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Tue, 27 Feb 2024 11:16:40 +1100 X-MC-Unique: cFWDcGqlOtGUY-_zZerNyQ-1 Received: from SY4PR01MB6979.ausprd01.prod.outlook.com (2603:10c6:10:142::13) by ME3PR01MB8373.ausprd01.prod.outlook.com (2603:10c6:220:18d::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7292.29; Tue, 27 Feb 2024 00:16:38 +0000 Received: from SY4PR01MB6979.ausprd01.prod.outlook.com ([fe80::2faf:5dbf:9124:8a6f]) by SY4PR01MB6979.ausprd01.prod.outlook.com ([fe80::2faf:5dbf:9124:8a6f%5]) with mapi id 15.20.7316.035; Tue, 27 Feb 2024 00:16:38 +0000 Message-ID: <857a228c-cf02-4a2c-98cb-771f71f070d0@auckland.ac.nz> Date: Tue, 27 Feb 2024 13:16:37 +1300 User-Agent: Mozilla Thunderbird To: David Lang Cc: starlink@lists.bufferbloat.net References: <28ro46p9-5620-9qr2-829q-3s0on13q6po6@ynat.uz> From: Ulrich Speidel In-Reply-To: <28ro46p9-5620-9qr2-829q-3s0on13q6po6@ynat.uz> X-ClientProxiedBy: SY5P282CA0129.AUSP282.PROD.OUTLOOK.COM (2603:10c6:10:209::11) To SY4PR01MB6979.ausprd01.prod.outlook.com (2603:10c6:10:142::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SY4PR01MB6979:EE_|ME3PR01MB8373:EE_ X-MS-Office365-Filtering-Correlation-Id: 15e93dab-c3fe-46f1-45dd-08dc37295db1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0 X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Starlink] Comprehensive Measurement Study on Starlink Performance Published 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: Tue, 27 Feb 2024 00:16:45 -0000 On 27/02/2024 12:19 pm, David Lang wrote: > On Tue, 27 Feb 2024, Ulrich Speidel via Starlink wrote: > >> My most serious concern about Starlink as a system remains the fact=20 >> that it puts a pipe between the end user and the first network hop=20 >> (the satellite) that is in principle very difficult to scale: There's=20 >> only so much extra spectrum one can use, spatial diversity=20 >> (beamforming) has limited potential, and unlike in cellular networks,=20 >> you can't really shrink the cell size to accommodate more end users=20 >> through frequency re-use as your cell size is determined to a good=20 >> part by orbital altitude. That all but rules out the scaling effects=20 >> that CDNs have brought to the rest of the Internet, which keep orders=20 >> of magnitude worth of traffic off long distance cables. There simply=20 >> isn't an obvious place in LEO topology to put a cache that'll produce=20 >> a decent number of hits while being able to serve this content to end=20 >> users through a large collective bandwidth. >> >> The interesting question for me is how much we can scale Starlink and=20 >> its up-and-coming cousins from the few million users Starlink has=20 >> now. To 100 million? To 200 million? Half a billion even? > > If you are in an area where the cell companies are investing in=20 > smaller cells, then you are not in a Starlink target area.=20 Hm. I'm in Auckland, which is where cell companies are investing in=20 smaller cells, and Starlink did a leaflet drop here last year trying to=20 get customers. > There are large areas with poor or non-existant cell coverage. > > Outside the US, scaling of Starlink can happen just by providing=20 > coverage to locations that don't yet have coverage with no additional=20 > satellites. But what's the population of these areas? Generally quite sparse. (Or=20 politically disinclined to accept Starlink service) > > In terms of scaling existing areas, larger antennas can reduce cell=20 > size, you can have more than one satellite cover a given cell, they=20 > are looking at eventually having lower satellites, which again will=20 > let them reduce the cell size. Lower orbit =3D more drag =3D shorter lifetime, and the reduction in=20 footprint isn't actually that significant. Larger antennas =3D fewer sats= =20 per launch =3D more expensive system. If you put in fibre today, you know that by upgrading the endpoints over=20 time, you can get orders of magnitude of extra bandwidth if needed. If=20 you can reduce distance between satellite and ground station by a factor=20 of 2, all else being equal, theoretically you'd also reduce footprint to=20 a quarter, but that's assuming you don't need to worry about antenna=20 sidelobes. But say we can, and then that gives us a factor of 4 in terms=20 of capacity as long as our user density is the same. It also buys us an=20 extra 6 dB in received signal power and hence an extra 2 bits per=20 symbol. That's another factor of 4 at best if you go from 1 to 3=20 bits/symbol. Larger antennas: Doubling antenna size gives you 3 dB in=20 gain or an extra bit per symbol. So that turns into a game of=20 diminishing margins pretty quickly, too. But now you want to serve=20 cellphones on the ground which have smaller antennas by a factor of I'd=20 say about 16:1 aperture-wise. So you need to make your antennas in space=20 16 times larger just to maintain what you had with Dishy. That's a far=20 cry from what is needed to get from two million or so customers to=20 supply two billion unconnected or under-connected. For that, we need a=20 factor of 1000. And then you need to provision some to compete with extra capacity you=20 wanted, and then some to cope with general growth in demand per client.=20 And then you have to transmit that same viral cat video over and over=20 again through the same pipe, too. --=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/ ****************************************************************