mitigate multipath fading. This will make the receivers even more
resistant to multipath fading meaning that the likelihood that the fade
margin will be exceeded by the combination of fading and VLP
interference is even lower than is indicated by the simulation.
16. AT&T points out that for many VLP device use cases there will
be at least two and maybe more VLP transmitters exchanging data at the
same location. The Commission agrees with AT&T that many VLP device use
cases, such as body worn devices and mobile hotspots, involve
communication between multiple VLP devices. However, only one of these
devices will be transmitting at a time. Furthermore, such usage will
usually involve devices located in close proximity, in many cases on
the same person's body, sharing the same channel through intermittent
transmissions. Thus, these multiple devices can appropriately be
considered a single device within the simulation. Moreover, if multiple
proximate devices communicate over different channels, then only one of
the simulated devices would be co-channel with a given microwave
receiver, negating it from consideration within the simulation.
Therefore, the Commission does not agree with AT&T that it is necessary
for multiple proximate VLP devices communicating with each other to be
specifically modeled by the simulations as such use is implicitly
accounted for.
17. One of the key parameters in computer simulations is the
propagation model used to calculate the signal level received by the
microwave receivers from the VLP devices. The Houston simulation uses
the exact propagation models that the Commission specified for the
automated frequency coordination (AFC) systems that manage access to 6
GHz band spectrum by standard power access points, while the San
Francisco simulation departs slightly from this framework. As the
Commission concluded that these models are appropriate in preventing
harmful interference from standard power devices in this band, the
Commission agrees that these models are appropriate for a computer
simulation for VLP devices. The San Francisco simulation departs from
the Commission's AFC rules. As the difference in the propagation models
used in the San Francisco simulation and the Commission's AFC rules
produces a more conservative result--i.e., overpredict the possibility
of interference--they are not only appropriate for evaluating the
potential for exceeding -6 dB I/N, but also act to overprotect
microwave receivers beyond the limits the Commission deems appropriate
in its rules.
18. Another input modeled within the simulations was attenuation to
account for ``body loss'' due to scattering and absorption from a VLP
device operating on or near a body or other object (e.g., a VLP device
placed on a table). As VLP devices are envisioned to generally be small
form factor body worn type devices or devices used in close proximity
to people, this is an appropriate input for analysis. Body loss is a
random variable and subject to variation due to a multitude of factors,
such as whether a device is body-worn or not, what part of the body it
is worn on, body type, and whether it is in a pocket. Thus, a body loss
value for analytic purposes must reflect not just the body loss itself,
but also the wide range of values possible, the varying behavior of VLP
device users, and the variety of uses for which VLP devices may be
employed. Considering the data placed on the record reflecting widely
[[Page 879]]
varying levels of body loss under different conditions, as well as the
general consensus among studies relied on by other regulators, the
Commission finds that the computer simulations' assumptions that there
would be a mean attenuation of 4 dB for body and/or clutter loss and
that this would follow a gaussian distribution is appropriate. The
Commission believes that this is a reasonable approach as it is in the
range specified by many commenters, is consistent with the measurements
made by Meta, and is consistent with what was used by the International
Telecommunication Union (ITU) and the European Conference of Postal and
Telecommunications Administrations' (CEPT) Electronic Communications
Committee (ECC) for interference analysis. While many commenters put
data on the record purporting to show losses greater than 4 dB, the
Commission notes that this data also shows, in some instances, losses
less than this value.
19. Because VLP devices are anticipated to be worn across a wide
range of positions on the body or placed on a wide range of surfaces,
the Commission believes that use of a gaussian distribution with a 4 dB
mean as used by the computer simulations captures the wide range of use
cases described by VLP proponents and is appropriate for analytical
purposes. Gaussian distributions are commonly used to represent random
processes that vary over a range such as far-field body loss.
Considering that the body loss measurements submitted by Apple,
Broadcom, et al. and Meta have a mean higher than 4 dB and some
measured attenuations were much greater than the then 8 dB maximum of
the truncated distributions used in the simulations, use of these
distribution appears to be a conservative assumption. The Commission
does not find merit in AT&T's criticism of the body loss distribution
used by the simulations as not being justified or being ``abnormally''
truncated to plus/minus one standard deviation. While AT&T implies the
distribution must be ``justified,'' it does not provide any information
on what such a justification may entail or how body loss should
otherwise be modeled. Use of a truncated distribution is reasonable as
this prevents the distribution from unrealistically including a body
loss less than 0 dB or incorporating very high body loss values (more
than one standard deviation from the mean) which could be viewed as
outliers and not realistic while maintaining the 4 dB mean.
20. Both computer simulations assumed that 90% of VLP devices would
operate at a 1.5 meter height above ground level. As the simulations
are only modeling outdoor VLP devices, the VLP devices that are at
greater heights will represent use on building balconies and rooftops.
The Commission agrees with Apple, Broadcom, et al. that, assuming that
10% are at heights greater than 1.5 meters appears to be a conservative
assumption. For those 10% of VLP devices that are assumed to be above
1.5 meters, both simulations base the height of the device on data for
building heights in the cities they are modeling. The Commission
concludes that this is a reasonable approach to modeling the VLP device
heights.
21. Both simulations used the ITU-R F.1245 antenna pattern to model
microwave receiver antennas. This ITU recommendation provides an
average antenna pattern to be used in interference assessments. AT&T
criticizes the simulations for not using actual antenna patterns for
the antennas specified in the Commission's licensing database and
suggests that if the actual antenna patterns are not used that ``a
better choice would have been to base the antenna pattern on F.699 and
the FCC antenna mask in Part 101.115 as has been agreed within the
WinnForum'' for the AFC specification.
22. Given that the actual antenna model is not specified for many
of the microwave link licensing records in the Commission's ULS
database and the added complexity of obtaining and integrating into the
simulation antenna patterns for microwave links where the antenna
pattern is known, the Commission appreciates why the simulations did
not use actual antenna patterns. In addition, as the Houston simulation
did not model specific microwave links, using a particular actual
antenna pattern would have been completely arbitrary. The Commission
does not believe the Monte Carlo simulations using a different antenna
pattern than the WinnForum AFC specification detracts from the
simulation's accuracy for two reasons. First, because ITU-R F.699 is
based on the peak envelope for the side lobes it will overestimate the
level of interference from signals received in the side lobes because
most actual antennas will have lower side lobe gain. ITU-R F.1245,
which is based on the average side lobe levels for microwave antennas,
appears to be a more appropriate choice given that the purpose of a
Monte Carlo simulation is to determine the typical level of
interference experienced by microwave receivers and that the
simulations are summing the signals received at the microwave antenna
at different arrival angles from multiple VLP devices. Second, the
WinnForum AFC specification appears to use a mask based on Sec.
101.115 of the Commission's rules for the side lobes because this
permits use of different levels of attenuation for different categories
of microwave antennas for angles of arrival outside the main beam of
the antenna. Because the goal of the AFC systems is to protect specific
fixed microwave receivers from harmful interference from standard power
unlicensed devices, trying to more closely match the characteristics of
particular classes of antennas is important for this purpose. In a
Monte Carlo simulation the goal is to obtain overall statistics on the
likelihood of occurrence of harmful interference to all the microwave
links rather than determining exclusion zones around specific microwave
receivers. Hence, trying to match the characteristics of individual
antennas is of less importance. For this purpose, the Commission
believes that use of the ITU-R F.1245 pattern, which represents an
``average'' antenna pattern, is a reasonable alternative to using the
actual antenna patterns or to following the approach used in the
WinnForum AFC specification.
23. AT&T also criticizes the Houston simulation for not using the
actual microwave link data available in the Commission's ULS licensing
database and instead using different antenna heights and either a 44
dBi antenna gain or antenna gains selected from a distribution whose
source was unspecified. While the San Francisco simulation used the
data from the ULS for each individual link, the Houston simulation took
a different, yet also valid, approach in which it simulated both the
range of microwave receiver characteristics (antenna gain, antenna
height, etc.) and VLP parameters over 10 million iterations to
determine the probability of exceeding -6 dB I/N for any potential VLP
to microwave receiver configuration. Contrary to AT&T's assertion, the
parameters the Houston simulation used are based on distributions taken
from the Commission's ULS licensing database for the Houston market and
are based on real-world data representative of the Houston area. By
choosing a microwave antenna height at the 10-percentile and a
microwave antenna gain at the 90-percentile for the Houston market, the
Houston simulation represents a conservative estimate of the potential
for harmful interference to occur to microwave links from VLP devices
in
[[Page 880]]
the Houston area. While the Commission believes the more complex
approach taken by the San Francisco simulation does have some
advantages over the approach taken in the Houston simulation, the
Houston simulation is a reasonable approach for assessing VLP device
operation in the Houston market.
24. The San Francisco simulation used an antenna pattern for all
VLP devices that is based on a model of consumer Wi-Fi devices
developed by the CEPT SE45 working group. The Houston simulation used
an antenna pattern for client devices from the ECC 302 report, which
examined the interference potential of unlicensed 6 GHz devices. AT&T
states that it has ``previously shown that assumptions made in
simulations by [proponents of VLP devices] rely on inaccurate antenna
patterns and illogical assumptions regarding [device] positioning.'' In
making this broad statement, AT&T refers to its previous discussion of
a Monte Carlo simulation for LPI devices conducted by CableLabs. The
Commission does not believe AT&T's concerns have validity for the two
simulations under consideration here. The Commission finds each of
these studies provide independent grounds for its conclusions.
25. Transmit power control is another important parameter that VLP
devices will use and was appropriately included in the analyses. For
transmit power control the San Francisco simulation used a gaussian
distribution with a mean and standard deviation of 3 dB that is
truncated at 0 and 6 dB. The Houston simulation used a gaussian
distribution with 7 discrete steps from 0 to 6 dB for transmit power
control. The Commission believes that transmit power control is likely
to be implemented for most VLP devices, such as body worn devices, to
save battery power. Consequently, modeling the transmit power control
as a random variable in the computer simulations is appropriate. Given
the ITU resolution and ECC regulation requiring an average power
reduction of 3 dB from transmit power control for U-NII-2A and U-NII-2C
devices and that the Commission previously required that U-NII-2A and
U-NII-2C devices have the capability for at least 6 dB transmit power
control, the Commission believes that the distributions used in the San
Francisco and Houston simulations are reasonable approximations for the
amount of transmit power control VLP devices are likely to employ for
VLP devices.
26. The Houston simulation used a noise figure of 5 dB and a feeder
loss of 1.3 dB for the microwave receivers. AT&T claims that the 5 dB
noise figure is ``larger than typical'' and suggests that using 4 dB
for U-NII-5 and 4.5 dB for U-NII-7 microwave receivers, as in
WinnForum's functional requirements document for AFC systems, would be
a better choice. AT&T also claims that a 1.3 dB feeder loss may not be
appropriate for all cases as many microwave radios are mounted directly
to the antenna and have no feeder loss. Apple, Broadcom, and Meta have
indicated that the simulation used 2 dB for waveguide feeder loss and 5
dB for the noise figure. While the Commission agrees with AT&T that the
noise figure numbers from the WinnForum AFC specification would have
been a better choice than the 5 dB that both simulations used, this up
to 1 decibel difference is not significant enough to make an
appreciable difference in the simulation results. For feeder loss, when
no feeder loss is available in the Commission's ULS database and the
type of microwave radio is known, WinnForum's AFC specification
document indicates that a value of 3 dB be used for radios that are
identified as indoor units while no feeder loss should be used for
outdoor units. Hence, according to WinnForum's AFC specification, a 1.3
dB or 2 dB feeder loss would be too large for an outdoor radio and too
small for indoor radio. As these simulations are designed to model the
potential for harmful interference to occur to microwave links in
general rather than explore the interference risk of a particular
microwave receiver, the Commission believes that employing such an
``in-between'' value for feeder loss is a reasonable approach for a
Monte Carlo simulation.
27. In sum, the Commission's review of Apple, Broadcom, et al.'s
San Francisco Monte Carlo simulation examining the potential for VLP
device interaction with microwave links and the similar Apple
simulation for Houston provide a solid basis for concluding that VLP
devices can coexist with incumbent services in the 6 GHz band with an
insignificant potential for causing harmful interference. In fact, as
noted, the Commission believes that the assumptions and thus, the
results, err on the side of caution, are conservative, and overestimate
the potential for any given VLP device to exceed -6 dB I/N. The worst-
case operating scenario occurs when the VLP device is in the main beam
of a microwave receiver, at close distance, operating co-channel to the
microwave receiver, and not significantly attenuated by terrain, body
loss, or blocked by buildings, which is an event that the simulations
show will be a rare occurrence.
2. Power Level for VLP Devices
28. The computer simulations show virtually no impact on the
microwave links even for VLP devices operating at 1 dBm/MHz EIRP PSD--
the Houston and San Francisco simulations indicate that a -6 dB I/N
event occurs only at either 0.06% or 0.003% of the time, respectively.
The San Francisco results show an identical outcome for VLP devices
transmitting at -5 dBm/MHz PSD and for the Houston simulations, a
slight decrease in occurrences that -6 dB I/N may be exceeded. Thus, as
a conservative initial approach for permitting VLP devices to operate
in the U-NII-5 and U-NII-7 portions of the 6 GHz band, the Commission
will limit them to a maximum of -5 dBm/MHz PSD EIRP and 14 dBm EIRP at
this time. The Commission believes the conservative nature of the
analyses resulting in extremely low probabilities for exceeding -6 dB
I/N justify this approach which balances the need to provide enough
power for VLP devices to ensure manufacturers can provide useful
devices with the requirement to protect licensed incumbent operations
from harmful interference. This approach recognizes, as pointed out by
licensed incumbents, that there are locations where VLP devices
operating at these power levels could result in a signal with I/N
ratios that may exceed -6 dB I/N. However, Apple, Broadcom, et al. and
Broadcom argue that the risk of exceeding that interference protection
criterion is low at even higher power levels. Therefore, the Commission
believes that it is appropriate to be conservative at this time and
permit the VLP devices to operate at no more than -5 dBm/MHz EIRP PSD.
The Commission also limits total EIRP to no more than 14 dBm consistent
with Apple, Broadcom, et al. and other VLP proponents' comments. While
there may be some worst-case locations where harmful interference is
possible, the Commission finds the overall risk insignificant. In
addition, because (i) the Commission is concluding that VLP devices can
operate at -5 dBm/MHz EIRP PSD with an insignificant potential of
causing harmful interference to incumbent operations, and (ii) VLP
devices are inherently mobile, communications between two VLP devices
present no more harmful interference risk than a VLP device
communicating with an access point. Thus, the Commission will permit
VLP devices operating at this PSD level to directly communicate with
each other. The Commission is examining additional steps that it could
take to provide additional power or operating
[[Page 881]]
flexibility to VLP devices. However, given that no VLP devices have yet
to be deployed, the Commission believes limiting operation to no more
than -5 dBm/MHz EIRP PSD is appropriate at this time. Given the
conservative PSD limit the Commission is adopting, we are confident
that the harmful interference risk is insignificant.
29. Southern Company cautions that to the extent the Commission is
relying on computer simulations to inform its decisions for the 6 GHz
band, it should require the underlying algorithms used by the
simulation to be disclosed to all stakeholders consistent with the
Commission's Policy Statement on spectrum management. The Utilities
Telecom Council (UTC) et al. express similar views, arguing that 6 GHz
band unlicensed use proponents relied on simulation information that is
not reproducible by any party and that others have not been given the
opportunity to review or fully understand the data and simulation
methodology. In addition to echoing these views, AT&T suggests that the
Commission should require the simulation code to be released consistent
with the Commission's Policy Statement and the practices of NTIA, which
released similar software for evaluation of 3.1 GHz network
deployments. Both AT&T and Southern Company also criticize the
Commission for not conducting its own computer simulations and instead
relying on those submitted by interested parties.
30. While Apple, Broadcom, et al. and Apple have not made their
simulation code or the resulting raw data produced by the simulations
publicly available, the Commission believes that they have provided
sufficient information for knowledgeable engineers to understand the
algorithms and models used in the simulations. Both Apple, Broadcom, et
al. for the San Francisco simulation and Apple for the Houston
simulation provided filings detailing the significant simulation
assumptions. Apple has indicated that its simulation was prepared using
the widely available and well understood Spectrum Engineering Advanced
Monte Carlo Analysis Tool (SEAMCAT) simulation tool, while Apple,
Broadcom, et al. indicated that its simulation was implemented using
the C++ programming language using well-established Monte Carlo
simulation techniques. Through these filings to the record, the
Commission believes that Apple, Broadcom, et al. and Apple have
provided enough technical details that engineers experienced in radio
propagation modeling and coexistence analysis would be able to conduct
identical simulations and obtain consistent results. Furthermore, the
Commission observes that it is noteworthy that no opponents of VLP
deployment have conducted their own simulations to confirm or refute
the results. The Commission has no statutory obligation to conduct or
commission [its] own empirical or statistical studies. The Commission
therefore concludes that the results presented in the filings are
adequate to inform its decision. The Commission's decision to authorize
VLP devices will encourage innovative methods of using the 6 GHz band
and the Commission is exercising its technical judgment in relying on
the simulations from Apple, Broadcom, et al. and Apple in reaching this
decision. The Commission notes that parties opposing its low-power
indoor (LPI) rules raised a similar concern in a challenge to the
previously adopted 6 GHz unlicensed rules in the United States Court of
Appeals for the District of Columbia Circuit regarding a computer
simulation conducted by CableLabs on which the Commission relied. The
court rejected that challenge noting that ``requiring agencies to
obtain and publicize the data underlying all studies on which they rely
would be impractical and unnecessary.'' In accordance with this
established precedent, the Commission finds that Apple, Broadcom, et
al. and Apple provided ample information on the record such that any
interested party could undertake similar analyses and that opponents'
challenge on this point is meritless.
31. Fade margin infringement. The Fixed Wireless Communications
Coalition (FWCC) expresses a strong opinion that unlicensed devices
should not be permitted to infringe on the fade margin of microwave
links. FWCC claims that it has ``shown that interference from
unlicensed (RLAN) operations will cut into the fade margin and leave FS
systems vulnerable to data loss and outages.'' FWCC claims that because
adding fade margin is expensive, system designers build only the
necessary minimum, with a small safety margin, and that any unlicensed
interference that encroaches into a microwave link's fade margin will
reduce the link reliability.
32. As the Commission stated in the 6 GHz Order which authorized
LPI devices, it ``is not required to refrain from authorizing services
or unlicensed operations whenever there is any possibility of harmful
interference.'' Instead, ``the Commission may authorize operations in a
manner that reduces the possibility of harmful interference to the
minimum that the public interest requires, and it will then authorize
the service or unlicensed use to the extent that such authorization is
otherwise in the public interest.'' There is no prohibition in either
previous Commission decisions or legal precedents on the Commission
adopting rules that permit VLP devices to occasionally infringe upon
the fade margins of microwave links. Instead, the Commission's
responsibility is to ensure that the operation of the VLP devices might
only impose an insignificant risk of harmful interference occurring to
the microwave links to the minimum that the public interest requires.
The Commission believes based on the computer simulations, which take
into account both the technical characteristics of actual microwave
links and reasonable technical assumptions for VLP devices, that the
Commission's decision is within the bounds of this principle.
Furthermore, noting that the 6 GHz band is populated by both microwave
licensees representing commercial and public safety interests, the
Commission observes that there is no appreciable difference between the
systems operated by those different entities and finds that the rules
we are adopting protects both commercial and public safety microwave
systems in a comparable manner. Finally, the Commission reiterates that
in its recent Policy Statement, the Commission noted that ``zero risk
of occasional service degradation or interruption cannot be
guaranteed'' whether from natural events or other spectrum users.
3. Fixed Infrastructure Prohibition
33. As suggested by Apple, Broadcom, Google, and Meta, the
Commission is prohibiting VLP devices from operating as part of a fixed
outdoor infrastructure. The Commission notes that no commenters have
opposed us adopting this prohibition. This measure is being adopted as
an additional means of protecting incumbent operations to ensure that
all VLP devices are subject to body and/or clutter loss, to add
additional assurance that the simulation assumption that most outdoor
devices will operate at 1.5 m above ground level is correct, and to
force all devices to be itinerant consistent with the VLP devices
simulated in the Monte Carlo analyses. Thus, VLP devices will be
prohibited from attaching to outdoor infrastructure, such as poles or
buildings, that would make any instances of potential interference more
than fleeting. In addition, device mobility results in devices, even if
remaining in a general location, constantly changing their orientation
due to even subtle body movements.
[[Page 882]]
Such movements can result in widely varying VLP signal levels in any
given direction. Thus, the maximum VLP signal level, which is likely to
be less than the maximum the Commission's rules permit for a device in
the worst-case location and operating co-channel to a microwave system,
may only be oriented toward a microwave receiver for a short period of
time, which also serves to keep the potential for causing harmful
interference to a minimum.
4. Transmit Power Control Requirement
34. The Commission is adopting a requirement that VLP devices
employ a transmit power control mechanism that has the capability to
operate at least 6 dB below the -5 dBm/MHz EIRP PSD level permitted for
VLP devices. Both computer simulations, which the Commission have
concluded is the best evidence that the potential for VLP devices to
cause harmful interference is insignificant, assume that VLP devices
would operate with a transmit power control mechanism with a range up
to 6 dB and a mean power reduction of 3 dB. To ensure that actual VLP
devices operate consistent with the simulations on which its relying,
the Commission adopts this provision to provide confidence that such
devices do indeed operate using transmit power control. The Commission
is not placing any specific requirements in its rules as to how the VLP
device transmit power control algorithm will function, but proof of
such functionality must be provided with a device's application for
equipment certification. The Commission does not expect that placing
this transmit power control requirement will present an undue burden on
device manufacturers as such functionality is routinely included in
battery-powered device design to conserve battery power. In this
connection, Broadcom states that transmit power control is enabled in
100% of its portable products. In addition, Apple, Broadcom, Google,
and Meta jointly suggested that the Commission adopt a VLP device
transmit power control requirement that would require such devices to
reduce their PSD by 3 dB on average. No commenters have opposed us
mandating that VLP devices employ a transmit power control mechanism.
While AT&T advocates that any limitation on VLP device use that was
assumed in the computer simulations, such as average power due to
transmit power control, should be subject to a specific rule, the
Commission notes that it's adopting a rule requiring VLP devices to
have transmit power control capability to reduce power by at least 6
dB. While the exact power distribution that VLP devices will use is
unknown at this time, the Commission believes this requirement is
reasonable given the diversity in propagation environments in which VLP
will operate.
5. Equipment Compliance and Enforcement Matters
35. Consistent with the requirements for most other unlicensed
transmitters, the Commission requires 6 GHz VLP transmitters to be
approved under the Commission's certification procedure. This procedure
requires that the equipment be tested by an accredited laboratory and
approved by a designated Telecommunication Certification Body (TCB) to
ensure that the equipment complies with all requirements that the
Commission is adopting, e.g., maximum power (EIRP and PSD), transmit
power control, contention based protocol, which are designed to ensure
that the risk of harmful interference to licensed incumbent services is
insignificant. As a general matter, only 6 GHz VLP devices certified as
compliant by a TCB will be permitted to be imported into and marketed
and operated within the United States.
36. For reasons discussed throughout the Report and Order, the
Commission is confident that the risk of harmful interference to
licensed incumbent services is insignificant, based on the VLP
technical rules adopted herein and on the compliance measures in place
under the its equipment authorization rules. The Commission also
emphasizes that 6 GHz VLP devices, like other part 15 devices, are not
permitted to cause harmful interference and that any such interference
is actionable for enforcement purposes. Section 15.5(b) of the
Commission's rules provides that ``[o]peration of an intentional,
unintentional, or incidental radiator is subject to the condition[ ]
that no harmful interference is caused.'' In the unlikely event that
harmful interference does occur due to VLP operations, Sec. 15.5(c) of
the Commission's rules provides that ``[t]he operator of a radio
frequency device shall be required to cease operating the device upon
notification by a Commission representative that the device is causing
harmful interference,'' even if the device in use was properly
certified and configured, and that ``[o]peration shall not resume until
the condition causing the harmful interference has been corrected.''
Although UTC asks the Commission to ``propose processes and procedures
for the identification, reporting and resolution of interference from
unlicensed operations as part of [future rulemaking],'' the Commission
already have processes and procedures in place under which the
Enforcement Bureau investigates complaints of harmful interference and
takes appropriate enforcement action, as necessary. These processes and
procedures have been effective in identifying and resolving harmful
interference to licensed operations in other situations and are
available for use in the 6 GHz band as well.
37. Parties that believe particular 6 GHz VLP devices are not
compliant with the Commission's rules or are causing harmful
interference to licensed incumbent services can contact the Enforcement
Bureau, which will address any rule violations, such as impermissible
operations or marketing of non-compliant devices, as appropriate.
6. Cumulative Effect of Different Classes of Unlicensed Devices
38. AT&T contends that 6 GHz unlicensed devices have been modeled
under the erroneous presumption that each type of device--standard
power, LPI, and VLP--can interfere with microwave links up to a
threshold of -6 dB I/N, but as there is only one -6 dB I/N margin, the
modeling must account for consumption of that margin by all three types
of devices. AT&T points out that no computer simulation models the
combined impact of all these different types of unlicensed devices.
AT&T points to the CEPT computer simulation that addressed 6 GHz
devices that did not include standard power devices, simulated LPI
devices at a lower power level than the Commission's rules permit, and
only assumed 1% of devices located outdoors as illustrating the error
in the VLP proponents reasoning.
39. As the Commission stated above, typical microwave link
architecture results in 6 GHz band unlicensed devices only presenting a
potential interference risk if they are in the microwave antenna's main
beam at a close enough distance that a signal of sufficient strength
will be received. The AFC systems that control standard power access
points' spectrum access will prevent those devices from operating at
locations where they present a risk of causing harmful interference.
Therefore, the Commission does not believe that it is necessary for
unlicensed proponents to provide a study that jointly considers the
potential for harmful interference from the cumulative effect of
standard power devices and other types of unlicensed 6 GHz devices.
Regarding VLP and LPI devices, the Commission again points out that
Apple's Monte Carlo analysis
[[Page 883]]
for devices operating in the Houston areas included results for the
additive effect of LPI and VLP devices and concluded that the
likelihood that there was no material effect on potential microwave
degradation due to the presence of both the LPI and VLP devices.
7. Request for Higher Power
40. While supporting comments advocating for a 14 dBm EIRP power
level, a subset of VLP device advocates point out that allowing even
higher power would enable VLP devices to communicate with higher order
modulation, which would enable higher throughputs and lower latencies
and request that the Commission authorize up to 21 dBm EIRP. They claim
that the 14 dBm EIRP power level would be insufficient for untethered
augmented reality/virtual reality, remote surgery, data center wireless
flyways, educational applications requiring transmitting high
resolution materials, and other demanding applications. They point to
the computer simulation conducted by RKF to claim that operation at
this power level would not cause harmful interference to licensed
stations.
41. As these commenters also support the more modest 14 dBm EIRP
power level and the applications cited are more speculative than those
generally cited as other use cases for VLP devices, the Commission
declines to permit additional power for VLP devices at this time. The
Commission also observes that devices delivering many of the cited
applications, such as remote surgery, necessitate indoor operation and
can be conducted under the LPI device rules that already permit more
power than the Commission is permitting for VLP devices. Much of the
Commission's decision is based on the computer simulations that are
based on a maximum 14 dBm EIRP power level. Due to the undeveloped
record on operations with up to aa 21 dBm EIRP, the Commission declines
to permit VLP devices to operate at greater than 14 dBm EIRP. The
Commission does not plan on seeking comment, however, on whether we
can, under certain circumstances, increase the VLP power level without
increasing the harmful interference risk to incumbent operations.
8. Request for Lower Power
42. The Ultra Wide Band (UWB) Alliance expresses concern that VLP
devices will radiate power uniformly in all directions even though they
likely only need the maximum power in a specific direction and that
this will result in unnecessary interference to other receivers,
including other VLP devices. To address this issue, it suggests that
VLP devices meet one of two alternate power limits: (1) a -32 dBm power
spectral density with a peak power of 0 dBm; or (2) a -8 dBm power
spectral density that is reduced by 2 dB for every dB that the antenna
gain is less than 12 dBi as well as a peak power of 14 dBm that is
reduced by 2 dB for every dB that the antenna gain is less than 7 dB.
The UWB Alliance also suggests that dynamic transmit power control be
required for VLP devices as the power needed for on-body locations can
vary from nearly free space to over 70 dB. Other commenters such as
Nokia, the National Association of Broadcasters (NAB), and AT&T suggest
that we only permit VLP if we limit such devices to much lower power
than what the Commission proposed.
43. While several commenters request that the Commission only
permits VLP devices to operate at lower power, for the reasons already
articulated we decline to do so. First, the Commission concludes based
on the computer simulations that VLP device operation at -5 dBm/MHz PSD
will only pose an insignificant risk of harmful interference to
incumbent operations. Additionally, the Commission appreciates the UWB
Alliance's concern for improving spectrum efficiency and reducing the
potential for interference by proposing rules that would incentivize
the use of directional antennas. However, the Commission agrees with
Apple, Broadcom, et al. that directional antennas are likely infeasible
for small form factor portable devices, particularly when the device's
orientation is constantly changing. The Commission does not believe
that it would be appropriate to adopt rules that would likely make it
impractical to manufacture devices for many of the proposed VLP use
cases, such as small portable body-worn devices. As for the UWB
Alliance's suggestion to require dynamic transmit power control, as
explained above, the Commission is adopting such a requirement on VLP
devices. Second, the Commission does not believe that tying the power
level for VLP devices to the power levels for low-power indoor devices,
as NAB and AT&T suggests, is appropriate, given the fundamental
differences between these device classes. VLP devices will inherently
be mobile rather than stationary like LPI access points, have smaller
form factors, less efficient antennas due to the small form factors,
and operate at low power levels to conserve battery. Finally, as the
Commission specified in the 6 GHz Order, ultra-wideband and wideband
devices operate under part 15 unlicensed rules, and providing specific
accommodations would effectively provide those devices with a level of
interference protection to which they are not entitled. Consequently,
the Commission believes that the -5 dBm/MHz PSD EIRP and maximum 14 dBm
EIRP are appropriate and will result in widespread coexistence within
the 6 GHz band among the various devices that operate there. Thus, the
Commission is not persuaded to reduce VLP device utility by
artificially restricting their power levels to even lower levels.
9. VLP Devices and the AFC
44. Many microwave incumbents advocate that VLP devices should be
required to use an AFC system to control spectrum access based on their
potential to cause harmful interference to microwave receivers. As the
Commission concludes that the risk of harmful interference from VLP
devices operating at -5 dBm/MHz is insignificant, the use of AFC
systems to control spectrum access by VLP devices is unnecessary. Thus,
the Commission sees no reason to impose such a requirement on VLP
devices. While there is dispute on the record as to how much it would
cost to impose AFC control on VLP devices, there clearly is some cost
to imposing such a requirement without a requisite benefit.
Furthermore, there will likely be some VLP devices, such as laptop
computers that do not have geolocation capabilities and requiring such
devices to operate under AFC control would limit the utility of the VLP
rules. In addition, neither the standard power or LPI rules support the
highly mobile applications envisioned for VLP devices as LPI devices
are limited to indoor locations utilizing access points that are
supplied power by a wired connection while standard power access points
may not be mobile. The Commission does note that consistent with 6 GHz
low-power indoor unlicensed devices as well as all client devices, the
Commission will require VLP devices to include a contention-based
protocol which will act to avoid channels on which incumbent systems
are actively transmitting.
10. Link Budget Analysis
45. As discussed in more detail below, a number of commenters
submitted link budget analyses that they claim show that harmful
interference will result from VLP device operation. The Commission
disagrees with CTIA--
[[Page 884]]
The Wireless Association (CTIA), Southern Company, and others regarding
the utility of link budget analysis in driving the Commission's
decision regarding VLP devices. In determining whether to permit VLP
devices to operate in the 6 GHz band, the controlling factor is the
potential risk that VLP devices could cause harmful interference to
microwave links. This is a function not just of the received power
level from a VLP device at a ``worst-case'' location, but also of the
likelihood that a device will be at the location at the same time that
a severe enough atmospheric multipath fade occurs to overcome the
microwave link's fade margin. This question is not one that a link
budget analysis alone can answer. A link budget provides a calculation
of the power received at a receiver at one instant of time based on
deterministic quantities for quantities such as transmitted power
level, propagation loss, antenna gain, polarization loss, feeder loss,
etc. Such an analysis does not take into account probabilistic
quantities such as multipath fading or the likelihood of a transmitting
device being in a particular location or transmitting co-channel with a
microwave links. One important factor that a link budget analysis
cannot consider is the fact that, because the Commission is prohibiting
VLP device use for fixed infrastructure purposes, the VLP devices will
be mobile and will not remain in potentially problematic locations for
significant periods of time. A computer simulation that takes into
account the transient nature of VLP use is a better model for
determining VLP device interference potential as compared to a link
budget analysis. The Commission also disagrees with Southern Company's
contention regarding the utility of computer simulations as the number
of VLP devices reach the millions. In fact, that is exactly what Monte
Carlo simulations are designed to analyze, especially when each device
is subject to multiple probabilistic operating conditions. The
assumptions used in the San Francisco simulation to determine the
number of simultaneously transmitting devices in the San Fransisco area
assumed millions of VLP devices present in that area, but that did not
mean that all these devices were transmitting simultaneously co-
channel. As discussed above, that simulation starts with the 13,066,000
people in the San Francisco area and calculates how many VLP devices
will be simultaneously transmitting outdoors in the area based on
assumptions as to how many people are outdoors, how many of these
people use VLP devices, how many VLP devices are capable of using the 6
GHz band, how many VLP devices actually use the 6 GHz band, and how
many VLP devices are actively transmitting at a given moment.
46. As already noted, the Commission believes that Monte Carlo
analysis is the most appropriate method for evaluating the potential
for VLP devices to exceed -6 dB I/N. Although the link budget analyses
provided by commenters conclude that in some instances the I/N caused
by a VLP device could exceed that interference protection criterion,
these analyses suffer from one of the same fundamental flaws as the
AT&T link budget analysis that the Commission rejected in the 6 GHz
Order--that is, they rely on worst-case scenarios that overstate the
potential for harmful interference. For example, Southern Company and
Edison Electric Institute (EEI) submitted link budget analyses which
assumed that all VLP devices are operating in locations within the main
beam of the antenna. Nokia submitted a link budget analysis in which it
similarly assumed that VLP devices were operating either in buildings
directly beneath a microwave receiver and at street level within line-
of-sight to a 6 GHz microwave receiver. Furthermore, all the link
budget analyses relied on inappropriate assumptions for certain values,
such as antenna pattern mismatch, feeder line loss, and propagation
model. Moreover, just the mere possibility that under certain
circumstances and in certain locations an I/N may rise to a level
greater than -6 dB I/N does not translate to any certainty that harmful
interference will occur; several other independent factors must also
simultaneously occur and the probability of those events occurring is
sufficiently low to lead us to the Commission's conclusion that based
on the analyses in the record, VLP devices can coexist with incumbent
operations in the 6 GHz band with an insignificant risk of causing
harmful interference.
11. Interference Studies
47. Several utilities filed field test measurement reports directed
at quantifying LPI device interference potential on actual microwave
receivers. While the focus of those studies is on LPI devices that are
located indoors, some of the results do have implications for
understanding the potential for VLP devices to cause harmful
interference. CTIA and Southern Company jointly conducted field
measurements using a signal generator to emulate both LPI and VLP
devices which they claim show the emulated VLP device reduced the
microwave link fade margin between 5.2 dB and 10.9 dB. For its test,
Evergy used a commercially purchased LPI access point. When the result
is adjusted for the power difference between LPI and VLP devices, the
test indicates the I/N could be 14.5 dB for a VLP device located next
to a window in a school classroom. Other electric utilities also
conducted field test measurements: First Energy reports I/N ratios as
high as 9.1 dB and Southern Company reports I/N ratios at high as 25.7
dB.
48. Apple, Broadcom, et al. criticize these field tests for using
an indirect methodology to measure the reduction in link fade margin
and estimating the I/N ratio. Apple, Broadcom, et al. claim the field
test methodology is unreliable and produces inconsistent results. They
also claim that the test chose worst-case locations and set the LPI
access point parameters to reflect only extreme worst-case scenarios
with unrealistic data rates. In addition, NCTA--The internet &
Television Association (NCTA) suggests that the field test should use a
metric based on the microwave link's signal to interference-plus-noise
ratio S/(I+N) rather than using an I/N ratio or a reduction in fade
margin as an interference metric as the S/(I+N) ratio would take into
account the characteristics of the microwave link.
49. The Commission believes Apple, Broadcom, et al. and NCTA
express valid points about the field test results, especially regarding
the testing methodology. However, as the Commission's focus here is on
the potential for VLP devices to cause harmful interference and the
field tests were mainly directed to LPI devices, the Commission
refrains from opining on how representative the tests are of LPI device
use. As for their connection to assessing VLP interference potential,
the Commission observes that they too rely on worst-case scenarios that
overstate the potential for harmful interference and therefore suffer
from the same flaw as the link budget analyses and as the AT&T study
that was rejected in the 6 GHz Order. The field tests purport to
measure the I/N ratio at a worst-case location directly within the main
beam of a microwave receiver. Furthermore, as these tests do not take
into the account the fade margin designed into the microwave link and
the occurrence of atmospheric multipath fading, they are of limited
utility in determining the likelihood that the microwave links will
actually experience harmful interference from a mobile VLP device,
which by nature is unlikely to remain at any specific location or in a
fixed orientation for a significant interval of time. Thus, these field
tests are not
[[Page 885]]
informative with respect to the impact that VLP devices could have on
microwave link reliability.
12. Chain of Coincidences Rationale
50. AT&T claims that the VLP device proponents make a flawed
argument in claiming that ``a chain of improbable coincidences'' is
necessary for interference to occur to microwave links and ``citing
indoor use, device positioning, channel overlap, body loss, RLAN
antenna gain, transmit power control, fade margin and itinerant use.''
The Commission agrees with AT&T to the extent that it intimates that
merely mentioning each of these factors, claiming each is unlikely, and
thus deducing that harmful interference is unlikely to occur is of
little utility. Consequently, while these assertions may have some
merit, the Commission did not rely on them in reaching our conclusions
here. Instead, the Commission's conclusions rely heavily on the San
Francisco and Houston Monte Carlo simulations, which considered the
respective likelihood for different factors that could impact
interference potential to quantify the overall risk of harmful
interference occurring to 6 GHz microwave links. Based on these
analyses, the Commission concludes that the risk is insignificant.
B. Fixed Satellite Services (FSS)
51. The entire 6 GHz band is allocated for the FSS in the Earth-to-
space direction. Additionally, portions of the U-NII-7 and U-NII-8
bands are allocated for FSS space-to-Earth (downlink) operations.
However, there are no licensed downlink earth stations in the U-NII-7
band. Sirius XM and Globalstar were the only FSS operators to file
comments in response to the Further Notice of Proposed Rulemaking
(FNPRM), 88 FR 43502 (July 10, 2023), but these comments were limited
to their operations in the U-NII-8 band.
52. In 6 GHz Order, the Commission concluded that FSS receivers in
space would not receive harmful interference from either 6 GHz standard
power or LPI devices. Considering that the satellites receiving in the
6 GHz band are limited to geostationary orbits, approximately 35,800
kilometers above the equator, the Commission found that it is unlikely
the relatively low power unlicensed devices would cause harmful
interference to the space station receivers. The only restriction that
the Commission adopted to protect the satellite receivers was to
require that outdoor standard-power access points limit their maximum
EIRP above a 30 degree elevation angle to 21 dBm. Because VLP devices
are limited to no more than 14 dBm EIRP, for the same reasons, the
Commission concludes that no restrictions on VLP devices are necessary
to protect FSS Earth-to-space operations.
C. Radio Astronomy Services
53. Incumbent operations in the U-NII-7 band include several radio
astronomy observatories, located in remote areas, that observe methanol
spectral lines between 6.65-6.6752 GHz. To protect these radio
observatories, the National Academy of Sciences' Committee on Radio
Frequencies (CORF) requests that we implement exclusion zones for this
band, as listed in Allocation Table footnote US385, if VLP devices are
able to determine their locations. If the devices are not able to
determine their locations, CORF claims that the radio observatories
must be protected by notching out the VLP device's transmissions within
this band.
54. When the Commission adopted the rules for 6 GHz LPI devices, it
did not implement exclusion zones or require the LPI devices to notch
out the 6.65-6.6752 GHz band. Because VLP devices will operate at an
even lower power than LPI devices, the Commission does not expect them
to create an interference problem for the radio observatories. The
Commission recognizes the importance of these observations to the
scientific community but, as VLP devices will not operate under the
control of an AFC system and will not be required to have a geolocation
capability, the Commission is not able to adopt exclusion zones around
these radio observatories. The radio observatories that receive in the
6 GHz band are in remote locations, and it is unlikely that unlicensed
VLP devices will be operating nearby. Furthermore, these observatories
can restrict such devices from being used at their facilities.
Consequently, the Commission concludes that radio astronomy operations
will not be subject to harmful interference from unlicensed VLP
devices. Given this conclusion, the Commission cannot justify requiring
VLP devices to notch out this band as requested as this would increase
device complexity and result in less efficient spectrum use.
D. Emission Mask and Out-of-Band Emission Limit
1. Limits for Very Low Power Devices in the U-NII-5 and U-NII-7 Bands
55. In the FNPRM, the Commission sought comment on appropriate
power levels and other technical parameters that VLP unlicensed devices
in the 6 GHz band should have to meet. The Commission notes that there
were no comments regarding the in-band emission mask for 6 GHz VLP
devices. The Commission's previous decision in the 6 GHz Order found
that the emission mask originally proposed by RKF engineering, with
certain modifications, was necessary to protect incumbent microwave
links and other services operating in the adjacent channel to
unlicensed devices within the U-NII-5 through U-NII-8 bands. Because 6
GHz VLP devices will operate in two of these same bands and on the same
channels as LPI and standard power 6 GHz devices and need to protect
the same incumbent operations, the Commission finds that using the same
emission mask for VLP devices as adopted for LPI and standard power
devices is appropriate. As the incumbent operations' protection
requirements have not changed since the Commission's previous decision
for this band, using the same mask ensures that those operations are
fully protected from unlicensed adjacent channel operations. Moreover,
by adopting the same emission requirements, the Commission anticipates
that device manufacturers will be able to take advantage of economies
of scale regarding filters necessary to meet these requirements which
should help to reduce costs. Finally, the Commission takes this
opportunity to again point out that the emission specification it's
adopting represents the minimum requirement. The Commission encourages
device manufacturers, consistent with the recent Commission Policy
Statement, to design their devices to minimize energy transmitted into
adjacent channels.
56. Accordingly, the Commission is requiring emissions from VLP
devices in the U-NII-5 and U-NII-7 bands to comply with the
transmission emission mask adopted in the 6 GHz Order. That is, the
Commission is requiring the power spectral density to be suppressed by
20 dB at one megahertz outside of an unlicensed device's channel edge,
suppressed by 28 dB at one channel bandwidth from an unlicensed
device's channel center, and suppressed by 40 dB at one and one-half
times the channel bandwidth away from an unlicensed device's channel
center. At frequencies between one megahertz outside an unlicensed
device's channel edge and one channel bandwidth from the center of the
channel, the limits must be linearly interpolated between the 20 dB and
28 dB suppression levels. At frequencies between one and one and one-
half times an unlicensed device's
[[Page 886]]
channel bandwidth from the center of the channel, the limits must be
linearly interpolated between the 28 dB and 40 dB suppression levels.
Emissions removed from the channel center by more than one and one-half
times the channel bandwidth, but within the U-NII-5 and U-NII-7 bands,
must be suppressed by at least 40 dB.
2. Emission Limits Outside the U-NII-5 and U-NII-7 Bands
57. The Commission is adopting emissions limits at the edge of the
U-NII-5 and U-NII-8 bands for VLP devices that are identical to the
emissions limits that the Commission adopted in the 6 GHz Order.
Specifically, the Commission is adopting a -27 dBm/MHz EIRP limit for 6
GHz VLP devices at frequencies below the bottom of the U-NII-5 band
(5.925 GHz) and above the upper edge of the U-NII-8 band (7.125 GHz),
but will not require it between the sub-bands, i.e., between the U-NII-
5 and U-NII-6, the U-NII-6 and U-NII-7, and the U-NII-7 and U-NII-8
bands; those emissions are subject to the emission mask and out-of-band
emission (OOBE) limits discussed above. These limits are intended to
protect cellular vehicle-to-everything (C-V2X) operations below the 6
GHz band and Federal operations above the band. The Commission
previously determined that the -27 dBm/MHz limit will sufficiently
protect C-V2X operations from harmful interference from U-NII devices
operating in other bands.
58. The Commission notes here that it adopted rules that require
Intelligent Transportation System (ITS) licensees to cease use of the
5.850-5.895 GHz band and operate only in the 5.895-5.925 GHz band. In
the 5.9 GHz Order, 83 FR 23281 (May 3, 2021), the Commission also
required that dedicated short range communications (DSRC)-based
technology operating in the ITS radio service transition to C-V2X-based
technology. The FNPRM, 86 FR 23323 (May 3, 2021), in that proceeding
addressed transitioning all ITS operations in the revised ITS band at
5.895-5.925 GHz to C-V2X-based technology, including the appropriate
timeline for the implementation and codification of C-V2X technical
parameters for operation in the 5.895-5.925 GHz band. Since then, the
C-V2X proponents requested and the Commission has begun granting
waivers to allow immediate C-V2X deployment in the ITS bands prior to
the initiation of final rules for CV2X operations.
59. Several parties support the -27 dBm/MHz EIRP emission limit,
while other parties make alternative proposals. A group of VLP
proponents jointly propose a compromise out-of-band emission limit that
would apply at the bottom of the U-NII-5 band. Specifically, they
propose that VLP devices comply with a -37 dBm/MHz out-of-band emission
limit at 5925 MHz measured by root mean square (RMS) to ensure
coexistence when 6 GHz devices are operating in the lowermost channels
and that VLP devices prioritize operations in channels above 6105
megahertz.
60. The Commission is not convinced at this time that a more
stringent out-of-band emission limit nor operational restrictions
suggested by C-V2X proponents are necessary to protect in-vehicle C-V2X
devices from harmful interference. The Commission already determined
that standard power and LPI 6 GHz devices must comply with this same -
27 dBm/MHz out-of-band emission limit and that emissions at or under
that limit will protect adjacent band users from harmful interference.
C-V2X devices must be designed to successfully operate in an
interference-limited environment as they are subjected to co-channel
and adjacent channel signals between each other that are higher than
the -27 dBm/MHz out-of-band emission limit the Commission is adopting
here for 6 GHz unlicensed VLP devices. C-V2X devices have to coexist
with other C-V2X devices that operate in close proximity to each other,
e.g., other on-board units (within vehicles) and roadside units.
Finally, to the extent that commenters raised concerns about harmful
interference from aggregate VLP device emissions, the Commission notes
that the number of such devices present in any given vehicle is
anticipated to be low and because transmissions between VLP devices
would occur over very short distances, the transmit power levels and
their associated out-of-band emissions are expected to be well below
the maximum permitted. Thus, even if multiple out-of-band emissions
were aggregated, the total out-of-band emissions in the local area
would still be expected to be below C-V2X device's own signal levels.
The Commission also believes that maintaining the -27 dBm/MHz emission
limit is appropriate in part because the rules for C-V2X operation in
the 5.895-5.925 GHz band are the subject of a pending rulemaking
proceeding and current C-V2X operations are pursuant to conditional
rule waivers.
61. The Commission declines to adopt the -37 dBm/MHz out-of-band
emissions limit suggested by some parties. However, the Commission
plans on seeking additional information on the potential impact that
VLP devices operating in motor vehicles could have on C-V2X performance
and whether any modification of the out-of-band emission limit or other
technical or operational requirements are appropriate. Likewise, the
Commission finds the -60 dBm/MHz out-of-band emission limit suggested
by the Alliance for Automotive Innovation (AAI) for application at the
U-NII-5 band edge to be too restrictive. In addition, the Commission
finds AAI's suggestion to require VLP devices to operate with a 1-2%
duty cycle that is averaged over a range of tens of milliseconds is not
reasonable. While duty cycle is an important parameter for system
operation, the Commission typically does not make rules requiring
adherence to specific duty cycle requirements as they may artificially
restrict design choices and limit the applications that can be used by
the American public. Similarly, the Commission declines to adopt a
requirement advocated by Panasonic that VLP devices include sensing
technology as it does not believe that such a complex solution is
necessary to achieve the protection requirements needed for all users
in the band. Moreover, any new sensing technology often requires long
development cycles along with extended testing to ensure proper
operation, which would only delay the benefits that VLP devices can
provide.
62. As discussed above, the Commission remains convinced that the -
27 dBm/MHz out-of-band emission level at the lower edge of U-NII-5 will
protect C-V2X operations below 5925 MHz and adopt that level for VLP
devices. This will create a consistent out-of-band limit for all 6 GHz
unlicensed devices throughout the 6 GHz band.
3. Prioritization of Operations on Channels Above 6105 MHz
63. The Commission is mindful of the concerns from the auto
industry regarding the potential for harmful interference to automotive
safety systems operating below the U-NII-5 band. For example, the
proponents of the compromise proposal propose that VLP devices
prioritize unlicensed operation in channels above 6105 MHz (i.e., the
top edge of the first 160 megahertz wide channel in the Institute of
Electrical and Electronics Engineers (IEEE) band plan) before operating
below 6105 MHz and that manufacturers submit with their equipment
authorization application a declaration that the equipment complies
with this prioritization rule.
[[Page 887]]
64. To ensure that safety of life services below the U-NII-5 band
are protected from harmful interference, the Commission adopts the
suggestion from the compromise proposal to require VLP devices to
prioritize spectrum above 6105 MHz. The Commission disagrees with NAB
that this is inconsistent with its previous decision not to exclude VLP
devices from a portion of the 6 GHz band to protect electronic news
gathering (ENG) operations as this requirement does not prohibit
operation below 6105 MHz; it merely requires that devices seek to
operate in the spectrum above that frequency first before operating
below it. Although under this approach, there may be fewer VLP devices
operating on the spectrum below 6105 MHz, many devices will still
operate on that spectrum and the Commission does not expect abnormal
concentrations of VLP devices in U-NII-6 and U-NII-8 where ENG operates
as devices would still naturally spread across the available spectrum.
E. Other Matters
65. Restrictions on Very Low Power Device Use on Aircraft, Boats,
and Oil Platforms. Because VLP access points can operate in motion,
unlike standard power and LPI devices that the rules limit to
stationary operation, the Commission will permit VLP devices to operate
in terrestrial land-based vehicles, including cars, buses, trains, etc.
The Commission will also not prohibit VLP device use on boats in
contrast to its decision to prohibit standard power and LPI devices
from operating on boats. That decision stemmed from a request from the
National Academy of Sciences' Committee on Radio Frequencies (CORF)
seeking protection for Earth Exploration Satellite Service (EESS)
remote sensing operations over oceans. Given that VLP devices will
operate at much lower power levels than LPI and standard power devices,
and many boaters, particularly recreational boaters operate either on
inland lakes and waterways or in close proximity to the coastline, the
Commission does not believe that they will present an interference
threat to EESS sensing over the oceans. However, the Commission plans
on seeking comment on whether any restrictions should be put in place
for VLP operation on boats. The Commission will continue to prohibit 6
GHz devices, including VLP devices, from operating on oil platforms
because EESS operations in this band mainly include oceanic sensing,
and operation of VLP devices on oil platforms could potentially
interfere with passive and active sensing operations over the oceans
and coastal where these oil rigs tend to be concentrated. The
Commission also notes that ocean based oil platforms, are located
anywhere from a few hundred meters to a few hundred miles off of the
coast where EESS operations are monitoring critical data oceanographic
and weather phenomenon. However, the Commission plans on seeking
comment on whether this restriction should be eliminated.
66. Consistent with the Commission's decision in the 6 GHz Order to
prohibit standard power and LPI devices from operating in low flying
aircraft and unmanned aircraft systems (UAS) (i.e., drones), the
Commission similarly prohibits such operation for VLP devices. Use on
such platforms presents novel propagation paths and introduces the
potential for causing harmful interference to fixed microwave
receivers, which are typically located on towers and rooftops. Unlike
operation that may occur outside on a balcony above ground level,
operation on a low flying aircraft or UAS may not have buildings or
other structures nearby to attenuate signals and thus will have a
higher probability of having a line-of-sight path to an incumbent
receiver location resulting in a higher potential for causing harmful
interference. Hence, the Commission will apply the same aircraft
restriction to VLP devices as it adopted for LPI and standard power
devices. VLP devices will not be permitted on aircraft, except in large
aircraft while flying above 10,000 feet. Consistent with the
Commission's decision in the 6 GHz Order, it believes that operating at
those altitudes along with attenuation provided by an aircraft's
fuselage will keep signal levels to such a low level at incumbents'
receivers as to pose an insignificant harmful interference risk. The
Commission will permit VLP devices operating on aircraft above 10,000
feet to operate across the 5.925-6.425 GHz band. This is consistent
with the 6 GHz Order, which restricted LPI operation on large aircraft
flying above 10,000 feet to the U-NII-5 band to prevent harmful
interference to radio astronomy and EESS operations in the U-NII-6, U-
NII-7, and U-NII-8 bands. VLP devices will also not be permitted to be
used for control of or communications with unmanned aircraft systems.
67. 57-71 GHz Band. CTIA opposes expanding AFC-free VLP unlicensed
operations in the 6 GHz band and instead proposes that unlicensed
proponents consider the 57-71 GHz band for VLP operations. We decline
to prohibit VLP device operations in the U-NII-5 and U-NII-7 portions
of the of the 6 GHz band in favor of the 57-71 GHz band. The
Commission's policy has been to provide as much flexibility for
spectrum users--both licensed and unlicensed--to use spectrum bands
that best meet their needs based on their business case and expected
use cases. VLP operations are no different and, as explained in the
Second Report and Order, the Commission believes that permitting VLP
operations in the 6 GHz band meets that goal. The rules the Commission
is adopting provides flexibility for VLP operations while still
protecting authorized services from harmful interference. Furthermore,
the Commission notes that the 57-71 GHz band has flexible rules for
unlicensed operations and that manufacturers could develop similar
devices to 6 GHz VLP devices under those rules should they determine
that it is both feasible and would meet consumer demand.
68. LPI and standard power devices as substitute for VLP. AT&T
points to claims by VLP device proponents that 90% of these devices
will operate indoors to argue that VLP devices are not necessary to
address the use cases purportedly supported by the VLP rules. AT&T also
claims that VLP device proponents essentially concede that the burden
of adding AFC capability to VLP devices would be minimal, pointing to a
filing by Apple, Broadcom, Google, and Meta that discusses implementing
exclusion zones for VLP devices.
69. The Commission does not agree with AT&T's rationale that if 90%
of VLP use is assumed to be indoors, there is no utility in enabling
outdoor VLP device operation. VLP proponents describe portable battery-
powered consumer products as a primary use case for these devices, and
apportioning significant battery resources to the overhead necessary to
operate pursuant to an AFC could reduce utility of these devices to the
point that they would be infeasible. In addition, as discussed above,
the Commission disagrees with AT&T's assertion that there is no cost to
implement an AFC capability in VLP devices. Adding AFC capability to
these small battery-powered portable device would likely increase their
complexity and, correspondingly, their cost. The Commission also agrees
with Apple, Broadcom, and Meta that VLP devices will be suitable for
applications that require direct communications between client devices
and to support mobility that may require devices to transition between
indoor and outdoor use. Therefore, the Commission finds AT&T's
contention to be without merit.
70. Rule Corrections. The Commission is making two minor changes to
Sec. 15.407 to correct cross-references that were
[[Page 888]]
inadvertently not updated when the Commission previously renumbered
paragraphs in this section. Specifically, the Commission corrects the
cross-reference in the introductory text of Sec. 15.407(b) to
reference paragraph (b)(10) rather than paragraph (b)(7), and the
Commission corrects the cross-reference in Sec. 15.407(l)(2)(ii) to
reference paragraph (b)(7) rather than paragraph (b)(6).
F. Benefits and Cost
71. As discussed above, the Commission adopts rules to permit VLP
devices to operate in the U-NII-5 and U-NII-7 portions of the 6 GHz
band while protecting the licensed services that operate in the band
from harmful interference. Enabling new unlicensed use types in the U-
NII-5 and U-NII-7 bands will yield important economic benefits and will
allow more extensive use of technologies, such as Wi-Fi and Bluetooth,
by American consumers. Consumers are using more and more data, on
average, and this is expected to continue to grow significantly. One
report estimated that in 2021, the economic benefits associated with
Wi-Fi in the United States was valued at almost $979 billion and that
by 2025, 40% of Wi-Fi traffic will rely on 6 GHz. Another report
estimated that making the 6 GHz band accessible to VLP devices would
produce over $39 billion in economic value over five years. Even if the
rules that the Commission adopts herein lead to expected benefits of 5%
of $39 billion, or approximately $2 billion--a figure the Commission
finds to be below the likely benefits of these rules--the expected
benefits will be well in excess of the costs that we estimate.
72. Because there are presently no VLP devices in operation, the
rules that the Commission promulgate does not have cost implications
for the existing unlicensed device ecosystem. And because the harmful
interference risk to incumbent operators is insignificant and the
Commission is not imposing any specific requirements on any incumbent
operator, there is also no cost implication on them. Thus, by
promulgating these rules to enable VLP devices to operate in the U-NII-
5 and U-NII-7 portions of the 6 GHz band, significant economic benefits
will be bestowed on the American public.
Memorandum Opinion and Order on Remand
73. Introduction. In this order, the Commission addresses a remand
from the United States Court of Appeals for the District of Columbia
Circuit concerning the rules that govern the use of unlicensed devices
in the 6 GHz band (AT&T Servs., Inc. v. FCC, 21 F.4th 841 (D.C. Cir.
2021)). After rejecting a number of challenges to the rules, the court
of appeals remanded a single narrow issue for further consideration.
Specifically, the court directed us to consider whether, in light of
broadcasters' claims that they have experienced interference from
unlicensed devices in the 2.4 GHz band, a portion of the 6 GHz band
should be reserved for mobile broadcast operations. For the reasons set
forth below, the Commission concludes that broadcasters'
unsubstantiated claims of interference in the 2.4 GHz band do not
warrant any modification of our 6 GHz rules.
74. Background. In the spring of 2020, the Commission adopted rules
to make 1200 megahertz of spectrum available for use by unlicensed
devices in the 6 GHz band (5.925-7.125 GHz). Several parties, including
NAB, filed petitions for review of the rules in the D.C. Circuit. The
court denied the petitions for review ``in all respects save one.'' The
sole issue that the court remanded concerned NAB's assertion that
``after the Commission allowed unlicensed access in the 2.4 GHz band,
`a contention-based protocol . . . failed to protect . . . licensed
users[,] . . . rendering that band partially unusable.' '' Based on
broadcasters' concern that unlicensed devices could create similar
problems in the 6 GHz band, NAB had asked the Commission to ``reserve a
sliver of [the] 6 GHz band for licensed mobile [broadcast] operation.''
In the court's view, ``the Commission failed adequately to respond to
[this] request'' because it ``never responded'' to NAB's concerns about
interference in the 2.4 GHz band. ``Given the Commission's failure to
respond'' to these concerns, the court concluded that ``further
explanation is called for.'' Accordingly, the court ``remand[ed] to the
Commission for it to respond to [NAB's] concerns about interference in
the 2.4 GHz band.''
75. Discussion. In response to the court's remand, the Commission
has further examined NAB's claims concerning the 2.4 GHz band, and the
Commission finds that those claims lack merit. The record in this
proceeding contains no concrete evidence that unlicensed Wi-Fi devices
have caused harmful interference to mobile broadcast operations in the
2.4 GHz band. By contrast, the record contains concrete evidence that
contention-based protocols would be effective in the 6 GHz band.
Consequently, the Commission finds that NAB's claims of interference in
the 2.4 GHz band do not warrant any modifications to its 6 GHz rules.
76. In a series of letters filed before the 6 GHz rules were
adopted, NAB told the Commission that a contention-based protocol
requirement for unlicensed devices in the 2.4 GHz band had not
protected broadcasters and that this experience should lead the
Commission to conclude that a contention-based protocol likewise would
not protect broadcasters from harmful interference in the 6 GHz band.
NAB claimed that ``the penetration of Wi-Fi has so polluted the shared
portion of the 2.4 GHz band as to render it unusable for'' ENG
operations. But NAB offered no specific evidence to support this broad
claim. Instead, NAB cited comments filed in this proceeding by the
Engineers for the Integrity of Broadcast Auxiliary Services Spectrum
(EIBASS) in February 2019.
77. Although EIBASS asserted in its February 2019 comments that
``part 15 devices have a long history of causing chronic interference
to TV BAS [Broadcast Auxiliary Service] operations'' on certain
channels in the 2.4 GHz band, it offered only two very specific pieces
of evidence regarding this claim: an unsubstantiated account of an
incident that allegedly occurred in a single market more than a decade
ago and a spectrum analyzer screenshot from a specific location
purporting to show that Wi-Fi caused an increase in the 2.4 GHz band
noise floor. EIBASS described a presentation made by the BAS frequency
coordinator for Phoenix, Arizona, during a conference of broadcast
engineers in April 2004. According to EIBASS, the Phoenix coordinator
stated during the April 2004 presentation that ``about every six months
or so,'' one of the four ENG receive-only sites in the Phoenix area
``becomes unusable'' for certain channels in the 2.4 GHz band ``because
of the proliferation of 2.4 GHz WiFi devices at the site.''
78. Even if the Commission were persuaded that broadcasters in the
Phoenix area had experienced interference in the 2.4 GHz band nearly
two decades ago, as EIBASS claimed, this isolated incident would not
convince us that the Commission needs to take additional measures that
would affect the entirety of the U.S. to protect broadcasters from
harmful interference in the 6 GHz band. Even assuming that harmful
interference did in fact occur, the Commission has no way of verifying
that Wi-Fi devices caused the problem. If the alleged interference did,
in fact, occur, the Commission notes that many unlicensed part 15 non-
Wi-Fi devices also operate in the 2.4 GHz band, and
[[Page 889]]
those devices do not use a contention-based protocol. Similarly,
industrial, scientific, and medical (ISM) devices operate on a primary
basis in the 2.4 GHz band. Because EIBASS does not attribute any
alleged harmful interference to any specific Wi-Fi device(s) and does
not appear to consider any of the other numerous devices operating in
the band without using a contention-based protocol, the Phoenix
incident does not support NAB's assertion that a contention-based
protocol failed to prevent interference in the 2.4 GHz band.
79. The other evidence that EIBASS provided was a spectrum analyzer
screenshot that was captured at an ENG receive-only site in Phoenix in
2013. While this screenshot shows that some type of signal could have
been present in the 2.4 GHz band at that time, it does not provide
evidence of what devices may be causing any noise floor increase nor
that a contention-based protocol would have failed to protect BAS
receivers in the band. Moreover, as this screenshot is merely an
indication of the spectrum at a single point in time, it offers no
indication as to the behavior of a device employing a contention-based
protocol when in the vicinity of a BAS transmitter in the band. Given
the limited information this screenshot conveys, it provides no grounds
to support NAB's assertion that a contention-based protocol had failed
to prevent interference in the 2.4 GHz band.
80. Furthermore, even if the devices that EIBASS alleged were
causing interference in Phoenix used a contention-based protocol, the
Commission cannot determine from the sparse evidence in the record
whether those devices were operating in compliance with the
Commission's part 15 rules. Notably, the contention based protocol used
by Wi-Fi devices is part of the IEEE 802.11 standard and not required
by the Commission's rules nor do the Commission's rules limit such
devices to indoor locations. Because of the lack of a Commission-
mandated requirement for a contention-based protocol or indoor
operation on 2.4 GHz devices, and no insight into whether devices in
the Phoenix area at the time of the alleged interference were actually
using such a protocol or operating indoors, it is impossible to draw
any conclusions from those operations and the operations anticipated in
the 6 GHz band. Thus, the alleged Phoenix incidents shed no light on
the relevant question raised by NAB: that is, whether the purported
experience regarding potential harmful interference to BAS devices in
the 2.4 GHz band has any relevance to the potential for such
interference from LPI devices in the 6 GHz band. Additionally, as an
added safeguard and as several commenters note, the 6 GHz rules impose
much lower power limits on unlicensed LPI devices than the 2.4 GHz
rules do.
81. In contrast to NAB's unsubstantiated claims of harmful
interference in the 2.4 GHz band, the record persuades us that ``the
risk of harmful interference to indoor electronic news gathering
receivers from indoor unlicensed devices'' in the 6 GHz band ``is
insignificant.'' A study by Apple, Broadcom, et al. ``simulated the
receive power level from electronic news gathering transmitters at 20
unlicensed access points operating within the U.S. House of
Representatives chamber. The results of this simulation demonstrate[d]
that, even at the lowest electronic news gathering transmit power
level, all unlicensed access points would detect the electronic news
gathering signal at greater than -62 dBm and therefore not transmit co-
channel.'' This study ``confirm[ed]'' that contention-based protocols
``could be used to mitigate interference to indoor electronic news
gathering receivers'' in the 6 GHz band.
82. Because the record contains no substantial evidence of harmful
interference to broadcast operations in the 2.4 GHz band, the
Commission finds no basis for NAB's assertion that a contention-based
protocol failed to protect broadcasters from interference in that band,
much less under the parameters established for operation in the 6 GHz
band. As the Commission noted in the 6 GHz Order, ``Wi-Fi devices have
been deployed'' in the 2.4 GHz band ``in abundance for well over 20
years.'' For most of that time, the 2.4 GHz band was the primary band
used by Wi-Fi devices. If (as NAB and others have claimed) interference
from Wi-Fi devices prevented broadcasters from using portions of the
2.4 GHz band, the Commission would expect the record to reflect
evidence of numerous instances of such interference. Yet apart from an
unsubstantiated account of an alleged incident in Phoenix almost two
decades ago and a spectrum analyzer screenshot captured in Phoenix more
than a decade ago, the record contains no specific evidence that any
broadcaster has experienced harmful interference from unlicensed Wi-Fi
devices in the 2.4 GHz band. Moreover, neither NAB nor any other party
has cited a single complaint filed with our Enforcement Bureau by any
broadcaster alleging interference by unlicensed Wi-Fi devices in the
2.4 GHz band. The absence of any such complaints undermines NAB's
contention that interference from unlicensed Wi-Fi devices is a serious
problem for broadcasters in the 2.4 GHz band.
83. Following the remand, the Society of Broadcast Engineers (SBE)
and EIBASS attempted to supplement the record by presenting new
evidence of harmful interference in the 2.4 GHz band. Such evidence
falls outside the scope of this remand proceeding. The narrow question
presented by the court's remand is whether the Commission adequately
considered NAB's concerns about interference in the 2.4 GHz band when
it adopted the 6 GHz rules. In this context, the relevant record is
``the record before the agency at the time of its decision.''
84. In any event, even assuming that the new evidence proffered by
SBE and EIBASS were properly before us, this evidence does not persuade
us that Wi-Fi devices have caused harmful interference to broadcast
operations in the 2.4 GHz band, much less at the far lower power at
which Wi-Fi operations are required to operate in the 6 GHz band. SBE
asserts that it conducted an ``informal survey'' in which local
frequency coordinators reported ``harmful interference from Wi-Fi
systems [in the 2.4 GHz band] . . . in at least 13 markets.'' But as
Apple, Broadcom, et al. point out, SBE's ``informal survey'' was
``backed in most cases by no supporting evidence or incident
descriptions.'' The only evidence offered by SBE to support its
``informal survey'' is a spectrum plot that purports to show
interference in Milwaukee. The Commission agrees with Apple, Broadcom,
et al. that this spectrum plot does not constitute ``meaningful
technical evidence'' because it contains ``no supporting detail''
concerning how the measurement of interference in Milwaukee was made.
In particular, the Commission notes that SBE offers ``no explanation
why'' it attributes the alleged interference in Milwaukee ``to Wi-Fi,
rather than to the many other technologies operating in the 2.4 GHz
band that do not use a contention-based protocol.'' The same is true of
EIBASS's comparison of the noise floors for mobile broadcast operations
at 2 GHz and 2.5 GHz. Although EIBASS claims that part 15 Wi-Fi devices
are responsible for the higher noise floor at 2.5 GHz, the higher noise
floor could also be attributable to ``the many other technologies
operating in the 2.4 GHz band that do not use a contention-based
protocol.''
85. The post-remand submissions by SBE and EIBASS also fail to cite
any complaints filed with our Enforcement
[[Page 890]]
Bureau claiming that Wi-Fi devices caused harmful interference to
mobile broadcast operations in the 2.4 GHz band. The absence of any
such complaints casts further doubt on the assertions made by NAB and
its supporters that broadcasters have routinely experienced such
interference.
86. In sum, despite NAB's claims that interference issues in the
2.4 GHz band are pervasive and longstanding, the record contains no
credible evidence of such interference. The specific incident of
alleged interference cited in the record occurred about two decades ago
in Phoenix, and it was never reported to the Commission's Enforcement
Bureau. EIBASS's sketchy description of the details of that incident
does not provide us with enough information to draw any firm
conclusions about how--or even whether--interference occurred. The
spectrum analyzer screenshot showing an increase in the noise floor in
Phoenix more than a decade ago also lacks the details needed to reach a
conclusion about whether harmful interference was occurring. Given the
absence of any concrete evidence that broadcasters have experienced
harmful interference in the 2.4 GHz band or in the 6 GHz band, where
LPI devices have been operating since December 2020, and in light of
the substantial record evidence demonstrating that there is no
significant risk of harmful interference given the constraints under
which Wi-Fi devices are required to operate in the 6 GHz band, the
Commission rejects NAB's contention that broadcasters' experience with
interference in the 2.4 GHz band justifies the reservation of a portion
of the 6 GHz band for mobile broadcast operations.
87. Conclusion. For the foregoing reasons, the Commission concludes
that NAB's unsubstantiated claims of interference in the 2.4 GHz band
do not justify any modifications to its 6 GHz rules to provide
broadcasters with further protections from harmful interference. The
Commission reaffirms that the rules adopted in the 6 GHz Order
eliminate any significant risk of harmful interference to mobile
broadcast operations and other incumbent licensed services in the 6 GHz
band. Therefore, the Commission declines to adopt NAB's proposal to
reserve part of the 6 GHz band for the exclusive use of mobile
broadcast operations.
Ordering Clauses
1. Accordingly, it is ordered, pursuant to sections 2, 4(i), 302,
and 303 of the Communications Act of 1934, as amended, 47 U.S.C. 152,
154(i), 302a, and 303, the Second Report and Order and Memorandum
Opinion and Order on Remand, is hereby adopted.
2. It is further ordered, pursuant to sections 4(i), 4(j), 201,
302, and 303 of the Communications Act of 1934, as amended, 47 U.S.C.
154(i), (j), 201, 302a, 303, that the Memorandum Opinion and Order on
Remand is hereby adopted.
3. It is further ordered that the amendments of the Commission's
rules as set forth in Appendix A of the Second Report and Order are
adopted, effective 60 days from the date of publication in the Federal
Register.
4. It is further ordered that the Memorandum Opinion and Order on
Remand shall become effective thirty (30) days after publication in the
Federal Register.
5. It is further ordered that the Office of the Secretary,
Reference Information Center, shall send a copy of the Second Report
and Order including the Final Regulatory Flexibility Analysis, to the
Chief Counsel for Advocacy of the Small Business Administration.
6. It is further ordered that the Office of Managing Director,
Performance Program Management shall send a copy of the Second Report
and Order in a report to be sent to Congress and the Government
Accountability Office pursuant to the Congressional Review Act, 5
U.S.C. 801(a)(1)(A).
List of Subjects in 47 CFR Part 15
Communications equipment, Radio, Reporting and recordkeeping
requirements.
Federal Communications Commission.
Marlene Dortch,
Secretary.
Final Rules
For the reasons discussed in the preamble, the Federal
Communications Commission amends 47 CFR part 15 as follows:
PART 15--RADIO FREQUENCY DEVICES
0
1. The authority citation for part 15 continues to read as follows:
Authority: 47 U.S.C. 154, 302a, 303, 304, 307, 336, 544a, and
549.
0
2. Section 15.403 is amended by adding the definition of ``Very low
power device'' in alphabetical order, to read as follows:
Sec. 15.403 Definitions.
* * * * *
Very low power device. For the purpose of this subpart, a device
that operates in the 5.925-6.425 GHz and 6.525-6.875 GHz bands and has
an integrated antenna. These devices do not need to operate under the
control of an access point.
0
3. Section 15.407 is amended by:
0
a. Removing the headings from paragraphs (a)(1) and (3);
0
b. Redesignating paragraphs (a)(9) through (12) as paragraphs (a)(10)
through (13);
0
c. Adding a new paragraph (a)(9);
0
d. Revising paragraphs (b) introductory text, (c), and (d)(1);
0
e. Removing and reserving paragraph (d)(2);
0
f. Revising paragraph (d)(6);
0
g. Adding paragraphs (d)(8) through (10); and
0
h. Revising paragraph (l)(2)(ii).
The revisions and additions read as follows.
Sec. 15.407 General technical requirements.
(a) * * *
(9) For very low power devices operating in the 5.925-6.425 GHz and
6.525-6.875 GHz bands, the maximum power spectral density must not
exceed -5 dBm e.i.r.p in any 1-megahertz band and the maximum e.i.r.p
must not exceed 14 dBm.
* * * * *
(b) Undesirable emission limits. Except as shown in paragraph
(b)(10) of this section, the maximum emissions outside of the frequency
bands of operation shall be attenuated in accordance with the following
limits:
* * * * *
(c) Transmission discontinuation requirement. The device shall
automatically discontinue transmission in case of either absence of
information to transmit or operational failure. The provisions in this
paragraph (c) are not intended to preclude the transmission of control
or signaling information or the use of repetitive codes used by certain
digital technologies to complete frame or burst intervals. Applicants
shall include in their application for equipment authorization a
description of how the requirement in this paragraph (c) is met.
(d) * * *
(1) Operational restrictions include:
(i) Oil platforms. Operation of standard power access points, fixed
client devices, very low power devices, and indoor access points in the
5.925-7.125 GHz band is prohibited on oil platforms.
(ii) Land vehicles. Operation of standard power access points,
fixed client devices, and indoor access points in the 5.925-7.125 GHz
band is prohibited on vehicles (e.g., cars, trains).
(iii) Boats. Operation of standard power access points, fixed
client
[[Page 891]]
devices, and indoor access points in the 5.925-7.125 GHz band is
prohibited on boats.
(iv) Aircraft. Standard power access points, fixed client devices,
very low power devices, and indoor access points in the 5.925-7.125 GHz
band are prohibited from operating on aircraft, except that very low
power devices and indoor access points are permitted to operate in the
5.925-6.425 GHz bands in large aircraft while flying above 10,000 feet.
(v) Unmanned aircraft systems. Operation of transmitters in the
5.925-7.125 GHz band is prohibited for control of or communications
with unmanned aircraft systems.
* * * * *
(6) All U-NII transmitters, except for standard power access
points, operating in the 5.925-7.125 GHz band must employ a contention-
based protocol.
* * * * *
(8) Very low power devices may not employ a fixed outdoor
infrastructure. Such devices may not be mounted on outdoor structures,
such as buildings or poles.
(9) Very low power devices must prioritize operations on
frequencies above 6.105 GHz prior to operating on frequencies between
5.925 GHz and 6.105 GHz.
(10) Very low power devices operating in the 5.925-6.425 and 6.525-
6.875 GHz bands shall employ a transmit power control (TPC) mechanism.
A very low power device is required to have the capability to operate
at least 6 dB below the maximum EIRP power spectral density (PSD) value
of -5 dBm/MHz.
* * * * *
(l) * * *
(2) * * *
(ii) The AFC system must use -6 dB I/N as the interference
protection criteria in determining the size of the adjacent channel
exclusion zone, where I (interference) is the signal from the standard
power access point or fixed client device's out of channel emissions at
the fixed microwave service receiver and N (noise) is background noise
level at the fixed microwave service receiver. The adjacent channel
exclusion zone must be calculated based on the emissions requirements
of paragraph (b)(7) of this section.
* * * * *
[FR Doc. 2023-28006 Filed 1-5-24; 8:45 am]
BILLING CODE 6712-01-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on January 8, 2024.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.