<!DOCTYPE html><html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<p>Yep. Getting 17 Mb/s from a single satellite to a single
cellphone is one thing. But serving multiple/many users is a
different story. Because if that's what you want to do, you only
have a few options:</p>
<ul>
<li>Share the beam capacity between them - everyone gets a slice.</li>
<li>Have more (and smaller) beams, so the same frequency can be
used in parallel for multiple users. This requires more and
larger antennas on the satellite. <br>
</li>
<li>Up EIRP to get more power down to Earth. This requires larger
antennas on the satellite.</li>
</ul>
<p>As a general rule, when it comes to having sharp beams, both
antenna gain (for a fixed size antenna) and path loss between
spacecraft and ground increase with the square of the carrier
frequency. Antenna gain helps us to get a nice signal at the
receiver, path loss works against us in this sense. We have one
antenna at each end - and gains multiply - so that gives us a term
that's proportional to frequency to the power of 4. Divide that by
the frequency to the power of 2 from your path loss and you end up
with a signal at the receiver that is proportional to the
frequency squared. What does this mean in practice? Well, it means
it's easier to project sharp beams if your carrier frequency is
higher. <br>
</p>
<p>Now for the D2D phone spectrum that SpaceX are using, we're
between 1 and 2 GHz. The Ku and Ka spectrum band that Starlink is
otherwise licensed for is between 10 and 30 GHz. That's very much
back foot territory for the D2D beams compared to the Ku and Ka
ones.</p>
<p>So low bit rate D2D services with few users are a much easier
target to hit than 4G data rates for the rural populus at large.<br>
</p>
<div class="moz-cite-prefix">On 4/06/2024 11:54 pm, Frantisek Borsik
via Starlink wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAJUtOOhviNUkkuUsmCSqMNuqLuDqGAyJaMWBFDaSZwpx26pOuA@mail.gmail.com">
<div dir="ltr">The whole article is worth reading, but tl;dr;
<div><br>
</div>
<div>
<p id="ember21385" class="ember-view gmail-reader-content-blocks__paragraph" style="box-sizing:inherit;margin:1.6rem 0px;line-height:1.75;color:rgba(0,0,0,0.9);font-family:-apple-system,system-ui,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","Fira Sans",Ubuntu,Oxygen,"Oxygen Sans",Cantarell,"Droid Sans","Apple Color Emoji","Segoe UI Emoji","Segoe UI Emoji","Segoe UI Symbol","Lucida Grande",Helvetica,Arial,sans-serif">"The
promise of D2D is alluring – that we can be connected
wherever we are – no more not-spots and the certainty of
always being able to contact others. But the reality is some
way from this. The only existing D2D service is Apple’s
iPhone emergency communications which offers messaging to
the emergency services and vehicle assistance in 16
countries. This does not appear to be a service Apple thinks
it can charge for at present.</p>
<p id="ember21386" class="ember-view gmail-reader-content-blocks__paragraph" style="box-sizing:inherit;margin:1.6rem 0px;line-height:1.75;color:rgba(0,0,0,0.9);font-family:-apple-system,system-ui,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","Fira Sans",Ubuntu,Oxygen,"Oxygen Sans",Cantarell,"Droid Sans","Apple Color Emoji","Segoe UI Emoji","Segoe UI Emoji","Segoe UI Symbol","Lucida Grande",Helvetica,Arial,sans-serif">Those
offerings that have the greatest potential for ubiquity are
within the MSS spectrum. But here bandwidths are too
constrained to deliver full service capabilities. Other MSS
operators such as Iridium have struggled to put together a
commercial D2D proposition (although their core business
remains strong).</p>
<p id="ember21387" class="ember-view gmail-reader-content-blocks__paragraph" style="box-sizing:inherit;margin:1.6rem 0px;line-height:1.75;color:rgba(0,0,0,0.9);font-family:-apple-system,system-ui,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","Fira Sans",Ubuntu,Oxygen,"Oxygen Sans",Cantarell,"Droid Sans","Apple Color Emoji","Segoe UI Emoji","Segoe UI Emoji","Segoe UI Symbol","Lucida Grande",Helvetica,Arial,sans-serif">The
other approach of using MS spectrum has strong backers in
the form of SpaceX and T-Mobile as well as multiple
promising start-ups. But it is beset with challenges of
avoiding interference with existing terrestrial use,
overcoming restrictions in border areas, ensuring compliance
with hundreds of regulators, of which only one has a defined
policy towards D2D at present, doing deals with hundreds of
operators and managing other regulatory hurdles. Only
US-based coverage looks likely any time soon and the true
extent of that remains unclear.</p>
<p id="ember21388" class="ember-view gmail-reader-content-blocks__paragraph" style="box-sizing:inherit;margin:1.6rem 0px;line-height:1.75;color:rgba(0,0,0,0.9);font-family:-apple-system,system-ui,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","Fira Sans",Ubuntu,Oxygen,"Oxygen Sans",Cantarell,"Droid Sans","Apple Color Emoji","Segoe UI Emoji","Segoe UI Emoji","Segoe UI Symbol","Lucida Grande",Helvetica,Arial,sans-serif">With
limited offers, the consumer interest will be less. Quite
how much less is very unclear, but it is clear that the
business case will be challenging. Most consumers appear to
have limited interest in paying more per month for better
coverage.</p>
<p id="ember21389" class="ember-view gmail-reader-content-blocks__paragraph" style="box-sizing:inherit;margin:1.6rem 0px;line-height:1.75;color:rgba(0,0,0,0.9);font-family:-apple-system,system-ui,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue","Fira Sans",Ubuntu,Oxygen,"Oxygen Sans",Cantarell,"Droid Sans","Apple Color Emoji","Segoe UI Emoji","Segoe UI Emoji","Segoe UI Symbol","Lucida Grande",Helvetica,Arial,sans-serif">In
summary, D2D’s alluring promise of ubiquitous fully-featured
global connectivity is not likely to be realised any time
soon, if ever, but a reduced service level in a few
countries may be sufficient to justify launching suitable
satellites."</p>
<br class="gmail-Apple-interchange-newline" style="color:rgb(0,0,0)">
<br class="gmail-Apple-interchange-newline">
<div>
<div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div>All the best,</div>
<div><br>
</div>
<div>
<p class="MsoNormal" style="color:rgb(34,34,34)">Frank</p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Frantisek
(Frank) Borsik</p>
<p class="MsoNormal" style="color:rgb(34,34,34)"> </p>
<p class="MsoNormal" style="color:rgb(34,34,34)"><a href="https://www.linkedin.com/in/frantisekborsik" style="color:rgb(17,85,204)" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://www.linkedin.com/in/frantisekborsik</a></p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Signal,
Telegram, WhatsApp: +421919416714 </p>
<p class="MsoNormal" style="color:rgb(34,34,34)">iMessage,
mobile: +420775230885</p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Skype:
casioa5302ca</p>
<p class="MsoNormal" style="color:rgb(34,34,34)"><a href="mailto:frantisek.borsik@gmail.com" style="color:rgb(17,85,204)" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">frantisek.borsik@gmail.com</a></p>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jun 4, 2024 at 1:43 PM
Alexandre Petrescu via Starlink <<a href="mailto:starlink@lists.bufferbloat.net" moz-do-not-send="true" class="moz-txt-link-freetext">starlink@lists.bufferbloat.net</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
<div>
<p><font size="2" face="Courier New">does it say whether it
is text only, data only, or everything including voice?</font><br>
</p>
<div>Le 04/06/2024 à 13:20, Frantisek Borsik via Starlink a
écrit :<br>
</div>
<blockquote type="cite">
<div dir="ltr">Some additional reading from William Webb:
<div><br>
</div>
<div><a href="https://www.linkedin.com/pulse/satellite-direct-device-workable-william-webb-sonke/?trackingId=Sjha4DY8SqONFA9g%2Bb5b%2Bw%3D%3D" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://www.linkedin.com/pulse/satellite-direct-device-workable-william-webb-sonke/?trackingId=Sjha4DY8SqONFA9g%2Bb5b%2Bw%3D%3D</a></div>
<div><br clear="all">
<div>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div dir="ltr">
<div>All the best,</div>
<div><br>
</div>
<div>
<p class="MsoNormal" style="color:rgb(34,34,34)">Frank</p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Frantisek (Frank) Borsik</p>
<p class="MsoNormal" style="color:rgb(34,34,34)"> </p>
<p class="MsoNormal" style="color:rgb(34,34,34)"><a href="https://www.linkedin.com/in/frantisekborsik" style="color:rgb(17,85,204)" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://www.linkedin.com/in/frantisekborsik</a></p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Signal, Telegram, WhatsApp: +421919416714 </p>
<p class="MsoNormal" style="color:rgb(34,34,34)">iMessage, mobile: +420775230885</p>
<p class="MsoNormal" style="color:rgb(34,34,34)">Skype: casioa5302ca</p>
<p class="MsoNormal" style="color:rgb(34,34,34)"><a href="mailto:frantisek.borsik@gmail.com" style="color:rgb(17,85,204)" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">frantisek.borsik@gmail.com</a></p>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jun 4, 2024 at
2:54 AM David Lang <<a href="mailto:david@lang.hm" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">david@lang.hm</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Eugene
Y Chang wrote:<br>
<br>
>> On Jun 3, 2024, at 12:41 PM, David Lang <<a href="mailto:david@lang.hm" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">david@lang.hm</a>>
wrote:<br>
>><br>
>> Eugene Y Chang wrote:<br>
>><br>
>>> I expect low data rate because the
distance will fall back to a lower coding rate.<br>
>><br>
>> I think it's going to be more a matter of
very large cells, so many people sharing the available
bandwidth<br>
>><br>
>>> I observe a difference in my phone’s
batter life between urban and rural usage. I expect
the battery life to be significantly reduced with
Starlink.<br>
>>> And yes… if the phone isn’t communicating
then the battery life isn’t drawn down much…<br>
>><br>
>> In my experience, a phone that's trying to
find a tower uses more power than one that has a
tower, but is otherwise idle<br>
><br>
> When the phone is searching for a tower, it is
transmitting at maximum power.<br>
> Then, the phone adjusts the transmit power
according to the distance to the tower,<br>
> In an urban environment, the distance to the
tower is usually less (i.e. smaller cells due to
subscriber density).<br>
> In a rural environment, there is more distance to
the tower, and the phone is transmitting at higher
power (i.e., towers are farther apart for larger cells
due to fewer subscribers per tower, up to the max
tower separation.)<br>
> When you are mobile, the power is proportionate
to the mean distance to the tower during your
operations.<br>
<br>
and for direct-to-satellite, it's going to be a max
power situation, similar to <br>
rural.<br>
<br>
But when a phone is not connected, how frequent are
it's searches for towers <br>
(especially if it has multiple bands to check)
compared to the 'keepalive' pings <br>
when it is connected? if it's doing more transmissions
for it's search and <br>
attempts to connect than it does while connected and
just confirming the <br>
connection, that could eat more power.<br>
<br>
David Lang</blockquote>
</div>
<br>
<fieldset></fieldset>
<pre>_______________________________________________
Starlink mailing list
<a href="mailto:Starlink@lists.bufferbloat.net" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">Starlink@lists.bufferbloat.net</a>
<a href="https://lists.bufferbloat.net/listinfo/starlink" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.bufferbloat.net/listinfo/starlink</a>
</pre>
</blockquote>
</div>
_______________________________________________<br>
Starlink mailing list<br>
<a href="mailto:Starlink@lists.bufferbloat.net" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">Starlink@lists.bufferbloat.net</a><br>
<a href="https://lists.bufferbloat.net/listinfo/starlink" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.bufferbloat.net/listinfo/starlink</a><br>
</blockquote>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
Starlink mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Starlink@lists.bufferbloat.net">Starlink@lists.bufferbloat.net</a>
<a class="moz-txt-link-freetext" href="https://lists.bufferbloat.net/listinfo/starlink">https://lists.bufferbloat.net/listinfo/starlink</a>
</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
****************************************************************
Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
Ph: (+64-9)-373-7599 ext. 85282
The University of Auckland
<a class="moz-txt-link-abbreviated" href="mailto:ulrich@cs.auckland.ac.nz">ulrich@cs.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>
</body>
</html>