Owj104103 Wcdma Access Analysis Issue1.0

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Owj104103 Wcdma Access Analysis Issue1.0

Transcript of Owj104103 Wcdma Access Analysis Issue1.0

training slideOverview
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.

Do analysis on access problems independently
When finished this course,you will be able to:

Case study




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 .


Case study

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.



Traffic statistics data analysis
Coverage analysis
Signaling analysis


Access problem analysis methods
Traffic statistics data and custom complaint collection reveal problems exactly, further trouble-shooting can be carried out by call setup test. While for a pre-commercial or trial network, call setup test is the effective way.


Case study
RF reasons



RF reasons

Improper settings of access threshold
Inappropriate settings of preamble power ramp step and retransmission times
Inappropriate setting of adjacent cells
Inappropriate setting of synchronization parameters
Unsuitable power allocation rate for common channel
Unsuitable initial power of uplink and downlink dedicated channel
Unsuitable setting of uplink Initial SIR target value of dedicated channel


RF reasons



Case study
Access failure during RB setup
Access failure during handover process
Access failure due to terminating UE


Access failure location:
Access failure due to synchronization failure
UE Txpower reaches maximum value 21 dBm during VP call setup. So this call setup failure may be caused by Uplink synchronization failure:


Access failure due to synchronization failure
UE does not send RRC Connection Setup Complete to RNC after receiving RRC Connection Setup message from RNC :


Access failure during RB setup
Access failure during handover process
Access failure due to terminating UE


Access failure location:
Access failure during RB setup
UE Tx power is very low and downlink pilot Ec is high before access failure,but Ec/Io is not very good :


Access failure during RB setup
The cause of call setup failure is Requested circuit/channel not available:


Access failure during RB setup
RNC didn’t receive RB Setup Complete message after it has sent RB Setup message to UE. Timeout of RNC is reached after 1.5s:


Access failure during RB setup
Access failure during handover process
Access failure due to terminating UE




ScannerEc/I0 :
Scanner BestServer :


During access process, UE Txpower is rising rapidly :


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
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:


Access failure during RB setup
Access failure during handover process
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. .