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Every story about SpaceX satellite Internet (Starlink) is plagued by questions about high latency. I think Elon needs to plan on spending a lot of marketing mo

Every story about SpaceX satellite Internet (Starlink) is plagued by questions about high latency. I think Elon needs to plan on spending a lot of marketing money to overcome this specific misconception. Starlink latency is quite good. LEO is a lot closer than GEO (less than ~1000 km* vs 35786 km.) SpaceX actually intends to compete with terrestrial systems on latency; many important routes will have significantly lower latency than any feasible terrestrial system. Remember, fiber isn't latency free. It isn't even speed of light. It's about 70% SOL. Radio, on the other hand, is SOL (or so close it doesn't matter.) So there is a cross over point where the latency of a LEO satellite system is actually superior despite the uplink/downlink path. *depending on which orbital "shell" is involved. figures range from 340 km to 1200 km.

stcredzero 8y ago
SpaceX actually intends to compete with terrestrial systems on latency; many routes will have significantly lower latency than any feasible terrestrial system. I would like to see a framework, where the backend of a cloud system can migrate opposite to the direction of orbit, so the same virtual cloud server could remain (by 'hops' where it serializes a copy of itself, then fails over to the copy) more or less geostationary. Such migrations would happen as seldom as once per 10 minutes. My game server cluster isn't too far away from having such a capability. (I was planning a variety of capabilities, such as using cheap GCP "ephemeral" instances by quickly failing over to such copies.)
- jtchang 8y ago
  This is basically vmware's vmotion feature.
  - stcredzero 8y ago
    That's quite cool. I'm doing my feature at more of an API level. That said, many applications still need to be architected to do this sort of migration well. The turnkey version just guarantees a demo version. (As technology develops, the turnkey capability will increase, but people's demands on the technology will also increase.)
- smachiz 8y ago
  Why would you need to do this? The constellation still needs downlinks - and the downlink nearest the physical location of the user should always be where that traffic pops back onto the Internet.
  - stcredzero 8y ago
    For a game server cluster, I would be running a game loop implemented as a series of pure function functor-like objects, located "very near" a spatial database. In that case, I would be migrating to provide the very lowest latency, as if the system were running on a "geostationary" server just a few hundred miles overhead. (Which has to pause for a quarter second, once every several minutes.)
    - imtringued 8y ago
      That sounds like a terrible experience. You want to avoid latency spikes at all costs. People might not like latencies as high as 100ms to 200ms but it definitively is possible to enjoy a laggy game like that. Suddenly getting a 500ms latency every minute will cause a lot of weird and unfair situations that can basically ruin the entire game.
      - chupasaurus 8y ago
        I agree, jitter bigger than a synchronization time is worse than high latency. When player have high latency (and I was in top3 on NA Solo ladder in League of Legends while playing from Urals with 220ms), he could only predict the moves of the opponent because what you see is far behind the server state, but with stable latency he knows the exact delay between an input and registering it on the server which puts less pressure to mind to deal with desynchronization between the picture on a display and the actual state.
        stcredzero 8y ago
        I agree, jitter bigger than a synchronization time is worse than high latency. I'll always grant that fast twitch FPS will always have a problem with this. That's not the genre I'm interested in creating games for, and it's not what my server framework is designed to support. (It is real-time action, but the pacing is more akin to RTS than FPS.)
- wbl 8y ago
  If only there was a large mass of rock and mud that was geostationary.
- TeMPOraL 8y ago
  Wait, what? Are you planning to put your game server in orbit? Because otherwise I don't understand what you're asking - a server on the ground will always be "geostationary" - it's the satellites it talks to that will change.
starpilot 8y ago
He's halving altitude to 550 km, in ideal cases bringing latency to 15 ms. Some satellites will be even lower, 350 km, for populated areas. https://arstechnica.com/tech-policy/2019/04/spacex-changes-broadband-satellite-plan-to-limit-debris-and-lower-latency/ https://arstechnica.com/tech-policy/2019/04/spacex-changes-b...
- jayess 8y ago
  I presume that's just one direction?
- RHSeeger 8y ago
  Is it 15ms to the satellite? If so, that's like 30ms to land, which would negatively impact gaming if it still needs to travel from where it lands to the end goal (via normal pathing?)
  - slenk 8y ago
    30ms is a good ping for games... edit - yeah I forgot about the endpoint then to the game servers data center
    - jalgos_eminator 8y ago
      The 30ms figure is just the earth->satellite->earth part though. It still has to go through terrestrial wires to the server, and then be processed, and back through wires to the transmitter.
      - imtringued 8y ago
        Datacenters make deals with network providers. Why should it be any different with Starlink?
    - earenndil 8y ago
      That's not 30ms ping, that's add 30ms ping.
shaklee3 8y ago
The high latency questions are only from people who really don't understand the industry. The question most analysts in the industry ask are about how they plan to be profitable.
- rurp 8y ago
  "People who don't understand the industry" describes nearly all potential customers. I don't think this refutes the GPs point.
  - jessriedel 8y ago
    Most potential customers don't know the difference between bandwidth and latency, they just think of it as speed.
    - shaklee3 8y ago
      I disagree. I think people equate bandwidth with speed, because that's what all of the commercials and marketing materials say. Latency is hardly ever mentioned.
      - jessriedel 8y ago
        Put the average consumer on a gigabit connection with 5 sec of latency and ask them how fast it is.
- JohnJamesRambo 8y ago
  Yes people have been burned by HughesNet and garbage like that. But it won’t take much to educate them, people can understand the difference. A simple graph showing the ping times and people will get it.
  - shaklee3 8y ago
    I suppose this argument works really well on HN. how many people do you think know or care about a ping time? if they did, don't you think we would see all of the commercials for broadband bragging about their latency instead of bandwidth? Streaming media dominates the internet today, and that's unaffected by high latency.
tomjakubowski 8y ago
How badly does "weather" affect TCP latency over an LEO satellite internet pipe?
- oh_sigh 8y ago
  Depends on the frequencies being used. Starlink is in the ku and ka band so it will be affected by weather, especially heavy rain or snow(called rain or snow fade in the field) Standard solution to rain fade is to make sure you have a power budget and can ramp power when heavy rain starts.
  - tomjakubowski 8y ago
    Thanks! Especially thanks for the terminology, that's very helpful to look up more about it.
shookness 8y ago
Here is a neat simulation of a proposed network: https://www.youtube.com/watch?v=QEIUdMiColU https://www.youtube.com/watch?v=QEIUdMiColU
- sprigyig 8y ago
  Admittedly I haven't researched it that well, but I'm curious how often they would have to aim their sensors at the sun to receive from a neighboring satellite. I'd have to assume those links would need to be subtracted from the system, which could slightly drive up latency around sun up and sun down for a part of the planet.
  - Veedrac 8y ago
    The sun is pretty small compared to space, something like .0005% of the full sky sphere, and almost half that time it's covered by Earth. Since there's no atmospheric glare in space, I suspect it's not a problem given decent engineering.
    - londons_explore 8y ago
      There are still internal reflections within the optical system - glare from that will likely be much larger than atmospheric glare
      - Veedrac 8y ago
        Given communication is point-to-point, and very coherent, I'd think this is extremely easy to solve if glare in the system was a real issue. Aim the receiver through a tube (or array of tubes) painted black, for instance. Certainly easier than building an equally precise telescope.
marcell 8y ago
Could you define the acronyms you use please? LEO, GEO, SLO
- FlyingAvatar 8y ago
  LEO - Low Earth Orbit GEO - Geosynchronous Earth Orbit SOL - Speed of Light
- deleted 8y ago
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- deleted 8y ago
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- munk-a 8y ago
  I believe: LEO - Low earth orbit (close to the earth) GEO - Geostationary equatorial orbit (further from the earth, more efficient in terms of energy required to maintain a fixed position[1]) SOL - Speed of Light (a limiting factor in fiber optic communications - and over the air communications as well) [1] From reading a bit, maintaining a fixed position relative to the ground at lower altitudes involves a constant velocity adjustment in the form of fuel expenditure - the equilibrium for each orbital period corresponds to a single altitude, so different orbital periods (when minimizing fuel usage) imply different distances.
  - TeMPOraL 8y ago
    Re [1], you generally can't do fixed positions anywhere else but GEO. Trying to stay stationary at a lower altitude would require using amounts of fuel that are way beyond what we can put in space. Note that GEO satellites do carry fuel with them for "stationkeeping" - between errors in navigation, variation of Earth's gravity (due to it's irregular shape and composition) and influence of solar radiation and other celestial bodies, those satellites do have to occasionally and very slightly adjust their orbit to stay stationary.
    - munk-a 8y ago
      Sorry yes, I was trying to express that but I think it came across unclearly - maintaining an unstable orbit requires a constant expenditure of fuel.
isignal 8y ago
The problem I have heard isn't so much latency but path to profitability. Unlike GEO satellites, LEO based internet is not going to be fully operational until a significant number of satellites are up there to provide continuous coverage at a single point on earth. Financially, this makes for a very front-loaded-capital / debt-intensive business which will falter unless subscriber numbers and technology all pan out exactly as estimated.
- munk-a 8y ago
  If you could actually compete against fiber I feel like the funding would be very easy to acquire if your first step was linking up the various stock exchanges - those guys pay up the nose for even slight latency decreases.
  - oarsinsync 8y ago
    This isn't going to be lower latency than existing low latency solutions. EDIT: For more context, the old low latency fiber path between Chicago and New York was under 7ms, and current low latency radio solutions are under 4ms. SpaceX's solution is marketed as being "as low as 25ms".
    - maccam94 8y ago
      It will matter for international trading, however.
ethagknight 8y ago
No consumer will worry about latency or any other component of the physical feat of delivering internet via Starlink. Consumers are currently buying downstream bandwidth by the mbps from one or maybe two providers with no other options. Only technology oldheads who remember satphones and Hughesnet will worry, then research, then try it out for themselves. Starlink has the added benefit of being very easy to give a “consumer trial period.” It will sell itself, in the USA at least.
- peteretep 8y ago
  > No consumer will worry about latency I think this would only be true if internet gamers weren't a thing, but they are, and they'll care.
  - chii 8y ago
    competitive gamers make up a very small percentage of all internet users (or even gamers!). Like professional athletes, they will move or go to a special facility for this sort of latency requirement. Many games are not as latency sensitive as you think - people used to play over modems!
    - cjarrett 8y ago
      Starcraft on my dial-up!
      - Joakal 8y ago
        The latency is copper to your home. Dial ups are as fast as broandband but throughput low.
        JauntyHatAngle 8y ago
        You might want to do some googling, that is absolutely not true for a few reasons that are not about throughput.
        8y ago
munk-a 8y ago
Elon should really do a John Henry if he can afford to set it up. Run a head-to-head data-transmission with checksum validation in some theatrical setting. For bonus points he could (if it's possible) run a self-driving car demo where the computation is being done and relaid by a LEO uplink. Also, I hear what you're saying but... Right now the Algorithmic traders all use fiber and new fiber is constantly being rolled out to support even lower latency connections so I'm skeptical - if it was competitive wouldn't G&S be using it to contact the London stock exchange? Or, is it that fiber can produce lower latency in idyllic scenarios but that congestion pushes the latency beyond that accomplishable by an LEO setup for us plebs?
- nitrogen 8y ago
  I remember reading about line-of-sight microwave links being used for trading here on HN. I think line of sight is the key difference between fiber and radio.
  - 01100011 8y ago
    Microwave, or even HF. Definitely using direct RF links though.
  - hermitdev 8y ago
    I dont know if I'd call it direct line of site, but low bandwidth directional microwave communication is definitely used over-the-horizon from say Chicago to London. This [1] Bloomberg article has a great rundown on microwave in finance. Bandwidth is low, but latency beats fibre, and you can bounce microwave off the ionosphere between London and Chicago (and various other routes). This article doesn't mention the cross Atlantic transmissions, but it is possible, and does happen. Disclosure: I have worked at several of the Chicago based firms mentioned in the linked Bloomberg article. Edit: grammar, formatting. I wasnt directly involved in any of the microwave networking, but ask me what you want and I'll answer to the best of my ability. [1] https://www.bloomberg.com/news/features/2019-03-08/the-gazillion-dollar-standoff-over-two-high-frequency-trading-towers https://www.bloomberg.com/news/features/2019-03-08/the-gazil...
  - 8y ago
drb91 8y ago
Not everyone has realtime needs. If you're not voice chatting or playing realtime games it's not that bad.
- BinaryIdiot 8y ago
  Even in voice chat's case latency isn't a huge issue until you get really high numbers. But you're right, even higher latencies can fit the 80% or even the 90% use case.
nsilvestri 8y ago
A misconception probably due to an overestimation of how far away space really is; the ISS only orbits at roughly 240 +/- 30 miles, and the (admittedly arbitrary) boundary of space is at 60 mi (100 km).
- KeenFox 8y ago
  The boundary of space varies depending on who you ask. https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line
  - wongarsu 8y ago
    The article implies more uncertainty than there is. To my knowledge everyone agrees to define the edge of space at 100km (about 62 miles), with the exception of the US where for historical reasons the edge of space is seen as 50 miles above sea level. There is no international agreement, but even though the line is arbitrary there is no huge variety of widely held opinions.
dragonwriter 8y ago
> So there is a cross over point where the latency of a LEO satellite system is actually superior despite the uplink/downlink path. There is, but given the rise of the use of edge caching and edge compute for latency-sensitive applications, with edge locations located to optimize access to masses of users, that crossover is unlikely to be actually reached in many of the cases where latency is actually a concern, and Starlink is going to be stuck behind unless it is able to both get edge caching and edge compute on its satellites and get content/service providers to use it, and comsats aren't exactly optimal locations for that.
- drb91 8y ago
  Latency is also much less important with highly cacheable content. At least, I can’t really think of examples to the contrary. My patience for loading pages browsing is many orders of magnitude higher than realtime uses. Bandwidth seems to dominate in this context. Latency of multiple seconds, like you can see in some places around the world, is much more frustrating than the kind of latency discussed wrt Starlink. The lack of a close edge node is kind of interesting, though, so i’m not trying to dismiss your comment in the least. Edit: wording
inflatableDodo 8y ago
>many important routes will have significantly lower latency than any feasible terrestrial system Is that accounting for recent developments in hollow core fibers? >"The researchers successfully demonstrated the first high-capacity, low-latency data transmission experiment performed using a hollow-core fibre. In this, they found that light propagated 31 per cent quicker than in a solid core fibre, increasing from 70 per cent of its full speed in a vacuum to 99.7 per cent. To put this in context, this means that data propagating in this fibre would arrived 1.54 microseconds/per km earlier that it would in an equivalent length of conventional solid fibre. Not only did the light almost travel at its fastest possible speed, but it did so with a very low loss of 3.5 dB per kilometre." https://www.southampton.ac.uk/news/2013/04/speed-of-light-fibre-optic.page https://www.southampton.ac.uk/news/2013/04/speed-of-light-fi...
- topspin 8y ago
  > Is that accounting for recent developments in hollow core fibers? No, it doesn't. You're citing a story from 2013. Has this seen deployment in the field? I haven't found any evidence of this. That makes me wonder what is missing in this story.
  - inflatableDodo 8y ago
    That story was the first ever measurement of light speed in a new fiber technology, so it was obviously still in the lab at that stage. It is still really an emerging research field, here's something more up to date - https://www.laserfocusworld.com/articles/print/volume-54/issue-05/newsbreaks/hollow-core-fibers-deliver-ultraviolet-light-without-solar-degradation.html https://www.laserfocusworld.com/articles/print/volume-54/iss... But you can purchase it these days - https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=912 https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=91... Also, I would think that the first transatlantic cable of this stuff might be kept pretty exclusive, given the economic opportunity presented by pissing around on the stock exchange. edit - here's some more recent press from the Southampton lot - https://www.ses.ac.uk/2019/04/03/fibre-optics/ https://www.ses.ac.uk/2019/04/03/fibre-optics/
dreamcompiler 8y ago
Latency's not going to be a problem. What is going to be a problem is what nobody is talking about: LEO satellites move. This means the downlink antenna has to have motors and move too, or it has to be a phased array and be expensive.
- diminoten 8y ago
  That's the innovation this is taking advantage of -- the downlink antenna will be tiny and can be embedded. This is a new market, not entering into an existing market.
  - dreamcompiler 8y ago
    I'm sorry but you are incorrect. You cannot innovate your way around the laws of physics. Do you want 5 Mbps from a LEOSAT? Fine, you need a pointable antenna. An Iridium-style omni antenna cannot accomplish this. The S/N ratio is simply too low.
    - diminoten 8y ago
      Sorry, but there are no laws of physics preventing innovation in the antenna space.
      - dreamcompiler 8y ago
        I suggest you study information theory and antenna theory. What you are suggesting is theoretically impossible. If a satellite could paint the continent with a megawatt, it might work. But satellites transmit with tens of watts, which gets spread over a large geographic area. The ground antenna must be pointed for decent bandwidth, either physically (with motors) or virtually (phased array) to achieve the requisite S/N ratio.
        shaklee3 8y ago
        This is correct. Basic antenna theory covers C/N and how it relates to antenna size. There's no magic allowed.
PaulHoule 8y ago
Latency does not worry me, but the economics do. An LEO satellite constellation has a bad urban/rural problem because most of the Earth's surface is ocean, uninhabited or uninhabitable. In the meantime, people from New York City and Detroit who hate their cable company will compete for network resources for people in the middle. To take advantage of those thousands of satellites, subscribers will need to install high-performance phased array antennas that will probably cost at least $6000. There will be the capital costs for the space segment, also since the system is just a bent pipe to Verizon, AT&T or whoever your local rent-seeker is, they will take a cut. Thus it is likely to be a very expensive service.
- brianwawok 8y ago
  Any source on needing a $6,000 antenna to get spaceX internet? That would be a deal killer but haven't heard that.
- coralreef 8y ago
  Why do you think people who live in cities will want satellite internet?
  - PaulHoule 8y ago
    Because they hate the cable company, because some of them have outrageous amounts of money, because some of them would like to have a backup connection, and because they are crammed in tight so even if the takeup is only 1% they still will consume a lot.
    - jeffdavis 8y ago
      Isn't a lot of demand good for the economincs of this service?
- topspin 8y ago
  > will probably cost at least $6000 What is your source for that figure? If it's military/aviation/naval phased array radar this is a very different use case. The targets are transceiving from well known locations, not maneuvering to reduce signature. The orbiting target is well above the horizon, not hidden in clutter. There are well defined frequency bands so high frequency agility is not necessary. There are no purpose built enemy jammers to overcome so extraordinary power levels or heroic filters aren't necessary. There are no afterburners or naval catapults to withstand. About the worse case I know of with the bands involved in this system is rain fade or snow cover. We already have MIMO beamforming transceivers at nearly disposable prices in the form of wifi routers. I think it's entirely feasible to develop a fixed function civilian phased array at a reasonable cost. Anyhow, with any luck we'll know soon.
broabprobe 8y ago
I feel like a majority of people falsely think the cell phone in their pocket talks to satellites anyway. So a space delivered ISP might not be a big shock for people.
sbr464 8y ago
As someone who has run a tiny ISP in a tiny town, I assure you “people” are much more knowledgeable than you assume. I was actually able to disable all monitoring systems, since I would get a phone call, immediately following any event that caused high latency, or any kind of internet disturbance. I learned that people who live in smaller rural towns are in some way much more dependent on the internet to provide things like entertainment, news, info, media, since there are fewer social events, theaters (etc, etc).
- KajMagnus 8y ago
  > "I would get a phone call, immediately following any event that caused high latency" Also at like 04:00 in the morning? :- )
  - londons_explore 8y ago
    Probably means someone thinks your service is shoddy and they set up their own monitoring.
dehrmann 8y ago
> fiber isn't latency free. It isn't even speed of light. It's about 70% SOL. There's use cases (high-frequency trading) where maintaining faster-than-fiver microwave links makes a lot of sense. https://arstechnica.com/information-technology/2016/11/private-microwave-networks-financial-hft/ https://arstechnica.com/information-technology/2016/11/priva...
analog31 8y ago
I wonder if this is a temporary software design problem. I mean, we have response time to burn these days, so we design with that in mind. If latency became a fact of life due to demand for a better deal on Internet access, maybe people will figure out how to make software that doesn't depend so much on a tight server loop.
divbzero 8y ago
Given that speed of light is ~3×10⁸ m/s an additional ~1,000 km (10⁶ m) up and down and back again would increase latency on the order of ~10 ms (10⁻² s). ~10 ms of additional latency isn’t wildly out-of-sync with real world latencies of ~40 ms within North America and ~70 ms across the Atlantic. [1] And if we factor in the ~30% reduction of speed of light in fiber, the delta might actually be less than ~10 ms. [1]: https://enterprise.verizon.com/terms/latency/ https://enterprise.verizon.com/terms/latency/
acchow 8y ago
Most people think their cell phone signals go to space.
blotter_paper 8y ago
>many important routes will have significantly lower latency than any feasible terrestrial system. Neutrinos brah.
mmaunder 8y ago
Sorry no offence but why is this even a conversation? I use Hughes which is geostationary. 600 to 900ms latency. That is around 35000 km altitude. These will be hundreds of km altitude. Kinda basic math to get the answer here.
grahamburger 8y ago
It will only take a few real customers talking about the latency being fine to make this a non-issue. It's very easy for people to test on their own. I doubt they'll have to do much specific marketing about this issue.
7e 8y ago
Why do you think that satellite to satellite routing will be particularly fast? There are a lot of hops, some satellites are moving relative to one another, and the satellites are power and bandwidth constrained. It sounds like a latency nightmare.
- greglindahl 8y ago
  Consumer connections will use bent pipes. Satellite to satellite links are limited and will be mostly used by high paying customers like high frequency traders.
deleted 8y ago
[deleted]
Scoundreller 8y ago
And Ground infrastructure doesn’t exactly take a straight path either. Add 5-10% slack in the line for loops/splice trays/pole movement, and then going around artificial and natural barriers...
- Corrado 8y ago
  When AWS introduced Ground Station [0] I was unsure as to their motivation. Looking back on it, this kind of endeavour might have been the impetus for the service. In fact, given how much of the "Internet" depends on AWS, SpaceX using Ground Station might actually lower latency to your favorite website. [0] https://aws.amazon.com/ground-station/ https://aws.amazon.com/ground-station/
fxfan 8y ago
I don't know about the LEO numbers but quick back of the envelop calculation assuming 1000 km means this latency would be nearly 3 ms.
sametmax 8y ago
Honestly I will be fine with bad latency if I can get reliable wireless internet anywhere on earth. If I need good latency, like for playing games, I will go to a location with fiber. I really, really think SpaceX Internet can do a lot of good. It may force competition. It may give internet access to many countries where it's not an option. It may even help fight censorship, or open the door to an alternative to the current internet network. Lots of potential.
Shivetya 8y ago
Reminds me of the story recently which mentioned Grace Hopper and her famous visual representation of how far information could travel in a nanosecond when answering a question about why satellite communications takes so long.
new_realist 8y ago
Local latency might be okay (worse then fiber, slightly worse than cable) but using space based routing is going to be a poor experience. There are a lot of latency-adding hops in space, and the terrestrial link bandwidth is so poor that popular destinations (LA or NYC) are going to be congested at their terminal endpoints, meaning you'll go the long way around and exit the satellites at a farther, more rural base station than is ideal, and use fiber for the final hops.

stcredzero 8y ago

SpaceX actually intends to compete with terrestrial systems on latency; many routes will have significantly lower latency than any feasible terrestrial system. I would like to see a framework, where the backend of a cloud system can migrate opposite to the direction of orbit, so the same virtual cloud server could remain (by 'hops' where it serializes a copy of itself, then fails over to the copy) more or less geostationary. Such migrations would happen as seldom as once per 10 minutes. My game server cluster isn't too far away from having such a capability. (I was planning a variety of capabilities, such as using cheap GCP "ephemeral" instances by quickly failing over to such copies.)

jtchang 8y ago
This is basically vmware's vmotion feature.
- stcredzero 8y ago
  That's quite cool. I'm doing my feature at more of an API level. That said, many applications still need to be architected to do this sort of migration well. The turnkey version just guarantees a demo version. (As technology develops, the turnkey capability will increase, but people's demands on the technology will also increase.)
smachiz 8y ago
Why would you need to do this? The constellation still needs downlinks - and the downlink nearest the physical location of the user should always be where that traffic pops back onto the Internet.
- stcredzero 8y ago
  For a game server cluster, I would be running a game loop implemented as a series of pure function functor-like objects, located "very near" a spatial database. In that case, I would be migrating to provide the very lowest latency, as if the system were running on a "geostationary" server just a few hundred miles overhead. (Which has to pause for a quarter second, once every several minutes.)
  - imtringued 8y ago
    That sounds like a terrible experience. You want to avoid latency spikes at all costs. People might not like latencies as high as 100ms to 200ms but it definitively is possible to enjoy a laggy game like that. Suddenly getting a 500ms latency every minute will cause a lot of weird and unfair situations that can basically ruin the entire game.
    - chupasaurus 8y ago
      I agree, jitter bigger than a synchronization time is worse than high latency. When player have high latency (and I was in top3 on NA Solo ladder in League of Legends while playing from Urals with 220ms), he could only predict the moves of the opponent because what you see is far behind the server state, but with stable latency he knows the exact delay between an input and registering it on the server which puts less pressure to mind to deal with desynchronization between the picture on a display and the actual state.
      - stcredzero 8y ago
        I agree, jitter bigger than a synchronization time is worse than high latency. I'll always grant that fast twitch FPS will always have a problem with this. That's not the genre I'm interested in creating games for, and it's not what my server framework is designed to support. (It is real-time action, but the pacing is more akin to RTS than FPS.)
wbl 8y ago
If only there was a large mass of rock and mud that was geostationary.
TeMPOraL 8y ago
Wait, what? Are you planning to put your game server in orbit? Because otherwise I don't understand what you're asking - a server on the ground will always be "geostationary" - it's the satellites it talks to that will change.

starpilot 8y ago

He's halving altitude to 550 km, in ideal cases bringing latency to 15 ms. Some satellites will be even lower, 350 km, for populated areas. https://arstechnica.com/tech-policy/2019/04/spacex-changes-broadband-satellite-plan-to-limit-debris-and-lower-latency/ https://arstechnica.com/tech-policy/2019/04/spacex-changes-b...

jayess 8y ago
I presume that's just one direction?
RHSeeger 8y ago
Is it 15ms to the satellite? If so, that's like 30ms to land, which would negatively impact gaming if it still needs to travel from where it lands to the end goal (via normal pathing?)
- slenk 8y ago
  30ms is a good ping for games... edit - yeah I forgot about the endpoint then to the game servers data center
  - jalgos_eminator 8y ago
    The 30ms figure is just the earth->satellite->earth part though. It still has to go through terrestrial wires to the server, and then be processed, and back through wires to the transmitter.
    - imtringued 8y ago
      Datacenters make deals with network providers. Why should it be any different with Starlink?
  - earenndil 8y ago
    That's not 30ms ping, that's add 30ms ping.

shaklee3 8y ago

The high latency questions are only from people who really don't understand the industry. The question most analysts in the industry ask are about how they plan to be profitable.

rurp 8y ago
"People who don't understand the industry" describes nearly all potential customers. I don't think this refutes the GPs point.
- jessriedel 8y ago
  Most potential customers don't know the difference between bandwidth and latency, they just think of it as speed.
  - shaklee3 8y ago
    I disagree. I think people equate bandwidth with speed, because that's what all of the commercials and marketing materials say. Latency is hardly ever mentioned.
    - jessriedel 8y ago
      Put the average consumer on a gigabit connection with 5 sec of latency and ask them how fast it is.
JohnJamesRambo 8y ago
Yes people have been burned by HughesNet and garbage like that. But it won’t take much to educate them, people can understand the difference. A simple graph showing the ping times and people will get it.
- shaklee3 8y ago
  I suppose this argument works really well on HN. how many people do you think know or care about a ping time? if they did, don't you think we would see all of the commercials for broadband bragging about their latency instead of bandwidth? Streaming media dominates the internet today, and that's unaffected by high latency.

tomjakubowski 8y ago

How badly does "weather" affect TCP latency over an LEO satellite internet pipe?

oh_sigh 8y ago
Depends on the frequencies being used. Starlink is in the ku and ka band so it will be affected by weather, especially heavy rain or snow(called rain or snow fade in the field) Standard solution to rain fade is to make sure you have a power budget and can ramp power when heavy rain starts.
- tomjakubowski 8y ago
  Thanks! Especially thanks for the terminology, that's very helpful to look up more about it.

shookness 8y ago

Here is a neat simulation of a proposed network: https://www.youtube.com/watch?v=QEIUdMiColU https://www.youtube.com/watch?v=QEIUdMiColU

sprigyig 8y ago
Admittedly I haven't researched it that well, but I'm curious how often they would have to aim their sensors at the sun to receive from a neighboring satellite. I'd have to assume those links would need to be subtracted from the system, which could slightly drive up latency around sun up and sun down for a part of the planet.
- Veedrac 8y ago
  The sun is pretty small compared to space, something like .0005% of the full sky sphere, and almost half that time it's covered by Earth. Since there's no atmospheric glare in space, I suspect it's not a problem given decent engineering.
  - londons_explore 8y ago
    There are still internal reflections within the optical system - glare from that will likely be much larger than atmospheric glare
    - Veedrac 8y ago
      Given communication is point-to-point, and very coherent, I'd think this is extremely easy to solve if glare in the system was a real issue. Aim the receiver through a tube (or array of tubes) painted black, for instance. Certainly easier than building an equally precise telescope.

marcell 8y ago

Could you define the acronyms you use please? LEO, GEO, SLO

FlyingAvatar 8y ago
LEO - Low Earth Orbit GEO - Geosynchronous Earth Orbit SOL - Speed of Light
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munk-a 8y ago
I believe: LEO - Low earth orbit (close to the earth) GEO - Geostationary equatorial orbit (further from the earth, more efficient in terms of energy required to maintain a fixed position[1]) SOL - Speed of Light (a limiting factor in fiber optic communications - and over the air communications as well) [1] From reading a bit, maintaining a fixed position relative to the ground at lower altitudes involves a constant velocity adjustment in the form of fuel expenditure - the equilibrium for each orbital period corresponds to a single altitude, so different orbital periods (when minimizing fuel usage) imply different distances.
- TeMPOraL 8y ago
  Re [1], you generally can't do fixed positions anywhere else but GEO. Trying to stay stationary at a lower altitude would require using amounts of fuel that are way beyond what we can put in space. Note that GEO satellites do carry fuel with them for "stationkeeping" - between errors in navigation, variation of Earth's gravity (due to it's irregular shape and composition) and influence of solar radiation and other celestial bodies, those satellites do have to occasionally and very slightly adjust their orbit to stay stationary.
  - munk-a 8y ago
    Sorry yes, I was trying to express that but I think it came across unclearly - maintaining an unstable orbit requires a constant expenditure of fuel.

isignal 8y ago

The problem I have heard isn't so much latency but path to profitability. Unlike GEO satellites, LEO based internet is not going to be fully operational until a significant number of satellites are up there to provide continuous coverage at a single point on earth. Financially, this makes for a very front-loaded-capital / debt-intensive business which will falter unless subscriber numbers and technology all pan out exactly as estimated.

munk-a 8y ago
If you could actually compete against fiber I feel like the funding would be very easy to acquire if your first step was linking up the various stock exchanges - those guys pay up the nose for even slight latency decreases.
- oarsinsync 8y ago
  This isn't going to be lower latency than existing low latency solutions. EDIT: For more context, the old low latency fiber path between Chicago and New York was under 7ms, and current low latency radio solutions are under 4ms. SpaceX's solution is marketed as being "as low as 25ms".
  - maccam94 8y ago
    It will matter for international trading, however.

ethagknight 8y ago

No consumer will worry about latency or any other component of the physical feat of delivering internet via Starlink. Consumers are currently buying downstream bandwidth by the mbps from one or maybe two providers with no other options. Only technology oldheads who remember satphones and Hughesnet will worry, then research, then try it out for themselves. Starlink has the added benefit of being very easy to give a “consumer trial period.” It will sell itself, in the USA at least.

peteretep 8y ago
> No consumer will worry about latency I think this would only be true if internet gamers weren't a thing, but they are, and they'll care.
- chii 8y ago
  competitive gamers make up a very small percentage of all internet users (or even gamers!). Like professional athletes, they will move or go to a special facility for this sort of latency requirement. Many games are not as latency sensitive as you think - people used to play over modems!
  - cjarrett 8y ago
    Starcraft on my dial-up!
    - Joakal 8y ago
      The latency is copper to your home. Dial ups are as fast as broandband but throughput low.
      - JauntyHatAngle 8y ago
        You might want to do some googling, that is absolutely not true for a few reasons that are not about throughput.
      - 8y ago

munk-a 8y ago

Elon should really do a John Henry if he can afford to set it up. Run a head-to-head data-transmission with checksum validation in some theatrical setting. For bonus points he could (if it's possible) run a self-driving car demo where the computation is being done and relaid by a LEO uplink. Also, I hear what you're saying but... Right now the Algorithmic traders all use fiber and new fiber is constantly being rolled out to support even lower latency connections so I'm skeptical - if it was competitive wouldn't G&S be using it to contact the London stock exchange? Or, is it that fiber can produce lower latency in idyllic scenarios but that congestion pushes the latency beyond that accomplishable by an LEO setup for us plebs?

nitrogen 8y ago
I remember reading about line-of-sight microwave links being used for trading here on HN. I think line of sight is the key difference between fiber and radio.
- 01100011 8y ago
  Microwave, or even HF. Definitely using direct RF links though.
- hermitdev 8y ago
  I dont know if I'd call it direct line of site, but low bandwidth directional microwave communication is definitely used over-the-horizon from say Chicago to London. This [1] Bloomberg article has a great rundown on microwave in finance. Bandwidth is low, but latency beats fibre, and you can bounce microwave off the ionosphere between London and Chicago (and various other routes). This article doesn't mention the cross Atlantic transmissions, but it is possible, and does happen. Disclosure: I have worked at several of the Chicago based firms mentioned in the linked Bloomberg article. Edit: grammar, formatting. I wasnt directly involved in any of the microwave networking, but ask me what you want and I'll answer to the best of my ability. [1] https://www.bloomberg.com/news/features/2019-03-08/the-gazillion-dollar-standoff-over-two-high-frequency-trading-towers https://www.bloomberg.com/news/features/2019-03-08/the-gazil...
- 8y ago

drb91 8y ago

Not everyone has realtime needs. If you're not voice chatting or playing realtime games it's not that bad.

BinaryIdiot 8y ago
Even in voice chat's case latency isn't a huge issue until you get really high numbers. But you're right, even higher latencies can fit the 80% or even the 90% use case.

nsilvestri 8y ago

A misconception probably due to an overestimation of how far away space really is; the ISS only orbits at roughly 240 +/- 30 miles, and the (admittedly arbitrary) boundary of space is at 60 mi (100 km).

KeenFox 8y ago
The boundary of space varies depending on who you ask. https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line
- wongarsu 8y ago
  The article implies more uncertainty than there is. To my knowledge everyone agrees to define the edge of space at 100km (about 62 miles), with the exception of the US where for historical reasons the edge of space is seen as 50 miles above sea level. There is no international agreement, but even though the line is arbitrary there is no huge variety of widely held opinions.

dragonwriter 8y ago

> So there is a cross over point where the latency of a LEO satellite system is actually superior despite the uplink/downlink path. There is, but given the rise of the use of edge caching and edge compute for latency-sensitive applications, with edge locations located to optimize access to masses of users, that crossover is unlikely to be actually reached in many of the cases where latency is actually a concern, and Starlink is going to be stuck behind unless it is able to both get edge caching and edge compute on its satellites and get content/service providers to use it, and comsats aren't exactly optimal locations for that.

drb91 8y ago
Latency is also much less important with highly cacheable content. At least, I can’t really think of examples to the contrary. My patience for loading pages browsing is many orders of magnitude higher than realtime uses. Bandwidth seems to dominate in this context. Latency of multiple seconds, like you can see in some places around the world, is much more frustrating than the kind of latency discussed wrt Starlink. The lack of a close edge node is kind of interesting, though, so i’m not trying to dismiss your comment in the least. Edit: wording

inflatableDodo 8y ago

>many important routes will have significantly lower latency than any feasible terrestrial system Is that accounting for recent developments in hollow core fibers? >"The researchers successfully demonstrated the first high-capacity, low-latency data transmission experiment performed using a hollow-core fibre. In this, they found that light propagated 31 per cent quicker than in a solid core fibre, increasing from 70 per cent of its full speed in a vacuum to 99.7 per cent. To put this in context, this means that data propagating in this fibre would arrived 1.54 microseconds/per km earlier that it would in an equivalent length of conventional solid fibre. Not only did the light almost travel at its fastest possible speed, but it did so with a very low loss of 3.5 dB per kilometre." https://www.southampton.ac.uk/news/2013/04/speed-of-light-fibre-optic.page https://www.southampton.ac.uk/news/2013/04/speed-of-light-fi...

topspin 8y ago
> Is that accounting for recent developments in hollow core fibers? No, it doesn't. You're citing a story from 2013. Has this seen deployment in the field? I haven't found any evidence of this. That makes me wonder what is missing in this story.
- inflatableDodo 8y ago
  That story was the first ever measurement of light speed in a new fiber technology, so it was obviously still in the lab at that stage. It is still really an emerging research field, here's something more up to date - https://www.laserfocusworld.com/articles/print/volume-54/issue-05/newsbreaks/hollow-core-fibers-deliver-ultraviolet-light-without-solar-degradation.html https://www.laserfocusworld.com/articles/print/volume-54/iss... But you can purchase it these days - https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=912 https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=91... Also, I would think that the first transatlantic cable of this stuff might be kept pretty exclusive, given the economic opportunity presented by pissing around on the stock exchange. edit - here's some more recent press from the Southampton lot - https://www.ses.ac.uk/2019/04/03/fibre-optics/ https://www.ses.ac.uk/2019/04/03/fibre-optics/

dreamcompiler 8y ago

Latency's not going to be a problem. What is going to be a problem is what nobody is talking about: LEO satellites move. This means the downlink antenna has to have motors and move too, or it has to be a phased array and be expensive.

diminoten 8y ago
That's the innovation this is taking advantage of -- the downlink antenna will be tiny and can be embedded. This is a new market, not entering into an existing market.
- dreamcompiler 8y ago
  I'm sorry but you are incorrect. You cannot innovate your way around the laws of physics. Do you want 5 Mbps from a LEOSAT? Fine, you need a pointable antenna. An Iridium-style omni antenna cannot accomplish this. The S/N ratio is simply too low.
  - diminoten 8y ago
    Sorry, but there are no laws of physics preventing innovation in the antenna space.
    - dreamcompiler 8y ago
      I suggest you study information theory and antenna theory. What you are suggesting is theoretically impossible. If a satellite could paint the continent with a megawatt, it might work. But satellites transmit with tens of watts, which gets spread over a large geographic area. The ground antenna must be pointed for decent bandwidth, either physically (with motors) or virtually (phased array) to achieve the requisite S/N ratio.
      - shaklee3 8y ago
        This is correct. Basic antenna theory covers C/N and how it relates to antenna size. There's no magic allowed.

PaulHoule 8y ago

Latency does not worry me, but the economics do. An LEO satellite constellation has a bad urban/rural problem because most of the Earth's surface is ocean, uninhabited or uninhabitable. In the meantime, people from New York City and Detroit who hate their cable company will compete for network resources for people in the middle. To take advantage of those thousands of satellites, subscribers will need to install high-performance phased array antennas that will probably cost at least $6000. There will be the capital costs for the space segment, also since the system is just a bent pipe to Verizon, AT&T or whoever your local rent-seeker is, they will take a cut. Thus it is likely to be a very expensive service.

brianwawok 8y ago
Any source on needing a $6,000 antenna to get spaceX internet? That would be a deal killer but haven't heard that.
coralreef 8y ago
Why do you think people who live in cities will want satellite internet?
- PaulHoule 8y ago
  Because they hate the cable company, because some of them have outrageous amounts of money, because some of them would like to have a backup connection, and because they are crammed in tight so even if the takeup is only 1% they still will consume a lot.
  - jeffdavis 8y ago
    Isn't a lot of demand good for the economincs of this service?
topspin 8y ago
> will probably cost at least $6000 What is your source for that figure? If it's military/aviation/naval phased array radar this is a very different use case. The targets are transceiving from well known locations, not maneuvering to reduce signature. The orbiting target is well above the horizon, not hidden in clutter. There are well defined frequency bands so high frequency agility is not necessary. There are no purpose built enemy jammers to overcome so extraordinary power levels or heroic filters aren't necessary. There are no afterburners or naval catapults to withstand. About the worse case I know of with the bands involved in this system is rain fade or snow cover. We already have MIMO beamforming transceivers at nearly disposable prices in the form of wifi routers. I think it's entirely feasible to develop a fixed function civilian phased array at a reasonable cost. Anyhow, with any luck we'll know soon.

broabprobe 8y ago

I feel like a majority of people falsely think the cell phone in their pocket talks to satellites anyway. So a space delivered ISP might not be a big shock for people.

sbr464 8y ago

As someone who has run a tiny ISP in a tiny town, I assure you “people” are much more knowledgeable than you assume. I was actually able to disable all monitoring systems, since I would get a phone call, immediately following any event that caused high latency, or any kind of internet disturbance. I learned that people who live in smaller rural towns are in some way much more dependent on the internet to provide things like entertainment, news, info, media, since there are fewer social events, theaters (etc, etc).

KajMagnus 8y ago
> "I would get a phone call, immediately following any event that caused high latency" Also at like 04:00 in the morning? :- )
- londons_explore 8y ago
  Probably means someone thinks your service is shoddy and they set up their own monitoring.

dehrmann 8y ago

> fiber isn't latency free. It isn't even speed of light. It's about 70% SOL. There's use cases (high-frequency trading) where maintaining faster-than-fiver microwave links makes a lot of sense. https://arstechnica.com/information-technology/2016/11/private-microwave-networks-financial-hft/ https://arstechnica.com/information-technology/2016/11/priva...

analog31 8y ago

I wonder if this is a temporary software design problem. I mean, we have response time to burn these days, so we design with that in mind. If latency became a fact of life due to demand for a better deal on Internet access, maybe people will figure out how to make software that doesn't depend so much on a tight server loop.

divbzero 8y ago

Given that speed of light is ~3×10⁸ m/s an additional ~1,000 km (10⁶ m) up and down and back again would increase latency on the order of ~10 ms (10⁻² s). ~10 ms of additional latency isn’t wildly out-of-sync with real world latencies of ~40 ms within North America and ~70 ms across the Atlantic. [1] And if we factor in the ~30% reduction of speed of light in fiber, the delta might actually be less than ~10 ms. [1]: https://enterprise.verizon.com/terms/latency/ https://enterprise.verizon.com/terms/latency/

acchow 8y ago

Most people think their cell phone signals go to space.

blotter_paper 8y ago

>many important routes will have significantly lower latency than any feasible terrestrial system. Neutrinos brah.

mmaunder 8y ago

Sorry no offence but why is this even a conversation? I use Hughes which is geostationary. 600 to 900ms latency. That is around 35000 km altitude. These will be hundreds of km altitude. Kinda basic math to get the answer here.

grahamburger 8y ago

It will only take a few real customers talking about the latency being fine to make this a non-issue. It's very easy for people to test on their own. I doubt they'll have to do much specific marketing about this issue.

7e 8y ago

Why do you think that satellite to satellite routing will be particularly fast? There are a lot of hops, some satellites are moving relative to one another, and the satellites are power and bandwidth constrained. It sounds like a latency nightmare.

greglindahl 8y ago
Consumer connections will use bent pipes. Satellite to satellite links are limited and will be mostly used by high paying customers like high frequency traders.

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Scoundreller 8y ago

And Ground infrastructure doesn’t exactly take a straight path either. Add 5-10% slack in the line for loops/splice trays/pole movement, and then going around artificial and natural barriers...

Corrado 8y ago
When AWS introduced Ground Station [0] I was unsure as to their motivation. Looking back on it, this kind of endeavour might have been the impetus for the service. In fact, given how much of the "Internet" depends on AWS, SpaceX using Ground Station might actually lower latency to your favorite website. [0] https://aws.amazon.com/ground-station/ https://aws.amazon.com/ground-station/

fxfan 8y ago

I don't know about the LEO numbers but quick back of the envelop calculation assuming 1000 km means this latency would be nearly 3 ms.

sametmax 8y ago

Honestly I will be fine with bad latency if I can get reliable wireless internet anywhere on earth. If I need good latency, like for playing games, I will go to a location with fiber. I really, really think SpaceX Internet can do a lot of good. It may force competition. It may give internet access to many countries where it's not an option. It may even help fight censorship, or open the door to an alternative to the current internet network. Lots of potential.

Shivetya 8y ago

Reminds me of the story recently which mentioned Grace Hopper and her famous visual representation of how far information could travel in a nanosecond when answering a question about why satellite communications takes so long.

new_realist 8y ago

Local latency might be okay (worse then fiber, slightly worse than cable) but using space based routing is going to be a poor experience. There are a lot of latency-adding hops in space, and the terrestrial link bandwidth is so poor that popular destinations (LA or NYC) are going to be congested at their terminal endpoints, meaning you'll go the long way around and exit the satellites at a farther, more rural base station than is ideal, and use fiber for the final hops.