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Provisioning DFS Channels in US

Posted: Sun Oct 06, 2019 2:02 am
by Mauronic
Hi,

I am trying to utilize DFS channels on a Mikrotik Groove 52 because 36 - 48 and 149 - 165 are very crowded in the US urban areas where I need to provision service.

From my tests around various locations, it seems that a lot of consumer mesh routers are being sold. They are taking very large amounts of bandwidth at the low and high end of the spectrum for wireless mesh backhaul between nodes. 2.4Ghz is already crowded, so it's very challenging.

What are people doing about this?

Also, I am interested in getting more information about DFS from the router. I have seen the "radar detected" on the status after manually choosing a channel but I can't find any other information.

1) Can you see when the last radar scan was done?
2) Can you see when the next radar scan will be done?
3) Can you see a list of channels that were blocked due to radar scanning?
4) What are the chances that a DFS channel may become unavailable later? If it is, what happens?

Re: Provisioning DFS Channels in US

Posted: Wed Oct 09, 2019 10:13 am
by WeWiNet
+1

- adding a radar detection counter indicating number of detections since up time!
- specific DFS/radar logging!

Audience for example wlan3 interface is offering only DFS 4x4 Wifi channels (limited to channel 100 and above ) and knowing how/when radar is detected and what backup is
available (other pre-scanned channels?) is a must to use it correctly.

Re: Provisioning DFS Channels in US

Posted: Wed Oct 09, 2019 11:49 am
by pe1chl
Indeed there should be a lot more log and/or status information for DFS events.
As it is now, it often misdetects RADAR on our APs (detecting RADAR where there sure isn't any) and it is impossible to debug it because no details are being logged.
1) Can you see when the last radar scan was done?
2) Can you see when the next radar scan will be done?
It does not work like that. There is some hardware that detects pulses and conveys this information to the software, and the software decides if the pulses are RADAR or not, and what to do.
This is happening all the time.
3) Can you see a list of channels that were blocked due to radar scanning?
Unfortunately, no. You can only see the DFS messages in the log (with timestamp) and thus you can know when the vacated channel is available again (according to local regulation selected by country code, or hardwired in the USA).
[4) What are the chances that a DFS channel may become unavailable later? If it is, what happens?
There are 3 situations:
- actual RADAR installed locally. will be detected all the time
- RADAR at some distance that is only detected under suitable tropospheric conditions that extend its radio range (temperature inversion, high pressure area). this will go away once the weather changes.
- invalid detection of RADAR due to hardware and software limitations or defects. e.g. sometimes RADAR is detected when certain cellphones are nearby, or when a RADAR on another channel is so local and thus so strong that it overwhelms the receiver and causes misdetection at other channels. this can be permanent of vary a bit, depending on levels.