5.4 GHz AP Cluster Recommended Channels

stjoewireless · December 4, 2015, 4:41pm

We use PMP 100 units and have clusters on 9 separate towers. We are using frequencies all over the the 5.4 spectrum. This was set up many years ago and it seems like it is a constant battle with DFS detections and one tower possibly interfering with another. Not to mention it is a nightmare to expand on another neighboring tower.

These issues turned me to the User Guide for the PMP 100s. There is a section that talks about the Clusters Recommended channels.

The fully populated cluster requires only three channels, each reused by the module that is mounted 180° opposed. In this frequency band range, the possible sets of three non-overlapping channels are numerous. As many as 11 non-overlapping 20 MHz wide channels are available for 1X operation. Fewer 25 MHz wide channels are available for 2X operation, where this greater separation is recommended for interference avoidance.

This information is also repeated when going through the quickstart guide on an AP.

Has anyone had success with this method and if so how does the unit handle DFS detections. The guide make it clear for sharing the frequency the opposite sector but it does not mention anything about the alternate frequency 1 and 2.

I'm just trying to find a way to clean up our deployment and possibly make it a little more stable. We have to go through all the time to look for DFS detections because for example a DFS detection on a N sector will cause issues with a customer connected to the SE sector.

It's just a nightmare having 48 sectors with each sector needed at least 2 Frequencies. The way they are setup now it just feels like it was not panned out very well.

I will attach a to scale map of our access point locations and their sectors. I have put in the hexagon sectors like the guide shows with the ABC sectors being mirrored. Like I said though our network right now is not set up to mirror the opposite sector. It is setup with the idea of APs on separate towers pointing at each other and not being on the same Frequency.

Ted_Stewart · December 10, 2015, 11:24pm

I gave kudos just for the detailed diagram, but since nobody else has taken a crack at this...

I've had similar problems with 900, where I've only got space for three channels at once. I've never used a 5.4 PMP100, so there may be limitations I'm not aware of.

With the 320s, I found alternating ABAB and CDCD on towers worked a lot better than having ABCD on each. From what I'm seeing in the user guide, you've can fit a lot of different channels in that frequency range, so alternating ABCABC and DEFDEF should be possible. I suppose you could also try ABCDEF for all towers as well, but that tends to lead to SMs seeing multiple towers pointing their way.

If that isn't possible, you can try an ABABAB configuration instead. It allows you to avoid a particularly problematic source of noise, if channel C is really jammed out at a given tower. Witha full cluster, the self interference tends to be a problem, but with clusters missing an AP or two that is mitigated. Sites 7 and 9 look to me like excellent canditates to give it a try.

I think you definitely have some options there, it really depends on what your noise conditions are like.