How does BLE devices update channel map?

[BOZHENG]

Dear All

I am right now working on BLE development with nRF52840DK. I checked a number of materials, including official specification from Bluetooth SIG, but none of them include information about how frequently BLE devices update their channel map.

So now my questions are as follow:

1. Do BLE devices update the channel map frequently?

2. Is there a fixed frequency for BLE devices updating the channel map?

3. If the updating procedure is based on environment, do we have a general guess for the intervals of channel map updating? Like in crowded environment, around every 20ms there will be an updating, in a normal environment, around 50-100ms there will be an updating?

Thanks in advance.

[shibshab]

1. It depends completely on the device. As far as I know, the specs does not dictate when it should be done, only how it can be done.
2. No, as stated above, it needs to be triggered explicitly by the device, and is not imposed by the spec.
3. There are several metrics that can be used. Some phones change channel map automatically when Wi-Fi is enabled. Other implementations can listen on certain channels to see if they are "congested" or not.