PMP450i and MIMO

Hi !

Wireless network infrastructure consist of four sectors based on Cambium AP 450i.
Each sector has one Access Point.
Uplink and Downlink rates of sector 2, 3, 4 are MIMO-B.
Sector 1 has Uplink rate MIMO-B and Downlink rate MIMO-A.
The situation is as follows. If any Subscribe Module from sector 1 connects to sector 2, the Uplink and Downlink rates become MIMO-B. And if any Subscribe Module from sector 2 connects to sector 1, the Uplink rate becomes MIMO-B and Downlink rate becomes MIMO-A.
I wonder what could be the cause of such a behaviour?

sector 1 and sector 4 status

Sector 1 Sess Status Device

Sector 4 Sess Status Device

You don’t have the rate adapt algorithm set to Mimo-A only do you? The signals are generally very poor, so even a bit of noise might also cause this.

Hi Jacob! Thanx for the replay. We do have the rate adapt algorithm set to MIMO-A/B. All the settings are the same for all the sectors. APs have the latest firmware updates. But only sector 1 has such a behaviour. And we don’t understand why it is happening. Maybe there is a way to diagnose the problem? Maybe some kind of tests?

Is there interference on that AP? Do the logs show anything? Could be a bad AP.

The logs show nothing suspicious. The AP could be bad but for now we don’t have an opportunity to replace it. We try to check everything that possible, so any ideas are welcome.

I would open a ticket with cambium and give them the engineering files. They might be able to detect something.

What is your frequency plan? (Frequencies and channel bandwidths)

If you run Sector Spectrum Analyzer from all the APs on the sector at the same time (automatically runs on the connected SMs), do you see any energy on your channel at the SMs?