B5c MIMO information missing for one chain


#1

I have a 15Km link with Mimosa B5c. We had interference problems in the band it was running into and I noticed that there is an end of the link that does not seem to deliver MIMO status information. We changed the mode and it is now working in 2x20 but we still do not get data from the remote end. Is this an indication that the remote device is not Tx on one of the chains? May be I am interpreting this in a wrong way…

Note: The remote end has not been hardware rebooted. We performed only a remote reboot but no change in the symptom.


#2

Hi Cesar,

The image on the left is the RF Chains (physical or PHY layer), while the image on the right is the Streams (MAC layer). Missing Rx power (on the left) is the cause of the missing streams (on the right). These both indicate that the radio is sending and receiving on the vertical polarization only.

Most often, we see both chains of the same polarization fail due to cabling problems such as tight bends or water ingress. The problem could also be an obstruction in the horizontal polarization, or a radio transmit or receiver problem (Tx or Rx).

To determine the cause, swap both ends of the RF cables between horizontal and vertical polarization. If the problem follows the cable, replace the cable. You may also need to perform this step on the opposite side of the link.

A more complete troubleshooting guide can be found here:
http://backhaul.help.mimosa.co/backhaul-troubleshooting-guide-tx-rx-low-power

I don’t think the following is the problem, but another reason for dropped chains with a single channel on one end of a link is the dual-link feature. People sometimes confuse missing chains for a hardware problem, when the radio is dropping chains with heavy interference intentionally: http://backhaul.help.mimosa.co/backhaul-faq-dual-link


#3

I also miss on both V and H. It’s issue by hardware device?


#4

Hi Chung,

It could be any of the problems mentioned above. Please first follow the troubleshooting guide, and then contact Support if you still have a problem.