Lastest CBRS DPA weirdness

OK, we have a full circle of PMP450M APs on a water tank in Rockingham NC with a scattering of PMP450b clients. ABAB frequency reuse, four 10MHz PAL channels utilized in pairs for two 20MHz wide channels. One AP aims south (azimuth 180) and was booted by DPA events (East11,East12, min 95 miles away from tank) on June 8th from one-half of its usual 20MHz wide PAL channel. So it rebooted itself and set itself to a 10MHz wide channel on the remaining half that had NOT been affected by the DPA. Clients reconnected and service continued. Perfect.(ish)

The opposing AP aiming north (azimuth 0) on the same channel (3580-3600) was NOT impacted by the same event. HOWEVER, the single client off of it WAS impacted. Because it was the client end device (PMP450b) and not the AP end device, the sector did NOT reboot and adjust itself to accommodate, and the client (county historical society) was out of service all day until the series of DPA move events concluded.

I would have expected/hoped that the sector would have been able to adjust itself to accommodate the required change in order for the clients to continue operating. The frequency and duration of DPA events is quickly leading us to avoid deploying CBRS equipment, particularly when the equipment turns out to not be able to adapt as needed to continue running.


So nobody else has seen this? Or is everyone just abandoning this equipment/spectrum? So far it seems to me like a huge waste of money/time/effort obtaining PAL channels (4@10MHz in each of 8 counties) when we can do everything “right” and still lose customers when service randomly cuts out for hours on end due to DPA events.

I’ve also observed occasions where both 10MHz-wide grants are suspended due to DPA, and the AP will just sit there with no clients connected and wait for the event to clear - it never seems to attempt to find another channel.

Just realized I’d not mentioned yet, we’re running 20.2.1 firmware all around.


Good Day, I have been down your path and currently am seeing minor issues. Who is your current SAS provider?

We are using Google as SAS.


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Curious where you find what sensor detects that and where its located?

With Google as our SAS I log into and select the radio, then ‘History’ tab lets you view the history of activity. If you download this data the CSV spreadsheet includes more detail, including notation of what DPA(s) triggered.


Due to the sensitive nature of these events (i.e. DPA is presumably triggered to protect US Naval radar activity), the exact sensor location or exactly which frequencies are triggered will not be revealed. As newkirk states, some of the SAS Administrators will show history of DPA activation, giving the area that was affected and when.