TechCrunch story about this posted yesterday:
The Dunant subsea cable
161–170 of 262 posts
Re: The Dunant subsea cable
#162I know a lot is focusing on the Bandwidth. But are we making any progress on Long Distance Subsea Cable using Hollow Core Cable, achieving close to maximum speed of light for theoretical lowest latency possible? Imagine cutting latency from West Coast US to Hong Kong by 50ms! Light is only traveling at around 2/3 of speed within Fibre. The previous decades have been around Bandwidth. Is time we shift out focus to lat…
I agree, but we can start on our local machines first. Most of the latency of modern computers isn't related to the network.
Latency reduction like that would mostly be relevant for traders.
Re: The Dunant subsea cable
#163Earlier quoted context omitted.
Won't they be at low enough altitude that they'll need more hops than fiber to get around the globe, where each hop adds at least some delay?
Not sure what you mean by "hops" here? The current beta sats mostly act as "bent pipes", where they relay directly between user terminals and ground stations which then go to out to the regular net from there. But the final deployment sats are intended to have free space optical links between satellites (these are currently deployed and testing on the most recent polar orbit ones), so a connection can go entirely thr…
Also just to run the math on an example for "actually be much more direct for many people when crossing oceans": say someone is somewhere on the southern coast of Alaska, be it more towards King's Cove or back towards Newhalen, and want to talk to someone in Sapporo Japan. As the bird flies that's something like a 2500-3000 mile distance. But in practice there is no undersea cable direct linking Alaska and Asia (unless that's changed in the last year or two). Instead a connection probably has to go to Anchorage, then to Seattle, then probably to Tokyo, and then out to the rest of Japan from there. This could easily turn a 2500 mile path into a 7300 mile path. Starlink satellites in the current plan AFAIK are going to heavily be in shells 214 to 350 miles high (including Ku/Ka band current ones and future V-band ones). At 350 mi orbit, so maybe a 700-1000 mile up/down penalty, total distance could still be half the cable distance in this example, even before latency advantages.
Re: The Dunant subsea cable
#164I know a lot is focusing on the Bandwidth. But are we making any progress on Long Distance Subsea Cable using Hollow Core Cable, achieving close to maximum speed of light for theoretical lowest latency possible? Imagine cutting latency from West Coast US to Hong Kong by 50ms! Light is only traveling at around 2/3 of speed within Fibre. The previous decades have been around Bandwidth. Is time we shift out focus to lat…
My bet is on tech like Starlink with inter-satellite communication. Starlink should have lower latency with space lasers compared to fiber.
Starlink satellites are in orbit 550km high. So any journey would add at least 1100km. Moreover not sure that a single satellite would be able to hit another one across transpacific distances and may need to go through multiple hops to get there.
Each hop will add latency since signal needs regeneration. So it’s not clear to me a swarm of satellites is a real winner from a latency POV. Furthermore, given costs to put the constellation up there, it’s extremely expensive on a $/bit basis and not sure how it could compete against fiber.
The value of Starlink is providing service in areas lacking existing broadband infrastructure where the cost to provide service exceeds the cost of Starlink.
Re: The Dunant subsea cable
#165Earlier quoted context omitted.
That's interesting! But multimode fiber isn't feasible for thousands of kilometers? This is transatlantic. Wouldn't that have to be singlemode just for the distances involved?
Even single-mode needs repeaters along the length of the cable to get across an ocean. I guess you could use multimode and a lot more repeaters, but that seems more expensive and more failure-prone.
When I was first learning about fiber, graded-index multimode was the "hot new thing" with corning promising the modal-dispersion of single-mode fiber with the light-carrying capacity of multimode, which should reduce repeaters compared to either. Since these are single-mode fibers, I assume those promises were overstated?
Re: The Dunant subsea cable
#166Earlier quoted context omitted.
That is at least 1 order of magnitude cheaper than I would have guessed. Mind boggling that it's cheaper to do that then buy like the 4th best meal delivery app in Canada or whatever.
It's probably cheaper than people would expect because the long run across the deep ocean is a lot more straightforward than most people would expect. 1. For the deep ocean parts of the route, cables and associated equipment (such as repeaters) are simply spooled out from the back of the cable laying ship, to settle on the ocean floor. 2. For shallow waters, the cable is buried. This is done by dragging a plow along…
I figure the hard engineering challenge is the repeaters. How do you build repeaters and power them, considering you can't really service or replace them ever over the lifespan of the cable (the deep ocean bits anyway)? A repeater every 80km is a whole lotta repeaters.
Re: The Dunant subsea cable
#167Re: The Dunant subsea cable
#168This cable is not just to be used by Google right? Or am I misunderstanding something? Fundamentally, infrastructure should be publicly owned and then rented by companies to use it, in this case it seems like Google physically owns the cables and infrastructure which would be a massive waste.
Re: The Dunant subsea cable
#169Earlier quoted context omitted.
My bet is on tech like Starlink with inter-satellite communication. Starlink should have lower latency with space lasers compared to fiber.
Starlink satellites are in orbit 550km high. So any journey would add at least 1100km. Moreover not sure that a single satellite would be able to hit another one across transpacific distances and may need to go through multiple hops to get there. Each hop will add latency since signal needs regeneration. So it’s not clear to me a swarm of satellites is a real winner from a latency POV. Furthermore, given costs to put…
>> Starlink satellites are in orbit 550km high. So any journey would add at least 1100km
Might want to check with Pythagoras on that one..