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Can you point me to your source on the planned constellation total switching bandwidth? I haven't read about that anywhere. I have read that they don't expect

Can you point me to your source on the planned constellation total switching bandwidth? I haven't read about that anywhere. I have read that they don't expect to be able to provide high levels of service in dense urban areas. Which does make me question the business model... I think you nailed it that the military and government will be a big customer. Iridium has ~1300ms+ latency and very low data rates, very high costs and the government is their largest customer from what I understand. Airlines are another likely market that would be a significant amount of business (post-covid19). If Starlink can compete against Iridium and the other existing satellite providers on price, they could at a minimum take most of that business.

foobiekr 6y ago
Per satellite max bandwitdh, per SpaceX, at commercialization will be a max of 17gbps [1, sorry for the lame source but it's what I could find at the moment]. Depending on how they're measuring that, the actual throughout could be substantially less than that. Given that their FCC filing was 20gbps per satellite, I think that's the raw, uncorrected bit rate, not the corrected bitrate which will be lower. A coworker and I did a back-of-envelope guess based on their power budget (switching capacity in bandwidth and pps and power are basically directly tied, ditto capacity and spectrum) and that's about what we arrived at as their upper bound (imho, not even half of that will be achievable). Note that this is a double-counted metric (bps total is bps_in+bps_out) for actual traffic volume. So let's go with that. The current SpaceX fantasy business model is to build out a constellation of 30,000 satellites, but near term not even close to that. Being very generous, let's credit them with an incredible 10k satellites, pretend they are not power constrained and use the full 20gbps allotted to them, and you get a total of 200k gbps total capacity for the constellation, uncorrected, assuming ample power, or on a good day 125Tbps for real data. Using a somewhat older core switch, the Juniper QFX10016, can do line rate switching for 480 100GE ports; 48Tbps in a single 21RU chassis from 2017. [2] These are commonly deployed in pops. The next generation will be doing that for 400GE ports in the same form factor, 192Tbps. A Cisco 8818, which is shipping right now, does 260Tbps per chassis in a 33RU form factor. The point is, anyone claiming we could serve even a large metro with a single one of these switches, let alone planet earth, would be laughed at, yet here we are. A given nation-scale network will have hundreds of routers with these kinds of capacities. I also don't think Starlink will get anywhere near the estimates I'm using here. [1] https://www.teslarati.com/spacex-starlink-satellite-upgrade-more-bandwidth-more-beams/ https://www.teslarati.com/spacex-starlink-satellite-upgrade-... [2] https://www.juniper.net/documentation/en_US/release-independent/junos/topics/topic-map/qfx10016-system-overview.html#power-supplies https://www.juniper.net/documentation/en_US/release-independ... [3] https://www.cisco.com/c/en/us/products/collateral/routers/8000-series-routers/datasheet-c78-742571.html https://www.cisco.com/c/en/us/products/collateral/routers/80... edit: moved the [2] to the right place. edit damage.
- jeffnappi 6y ago
  Thanks for the data points :) I think something to consider here is that there is an iterative development process taking place with the satellites. Given the stated lifespan of the satellites is 3-4 years, they likely expect to see additional innovation over time and are gambling that the network will be improved over time, and may one day actually be capable of serving urban areas. This seems like a wise approach and appears to work well for both SpaceX and Tesla. The most viable use case in the near term is clearly to serve remote and rural areas which is admittedly a small market. There is a chance you might see governments subsidize service to rural areas that are underserved. I also imagine there will be a number of marine and aviation customers - though that's likely even smaller than the rural market. But yeah, I'm not one of the people who will claim it will serve urban markets any time soon... That's rediculous - as rediculous as saying Tesla will achieve level 5 autonomous driving this decade
  - foobiekr 6y ago
    I don't think the iterative nature actually helps SpaceX. Whatever use case they're targeting, and like I said, I don't know, and would like to know, isn't likely to be made more viable by bandwidth that changes substantially by the hour, and the total cost of getting a satellite into orbit makes generational turnover doubly challenging. I just do not get the business model. It makes no sense for commercial internet access, even in rural areas. I think perhaps temporary access in undeveloped areas, where the total capex is lower than that needed for a temporary LTE deployment, for example, might be it, but that is not a big market.
    - jeffnappi 6y ago
      I guess we'll see if they can pull a rabbit out of a hat. A lot of folks didn't think battery electric cars were going to be possible either. And... Landing freaking rockets on barges in the ocean? I'm no fan boy, but I'm also not going to be a naysayer on this one. Starlink lets SpaceX make use of cores with long launch records that others may not be willing to risk their payloads on, and SpaceX can also use those launches to test other risky maneuvers. So... Perhaps there's some other value in Starlink that we're not privy to.

foobiekr 6y ago

Per satellite max bandwitdh, per SpaceX, at commercialization will be a max of 17gbps [1, sorry for the lame source but it's what I could find at the moment]. Depending on how they're measuring that, the actual throughout could be substantially less than that. Given that their FCC filing was 20gbps per satellite, I think that's the raw, uncorrected bit rate, not the corrected bitrate which will be lower. A coworker and I did a back-of-envelope guess based on their power budget (switching capacity in bandwidth and pps and power are basically directly tied, ditto capacity and spectrum) and that's about what we arrived at as their upper bound (imho, not even half of that will be achievable). Note that this is a double-counted metric (bps total is bps_in+bps_out) for actual traffic volume. So let's go with that. The current SpaceX fantasy business model is to build out a constellation of 30,000 satellites, but near term not even close to that. Being very generous, let's credit them with an incredible 10k satellites, pretend they are not power constrained and use the full 20gbps allotted to them, and you get a total of 200k gbps total capacity for the constellation, uncorrected, assuming ample power, or on a good day 125Tbps for real data. Using a somewhat older core switch, the Juniper QFX10016, can do line rate switching for 480 100GE ports; 48Tbps in a single 21RU chassis from 2017. [2] These are commonly deployed in pops. The next generation will be doing that for 400GE ports in the same form factor, 192Tbps. A Cisco 8818, which is shipping right now, does 260Tbps per chassis in a 33RU form factor. The point is, anyone claiming we could serve even a large metro with a single one of these switches, let alone planet earth, would be laughed at, yet here we are. A given nation-scale network will have hundreds of routers with these kinds of capacities. I also don't think Starlink will get anywhere near the estimates I'm using here. [1] https://www.teslarati.com/spacex-starlink-satellite-upgrade-more-bandwidth-more-beams/ https://www.teslarati.com/spacex-starlink-satellite-upgrade-... [2] https://www.juniper.net/documentation/en_US/release-independent/junos/topics/topic-map/qfx10016-system-overview.html#power-supplies https://www.juniper.net/documentation/en_US/release-independ... [3] https://www.cisco.com/c/en/us/products/collateral/routers/8000-series-routers/datasheet-c78-742571.html https://www.cisco.com/c/en/us/products/collateral/routers/80... edit: moved the [2] to the right place. edit damage.

jeffnappi 6y ago
Thanks for the data points :) I think something to consider here is that there is an iterative development process taking place with the satellites. Given the stated lifespan of the satellites is 3-4 years, they likely expect to see additional innovation over time and are gambling that the network will be improved over time, and may one day actually be capable of serving urban areas. This seems like a wise approach and appears to work well for both SpaceX and Tesla. The most viable use case in the near term is clearly to serve remote and rural areas which is admittedly a small market. There is a chance you might see governments subsidize service to rural areas that are underserved. I also imagine there will be a number of marine and aviation customers - though that's likely even smaller than the rural market. But yeah, I'm not one of the people who will claim it will serve urban markets any time soon... That's rediculous - as rediculous as saying Tesla will achieve level 5 autonomous driving this decade
- foobiekr 6y ago
  I don't think the iterative nature actually helps SpaceX. Whatever use case they're targeting, and like I said, I don't know, and would like to know, isn't likely to be made more viable by bandwidth that changes substantially by the hour, and the total cost of getting a satellite into orbit makes generational turnover doubly challenging. I just do not get the business model. It makes no sense for commercial internet access, even in rural areas. I think perhaps temporary access in undeveloped areas, where the total capex is lower than that needed for a temporary LTE deployment, for example, might be it, but that is not a big market.
  - jeffnappi 6y ago
    I guess we'll see if they can pull a rabbit out of a hat. A lot of folks didn't think battery electric cars were going to be possible either. And... Landing freaking rockets on barges in the ocean? I'm no fan boy, but I'm also not going to be a naysayer on this one. Starlink lets SpaceX make use of cores with long launch records that others may not be willing to risk their payloads on, and SpaceX can also use those launches to test other risky maneuvers. So... Perhaps there's some other value in Starlink that we're not privy to.