The 5G rollout has many components and one of them is the mesh of around 20.000 satellites that is planned. There are many stories about the role of the satellites and their capabilities, so we’ve made this summary of what we know so far.
What is planned
We know for sure that the following companies plan to launch a mesh of satellites:
At the time of writing we’ve only checked what SpaceX is up to so we’ll use them and their Starlink project in the following explanations.
Number of sattelites
The Starlink project has applied for permission to deploy 11,943 satellites in 2 different altitudes from the earth (“planes”) .
The application details can be viewed online here:
The paper we will use for reference in this post is the “Technical Attachment” which can be downloaded here: https://fcc.report/IBFS/SAT-LOA-20170301-00027/1190019.pdf
What the roles of the satellites aren’t
Lots of speculation is going into what these satellites will be used for and a common misunderstanding is that cell phones will communicate directly with them.
That’s not the case though and there are some good reasons for that.
First of all, the Starlink satellites will be hovering somewhere between 335 and 1325 kilometers from earth and even in the best conditions it will require a big antenna and a lot of power to communicate with something that far away.
Secondly, while a satellite can potentially cover a hughe area of several million square kilometers depending on several parameters, it can only serve a relatively small number of connections simultaneously.
What the roles of the satellites are
So instead of communicating directly with cell phones, the satellites will communicate with base stations on the ground which will then further relay to local antennas which will communicate with the individual cell phones.
In the cities this will be used to offload the landbased network when things get busy.
In remote areas it will be used to provide internet where this is not possible or feasible with normal land lines like fiber.
Another role of the satellites will be as so called “backhaul” where it will route connections on large distances quicker than the current landbased connections can do it today.
Have a look at this video to get more information about how that will work.
Please be aware that the satellites in this presentation have been made a lot bigger than they will actually be compared to the earth and so it appears in the video as if they take up much more space than they actually will.
Will satellites cover the entire earth in microwaves?
Well, not really, but it will cover a lot. Some of the time…
Ok, it’s complicated and we don’t have all the answers yet.
It gets even more so when we know that we’re only looking at one of several providers.
First of all, let’s clarify “coverage”
Traditional satellites like TV and GPS satellites spread out their signal to cover as large an area as possible and practical to serve as many users as possible with one-way signals.
5G satellites are different because they are able to stear their individual beams to the areas where the signals are needed.
The area which a satellite can reach with focused beams is called it’s “footprint”.
What we do know about the Starlink project
- The satellites are “non-geostationary” which means that they orbit around earth rather than staying in the same position relative to a position on earth
- The first badges of around 1,600 satellites will be spread over the majority of the earth including the North- and Southamerican continents (from 70 degrees north to 55 degrees south)
- The satellites will be evenly distributed over the area
- Subsequent badges will also spread over the earth, but in different planes (distance from earth)
- The satellites in the two planes can stear their beams in an angle of 87.9 and 102.18 degrees respectively in one direction
- The satellites in the two planes will operate with a beam angle of 1.5 degrees which will produce a beam size on earth of 550km2 and 52km2 respectively
- The satellites will communicate and transfer data between them with laser light
What we think we know
- Satellites send out short beacon signals all the time so that base stations can track them and request a connection
- From a glance, around half of the covered area is ocean (not very scientific, we know) where the satellites will only send beacon signals and not data, except when a ship requests a connection. This is important when assessing how much radiation will be sent to earth
What we don’t know yet
- How many beams can a single satellite send out simultaneously?
Coupled with the fact that the full capacity of the satellites will only be in effect when all sattelites have “clients” for their full capacity, it makes it pretty hard to estimate how much the satellites will actually be radiating over the earth.
However, as you can read in this post, the effect of each beam will be very weak.