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SpaceX, T-Mobile to connect satellites to cellphones in remote areas

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Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#351

Post by WithinReason »

wongarsu wrote: post #76
nootropicat wrote: post #21

Earlier quoted context omitted.

What the... is that what's possible with 5G? Amazing, and even days ago I was thinking of satellite smartphone internet as something scifi because of (clearly incorrect!) complicated antenna requirements.

4G/LTE was commonly quoted as 3km range for rural installations (using the 2GHz bands). 5G added 700MHz and 800MHz bands that are quoted as 10-20km achievable range. For typical cell tower heights 20km is about the range where they would sink behind the horizon, so that might be the practical limit here. Starlink satellites are about 330km up, so one order of magnitude further. But they also have basically unobstruct…

Not to forget that satellite antennas are directional and can focus all their power in a narrower beam

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#352

Post by ars »

mlindner wrote: post #104
bombcar wrote: post #87

Earlier quoted context omitted.

If it’s send-only than a satellite receiving a ping isn’t insane - they’re only 340 miles up.

It's not send only. It's a standard cell phone service.

It's text and data only, no voice.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#353

Post by samatman »

pishpash wrote: post #312
samatman wrote: post #303

Earlier quoted context omitted.

Phased arrays are pretty cool, if I had no idea how they worked I'd be incredulous as well.

A phased array far away is effectively a point source.

Not when it's synthesized from numerous satellites.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#354

Post by comboy »

arbuge wrote: post #55

More detail here: https://www.cnbc.com/2022/08/25/spacex-and-t-mobile-team-up-... "T-Mobile users will be able to use messaging, MMS and certain messaging apps, from remote points across the lower 48 states, Alaska, Puerto Rico and Hawaii and even some remote points in the water. Eventually, the service will work with voice, Sievert said. T-Mobile plans to include the service in its most popular mobile plans but did…

> to transmit directly to a cell or mobile phone.

If it could talk directly with mobile phones it's a game changer.

But I don't understand how it could be physically possible without phased array and satellite tracking for a phone to transmit anything back to satellite. If achieved, even a few bytes per minute would already be big.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#355

Post by yaantc »

kevin_nisbet wrote: post #324
danellis wrote: post #280

Earlier quoted context omitted.

Interesting. Is there no distance limit? I don't know how 5G works, but in 2G there was a limit of about 30km, since that's as much as the timing advance would allow for (sending the signal early so that it arrives in its timeslot despite the speed-of-light delay).

I'm also pretty out of date, but I believe in LTE (4G) the max distance was closer to 100km, with the timing advance controlled in the radio protocol. As I understand it, the 5G radio protocol should be fairly similar to 4G, it wasn't completely reinvented for once. Based on my read of the summary of a couple Mbps per cell and focusing more on low bandwidth services like texting makes me suspect they're right at the…

Yes indeed, LTE max cell size is 100 km.

There's a system using LTE to backhaul Internet traffic from planes (WiFi in cabin, with a LTE to the ground), working with larger cells of up to ~900 km from memory, but it doesn't use standard LTE for example. It uses a modified variant made to support the possibly larger propagation delay coming with larger cells.

For 5G (NR), the max cell size has been increased and depends on the OFDM subcarrier spacing. For a 15 kHz SC, same as LTE, the max cell size is 300 km. This value is halved each time the SC doubles.

There's work on-going to extend NR to non-terrestrial networks. I don't know where it stands right now, but it'll likely add larger cells support. But it's not there yet for sure.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#356

Post by mhio »

assttoasstmgr wrote: post #336
mhio wrote: post #330

Earlier quoted context omitted.

This isn't a Starlink/SpaceX scheme. Non-terrestrial networks are being worked into the 3GPP specifications and highlight the same handset difficulties that need to be addressed. It's not the phone currently in your pocket that does this but might be fine on the phone you get in the next few years. https://www.3gpp.org/news-events/partners-news/2254-ntn_rel1... The BlueWalker 3 test satellite from AST should launch i…

> It's not the phone currently in your pocket that does this but might be fine on the phone you get in the next few years. I don't think anyone's questioning this - yet there's people here rage-posting the ludicrous assertion that the very handset in your pocket right now will work with Starlink unmodified. This is what I have an issue with. More FSD-style overpromising and underdelivering all over again.

They did go a bit hard on the existing phone's bit, tmobile guy at least used the word "aspiration" when mentioning it. I somehow doubt it, but maybe phone radio implementations are very forward looking on the standards?

In any case, late '23 never means '23. So maybe actual useful service in '25-'26 when the network, phones and sats are all ready.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#357

Post by solarkraft »

fragmede wrote: post #99
anonymousiam wrote: post #5

I watched the announcement. Knowing Musk, I'll believe it when I see it, but it sounds promising. Apparently the G2 Starlink satellites will be equipped with large antennas to support cellular users on the existing spectrum. Video was live-streamed, and still available here: https://www.youtube.com/watch?v=Qzli-Ww26Qs

Self-driving cars have proven harder than expected, but given the rest of Musk's tale, I wouldn't bet against him. SpaceX is already launching satellites, and Starlink is already providing service. T-mobile owns the frequencies for it, it's "just" a matter of building the satellites and putting them into space. If the claim were more outlandish, it would be harder to buy, but the technology is eminently doable.

Musk has had some failures (FSD, battery replacement, solar roof, satellite laser communication), but also notable successes (supercharger network, landing a rocket).

While this particular idea seems theoretically possible, as far as I know there haven't really been proper tests of it yet. So I could imagine it theoretically working, but being really bad (which may honestly be enough).

There's probably a reason Apple seems to be doing hardware adjustments for their satellite communication.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#358

Post by rvz »

MichaelCollins wrote: post #246
rvz wrote: post #177

Earlier quoted context omitted.

> I think you damage your own credibility more than Musk's by saying things like this. Why are you making it about this commenter? They are not wrong. Unless you can answer this next question: > He's delivered on electric cars and reusable rockets. It's fair to say promises more than he delivers, but he delivers an awful lot. So where are the 1 million robo-taxis driving around at Level 5 FSD ready for release in 202…

Ardent Musk critics look at FSD, see a scam, and conclude that Musk is a scammer and everything he does is a scam. Ardent Musk fanboys look at the rockets, see them actually work, and conclude that Musk is legit in everything he does. Personally I think Musk's ventures are a mix of scam and legitimate. His rockets are real, but I don't believe for a minute they'll ever send a colony to Mars. His cars are real, but an…

Well, my criticism is specifically and only with FSD.

There was no mention of me calling SpaceX, Tesla cars, etc a scam. You can support and purchase a Tesla but also be critical of the claims about FSD and leave out SpaceX, Starlink, etc.

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#359

Post by londons_explore »

Can they do that with existing T-Mobile's issued radio licenses?

If not, I assume there will be a ~1 year delay while the whole lot goes through FCC approvals and every competing company puts in complaints and lawsuits about how it's unfair...

Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas

#360

Post by lrvick »

adev_ wrote: post #349
lrvick wrote: post #344

Earlier quoted context omitted.

Certain messaging apps... All bets are on centralized and/or proprietary ones that can afford to pay for the privilege. I have been saying from day one that Starlink is well poised to end net neutrality.

> All bets are on centralized and/or proprietary ones that can afford to pay for the privilege Or not. App like Silence ( https://silence.im/ ) have been able to do secure e2e messaging using SMS as transport layer for almost one decade now.

SMS makes it very hard to be anonymous. Not a good option IMO.
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