[SOIS-WIR] Ensuring Lunar and Martian In-situ PNT Coexistence with Surface Wireless by Respecting SFCG Recommendations

[Stephen Braham]

Thanks J-L!

One small point--you talk about the 5G channel allocation, and there 
seems to be a little bit of a confusion between EARFCN in the 3GPP 
/standard /and how spectrum works in compliant 3GPP /implementations 
/(so when GSMA, ITU, and others are taken into account). You can't, 
generally, adjust 3GPP bands in 5 kHz steps. Basically, a 3GPP device 
needs to search for carriers on a very few frequencies, which is built 
into GSMA and other requirements that are placed into firmware and 
hardware certification. So, if a band block allocation, in terms of ITU 
or regional (FCC, etc.) blocks, intersects with these guard bands, it's 
effectively removed, eh?

Also, in terms of measurements, are you measuring /actual /impact or 
simply spectral power density of Wi-Fi and 3GPP? Because, of course, in 
the recent 5G FAA PNT/altimeter (power density) via FCC limits in the US 
(actual interference impact) debacle, it was found that impact were 
massively less that Rx power density would suggest. Basically because a 
PNT integrates over a large BW, and 5G is an OFDM signal--so, because of 
the "O" (orthogonality), a PNT receiver usually integrates an OFDM 
interferer to many dB less than its power density (a perfect OFDM would 
integrate to zero interference power if integrated over a multiple of 
its subcarrier width at 0 m/s, but, of course, doppler and always having 
a fraction of a subcarrier over does leave left-over interference, to 
something of the order total RxP/number of subcarriers, which is usually 
600 to ~2400, linearly)? Exactly why each OFDM subcarrier can be packed 
so close without interference, inside the full OFDM signal. Though, of 
course, impact would depend on how well a lunar PNT receiver compares to 
a commercial FAA-approved one (but the latter turned out to be cheap and 
didn't even filter outside their own band, and still had little impact 
from actual 5G ground basestations on altimeters at aircraft 
velocities!). Note, we'd expect suit Wi-Fi/3GPP to onboard PNT velocity 
difference/doppler non-orthorgonality to be zero, and other velocities 
to be low, as long as it was surface-surface. 5G-NTN is a far bigger 
problem, if the UE is pre-adjusting Doppler, making the OFDM uplink 
non-orthogonal, and thus potentially causing interference. Most 
implementations are doing those corrections at the orbital end, though, 
so hopefully not an issue. Albeit quality of implementation still 
matters-a badly non-linear transmitter or receiver can be a real issue, 
as nonlinear processing of OFDM destroys linearity! As we found when one 
of our sub-Arctic LTE base stations, in lunar-like terrain, developed a 
PA non-linearity (hardware failed, rather than out-of-spec) during a 
sub-Arctic winter! Still operating, but now with a new PA, BTW.

       Steve

On 2025-09-29 07:05, Issler Jean-Luc via SOIS-WIR wrote:
>
> Dear all,
>
> I sent you a few weeks ago a ION GNSS+ paper untitled : “Ensuring 
> Lunar and Martian In-situ PNT Coexistence with Surface Wireless by 
> Respecting SFCG Recommendations”.
>
> This paper has been slitly updated.
>
> Please find hereattached the new version of this paper, to replace the 
> previous version  if you do not mind.
>
> Have a nice day; Very Best Regards
>
> Jean-Luc
>
>
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-- 
Stephen P. Braham, BSc, PhD, ARCS	Director, PolyLAB
warp at polylab.sfu.ca			Simon Fraser University
(tel) 778 782-7981			Harbour Centre Campus
(fax) 778 782-7980			Vancouver, BC, Canada
http://team.polylab.sfu.ca/~warp/	
Twitter: warp				Facebook: sbraham
Callsign: VA7TMI

    PolyLAB: From the Classroom to Space,http://polylab.sfu.ca/

At Simon Fraser University, we live and work on the unceded
traditional territories of the Coast Salish peoples of the
xʷməθkwəy̓əm (Musqueam), Skwxwú7mesh (Squamish), and
Səl̓ílwətaɬ (Tsleil-Waututh) Nations.
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