09 WCDMA RNO Access Failure Problem Analysis WCDMA Access Problems Analysis ReviewReview Access is associated with the call setup success rate of the network This KPI can be optimized by means of “Cal[.]
WCDMA Access Problems Analysis Review Access is associated with the call setup success rate of the network This KPI can be optimized by means of “Call setup test” and the consequent trouble-shooting based on access failure analysis Objectives When finished this course,you will be able to: Be familiar with the access procedure in UMTS Do analysis on access problems independently Course Contents Definition of access failure Access problem analysis process Common reasons for access problems Case study Definition of access failure General originating call setup signaling flow: Definition of access failure General terminating call setup signaling flow: Definition of access failure Call setup succeeds when the call setup phase is completed (when CC Connect is received) If the call fails to reach the CC Connect stage, it should be pegged as an access failure Course Contents Definition of access failure Access problem analysis process Common reasons for access problems Case study Access problem analysis process Preparation before Analysis Access problem analysis methods Preparation before analysis Be familiar with the planning information which can be obtained from planning reports; Be familiar with history records of optimization; Get the latest reliable summary sheet of the engineering parameters; Get the latest configuration of radio parameters; Obtain the network traffic statistics and the subscriber complaint information of access Access failure during handover process And the downlink Bler reaches 100%: Access failure during handover process UE report the measurement of cell Sc508 which request the active set update: Access failure during handover process The report was received properly and “RRC_ACTIVE_UPDATE” was sent as response while UE didn’t received it which results in the access failure: Access failure during handover process Let’s turn to the performance of the terminating UE During the access process, the measurements from the terminating UE were not satisfactory either: Access failure during handover process Access failure during handover process While the radio links hold on till successful handover is completed: Access failure during handover process Then the originating UE loses connection to the network and access released where the cause is “destination out of order” from the signal traced by the terminating UE: Case study Access failure due to synchroni-za tion failure Access failure during RB setup Access failure during handover pr ocess Access failure due to terminating UE Access failure due to terminating UE Access failure location (UE Ec/I0 ): Access failure due to terminating UE The coverage is not bad where the UE originates the VP access: Access failure due to terminating UE CN send “disconnect” message with the cause “bearer capability not authorized” before access failure: Access failure due to terminating UE setup signaling procedure for RRC and RAB have already finished The cause of disconnect is the same: Access failure due to terminating UE The reason is: we use two mobile to test video phone, for the originating call mobile camped in 3G network, but the terminating call mobile camped in 2G network that moment, so video call setup failed, the missing signaling of terminating UE can also explain it: Summary Access process is complicated since different devices are involved and scenario varies Careful study from signal distribution to signaling procedure makes things easy Examples above are derived from tests carried out before, which give general idea of trouble shooting, advanced researches will be supplemented