Overlapping RF


Was wanting to get details on overlapping 900Mhz frequencies please.

I have read on the forums that there is an issue but couldn’t find details.

I know this much, 906, 915, and 924 don’t overlap with others in the same band or each other I think.

We have 8 sites with 2 of those site have 3 AP’s with overlapping frequencies. 1 site is using 906,913, and 920. The other site has 906,907, and 915.

I think there maybe another issue with some of our sites overlapping over range. For instance, we have a site that is broadcasting 919 (360 degree) with a range of 7 miles and another AP at 916 that has a range of 4 miles (60 degree) and thay are within a few miles apart. Another overlapping situation example we have is a 915 AP at 6 miles and a 916 AP at 7 miles, and they are both 360 degree and they are only 5 miles apart.

I am new to the company I work for and they have put me in charge of there wireless troubleshooting and there network for wireless was setup a few years ago and I don’t think it was setup that well and there is alot of changes that need to be made b/c of problems and I am wondering if this os one of them…

Thanks in advance.

Welcome to the forum.

Start with reading the manual. much of what you need to know is in there.

A few things to search and read on this forum.

GPS timing
Balancing RF Levels
Self Interference

To get you going in the right direction:
Every 900MHz radio in your network needs to have GPS timing (sync). CMM, CMMmicro, SyncPipe, Last Mile CTM, etc. sync is the magic sauce that make Canopy work.

There are 3 non overlapping channels 906, 915, 924. Using any other combination will result in self interference.

Every 900MHz AP that can hear another 900MHz AP needs to be configured with the same # Control Slots, Max Distance, and Downlink %. Alternately you can use the Frame Calculator Tool to determine alternate configurations (see manual) but it gets messy.

The RF spectrum is the medium in which 90% of your problems will occur. If I were walking into a new network, the first thing I would do is look at ALL of the RF spectrum. The quickest and easiest way to get a feel for what the spectrum looks like (to your Canopy AP’s) is to turn off every AP and put each one in SM mode. Take a screen shot of the spectrum analyzer screen. Use a spreadsheet to document the levels at each frequency on every AP. Then work out channel assignments for AP’s taking the sources of interference into account.

Once you re-channelize your network, you may have some customers that can’t connect. You may need to roll a truck to install a higher gain antenna, however once you get everything configured right and all customers reconnected you will find your network will run the way it’s supposed to.

NOTE: Follow the manual design guides as closely as possible. Every variation is a compromise to the network performance as a whole.

Good luck.

Thanks for the reply Jerry you’re very helpful.

As far as turning off all our AP’s switching to SM and looking at the frequencies is hard to do. For one, we knock all our customers off the Internet, and people from these parts don’t know a good thing even when it’s handed to them.

I will run this by the higher ups; I was thinking this is what needs to be done, but not sure how they will handle it.

I was able to talk them into letting me go from site to site from what I learned from you last time. I have been checking the noise floor of our current frequencies and then adjusting customers the best I can. There are still a lot of VERY hot connections close to our AP’s though. I’ve done 4 out of 8 of our AP’s so far.

But the more I look at it, the more I’m seeing there are a lot of frequency issues here. And from my test I am seeing that we are using the wrong frequencies in some places. Either way, thanks for your help again.

p.s. Sorry I don’t have the time I would liek to read the manual. I have read a few pages, but for the most part the customers (wireless) keep me busy.


RTC Communications

that’s why you do it during a maint window…

there is no way to get an accurate baseline unless all APs are off. not doing it wil prolong your problems indefinately.

for every 5 minutes you don’t spend reading the manual add 1 hour of pain to your troubleshooting efforts…

canopy is easy to learn, hard to master.