[Ground-station] FPGA meetup + Regulatory (900 MHz) work session

[Michelle Thompson]

Proposed introduction for draft comment (900 MHz band NPRM):

The Federal Communications Commission is committed to developing spectrum
sharing models that enable expanded and effective use of our airwaves.
Effective spectrum sharing is realized when multiple users and operators
can successfully coexist within the same geographic area. Guidance on the
next generation of spectrum strategy, including details about dynamic
spectrum sharing demonstrations, reports, and timelines, can be found in
the NTIA’s National Spectrum Strategy.

A diversity of users and operators on a band, bringing in new products,
launching new services, and exploring new use cases is an indication of
successful spectrum management. Successful spectrum management is a
necessary but insufficient condition for a vibrant and healthy radio
service. Technical feasibility, cost, whether consumers adopt the product
or service, and many other factors are also critical to success. However,
bad regulations can short even the very best product designs to ground. A
failure of regulations drives away users and operators and prevents new
products and use cases from getting past the prototype stage.

The proposal asserts that the 900 MHz band is “underutilized”. The proposal
asserts that changing 900 MHz regulations is required in order for their
economically infeasible product to succeed. The proposal asserts that only
NextNav products can provide a particular type of PNT GPS backup service
and without NextNav the 900 MHz band will “continue to be underutilized”
and “the country will continue to lack terrestrial PNT”. The proposal
claims that the service is “state of the art and best in class”, that their
service is “transformative”, that they are the only game in town, and that
they deserve the 900 MHz band to be reconfigured just for them. The
proposal asks for a spectrum swap and license consolidation, explaining
that they already control so many licenses that it’s just common sense that
they should be awarded a significant band reconfiguration.

Even if the assertions were all true, NextNav’s success is completely
dependent on integration with 5G products and successful partnerships with
5G operators. However, there are no demonstrated integrations, no announced
partnerships, no field tests, and no interference mitigation plans. There
is one simulation that confirmed an uncontroversial relationship between
bandwidth and performance. Worse, the proposal essentially invites 5G
networks to “add mobile broadband capacity” to the band.
What is stopping 5G operators from implementing terrestrial PNT on their
own hardware, on their existing allocations, by using the 5G protocols that
NextNav describes? Why would 5G operators include yet another radio for 900
MHz in their chipsets and software stack? What is the economic incentive
for 5G to buy NextNav’s products? Why 900 MHz instead of 600, 700, or 800
MHz?

The proposal is not aligned with modern spectrum sharing strategies. The
proposal fails to support the technical claims. The proposal does not
justify customizing the 900 MHz band for one company’s future product.
Especially when that product has a very high likelihood of causing
interference to current innovative and educational amateur use of the band.

Given the transmit powers listed in the proposal, and assuming physical
deployments including mobile broadband, all incumbents would be negatively
affected with no discernible upside for any of them and no options for
sharing. Ignoring innovative and educational activity, by falsely claiming
that it doesn’t exist, does not lead to successful sharing, cooperation,
and coexistence.

Each point is then supported by specific quotes or evidence, especially
including Ed Friesema's work on appendix A.

-Michelle Thompson




On Tue, Sep 3, 2024 at 9:11 AM Michelle Thompson <
mountain.michelle at gmail.com> wrote:

> Greetings all!
>
> Get together at 1000 US Pacific. Talk about FPGA work and the 900 MHz NPRM
> comment (due 5 September).
>
> Join Zoom Meeting
> https://us02web.zoom.us/j/86298821528?pwd=zKZhzlQ8lOvkpJDuETFCbV7TazVl1D.1
>
> Meeting ID: 862 9882 1528
> Passcode: 803305
>
>
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