8.15 Paging
25.4133GPPRelease 17TSUTRAN Iu interface Radio Access Network Application Part (RANAP) signalling
8.15.1 General
The purpose of the Paging procedure is to enable the CN to request the UTRAN to contact that UE. The procedure uses connectionless signalling.
8.15.2 Successful Operation
Figure 16: Paging procedure. Successful operation.
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
– CSG Id List
The CN Domain Indicator IE shall be used by the RNC to identify from which CN domain the paging request originates.
The Permanent NAS UE Identity IE (i.e. IMSI) shall be used by the UTRAN paging co-ordination function to check if a signalling connection towards the other CN domain already exists for this UE. In that case, the radio interface paging message shall be sent via that connection instead of using the paging broadcast channel.
The Temporary UE Identity IE (e.g. TMSI) is the temporary identity of the user (allocated by that CN Domain) which can be used in a radio interface paging message. If the Temporary UE Identity IE is not included in the PAGING message, the RNC shall use the Permanent NAS UE Identity instead – if no signalling connection exists.
If NNSF is active, and the Temporary UE Identity IE is not included in the PAGING message, the PAGING message shall include the Global CN-ID IE and, in case this PAGING message is originated from the CS domain, the RNC may start the T NNSF timer and store the Permanent NAS UE Identity IE along with the related Global CN-ID IE until the T NNSF timer has expired.
The Paging Area IE shall be used by the RNC to identify the area in which the radio interface paging message shall be broadcast in case no signalling connection, as described above, already exists for the UE. If the Paging Area IE is not included in the PAGING message, the whole RNC area shall be used as Paging Area – if no signalling connection exists for that UE.
The Paging Cause IE shall indicate to the RNC the reason for sending the PAGING message. The paging cause is transferred transparently to the UE.
The Non Searching Indication IE shall, if present, be used by the RNC to decide whether the UTRAN paging co-ordination function needs to be activated or not. In the absence of this IE, UTRAN paging co-ordination shall be performed.
The DRX Cycle Length Coefficient IE may be included in the PAGING message, and if present, the UTRAN shall, when applicable, use it for calculating the paging occasions for the UE.
A list of CSG IDs may be included in the PAGING message. If included, the UTRAN may use the list of CSG IDs to avoid paging the UE at CSG cells whose CSG ID does not appear in the list.
It should be noted that each PAGING message on the Iu interface relates to only one UE and therefore the RNC has to pack the pages into the relevant radio interface paging message.
The core network is responsible for the paging repetition over the Iu interface.
8.15.3 Abnormal Conditions
Not applicable.