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Comment by sandworm101 | Hacker News Reader

Low-bandwidth/low-latency people tend to also demand high reliability and consistency. A low-orbit satellite network might be fast but, because sats move to quickly, cannot be consistent in that speed. Sats also won't ever connect data centers other than perhaps for administrative stuff. The bandwidth/reliability/growth potential just isn't there compared to bundles of traditional fiber.

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> Low-bandwidth/low-latency people tend to also demand high reliability and consistency.

For trading applications, people will absolutely pay for a service that is hard down 75% of the time and has 50% packet loss the rest, but saves a millisecond over the fastest reliable line. Because otherwise someone else will be faster than you when the service is working.

They can get reliability and consistency with a redundant slower line.

Can you provide a source to this statement? The redundancy needed to transmit at desirable reliability with 50 % packet loss would, I imagine, very quickly eat into any millisecond gains -- even with theoretically optimal coding.

Someone more familiar with Shannon than I could probably quickly back-of-the-napkin this.

Traders wouldn't use redundancy etc. Whenever a packet with info arrives, they would trade on that info (eg. "$MSFT stock is about to go down, so buy before it drops!"). If there is packet loss, then some info is lost, and therefore some profitable trading opportunities are missed. But thats okay.

There are thousands of such opportunities each second - they can come from consumer 'order flow' - ie. information that someone would like to buy a stock tells you the price will slightly rise, so go buy ahead of them and sell after them in some remote location.

There is also a market for stocks that trade on different exchanges, resulting in fleeting differences in price between exchanges. Those who learn of price moves first can take advantage of such differences. In such cases, all you need to transmit is the current stock price. The local machine can then decide to buy or sell.

Financial companies have taken and upgraded/invested in microwave links because they can be comparatively economical to get "as the crow flies" distances between sites:

https://www.latimes.com/business/la-fi-high-speed-trading-20...

https://arstechnica.com/information-technology/2016/11/priva...

https://en.wikipedia.org/wiki/TD-2#Reemergence

I'm not sure about the high packet loss statement, but it wouldn't suprise me that it's true if the latency is lower enough to get to take advantage of arbitrage opportunities often enough to justify the cost.

There's definitely a few billion a year in revenue for Starlink if they sell very low latency, medium bandwidth connections between Asia, the US, Europe and Australia to trading firms. Even if the reliability is much worse than fiber.

Starlink latencies sadly aren't competitive due to the routing paths it uses. And sadly there are currently no competitors to starlink.

The routing paths traveling via ground stations, you mean? My understanding is that they were experimenting with improvements to this, they just haven't deployed anything yet.

No, even with proposed inter-satellite routing paths, they are too slow. The trading industry has very much done the math on this.

The comparison is against radio and hollow-core fiber, not conventional fiber.

Laser links between satellites have been active since late 2022, or was there some additional improvement you're referring to?

I haven't kept track of that, but there is no other improvement. Even with the straightest possible laser links in space, they are too slow.

A radio will beat starlink on ping times. Even a simple ham bouncing a off the ionosphere can win out over an orbiting satellite, at least for the very small amounts of data needed for a trade order. The difficulty in such schemes is reliability, which can be hit-or-miss depending on a hundred factors.

> sats move to quickly, cannot be consistent

Satellites in geostationary orbit are a (very common) thing.

Geostationary is so much further than LEO though so worse latency

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