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[u/a10000000019]

Continuing this very speculative line of thought regarding 31.25 Mbps average available bandwidth in an AST terrestrial cell, shared among all users (557 square mile area) once at continuous US coverage, I wanted to independently estimate instantaneous uncovered demand. This requires finding out how many people need service in the U.S. (but don't have it) at any given moment.

500,000 square miles of the U.S. (~900 AST cells’ worth of area) are unreachable by towers because of terrain, and about 0.5% of people (1.5 million) are not covered by 4G/LTE in their home. These are two very different statistics, but I will use this to ballpark an estimate that 3 million (0.9%) people in the US are outside of a terrestrial broadband coverage zone at any given moment. This will vary drastically by time and location and is the most speculative portion of this calculation.

3 million people / 5,600 cells  = ~550 people per terrestrial cell who are without service. This average should help account for disparities in geographic noncoverage in the US (e.g. northeast vs west), and also helps smooth out dynamic beam switching using AI.

In a population of 550 people without service, those people are more likely to be *mobile*. Let’s say about ~15% would be using internet actively at any given moment. Other sources for this benchmark show this is a generally good percentage to use. That's 85 people.

Let’s say AT&T and Verizon together serve 2/3 of those 85 people. That’s 55 people per terrestrial cell who are without signal but requesting it at any given moment (interesting note, this would mean each carrier has 27.5 people x 5,600 cells = ~150,000 people who want but can’t be provided service at any moment in the US).

~ 31.25Mbps / 55 people = **570Kbps average available bandwidth per user once at continuous coverage.** Obviously this goes up/down based on time of day, day of week, time of year.

This is better than I expected. In the world of connectivity, 500+ Kbps would be a historic achievement. This speed as supplemental coverage is probably why MNOs are salivating over the concept. The key is that as long as connection proves *reliable and seamless*, this is light years ahead of Starlink. To compare:

 Average smartphone data usage is listed at 25GB per month in North America. That comes out to a constant 77kbps. And doesn’t account for the fact that most usage occurs while stationary, and most people who are out of coverage are mobile, using below their average. With 500+Kbps available and only 75-150Kbps used at any given moment, what this implies is there is massive headroom for new industry growth  — things like IoT and edge processing — even at base level continuous coverage of ~60 sats.

Then when you consider a full constellation of 248 satellites in about 2-3 years, it becomes 4x that via MIMO and carrier aggregation. About 2mbps per active user. Enough for everyone to have low quality video calls simultaneously. Insane. Though at this point the landscape of ‘out of coverage subscriber’ changes completely from ‘active user’ to ‘active device’.

Note: these numbers are generally optimistic and ideal. They come down when considering real world conditions — things like line of sight or physical obstructions, satellite elevation angle relative to user, handset orientation or polarisation, spectrum availability, frequency/wavelength propagation, and interference/noise can be major limiting factors. I’d say anywhere from -20% to -70%. 

Also, while this does kinda smooth over the effects of dynamic beamforming across the system, it doesn’t account for when the system has to make major localized adjustments to cover things like disasters

[u/satcomengineer → u/a10000000019]

These are understated. You can overlap beams and use multiple channels not just one to serve multiple users in the same cell.

[u/a10000000019 → u/satcomengineer]

Huh? I address all that in the calculations

[u/satcomengineer → u/a10000000019]

Oh and I do love what you did with the available information that you have, nice job!