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#starlink#satellitenetworking#latency

Using ground relays with Starlink

Mark Handley

7.5K subscribers • 2 videos on Hallway

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  • Recommended by 5 people: 5 on Hacker News.
  • Presented by Mark Handley, Professor at UCL

Intermediate. Assumes working knowledge.

506K views6 years ago5 recommendations

Distributed systemsSystems programmingNetworking and protocols

Mark Handley explains how early Starlink satellites can achieve low-latency wide-area communication by routing through ground relays.

The early SpaceX Starlink satellites lack inter-satellite links planned for later versions. Can they still provide low latency wide-area communications? In this video I look at what might be possible using ground relays to hop from satellite to satellite around the world. For more details: nrg.cs.ucl.ac.uk/mjh/starlink/

Why it's here

5 people recommend this

What people say. Recommended for its detailed simulation and analysis of Starlink network routing and latency.

sneakon Hacker News • Recommends

On “Realtime Starlink Satellite Map”

You don't need inter-satellite links for low latency, as Mark Handley has elegantly pointed out in his incredible video. I don't think internet access will amount to even 50% of the revenue of Starlink. link to this video
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thameron Hacker News • Recommends

On “Starlink Packet Routing”

I would highly recommend the video linked from this article: link to this video It's a simulation of the various ways in which the Starlink network could be arranged to route between satellites and ground stations; very detailed and super interesting.
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gadderson Hacker News • Recommends

On “SpaceX Starlink is now its own ASN and present at the Seattle Internet Exchange”

This 1 is a good youtube explanation of how a hybrid between Starlink and ground stations could still improve connectivity: 1 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 link to this video 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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sneakon Hacker News • Recommends

On “Realtime Starlink Satellite Map”

The orbital planes top parts are all up there at high latitudes. The circle you are seeing is actually made up of several different orbital planes that swoop down toward/past the equator and then up/down to 60 degrees N/S. Seeing them move will make it clearer. Here’s an awesome visual explanation with a ton of other cool info: link to this video
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sacred_numberson Hacker News • Recommends

On “Realtime Starlink Satellite Map”

A ground station doesn't have to actually be on the ground. They could park a boat in the ocean between London and NYC with equipment to act as a repeater. This YouTube video (along with others on this channel) does a good job of explaining how this could work. [video ]
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mhandleyon Hacker News • Mentions

On “Starlink Is a Big Deal”

These first satellites don't have the free-space lasers I modelled in that paper, but my simulations show they can still beat fibre on many paths without inter-satellite links, by relaying via groundstations: link to this video Later satellites will have inter-satellite links, but probably not till near the end of this year, and most of the first phase will already be deployed by then.
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mhandleyon Hacker News • Mentions

On “Network topology design at 27,000 km/hr”

Elon Musk has stated that until they have inter-satellite laser links deployed, they can get wide area low latency communications by relaying via ground stations at a high slant angle. I built a simulator and ran an analysis of this, and actually it works pretty well. My video analysing all this is here: link to this video
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mhandleyon Hacker News • Mentions

On “Does Tweeting Improve Citations? One-Year Results from a Randomized Trial”

The research community really should do a better job of engaging with the wider world, irrespective of whether it increases citations. For example, I had this paper in Hotnets 2019, and about 80 people saw my presentation. But I also spent some time, turned it into a little video and put it on YouTube. 360,000 people have seen it there. Now the subtleties were probably lost on many of those people, but if only a few of those people got something out of it, then it will likely have had more impact than the original paper. 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 And here without ISLs: link to this video 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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mhandleyon Hacker News • Mentions

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

Computationally, it's difficult, but I don't think it's intractable. Bear in mind this this is not an animation, but a real-time simulation: link to this video I'm running Dijkstra across this mesh at 30fps in real-time on my laptop while also doing the 3d animation. My laptop fan does spin a bit, but it's not crazily optimized code, and for the video I was also recording to H.264 simultaneously. Doing routing for all customers simultaneously is certainly feasible if their groundstations do the computation, based on routing state supplied in real-time by the constellation. Other solutions are probably possible too, but this seems simplest to me, and scales linearly with customers.
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shaklee3on Hacker News • Mentions

On “Realtime Starlink Satellite Map”

I didn't downvote you, but the size of the beam is heavily dictated by the elevation they're willing to work with, and the wider the elevation, the more expensive the antenna. So give that they need to decrease the size of the beam to keep antenna cost down, it's highly likely that the beam size is much, much smaller than what you cited there. Just take a look to see how many handoffs there are over CONUS alone: link to this video
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