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

https://youtu.be/Qzli-Ww26Qs?t=851

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 limits of what the tech will allow. Since they're advertising compatibility with existing hardware, makes me suspect there is an extension somewhere in the standards that allows the timing window to be increased, or maybe there's some clever hackery going on, like only scheduling every other timing window and cutting bandwidth in half.

Which might work on the uplink, but on the downlink I think it's more complicated to support something like paging, where the UE is mostly idle, and only wakes up occasionally, that things don't get out of sync with the moving satellite.

AFAIR LTE (4G) even uses different guard intervals depending on rural vs. city setting because that time-offset is larger in rural areas (less base station density).

I would not expect those problems to be relevant for satellite communication as ground<->satellite does not suffer much of the multi-path signal propagation of terrestrial systems. (IIRC DVB-c sat-TV broadcasts did not even use OFDM, at least not for the older "v1" DVB-c standard).

[1] https://en.wikipedia.org/wiki/Orthogonal_frequency-division_...

However 3G and onwards were based on CDMA tech (which was the competing 2G tech to GSM), which is very different. CDMA doesn't have strictly managed cells, but rather the basestation picks the signals out of a cacaphony (very simplified). So the same issue doesn't apply.

2G was much more static than CDMA, it had a strict capacity of a number of calls per cell. But the range (up to this 30km) was pretty good because when a phone transmitted the air was clear. CDMA cells used to 'breathe': Have much lower reach during busy times (because weak signals could no longer be identified) so gaps could drop in the network. ON the other hand, 2G got busy with a fixed capacity.

2G did have prioritisation though when the network was full. If you called 112 (the international emergency number) it would kick someone else off to make space for you.

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.

If you're a firefighter trying to call for assistance from base camp, you don't care about net neutrality. You want your emergency phone call to have priority over everything else. You want the net to be extremely non-neutral.

On the general internet, where bandwidth is plentiful, net neutrality can keep certain pathological things from being a thing. On a specialized network where bandwidth is very scarce, it can be the cause of pathology.

My biggest question is how do you send a signal to a satellite with your mobile phone. And they're even saying without additional hardware which makes it even more difficult.

Or are they just hoping that there would be no obstructions from your device and the satellite, no roof and a good sunny weather?

Although my knowledge is lacking, my understanding is that 2G has good range at the expense of low data rate. But I have a feeling that many modern phones no longer support 2G, since (at least here in Slovenia, Europe) many providers have over the years lowered or totally removed the number of 2G towers.

End game will be their own private networks but that's still a while away

This is Apple we are talking about. They wouldn’t make this play without some form of vendor lock-in. They will probably choose to lock in based on hardware (“must have iPhone 14 for this capability!”) — but I wouldn’t be surprised to see them lock in on the software side as well.

If I were Tim Cook, I might play both sides. “Bandwidth is limited, so for now, this will only work with iMessage.” This gives them room to open it up later for more good PR, and allows them to test the reaction of having it only work with their proprietary software.

I have no insider knowledge here. I follow this space closely due to co-owning an independent repair business that primarily works on Apple products.

T-mobile has 110 million subscribers and the population of USA is 329 million people.

Of course, they are launching with SpaceX. They might get sherlocked before even finishing their product.

[0] https://ast-science.com/spacemobile/

5 years from now you'll be choosing a particular android or apple phone because its good for satellite, just like you choose a particular one today because it's small, or fast, or has a good camera

So baseline, a modern cell phone can connect to a tower about 45 miles away. Stsrlink satellites orbir about 10 times out from that. They are solving this problem by some very clever phased array technology to be deployed on the satellites themselves, because when it comes to radio, you can often solve the problem of signal reception by boosting either the transmitter or the receiver side of the story.

This is how we've kept in touch with the Voyagers all this time. The Voyager radio technology is getting no better, but the technology we can throw at it from a ground station has been out-stripping the loss due to distance and degradation (or at least approximately keeping pace).

Starlink satellites are about 330km up, so one order of magnitude further. But they also have basically unobstructed line of sight (if you are under blue sky). Compared to the normal conditions a cell phone has to deal with that might get you a substantial improvement. I think it's plausible that at least some existing phones can do it, with the tiny bandwidth you would expect from a poor signal.

This is extremely low bandwidth and intended for sending extremely high latency text chats. Elon said in the presentation that it could be as much as 30 mins between hitting send and the message going through.

This competes with existing stuff from existing satellite providers.

It’s really really cool, and doesn’t need to be full on smartphone satellite internet to fulfill that coolness!

That's because it's an app that connects to an Iridium phone via BT.

I can't find anything suggesting a bundling or partnership between garmin inreach (iridium) and T-mobile. inReach has a separate subscription.

SpaceX will need to get FCC/ITU approval for the G2 satellites. T-Mobile is seeking agreements with international carriers. I think those are probably required for the proposed system to be viable. Spectrum management bureaucracies in other countries, and opposition from competitors will slow things down. It will require a lot of money to get worldwide operating agreements in place, and some of the money will be bribes to the right people.

Expected by whom? People who didn't understand the problem presumably.

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.

As for SpaceX, their reputation for getting things done is rock solid right now. If they manage to get starship going, that will be a major leap in launching capabilities. But even just getting the star link network operational, or delivering people to the space station have been enormous accomplishments already.

The only thing that's remarkable about this announcement is how unremarkable it is relative to Elon Musk's other accomplishments. It's a radio on a satellite that connects to a phone. Doesn't sound like rocket science. I'm sure the antennas etc. are amazing but that is essentially commodity technology that he's simply launching to orbit. Doing that cheap enough that stuff like this makes sense to even consider doing is the true accomplishment.

I know the meme is that Musk's track record is to delay, but Starlink has been regularly underestimated and has kept pace pretty successfully. Much more than industry insiders expected.

Leave your SIM card home

That's a human problem with a human - not technical - solution. You need to find a way to resist temptation. I promise you'll be better for it in more areas than you realize.

I hear you on offline maps though. Back in the day I paid the Tom Tom tax when going to Europe because $100 for offline maps was ultimately better than trying to figure out a roaming plan or local sim.

“Sorry I was on a plane then”. “You texted me right as I was checking into hotel- got distracted while replying and forgot to send”. “Couldn’t answer the phone - was at a restaurant and answering the phone is rude”.

Didn’t take long before the lies became true and I would forget to reply when I see the message.

You have the power to make it your reality. If the issue is replying to people, give yourself small permissions to not be punctual. If someone dies, you’ll still know immediately… but that work memo may have arrived why you were on a plane ;). If your issue is that you can’t stop scrolling through twitter or HN then i don’t know. Take more exciting vacations? Rarely when I travel would I rather be scrolling endlessly (except maybe while in line places).

So we should all be denied a new potentially life-saving technology, because of your own self control issues?

Also, take the SIM out (assuming you don't use an ESIM), give it to your spouse or put it at the bottom of your backpack as others suggested, or leave it at home/in your car. Emergency calls will still work.

It's the amateurs who are screwed.

For example, Iridium only got GMDSS/SOLAS certified in 2020 – before that, Inmarsat was the only approved maritime (two-way) satellite safety provider for several decades.

If space based cellular service is viable with good adoption. History says operators will want at least two providers because having only one vendor is risky.

Adding things like mesh networks, you could drop a small server rack and generator at any where in the world and create a robust cell network to cover disaster zones.

You are tracked on your phone because it is connected to the Internet somehow, so it can send your location. But with only a GPS receiver (my Garmin running watch for instance), you are completely invisible.

can anyone disclaim this? What are the anechoics of an airplane mode phone?