Satellites Are Becoming the New Cellphone Towers

https://spectrum.ieee.org/satellite-cellphone-starlink

by frasermarlow • 2 years ago

132 176 2 years ago

spectrum.ieee.org

Larger antennas and better beamforming are routing calls through orbit

akira25012• 2 years ago

Calls have been routed through orbit from handheld devices for decades now. Ironically, Iridium used SpaceX to launch one of their recent LEO constellations.

This seems to be strictly about high data rate applications and the certainly soon to be extremely goofy world of "6G."

lxgr14• 2 years ago

Not yet. For now, "direct-to-cell" and its competitors are all about text/voice/low-data-rate applications in areas that so far haven't had any coverage at all, given the extremely low signal strength involved due to the extreme distances, low transmission powers, and omnidirectional device antennas.

kelnos3• 2 years ago

Sure, but not through a standard cellular phone, or with a standard cellular phone's small, hidden antenna, or with a standard cellular phone's battery.

aaron695• 2 years ago

AST SpaceMobile’s first satellites had antennas with surface areas of 64 square meters

Pic- https://spacenews.com/ast-spacemobile-secures-communications...

Pic from earth - https://twitter.com/tzukran/status/1731409049004982558

cubefox• 2 years ago

And their ambitions are even higher...

For example, AST SpaceMobile’s first satellites had antennas with surface areas of 64 square meters, followed by second generation satellites with 128 m2 antennas, with plans for going up to 400 m2

I guess when the Starship rocket is available and if they have a reliable folding mechanism, this could happen. The question is probably whether they can keep the cost under control .

dheera• 2 years ago

I certainly hope we don't rely only on satellites, in case of a solar flare that destroys all the satellites.

blackoil• 2 years ago

Satellite can't beat bandwidth or latency of a cell tower in neighborhood connected to fiber connected to edge node few km away.

guappa• 2 years ago

But most people don't know that. Not yet at least.

looofooo02• 2 years ago

Yet, https://physicsworld.com/a/alpine-adaptive-optics-experiment....

kube-system2• 2 years ago

No but theoretical round-trip times are getting pretty dang short as these sats are launched into lower and lower orbits.

The round-trip speed of light to a geosync orbit is 239ms, but some of these LEO sats are already sitting as close as a 4ms round-trip away, and there have been proposals for some even closer.

AnarchismIsCool4• 2 years ago

Yeah, I think the market they're ultimately going for here is to stop having to roll out cell towers to areas where there's low population density, like rural areas, the mountain west, stuff like that. In cities, it'll always be more efficient for any given set of EM spectrum technologies to use small installed antennas within a few 100m of you than it'll be to push the same link over 500km.

firecall• 2 years ago

Having zero knowledge, I'm curious:

Would a Solar Flare wrap around the earth?

Or are Solar Flares so massive they would envelop the earth, like dunking a globe in cosmic lava?

Or do they go on long enough that the earth would rotate and all sides of the globe would be exposed?

Or do Satellites whizz around the earth fast enough that they would travel through the path of the Solar Flare?

Probably hilariously odd questions, but I have no idea! :-)

teeray• 2 years ago

Maybe the carriers’ marketing departments will hand out little 4 bar stickers to put in the upper corners of your phone while they loudly proclaim “full bars everywhere!” Of course, conveniently continuing to ignore latency in the mobile core, which is what increasingly impacts end user quality of service more than “bars.”

lxgr14• 2 years ago

These satellites are around 500 km up. Round-trip latency is less than 10 ms if you’re somewhat close to a ground station, and if you’re not, odds are you’re not that close to your application server either and would have comparable latency in fiber.

phildenhoff• 2 years ago

I never before considered that "the edge" may become a constellation of Starlink satellites. Round-trip latency is a lot better if your messages are only going 500km.

That said — can you imagine deploying your service to ~5200 satellites? yikes

vsnf• 2 years ago

I was recently in a country that strictly controls internet communications. Like, total lockdown absolutely forbidden levels of control. I spent my time there constantly wondering about the inevitable advent of ubiquitous wireless communication via things like Starlink and what the effects would be on these totalitarian regimes.

Edit: I didn't mean to focus on Starlink specifically. Eventually it won't just be Starlink up there, and likely our mobile devices will need less and less power to communicate with those satellites. So I'm less interested in the effects of Starlink and more on satellite communications generally.

looofooo02• 2 years ago

You can have Starlink in Iran already, but neither in Russia or China.

baxtr• 2 years ago

What is the reason for that?

lxgr14• 2 years ago

Assuming Starlink is really willing to violate local frequency licensing requirements (which I doubt they'd dare for all but the most internationally isolated countries without anti-satellite weapons), given the low transmit powers, local wireless jammers should be relatively easy to implement.

dkbrk• 2 years ago

given the low transmit powers, local wireless jammers should be relatively easy to implement.

Not true. Both the transmitter and receiver (in both directions) utilize phased arrays. This means the receiver is very good at rejecting noise angularly separated from the expected location of the transmitter. Geometry dictates that jamming could be somewhat effective against upload (i.e. if the jammer is located roughly within the size of a spot beam from the transmitting dish), but is almost completely ineffective in the download direction.

This is all fairly theoretical since much of the details aren't publicly available; but as evidence I point to the fact that Russia has poured a huge amount of money into EW and, despite having considerable motivation to deny Starlink access, has consistently failed to prevent its widespread use by Ukrainian troops on frontlines mere kilometers from its own forces.

Kluggy• 2 years ago

Starlink blocks access to specific countries that it doesn't have approval to work in, so I presume they'll just be blocked while the totalitarian regimes are in power.

system2• 2 years ago

What can they do if Starlink doesn't obey them? Shoot them down with rockets?

londons_explore2• 2 years ago

I don't think this is the case. They don't sell hardware/service in countries they don't have approval to operate in, but their global roam service operates in places they don't have an operation license for, which is why south Africa is pissed off [1]

[1] https://www.itweb.co.za/article/icasa-takes-note-of-illegal-...

mytailorisrich2• 2 years ago

I doubt satellites will be competing with land-based networks in general because they can't deliver the same throughput, latency, and capacity.

In addition, as others have mentioned, companies do not like to take on whole countries unless perhaps it is a very small and irrelevant one.

hyperthesis• 2 years ago

Starlink would have that control.

infinet• 2 years ago

I have lost hope that human can fight totalitarianism, regardless the new technology been used. It is like the low energy state of society, similar to a ball tends roll down the hill, it is easier for a country to enter the totalitarian state and stays there than to get out of it by itself. Imagine a North Korean owns a such cell phone, according to rumors, it is a crime if the spouse, children, or neighbors don’t report to the authorities. Governments can also jam communication, just like they jam radio programs and censor Internet. A more likely scenario would be regimes use new technology, including direct cell phone to satellite communication, to monitor and control people.

ulf-77723• 2 years ago

Interesting Read! How will this change influence companies like American Tower? How fast will they need to adapt? 5 years, 10 years, 20 years?

joecool10294• 2 years ago

I doubt Crown Castle and American Tower will be much affected, it might reduce some new rural deployments, but other contracts like Firstnet also increased requirements for rural buildout, so it's not going away. Indoors isn't going to be covered by satellite beams.

greatNespresso• 2 years ago

Something I have wondered about is how can a layman like me could communicate with a satellite? I would need an antenna of some sort I believe but then what's the protocol?

lxgr14• 2 years ago

Depends entirely on what you want to do!

There are amateur radio satellites that you can legally communicate with using a technician’s license and equipment for around $100 (essentially a UHF/VHF FM walkie-talkie and an external antenna, i.e. just analog voice).

If you have a fairly modern iPhone, you can already share your location to a satellite out of the box.

And if unidirectional communication counts, you already do it every time you use GPS :)

katbyte5• 2 years ago

But a garmin inreach mini, pair your phone, and then start texting people via it’s app :)

numpad0• 2 years ago

IIRC there are some open packet data protocol intended as cost saving measures, but nothing mandatory or ubiquitous as Ethernet or RS-232C in PCs. A primer/tutorial level for hobbyist satellite communication is weather satellite reception using RTL-SDR.

1: https://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-noaa-weat...

ianburrell• 2 years ago

There are amateur radio satellites. You would need to get your amateur radio license, although you can listen without it. Then you need handheld radio. Two, or more expensive dual band, if want to transmit. It is possible to use the builtin antenna. But lots of people use directional Yagi antennas, you can build cheap one.

Most of satellites you don’t talk to, the satellite repeats signals. People talk to each other, mainly to make contacts, using the satellite.

It is also possible to talk to ISS.

CraigJPerry2• 2 years ago

It’s hard to bet against human determination but on the face of it, it seems out of reach to put satellite voice calls in a package the size of an iPhone.

The power requirements and thus the bulky batteries of existing satellite phones could be reduced by switching to protocols which trade off bandwidth for higher error correction abilities through encoding and I don’t think existing satellite phones use the most bandwidth efficient encoding available so that could be another improvement.

There’s still the free space path loss between the surface of earth and a Globalstar or Starlink which my best guess estimate is in the order of 130db (can anyone more knowledgeable share a better estimate? I assumed bottom end of L-band, a height between Starlink and Globalstar, and used unverified dBi values for antennas at both ends).

Then there’s latency but I don’t think that’s a show stopper for many common use cases of voice and data.

lxgr14• 2 years ago

The power requirements and thus the bulky batteries of existing satellite phones could be reduced by switching to protocols which trade off bandwidth for higher error correction abilities

No, you can’t trade bandwidth against error correction. What you can do is use channel coding/error correction to trade effective signal-to-noise strength against data rate (at constant power).

But since your data rate demand is fixed for voice, and the uplink transmit power is fixed too (by 4G/5G specs), you need to raise the received signal strength. The only thing that can help you there are more directional receive antennas on the satellites, which is what these new generations are doing.

AnarchismIsCool4• 2 years ago

To be clear, what's happening here is people are accustomed to using "bandwidth" to mean bits/second but bandwidth has a much more specific meaning in the RF world, akin to calling Ethernet "SSH".

Bandwidth is the actual number of kilo/mega/gigahertz the signal occupies on the spectrum and is largely a function of symbol rate, but the actual data rate has many more variables.

livueta2• 2 years ago

You can talk to satellites over lora with a 5w transceiver (source: done it), which is on the order of magnitude of a cell phone transceiver. Opus goes down to .75kbps. Ham boomerisms don't cleanly apply to modern voice codecs and digital modulation techniques.

wkat42428• 2 years ago

How do you do LoRa over a sat? I thought the chirping makes that difficult because you exceed the passband on the sat? Interesting! Which sat did you use?

katbyte5• 2 years ago

I would be quite happy with texting or very slow internet tbh

pasquino• 2 years ago

Why you should if you don't have to ? Satellite phones are a thing at least since the 90s, but nowadays you prefer some kind of communication via Internet, possibly using wifi. Ok, emergency call, place out the civilisation, but those are same use case present 30 years ago. If you don't have to you want to use real cell towers or wifi. Also I think that to cover the communication needs of a single western rich country they have to increase the number of satellite drastically, with lot of side effects. So really satellites aren't new cell towers. Besides, is that type of infrastructure so profitable to justify its creation ? I want to say, if I wasn't able to do an emergency call the problem was dead battery, not absence of signal, in other cases I use the ol' dirty Marconi's wireless telegraph: the radio. Obviously , if I have a way to send sms from desert place, it's a "nice to have feature" not a necessity for the majority of us, so, again , how the company want to monetise from the infrastructure that is greatly expensive ?

ale422• 2 years ago

Totally agree with your point of view.

Another thing to consider is how much the bands dedicated to cell phones are already saturated in dense urban environments. I don't see how a few thousands satellites would be able to scale if they were to replace our actual cell towers (some of them consisting of local cells on utility poles, etc.).

And also, satellites dedicated to search and rescue to locate emergency beacons already exist, and you don't need many of them to cover the whole planet.

Animats• 2 years ago

Another thing to consider is how much the bands dedicated to cell phones are already saturated in dense urban environments.

That's what 5G is supposed to be for. In dense areas, there are supposed to be a large number of tiny cells operating in the 5GHz-6GHz range. The main application for this is stadiums, so the fans can be getting video on their phone while watching, or not watching, the dame. Most of the NFL stadiums now have this.

Other parts of cities, not so much yet.

katbyte5• 2 years ago

I essentially pay a bunch of money to garmin so i can text people while camping and offroading and send tiny amounts of data to update my position on a map.

I got a iPhone 14 for a backup satellite sos method.

In Canada there are 100s of km of roads between towns with zero cellphone service, often for hours at a time. Having space based communication in a cellphone to fall back on would be extreme valuable and life saving to many. I know I already pay a bundle for it and many of my outdoorsy friends do the same. I can be driving to a friends house a few hours away and be out of signal for half of it, being able to call for help if I encounter or get into an accident is pretty important and building cell towers would be far more expensive then some satellites

Aerbil3132• 2 years ago

and building cell towers would be far more expensive then some satellites

Historic.

user_78322• 2 years ago

send tiny amounts of data to update my position on a map

If you could clarify- is this data like mobile data/internet, or data in a literal sense? Because if you’re SMSing your GPS coordinates to a friend’s phone you could stick to only SMS.

wkat42428• 2 years ago

I wouldn't call it "The new cellphone towers" as if satellite service will replace ground based. Because it won't.

Starlink direct to cell will still cover huge areas per cell which is great for remote areas but not for high density like cities. It will not have strong enough signals to penetrate buildings. And it won't provide enough bandwidth for more than texts at least not for now.

It's an augmentation of the land based service, not a replacement.

vmfunction• 2 years ago

And it won't provide enough bandwidth for more than texts at least not for now. So are we back to 14k modem speed for Satellites data now?

Hopefully this will bring back website that is focus being on being lightweight, and just display information (or gemini type of alternative), and discourage the SPA development fiasco that has happened.

kelnos3• 2 years ago

SPAs should/could in general be more tolerant of restricted bandwidth, and more responsive in that environment.

If you download all the UI elements, layout, and styling up-front, and then only have to communicate with the server to fetch structured data that tells the app how to change the user interface, that's strictly better.

The issue, of course, is that most pages (regardless of whether they're SPAs or not) require a large amount of bandwidth to download assets.

But I would expect that a low-bandwidth SPA would be more responsive than a traditional low-bandwidth website where it has to reload the full page every time you do something.

addandsubtract• 2 years ago

Or we just preload jQuery onto phones and go back to the CDN days :P

wkat42428• 2 years ago

So are we back to 14k modem speed for Satellites data now?

Not 'back'. This is normal for satellite data other than static Starlink installs with their huge antenna. The iridium Go! Hotspot does about 2400 bps :) they also have a new note expensive version that does up to 88 kbps download and 22 up. Still dialup speed so?

mytailorisrich2• 2 years ago

When satellites first appeared the future was going to be satellites. It turned out that the future was land-based optic fibres because of thoughput, latency, and capacity.

Jemm• 2 years ago

Likely won't work indoors where humans spend most of their time.

frasermarlow2• 2 years ago

It certainly won't work inside my 100 year old townhouse where my WiFi router signal can't reach from one floor to the next!

jMyles• 2 years ago

I don't love this model. It feels so censorable and state-adjacent. All states need to do is convince whoever controls the satellites to accept their terms. It's such a small number of points of failure.

The mesh model, where every rooftop is a node routing encrypted traffic to neighbors, feels much more sustainable / forward-looking to me.

Etheryte• 2 years ago

The mesh model is a nice idea, but does not work in low/no population areas, plus across long distances. Coincidentally that's exactly where satellites shine.

Satellites Are Becoming the New Cellphone Towers

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