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There is absolutely no way a satellite network can clear that kind of downlink bandwidth. Evergreen comment. Encoding and compression software and hardware con

by SEJeff 6y ago

There is absolutely no way a satellite network can clear that kind of downlink bandwidth. Evergreen comment. Encoding and compression software and hardware continue to improve. The only constant in technology is change. Will we be able to do this sort of bandwith to LEO eventually? Yes. Can we do it this very moment? No one has tried.

otterley 6y ago
Context is important, though. Network performance advances are always relative. If satellite fully-congested download speed improves 10x while hardwire link performance improves 10x, satellite will still be perceived as "too slow" by some segment. Our experience thus far has been that advances in applications tend to consume the bandwidth available. Whether that trend continues remains to be seen. (To be fair, I have never saturated my bidirectional 1GBps fiber link and I don't foresee ever doing so except for very brief periods of time.)
- DingoMeansDildo 6y ago
  Give this man a dildo, or a new beer, whatever he needs dudes. Bingo. Good answer.
rubber_duck 6y ago
> Encoding and compression software What does that have to do with bandwidth ?
- SEJeff 6y ago
  Sending less data over starlink (which is not tcp/ip btw). I’d you can make 10Mb suddenly only require 900k of actual raw bandwidth by say adding a fpga or something then you can increase throughout to the users.
  - bryanlarsen 6y ago
    Hopefully in 2020 most internet traffic is encrypted. If encrypted traffic is compressible you're doing it wrong.
    - BenjiWiebe 6y ago
      It would help if it was compressed pre-encryption, by the server.
  - Ekaros 6y ago
    If that big compression rates where achievable why wouldn't we be already using them? They would be standard in any network.
  - dreamcompiler 6y ago
    Technology only improves compression ratios to a certain point, and we passed that point with lossless compression decades ago. We're approaching that point with lossy compression now. Going beyond that point requires the laws of physics (more precisely, the laws of information theory) to change, and that's not going to happen.
jasonwatkinspdx 6y ago
There are underlying physical limitations to spectral efficiency. The best modulation schemes in use today can hit about 60 bits per second per hz of bandwidth. Meanwhile, single fibers top out above 40 terabit. To duplicate the bandwidth of just a single fiber link with a radio downlink, you'd need over 600 ghz of available spectrum. That'd require advances pushing deep into the thz gap, but beyond that, the physics of propagation are so different between 6 ghz, 60 ghz, and 600 ghz that it's hard to conceive of a single system covering so much spectrum. And that's not even getting into issues with geometric limitations of radio beam widths. While change is constant, this isn't an argument that any change you can imagine is physically realizable. Fiber is here to stay for a very long time precisely because it starts out with such massive fundamental physical advantages. It's also a mistake to assume innovation only benefits one alternative. We're still learning how to make and run fiber cheaper too.
- shaklee3 6y ago
  For what it's worth, satellite is typically around 1-4 bits per second per Hz.
- Tuna-Fish 6y ago
  > 60 bits per second per hz of bandwidth Between one transmitter and receiver. Starlink is designed to cheat Shannon by utilizing SDMA on a truly massive scale. Every antenna in the system, both on the satellites and on the ground stations, is a large phased-array antenna, capable of simultaneously emitting different signals on the same wavelength in different directions, and capable of discriminating between multiple different signals on the same wavelength that come from different directions. This is how Starlink intends to push so much throughput over just ~50 GHz of bandwidth. Not by pushing more bits per hz per link, but by filling the sky with hundreds of simultaneously visible satellites, and having each of them to all use all of the available spectrum at the same time on every link between any of them and any of the ground stations.
  - jasonwatkinspdx 6y ago
    Phased arrays aren't magic. The directivity of the beam scales logarithmically with array size / element count. The limitations are such that you should think of it as being able to send Nebraska one signal while you send Kansas a different one. You can't get much more specific than that. Elon has been very explicit about starlink never being competitive vs telcos in urban areas. And independent people have done the math too. The system geometry maxes out at less than a single fiber: http://www.mit.edu/~portillo/files/Comparison-LEO-IAC-2018-slides.pdf http://www.mit.edu/~portillo/files/Comparison-LEO-IAC-2018-s...
pier25 6y ago
> Encoding and compression software and hardware continue to improve. But these would apply to both wired and wireless, no?
- manquer 6y ago
  If encoding tech is specific to wireless then not really , just like improving cable medium , number of cable pairs etc will not improve wireless , better transmitter or receiver will not impact wired
  - shaklee3 6y ago
    What encoding technology is specific to wireless? (Hint: none)
    - manquer 6y ago
      You are thinking just software , Hardware tech is very different for wireless. The benefits from beam forming, MIMO or any of the advancements in 3G/4G/5G only benefit wireless. There has been similar technical improvements in wired which only benefit that medium, they keep cramming more signal on the same size cable every generation. Even in software at L3-7 the encoding tech is probably same of course, however protocols L0-2 is very medium dependent. The loss , noise, signal strength patterns all change depending on the medium so does Even at L4 and above UDP based stacks benefit in wireless compared TCP based transport, if your application can handle it of course. The next gen HTTP is getting designed around UDP in some part to reflect the changing way people access the internet , a lot more traffic is mobile and wireless today so designing around wireless makes sense. Personally even as app developer who works only with L7(HTTP) and L6 (SDP) I have specifically developed non trivial optimizations, workflows and APIs for mobile clients which were not needed or used by web clients due to different connection parameters of wired/ WiFi as opposed to wireless 2G/3G . So yes there is lot of difference and most people working at any layer cannot ignore the medium.
      - shaklee3 6y ago

by SEJeff 6y ago

otterley 6y ago

Context is important, though. Network performance advances are always relative. If satellite fully-congested download speed improves 10x while hardwire link performance improves 10x, satellite will still be perceived as "too slow" by some segment. Our experience thus far has been that advances in applications tend to consume the bandwidth available. Whether that trend continues remains to be seen. (To be fair, I have never saturated my bidirectional 1GBps fiber link and I don't foresee ever doing so except for very brief periods of time.)

DingoMeansDildo 6y ago
Give this man a dildo, or a new beer, whatever he needs dudes. Bingo. Good answer.

rubber_duck 6y ago

> Encoding and compression software What does that have to do with bandwidth ?

SEJeff 6y ago
Sending less data over starlink (which is not tcp/ip btw). I’d you can make 10Mb suddenly only require 900k of actual raw bandwidth by say adding a fpga or something then you can increase throughout to the users.
- bryanlarsen 6y ago
  Hopefully in 2020 most internet traffic is encrypted. If encrypted traffic is compressible you're doing it wrong.
  - BenjiWiebe 6y ago
    It would help if it was compressed pre-encryption, by the server.
- Ekaros 6y ago
  If that big compression rates where achievable why wouldn't we be already using them? They would be standard in any network.
- dreamcompiler 6y ago
  Technology only improves compression ratios to a certain point, and we passed that point with lossless compression decades ago. We're approaching that point with lossy compression now. Going beyond that point requires the laws of physics (more precisely, the laws of information theory) to change, and that's not going to happen.

jasonwatkinspdx 6y ago

There are underlying physical limitations to spectral efficiency. The best modulation schemes in use today can hit about 60 bits per second per hz of bandwidth. Meanwhile, single fibers top out above 40 terabit. To duplicate the bandwidth of just a single fiber link with a radio downlink, you'd need over 600 ghz of available spectrum. That'd require advances pushing deep into the thz gap, but beyond that, the physics of propagation are so different between 6 ghz, 60 ghz, and 600 ghz that it's hard to conceive of a single system covering so much spectrum. And that's not even getting into issues with geometric limitations of radio beam widths. While change is constant, this isn't an argument that any change you can imagine is physically realizable. Fiber is here to stay for a very long time precisely because it starts out with such massive fundamental physical advantages. It's also a mistake to assume innovation only benefits one alternative. We're still learning how to make and run fiber cheaper too.

shaklee3 6y ago
For what it's worth, satellite is typically around 1-4 bits per second per Hz.
Tuna-Fish 6y ago
> 60 bits per second per hz of bandwidth Between one transmitter and receiver. Starlink is designed to cheat Shannon by utilizing SDMA on a truly massive scale. Every antenna in the system, both on the satellites and on the ground stations, is a large phased-array antenna, capable of simultaneously emitting different signals on the same wavelength in different directions, and capable of discriminating between multiple different signals on the same wavelength that come from different directions. This is how Starlink intends to push so much throughput over just ~50 GHz of bandwidth. Not by pushing more bits per hz per link, but by filling the sky with hundreds of simultaneously visible satellites, and having each of them to all use all of the available spectrum at the same time on every link between any of them and any of the ground stations.
- jasonwatkinspdx 6y ago
  Phased arrays aren't magic. The directivity of the beam scales logarithmically with array size / element count. The limitations are such that you should think of it as being able to send Nebraska one signal while you send Kansas a different one. You can't get much more specific than that. Elon has been very explicit about starlink never being competitive vs telcos in urban areas. And independent people have done the math too. The system geometry maxes out at less than a single fiber: http://www.mit.edu/~portillo/files/Comparison-LEO-IAC-2018-slides.pdf http://www.mit.edu/~portillo/files/Comparison-LEO-IAC-2018-s...

pier25 6y ago

> Encoding and compression software and hardware continue to improve. But these would apply to both wired and wireless, no?

manquer 6y ago
If encoding tech is specific to wireless then not really , just like improving cable medium , number of cable pairs etc will not improve wireless , better transmitter or receiver will not impact wired
- shaklee3 6y ago
  What encoding technology is specific to wireless? (Hint: none)
  - manquer 6y ago
    You are thinking just software , Hardware tech is very different for wireless. The benefits from beam forming, MIMO or any of the advancements in 3G/4G/5G only benefit wireless. There has been similar technical improvements in wired which only benefit that medium, they keep cramming more signal on the same size cable every generation. Even in software at L3-7 the encoding tech is probably same of course, however protocols L0-2 is very medium dependent. The loss , noise, signal strength patterns all change depending on the medium so does Even at L4 and above UDP based stacks benefit in wireless compared TCP based transport, if your application can handle it of course. The next gen HTTP is getting designed around UDP in some part to reflect the changing way people access the internet , a lot more traffic is mobile and wireless today so designing around wireless makes sense. Personally even as app developer who works only with L7(HTTP) and L6 (SDP) I have specifically developed non trivial optimizations, workflows and APIs for mobile clients which were not needed or used by web clients due to different connection parameters of wired/ WiFi as opposed to wireless 2G/3G . So yes there is lot of difference and most people working at any layer cannot ignore the medium.
    - shaklee3 6y ago