On Tue, 27 Feb 2024, Ulrich Speidel wrote:
On 27/02/2024 12:19 pm, David Lang wrote:
On Tue, 27 Feb 2024, Ulrich Speidel via Starlink wrote:
There are large areas with poor or non-existant cell coverage.
Outside the US, scaling of Starlink can happen just by providing coverage
to locations that don't yet have coverage with no additional satellites.
But what's the population of these areas? Generally quite sparse. (Or
politically disinclined to accept Starlink service)
per square mile? low. But there are a LOT of square miles, and those areas are
ones where it's very expensive per-user to run fiber (even to cell towers or
wireless ISP towers)
There are governments politically disinclined to allow cell service, not so much
the users. And some of the opposition is not opposition to Internet service, but
rather being protective of existing providers. Protectionism can be defeated in
time.
In terms of scaling existing areas, larger antennas can reduce cell size,
you can have more than one satellite cover a given cell, they are looking
at eventually having lower satellites, which again will let them reduce the
cell size.
Lower orbit = more drag = shorter lifetime, and the reduction in footprint
isn't actually that significant. Larger antennas = fewer sats per launch =
more expensive system.
and at the same time SpaceX is working to massivly reduce the launch costs.
If you put in fibre today, you know that by upgrading the endpoints over
time, you can get orders of magnitude of extra bandwidth if needed.
If you can get fibre, you should get fibre (with starlink as a possible backup).
SpaceX has said many times that Starlink is never going to be competitive to
fibre
if you can get fibre, you aren't under-connected.
If you can reduce distance between satellite and ground station by a factor of
2, all else being equal, theoretically you'd also reduce footprint to a
quarter, but that's assuming you don't need to worry about antenna sidelobes.
But say we can, and then that gives us a factor of 4 in terms of capacity as
long as our user density is the same. It also buys us an extra 6 dB in
received signal power and hence an extra 2 bits per symbol. That's another
factor of 4 at best if you go from 1 to 3 bits/symbol. Larger antennas:
Doubling antenna size gives you 3 dB in gain or an extra bit per symbol. So
that turns into a game of diminishing margins pretty quickly, too.
add in the ability for multiple satellites to serve a single cell and you can
get a noticable multiple as well
But now you want to serve cellphones on the ground which have smaller
antennas by a factor of I'd say about 16:1 aperture-wise. So you need to make
your antennas in space 16 times larger just to maintain what you had with
Dishy.
the cell service is not intended to compete with the Dishy, just be an emergancy
contact capability
That's a far cry from what is needed to get from two million or so customers
to supply two billion unconnected or under-connected. For that, we need a
factor of 1000.
without knowing what the user density of those under-connected are, it's going
to be really hard to get concrete arguments.
Spacex is intending to launch ~10x as many satellites as they have now, and the
full 'v2' satellites are supposed to be 10x the bandwidth of the V1s (don't know
how they compare to the v2 minis), that's a factor of 100x there. Is another 10x
in the under-served areas being in less dense areas really that hard to believe?
And Starlink will hopefully not be the only service, so it shouldn't have to
serve everyone.
And then you need to provision some to compete with extra capacity you
wanted, and then some to cope with general growth in demand per client. And
then you have to transmit that same viral cat video over and over again
through the same pipe, too.
True, although if you can setup a community gateway of some sort to share one
satellite connection, you gain efficiency (less housekeeping overhead or unused
upload timeslots), and have a place that you can implement caches.
David Lang
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