So are they looking at it from the mobile wireless perspective, where speeds are aspirational, “up to”, or “on a good day”? Or from the home Internet perspective, where people run speedtests and bitch if they don’t get what they’re paying for?
Who has ever gotten a refund or cancelled a 12 month contract on a cellphone because the speed didn’t match the marketing? And of course with any new service, whether it’s satellite or 5G, the early adopters will probably get fantastic speeds because there’s nobody else on the network. Let’s face it, WISPs do this too. Who hasn’t had a new WISP pop up in your area advertising speeds that sound like every subscriber gets the full capacity of the AP at max modulation. And how many reviews do you see that say the WISP was fast at first and then the speeds just got slower and slower. From: AF <af-boun...@af.afmug.com> On Behalf Of Adam Moffett Sent: Wednesday, July 15, 2020 1:42 PM To: af@af.afmug.com Subject: Re: [AFMUG] OT: Details on the Starlink router The FCC allowed them 2Ghz of bandwidth for the satellite to user terminal. 20Gbps must assume 10 bits/hz. Or maybe they mean a different sense of "capacity". The journalistic sources are never precise about these things. I've been assuming that just like any other wireless you can't put the same channel into the exact same location at the same time, or else they would interfere. So they might simplify and say "20 Gbps per satellite", but I think it's really going to be "20Gbps for a given geographic area". I don't know how big that area will be, but the smaller the satellite is, the smaller the antenna has to be, and then of course the wider the beam is. I imagine each satellite won't use the full 2ghz, but maybe dozens of satellites over a certain area will each use their own non-interfering chunk. ....I'll freely admit that I'm filling in blanks left by the articles I've seen. Maybe there are additional details to explain how they're solving these problems, but I suspect the 20Gb per satellite is not going to be meaningful. It'll be 20Gb total for a region of some size. On 7/15/2020 1:32 PM, Colin Stanners wrote: Doing some math: 40K subscribers on 60 satellites is 666 subs/satellite if equally loaded. But load is far from equal, the planet surface is 70% water. I don't know how much the "standard" orbit is over water but let's say 50% as it's further from the poles. Say that at any point in time, around half the satellites will be barely useful (except for cruise ships, and overseas aircraft service) due to being over water and ground obstructions. So a more accurate number is 1300 subs/well-positioned satellite, assuming for simplicity that subs are equally physically spread out. The numbers that I saw state that every satellite has 20Gbps capacity, let's assume that that is downlink subscriber capacity at maximum modulation, and that the backhaul to the ground station is fully available to that satellite and also 20Gbps at max modulation. 20Gbps / 1300 subs is 15mbit per sub, assuming that everyone's using it simultaneously. But there are the issues with wireless in general, added to those about customer self-installs (shudder), and satellite service: mainly subs having trees or obstructions in the way, blocking or reducing LoS to at least part of the sky where their hand-off satellite should be, and rain. I'd say that altogether that a more realistic number with those is 8-12mbit per user. Being generous, 12Mbit average per sub: not bad these days, considering the traffic patterns at peak time (1/3rd subscribers using Netflix / D+ / etc with 1-3 streams at HD or 4K) I'd assume that from that they could sell mostly 30-70mbit download speed plans without too much consternation. But as traffic keeps increasing, over time they may run out of capacity for the higher plans and decide to reduce. On Wed, Jul 15, 2020 at 11:58 AM Bill Prince <part15...@gmail.com <mailto:part15...@gmail.com> > wrote: There are some details in this story that were new to me. One of the ones that popped up was that each group of 60 Starlink satellites is expected to support ~~ 40,000 subscribers. That puts the 800 satellite "moderate service level" at supporting about half a million subscribers (~~ 533,000). In order to support a million subscribers, they will need about 1500 satellites. https://www.tesmanian.com/blogs/tesmanian-blog/starlink-router-fcc?_pos=19 <https://www.tesmanian.com/blogs/tesmanian-blog/starlink-router-fcc?_pos=19&_sid=a6c7fff07&_ss=r> &_sid=a6c7fff07&_ss=r -- bp <part15sbs{at}gmail{dot}com> -- AF mailing list AF@af.afmug.com <mailto:AF@af.afmug.com> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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