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SpaceX, T-Mobile to connect satellites to cellphones in remote areas
321–330 of 496 posts
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#322While I see the great potential in this technology, the collateral damage is the loss of places where one can truly disconnect. I just got back from 4 days camping at a remote mountain lake with zero phone coverage, and it’s one of the most incredible ways to fully recharge and step away from the day to day treadmill of the modern world. When we loose the possibility to completely disconnect, I at least, will feel a…
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Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#323Earlier quoted context omitted.
I'm not sure what software was present on this random Lyft I took a couple months ago, but I was seated in the front, watching Tesla's infotainment screen the entire ride, which on one side was displaying a sort of wireframe (not the right word, but they weren't realistic drawings) of objects in front of and around the car as we were driving. I was alarmed to see how often pedestrians, and even cars passing while wai…
That sounds like it was probably the standard Tesla display, rather than the FSD Beta display? My understanding is that it's a very different system. But yeah, the standard display has pretty laughable object persistence.
I was interested in FSD but autopilot is so shitty and unreliable it has convinced me to not buy the upgrade. If they want to sell an expensive upgrade from autopilot to FSD they need to make the autopilot flawless at its job.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#324More 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…
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I'm also pretty out of date, but I believe in LTE (4G) the max distance was closer to 100km, with the timing advance controlled in the radio protocol.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 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.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#325I believe this is SpaceX trying to stay one step ahead of Apple. Anyone else remember this strange rumor about iPhones including satellite capability a year ago? https://www.macrumors.com/2021/08/29/iphone-13-to-feature-le... Now you have Apple’s event in a couple weeks themed “Far Out” with space pictures. I wouldn’t be surprised at all if Apple announced something similar, possibly with Globalstar instead. Of cours…
Today's announcement says my existing T-Mobile phone already had satellite capability!! They just need to get the satellites up.
It's not the first time I hear about this tech. AST SpaceMobile[0] wants to do exactly the same with existing 4G/5G phones.
Of course, they are launching with SpaceX. They might get sherlocked before even finishing their product.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#326More 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…
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'd think that the distance limit for _terrestrial_ mobile networks comes from the guard interval of the OFDM modulation [1]. I.e. on longer distances the time-offset between different different reception paths (due to reflections) of the signal becomes so long that you cannot compensate those with just a complex gain-factor of the OFDM vectors.
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 groundsatellite 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_...
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#327I 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.
After hyperloop and tesla semi, I don't trust Elon that much.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#328While I see the great potential in this technology, the collateral damage is the loss of places where one can truly disconnect. I just got back from 4 days camping at a remote mountain lake with zero phone coverage, and it’s one of the most incredible ways to fully recharge and step away from the day to day treadmill of the modern world. When we loose the possibility to completely disconnect, I at least, will feel a…
> the collateral damage is the loss of places where one can truly disconnect.
The real bummer is for the astrophotographers and observers who can’t do anything now without massive streaks of light flying everywhere.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#329Earlier quoted context omitted.
Why would large antennas require scrutiny by regulators?
A combination of orbital debris and astronomy issues. A big antenna means it's more likely to be hit by other satellites, and it'll be brighter. There's a good chance this might mean these are limited to the ~350 KM shells, which will deorbit faster (limiting debris risk), and will go into sunset sooner.
Is that an actual concern? Honestly sounds kinda nonsensical to me but I don't know enough about antenna size in orbit regulation.
Re: SpaceX, T-Mobile to connect satellites to cellphones in remote areas
#330Earlier quoted context omitted.
I think the "complicated antenna requirements" still exist - they've just put the complicated antenna on the satellite, instead of on the phone.
Yeah that's not how it works. You can't just "put the complicated antenna on the satellite, instead of on the phone" and declare this problem solved. If you believe that I have a bridge to sell you. I'm declaring shenanigans right now on Elon's pitch but what else is new. It makes me sad that this thread is full of (probably) SWEs in a complete froth who took this at face value with little understanding of how antenn…
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 in the next couple of months. Looks like a pretty complicated phased array antenna:
https://forum.nasaspaceflight.com/index.php?topic=50349.msg2...