This article is about RRC counters used to find RRC failures (LTE), Failure Causes and Solution. After, we discussed one by one RF optimization possible solutions of RRC Setup Failure Measurement and what actions can be taken by RF 4G optimization engineer.
RRC counters, failure causes and solution in LTE
| Counter Name | Failure Cause | Solution |
| L.RRC.SetupFail.ResFail | Resource allocation failures. | Check RRC Connected user and remaining Resource (PUCCH,SRS and PRB Utilization). Increase connected user license or configure parameter mentioned below. |
| L.RRC.SetupFail.ResFail.SRS | SRS resource allocation failures. | The SrsSubframeRecfSwitch option of SrsAlgoSwitch |
| L.RRC.SetupFail.ResFail.PUCCH | PUCCH resource allocation failures. | The SriPeriodAdaptive option of PUCCHcfg be selected |
| L.RRC.SetupFail.ResFail.UserSpec | limitation of UE number specification. | Check Active UE utilization / Load balancing (Intra-Inter)/ upgrade board (UBBPe6/9) which support more UE. Check UE Specific issue |
| L.RRC.SetupFail.ResFail.Other | Other resource allocation failures. | |
| L.RRC.SetupFail.ResFail.CellBarred | cell is barred. | Disable Cell Barred if configuration mismatch / Disable Service completely / redirect service to low loaded or legacy network. |
| L.RRC.SetupFail.NoReply | No responses from the UE. | Poor RF Coverage and UL RSSI/ Adjust QRxLevMin /SmartPreAllocationSwitch /SrbProbeSchSwitch |
| L.RRC.SetupFail.Rej | RRC Connection Reject messages sent to UEs in a cell. | Main counter for all the cause |
| L.RRC.SetupFail.Rej.MMEOverload | MME overload. | Raise with Core |
| L.RRC.SetupFail.Rej.Other | Other causes. | |
| L.RRC.SetupFail.Rej.ForbidAc | UE access beyond the cell radius. | Check TA and Restrick coverage within cell range by adjusting power or Tilt |
| L.RRC.SetupFail.Rej.MMEOverload.RxOverloadInd | eNodeB receives MME overload indications. | Raise with Core |
| L.RRC.ConnReq.Msg.disc.FlowCtrl | RRC Connection Request message is discarded due to flow control. | Timer 300 and Timer 302 |
| L.RRC.SetupFail.Rej.FlowCtrl | The eNodeB sends an RRC Connection Reject message to the UE due to flow control. | |
| L.RRC.ConnReq.Msg.disc.Illegal | RRC Connection Request messages are discarded because the messages are illegal. | UE Issue / High UL RSSI / Timer 302 |