The short answer would be for simplicity. It is odd to think of the access point as a dynamic moving object but in this case it is the only option that will work the way we want it to. Setting your two ground stations up as access points while the payload remains in station mode will absolutely not allow you to seamlessly transfer your stream from one ground station to another. You would find that if both ground stations could see the payload at the same time, only one ground station would have a connection to the payload at a time. Your payloads M5 modem would select either the first ground station it sees or chose the ground station with the strongest signal automatically. This would not be ideal as you would not be able to predict when your payload modem would switch to the other ground station. More likely, your payload M5 probably wouldn’t even connect to the other ground station until it can no longer communicate with the first modem it connected to. This would only create headaches and sorrow until the payload moves out of range from one of the ground stations. To explain why this would happen, we need to understand how networking (wired and wireless) connections work on a very basic level. Please forgive the oversimplification.
First, lets change names for easy tracking. The access point is now the “Master” and the station is the “Slave”. Each device must abide by a set of rules.
A master can never connect or directly communicate with another master.
A slave can never connect or directly communicate with another slave.
A master can connect to X amount of slaves. (Number depends on design)
A slave can only connect to one master at a time.
If a slave needs to communicate with another slave, that traffic must go through the master first and then sent from the master to the target slave. This protocol is also used by your standard home wifi connections. Your smartphone, computer, and tv are the slaves and your router or hub is the master.
So now we are left with a standard communication path that looks like this…
If we set up two ground stations as Access points and the payload as the station, we will have a situation where the payload will only communicate with one ground station.
If we set up one ground station as an Access point and the other ground station along with the payload are slaves, we will have a situation where both ground stations can communicate with the payload at the same time. (Slave ground station is not a direct communication.)
This is a problematic setup as both ground stations must maintain line of sight with each other in order for the slave ground station to receive communication from the payload. If the master ground station losses its connection with the payload, the slave ground station will also loose its connection to the payload.
Now if we have both ground stations set up as slaves and the payload set up as the master we have this setup.
Notice how both ground stations can independently connect to the payload regardless of the condition of the other ground station. This is why we have chosen to make the payload modem the master or in this case the Access point in our network and the ground stations as the slave.
We do have another mode at our disposal called “Access Point Repeater” that I intentionally ignored due to issues related to relativity. These modes don’t account for the repeaters moving in space very well. Networks that utilize these modes needs to have the Access point and Repeaters remain in “sync” with regards to latency times which would make it necessary to use GPS signals on every node to maintain uniform timing. Thats a different rabbit hole though...
As for the Access Point transmitting at a higher power level compared to the station mode, that is not accurate. All modes transmit at equal power levels unless the user adjusts it or you use different devices. If you are only using one ground station to connect to one payload, it does not matter which configuration you use as long as the basic “rules” are followed.
