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#starlink#satellitenetworking#latency

Starlink revisions, Nov 2018

Mark Handley

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  • Recommended by 4 people: 4 on Hacker News.
  • Presented by Mark Handley
  • May be out of date. The tools, versions or practices it shows have likely moved on.

Intermediate. Assumes working knowledge.

172K views7 years ago4 recommendations

Distributed systemsNetworking and protocolsScaling and large-scale architecture

Mark Handley analyzes and visualizes the routing paths, orbits, and network latency of SpaceX's revised 2018 Starlink constellation proposal.

This is a brief first look at what impact the changes to SpaceX's proposed starlink network from the new November 2018 filing might have on how the network functions. My original video, based on their original plans, that also shows phase 2 is here: youtube.com/watch?v=AdKNCBrkZQ4 The research paper discussing this in more details is here: nrg.cs.ucl.ac.uk/mjh/starlink-draft.pdf Additional information is here: nrg.cs.ucl.ac.uk/mjh/starlink/ Edit: Starlink RTTs in this video are all 8.7% higher than they should be due to an incorrect scaling factor being applied.

Why it's here

4 people recommend this

What people say. Recommended for its excellent visualizations and analysis of Starlink's satellite orbits, routing paths, and potential network latency.

cagenuton Hacker News • Recommends

On “First SpaceX Starlink satellites loaded into Falcon fairing”

this guy made an excellent youtube video modeling and visualizing the satellite orbits, the network routing paths across them, and the resulting latencies: link to this video NYC to London on the current internet is 76ms, he shows it across starlink's updated plans as working out to around 46ms. Later in the description he points out a mistake in his own math and says that starlink paths should be 8.7% faster than the video shows, so really jfk<->lhr ~ 42ms.
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rashomonon Hacker News • Recommends

On “First SpaceX Starlink satellites loaded into Falcon fairing”

The FCC filing has a lot of good technical details on the deployment and frequency usage. Additionally, Mark Handley has a good primer on it. It may kill actual east-west terrestrial traffic due to latency improvements: link to this video North-South will still be terrestrial.
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positr0non Hacker News • Recommends

On “Starlink – SpaceX’s broadband internet system”

Here's some great visualizations of the orbits and an explanation of what it means that the orbits are optimized for the northern hemisphere. (This confused me at first since obviously any orbit has to go just as far south as it does north of the equator.) link to this video
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cagenuton Hacker News • Recommends

On “FCC has “serious doubts” that SpaceX can deliver latencies under 100ms”

If you want a really great visualization and latency estimates for starlink check out the models and videos this guy came up with: link to this video link The comment from the FCC about it not accounting for "processing & routing" is kindof nonsense on its face, those are not novel problems they're already done by ever other router and switch, including several other satellite networks.
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paranoidroboton Hacker News • Recommends

On “SpaceX says Starlink now has over 10k users”

Mark Handley has done a bunch of videos analysing this on his channel0. The TLDR is that there is a lot of room for Starlink to beat existing terrestrial options IF they can get the laser links working on-orbit. This video1 shows estimates using what was known about proposed configurations in 2018 0 link 1 link to this video
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TrueDualityon Hacker News • Mentions

On “SpaceX just got FCC approval to launch 7,518 satellites”

There were recently two simulations done on possible latencies based on the FCC filings. You can find the video simulations in the links at the bottom of this post. You can see international links that have latencies lower than the existing internet by a significant margin. Unfortunately neither of those simulations take into account that the first iteration has been changed to only use radio and no laser links. 0: link 1: link to this video
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gvbon Hacker News • Mentions

On “Starlink – SpaceX’s broadband internet system”

At 5:03 1 he talks about how the laser links give good connectivity east-west but not as good north-south. 1 link to this video
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mhandleyon Hacker News • Mentions

On “FCC has “serious doubts” that SpaceX can deliver latencies under 100ms”

There's no doubt that this sort of technology can in principle deliver sub-100ms latencies. Take a look at my analysis here with inter-satellite links: link to this video And here without ISLs: link Now, these videos assume no queuing delay. It's really hard to guarantee low queuing delay in a traditional IP network, but there's been a lot of research over the years, and we have a range of ideas that can be used to deliver minimal queuing with reasonable utilization. In fact doing this for Starlink is something I'm actively researching at the moment. I'm convinced it can be done, but it won't look like a conventional IP network internally. I don't know what SpaceX will actually do, so if the FCC has…
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iso1210on Hacker News • Mentions

On “SpaceX Starlink average speedtest is 42.3Mbps down / 9.7 Mbps up”

link to this video is an animation of how it's supposed to work, including latencies There are enough satelites and low enough routing on the lasers to mean packets will arrive from London to NY faster than even a great-circle fibre. In reality how much bandwidth is available is a function of money, and HFTs tend to have a lot of money.
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lgatson Hacker News • Mentions

On “SpaceX sends laser-linked Starlinks to the polar orbit”

Forward and back looking lasers would have minimal speed difference, side laser links don't appear to be at extreme speed differences according to these hypothesized connections: link to this video
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kobalskyon Hacker News • Mentions

On “Ask HN: What lesser-known accessories do you use with your computer?”

> This might as be considered a law of physics - electromagnetic energy will always travel faster, more... through a conductive medium than through air. it actually travels faster through air (no vacuum necessary) than through fiber or copper as those transmit information at 2/3rd of the speed of light while air transmits it at 99% 1. which is why starlink could in theory achieve better latency than a straight run of fiber optic across the world 2. this of course doesn't mean that it's better in a mouse because of the overhead of processing such a short distance. 1 link 2 link to this video
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