Paging in packet PS

The CN initiates the procedure by sending a PAGING message. The PAGING message
shall contain the following IEs:
-  CN Domain Indicator
-  Permanent NAS UE Identity

-  DRX Cycle Length
Coefficient (if available)

The PAGING message may contain following IEs:

-  Temporary UE Identity
-  Paging Area
-  Paging Cause
-  Non Searching Indication
  Global CN-ID