[Starlink] Starlink Roaming

Tue Feb 22 02:58:45 EST 2022

Perhaps worth remembering that they don't have to engineer the final 
system right now. Consider that:

- Building ground station gateways costs money, but as the number of 
subscribers grows, so does the income stream that allows for ground 
station construction.
- 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.
- 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
- Constellations that are short of capacity can be added to 
incrementally. Remember Starlink is at a very early stage of what 
they're planning.
- 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.

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.

On 22/02/2022 8:20 pm, Dick Roy wrote:
>
> ------------------------------------------------------------------------
>
> *From:*Starlink [mailto:starlink-bounces at lists.bufferbloat.net] *On 
> Behalf Of *Mike Puchol
> *Sent:* Monday, February 21, 2022 9:35 PM
> *To:* Daniel AJ Sokolov; David Lang
> *Cc:* starlink at lists.bufferbloat.net
> *Subject:* Re: [Starlink] Starlink Roaming
>
> 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.
>
> 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.).
>
> */[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/**/J/**/)/*
>
>
>
> Eventually they will go for optical gateways, it’s the only way to get 
> enough capacity to the constellation, specially the 30k satellite version.
>
> */[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./*
>
>
> Best,
>
> Mike
>
> On Feb 22, 2022, 05:17 +0300, David Lang <david at lang.hm>, wrote:
>
> On Mon, 21 Feb 2022, Daniel AJ Sokolov wrote:
>
> On 2022-02-21 at 13:52, David Lang wrote:
>
>
> They told me that I could try it, and it may work, may be degraded a
> bit, or may not work at all. They do plan to add roaming capabilities in
> the future (my guess is that the laser satellites will enable a lot more
> flexibility)
>
>
> Isn't that a very optimistic assessment? :-)
>
> Laser links are great for remote locations with very few users, but how
> could they relieve overbooking of Starlink in areas with too many users?
>
> The laser links can reduce the required density of ground stations, but
> they don't add capacity to the network. Any ground station not built
> thanks to laser links adds load to other ground stations - and, maybe
> more importantly, adds load to the satellite that does eventually
> connect to a ground station.
>
> Can laser links really help on a large scale, or are they just a small
> help here and there?
>
>
> My thinking is that the laser links will make it possible to route the 
> traffic
> from wherever I am to the appropriate ground station that I'm 
> registered with as
> opposed to the current bent-pipe approach where, if I move to far from my
> registered location, I need to talk to a different ground station.
>
> Currently there are two limits in any area for coverage:
>
> 1. satellite bandwidth
> 2. ground station bandwidth
>
> laser links will significantly reduce the effect of the second one.
>
> We know that they can do mobile dishes (they are testing it currently 
> on Elon's
> gulfstream, FAR more mobile that I will ever be :-) )
>
> David Lang
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-- 
****************************************************************
Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel at auckland.ac.nz  
http://www.cs.auckland.ac.nz/~ulrich/
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