We are deploying a new network of 450m and 450i APs in a mountain area with lots of pine trees. All SMs so far are less than 1 mile from the AP. Some SMs are showing dramatically fluctuating modulation rates. All SM RSSI levels are between -45 and -65 and there doesn’t seem to be a correlation between RSSI and modulation. Some SMs with -62 RSSI stay at 8X while some at -45 are mostly at 4x but fluctuate from 2-8x. This is happening on both 450m and 450i APs. Most are on 16.2.3.1. Moving some to 20.0.1 did not make any difference. Spectrum analysis is extremely clean.
I’m wondering if it is multi-path through the trees or maybe the edge of the sector? With the mountains, we have some above or below the vertical beam.
SM target receive level is -52. We originally thought the issue was wind/snow on the trees, but some SMs are still experiencing the issue with no snow and calm. So probably multiple issues. Definitely a couple of the worst SMs are on the edge of the antenna pattern. One thing we noticed is there is some correlation with RSSI imbalance and MCS fluctuations. We are going to down tilt a couple APs even more than -8 they are. Not used to shooting short range down into a valley.
One interesting note, we see RSSI increase 6-12 dB at night for a number of SMs. Not sure if that is really happening or a reporting/graphing issue.
I had some nasty issues with -52dB TRL on 16.2.3 (i’m assuming 16.2.3.1 is same). Support told me as of that release to raise TRL to at least -58dB. Worth a shot I figure.
Are you saying you’re seeing large SSR on some these?
The weather this past weekend was pretty nasty with the wind!
+1 on wind. When its windy we see similar modulation swings on the 450i 900. Snow also causes some fading issues but gusty winds can result in some pretty wild modulation swings for us, but it usually has to be very gusty, i.e. 30 mph and up. Depending on the wind direction, we have actually seen some SM’s improve during high wind events. There’s science in there somewhere.
try to align first the APs very slowing while observing the clients signal to see if it can improve on the tilt and azimuth.
As you have better RSSI on clients in the night, I would ask you if you have other operators in your area using 3.5 GHz band as wherever I have seen better service on SMs in the night is in place where during the day, there is interference from other operators and as in the night devices are not much in operations, the service is better.
Pine needles are about half the wave length of your frequency, think of your path as having fractal mirrors. There will be a large amount of multi-path going on.
My suggestion is to move to 2.4GHz or even better 900MHz. 3.5GHz is good for leafy foilage but my experience has been to avoid the higher frequencies with anything that has fir or balsams (pine is part of the balsam family) in the path.
