RRC Failure reasons

4G LTE
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1

Hi Experts,
What could be the reason of RRC connection failure and RRC reestablishment failure?

Experts please have glimpse over that

Thanks

2

RRC connection failure cause: radio resource congetion (PUCCH, SRS, user number), poor radio link
RRC reestablishment failure cause: no UE context

3

What could be issue in RRC reestablishment reject or failure in LTE?

4
  • Reject: UE context not available
  • Failure: many reasons like poor RF, etc.
5

Missing neighbour relation.

6

Yes because of that UE context exchange will not happen.

Reject-CAC failures also. (call admission control)

7

Huawei FD, it has flow of CAC.
LTE check such as pucch, srs… one by one.

8

Inter-Modulation Interference and channel unbalance leading RRC failure due no reply

Number of RRC Connection Reject messages sent to the UE in a cell ( enodeB Faulty alarm ,CPU load , number of users exceed )

9

Hi @sadanandk2, I just want to know in what cases UE context not available to enodeb or MME

10

In case of missing neighbour the new eNodeB (where UE does re-establishment) cannot retrieve UE context from old enodeB due to missing X2.
So dropped is pegged as an MME drop but in reality is an RF/RAN drop.

1 Like
11

It can be case of HO ok, but in normal case where RRC reestablishment reject, in that case what would be reasoN for UE context not available?

12

Missing X2 between those 2 eNodeBs.
Or congestion could be cause of rejection.
Congestion due to lack of resoruces like SRS, PUCCH, etc.