LTE: How does network initiate bearer creation for an UE ?

Question

I have a query related to Dedicated Bearer Creation.

If two UEs are attached to the network and if network is triggering the Dedicated Bearer Creation, how network identifies for which UE it has to create the Dedicated Bearer. Because as part of Create Bearer Request that is from PGW-SGW-MME we are no where specifying the IMSI value or something else related to UE. So how will network identify the UE and initiate the Bearer Creation.?

Answer 1

When you tries to activate any service in which network has to play its part for e.g. IMS voice call or VoLTE in that case when user will make a request P-CSCF will trigger an AAR message to PCRF with the requested bandwidth and the filters to be applied.
PCRF will then bind those filters in Charing-Rule-Install and grant some qos to those filters using some policy definition filters.
PCRF will send that rule in RAR message to PGW which in-turn will trigger a Create Bearer Request to SGW and SGW will forward it to MME. MME sends Create Bearer Response with EPS-Bearer-Id to SGW and then it reaches PGW and hence a dedicated bearer for that service is created

Regards,
Peeyush Sharma