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    <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">
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                                  <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>
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      <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">
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                                          <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>
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              <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>_______________________________________________
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</pre>
            </blockquote>
          </div>
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        </blockquote>
      </div>
      <br>
      <fieldset class="moz-mime-attachment-header"></fieldset>
      <pre class="moz-quote-pre" wrap="">_______________________________________________
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</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>
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