FCC has “serious doubts” that SpaceX can deliver latencies under 100ms

There&#x27;s no doubt that this sort of technology can in principle deliver sub-100ms latencies. Take a look at my analysis here with inter-satellite links:<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=QEIUdMiColU" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=QEIUdMiColU</a><p>And here without ISLs:<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m05abdGSOxY" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m05abdGSOxY</a><p>Now, these videos assume no queuing delay. It&#x27;s really hard to guarantee low queuing delay in a traditional IP network, but there&#x27;s been a lot of research over the years, and we have a range of ideas that can be used to deliver minimal queuing with reasonable utilization. In fact doing this for Starlink is something I&#x27;m actively researching at the moment. I&#x27;m convinced it can be done, but it won&#x27;t look like a conventional IP network internally. I don&#x27;t know what SpaceX will actually do, so if the FCC has doubts, this is perhaps where they are concerned. Other delays might be in the ground segment, but that&#x27;s more or less the same for SpaceX&#x27;s terestrial competitors, and the FCC seems to think they can do it.

If my math is right geostationary satellites have a round-trip time (just at speed of light in a vacuum) of ~240 mS whie LEO satellites have a round-trip time of ~13 mS.<p>Current observed latency on geostationary satellite uplinks is 550 mS, presuming delays scale linearly with the travel time in vacuum that puts us at ~30 mS round-trip for LEO satellites.<p>Sub-100 mS seems physically possible to me but from an engineering and volume perspective there may be a real challenge.<p>Anyone with more knowledge care to chime in?

If you want a really great visualization and latency estimates for starlink check out the models and videos this guy came up with:<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=QEIUdMiColU" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=QEIUdMiColU</a><p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m05abdGSOxY" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=m05abdGSOxY</a><p>The comment from the FCC about it not accounting for &quot;processing [&amp;] routing&quot; is kindof nonsense on its face, those are not novel problems they&#x27;re already done by ever other router and switch, including several other satellite networks.

Generally there are four types of internet delay namely propagation delay, processing delay, queueing delay and transmission delay. For satellite link, regardless of Geo or Leo the propagation delay will be dominating the equations.<p>I believe Starlink&#x27;s engineers would have figured all the delay situations to claim less than 100ms latency and hopefully they will publish a credible white paper about it to refute FCC&#x27;s counter claim.<p>Elon if you&#x27;re reading this please send email to my username on Gmail for a third party verification of the latency, and of course with a small amount of fee in USD :-)

I remain sceptical for several reasons:<p>While these are early <i>alpha</i> at best, so is Starlink atm because it currently lacks the sat to sat laser comms.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Atmospheric_satellite" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Atmospheric_satellite</a><p>Furthermore there are<p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;ZBLAN" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;ZBLAN</a> and<p>[3] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Photonic-crystal_fiber" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Photonic-crystal_fiber</a><p>to be taken into account, which all have the potential to change the equations without spamming the skies, or at least less so.

The FCC is fairly conservative on what they believe can be delivered and rightly so. However this is the kind of technology that as taxpayers we should be funding. Things that are right at the envelope of possibility. It&#x27;s not impossible but highly complex and involves a ton of calculations. Sounds exactly the kind of problem that technology is good at solving.

It would be great if LEO could solve the rural broadband access problem, but why should taxpayer dollars be provided to companies that do not have a proven solution? Time after time various businesses such as Frontier have gamed the system without providing any value.

How about money back if they don&#x27;t deliver? Even better would be bounty <i>after</i> delivering the service, but I do see how it&#x27;s hard to combine that with the (reverse) auction mechanism.

I&#x27;m going to miss looking at the stars and not seeing satellites.

I suspect a large portion of this latency will arise from the use of error correcting codes, time division multiplexing, and utilization tricks (i.e. compression) employed on the RF uplink and downlink.<p>And that’s ignoring the queuing delay that anyone who is within three hours&#x2F;150 miles of a major city will experience. Users from the cities will choke the satellites.

This feels like FCC just making noise to prove that they won&#x27;t just grant it to SpaceX because they&#x27;re hot right now

Why the snarkiness from the FCC? They could have just said, &quot;you can have the funding if you can show low latency, please prove it to us&quot; -- end of story. It sort of reveals that they are already siding with &#x2F; super-chummy with &#x2F; in the pocket of the terrestrial ISPs, no?

It’s amazing to me that we allow a regulatory body the power to decide, before a system is even built, whether it qualifies as a “such-and-such performance” system. Why not just wait and see before potentially excluding LEO providers from certain spectrum auctions? Why? Hmmm... the idea of regulatory capture by incumbents provides one potential answer.<p>Then again what’s the risk? If the new folks meet the bar, you can always change the rules.

There is a subtext here that is not about the facts. Speculating, people influencing the FCC might be trying to reduce the availability of investment capital to SpaceX, and increase it to incumbents.<p>If I were an incumbent, I would be very worried indeed. If I supplied capital to incumbents, I would be demanding a greater risk premium, about now.

Why give money to unproven technology when we know ground networks work and can be low latency?<p>Surely there is a market for Starlink even without government funding. Then after they prove it is reliably low latency they can apply again. This isn&#x27;t DARPA it&#x27;s the FCC.