Interference with other wireless systems

Has any other Canopy operators out there experienced interference issues with other local wireless operators using gear other than Canopy?

Back in August we signed on a customer and noticed that the RSSI and Jitter readouts on the Status page of the SM were not corresponding to the excellent tone that we were receiveing on the headset. Although a speed test after installation was 1.5Mbps to the Internet, ping times from our core router to the customer could get as high as 1400ms during certain periods of the day. At first we suspected that it was the Canopy Surge Suppressor, and removing the ground actually did help, but the ping times were still bad.

We changed the frequency of the AP that the customer was connected to and the RSSI sky-rocketed and ping times were down to the normal 20ms. We concluded that it was an interference issue, which was a possibilty from the beginning due to a neighboring business having some type of flat panel pointed at a tower on the mountain that we know a competitor leases space on. We also know that they are not using Canopy, therefore no CMM for timing.

Since we changed the frequency, everything was fine-and-dandy until today when I did my daily check of the network. Ping times are back in the 1400ms range. I suspect that either the customer was experimenting with the ground (they really want the device to be grounded) or the neighboring business CPE had its frequency changed and/or the transmitting AP frequency was changed and the interference is back.

Just wondering if anyone else in the business has experienced problems with other wireless providers not using Canopy.

Yes, interference can use problems like this, but sadly, it’s very tricky to detect interference on canopy systems…

You probably already did this, but did you do a good spectrum analysis of the area? You didn’t mention what freq you’re using, but the newer boot version of 5.7/5.2 has a spectrum analyzer built in, I believe.

Yes, the firmware of the SM’s have spectrum analyzers in them, but in all honesty their readouts are terrible and inaccurate. We bought a REAL spectrum analyzer and a 5.7 directional antenna and dish. We purcahsed it after we solved the first problem by changing the frequency.

We have six 5.7 Access Points, that WERE using three frequnecies:

AP 1&4 - 5745 MHz
AP 2&5 - 5765 MHz
AP 3&6 - 5785 MHz

Backhauls - 5800 MHz

The interference was on AP #3 at 5785 MHz. We enabled the ISM band frequencies on the AP and SM and chose the highest frequency available, 5840 MHz. That solved the problem for the time-being. I am going to try to find a clean frequency on Friday and possibly take the spectrum analyzer out to see what I can find.

This may be nothing, but I thought we needed 25Mhz separation on each AP. I noticed you originally used 20Mhz.

P.S… it is 20Mhz. You were correct.

Well, BHs needs 35-40mhz separation if they are nearby. I had setup a link
for the same pole, 30deg defference, about 10miles. With 30mhz separation linktest showed 85%, with 40mhz, 100%. Keep in mind!

Well, I think I may have jumped to conclusions when I said that it was an interference issue. After we switched the frequency the first time and solved that problem (and yes, that defnitely was the problem the first time around), we ran into an issue where the SM would register, re-register, and then eventually died for about 1 week. We went to investigate and found that there was construction being done on the roof, and an air conditioner was serviced since we were last there. Whoever serviced the AC left the door to the unit open, and it kept getting caught in the wind and knocked our SM out of alignment. Needless-to-say, we went back, repointed, and moved the dish to the side of the AC that was not reachable by any of the doors.

About 1 week after that is when we started experiencing the issues that I claimed was due to interference. Once I was back in the area, I did some tests and I was able to force other SM’s in the network to connect to the AP that I thought was experiencing the interference. (After the first issue, SM’s that were < 1 mile away from the tower could not connect to the AP with the intereference issue). So, this ruled out the intereference being at the AP level.

I spoke to some people and found out that the roof-crew at this location had since been back, and the dish could have possibly been knocked out of alignment again, but not by a door. I have yet to go back to see what the issue is.

AP’s should have 20 MHz of seperation, however Motorola recommends 25 MHz, so we were both right.

Interesting fact about the backhaul. It is a good thing to know, since we are about to start the implementation of a 3-link backhaul system on a neighboring tower for a hospital. Two of the links will be on the north side of the tower, and the third will be on the south. We were thinking of reusing one of the frequencies from the back for the front link since they are in opposite directions, and of course a CMM will be used. This way we don’t tie up more of the spectrum than necessary.

Any suggestions?