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http://taktiktek.blogspot.in/2011/11/rrc-access-failures.html RRC ACC FAIL DUE TO RADIO INT SYNCH NetAct name: RRC_CONN_ACC_FAIL_RADIO Description: The number of RRC access failures caused by radio interface synchronisation failure When the RNC does not receive the RRC: RRC CONNECTION SETUP COMPLETE message from the UE within 6 seconds, and the RNC has not received the NBAP message which indicates that L1 synchronisation has been established between UE and BTS. This counter is updated also in case of inter-system handovers and inter-RNC hard handovers

RRC ACC FAIL DUE TO UU INT NetAct name: RRC_CONN_ACC_FAIL_MS Description: The number of RRC access failures caused by UE. When the RNC does not receive the RRC: RRC CONNECTION SETUP COMPLETE message from the UE within 6 seconds, and the RNC has received the NBAP message which indicates that L1 synchronisation has been established between UE and BTS. This counter is updated also in case of incoming SRNS relocations, inter-system handovers, and inter-RNC hard handovers

RRC ACC FAIL DUE TO RNC INTER REASONS NetAct name: RRC_CONN_ACC_FAIL_RNC Description: The number of RRC access failures caused by RNC internal reason. When an RNC internal failure occurs before receiving the RRC: RRC CONNECTION SETUP COMPLETE message from the UE. This counter is updated also in case of incoming SRNS relocations, inter-system handovers, and inter-RNC hard handovers

3G - Optimization - Failure analysis Failure analysis : 

1. RRC Setup Failures, Evaluate RRC Setup Failure at cell level

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Evaluate the distribution among failure reason

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In case the dominant factor is: RRC_CONN_STP_FAIL_RNC --> at the moment no optimisation action is needed (typically is a fault or Incoming SRNC Relocation failures) RRC_CONN_STP_FAIL_ AC --> look at UL interference & DL power (-> UL power spikes & need to upgrade radio capacity Solution : Disable UL Admission Control if the number of failures is critical

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RRC_CONN_STP_FAIL_ BTS evaluate NBAP counters (radio link reconf. failure) and KPIs for troubleshooting BTS resource use Pool Capacity KPI in order to evaluate lack of channel elements

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check BTS configuration in terms of WAM and WSP allocation

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expand the capacity or decrease the traffic offered to the site

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in case the BTS is not responding delete and re-create the COCO

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RRC_CONN_STP_FAIL_ TRANS evaluate the number of reconfiguration failure due to transmission

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Check COCO configuration

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Use AAL2 Mux in case of two WAM

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expand the capacity or decrease the traffic offered to the site

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2. RRC Access Failures Evaluate RRC Access Failure at cell level

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Evaluate the distribution among failure reasons

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In case the dominant factor is:

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RRC_CONN_ACC_FAIL_RADIO --> it should be detected through drive test if UL or DL coverage: UL Coverage --> tune CPICH and cell dominance (if UL interference is not the cause)

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DL Coverage:

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If UE does not receive the RRC Setup message --> tune SCCPCH Power

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If UE does not synchronised in DL --> reduce N312 from 4 to 1 (tuning depends on UE model) or tune CPICHToRefRABOffset vs Qqualmin (or Qrxlevmin) RRC_CONN_ACC_FAIL_ MS --> UL Coverage