Self-interference - How close is too close?

Hi everybody,

I’m trying to figure out how to keep a full cluster of APs and a single AP located a mile (or less) away, from interfering with each other (or figure out if they even will interfere with each other).

In the manual, it talks about maintaining “the same frequencies in the same sectors for all clusters in the network” i.e. north and south on every cluster will be one frequency, northeast and southeast another frequency, and northwest and southwest yet another frequency. But what about when there is only 1 full cluster and 1 remote AP? Should I keep that single AP’s sector frequency the same as the cluster’s. Say the single AP is facing North, should I make it the same frequency as the North AP in the cluster? Also, because they’re so close in distance, do I need to turn on transmit frame spreading? Are there any other settings I need to be aware of to avoid interference? Power down maybe? I know that the color code will help separate which of my SMs register to which AP.

The single AP will not be synchronized with the other cluster’s CMM. All of the APs are in the 5.2 GHz range, if that matters in this scenario. Also, there isn’t any other 5.2 interference in my area. I’m just not sure if I’ll be interfering with myself. Thanks for any advice you can give. The equipment is already in place, I’m just trying to be prepared for when we actually boot these things up.


Canopy have built in spectrum analyzer, use it.

In a theoretical world the documentation would help. But is your installation ideal?

I would think it would be best not to assume, and do a site survey for each, site, and each cluster. Adjust each one of them for the best performance at that particular time.

I would love to not assume and just test things out, but I have very limited power with our canopy equipment right now. :? The best I can do is just research the potential problems and possibilities, which is why I’ve been spending so much time here.

I would put the two APs that are facing in the same direction on the same frequency, or put the cluster on 3 frequencies at one end of the spectrum and put the single AP on a frequency at the other end of the spectrum

Sync is the magic sauce that makes Canopy work. I would put an SM pointed at the cluster up with the single AP to pass sync from the cluster to the AP (tie RJ11 pins 1, 2, 3, and 6 together). Not having the single AP sync’d with the cluster will definately cause problems.

TFS should not be used unless there is no other way.

Thank you Jerry :smiley:

I guess I shouldn’t be too worried about the distance then (less than 1 mile) just as long as sync and frequency are set up properly?

I’m always worried…

As with anything else test, test, test. Then monitor, monitor, monitor.

Got it :wink:

the problem i had with the keeping the same freq in the same direction was site hoppers. technically it should effect the customers usuage however i get yelled at for the slightest lag on a customers vpn. I found it easier to use the opposite freqs for the same directions then just disable the correct freqs on the SMs.

I havnt run into any problems yet but most of my sites are 3+ miles away from eachother.

Im actually building a site that is 1/4 mile away from another one, maybe i will have to review my freq layouts for that site.

What do you mean by “site hoppers”? Are you talking about SMs re-registering to different APs?

Oh, and by the way, does the Sector ID really control anything? Or is it just for management purposes? I was told during traning to not worry about this parameter, but in my cause with the remote AP is it useful? Ok, never mind…I’m staring right at it in the manual page 240…

Sector ID: Specify a number in the range 1 to 6 to associate with this AP. The Sector ID setting does not affect the operation of the AP. On the AP Eval Data web page of the SM, the Sector ID field identifies the AP that the SM sees.
Well, I hope someone found that useful :roll:

the problem i had with the keeping the same freq in the same direction was site hoppers.

Are you using color codes or am I misunderstanding?

i only have color codes only on a few sites. I tend to get the modem reregistering more even with color codes if they are on the same freq. I tried to set up my network to motos specs but this is what i found worked best for me.

Actually - I had the same problem I was just being hypocritical =P

I don’t use them either I was having huge regfail / rereg problems. I need to update to 7.3.6 though…

ais3101, you may want to look at the packetflux sync pipe for providing sync to a single AP, its a cost effective solution.

Chas / Vince, please explain more the problems you have had with using color codes? We have never thought of not using them!!

I don’t know.

When I used them it seemed like people would re-reg more often. I also noticed that if a signal wasn’t 110% the SM would not register. I would have upwards of 40-50 regfails before they registered. Once they finally registered it would be fine. If they re-reg’d they would rarely regfail.

Kind of odd.

Working pretty well now without them, however.

So is your whole network on one color code?

I had each AP on a different one obviously.

Currently I just leave the frequency open on the SM for the AP that has the strongest signal. It’s annoying because I have to change every SM if I change the AP frequency. However - until I can get things a little less hectic around here - I don’t have a lot of time to mess with it / test it.