Understanding 450m frame utilization?

Ok trying to understand frame utilization vs congestion on a 450m and if i should be waiving the "add a carrier" flag... 

In the below pic 72% utilization, but frame utilization is saying its 99%.

On a 450i i consider this hard line congestion and would have upgraded to a 450m, but with the 450m i don't know which value really means things are becoming an issue, i'm considering an additional carrier and splitting the load.

Based on multiplexer gain and the latest throughput calculator for 450i/m, we should be seeing ~177aggregate at 1.47 but if the frame utilization is to be believed we're topping out at 80mbit ...

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Hello CSup,

You're right, PMP450m is capable of carrying additional downlink traffic when the Frame Utilisation 

reaches 100%. The 100% figure simply means that all of the downlink slots are carrying data - MU-MIMO 

operation permits these slots to carry data to more than one SM at the same time. I tend to think of this 

as stacking more data in each downlink slot. 

I posted some diagrams a while back to illustrate MU-MIMO operation:

    http://community.cambiumnetworks.com/t5/PMP-450/Diagrams-showing-cnMedusa-downlink-MU-MIMO-operation/m-p/80942

For non-MU-MIMO systems Frame Utilisation is a good indication of congestion. However, with 

MU-MIMO the amount of additional data is dependent on a number of factors - including the 

spatial arrangement of the SMs which require data at any particular time. The Statistics -> Frame Utilization 

tab highlights this in the Spatial Utilisation table - you can gauge the congestion particular directions 

from this. MU-MIMO significantly increases the sector capacity but the simple Frame Utilisation 

figure becomes a less useful indicator of congestion.

It may be that the PMP450m is simply meeting the demand.

This post contains more information about the MU-MIMO metrics:

    http://community.cambiumnetworks.com/t5/PMP-450/15-1-1-450m-Additional-MU-MIMO-statistics/m-p/76417

If you are able to capture some field diagnostics (http://AP_IP_ADDRESS/field_diags.cgi) during a busy time

on your sector I would be happy to review them.

Best regards,

simon 

simon.turner@cambiumnetworks.com

8 Likes

A great reply, i sent you a field_diags as well