Traditional satellite internet uses satellites in geostationary orbits, or 35,786km high above the equator. This is great because satellites in that orbit are stationary relative to the ground, so you just need a parabolic antenna pointed at a specific point in the sky to get great reception. But it's also terrible for latency because the signal takes 120ms just to get up, and another 120ms to get down. Assuming you live on the equator, directly underneath the satellite. For someone living in the temperate regions, typical real rtts are in the 700ms area.
Starlink and OneWeb are different in that they intend to use a lot of satellites in low orbits to maintain constant coverage. This is technically much harder, not the least because you need thousands of satellites to get reasonably good coverage, but also because the ground station and the satellite transceiver both need to track each other. This was not technically feasible before, but modern AESA antennas can steer their signal without having to move the antenna, and can both transmit and receive multiple simultaneous beams and very rapidly move the beams around when doing time-sharing.
The minimum round-trip time to something very close to you and also close to it's own ground station will be on the order of 10ms. However, where the system really shines is long distance communication. The satellites will pass the signal between each other using lasers, and will get the signal to the other side of the earth much faster than terrestrial fiber, both because laser in vacuum travels substantially faster than one in fibre, and also because the fibres don't get to follow ideal great circle paths.
Independent researches have evaluated the likely latencies of the system, and the results are frankly shocking. For example, today on the existing fiber network, rtt between London and Singapore is ~160ms. On Starlink, the rtt will be ~90ms.
Starlink and OneWeb are different in that they intend to use a lot of satellites in low orbits to maintain constant coverage. This is technically much harder, not the least because you need thousands of satellites to get reasonably good coverage, but also because the ground station and the satellite transceiver both need to track each other. This was not technically feasible before, but modern AESA antennas can steer their signal without having to move the antenna, and can both transmit and receive multiple simultaneous beams and very rapidly move the beams around when doing time-sharing.
The minimum round-trip time to something very close to you and also close to it's own ground station will be on the order of 10ms. However, where the system really shines is long distance communication. The satellites will pass the signal between each other using lasers, and will get the signal to the other side of the earth much faster than terrestrial fiber, both because laser in vacuum travels substantially faster than one in fibre, and also because the fibres don't get to follow ideal great circle paths.
Independent researches have evaluated the likely latencies of the system, and the results are frankly shocking. For example, today on the existing fiber network, rtt between London and Singapore is ~160ms. On Starlink, the rtt will be ~90ms.