Hi,
In order to increase the TX duty cycle, AFA & LBT can be used in most cases for the 863 to 870 MHz ISM band. However, in the 869,400 MHz to 869,650 MHz g3 band (500 mW), the duty cycle limit is 10% which is 360 sec in one hour (if not using LBT+AFA). But if you choose to use LBT & AFA, the duty cycle will actually decrease! The maximum on time for AFA+LBT is 100 sec in any 200 kHz spectrum (which basically means the whole sub g3 band).
This is what I find a bit confusing. If your system is "polite" and uses LBT and you implement AFA (changing channels), you will have less TX on-time compared to if you use a single channel with no LBT... One intention with using LBT+AFA is to allow a greater duty cycle - which is normally the case for the rest of the ISM band.
So my question is: would it be possible to use LBT and AFA but with the 10% duty cycle definition for this sub 3g band?
Argument1: I guess when it comes to LBT, no one could blame you for being "polite" and use LBT - the device can transmit anyway whenever it wants.
Argument2: But, when using AFA, you actually change channels. The question is whether the duty cycle limitation (as apposed to the AFA+LBT) imposed by the EN 300.220 actually refers to single channel devices.
One could also imagine a system which has just AFA (no LBT). Then I guess the duty cycle limit applies (normally the stricter rule). So combining this with argument1 I guess one should be allowed to apply the normally "stricter" duty cycle rule which turns out to be a better option while still implementing LBT and AFA if one chooses to do so anyway.
Anyone who has any insight to this special case?
Regards