SAS assigning channels on top of you?

We converted a PMP 450 network in rural TX from Part 90 to Part 96 and it worked very well at first. Just in the past few days, we have been getting subscriber complaints of low speeds and disconnects.  This morning we did a spectrum scan and was somewhat surprised to find the new CBRS allocation of 100 MHz was pretty much full across the band - and again this is a rural area.    The first scan is for an AP with a grant of 3580 showing energy for the frequencies it was granted by the SAS.  We moved it to the 3620 slot and got a new grant and it is working ok.

The second scan is from another AP taken today (Thurs 4/9) 

What concerns us is that our AP #10 / AP #12 which are back to back on the same tower (PMP 450 with external Cambium sector antennas)  were both granted a 20 MHz channel at 3580 during our initial conversion to CBRS and had a pretty clean spectrum. 

Now, we see what appears to be strong signals from other operators on top of the spectrum we were granted by the SAS.  

Are we not understanding how the SAS works?   Is there any method to query the SAS directly and find out where the other grants may be located in relation to this location?  

We moved to CBRS in this location as soon as it was open because the 3650-3700 band was a wild-wild-west of unregistered operators dropping old 365 gear everywhere and oil companies camped on various channels who flat out  refused to even answer a phone call on frequency coordination.  

Any comments or suggestions would be welcome. Thanks.

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This issue may pop up in some spots where multiple operators are establishing a CBRS presence in close proximity to one another.    As you point out, working out any kind of frequency coordination can be a challenge if neighboring operators do not wish to cooperate.   Unfortunately, as with voice over IP systems,  if no admission control or quality of service capabilities are put in place, one call over the capacity of a given link can ruin voice quality for everyone.

To this (very early) point in the evolution of CBRS, the primary job of the SAS has been to protect incumbents - if SAS operators could not do that, CBRS would never have been certified.   Since that hurdle has been cleared, SAS operators have been focusing on the problem of managing operator to operator interference - aka coexistence. 

Solutions are on the way.

yes, we have seen this sort of thing also. And in a DPA area. This is a GIANT MESS!!!!!

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It seems to vary by location.   I agree that there's been in my opinion some over-optimistic expectations from operators on how well the SAS works.   The training that I took from Federated certainly did not even hint at the fact that the production SAS didn't have many of the capabilities stated.

Our customers who were getting hammered by rogue operators in the old band  - don't get me started - were

looking to CBRS to at least give them some relief.    Did not happen.

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