Reducing single tower interference with ABAB configuration

I'm in a really noisy environment, so my choice of channels is sometimes rather limited.  Right now I have a tower with an ABAB configuration with A at 3660 and B at 4695, both on 10 MHz channels.

I'm finding the uplink in particular is really suffering in terms of S/N.  When I shut the cluster down and do a spectrum I'm not seeing noise from other towers, so I think it's self interference.  The noise levels basically lock me to my current channels, so I can't change to an ABAB configuration without dropping to 5 MHz.

Should I be enabling adjacent channel support for an ABAB config?  I'm worried that the loss in UL signal strength will cost me more than I gain in reduction in self interference.


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So I don't quite get what you're saying... you first say that you're in a really noisy environment... but then you go on to say that you run an SA and everything looks clean?

Can you post a screen shot of the AP SA? Have you run an SA on any of the clients, in particular the ones that seem to be having the most uplink issues?

What's the physical distance between the AP's in question? Are you using Cambium antennas? What do you have set for ATPC on the AP?

You don't need to enable adjacent channel support for ABAB config using the channel widths and channels you're using.

In this case, the noise limits me to those two frequencies.

Here is the spectrum for one of the APs.  This is with the entire cluster on the tower doing a spectrum so it doesn't show self interference.  Most of the SMs show very little noise; this tower is in a very heavily treed area so the trees block most of it on the downlink.  We have a few LOS or very close to LOS customers who see noise, but their signals are so strong it doesn't matter.

Each AP is on it's own mount about 4' away from the tower.  We're using Cambium 90 deg antennae.  ATPC is set to -60.

 Edit:  One company in the area is using Ubiquiti 36, and at least two others are using Alvarion 36.

Yeah, that SA doesn't look very good. I'd probably put A on 3660, and B on 3677.5. Use connectorized radios and 2' dishes for the people with the worst LOS and/or noise issues. Do some testing swapping channels between A and B and see if you have any better luck. If the other operator(s) using Alvarion are using 802.16e WiMAX, there may be a slim chance you could work with them and do some timing... PMP320 is WiMAX 802.16e and Cambium has some timing options with it and there's some white papers you can download that might give you some hints. If you're on good terms with the Ubiquiti user, find out what directions they point their sector(s) and see if they can start using shield kits if they haven't already. Might also be handy to buy a NSM365 off of eBay for scanning/testing help. You won't be able to time with the UBNT sectors at all.... again, if you're on good terms, you could work with them (and the Alvarion guys) to divvy up the spectrum. Not sure what other options you have... have you tried PMP450 2.4?