KNOTS AND PROCEDURES FOR RADIO CALL HANDLING

Description

TECHNICAL FIELD

[0001] Embodiments herein relate generally to a Control plane (CP) node, a method performed by the CP node, a Radio Access Network (RAN) node and a method performed by the RAN node. More particularly the embodiments herein relate to handling paging.BACKGROUND

[0002] According to the current 3GPP TS 23.501 V1.4.0 (2017-09), the 5G System architecture is defined to support data connectivity and services enabling deployments to use techniques such as e.g. Network Function Virtualization (NFV) and Software Defined Networking (SDN). The 5G System architecture shall leverage service-based interactions between Control Plane (CP) Network Functions where identified. One key feature of 5G is to separate the User Plane (UP) functions from the Control Plane (CP) functions, allowing independent scalability, evolution and flexible deployments e.g. centralized location or distributed (remote) location.

[0003] Figure 1 and figure 2 illustrate the architecture for a 5G system according to an example of the present disclosure. The 5G architecture is service-based and comprises network functions which interact with each other. Figure 1 illustrates a non-roaming 5G System Architecture according to an example of the present disclosure and figure 2 illustrates a Roaming 5G System architecture-Home routed scenario according to an example of the present disclosure. The interfaces or reference points between the network functions in figures 1 and 2 may be referred to as service-based interfaces.

[0004] The example architectures in figures 1 and 2 comprise at least some of the following entities: Authentication Server Function (AUSF) Access and Mobility Management Function (AMF) Data Network (DN), e.g. operator services, Internet access or 3rd party services Unstructured Data Storage Function (UDSF) Network Exposure Function (NEF) NF Repository Function (NRF) Network Slice Selection Function (NSSF) Policy Control function (PCF) Session Management Function (SMF) Unified Data Management (UDM) Unified Data Repository (UDR) User plane Function (UPF) Application Function (AF) User Equipment (UE) (Radio) Access Network ((R)AN) 5G-Equipment Identity Register (5G-EIR)

[0005] The example 5G system architectures in figures 1 and 2 comprise at least one of the following service-based interfaces: Namf: Service-based interface exhibited by AMF. Nsmf: Service-based interface exhibited by SMF. Nnef: Service-based interface exhibited by NEF. Npcf: Service-based interface exhibited by PCF. Nudm: Service-based interface exhibited by UDM. Naf: Service-based interface exhibited by AF. Nnrf: Service-based interface exhibited by NRF. Nnssf: Service-based interface exhibited by NSSF. Nausf: Service-based interface exhibited by AUSF. Nudr: Service-based interface exhibited by UDR. Nudsf: Service-based interface exhibited by UDSF. N5g-eir: Service-based interface exhibited by 5G-EIR.

[0006] The example 5G system architectures in figures 1 and 2 comprise at least one of the following reference points: N1: Reference point between the UE and the AMF. N2: Reference point between the (R)AN and the AMF. N3: Reference point between the (R)AN and the UPF. N4: Reference point between the SMF and the UPF. N6: Reference point between the UPF and a Data Network. N9: Reference point between two UPFs. N5: Reference point between the PCF and an AF. N7: Reference point between the SMF and the PCF. N24: Reference point between the PCF in the visited network and the PCF in the home network. N8: Reference point between the UDM and the AMF. N10: Reference point between the UDM and the SMF. N11: Reference point between the AMF and the SMF. N12: Reference point between AMF and AUSF. N13: Reference point between the UDM and Authentication Server function the AUSF. N14: Reference point between two AMFs. N15: Reference point between the PCF and the AMF in case of non-roaming scenario, PCF in the visited network and AMF in case of roaming scenario. N16: Reference point between two SMFs, (in roaming case between SMF in the visited network and the SMF in the home network). N17: Reference point between AMF and 5G-EIR. N18: Reference point between any NF and UDSF. N22: Reference point between AMF and NSSF. N27: Reference point between NRF in the visited network and the NRF in the home network.

[0007] The current 3GPP TS 23.501 V1.4.0 (2017-09) has introduced the Radio Resource Control (RRC) inactive state. 5GC shall provide the RAN with RRC inactive assistance information.

[0008] There are two Connection Management (CM) states which are used to reflect the NAS signalling connectivity of the UE with the AMF: CM-IDLE CM-CONNECTED

[0009] A UE in CM-CONNECTED state has a NAS signalling connection with the AMF over the N1 reference point. When a UE is in e.g. CM-CONNECTED state, it can also be in RRC Inactive state. When in RRC Inactive state, at least one of the following applies: The UE reachability is managed by the RAN, with assistance information from the core network, and / or The UE paging is managed by the RAN, and / or The UE monitors for paging with the UE's CN (5G S-TMSI) and the RAN identifier.

[0010] 3GPP TS 23.501 V1.4.0 (2017-09) discloses the following in sections 5.3.3.2.5, 5.4.2 and 5.4.6 regarding CM-CONNECTED with RRC Inactive state, UE reachability in CM-CONNECTED and Core Network assisted RAN parameters tuning:CM-CONNECTED with RRC Inactive state

[0011] The RRC Inactive state applies to Next Generation-RAN (NG-RAN) (i.e. it applies to New Radio (NR) and E-UTRA connected to 5G CN).

[0012] The AMF, based on network configuration may provide assistance information to the NG RAN, to assist the NG RAN's decision whether the UE can be sent to RRC Inactive state. The UE may provide indication of support for RRC inactive state on NAS or AS layer.

[0013] The "RRC Inactive assistance information" comprises at least one of the following information: UE specific DRX values, and / or The Registration Area provided to the UE, and / or Periodic Registration Update timer, and / or If the AMF has enabled MICO mode for the UE, an indication that the UE is in MICO mode.

[0014] The RRC Inactive assistance information mentioned above is provided by the AMF during N2 activation with the (new) serving NG RAN node (i.e. during Registration, service request, handover) to assist the NG RAN's decision whether the UE can be sent to RRC Inactive state. RRC Inactive is part of a RRC state machine, and it is up to the RAN to determine the conditions to enter RRC Inactive state. If any of the parameters included in the RRC Inactive Assistance Information changes as the result of NAS procedure, the AMF shall update the RRC Inactive Assistance Information to the NG RAN node. When the UE is in CM-CONNECTED state, if the AMF has provided RRC Inactive assistance information, the RAN node may decide to move a UE to CM-CONNECTED with RRC Inactive state.

[0015] The state of the N2 and N3 reference points are not changed by the UE entering CM-CONNECTED with RRC Inactive state. A UE in RRC inactive state is aware of the RAN Notification area.

[0016] With the introduction of RRC inactive state, the UE reachability management is also moved down to RAN side in this state.UE reachability in CM-CONNECTED

[0017] For a UE in CM-CONNECTED state: The AMF knows the UE location on a serving (R)AN node granularity, and / or The NG-RAN notifies the AMF when UE becomes unreachable from a RAN point of view.

[0018] UE RAN reachability management is used by the RAN for UEs in RRC Inactive state. The location of a UE in RRC Inactive state is known by the RAN on a RAN Notification area granularity. A UE in RRC Inactive state is paged in cells of the RAN Notification area that is assigned to the UEs. The RAN Notification area can be a subset of cells configured in UE's Registration Area or all cells configured in the UE's Registration Area. The UE in RRC Inactive state performs Paging Area Update when entering a cell that is not part of the RAN Notification area that is assigned to the UE.

[0019] At transition into RRC Inactive state, the RAN configures the UE with a periodic RAN Notification Area Update timer value and the timer is restarted in the UE and in the RAN with this initial timer value. After the expiry of the periodic RAN Notification Area Update timer in the UE, the UE in RRC Inactive state performs periodic RAN Notification Area Update.

[0020] To aid the UE reachability management in the AMF, upon the expiry of the periodic RAN Notification Area Update timer in RAN, the RAN shall start an RRC release timer. If the RRC release timer expires, the RAN shall initiate the UE context release in the AN procedure.

[0021] The current 3GPP TS 23.501 V1.4.0 (2017-09) also indicated that some parameters may be provided by the 5GC to the RAN (see text below). However, this currently defined information (i.e. expected UE activity behaviour and expected HO behaviour) is not really related to the RAN paging.Core Network assisted RAN parameters tuning

[0022] The Core Network assisted RAN parameters tuning aids the RAN to minimize the UE state transitions and achieve optimum network behaviour. How the RAN uses the CN assistance information is not defined.

[0023] The CN assistance information may be derived by the AMF per UE in the AMF based on collection of UE behaviour statistics and / or other available information about the expected UE behaviour (such as subscribed DNN, SUPI ranges, or other information). If the communication pattern parameters of the UE are available, the AMF may use this information for selecting the CN assisted RAN parameter values. If the AMF is able to derive the Mobility Pattern of the UE, the AMF may take the Mobility Pattern information into account when selecting the CN assisted RAN parameter values.

[0024] The communication pattern parameters and the Mobility Pattern information are used by the AMF as input to derive the CN-assisted RAN parameter values. The communication pattern parameters can be provisioned by external party via the NEF. For the case of statistics-based CN assistance information collection, this may be enabled based on local configuration (e.g. subscribed DNN, SUPI ranges or other subscription information).

[0025] The CN assistance information provides the RAN with a way to understand the UE behaviour for these aspects: "Expected UE activity behaviour", i.e. the expected pattern of the UE's changes between CM-CONNECTED and CM-IDLE states. This may be derived e.g. from the statistical information, or mobility pattern or from subscription information. "Expected HO behaviour", i.e. the expected interval between inter-RAN handovers. This may be derived by the AMF e.g. from statistical information, or the Mobility Pattern information of the UE or the subscription information.

[0026] The AMF decides when to send this information to the RAN as "Expected UE behaviour" carried in N2 signalling over the N2 interface.

[0027] The calculation of the CN assistance information, i.e. the algorithms used and related criteria, and the decision when it is considered suitable and stable to send to the RAN may be vendor specific.

[0028] Document "Signalling flows for paging and resume for RRC_INACTIVE", Ericsson, 3GPP Tdoc R2-1700536 evaluates that regardless which solution is adopted for RAN notification areas, there is most likely a need to support the procedures described in the document. In this regard, the following proposal was made. Proposal 1: Consider the procedure discussed in this contribution in the work on defining the solution for RAN paging etc. in CN connected inactive state (RRC_INACTIVE).

[0029] Document "P-CR to 23.501 on SA2 impacts of RRC inactive mode and RAN paging", Qualcomm Incorporated, 3GPP Tdoc S2-170916 may be construed to disclose an evaluation of system impacts of RRC inactive mode feature, and proposes an amendment to TS 23.501. It is suggested to add a chapter on "CM-CONNECTED with RRC inactive mode". Said chapter defines, inter alia, that the UE may request a preference for using RRC inactive mode and parameters related to RRC inactive mode, e.g., RAN paging parameters preference. The AMF may decide, based on the UE provided preference over NAS for RRC inactive and its parameters, network configuration and subscription information, whether to enable or disable the RRC inactive mode feature. If the AMF decides to enable RRC inactive mode, the MME shall indicate to the RAN node that it has enabled RRC inactive mode feature by including an RRC inactive mode assistance information whenever radio bearers are established.

[0030] Document "TS 23.502 clarification for parameters of DNN", Huawei et.al., 3GPP Tdoc S2-176173 may be construed to disclose a clarification on the DSCP, 5QI, PPI, paging priority in network triggered service request procedure in 23.502. Inter alia, the document suggests Paging Priority indication (PPI) is included only: if the AMF receives a N11 message with an ARP priority level value associated with MPS or other priority services, as configured by the operator; One Paging Priority level can be used for multiple ARP priority level values. The mapping of ARP priority level values to Paging Priority level (or levels) is configured in AMF by operator policy. During a congestion situation, the (R)AN may prioritize the paging of UEs according to the Paging Priority indications.

[0031] Document "Discussion on Content of RAN Paging", CATT, 3GPP draft R3-173611 may be construed to disclose an evaluation of the content of RAN paging. The following observations and proposals were made. Observation 1: Assistance Data for Recommended Cells is not needed for RAN paging, the information could be provided to the target gNBs via the IE RAN Paging Area. Observation 2: Assistance Data for CE capable UEs is not needed for RAN paging. Observation 3: it's reasonable to support RAN paging repetition, anchor gNB responsible for the repetition and re-send the RAN paging to the other gNBs. Observation 4: Paging Attempt Information is not needed for RAN paging. Proposal 1: It's essential to prioritize RAN paging to guarantee the high priority services in case of massive UEs are under paging. Proposal 2: Paging priority should be generated by the anchor gNB and provided to the neighbor gNBs in the RAN paging message. Proposal 3: Remove the IE Assistance Data for Paging from RAN Paging. Proposal 4: Discuss and agree the stage 3 TP for RAN paging in section 5.SUMMARY

[0032] The present invention is defined in the independent claims. Preferred embodiments are defined in the dependent claims.

[0033] An objective of embodiments herein is therefore to obviate at least one of the above disadvantages and to provide improved paging.

[0034] According to a first aspect of the disclosure, there is provided a method performed by an Access and Mobility Management Function, AMF, for handling paging. The method comprises the AMF generating or receiving a message comprising paging assistance information; and transmitting, when triggered in case of at least one of downlink signaling and / or downlink data, the paging assistance information to an Access Network, AN, node; wherein the paging assistance information comprises service priority information.

[0035] According to a second aspect of the disclosure, there is provided a method performed by an Access Network, AN, node. The method comprises receiving paging assistance information from an Access and Mobility Management Function, AMF; determining a paging strategy based on the received paging assistance information; and paging the User Equipment, UE, using the determined paging strategy, wherein the UE to be paged is in Radio Resource Control, RRC, inactive state; wherein the paging assistance information comprises service priority information.

[0036] According to a third aspect of the disclosure, there is provided an Access and Mobility Management Function, AMF. The AMF is adapted to generate or receive a message comprising paging assistance information; and transmit, when triggered in case of at least one of downlink signaling and / or downlink data, the paging assistance information to an Access Network, AN, node; wherein the paging assistance information comprises service priority information.

[0037] According to a fourth aspect of the disclosure, there is provided an Access Network, AN, node. The AN node is adapted to receive paging assistance information from an Access and Mobility Management Function, AMF,; determine a paging strategy based on the received paging assistance information; and page the UE using the determined paging strategy, wherein the UE to be paged is in Radio Resource Control, RRC, inactive state; wherein the paging assistance information comprises service priority information.

[0038] According to a fifth aspect of the disclosure, there is provided a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to the first aspect or second aspect.

[0039] According to a sixth aspect of the disclosure, there is provided a carrier comprising the computer program of the fifth aspect, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

[0040] Whenever in the following disclosure any of the above-stated aspects (corresponding to the independent claims) is disclosed as "optional" (e.g., due to usage of conjunctive terms, such as "can", "may", "should", etc.), it is nevertheless to be read as "mandatory".

[0041] Thanks to the paging assistance information, the AN node has detailed and relevant information in order to be able to determine the paging strategy, i.e. the paging is improved.

[0042] Embodiments herein afford many advantages, of which a non-exhaustive list of examples follows: One advantage of the embodiments herein is that an optimized paging strategy can be formulated by Radio Access Network, RAN, based on its local info and information provided by 5GC in different procedures.

[0043] The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Hereinabove and in the following, "examples" pertain to principles underlying the claimed subject-matter and / or being useful for understanding the claimed subject-matter, "embodiments" pertain to the claimed subject-matter within the claim scope and "unclaimed examples" pertain to implementations not comprised by the claim scope. The embodiments, examples and unclaimed examples herein will now be further described in more detail in the following detailed description by reference to the appended drawings illustrating the embodiments and in which: Fig. 1 is a schematic drawing illustrating a 5G system according to an example of the present disclosure. Fig. 2 is a schematic drawing illustrating a 5G system according to an example of the present disclosure. Fig. 3 is a schematic drawing illustrating a communication system according to an example of the present disclosure. Fig. 4 is a signaling diagram illustrating a method according to an embodiment of the present disclosure. Fig. 5 is a flow chart illustrating a method performed by a CP node according to an embodiment of the present disclosure. Fig. 6 is a schematic drawing illustrating a CP node according to an embodiment of the present disclosure and according to an unclaimed example. Fig. 7 is a flow chart illustrating a method performed by an AN node according to an embodiment of the present disclosure. Fig. 8 is a schematic drawing illustrating an AN node according to an embodiment of the present disclosure and according to an unclaimed example.

[0045] The drawings are not necessarily to scale and the dimensions of certain features may have been exaggerated for the sake of clarity. Emphasis is instead placed upon illustrating the principle of the embodiments herein.DETAILED DESCRIPTION

[0046] Figure 3 is a schematic block diagram a system according to an example of the present disclosure. The system may in some examples apply to one or more radio access technologies such as for example Long Term Evolution (LTE), LTE Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications (GSM), 5G or any other Third Generation Partnership Project (3GPP) radio access technology, or other radio access technologies such as e.g. WLAN.

[0047] Figure 3 illustrates a User Equipment, UE, 101 which is adapted to communicate with an Access Network (AN) node 103. The AN node 103 is adapted to communicate with a Control Plane, CP, node 105.

[0048] The UE 101 may be a device by which a subscriber may access services offered by an operator's network and services outside operator's network to which the operator's radio access network and core network provide access, e.g. access to the Internet. The UE 101 may be any device, mobile or stationary, enabled to communicate in the communications network, for instance but not limited to e.g. user equipment, mobile phone, smart phone, sensors, meters, vehicles, household appliances, medical appliances, media players, cameras, Machine to Machine (M2M) device, Device to Device (D2D) device, Internet of Things (IoT) device or any type of consumer electronic, for instance but not limited to television, radio, lighting arrangements, tablet computer, laptop or Personal Computer (PC). The UE 101 may be portable, pocket storable, hand held, computer comprised, or vehicle mounted devices, enabled to communicate voice and / or data, via the radio access network, with another entity, such as another device or a server.

[0049] The AN node 103 may be referred to as a (R)AN node, a RAN node, a base station, a NodeB, an eNodeB (eNB), a gNB, a RNC etc.

[0050] The CP node 105 may also be referred to as a CP function, a CP entity, a node implementing a CP function or any other suitable term for a unit in a control plane. The CP node 105 may be for example a 5G CP node. The CP node 105 may be an Access and Mobility Management Function, AMF or a Radio AMF (RAMF).

[0051] The communication system exemplified in figure 3 may comprise other entities than the ones illustrated, but the UE 101, the AN node 103 and the CP node 105 are only illustrated for the sake of simplicity. For example, the communications system may comprise at least one of the entities illustrated in figures 1 and 2.

[0052] For the UE in RRC inactive state, RAN paging may be triggered in at least one of the following cases: a) In case of downlink signaling, and / or b) In case of downlink data.

[0053] When the RAN paging (i.e. paging of the UE) is executed, a certain paging strategy will be defined by the RAN. However, the RAN does not have all the information related to the UE (e.g. Critical level of the MT signaling) or information related to the PDU session (e.g. DNN, the critical level of the service) when applying the paging strategy in both cases above. The current 3GPP standard has not addressed the issue yet.

[0054] According to examples herein both static and dynamic paging assistance information is provided to the RAN in different procedures either at UE level or at PDU session level. At least part of the paging assistance information can be used by the RAN as input parameters when formulating a paging strategy when case a) and case b) happens for a UE in RRC in inactive state.

[0055] Static paging assistance information is static information when the UE context or the PDU session is established towards the RAN. It is valid for the live time of the UE context or the PDU session. Dynamic paging assistance information is formulated when the AMF indicates the critical level of the current activity, which shall only be used by the RAN for the current paging activity. The AMF formulates this information based on the input when the MT event happens (e.g. some priority information from other Network Functions (NF)).

[0056] Assistance information, also referred to as paging assistance information, paging information or inactive assistance information (these terms are used interchangeably herein) is transmitted from the 5GC to the RAN for a UE in RRC inactive state. The information is assistance information in the sense that it assists the AN node in determining the paging strategy. The paging assistance information may comprise at least one of the following parameters: Service priority information and / or paging priority information. The service priority information may comprise at least one of the following parameters: o Priority level (1-256, generated by the CP node (e.g. the AMF) based on different input), and / or o Attributes (dynamic (i.e. one time usage) vs. static), and / or o UE or PDU session level indication.

[0057] The paging priority information may correspond to the idle mode paging priority which much related to MPS priority service.

[0058] The paging assistance information may be provided from the AMF to the RAN in at least one of the following procedures: PDU session establishment / modification, and / or Downlink NAS transport, and / or N2 UE context establishment / modification, and / or HO preparation, and / or

[0059] Figure 4 is a signaling diagram illustrating a method according to an embodiment of the present disclosure, with reference to the system in the example of figure 3. The figure illustrates an embodiment of a paging assistance information delivery. The method illustrated in the embodiment of figure 4 comprises at least one of the following steps, which steps may be performed in any suitable order than described below:Step 401

[0060] The CP node 105 triggers a message to be transmitted to the AN node 103. The message may be a N2 message. An N2 message is a message to be transmitted over a N2 reference point. The N2 reference point may be between the CP node 105 and the AN node 103. The message may comprise information indicating modification of a PDU session resource. The UE 101 is in RRC inactive state when this step is performed.Step 402

[0061] The CP node 105 sends the triggered message to the AN node 103. The message may be a PDU session resource modification. The message comprises Paging assistance information. As mentioned above, the paging assistance information may comprise at least one of the following parameters: Service priority information and / or paging priority information. The service priority information comprises at least one of the following parameters: o Priority level (1-256, generated by AMF based on different input), and / or o Attributes (dynamic (i.e. one time usage) vs. static), and / or o UE or PDU session level indication.

[0062] The paging priority information may correspond to the idle mode paging priority which much related to MPS priority service.

[0063] The AN node 103 receives the message from the CP node 105.Step 403

[0064] The AN node 103 formulates a paging strategy for paging the UE 101.Step 404

[0065] The AN node 103 pages the UE 101 according to the strategy in step 403. In addition, a RRC resume procedure may also be initiated.

[0066] The method described above will now be described seen from the perspective of CP node 105. Figure 5 is a flowchart describing the method performed by the CP node 105, for handing paging, according to an embodiment of the present disclosure. The CP node 105 may be a 5G CP node. The CP node 105 may be an AMF. The method in the embodiment of figure 5 comprises at least one of the following steps to be performed by the CP node 105, which steps may be performed in any other suitable order than described below:Step 501

[0067] This step corresponds to step 401 in the embodiment of figure 4. The CP node 105 triggers that a UE 101 should be paged by an AN node 103. The UE 101 may be in RRC inactive state. The UE 101 may be in CM-Connected state with RRC inactive state.

[0068] The AN paging may be triggered in case of at least one of: downlink signaling and / or downlink data. Step 502

[0069] This step corresponds to step 402 in the embodiment of figure 4. The CP node 105 transmits, when triggered, paging assistance information to the AN node 103.

[0070] The paging assistance information may be transmitted to the AN node 103 in a message associated with at least one of the following procedures: PDU session establishment / modification, and / or Downlink NAS transport, and / or N2 UE context establishment / modification, and / or HO preparation.

[0071] The paging assistance information may comprise at least one of service priority information and / or paging priority information.

[0072] Service priority information comprised in the paging assistance information may comprise at least one of the following: Priority level (1-256, generated by the CP node (105), based on different input), and / or Attributes (dynamic (i.e. one time usage) vs static) , and / or UE or PDU session level indication.

[0073] The paging assistance information may comprise at least one of: static and / or dynamic paging assistance information.

[0074] The paging assistance information may be transmitted to the AN node 103 at UE level or at PDU session level.

[0075] To perform the method steps shown in the embodiment figure 5 for handling paging, the CP node 105 may comprise an arrangement as shown in the embodiment / unclaimed example of Figure 6. The CP node may be a 5G CP node. The CP node may be an AMF.

[0076] The CP node 105 is adapted to, e.g. according to an unclaimed example by means of a triggering module 601, trigger that a UE should be paged by an AN node. The UE may be in RRC inactive state. The UE may be in CM-Connected state with RRC inactive state. The triggering module 601 of the unclaimed example may be, however, a processor 602 comprised in the CP node 105 according to an embodiment.

[0077] The AN paging may be triggered in case of at least one of: downlink signaling and / or downlink data.

[0078] The CP node is adapted to, e.g. according to an unclaimed example by means of a transmitting module 603, transmit, when triggered, paging assistance information to the AN node.

[0079] The paging assistance information may be transmitted to the AN node in a message associated with at least one of the following procedures: PDU session establishment / modification, and / or Downlink NAS transport, and / or N2 UE context establishment / modification, and / or HO preparation.

[0080] The paging assistance information may comprise at least one of service priority information and / or paging priority information.

[0081] The service priority information comprised in the paging assistance information may comprise at least one of the following: Priority level (1-256, generated by the CP node (105), based on different input), and / or Attributes (dynamic (i.e. one time usage) vs static) , and / or UE or PDU session level indication.

[0082] The paging assistance information may comprise at least one of: static and / or dynamic paging assistance information.

[0083] The paging assistance information is transmitted to the AN node 103 at UE level or at PDU session level.

[0084] The CP node is adapted to, e.g. according to an unclaimed example by means of a receiving module 605, receive information and messages from other entities in the system.

[0085] In the embodiment, the CP node comprises the processor 602 and a memory 610. The memory 610 comprises instructions executable by the processor 602.

[0086] The memory 610 comprises one or more memory units. The memory 610 is arranged to be used to store data, received data streams, signalling, data, priority information, paging assistance information, paging strategy, local information, threshold values, time periods, configurations, schedul-ings, and applications to perform the methods herein when being executed in the CP node.

[0087] In the embodiment, a computer program may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the method steps in figures 4 and 5. A carrier may comprise the computer program, and the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

[0088] The method described above will now be described seen from the perspective of AN node 103. Figure 7 is a flowchart describing a method performed by the AN node for handing paging, according to an embodiment of the present disclosure. The method in the embodiment of figure 7 comprises at least one of the following steps to be performed by the AN node 103, which steps may be performed in any other suitable order than described below:Step 701

[0089] This step corresponds to step 402 in the embodiment of figure 4. The AN node 103 receives paging assistance information from a CP node.Step 702

[0090] This step corresponds to step 403 in the embodiment of figure 4. The AN node 103 determines a paging strategy based on the received paging assistance information. The paging strategy may also be referred to as a paging method, a paging procedure, a paging routine etc.

[0091] A paging strategy relates to how the AN node executes the paging in terms of: 1) The scope of the paging area (e.g. from small area to a big area, or paging in big area immediately). 2) A paging timer (e.g. waiting for the RRC resume from UE as paging response). 3) A paging repetition handling (how many repetitions before giving up). Step 703

[0092] This step corresponds to step 404 in the embodiment of figure 4. The AN node 103 pages the UE using the determined paging strategy.

[0093] To perform the method steps shown in figure 7 for handling paging, the AN node 103 may comprise an arrangement as shown in the embodiment / unclaimed example of Figure 8.

[0094] The AN node is adapted to, e.g. according to an unclaimed example by means of a receiving module 801, receive paging assistance information from a CP node. 34. The paging assistance information may be received by the AN node 103 in a message associated with at least one of the following procedures: PDU session establishment / modification, and / or Downlink NAS transport, and / or N2 UE context establishment / modification, and / or HO preparation.

[0095] The paging assistance information may comprise at least one of service priority information and / or paging priority information. The service priority information comprised in the paging assistance information may comprise at least one of the following: Priority level (1-256, generated by the CP node (105), based on different input), and / or Attributes (dynamic (i.e. one time usage) vs static) , and / or UE or PDU session level indication.

[0096] The paging assistance information may comprise at least one of: static and / or dynamic paging assistance information. The paging assistance information may be received by the AN node 103 at UE level or at PDU session level.

[0097] The AN node is adapted to, e.g. according to an unclaimed example by means of a determining module 803, determine a paging strategy based on the received paging assistance information. The determining module 803 according to the unclaimed example may, however, be a processor 805 according to the embodiment comprised in the AN node 103. The paging strategy may be determined further based on local information comprised in the AN node.

[0098] The AN node is adapted to, e.g. according to an unclaimed example by means of a paging module 808, page the UE using the determined paging strategy. 35. The UE 101 may be in RRC inactive state. The UE 101 may be in CM-Connected state with RRC inactive state.

[0099] The AN node is adapted to, e.g. according to an unclaimed example by means of a transmitting module 810, transmit messages and information to other nodes in the system such as e.g. the UE and / or the CP node 105.

[0100] In the embodiment, the AN node comprises the processor 801 and a memory 813. The memory 813 comprises instructions executable by the processor 801.

[0101] The memory 813 comprises one or more memory units. The memory 813 is arranged to be used to store data, received data streams, signalling, data, priority information, paging assistance information, paging strategy, local information, threshold values, time periods, configurations, schedul-ings, and applications to perform the methods herein when being executed in the AN node.

[0102] In the embodiment, a computer program may comprise instructions which, when executed on at least one processor, cause the at least one processor to carry out the method steps in figures 4 and 7. A carrier may comprise the computer program, and the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

[0103] The present mechanism for handling paging may be implemented through one or more processors, such as a processor 602 in the CP node arrangement depicted in Figure 6 and a processor 805 in the AN node arrangement depicted in Figure 8, together with computer program code for performing the functions of the embodiments herein. The processor may be for example a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC) processor, Field-programmable gate array (FPGA) processor or microprocessor. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into at least one of the CP node and / or the AN node. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code can furthermore be provided as pure program code on a server and downloaded to at least one of the CP node and / or the AN node.

[0104] The examples herein relate to RRC Inactive State Paging Assistance information delivery.

[0105] The embodiments herein are not limited to the above described embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the embodiments. A feature from one embodiment may be combined with one or more features of any other embodiment.

[0106] It should be emphasized that the term "comprises / comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It should also be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. The terms "consisting of" or "consisting essentially of" may be used instead of the term comprising.

[0107] The term "configured to" used herein may also be referred to as "arranged to", "adapted to", "capable of" or "operative to".

[0108] It should also be emphasised that the steps of the methods may, without departing from the embodiments herein, be performed in another order than the order in which they appear.

Claims

1. A method performed by an Access and Mobility Management Function, AMF, (105), for handling paging, the method comprising: the AMF generating a message comprising paging assistance information; and transmitting (402, 502), when triggered in case of at least one of downlink signaling and / or downlink data, the paging assistance information to an Access Network, AN, node (103); wherein the paging assistance information comprises paging priority information, and wherein a User Equipment, UE, (101) to be paged is in Radio Resource Control, RRC, inactive state; wherein the message comprising the paging assistance information is a UE context modification message configured to cause the AN node to modify the paging priority information to an established UE context associated with the UE.

2. The method according to claim 1, wherein: the paging assistance information comprises (i) service priority information comprising attributes for dynamic one time usage and (ii) dynamic paging assistance information formulated when the AMF indicates a critical level of a current activity only to be used by a Radio Access Network, RAN, for a current paging activity.

3. The method according to any of the preceding claims, wherein the UE (101) is in Connection Management-, CM-, Connected state with RRC inactive state.

4. The method according to claim 2 or 3, wherein service priority information comprised in the paging assistance information further comprises at least one of: - Priority level, generated by the AMF (105); and / or - UE or PDU session level indication.

5. The method according to any of the preceding claims, wherein the paging assistance information is transmitted to the AN node (103) at UE level or at PDU session level.

6. A method performed by an Access Network, AN, node (103), the method comprising: receiving (402, 701) a message comprising paging assistance information from an Access and Mobility Management Function, AMF, (105); determining (403, 702) a paging strategy based on the received paging assistance information; and paging (404, 703) a User Equipment, UE, (101) using the determined paging strategy, wherein the UE (101) to be paged is in Radio Resource Control, RRC, inactive state; wherein the paging assistance information comprises paging priority information; wherein the message comprising the paging assistance information is a UE context modification message configured to cause the AN node to modify the paging priority information to an established UE context associated with the UE.

7. The method according to claim 6, wherein: the paging assistance information comprises (i) service priority information comprising attributes for dynamic one time usage and (ii) dynamic paging assistance information formulated when the AMF indicates a critical level of a current activity only to be used by a Radio Access Network, RAN, for a current paging activity.

8. The method according to claim 6 or 7, wherein the paging strategy is determined further based on local information comprised in the AN node (103).

9. The method according to any of claims 6 to 8, wherein the UE (101) is in Connection Management-, CM-, Connected state with RRC inactive state.

10. The method according to any of claims 6 to 9, wherein service priority information comprised in the paging assistance information further comprises at least one of: - Priority level, generated by the AMF (105); and / or - UE or PDU session level indication.

11. The method according to any of claims 6 to 10, wherein the paging assistance information is received by the AN node (103) at UE level or at PDU session level.

12. An Access and Mobility Management Function, AMF, (105), the AMF (105) being adapted to: generate a message comprising paging assistance information; and transmit, when triggered in case of at least one of downlink signaling and / or downlink data, the paging assistance information to an Access Network, AN, node (103); wherein the paging assistance information comprises paging priority information, and wherein a User Equipment, UE, (101) to be paged is in Radio Resource Control, RRC, inactive state; wherein: wherein the message comprising the paging assistance information is a UE context modification message configured to cause the AN node to modify the paging priority information to an established UE context associated with the UE.

13. The AMF (105) according to claim 12, wherein the AMF is further adapted to perform the method of any one of claims 2 to 5.

14. An Access Network, AN, node (103), the AN node (103) being adapted to: receive a message comprising paging assistance information from an Access and Mobility Management Function, AMF, (105); determine a paging strategy based on the received paging assistance information; and page a UE (101) using the determined paging strategy, wherein the UE (101) to be paged is in Radio Resource Control, RRC, inactive state; wherein the paging assistance information comprises paging priority information; wherein: wherein the message comprising the paging assistance information is a UE context modification message configured to cause the AN node to modify the paging priority information to an established UE context associated with the UE.

15. The AN node (103) according to claim 14, wherein the AN node (103) is further adapted to perform the method of any one of claims 7 to 11.

16. A computer program comprising instructions which, when executed on at least one processor (602, 805), cause the at least one processor to carry out the method according to any one of claims 1 to 11.

17. A carrier comprising the computer program of claim 16, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium (610, 813).