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A comment on SpaceX plans worldwide satellite Internet with low latency, gigabit speed. Parent comment

Re:SpaceX plans worldwide satellite Internet with low latenc... by Veratyr on Thursday November 17, 2016 @06:56PM (#12983030)
To take home users as an example, the residents generally sleep 8-10 hours a day, work 9 hours a day, commute ~1 hour a day, leaving only about 6 hours of free time at home a day. Assuming they spend that entire time watching 4K Netflix (25Mbit), they'll have used ~2TB in a month, or ~6Mbit/s total. Averaging bandwidth out over the whole month, each satellite would be able to support 3800 people. With the 4400 satellites they intend to deploy, they could support 16 million people.

Of course you generally need to provision for peak bandwidth rather than average so these numbers aren't even close to accurate but I think it's a rough explanation for why you don't need to fully provision every link.

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Re:SpaceX plans worldwide satellite Internet with low latenc... by damianknz on Thursday November 17, 2016 @08:43PM (#12983628)
But also bear in mind that the all the satellites over New Zealand (for example) will be wasted while we are asleep and at any given time a lot of satellites will be over empty ocean (sending 4K Netflix to cruise ships maybe).

I';; also counteract may own argument as to numbers with the idea that 16 million people could really mean 16 million households if they watch the movie together :-)

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Re:SpaceX plans worldwide satellite Internet with low latenc... by tim333 on Thursday November 17, 2016 @08:24PM (#12983543)
2TB/month is a lot. Home data caps tend to be more 10 - 40GB and I've got 4GB data on my phone which is fine for most stuff except video. I doubt the service will be very cheap - sat services are usually more than cellphone data.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by cortesoft on Thursday November 17, 2016 @07:39PM (#12983280)
Yeah, most people sleep at the same time.

Working for a CDN, we see our POPs gets about 4x traffic at peak compared to low times.

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Re:SpaceX plans worldwide satellite Internet with low latenc... by freehunter on Thursday November 17, 2016 @08:31PM (#12983577)
Most people sleep at the same time in one given geography, but if you're looking at the world, those times are pretty well distributed. Assuming I'm sleeping 8 hours a day, even the continental US only has 5 hours per day when everyone is asleep when you account for time zones. But APAC, ME/Africa, and Europe are all pretty reliably awake at that time.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by cortesoft on Thursday November 17, 2016 @11:13PM (#12984282)
Yeah, but that doesn't mean you can just put all the satellites right above the part of the world that is awake - so you are still going to not have a perfectly efficient system.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by oillio on Friday November 18, 2016 @01:54AM (#12984886)
Why not? I wonder if you could construct a polar orbit that followed the daylight around the earth. Add higher concentrations of satellites to the orbits that correspond to the higher traffic hours of the day.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by mnw21cam on Friday November 18, 2016 @04:43AM (#12985548)
Yes, it's called a sun-synchronous orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit

The exact orbit has to be arranged so that it precesses once a year, keeping it aligned with a particular local time of day. "Typical sun-synchronous orbits are about 600–800 km in altitude, with periods in the 96–100 minute range, and inclinations of around 98°"

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Re:SpaceX plans worldwide satellite Internet with low latenc... by Symmetry on Friday November 18, 2016 @09:45AM (#12987049)
There are 5 planes of 75 satellites planned by SpaceX later on for 81 degrees inclination which might be sun syncronous during the day but the initial 32 planes of 50 satellites are all headed for 53 degrees inclination which I'm sure isn't. You can't have sun synchronous orbits anyways for those satellites providing coverage during the night.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by mnw21cam on Friday November 18, 2016 @10:09AM (#12987226)
> You can't have sun synchronous orbits anyways for those satellites providing coverage during the night.

Um, what? Of course you can.

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Re:SpaceX plans worldwide satellite Internet with low latenc... by Symmetry on Friday November 18, 2016 @10:40AM (#12987465)
Well, I mean you can put a satellite in orbit so that it always goes over the equator at midnight local time. But then it's solar panels will never get any juice and it won't function.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by mnw21cam on Friday November 18, 2016 @10:45AM (#12987500)
If it's in a sun-synchronous orbit when it is crossing the equator at midnight local time, then it will also cross the equator at midday local time on the other side of the world.

We have weather satellites in this exact orbit right now.

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Re:SpaceX plans worldwide satellite Internet with low latenc... by Symmetry on Friday November 18, 2016 @11:51AM (#12988087)
You're right, my mistake.
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Re:SpaceX plans worldwide satellite Internet with low latenc... by ooqr on Saturday November 19, 2016 @11:20AM (#12994109)
Yet another reason to do away with DST
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