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charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Starlink] apnic piece on starlink X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Apr 2023 11:48:49 -0000 On 8/04/2023 12:10 am, David Lang wrote: > I will note that in the Starlink plans, there are plans > to put a layer of satellites at a sigificantly lower altitude. I should add to this that this would seem like a good strategy, except=20 of course that this comes with its own set of challenges. Earth=20 observation satellites in particular are abundant in lower orbits - if=20 you have a camera on board, you want to be as close to your subject as=20 you can. So there isn't quite as much space down there as there is=20 further up. Residual atmospheric drag at lower altitudes is also higher, which means=20 you either need to take more fuel to compensate (=3Dheavier satellite &=20 fewer sats per launch) or you need to replace the satellites more often. You also need more satellites for global coverage in a shell like this. Also, as you mostly look at satellites sideways when you're a ground=20 station, the path length and therefore the path loss isn't necessarily=20 all that much lower - going from 550 km to 275 km gives you an extra 6=20 dB of gain if the satellite is straight overhead, but that advantage=20 shrinks as you move away from zenith. > > By launching 10x as many satellites, and each one being able to handle=20 > 10x the > data, they _may_ get to 100x, but that is really going to be pushing=20 > it. (note > that this is for ~10x the number of satellites lauched by everyone=20 > other than > SpaceX since Sputnik) Having seen figures of ~45k sats bandied around for some proposed=20 mega-constellations, the 10x number of satellites might just work out.=20 Whether we'll get to 10x the capacity per satellite is another question=20 altogether given spectral constraints. With ISLs, one could in principle=20 free up part of the gateway traffic spectrum by putting gateways in=20 areas that are devoid of other users, but quite how practical that is=20 given that remote areas are where LEOs will be needed most is a good=20 question. One option that could push things a little further in conjunction with=20 LEOs would be HAPS=C2=A0 - high altitude platform systems, essentially=20 solar-powered UAVs that act as stratospheric cell towers with tours of=20 duty measured in weeks or months. These could use lasers as backhaul to=20 LEO networks, yet project comparatively narrow phased array beams to=20 users on the ground. A HAPS flying at 30 km overhead has a path loss=20 that's around 25 dB below that of a LEO sat at 550 km, and a clear=20 optical path to the satellites above. Technology isn't quite there yet -=20 essentially, we're at the point where solar cells have become performant=20 enough in conjunction with batteries that have become light enough to=20 allow sustainable cyclic recharging of a UAV's flight systems. But there=20 are still issues to be addressed around the excess power required to=20 operate a cell site in the sky and or course all the regulatory and=20 safety aspects associated with operating things that don't burn up when=20 they come down. > > If you can get fiber, it's always going to be better than a wireless=20 > option, DSL > is threatened by Starlink in many suburbs, cablemodems depend so much=20 > on the ISP > it's hard to say This is an interesting comment. Completely agree on the fibre aspect. DSL I think is threatened more by fibre than Starlink in most places=20 (except the US perhaps), which has basically displaced most DSL=20 connections where it became available. We were on DSL here till 2017,=20 and as fibre was on the horizon for a while, the company that runs the=20 cable network here on behalf of the telcos stopped investing in new=20 DSLAM modules, instead preferring to switch customers with problematic=20 ones to modules that had become available as a result of customers=20 migrating to fibre. We found ourselves with a weird problem literally=20 overnight one day - intermittent disconnects lasting a minute or two.=20 These persisted through a change of DSL router, and logging these for a=20 few days showed a clear diurnal peak time pattern - so it was obvious we=20 were dealing with DSLAM-side crosstalk issues here. I asked to be=20 switched to a different DSLAM. This was an odyssee of support calls=20 given that you cannot call the lines folk directly - you must call your=20 retail ISP, who pays someone in India a few rupees to tell you to reboot=20 your router to make the problem go away. By the time I'd educated their=20 3rd tier support about what crosstalk was, I'd literally spent many many=20 hours on the phone to India. Eventually, they switched me over to a new=20 DSLAM and the problem went away for a few months, just to return as they=20 kept rewiring more legacy customers. For those who still have DSL now, VDSL plans start at less than half of=20 what Starlink charges, with potentially comparable data rates, so not=20 everyone will want to switch. Where I see uptake of Starlink in urban areas here is by (a) geeks and=20 (b) folk who want a (secondary) connection that is independent of local=20 telcos that run inane call centres in India. The lines company that did=20 / does most of the fibre install here was a bit overwhelmed at the time,=20 so brought crews in from all over the place, as far afield as Zimbabwe.=20 Installation standards for fibre required them to bury 30 cm (12") deep=20 and dig under garden walls and hedges, however the crews got paid per=20 install, and a lot of the time, the standards were interpreted rather=20 liberally. Our crew arrived anticipating a two hour install and left=20 after eight hour and more "no-you're-not-going-to-do-it-like-that's"=20 than I care to count. A colleague of mine observed them laying through=20 his garden my just brushing the leaves aside. Around Auckland suburbia,=20 there are countless examples of fibre conduit running over posh volcanic=20 rock garden walls, through hedges, or along the top of rickety fences. Cable TV and cable modems are of course pretty much unheard of here -=20 are there any cable modems / ISPs that do more than a few dozen Mb/s down? > > David Lang > > _______________________________________________ > Starlink mailing list > Starlink@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink > --=20 **************************************************************** Dr. Ulrich Speidel School of Computer Science Room 303S.594 (City Campus) The University of Auckland u.speidel@auckland.ac.nz http://www.cs.auckland.ac.nz/~ulrich/ ****************************************************************