Dynamic CAD sensitivity

[weebl2000]

Probe every 4 seconds to measure actual channel activity. If channel seems busy we adjust CAD to be less sensitive. If channel seems empty maximum CAD sensitivity.

Build here: https://mcimages.weebl.me/?commitId=dynamic-cad

Based on conversation in #1727 - this should make a busier node be less senitive to preambles. Tagging @recrof and @syssi would be interesting to see how this changes behavior.

You can use get cad and it will show stats for actual preambles detected during idle periods.

[usrflo]

@weebl2000 : I tested in my setup with 5 weakly connected nodes, 50 direct messages in 10s intervals, interference by a LoRa node sending local adverts every 6 seconds and a successful delivery counted if the last node ACKs.

Looks good: the problems I saw with 7c8e092 disappeared.

My results:

• cad off with this branch: 37/38 ACKs for 50 messages
• cad on with this branch: 39/40 ACKs for 50 messages
• cad on with this branch plus the latest dev commits: 42/36 ACKs for 50 messages

Attached you can find the monitoring logs.

dev-50-wo-cad.txt
dev-50-with-cad.txt
dev-50-wo-cad-2.txt
dev-50-with-cad-2.txt
dev-50-with-cad-latest-dev.txt
dev-50-with-cad-2-latest-dev.txt

[usrflo]

I wonder why using dynamic CAD together with repeated sending #2670 decreases deliverability significantly. Resending happens relatively often, but following nodes seem not to react. May the CAD analysis create too much deafness? I wonder why I didn't see this effect when running the same test without the sending repetition.

dyn-cad-on-rep.txt

[ignisf]

I've been running this for a while now on a companion in a network with 80+ repeaters in Sofia. I've noticed no ill-effects and I think it should be merged sooner rather than later to complement the release of CAD.

[Magalex2x14]

I've also been using this on my repeater since publishing. For now, I can only say that the repeater seems to have become more responsive, but flag 2 is still set quite quickly for 8 seconds CADFailMaxDuration (about 40 neighbors, 15-19 of them with positive SNR). I increase CADFailMaxDuration and observe. Raised it to 16 seconds (4->8->16) just now. CoreScope shows that in our network the packet propagation time reaches 20 seconds...