Frequency hopping with S132 v3

[AmiguelS]

Hello! I'd like to know if S132 v3 implements the frequency hopping scheme defined by BLE.

I've read some documentation on Gazell, but from what I understood, that is a completely different protocol, not a superset of BLE. I require BLE communication, so If my understanding is correct, Gazell is not an option.

[Wojtek]

Of course it does implement frequency hopping. You don't have to think about such a low layers - this (among other features) is what softdevice is written for. You can however control which channels are used for advertisements.

Yes, Gazell is something completely different.

[AmiguelS]

@wojtek I'm asking this because the behavior I'm seeing does not match what I expected to happen when frequency hopping is used. I may have the wrong idea though. I have two BLE devices and a strong Wi-Fi signal that overlaps some the of the BLE channels. What I observe is that sometimes I get huge interference from the Wi-Fi signal. This expected when the channels are overlapped. However, I expected the hopping to solve this issue by moving the BLE connection to a different channel, and that doesn't seem to be happening.

[endnode]

Well frequency hopping is kind of "dumb" property of BLE link layer on up to 37 channels used for PDU exchange during connection. You have right to exclude some channels if you suspect some interference there but this is not done automatically. Moreover embedded chips such as nRF5x don't have any specific indication of noisy channels so you can only try to observe and then use channel map functions of stack (SD) API... so you see initial channel map and hopping pattern in CONNECT_REQ (from GAP Central = master) and then only channel map can change. In the worst case you leave all 37 channels and during hopping patter some packets will drop but that's nothing serious until this will happen systematically on most of the channels for longer time. More about BLE frequency hopping (and BLE overall) here (slides 65-70 and 126-145).