QPSK MIMO-A

I've run into a situation I'm trying to understand.

I have three towers and five PMP450 (version 14.2) sectors that have had problems in the last two months.

In each case modulation had dropped to QPSK MIMO-A for all users on both upload and download.

All users had signal levels between -60 and -70 as well as SNR between 18 and 30.

The spectrum analyzer on each showed the noise floor at approximately -80.

Sometimes rebooting or power cycling restores service. Other times changing the center frequency up or down by 10Mhz brings things back to normal. 

Hi, 

Can you please post a screen capture of the AP->Tools->Link Status page when this issue happens. Also can you please perform LInk tests on a couple of these SMs and post those screenshots as well. Please enable SNR before running Link Tests. 

Also, what frequency band are you operating on?

Thanks,

Sriram

I've seen this happen with 3.65 AP's when there's an adjacent (but not inband) source of interference, which turned out to be UBNT running in the lower 25MHz. Rebooting usually solves it, or moving into the upper 25MHz (where UBNT isn't certified for), OR using a smaller channel width (10MHz) can help.

Next time I'll do some screen captures  and link tests.

Didn't run any link tests but complaints from users show ping times in the high hundreds of ms. 

I was suspecting side channel interference but was surprised not to see it in the spectrum analyzer.

Frequencies were 5800MHz and 5835MHz  Channel width 20MHz.  Towers were approx 15 miles  from each other with different facing sectors.