How to solve ERAB Failure due to "No Radio Resources" (L.E-RAB.FailEst.NoRadioRes)?

Hello Experts,

Can anyone help to solve high ERAB failures due to L.E-RAB.FailEst.NoRadioRes on Huawei LTE?

No radio resources for VoIP means there is too much traffic.
You need to reduce traffic by sector split, load balancing, etc.

It is generally caused by license of RRC Connected Users.
But can also be due to Transmission Capacity issues.

The issue it suddenly increased in network.
No traffic patteren looks like increased.
Is there any correlation?

If your plot the graphs of erabs established and this counter you will see a correlation.

What are affected KPI?
Only accessibility?

Yes, for now only accessibility.
But later it may affect RRC too as traffic increases.
It may affect Retainability as cell may not accept Handovers for VoIP eRABs.

Only load balancing is the solution, or is there any parameter we can play?

Share some traffic with surrounding cells and you will get rid of the problem.
Note: Look also at your VoLTE KPIs.

Check if service type is “voip” or not for qci 1 & 5.

There are features too for VoIP no resource.
If bandwidth is low then its better to shift traffic in idle or connected mode.
Check l.traffic.user.avg.voip and cce and prb and voip prb utilization.

At least Uplink compensation scheduling should be enabled.
And check VoIP quality.
ROHC feature.

You better dig further and identify which cells have this issue.
Maybe codec negotiation for VoLTE was changed in IMS and now you have this problem.
Or possibly something else.
Check to see with what other counters is correlated.

RLC amrc mode basically should be amr and evs mode for quality and capacity purpose VoLTE rate control feature.

If traffic voip.user has increased suddenly check optlog of that time if any changes done.

Yes got the clue: actually 8 cells were impacted.
One site running with no license causing the scenario.

Then it is easy.
There should be license alarms for all such sites.