I have discovered an issue at a site where I’ve got about 100 customers coming in. It was configured with one Pacific Wireless 13dBi omni on one tower, and three Teletronics 22dBi sectors on another tower of about 1-2 meters lower height, about 20 meters to the west of the tower with the Omni.
Tower 1 - 40 ft Rohn 25G, 5GHz point to Point antennas, 13dBi 2.4GHz h-pol omni. Operating in 20MHz channel, 802.11-B-Only mode.
Tower 2 - 50ft tower. Unknown make. Has significant AT&T Cellular antennas. Our antennas are the very topmost on the tower, and are 22dBi teletronics 140 degree h-pol sector antennas. They are about 8-10ft above the AT&T antenans at the next level down. Operating in 10MHz channel, 802.11G-Only mode, NStreme enabled. Since the photo was taken, this was changed out to an 13dBi h-pol omni. No observable changes were made to performance, but signal strengths are stronger! You would think they would be lower going from 22dBi to 13dBi, but they in fact went up!
From both of these towers when I run a scan I’m showing noise floors fluctuating wildly, from -98dBm to -81dBm! I am seeing these fluctuations on both towers, but the tower2 is seeing -81dBm worst case where tower1 is seeing -87dBm worst case when I run the scans individually. When I run them at the same time, the fluctuations are still there; so I don’t think the towers are interfering with each other. The 20MHz interface operates on center 2422MHz, the 10MHz interface operates on center 2462MHz, so they should be far enough apart for that to not be an issue.
I’m not sure how long this has been going on. I have never been impressed with the performance of those sector antennas, which were put up after the cellco stuff was already in place. I am wondering if it may have simply always been a problem - if customer signal was lower than about -80dBm, service never worked very well on that unit. I replaced the three sector antennas with another ODH24-13 h-pol omni, per my notes above.
One of the AT&T cell phone antennas right at the base of my mast on tower 2 is lose and flopping. Perhaps the antenna is damaged? Could this cause 2.4GHz interference if it’s one of their 1.9GHz radios on that antenna? I contacted AT&T and reported the damaged antenna, but they didn’t give me a ticket number, weren’t willing to take my number for a callback, and basically gave no indication that they would do anything about it at all.
I would appreciate any feedback and/or suggestions regarding this issue.
