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<p>Perhaps worth remembering that they don't have to engineer the
final system right now. Consider that:</p>
<p>- Building ground station gateways costs money, but as the number
of subscribers grows, so does the income stream that allows for
ground station construction.<br>
- Gateway ground stations, if generally kept close to users, at
least where there are lots of users, don't have the problem that
there's no land to put them on as there aren't normally lots of
users in the middle of the sea.<br>
- Where there are more than 10k users, someone will generally put
a fibre optic cable there or at least think hard about how they
can get that done. We've seen this widely in the Pacific, where
such islands now generally have fibre (with some notable
exceptions). Once you have fibre, there's no reason why you can't
have a LEO ground station there. So you can generally always build
more <br>
- Constellations that are short of capacity can be added to
incrementally. Remember Starlink is at a very early stage of what
they're planning.<br>
- Satellite capacity depends on a lot of things, from on-board
processing capacity to the bandwidth of the uplinks and downlinks
and the received signal levels on those. Current Starlink gateway
antennas are tiny by satellite infrastructure standards, but that
doesn't preclude bigger antennas and more gateways for the future,
which allows more satellites to be provided with direct gateway
links.</p>
<p>In some ways, this evolution mirrors that of mobile networks. In
the early stage of mobile network evolution, the providers aimed
at getting coverage with the least number of base stations from
the highest hills and buildings available. These never had the
potential to provide the capacity that today's networks have, so
as the networks evolved, they moved down from the lofty heights to
the bottom of the valleys, cashing in on improved frequency re-use
potential (you could re-use the same frequency a valley over, you
see, because the ridge between yours and theirs meant that signals
wouldn't interfere). It also meant less path loss to the end users
(so more battery life for them). Not to mention fewer lawsuits
from people who were worried about large towers irradiating their
kids. The cost of those lawsuits, by the way, was seen simply as
something to factor in when making engineering decisions.<br>
</p>
<div class="moz-cite-prefix">On 22/02/2022 8:20 pm, Dick Roy wrote:<br>
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<p class="MsoNormal"><b><font size="2" face="Tahoma"><span style="font-size:10.0pt;
font-family:Tahoma;font-weight:bold">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size:10.0pt;font-family:Tahoma"> Starlink
[<a class="moz-txt-link-freetext" href="mailto:starlink-bounces@lists.bufferbloat.net">mailto:starlink-bounces@lists.bufferbloat.net</a>] <b><span style="font-weight:
bold">On Behalf Of </span></b>Mike Puchol<br>
<b><span style="font-weight:bold">Sent:</span></b>
Monday, February 21, 2022
9:35 PM<br>
<b><span style="font-weight:bold">To:</span></b> Daniel
AJ Sokolov; David Lang<br>
<b><span style="font-weight:bold">Cc:</span></b>
<a class="moz-txt-link-abbreviated" href="mailto:starlink@lists.bufferbloat.net">starlink@lists.bufferbloat.net</a><br>
<b><span style="font-weight:bold">Subject:</span></b>
Re: [Starlink] Starlink
Roaming</span></font><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><font size="3" face="Times New Roman"><span style="font-size:12.0pt">Actually, laser links
would make gateway connectivity *worse*. If we take
the scenario attached, one
gateway is suddenly having to serve traffic from all
UTs that were not
previously under coverage. <br>
<br>
A satellite under full load can saturate two gateway
links by itself. If you
load, say, 20 satellites in an orbital plane, onto a
single gateway, over ISL,
you effectively have 5% of each satellite’s capacity
available (given an
equal distribution of demand, of course there will be
satellites with no UTs to
cover etc.).<font color="navy"><span style="color:navy"><o:p></o:p></span></font></span></font></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><i><font size="2" face="Arial" color="navy"><span style="font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic">[RR] I think
to do this analysis correctly;
one needs to consider the larger system and the
time-varying loads on the
components thereof. What you say is true; just a
bit over-simplified to be maximally
useful. Routing through complex congested networks
is well-studied problem and hnts
at possible solutions can probably be found there</span></font></i></b><b><i><font size="2" face="Wingdings" color="navy"><span style="font-size:10.0pt;font-family:
Wingdings;color:navy;font-weight:bold;font-style:italic">J</span></font></i></b><b><i><font size="2" face="Arial" color="navy"><span style="font-size:10.0pt;font-family:Arial;
color:navy;font-weight:bold;font-style:italic">)<o:p></o:p></span></font></i></b></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><font size="3" face="Times New Roman"><span style="font-size:12.0pt"><br>
<br>
Eventually they will go for optical gateways, it’s the
only way to get
enough capacity to the constellation, specially the
30k satellite version.<o:p></o:p></span></font></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><i><font size="2" face="Arial" color="navy"><span style="font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic">[RR] What do
you mean by “”optical
gateway”? An optical link from the satellite to
the ground station? That
would be real expensive at least power-wise and
unreliable.</span></font></i></b><font size="2" face="Arial" color="navy"><span style="font-size:10.0pt;font-family:Arial;
color:navy"><o:p></o:p></span></font></p>
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<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt"><br>
Best,<br>
<br>
Mike<o:p></o:p></span></font></p>
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<div name="messageReplySection">
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt">On Feb 22, 2022, 05:17 +0300, David Lang
<a class="moz-txt-link-rfc2396E" href="mailto:david@lang.hm"><david@lang.hm></a>, wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt">On Mon, 21 Feb 2022, Daniel AJ Sokolov wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt">On 2022-02-21 at 13:52, David Lang wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt"><br>
They told me that I could try it, and it may work, may
be degraded a<br>
bit, or may not work at all. They do plan to add roaming
capabilities in<br>
the future (my guess is that the laser satellites will
enable a lot more<br>
flexibility)<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt"><br>
Isn't that a very optimistic assessment? :-)<br>
<br>
Laser links are great for remote locations with very few
users, but how<br>
could they relieve overbooking of Starlink in areas with
too many users?<br>
<br>
The laser links can reduce the required density of
ground stations, but<br>
they don't add capacity to the network. Any ground
station not built<br>
thanks to laser links adds load to other ground stations
- and, maybe<br>
more importantly, adds load to the satellite that does
eventually<br>
connect to a ground station.<br>
<br>
Can laser links really help on a large scale, or are
they just a small<br>
help here and there?<o:p></o:p></span></font></p>
<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size:
12.0pt"><br>
My thinking is that the laser links will make it
possible to route the traffic<br>
from wherever I am to the appropriate ground station
that I'm registered with
as<br>
opposed to the current bent-pipe approach where, if I
move to far from my<br>
registered location, I need to talk to a different
ground station.<br>
<br>
Currently there are two limits in any area for coverage:<br>
<br>
1. satellite bandwidth<br>
2. ground station bandwidth<br>
<br>
laser links will significantly reduce the effect of the
second one.<br>
<br>
We know that they can do mobile dishes (they are testing
it currently on Elon's<br>
gulfstream, FAR more mobile that I will ever be :-) )<br>
<br>
David Lang<br>
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<pre class="moz-signature" cols="72">--
****************************************************************
Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
The University of Auckland
<a class="moz-txt-link-abbreviated" href="mailto:u.speidel@auckland.ac.nz">u.speidel@auckland.ac.nz</a>
<a class="moz-txt-link-freetext" href="http://www.cs.auckland.ac.nz/~ulrich/">http://www.cs.auckland.ac.nz/~ulrich/</a>
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