<html><head><style>body{font-family:CMU Sans Serif,Arial;font-size:14px}</style></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="font-family:CMU Sans Serif,Arial;font-size:14px; ">Hi,</div><div style="font-family:CMU Sans Serif,Arial;font-size:14px; "><br></div><div style="font-family:CMU Sans Serif,Arial;font-size:14px; ">Will quickly jump in for one of the points discussed here.</div><div style="font-family:CMU Sans Serif,Arial;font-size:14px; "><br></div><div style="font-family:CMU Sans Serif,Arial;font-size:14px; "><blockquote type="cite" class="clean_bq"><blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">but as I understand the reverse-engineering of the starlink system, a given cell <br>is currently only serviced by one satellite at a time.<br></blockquote>Are we sure here? One (classic) Dishy is served by one satellite at a time, but a cell (which can contain multiple DIshys) almost has to be serviced by multiple sats to get around obstruction issues (Starlink is now quite tolerant of these. Try to put it in a tight spot where it can't see the northern sky at your place in LA and tell me whether it still connects. If it does, then your cell gets served by multiple sats).</blockquote></div> <div><br></div>A cell is definitely served by more than one sats. In the paper I shared, we did exactly this experiment where we shielded our dish in Edinburgh from the south side so it doesnt receive connectivity from dense 53 deg orbit. The dishy received connection as long as there was a sat in 70 and 97.6 deg orbit in LoS (see fig 4). From our calculations, if your location is covered by all orbital shells of Starlink, you might receive connectivity from 15-20 sats in LoS at any given time. <div><div><br> <div class="gmail_signature"><font face="CMUSansSerif"><span style="font-style: normal; font-size: 14px;">Thanks and Regards</span></font><div><font face="CMUSansSerif"><span style="font-style: normal; font-size: 14px;"><br></span></font></div><div><font face="CMUSansSerif"><span style="font-style: normal; font-size: 14px;">Nitinder Mohan</span></font></div><div><font face="CMUSansSerif"><span style="font-style: normal; font-size: 14px;">Technical University Munich (TUM)</span></font></div><div><a href="https://www.nitindermohan.com/" style="font-style: normal; font-size: 14px;"><font face="CMUSansSerif">https://www.nitindermohan.com/</font></a></div></div> <div class="airmail_ext_on" style="color:black"><br>From: <span style="color:black">Ulrich Speidel via Starlink</span> <a href="mailto:starlink@lists.bufferbloat.net"><starlink@lists.bufferbloat.net></a><br>Reply: <span style="color:black">Ulrich Speidel</span> <a href="mailto:u.speidel@auckland.ac.nz"><u.speidel@auckland.ac.nz></a><br>Date: <span style="color:black">27. February 2024 at 11:16:45</span><br>To: <span style="color:black">David Lang</span> <a href="mailto:david@lang.hm"><david@lang.hm></a><br>Cc: <span style="color:black">starlink@lists.bufferbloat.net</span> <a href="mailto:starlink@lists.bufferbloat.net"><starlink@lists.bufferbloat.net></a><br>Subject: <span style="color:black"> Re: [Starlink] Comprehensive Measurement Study on Starlink Performance Published <br></span></div><br> <blockquote type="cite" class="clean_bq"><span><div><div></div><div>
<div class="moz-cite-prefix">On 27/02/2024 7:21 pm, David Lang
wrote:<br>
</div>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
...snip<br>
</blockquote>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
> The point though is that these sparsely populated areas
aren't where the <br>
> scalability issue arises. Capacity needs to be where the
demand for it is.<br>
<br>
I only partially agree with you here. Yes, capacity that isn't
needed doesn't <br>
matter, but I think that the capacity where there aren't other
options matters <br>
more than in the more densly populated areas where there are other
options (and <br>
I say this as a starlink user living in the Los Angeles area, a
fairly densely <br>
populated area) I use Starlink as a backup now, but I do
periodically test it <br>
and verify that it is acceptable for work + other uses.<br>
</blockquote>
The pinchpoint thus far seems to have been the suburban and
lifestyle block belts - basically where fibre doesn't reach for
whatever reason, but where people with the wealth to afford Starlink
(or fibre if it were offered) live. My bog standard example here in
NZ are your IT project manager who wants to live on a lifestyle
block out bush. They're dime a dozen here and Starlink serves them
now even when they couldn't previously get fibre. <br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
>>> If you put in fibre today, you know that by upgrading
the endpoints over <br>
>>> time, you can get orders of magnitude of extra
bandwidth if needed.<br>
>> <br>
>> If you can get fibre, you should get fibre (with starlink
as a possible <br>
>> backup). SpaceX has said many times that Starlink is
never going to be <br>
>> competitive to fibre<br>
>> <br>
>> if you can get fibre, you aren't under-connected.<br>
> Tick. But 2 billion plus can't, or at least not yet. The
question is how many <br>
> of them might Starlink & Co be able to assist in due
course?<br>
<br>
what information do you have about the distribution of these 2B
under-connected?<br>
</blockquote>
My particular "pet case" are Pacific Islanders on islands with
populations too small / poor to afford a submarine fibre connection.
These are a somewhat interesting case in that they are just a couple
of million all up I guess, with numbers shrinking as fibre does get
laid. Essentially, anyone with 10k plus population and under 1000 km
(~600 miles) to the next cable access point is now a member of the
club - having a rich nation or large diaspora backing you helps, but
beyond that it's distance, GDP and politics that govern the game.
Starlink can (and does now) serve most of the remaining islands,
however what makes life interesting here is that these islands are
often quite densely populated, which with growth in Starlink
endpoints makes for reduced capacity per user. Kiribati for example
currently sees around 10 Starlink kits arriving on every flight into
Tarawa in the western part of the country (3 flights a week). I'm
sure some more arrive by boat every few weeks - air freight is
expensive (around US$400 per unit). Some of these will no doubt go
to the outer islands, but Starlink is now having a visible presence
on roofs there (my PhD student was up there and installed one for
his family as well as two as part of our project). There is no
official service yet but regional roaming works well (while the
power is on, which it hasn't always been lately). <br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
(and as someone who just a couple years ago was on a 8m down/1m up
connection, <br>
what is the definition of 'under-connected'?, </blockquote>
That's under-connected in my book.<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz"><br>
but as I understand the reverse-engineering of the starlink
system, a given cell <br>
is currently only serviced by one satellite at a time.<br>
</blockquote>
Are we sure here? One (classic) Dishy is served by one satellite at
a time, but a cell (which can contain multiple DIshys) almost has to
be serviced by multiple sats to get around obstruction issues
(Starlink is now quite tolerant of these. Try to put it in a tight
spot where it can't see the northern sky at your place in LA and
tell me whether it still connects. If it does, then your cell gets
served by multiple sats). <br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
>>> But now you want to serve cellphones on the ground
which have smaller <br>
>>> antennas by a factor of I'd say about 16:1
aperture-wise. So you need to <br>
>>> make your antennas in space 16 times larger just to
maintain what you had <br>
>>> with Dishy.<br>
>> <br>
>> the cell service is not intended to compete with the
Dishy, just be an <br>
>> emergancy contact capability<br>
><br>
> Here's how one of the local partner organisation here spins
it. Much more <br>
> than just an emergency contact capability:<br>
><br>
> <a href="https://one.nz/why-choose-us/spacex" moz-do-not-send="true">https://one.nz/why-choose-us/spacex/</a><br>
><br>
> (Judge for yourself whether this instils the impression that
you're going to <br>
> get 5G level service off this. You really need to read the
small print!)<br>
<br>
yeah, that does seem to imply more than it can offer. Elon has
been pretty vocal <br>
that each cell is something like 70 miles in diameter, and the
available <br>
bandwidth needs to be shared across all users. Text messages
should always work, <br>
voice will probably work, and as the system gets built out, data
will happen, <br>
but will be slow due to the sharing.<br>
</blockquote>
Yep, that's what I'd expect also. <br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
> It's not that easy. Adding satellites in the first instance
is just adding <br>
> transmitters, and unless you have spectrum to accommodate
these, then even if <br>
> the satellites' on-board bandwidth is higher, it doesn't
translate into as <br>
> much extra capacity. Spectrum comes in terms of extra Hertz,
and in terms of <br>
> spatial beam separation. The former is limited in that they
don't make any <br>
> more of it, and the latter is a matter of antenna size and
getting antenna <br>
> side lobes sufficiently far down. And we know that SpaceX are
running close <br>
> to spectral capacity in some areas.<br>
<br>
I am assuming that the fact that they have planned for 10x
satellites (~45k <br>
satellites up from the ~5k they have now) means that they have a
plan to be able <br>
to use that many efficiently. I have no inside knowlege, so I am
speculating <br>
about this.<br>
</blockquote>
<p>A lot of what is meant to go up there is meant to use higher
bands, which means "more bandwidth" but with caveats relating to
obstruction by atmospheric phenomena. So that wouldn't quite scale
I guess.<br>
</p>
<p>There are also other reasons for why you'd want more birds: </p>
<ul>
<li>Path diversity on ISLs to avoid "busy center" issues</li>
<li>Having each satellite look after fewer users on the ground
allows for more bandwidth per user overall due to spatial
diversity. </li>
<li> Better illumination of the ground.</li>
<li>Higher capacity in equatorial areas (where GSO protection
takes a good chunk out of what's directly overhead).</li>
<li>Redundancy.</li>
</ul>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
> Assuming that the spatial distribution of the under-connected
is somewhat <br>
> similar to Starlink's current customer base in terms of
densities, we need <br>
> that factor of 1000.<br>
<br>
I think there are a lot of early adopters for who Starlink is a
luxury, not a <br>
lifeline. </blockquote>
I think we're well past that point here. Last year's cyclone was the
best sales push Elon could have hoped for. You no longer get a
discount here for living rurally like last year. But you can get
deprioritised service.<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">I think
the under-connected are going to be in more sparse areas than <br>
the early adopters. I have friends and family in rural areas, and
awareness of <br>
Starlink is only slowly penetrating there.<br>
</blockquote>
The slow penetration of modernity into US rural areas seems to be a
particularly American problem - it's not been an issue here or in
the Pacific.<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
I'm seeing increased use for mobile applications here in the US,
including in <br>
built-up areas.<br>
</blockquote>
Interesting.<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
<br>
> So which factor in terms of capacity growth should we expect
of Starlink & Co <br>
> over today?<br>
<br>
not enough information. I agree it's something to watch, I'm just
more <br>
optomistic about it than you are.<br>
</blockquote>
OK, let's see how this pans out.<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
>>> And then you need to provision some to compete with
extra capacity you <br>
>>> wanted, and then some to cope with general growth in
demand per client. <br>
>>> And then you have to transmit that same viral cat
video over and over <br>
>>> again through the same pipe, too.<br>
>> <br>
>> True, although if you can setup a community gateway of
some sort to share <br>
>> one satellite connection, you gain efficiency (less
housekeeping overhead <br>
>> or unused upload timeslots), and have a place that you
can implement <br>
>> caches.<br>
><br>
> Indeed. Or if you provide a feed to a local ISP. But Starlink
still focuses <br>
> on direct to site, as does every other LEO provider FAIK.<br>
<br>
SpaceX is diversifying thier offerings, including boats, planes,
and very <br>
high-performance community gateways.<br>
</blockquote>
The latter run under "business" here and the data rates they talk
about aren't all that appealing given that this is what I see on a
roaming subscription already. But who knows!<br>
<blockquote type="cite" cite="mid:30p29846-8p5p-6134-r48o-1qr7o3n324p2@ynat.uz">
<br>
I'd love to see more tech folks supporting this sort of thing.<br>
<br>
I would especially like to see us put together disaster kits that
can take one <br>
uplink and spread it around. We've seen SpaceX being willing to
donate dishy <br>
kits, but being able to spread the hotspot island out from direct
wifi range of <br>
the dishy to be able to cover a larger area would be worth quite a
bit (and <br>
don't forget the need for power for the system)<br>
</blockquote>
<p>Yes - that's a lesson that's been learned here. <br>
</p>
<p>After last year's cyclone, a lot of local civil defence posts and
marae here have acquired Starlink kits and generators (NB: marae
are compound facilities operating as a focal point for indigenous
Māori life. Most are capable of housing and feeding large groups
of people at relatively short notice, and they are almost
everywhere. Often used for conferences, retreats, weddings,
funerals, public meetings, and not just by Māori).</p>
<p>One of the problems with disaster kits is their power use. Dishy
uses between 40 and 100W when "idle" with a laptop connected via
Ethernet, but uses noticeably more power (up to around 150 W on RX
and slightly less on TX) when receiving significant data volumes,
most likely due to the complex DSP needed to decode from the
phased array. <br>
</p>
<p>Half that and you could power it off a car cigarette lighter
socket with some ease. Would be interesting to hear how the latest
generation Dishy stacks up there. Oleg - have you measured?<br>
</p>
--
<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>
****************************************************************
</pre>
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