Comment by walrus01 | Hacker News Reader

Comment by walrus01 | Hacker News Reader

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> Actually, GEO satellites have quite a bit of aggregate capacity (1 Tbps and going up) and more capacity where it matters (over land, and specifically, population centers) than LEO constellations, and therefore have better bandwidth economics. They also last ~3x as long, which brings the $/Mbps down more.

the aggregate capacity of a 180 million dollar (construction plus launch cost) 6000 kg geostationary telecom satellite is less than two strands of fiber and a set of modern 100/200/400GbE coherent DWDM system line terminals.

saying that the throughput of all of the ka-band spot beams on a satellite is 1Tbps is both double-counting math for the capacity in both directions, and does not reflect the actual capability of the satellite. maybe if every single ground station was something large enough and with enough link budget to operate at 16APSK and better modulations. not a realistic figure if you're talking about low-cost, sub $1500 hardware, consumer grade ku and ka band vsats.

for a randomly chosen rural zip code in WA state, hughesnet is offering a 50GB quota/month for $150/month. so yes, 60GB transfer limits and things are still a real thing. and during peak evening hours TDMA contention means that latency will be 1150ms+, or worse.

the unavoidable economics of consumer grade small VSAT require serious oversubscription. Dedicated 1:1 satellite capacity starts from $1500/Mbps and up, and requires a serious VSAT terminal, not a hughesnet/viasat/wildblue type toy.

as to your last paragraph, if you have a proper 4G/LTE network in your area, just use that. There's verizon and at&t resellers with plans available that have quotas close to 200GB/month for a reasonable price now. why you would want a hybrid cheap vsat and 4G LTE setup, as a consumer, I don't know.

> the aggregate capacity of a 180 million dollar (construction plus launch cost) 6000 kg geostationary telecom satellite is less than two strands of fiber and a set of modern 100/200/400GbE coherent DWDM system line terminals.

Not sure how that's relevant. In any case, the total cost of a GEO is closer to double that.

> saying that the throughput of all of the ka-band spot beams on a satellite is 1Tbps is both double-counting math for the capacity in both directions, and does not reflect the actual capability of the satellite.

This is not correct.

> maybe if every single ground station was something large enough and with enough link budget to operate at 16APSK and better modulations. not a realistic figure if you're talking about low-cost, sub $1500 hardware, consumer grade ku and ka band vsats.

I'm not sure if you're talking about the ground stations that connect to fiber backhaul, here, or to the CPE terminals. In any case, ground station capacity is not an issue, and neither is CPE terminal capacity.

> for a randomly chosen rural zip code in WA state, hughesnet is offering a 50GB quota/month for $150/month. so yes, 60GB transfer limits and things are still a real thing. and during peak evening hours TDMA contention means that latency will be 1150ms+, or worse.

Yup, that's what I said: "... unless you're still using HughesNet."

> the unavoidable economics of consumer grade small VSAT require serious oversubscription. Dedicated 1:1 satellite capacity starts from $1500/Mbps and up, and requires a serious VSAT terminal, not a hughesnet/viasat/wildblue type toy.

Again, not sure how this is relevant. Every residential (and even many business) connectivity option is oversubscribed.

If you're saying that satellite cannot compete with fiber or cable, then you'd get no argument from me. If you're saying that satellite is a shitty option, well, I think you'd find that some people disagree with you on that.

That's not to say there isn't room for improvement, but providers know this and are working on it.

> In any case, ground station capacity is not an issue, and neither is CPE terminal capacity.

because consumer grade CPE terminals need to be so small (because of hardware cost and economics), link budgets suck and less complex modulations must be used. As compared to serious 1.8 meter and larger VSATs. Show me a consumer grade VSAT that's using 16APSK/32APSK and the correspondingly higher bps/Hz efficiency that can be achieved with big, expensive satellite earth station gear used for dedicated 1:1 links.

the aggregate throughput of a geostationary satellite is greatly reduced if you start using tons of tiny VSATs on it. Go look at how much actual capacity is available in a 15 MHz chunk of Ku transponder capacity (even with a 51dBm EIRP hot spot beam), used with an iDirect evolution series linecard at the hub end, that is populated by a bunch of cheap 1.2 meter compression molded fiberglass dishes with 3W/4W class BUCs on them. How many Mbps is that? Not a lot.

> Every residential (and even many business) connectivity option is oversubscribed.

the aggregate throughput capacity of a single CMTS port on a DOCSIS3 or DOCSIS3.1 network segment is equivalent to a significant portion of the entire capacity of a geostationary satellite serving consumers. one CMTS port can serve hundreds of (yes, oversubscribed) 200 to 1000 Mbps class residential end users. One 10GbE circuit feeding a 2U rackmount sized GPON OLT can serve a ridiculous number of end user customers. It's oversubscribed but not in such a way that individual users see latency increases during peak hours (unless somebody has really fucked up their network). With the CMTS example we're talking about things that regularly achieve 1024QAM to 4096QAM modulation on copper wireline plant using the RF channels that previously would have been analog TV.

wireline is oversubscribed? yes. I could show you traffic charts from a 175-suite condominium building where every unit is wired with symmetric gigabit 1000BaseT to the home, that has an 80% take rate of subscribers. The whole building has a single 10GbE uplink and everyone is perfectly happy. Because of course not everyone tries to use the whole capacity of anything all the time. But when you start getting into the wildly high oversubscription ratios needed to make geostationary consumer grade VSAT stuff work economically, it becomes a very poor end user experience.

> If you're saying that satellite is a shitty option, well, I think you'd find that some people disagree with you on that.

I'm saying geostationary consumer grade satellite stuff is a shitty option and should always be the choice of last resort when anything else exists, due to its unavoidable poor economics and aggregate capacity.

I have a lot more optimism that starlink will have the real world throughput needed to be a viable option for rural broadband. Because the link budgets are much better with small antennas and small tx poweer electronics, due to the LEO orbit. And the much lower latency. I think people who believe starlink will replace their 800 Mbps comcast DOCSIS3 32x8 connection or GPON last mile gigabit connection are not fully informed. Properly implemented wireline networks will always have a great deal more throughput at a much lower deployment cost. What Starlink will kill is crappy consumer grade VSATs and sub-75Mbps class terrestrial PtMP WISPs.

> Show me a consumer grade VSAT that's using 16APSK/32APSK...

Not that it matters, but, I could.

> How many Mbps is that? Not a lot.

So, e.g., Viasat offers 100 Mbps service.

> the aggregate throughput capacity of a single CMTS port on a DOCSIS3 or DOCSIS3.1...

Yes, you can get tons of traffic through a coax cable. There's more bandwidth and you can use higher efficiency modulations because the SINR is way better. Not sure how this is relevant, though.

I'll point out, though, that plenty of people see slowdowns on their cable modem networks during peak busy times. Even these networks have their limits.

> ... it becomes a very poor end user experience.

Again, I think some people would disagree with you on that.

> ... real world throughput needed to be a viable option for rural broadband. Because the link budgets are much better with small antennas and small tx poweer electronics, due to the LEO orbit. And the much lower latency.

No doubt about the lower power electronics (vis-a-vis GEO) and the lower latency, but even so, SL's CPE is around $1,000, and the reliability through rain, wind, and snow is unknown. Setting aside the reliability question for now, I think what it really comes down to is the price vs latency trade-off. In order to be profitable, SL will have to be more expensive than traditional GEO solutions because the CPE, the ground network, and the actual constellation all cost more on a $/bit basis than GEO solutions. It will be interesting to see if the lower latency will be enough to draw consumers.

The big X-Factor in all of this is how much more capital Elon can raise. He has an amazing talent for raising money and if retail investors don't care that SL is less cost-effective than other options, then it can go on for a long time.

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