Issue DescriptionAfter VIETTEL activated URA_PCH in RNC1, the CS CSSR and PS CSSR decreased as follows.

Checking ResultIf we look into the RRC and RAB separately, we can find that both RRC success rate decreases a little while RAB success rate decreases a lot.

Then we looked into the TOPN sites, and we found that some sites began to have RAB failure due to RL reconfiguration failure before URA_PCH is used. And during the URA_PCH is used, the failure increase while the num of call attempt decrease because URA_PCH can decrease the UE transfer to Idle mode.

We can refer to the following 4 sites.

And the URA_PCH caused more multi-service happen in the network, the signal flow for multi-RAB is more complex than single RAB. For example, when a PS user in URA_PCH received paging for voice call, it needs to finish RB reconfiguration and RB setup to establish the voice call while it need to finish RB setup in idle mode.

If we exclude these 4 worst sites, the CSSR will be more or less the same with before using URA_PCH. So in order to launch new functions in the network, the first task is to deal with the CE shortage in the network. Then the fluctuation on CSSR could be decreased.