Starlink – Let’s Play With Numbers

Internet access over Starlink is definitely an interesting topic and has me captivated ever since first reports appeared of individuals who got themselves a dish when the public beta test first started in 2020. While their reports are often impressive, there is relatively little information of the overall capacity of the system today and its potential in the future. But when digging a bit deeper, some interesting numbers can be found.

In October 2021, the IEEE published a paper by Ogutu B. Osoro and Edward J. Oughton tittled ‘A Techno-Economic Framework for Satellite Networks Applied to Low Earth Orbit Constellations: Assessing Starlink, OneWeb and Kuiper‘. The PDF version is freely available. It’s a fascinating read and I leave it to you to explore their calculations on how many subscribers are required to get a return of investment on the billions of dollars spent on the system already and in the future. In this post, I’m rather more interested in the overall system capacity and what this means in practice. Starlink keeps shooting new satellites into orbit on a regular basis, and according to Wikipedia, there are 2700 satellites in orbit as of July 2022. That is an extraordinary number and according to the paper, each satellite has a downlink capacity of 11 Gbps. The theoretical maximum seems to be higher, but I’ll stick with this number for now, as it takes a lot of real world variables into account.

Still, 11 Gbps sounds like a lot, and compared to single geosynchronous satellites, it definitely is. But the world is a big place, so things get ‘relative’ quite quickly. The paper has analyzed system capacity with 5000 satellites in orbit, so about twice the number currently in operation. Even with the higher number, each satellite has to cover an area of 101.000 km2 (based on equal distribution, which they are not quite). For comparison: Germany covers an area of 357.000 km2. In other words, in the 5000 satellite constellation, ‘only’ about 3.5 satellites cover all of Germany at any one time. In other words, that’s a total capacity of 38 Gbps. Still sounds like a lot? Yes, but a lot of people live in the area.

The authors then calculated the per-user throughput. At a user density of 0,1 users per km2 and an overbooking factor of 20 during busy hour, the resulting downlink data rate is 24 Mbps. Oh!? Not bad for today, but its not a stellar number anymore. And 0,1 users per km2 means that users need to be on average in an area 6 km away from each other. I guess you can see where this is going. For Germany with 85 million inhabitants, that means that only 35.000 can use Starlink in Germany before the resulting throughput during busy hour falls below those 24 Mbps. Today, with only half the number of satellites deployed, the number will be even smaller. That’s a rather low number.

In other words, Starlink definitely can’t compete with terrestrial fixed line and not even with mobile network capacity. But what they can obviously do is bring high speed Internet to underserved places. The question then is, from a European perspective, if this will be enough?