4.7.9 Paging procedure

24.0083GPPCore network protocolsMobile radio interface Layer 3 specificationRelease 18Stage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.7.9.1 Paging for GPRS services

In A/Gb mode, paging is used by the network to identify the cell the MS has currently selected, or to prompt the mobile to re-attach if necessary as a result of network failure. If the MS is not GPRS attached when it receives a paging for GPRS services, the MS shall ignore the paging.

In Iu mode, paging is used by the network to request the establishment of PS signalling connection or to prompt the mobile to re-attach if necessary as a result of network failure. If the MS is not GPRS attached when it receives a paging for GPRS services, the MS shall ignore the paging.

4.7.9.1.1 Paging for GPRS services using P-TMSI

The network shall initiate the paging procedure for GPRS services using P-TMSI when GMM signalling messages or user data is pending to be sent to the MS while the mobile reachable timer is running. The network may page only GPRS MSs which are GMM-REGISTERED and identified by a local P-TMSI.

In Iu mode, for the MS using eDRX, the network initiates the paging procedure when the paging trigger is received within the paging time window. If the paging trigger is received outside the paging time window, the network initiates the paging procedure at T time ahead of the beginning of the next paging time window.

NOTE: T time is a short time period based on implementation. The operator can take possible imperfections in the synchronization between the CN and the MS into account when choosing T time.

In Iu mode, to initiate the procedure the GMM entity in the network requests the lower layer to start paging (see 3GPP TS 25.331 [23c] and 3GPP TS 25.413 [19c]) and shall start the timer:

– T3315 for this paging procedure, if the network accepted to use eDRX for the MS.

– Otherwise T3313 for this paging procedure.

In Iu mode, if the network starts the timer T3315, the network shall set the timer T3315 to a value smaller than the value of timer T3-RESPONSE (see 3GPP TS 29.274 [16D] for further details on timer T3-RESPONSE).

In Iu mode, the GMM entity in the network may provide the lower layer with a list of CSG IDs, including the CSG IDs of both the expired and the unexpired subscriptions. If there is a PDN connection for emergency bearer services established, the GMM entity in the network shall not provide the list of CSG IDs to the lower layer.

Upon reception of a paging indication, the MS shall stop the timer T3346, if running, and:

– initiate a service request procedure to respond to the paging, the MS shall set the service type to "paging response" in the SERVICE REQUEST message (see 3GPP TS 24.007 [20], 3GPP TS 23.060 [74], 3GPP TS 25.331 [23c] and 3GPP TS 25.413 [19c]); or

– initiate a routing area update procedure as specified in subclauses 4.7.5.1 and 4.7.5.2.1.

If the paging request for GPRS services was received during an ongoing MS initiated GMM specific procedure, then the MS shall progress the GMM specific procedure, and the network shall proceed with the GMM specific procedure.

In A/Gb mode, to initiate the procedure the GMM entity requests the RR sublayer to start paging (see 3GPP TS 44.018 [84], 3GPP TS 44.060 [76]), and shall start the timer:

– T3315 for this paging procedure, if the network accepted to use eDRX for the MS.

– Otherwise T3313 for this paging procedure.

In A/Gb mode, if the network starts the timer T3315, the network shall set the timer T3315 to a value smaller than the value of timer T3-RESPONSE (see 3GPP TS 29.274 [16D] for further details on timer T3-RESPONSE).

In A/Gb mode, upon reception of a paging indication, the MS shall respond to the paging with any LLC frame (see 3GPP TS 44.064 [78a], 3GPP TS 24.007 [20], 3GPP TS 23.060 [74]).

At intersystem change, an MS not having the READY timer running in A/Gb mode or an MS in PMM-IDLE mode in Iu mode, being paged in a different access network as when it last sent user data or signalling message, uses the ROUTING AREA UPDATE REQUEST message as paging response, i.e. the routing area updating procedure shall be performed instead according to the selective routing area updating procedure.

The network shall stop the timer for the paging procedure (i.e. either timer T3313 or timer T3315) when a response is received from the MS.

Upon expiry ofthe timer T3313, the network may re-initiate paging.

Upon expiry of the timer T3315, the network shall abort the paging procedure and shall proceed as specified in 3GPP TS 23.060 [74].

In Iu mode, when a response is received from the MS, the network shall change from PMM-IDLE mode to PMM-CONNECTED mode.

In A/Gb mode, when a response different from an LLC NULL frame is received from the MS, the network shall start the READY timer.

4.7.9.1.2 Paging for GPRS services using IMSI

Paging for GPRS services using IMSI is an abnormal procedure used for error recovery in the network.

The network may initiate paging using IMSI if the P-TMSI is not available due to a network failure.

In Iu mode, to initiate the procedure the GMM entity in the network requests the lower layer to start paging (see 3GPP TS 25.331 [23c] and 3GPP TS 25.413 [19c]).

In A/Gb mode, to initiate the procedure the GMM entity in the network requests the RR sublayer to start paging (see 3GPP TS 44.018 [84], 3GPP TS 44.060 [76]).

Upon reception of a paging indication for GPRS services using IMSI, the MS shall stop the timer T3346, if it is running, locally deactivate any active PDP context(s), MBMS context(s) and locally detach from GPRS. The local detach includes deleting any RAI, P-TMSI, P-TMSI signature and GPRS ciphering key sequence number stored, setting the GPRS update status to GU2 NOT UPDATED and changing state to GMM-DEREGISTERED. The MS shall stop all timers T3396 that are running.

If S1 mode is supported by the MS, the MS shall in addition handle the EMM parameters EMM state, EPS update status, last visited registered TAI, TAI list, GUTI and KSI_ASME as specified in 3GPP TS 24.301 [120] for the case when a paging for EPS services using IMSI is received.

In Iu mode, when an MS receives a paging request for GPRS services using the IMSI from the network before an MS initiated GMM specific procedure has been completed, then the MS shall abort the GMM specific procedure, and the MS shall proceed according to the description in this clause.

After performing the local detach, the MS shall then perform a GPRS attach or combined GPRS attach procedure.

After performing the attach, the MS should activate PDP context(s) to replace any previously active PDP context(s). The MS should also perform the procedures needed in order to activate any previously active multicast service(s).

NOTE 1: In some cases, user interaction may be required and then the MS cannot activate the PDP and MBMS context(s) automatically.

NOTE 2: The MS does not respond to the paging except with the Attach Request. Hence timers T3313 and T3315 in the network are not used when paging with IMSI.

NOTE 3: Paging without DRX parameters may require a considerable extension of the paging duration.

NOTE 4: Paging without using eDRX parameters may result in the paging with IMSI not to be received by the MS for which eDRX has been negotiated or may require a considerable extension of the paging duration.

4.7.9.2 Paging for non-GPRS services

The network may initiate the paging procedure for non-GPRS services when the MS is IMSI attached for non-GPRS services.

In Iu mode, to initiate the procedure the GMM entity requests the lower layer to start paging (see 3GPP TS 25.331 [23c] and 3GPP TS 25.413 [19c]) for non-GPRS services.

In A/Gb mode, to initiate the procedure the GMM entity requests the RR sublayer to start paging (see 3GPP TS 44.018 [84] and 3GPP TS 44.060 [76] for non-GPRS services).

The MS identity used for paging shall be the allocated TMSI if acknowledged by the MS, otherwise the IMSI.