3 ms·
I explain it this way; think of it as a cellular network in the sky, except in a terrestrial cellular network, the cell sites are stationary and connected via f
by zw123456 4y ago
I explain it this way; think of it as a cellular network in the sky, except in a terrestrial cellular network, the cell sites are stationary and connected via fiber and you are moving in your car or walking (or you can). With LEOS, each satellite is like a cell site, like a 5G one with phased array antennas, the satellite is moving and you are stationary and the satellited are connected to each other via free space optics but the backhaul is obviously RF, but the hand offs between satellites is over FSO. In fact, R17 of 3GPP standards now has provisions in it for 5G direct from the LEOS to the user. None deploy yet. but in a couple of years, that could be interesting.
Each satellite paints a spot on the ground using the beamforming capabilities of the phased array antenna. The capacity of that spot is of course limited by Shannon limit, where
C ~ B * S
C = capacity (think Mbps)
B = spectrum (think Mhz)
S = SINR (Singal to noise ratio)
If you have a smaller spot on the ground, then the spectrum is shared amoung fewer users. If you have more powerful transmitters and or better antennas, then your C will be better.
Right now based on the specifications I have seen publicly, Amazon's Kuiper (their LEOS) will have higher capacity than starlink because it will have half the "spot" diameter. That is due to better antennas mostly, more array elements mean narrower beam width.
- AtlasBarfed 4y agoYeah, but starlink can just cycle in newer generation satellites with tighter beams as well, could they not? Is there a technical reason I'm not aware of that they can't? Would Dishys even need to be changed? Kuiper needs Blue Origin to get cost competitive with SpaceX, which doesn't look likely because a) they don't even have commercial operations and b) uhoh, here comes Starship. Sure SpaceX might launch Kuiper satellites ... at a premium over Starlink.
- ncmncm 4y agoDishys only need to focus on the right satellite.
- zw123456 4y agoYes, but it's tricky and takes time, if you replace on starlink with 30km radius with 4 at 15km. but then kupier could go to 10km while starlink is doing that. Satellite wars!
- AtlasBarfed 4y agoKuiper needs to get off the ground, no idea what their timeline is but... yeah. Hm, they were supposed to launch two satellites in 2021, now that's pushed to Dec 2022. They "announced" 83 launches with way-more-expensive than SpaceX and fictitious New Glenn launches. Blue Origin has been way way way behind its estimates. ... Kuiper has Bezos money behind it, but we'll see. Starlink is already up, and if Starship launches, I doubt anyone but SpaceX can compete. Elon the prognosticator says 1-12 months for first starship launch. Even if it's two years, Starship likely becomes operational before even a minimal Kuiper flotilla. But, competition is good, so even if that happens, I hope Bezos keeps the money flowing.