3 ms·

> There's no way that wireless links will ever be faster than backbone fiber - the whole notion makes very little sense. Why? Wireless signals propagate faster

by ethbro 7y ago

> There's no way that wireless links will ever be faster than backbone fiber - the whole notion makes very little sense. Why? Wireless signals propagate faster linearly than fiber signals, no? I don't have time to do napkin math, but if 2x orbital height + curvature path multiple < linear speed difference, wireless comes out ahead. From memory, I think this held true for transoceanic distances.

LMYahooTFY 7y ago
So is the high latency reputation from satellite links just due to low end hardware on the satellite?
- NOT_JON 7y ago
  Typical satellites are at geostationary orbit (35,786km). Starlink satellites will be at 340km/550km/1150km. Lower orbits = less latency, but require a lot more satellites to cover the same area.
- jws 7y ago
  Traditional satellite internet providers used satellites in geosynchronous orbit (that whole “aiming your dish” thing). That’s a 270ms hop up and another back. Starlink is the other “not here yet” services are going to use low earth orbits for something like a 25-35ms latency to the satellite.
- MayeulC 7y ago
  No, typical communication satellites operate in geostationary orbit, 36,000 km high. Signal must go up that far, then down again. The earth's circumference is 40,000 km, so you've traveled more already (and yet, are still in the same area because I didn't count transmitting to another satellite -- which AFAIK is never done: the satellite transmits back down to somewhere where the data can be transmitted trough fiber). Assuming light travels at 2c/3 in fiber, it would still take less time for a signal to go around the equator back to the same spot than for it to arrive anywhere on earth if using a satellite link. Spacex's satellites are a game-changer because they sit in low orbit.
walrus01 7y ago
The bandwidth available for a single DWDM channel in fiber is multiple terahertz wide.
- ethbro 7y ago
  I sort of assumed parent was using "fast" in terms of throughput rather than speed, but wanted to clarify.

by ethbro 7y ago

LMYahooTFY 7y ago

So is the high latency reputation from satellite links just due to low end hardware on the satellite?

NOT_JON 7y ago
Typical satellites are at geostationary orbit (35,786km). Starlink satellites will be at 340km/550km/1150km. Lower orbits = less latency, but require a lot more satellites to cover the same area.
jws 7y ago
Traditional satellite internet providers used satellites in geosynchronous orbit (that whole “aiming your dish” thing). That’s a 270ms hop up and another back. Starlink is the other “not here yet” services are going to use low earth orbits for something like a 25-35ms latency to the satellite.
MayeulC 7y ago
No, typical communication satellites operate in geostationary orbit, 36,000 km high. Signal must go up that far, then down again. The earth's circumference is 40,000 km, so you've traveled more already (and yet, are still in the same area because I didn't count transmitting to another satellite -- which AFAIK is never done: the satellite transmits back down to somewhere where the data can be transmitted trough fiber). Assuming light travels at 2c/3 in fiber, it would still take less time for a signal to go around the equator back to the same spot than for it to arrive anywhere on earth if using a satellite link. Spacex's satellites are a game-changer because they sit in low orbit.

walrus01 7y ago

The bandwidth available for a single DWDM channel in fiber is multiple terahertz wide.

ethbro 7y ago
I sort of assumed parent was using "fast" in terms of throughput rather than speed, but wanted to clarify.