Methods and apparatuses for lawful interception

Abstract

Methods and apparatuses for lawful interception (LI) are disclosed. According to an embodiment, a first network node implementing session management determines whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network. The first network node sends, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

Description

METHODS AND APPARATUSES FOR LAWFUL INTERCEPTIONTECHNICAL FIELD

[0001] Embodiments of the disclosure generally relate to communication, and, more particularly, to methods and apparatuses for lawful interception (LI).BACKGROUND

[0002] This section introduces aspects that may facilitate better understanding of the present disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

[0003] Currently, a group of specifications including 3rd generation partnership project (3GPP) technical specification (TS) 33.126 V19.0.0, 33.127 V18.7.0, 33.128 V18.7.0 and European telecommunications standards institute (ETSI) TS 103 221-1 VI.17.1, 103 221- 2 VI.6.1 describe how network function (NF) in 5th generation core (5GC) network intercepts protocol data unit (PDU) session of one certain task, which is provisioned by administration function (ADMF).

[0004] 3GPP TS 33.126 V19.0.0 illustrates the lawful interception requirements. TS 33.127 V18.7.0 presents the architecture and functions. TS 33.128 V18.7.0 elaborates the details including protocols of lawful interception (LI) procedures. ETSI TS 103 221-1 VI.17.1 and 103 221-2 VI.6.1 separately describe the details of LI_X1 and LI_X2 / X3 interface. For the packet core network functions, such as access and mobility management function (AMF) and session management function (SMF), they should support to receive provision command from ADMF via LI Xl interface, report interception related information (IRI) events to mediation and delivery function 2 (MDF2) via LI X2 interface and user plane function (UPF) should report communication content (CC) to MDF3 via LI X3 interface.SUMMARY

[0005] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intendedto identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] One of the objects of the disclosure is to provide an improved solution for lawful interception (LI). In particular, one of the problems to be solved by the disclosure is that currently there is no solution for achieving LI service scoping for international roaming. Another problem to be solved by the disclosure is that hanging session and unidentifiable protocol data unit (PDU) session modification or release interception related information (IRI) events may occur in mediation and delivery function (MDF) in some cases.

[0007] According to a first aspect of the disclosure, there is provided a method at a first network node implementing session management. The method may comprise determining whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network. The method may further comprise sending, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

[0008] With the above first aspect, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the second network node to avoid problems such as hanging session and unidentifiable PDU session modification or release IRI events.

[0009] In an embodiment of the disclosure, the second network node may comprise an MDF. Sending one or more messages for stopping the LI reporting for the target may comprise sending a first message indicating that a PDU session has been modified for the target. The first message may comprise a first indicator indicating that the target has roamed out. Alternatively, sending one or more messages for stopping the LI reporting for the target may comprise sending a second message indicating that an interception is stopped for the target. Alternatively, sending one or more messages for stopping the LI reporting for the target may comprise sending a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDUsession has been released for the target. The fourth message may be sent after the third message.

[0010] In an embodiment of the disclosure, the second network node may comprise a user plane node. Sending one or more messages for stopping the LI reporting for the target may comprise sending a fifth message for deactivating an interception for the target.

[0011] In an embodiment of the disclosure, the second network node may comprise an MDF. Sending one or more messages for starting the LI reporting for the target may comprise sending a sixth message indicating that a PDU session has been modified for the target. The sixth message may comprise a fifth indicator indicating that the target has roamed back. Alternatively, sending one or more messages for starting the LI reporting for the target may comprise sending a seventh message indicating that an interception is started for the target. The seventh message may comprise a sixth indicator indicating that a cause of starting of the interception is roaming back of the target. Alternatively, sending one or more messages for starting the LI reporting for the target may comprise sending an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target. The ninth message may be sent after the eighth message.

[0012] In an embodiment of the disclosure, the second network node may comprise a user plane node. Sending one or more messages for starting the LI reporting for the target may comprise sending a tenth message for activating an interception for the target.

[0013] In an embodiment of the disclosure, when a mobile country code (MCC) in a permanent identifier of a subscriber associated with the target is different from an MCC of a serving network of the target and another network node implementing session management is inserted in a visiting network of the target, it may be determined that the target has roamed out internationally from the home network to the visiting network.

[0014] In an embodiment of the disclosure, when the MCC in the permanent identifier of the subscriber associated with the target is same as the MCC of the serving network of the target and the another network node implementing session management is removed from the visiting network, it may be determined that the target has roamed back from the visiting network to the home network.

[0015] According to a second aspect of the disclosure, there is provided a method at an MDF. The method may comprise receiving, from a first network node implementing session management, one or more messages for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The method may further comprise sending, to a law enforcement monitoring facility (LEMF), a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

[0016] With the above second aspect, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the MDF to avoid problems such as hanging session and unidentifiable PDU session modification or release IRI events.

[0017] In an embodiment of the disclosure, receiving one or more messages for stopping the LI reporting for the target may comprise receiving a first message indicating that a PDU session has been modified for the target. The first message may comprise a first indicator indicating that the target has roamed out. Alternatively, receiving one or more messages for stopping the LI reporting for the target may comprise receiving a second message indicating that an interception is stopped for the target. Alternatively, receiving one or more messages for stopping the LI reporting for the target may comprise receiving a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDU session has been released for the target. The fourth message may be received after the third message.

[0018] In an embodiment of the disclosure, receiving one or more messages for starting the LI reporting for the target may comprise receiving a sixth message indicating that a PDU session has been modified for the target. The sixth message may comprise a fifth indicator indicating that the target has roamed back. Alternatively, receiving one or more messages for starting the LI reporting for the target may comprise receiving a seventh message indicating that an interception is started for the target. The seventh message may comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target. Alternatively, receiving one or more messages for starting the LIreporting for the target may comprise receiving an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target. The ninth message may be received after the eighth message.

[0019] According to a third aspect of the disclosure, there is provided a method at a user plane node. The method may comprise receiving, from a first network node implementing session management, a message for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The method may further comprise stopping or starting the LI reporting for the target according to the received message.

[0020] With the above third aspect, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for MDF3 to avoid problems such as hanging session.

[0021] In an embodiment of the disclosure, the message for stopping the LI reporting for the target may comprise a fifth message for deactivating an interception for the target.

[0022] In an embodiment of the disclosure, the message for starting the LI reporting for the target may comprise a tenth message for activating an interception for the target.

[0023] According to a fourth aspect of the disclosure, there is provided a method at an LEMF. The method may comprise receiving, from an MDF, a report message indicating that LI reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network.

[0024] With the above fourth aspect, a solution can be provided to achieve LI service scoping for international roaming.

[0025] According to a fifth aspect of the disclosure, there is provided a first network node implementing session management. The first network node may comprise at least one processor and at least one memory. The at least one memory may contain instructions executable by the at least one processor, whereby the first network node may be operativeto determine whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network. The first network node may be further operative to send, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

[0026] In an embodiment of the disclosure, the first network node may be operative to perform the method according to the above first aspect.

[0027] According to a sixth aspect of the disclosure, there is provided an MDF. The MDF may comprise at least one processor and at least one memory. The at least one memory may contain instructions executable by the at least one processor, whereby the MDF may be operative to receive, from a first network node implementing session management, one or more messages for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The MDF may be further operative to send, to an LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

[0028] In an embodiment of the disclosure, the MDF may be operative to perform the method according to the above second aspect.

[0029] According to a seventh aspect of the disclosure, there is provided a user plane node. The user plane node may comprise at least one processor and at least one memory. The at least one memory may contain instructions executable by the at least one processor, whereby the user plane node may be operative to receive, from a first network node implementing session management, a message for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The user plane node may be further operative to stop or start the LI reporting for the target according to the received message.

[0030] In an embodiment of the disclosure, the user plane node may be operative to perform the method according to the above third aspect.

[0031] According to an eighth aspect of the disclosure, there is provided an LEMF. The LEMF may comprise at least one processor and at least one memory. The at least one memory may contain instructions executable by the at least one processor, whereby the LEMF may be operative to receive, from an MDF, a report message indicating that LI reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network.

[0032] In an embodiment of the disclosure, the LEMF may be operative to perform the method according to the above fourth aspect.

[0033] According to a ninth aspect of the disclosure, there is provided a computer program product. The computer program product may comprise instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of the above first to fourth aspects.

[0034] According to an tenth aspect of the disclosure, there is provided a computer readable storage medium. The computer readable storage medium may store thereon instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of the above first to fourth aspects.

[0035] According to an eleventh aspect of the disclosure, there is provided a first network node implementing session management. The first network node may comprise a determination module for determining whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network. The first network node may further comprise a sending module for sending, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

[0036] According to a twelfth aspect of the disclosure, there is provided an MDF. The MDF may comprise a reception module for receiving, from a first network nodeimplementing session management, one or more messages for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The MDF may further comprise a sending module for sending, to an LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

[0037] According to a thirteenth aspect of the disclosure, there is provided a user plane node. The user plane node may comprise a reception module for receiving, from a first network node implementing session management, a message for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The user plane node may further comprise a control module for stopping or starting the LI reporting for the target according to the received message.

[0038] According to a fourteenth aspect of the disclosure, there is provided an LEMF. The LEMF may comprise a reception module for receiving, from an MDF, a report message indicating that LI reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network.

[0039] According to a fifteenth aspect of the disclosure, there is provided a method implemented in a communication system. The communication system may include two or more of: a first network node implementing session management, an MDF, a user plane node and an LEMF. The method may comprise steps of two or more of the methods according to the above first to fourth aspects.

[0040] According to a sixteenth aspect of the disclosure, there is provided a communication system. The communication system may include two of more of: a first network node implementing session management according to the above fifth or eleventh aspect; an MDF according to the above sixth or twelfth aspect; a user plane node accordingto the above seventh or thirteenth aspect; and an LEMF according to the above eighth or fourteenth aspect.

[0041] According to any aspect of the disclosure, in some embodiments, the second message may comprise a second indicator indicating that a cause of stopping of the interception is roaming out of the target.

[0042] According to any aspect of the disclosure, in some embodiments, the second message may comprise one or more of: a permanent identifier of a subscriber associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device associated with the PDU session involved in the interception; a generic public identifier of the subscriber associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a packet data network (PDN) connection involved in the interception.

[0043] According to any aspect of the disclosure, in some embodiments, the details about the PDN connection may comprise one or more of: evolved packet system (EPS) subscriber identities associated with the PDN connection; a fourth indicator indicating whether an international mobile subscriber identity (IMSI) in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection.

[0044] According to any aspect of the disclosure, in some embodiments, the first message may be an LI X2 IRI message containing a record about PDU session modification.

[0045] According to any aspect of the disclosure, in some embodiments, the second message may be anew LI X2 IRI message containing a record about stop of interception.

[0046] According to any aspect of the disclosure, in some embodiments, the third message may be an LI X2 IRI message containing a record about PDU session modification, and the fourth message may be an LI X2 IRI message containing a record about PDU session release.

[0047] According to any aspect of the disclosure, in some embodiments, the fifth message may be an LI T3 Deactivate Task message.

[0048] According to any aspect of the disclosure, in some embodiments, the sixth message may be an LI X2 IRI message containing a record about PDU session modification.

[0049] According to any aspect of the disclosure, in some embodiments, the seventh message may be an LI X2 IRI message containing a record about start of interception.

[0050] According to any aspect of the disclosure, in some embodiments, the eighth message may be an LI X2 IRI message containing a record about PDU session establishment, and the ninth message may be an LI X2 IRI message containing a record about PDU session modification.

[0051] According to any aspect of the disclosure, in some embodiments, the tenth message may be an LI T3 Activate Task message.

[0052] According to any aspect of the disclosure, in some embodiments, the first or fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back.

[0053] According to any aspect of the disclosure, in some embodiments, the second or sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target.

[0054] According to any aspect of the disclosure, in some embodiments, the first network node may comprise one of: a session management function (SMF); and a packet data network gateway control plane (PGW-C).

[0055] According to any aspect of the disclosure, in some embodiments, the user plane node may comprise one of: a user plane function (UPF); and a packet data network gateway user plane (PGW-U).

[0056] According to any aspect of the disclosure, in some embodiments, the report message indicating that the LI reporting for the target is stopped may be an IRI message having an IRI type set to END.

[0057] According to any aspect of the disclosure, in some embodiments, the report message indicating that the LI reporting for the target is started may be an IRI message having an IRI type set to BEGIN.

[0058] According to some embodiment(s) of the disclosure, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the second network node to avoid problems such as hanging session and unidentifiable PDU session modification or release IRI events.BRIEF DESCRIPTION OF THE DRAWINGS

[0059] These and other objects, features and advantages of the disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which are to be read in connection with the accompanying drawings.

[0060] FIGs. 1A and IB are flowcharts illustrating a process in a first roaming scenario;

[0061] FIGs. 2A and 2B are flowcharts illustrating a process in a second roaming scenario;

[0062] FIG. 3 is a diagram illustrating an exemplary LI architecture in which an embodiment of the disclosure is applicable;

[0063] FIG. 4 is a diagram illustrating an exemplary communication system into which an embodiment of the disclosure is applicable;

[0064] FIGs. 5A-5C are flowcharts each illustrating a process according to an embodiment of the disclosure;

[0065] FIGs. 6A-6C are flowcharts each illustrating a process according to an embodiment of the disclosure;

[0066] FIG. 7 is a flowchart illustrating a method performed by a first network node according to an embodiment of the disclosure;

[0067] FIGs. 8A-8C are flowcharts for explaining the method of FIG. 7;

[0068] FIG. 9 is a flowchart for explaining the method of FIG. 7 ;

[0069] FIGs. 10 A- 10C are flowcharts for explaining the method of FIG. 7;

[0070] FIG. 11 is a flowchart for explaining the method of FIG. 7;

[0071] FIG. 12 is a flowchart illustrating a method performed by an MDF according to an embodiment of the disclosure;

[0072] FIGs. 13A-13C are flowcharts for explaining the method of FIG. 12;

[0073] FIGs. 14A-14C are flowcharts for explaining the method of FIG. 12;

[0074] FIG. 15 is a flowchart illustrating a method performed by a user plane node according to an embodiment of the disclosure;

[0075] FIG. 16 is a flowchart illustrating a method performed by an LEMF according to an embodiment of the disclosure;

[0076] FIGs. 17A and 17B are flowcharts illustrating an exemplary process according to an embodiment of the disclosure;

[0077] FIGs. 18A and 18B are flowcharts illustrating an exemplary process according to an embodiment of the disclosure;

[0078] FIG. 19 is a flowchart illustrating an exemplary process according to an embodiment of the disclosure;

[0079] FIG. 20 is a block diagram illustrating an apparatus suitable for use in practicing some embodiments of the disclosure;

[0080] FIG. 21 is a block diagram illustrating a first network node according to an embodiment of the disclosure;

[0081] FIG. 22 is a block diagram illustrating an MDF according to an embodiment of the disclosure;

[0082] FIG. 23 is a block diagram illustrating a user plane node according to an embodiment of the disclosure; and

[0083] FIG. 24 is a block diagram illustrating an LEMF according to an embodiment of the disclosure.Detailed Description

[0084] For the purpose of explanation, details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed. It is apparent, however, to those skilled in the art that the embodiments may be implemented without these specific details or with an equivalent arrangement.

[0085] 3GPP TS 33.126 V19.0.0, 33.127 V18.7.0 and 33.128 V18.7.0 also describe how network element (NE) reporting interception related information (IRI) events for 5th generation (5G) session in non-roaming and home-routed roaming scenarios. Home-routed roaming enables a user equipment (UE) to use services in the home public land mobile network (HPLMN) when the UE is in a visiting public land mobile network (VPLMN). The VPLMN is the network where the UE is located and the HPLMN is the network where the subscription profile of the user is preserved.

[0086] Considering international roaming, the standard has some requirements. The requirement “R6.3 - 170” in clause 6.3 of 3GPP TS 33.126 V19.0.0 is as below: Outbound Roaming Home Network - CSPs shall be able to intercept its outbound roamers, if the communication pass through the home CSP’s network. The term CSP refers to communication service provider. The requirement “R6.5 - 20” in clause 6.5 of 3GPP TS 33.126 V19.0.0 highlights that “the CSP shall be able to both suspend (e.g. when roaming outbound internationally) and resume all or a portion of the obligated Interception Product during the Interception Period.” The requirement “R6.5 - 40” in clause 6.5 of 3GPP TS 33.126 V19.0.0 is as below: LI Changes - The CSP shall be able to notify the LEA of changes related to interception (e.g., suspend or resume). The term LEA refers to law enforcement agency. In addition, 3GPP TS 33.128 V18.7.0 requires to stop interception when the target is roaming outbound internationally (see clause 4.4.6 thereof). However, how to suspend and resume the interception has not been explained.

[0087] There are different lawful intercept specifications including 3GPP standards and ETSI standards for 4G network and 5G network till now. Nowadays, home routed roaming (HR-roaming) is a very important requirement for network function (NF) in the network. According to the standard TS 33.128 V18.7.0, the service scope is introduced, and the CSP shall be able to both suspend (e.g. when roaming outbound internationally) and resume all or a portion of the obligated Interception Product during the Interception Period based on different country’s national regulations. However, the method used to achieve the roaming related service scoping is not described in current standards.

[0088] For HR roaming, there will be visiting session management function (V-SMF) in visiting core network and home SMF (H-SMF) in home core network. If stopping interception is required based on national regulations, H-SMF should not report any IRIevent via LI X2 interface and home user plane function (H-UPF) should not report any communication content (CC) via LI X3 interface when roaming outbound internationally.

[0089] There are some cases which will cause unpaired reporting for home mediation and delivery function 2 (MDF2) and MDF3. The unpaired message will cause confusing of MDF2 and MDF3.

[0090] FIGs. 1A and IB illustrate a process in a first roaming scenario. In this scenario, a protocol data unit (PDU) session is established in non-roaming case, and then the UE moves to visiting PLMN and releases the PDU session. At step 1, an access and mobility management function (AMF) sends Nsmf_PDUSession_CreateSMContext Request message to an SMF. The request creates an individual session management context for a given PDU session. At step 2, the SMF sends Nsmf_PDUSession_CreateSMContext Response message to the AMF. At step 3, the SMF sends Namf_Communication_ EBIAssignment Request to the AMF for EPS bearer identity (EBI), where EPS refers to evolved packet system. The AMF sends Response message to the SMF, containing the assigned EBI or EBIs. At step 4, the SMF sends PFCP Session Establishment Request message to a UPF to allocate the core network (CN) tunnel, where PFCP refers to packet forwarding control protocol. The UPF sends Response message to the SMF. At step 5, the SMF sends Namf_Communication_NlN2MessageTransfer Request message to the AMF, including N1 PDU Session Establishment Accept and N2 PDU Session Resource Setup Request Transfer messages. The AMF sends Response message to the SMF. At step 6, the SMF reports LI_X2 PDU session establishment to an MDF2. At step 7, the AMF sends Nsmf_PDUSession_UpdateSMContext Request message to the SMF with N2 PDU Session Resource Setup Response Transfer message. At step 8, the SMF sends PFCP Session Modification Request message to the UPF to update F-TEID of the radio access network (RAN), where F-TEID refers to fully qualified tunnel endpoint identifier. The UPF sends PFCP Session Modification Response message to the SMF. At step 9, the SMF responds with Nsmf_PDUSession_UpdateSMContext Response message to the AMF. At step 10, the SMF reports LI_X2 PDU session modification to the MDF2.

[0091] At step 11, when the user is roaming out to another country, a visiting SMF (V- SMF) sends Nsmf_PDUSession_Create Request to the home SMF (H-SMF). At step 12, the H-SMF sends PFCP session modification request to the home UPF (H-UPF). The H-UPF sends Response message to the H-SMF. At step 13, the H-SMF sends Nsmf_ PDUSession_Create Response to the V-SMF. At step 14, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends Response message to the H-SMF. At step 15, the V-SMF sends Nsmf_PDUSession_Update Request with upCnxState Activated to the H-SMF. The H-SMF sends Response message to the V-SMF. At step 16, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends Response message to the H-SMF.

[0092] Then, the UE triggers PDU session release in HR-roaming cases. In HR-roaming cases, the V-SMF is defined as an SMF serving the PDU session in the VPLMN. The H- SMF is an SMF serving the PDU session in the HPLMN. At step 17, the V-SMF sends Nsmf_PDUSession_Update Request message to the H-SMF and the requestindication is set to REL_DUE_TO_5G_AN_REQUEST to indicate that the PDU session resource has been released by 5G access network (AN). The H-SMF sends Response message to the V- SMF. At step 18, the H-SMF sends PFCP session release request to the H-UPF. The H- UPF sends Response message to the H-SMF. At step 19, the H-SMF sends Nsmf_PDUSession_Update Request message to the V-SMF and the requestindication is set to NW REQ PDU SES REL (network-requested PDU session release). The V-SMF sends Response message to the H-SMF. At step 20, the V-SMF sends Nsmf_PDUSession_StatusNotify Request message to the H-SMF. The H-SMF sends Response message to the V-SMF.

[0093] Therefore, in the above first scenario, a PDU session is established in non-roaming case. Then the UE moves to visiting PLMN and the V-SMF is inserted. Thus, the H-SMF knows that the UE is roaming out. Then if the PDU session is released in the VPLMN, then there will be no reporting to home MDF2 and MDF3 according to the requirements mentioned above with respect to international roaming. As a result, there may be a hanging session in the home MDF2 and MDF3.

[0094] FIGs. 2A and 2B illustrate a process in a second roaming scenario. In this scenario, a PDU session is established in HR roaming case, and then the UE moves to home PLMN and releases the PDU session. At step 1, a V-SMF sends Nsmf_PDUSession_ Create Request message to an H-SMF. At step 2, the H-SMF sends Nsmf_PDUSession_Update Request message to the V-SMF. At step 3, the V-SMF sends Nsmf_PDUSession_UpdateResponse message to the H-SMF. At step 4, the H-SMF sends PFCP session establishment request to an H-UPF. The H-UPF sends Response message to the H-SMF. At step 5, the H-SMF sends Nsmf_PDUSession_Create Response message to the V-SMF.

[0095] Then, the UE moves from VPLMN to HPLMN, and the V-SMF is removed. At step 6, an AMF sends Nsmf_PDUSession_CreateSMContext Request to the H-SMF. At step 7, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends Response message to the H-SMF. At step 8, the H-SMF sends Nsmf_ PDUSession_CreateSMContext Response to the AMF. At step 9, the AMF sends Nsmf_ PDUSession UpdateSMContext Request to the H-SMF. At step 10, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends Response message to the H-SMF. At step 11, the H-SMF sends Nsmf_PDUSession_UpdateSMContext Response to the AMF. At step 12, the H-SMF sends LI X2 IRI event to an MDF2 to indicate start of interception due to roaming back. At step 13, the H-SMF sends N4 modification request to the H-UPF. The H-UPF sends Response message to the H-SMF.

[0096] Then, the UE releases the PDU session. At step 14, the AMF sends Nsmf_PDUSession_UpdateSMContext Request to the SMF to release PDU session. At step 15, the SMF sends PFCP session release request to the UPF. The UPF sends Response message to the SMF. At step 16, the SMF sends Nsmf_PDUSession_ UpdateSMContext Response to AMF. At step 17, the AMF sends Nsmf_PDUSession_ UpdateSMContext Request with N2 info to the SMF. The SMF sends Response message to the AMF. At step 18, the AMF sends Nsmf_PDUSession_UpdateSMContext Request with N1 info to the SMF. The SMF sends Response message to the AMF. At step 19, the SMF sends Nsmf_PDUSession_SMContextStatusNotify Request with resource status being released to the AMF. At step 20, the AMF replies with Nsmf_PDUSession_ SMContextStatusNotify Response to the SMF. At step 21, the SMF reports LI_X2 PDU session release to the MDF2.

[0097] Therefore, in the above second scenario, if a PDU session is established in HR roaming case, the H-SMF does not report LI X2 PDU session establishment event because the use is in visiting core network. When the UE moves from VPLMN to HPLMN, then the H-SMF becomes the SMF handling non-roaming session. Here, there will be LI X2modification / release events, which may not be recognized by MDF2 and MDF3 since the PDU session establishment has not been reported before.

[0098] The present disclosure proposes an improved solution for lawful interception. In particular, to support lawful intercept service scoping function for international roaming, the present disclosure proposes a solution for POI NF in HPLMN to stop interception when user is roaming out to visiting network in different country and restart interception when user is roaming back to home network. This is applicable for NFs in core networks, including SMF, UPF, etc. It can fulfill the standards requirement and help MDFx (e.g. MDF2, MDF3) to avoid hanging session and unidentifiable PDU session modification or release IRI events. Hereinafter, the solution will be described in detail with reference to FIG. 3 to FIG. 24.

[0099] FIG. 3 illustrates an exemplary LI architecture in which an embodiment of the disclosure is applicable. As shown in FIG. 3, the architecture may comprise a system information retrieval function (SIRF) 310, an administration function (ADMF) 320, a triggering function (TF) 330, points of interception (POIs) 340-1, 340-2, a mediation and delivery function (MDF) 350, a law enforcement monitoring facility (LEMF) 360, and a law enforcement agency (LEA) 370. The LEMF 360 and the LEA 370 are in LEA domain, while the other components of the architecture are in communication service provider (CSP) domain.

[0100] In general, the LEA 370 may be responsible for submitting a warrant for lawful interception to the CSP, although in some countries the warrant may be provided by a different legal entity (e.g. judiciary).

[0101] The ADMF 320 may provide the CSP’s administrative and management functions for the LI capability. This may include overall responsibility for the provisioning / activating, modifying, and de-activating / de-pro visioning the POI(s), TF, and the MDF. The AMDF may include two logical functions: an LI control function (LICF) 322 and an LI provisioning function (LIPF) 321. Within one ADMF 320, there is one LICF 322, and at least one, but possibly multiple LIPFs 321. The LIPF 321 may provision all the applicable POIs, TFs and MDFs. The LICF 322 may control the management of the end- to-end life cycle of a warrant.

[0102] The SIRF 310 may be responsible for providing the LIPF 321 with the system related information for network functions (NFs) that are known by the SIRF (e.g. service topology). The information provided can allow the LIPF / LICF to perform the necessary operations to establish and maintain interception of the target service (e.g. provisioning POIs, TFs and MDFs over LI Xl).

[0103] The TF 330 may be provisioned by the LIPF 321 and may be responsible for triggering triggered POIs, in response to network and service events matching the criteria provisioned by the LIPF 321. The TF 330 may detect the target communications and sends a trigger to the associated triggered POI 340-1.

[0104] The POI 340-1 / 340-2 may detect the target communication, derive the intercept related information (IRI) or communication content (CC) from the target communications and deliver the POI output as xIRI to an MDF2 or as xCC to an MDF3. The output of a POI may be determined by the type of the NF associated with the POI. A POI may be embedded within an NF or separate from an NF with which it is associated.

[0105] The MDF 350 may deliver interception product to the LEMF 360. Two variations of MDF are defined: MDF2 and MDF3. MDF2 may generate the IRI messages from the xIRI and send them to one or more LEMFs 360. The MDF3 may generate the CC from the xCC and deliver it to one or more intercepting LEMFs 360.

[0106] FIG. 4 illustrates an exemplary communication system into which an embodiment of the disclosure is applicable. In this communication system, portions of the architecture of FIG. 3 are mapped to certain network functions of a 5G core network. In this case, a target (e.g. a subscriber / user and / or a UE / terminal device) of lawful interception is served by the 5G core network. As shown in FIG. 4, the communication system may comprise an LEA 370, an ADMF 320, a session management function (SMF) 480, a user plane function (UPF) 490, an MDF 350, and an LEMF 360. The ADMF 320 may include an LIPF 321 and an LICF 322 as described above. The interface between the LEA 370 and the LICF 322 is LI HI1. The interface between the LICF 322 and the LIPF 321 is LI ADMF.

[0107] The SMF 480 handles control plane actions (e.g. establishing, modifying, deleting) for PDU sessions and may include an IRI -POI 481 that has the LI capability to generate related xIRI. The UPF 490 handles the user plane data and may include a CC-POI491 that has the capability to duplicate the user plane packets from the PDU sessions based on the interception rules received from the SMF 480. When interception of communication contents is required, the CC-TF 482 in the SMF 480 may send a trigger to the CC-POI 491 in the UPF 490 over LI T3 interface to trigger POI interception.

[0108] The MDF 350 may include an MDF2 351 and an MDF3 352 as described above. The interface between the MDF2 351 and the MDF3 352 is LI MDF. The MDF2 351 interfaces with the SMF 480 via LI X2 interface and with the LEMF via LI HI2 interface. The MDF3 352 interfaces with the UPF 490 via LI X3 interface and with the LEMF via LI HI3 interface.

[0109] The LIPF 321 in the ADMF 320 may provision the POI(s), the MDF2351 and the MDF3 352 over LI Xl interfaces. The ADMF 320 interfaces with the POIs and TFs in the SMF 480 via LI Xl interface to provide LI target information on the POIs and TFs to intercept target communications. A POI NF, for example the SMF 480, may report LI_X2 IRI event to the MDF2 351 when PDU session establishment, modification, release happens. LI Xl (management) interface is also used to manage triggered POIs, such as located in the UPF 490. The triggered POI may report CC to the MDF3 352 when packets come. Besides the SMF and the UPF, the POIs may also be located in other network functions such as unified data management (UDM).

[0110] It should be noted that the SMF 480 and the UPF 490 are merely exemplary examples of the components in the communication system and may be replaced by components with similar functionalities. For example, in a case where portions of the architecture of FIG. 3 are mapped to certain network nodes of an evolved packet core (EPC), and thus, a target of lawful interception is served by the EPC, the SMF may be replaced by a packet data network gateway control plane (PGW-C), and the UPF may be replaced by a packet data network gateway user plane (PGW-U). Therefore, the specific terms used herein do not limit the present disclosure only to the communication system related to the specific terms, which however can be more generally applied to other communication systems.

[0111] It should also be noted that the principle of the present disclosure is not only applicable to 3GPP and ETSI defined 4G and 5G lawful intercept support, but also applicable to any other architecture or system for private lawful intercept, as long as thesame requirement of “stopping interception when the target is roaming outbound internationally” is needed.

[0112] Within the context of this disclosure, the term UE or terminal device may also be referred to as, for example, device, access terminal, mobile station, mobile unit, subscriber station, or the like. It may refer to any end device that can access a wireless communication network and receive services therefrom. By way of example and not limitation, the UE or terminal device may include a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and playback appliance, a mobile phone, a cellular phone, a smart phone, a tablet, a wearable device, a personal digital assistant (PDA), or the like.

[0113] In an Internet of things (loT) scenario, a UE or terminal device may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE or terminal device and / or a network equipment. In this case, the UE or terminal device may be a machine-to-machine (M2M) device, which may, in a 3GPP context, be referred to as a machine-type communication (MTC) device. Particular examples of such machines or devices may include sensors, metering devices such as power meters, industrial machineries, bikes, vehicles, or home or personal appliances, e.g. refrigerators, televisions, personal wearables such as watches, and so on.

[0114] As used herein, the term “communication system” refers to a system following any suitable communication standards, such as the first generation (1G), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G, 5G communication protocols, and / or any other protocols either currently known or to be developed in the future. Furthermore, the communications between a terminal device and a network entity (or a network function) in the communication system may be performed according to any suitable generation communication protocols, including, but not limited to, 1G, 2G, 2.5G, 2.75G, 3G, 4G, 4.5G, 5G communication protocols, and / or any other protocols either currently known or to be developed in the future. The network node (or network function) in the communication system may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[0115] FIGs. 5A-5C are flowcharts each illustrating a process according to an embodiment of the disclosure. As shown, the process of each of FIGs. 5A-5C involves five entities: a V-SMF, a first network node implementing session management, a user plane node, an MDF, and an LEMF. The process relates to a scenario where a PDU session is established for a target of lawful interception when the target is in non-roaming state in a home network, and then the target moves out internationally from the home network to a visiting network. The target may refer to a subscriber / user and / or a UE / terminal device involved in the interception. The V-SMF is the SMF serving the target in the visiting network. Although a 5G core network function (SMF) is used here, it should be noted that the principle of the present disclosure may also be applicable to EPC network element. The first network node may be an SMF, a PGW-C, or any other network node (or network function) having similar functionality. The user plane node may be a UPF, a PGW-U, or any other network node (or network function) having similar functionality. The MDF may be MDF2. Note that only those blocks relevant to the present disclosure are shown in FIGs. 5A-5C and some blocks may be omitted so as not to obscure the principle of the present disclosure.

[0116] In the process of FIG. 5A, at block 501, the V-SMF sends, to the first network node, a create request for creating a new PDU session or creating an association with an existing packet data network (PDN) connection for the target. At block 502, the first network node determines whether or not the target has roamed out internationally from the home network to the visiting network. This may be done by determining whether a mobile country code (MCC) in a permanent identifier of a subscriber (e.g. subscription permanent identifier (SUPI) or international mobile subscriber identity (IMSI)) associated with the target is different from an MCC of a serving network of the target and another network node implementing session management is inserted in the visiting network of the target. The permanent identifier of the subscriber and the MCC of the serving network may be obtained from the received create request so as to perform comparison. The insertion of the another network node may be determined from an ID of the V-SMF contained in the create request. Since the process assumes that the target moves out internationally to the visiting network, the determination result at block 502 is positive.

[0117] At block 503, the first network node sends, to the user plane node, a fifth message for deactivating an interception for the target in response to determining that the target has roamed out internationally. For example, the fifth message may be an LI T3 Deactivate Task message. At block 504, the user plane node stops the LI reporting for the target according to the received fifth message. In this way, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for MDF3 to avoid hanging session.

[0118] At block 505, the first network node sends, to the MDF, a first message indicating that a PDU session has been modified for the target. The first message comprises a first indicator indicating that the target has roamed out. For example, the first message may be an LI X2 IRI message containing a record about PDU session modification. The first indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the first value is used in this case. Note that the first indicator may take any other suitable form.

[0119] At block 506, the MDF clears the corresponding interception session for the target. As an example, the corresponding interception session may be cleared as soon as the first message is received. As another example, the corresponding interception session may be cleared after a predetermined time period has elapsed since the first message is received. For instance, a timer may be started when the first message is received and the corresponding interception session may be cleared when the timer expires. In this way, because of the newly introduced first indicator, hanging session in the MDF can be avoided. Note that similar mechanism may be used in MDF3 to clear the corresponding interception session.

[0120] At block 512, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally. For example, the report message may be an LI HI2 IRI message having an IRI type set to END. In this way, the change related to the interception can be notified to the LEMF.

[0121] With the above process of FIG. 5 A, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the MDF2 and MDF3 to avoid hanging session.

[0122] Blocks 501-504 of FIG. 5B is same as those of FIG. 5A and their detailed description is omitted here for brevity. At block 507, the first network node sends, to the MDF, a second message indicating that an interception is stopped for the target. For example, the second message may be a new LI X2 IRI message containing a record about stop of interception. The second message may comprise a second indicator indicating that a cause of stopping of the interception is roaming out of the target. The second indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target, so that the first value is used in this case. Note that the second indicator may take any other suitable form.

[0123] The second message may also comprise one or more of: a permanent identifier of a subscriber (e.g. SUPI) associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device (e.g. permanent equipment identifier (PEI)) associated with the PDU session involved in the interception; a generic public identifier of the subscriber (e.g. generic public subscription identifier (GPSI)) associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a PDN connection involved in the interception.

[0124] The details about the PDN connection may comprise one or more of: evolved packet system (EPS) subscriber identities associated with the PDN connection; a fourth indicator indicating whether an IMSI in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection.

[0125] At block 508, the MDF clears the corresponding interception session for the target. Since the “stop of interception” event is notified, the corresponding interception session may be cleared as soon as the second message is received. In this way, because of the newly introduced second message, hanging session in the MDF can be avoided. At block 512, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally. With the process of FIG. 5B, the same effect as the process of FIG. 5 A can be achieved.

[0126] Blocks 501-504 of FIG. 5C is same as those of FIG. 5A and their detailed description is omitted here for brevity. At block 509, the first network node sends, to theMDF, a third message indicating that a PDU session has been modified for the target. At block 510, the first network node sends, to the MDF, a fourth message indicating that the PDU session has been released for the target. The fourth message is sent after the third message. Accordingly, at block 511, the MDF clears the corresponding interception session for the target according to the received fourth message. At block 512, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally. With the process of FIG. 5C, the same effect as the process of FIG. 5A can be achieved.

[0127] FIGs. 6A-6C are flowcharts each illustrating a process according to an embodiment of the disclosure. The process of each of FIGs. 6A-6C involves five entities: an AMF, a first network node implementing session management, a user plane node, an MDF, and an LEMF. The process relates to a scenario where a PDU session is established for a target of lawful interception when the target is in HR roaming state, and then the target moves back from a visiting network in another country to the home network. The target may refer to a subscriber / user and / or a UE / terminal device involved in the interception. The AMF refers to the AMF serving the target in the home network. Although a 5G core network function (AMF) is used here, it should be noted that the principle of the present disclosure may also be applicable to EPC network element. The first network node may be an SMF, a PGW-C, or any other network node (or network function) having similar functionality. The user plane node may be a UPF, a PGW-U, or any other network node (or network function) having similar functionality. The MDF may be MDF2. Note that only those blocks relevant to the present disclosure are shown in FIGs. 6A-6C and some blocks may be omitted so as not to obscure the principle of the present disclosure.

[0128] At block 601, the AMF sends, to the first network node, a create request for creating a session management (SM) context to support a PDU session for the target. At block 602, the first network node determines whether or not the target has roamed back from the visiting network to the home network. This may be done by determining whether an MCC in a permanent identifier of a subscriber (e.g. SUPI or IMSI) associated with the target is same as an MCC of the serving network of the target and another network node implementing session management is removed from the visiting network. The permanent identifier of the subscriber and the MCC of the serving network may be obtained from thereceived create request so as to perform comparison. For example, if smfUri IE and hSmfUri IE are not contained in the create request received from the AMF, the first network node may determine that the another network node is removed. The term URI refers to uniform resource identifier. Since the process assumes that the target moves back to the home network, the determination result at block 602 is positive.

[0129] At block 603, the first network node sends, to the user plane node, a tenth message for activating an interception for the target in response to determining that the target has roamed back to the home network. For example, the tenth message may be an LI T3 Activate Task message. At block 604, the user plane node starts the LI reporting for the target according to the received tenth message. In this way, a solution can be provided to achieve LI service scoping for international roaming.

[0130] At block 605, the first network node sends, to the MDF, a sixth message indicating that a PDU session has been modified for the target. The sixth message comprises a fifth indicator indicating that the target has roamed back. For example, the sixth message may be an LI X2 IRI message containing a record about PDU session modification. The fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the second value is used in this case. Note that the fifth indicator may take any other suitable form.

[0131] At block 606, the MDF creates the corresponding interception session for the target if the interception session has not been created. In this way, because of the newly introduced fifth indicator, unidentifiable PDU session modification or release IRI events in the MDF can be avoided.

[0132] At block 612, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is started in response to the target having roamed back to the home network. For example, the report message may be an LI HI2 IRI message having an IRI type set to BEGIN. In this way, the change related to the interception can be notified to the LEMF.

[0133] With the above process of FIG. 6A, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the MDF2 to avoid unidentifiable PDU session modification or release IRI events.

[0134] Blocks 601-604 of FIG. 6B is same as those of FIG. 6A and their detailed description is omitted here for brevity. At block 607, the first network node sends, to the MDF, a seventh message indicating that an interception is started for the target. The seventh message comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target. For example, the seventh message may be an LI X2 IRI message containing a record about start of interception. The sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target, so that the second value is used in this case. Note that the sixth indicator may take any other suitable form.

[0135] At block 608, the MDF creates the corresponding interception session for the target if the interception session has not been created. In this way, because of the newly introduced sixth indicator, unidentifiable PDU session modification or release IRI events in the MDF can be avoided. At block 612, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is started in response to the target having roamed back to the home network. With the process of FIG. 6B, the same effect as the process of FIG. 6A can be achieved.

[0136] Blocks 601-604 of FIG. 6C is same as those of FIG. 6 A and their detailed description is omitted here for brevity. At block 609, the first network node sends, to the MDF, an eighth message indicating that a PDU session has been established for the target. At block 610, the first network node sends, to the MDF, a ninth message indicating that the PDU session has been modified for the target. The ninth message is sent after the eighth message. Accordingly, at block 611, the MDF creates the corresponding interception session for the target if the interception session has not been created. At block 612, the MDF sends, to the LEMF, a report message indicating that the LI reporting for the target is started in response to the target having roamed back to the home network. With the process of FIG. 6C, the same effect as the process of FIG. 6A can be achieved.

[0137] FIG. 7 is a flowchart illustrating a method performed by a first network node implementing session management according to an embodiment of the disclosure. The first network node may be an SMF, a PGW-C, or any other network node (or network function) having similar functionality. At block 702, the first network node determines whether or not a target has roamed out internationally from a home network to a visiting network, orwhether or not a target has roamed back from a visiting network to a home network. The target may refer to a subscriber / user and / or a UE / terminal device involved in the interception. For example, the determination of whether or not the target has roamed out internationally may be done by determining whether an MCC in a permanent identifier of a subscriber associated with the target is different from an MCC of a serving network of the target and another network node implementing session management is inserted in a visiting network of the target. If the two MCCs are different with each other and the another network node is inserted, the first network node may determine that the target has roamed out internationally. Further details about this determination have been described above with respect to block 502 of FIGs. 5A-5C.

[0138] The determination of whether or not the target has roamed back may be done by determining whether the MCC in the permanent identifier of the subscriber associated with the target is same as the MCC of the serving network of the target and another network node implementing session management is removed from the visiting network. If the two MCCs are same with each other and the another network node is removed, the first network node may determine that the target has roamed back. Further details about this determination have been described above with respect to block 602 of FIGs. 6A-6C.

[0139] At block 704, the first network node sends, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network. As a first option, the second network node may be an MDF (e.g. an MDF2). Sending one or more messages for stopping the LI reporting for the target may be implemented as block 806 of FIG. 8A, or block 808 of FIG. 8B, or block 810 of FIG. 8C. At block 806, the first network node sends a first message indicating that a PDU session has been modified for the target. The first message comprises a first indicator indicating that the target has roamed out. For example, the first message may be an LI X2 IRI message containing a record about PDU session modification. The first indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the first value is used in this case. With the newly introduced first indicator, it is possible to avoid hanging session in the MDF.

[0140] At block 808, the first network node sends a second message indicating that an interception is stopped for the target. For example, the second message may be a new LI X2 IRI message containing a record about stop of interception. The second message may comprise a second indicator indicating that a cause of stopping of the interception is roaming out of the target. The second indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target, so that the first value is used in this case. The second message may also comprise one or more of: a permanent identifier of a subscriber associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device associated with the PDU session involved in the interception; a generic public identifier of the subscriber associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a packet data network, PDN, connection involved in the interception. The details about the PDN connection may comprise one or more of: EPS subscriber identities associated with the PDN connection; a fourth indicator indicating whether an IMSI in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection. With the newly introduced second message, it is possible to avoid hanging session in the MDF.

[0141] At block 810, the first network node sends a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDU session has been released for the target. The fourth message is sent after the third message. For example, the third message may be an LI X2 IRI message containing a record about PDU session modification, and the fourth message may be an LI X2 IRI message containing a record about PDU session release. With the third and fourth messages being sent in this way, it is possible to avoid hanging session in the MDF.

[0142] As a second option, the second network node may be a user plane node. The user plane node may be a UPF, a PGW-U, or any other network node (or network function) having similar functionality. Sending one or more messages for stopping the LI reporting for the target may be implemented as block 912 of FIG. 9. At block 912, the first network node sends a fifth message for deactivating an interception for the target. For example, thefifth message may be an LI T3 Deactivate Task message. In this way, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for MDF3 to avoid hanging session.

[0143] In the above first option where the second network node is an MDF, sending one or more messages for starting the LI reporting for the target may be implemented as block 1014 of FIG. 10A, or block 1016 of FIG. 10B, or block 1018 of FIG. 10C. At block 10144, the first network node sends a sixth message indicating that a PDU session has been modified for the target. The sixth message comprises a fifth indicator indicating that the target has roamed back. For example, the sixth message may be an LI X2 IRI message containing a record about PDU session modification. The fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the second value is used in this case. With the newly introduced fifth indicator, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0144] At block 1016, the first network node sends a seventh message indicating that an interception is started for the target. The seventh message comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target. For example, the seventh message may be an LI X2 IRI message containing a record about start of interception. The sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target, so that the second value is used in this case. With the newly introduced sixth indicator, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0145] At block 1018, the first network node sends an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target. The ninth message is sent after the eighth message. For example, the eighth message may be an LI X2 IRI message containing a record about PDU session establishment, and the ninth message may be an LI X2 IRI message containing a record about PDU session modification. With the eighth and ninth messages being sent in this way, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0146] In the above second option where the second network node is a user plane node, sending one or more messages for starting the LI reporting for the target may be implemented as block 1120 of FIG. 11. At block 1120, the first network node sends a tenth message for activating an interception for the target. For example, the tenth message may be an LI T3 Activate Task message. In this way, a solution can be provided to achieve LI service scoping for international roaming.

[0147] With the method of FIG. 7, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the second network node to avoid problems such as hanging session and unidentifiable PDU session modification or release IRI events.

[0148] FIG. 12 is a flowchart illustrating a method performed by an MDF according to an embodiment of the disclosure. At block 1202, the MDF receives, from a first network node implementing session management, one or more messages for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The first network node may be an SMF, a PGW-C, or any other network node (or network function) having similar functionality. For example, receiving one or more messages for stopping the LI reporting for the target may be implemented as block 1306 of FIG. 13A, or block 1308 of FIG. 13B, or block 1310 of FIG. 13C. At block 1306, the MDF receives a first message indicating that a PDU session has been modified for the target. The first message comprises a first indicator indicating that the target has roamed out. For example, the first message may be an LI X2 IRI message containing a record about PDU session modification. The first indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the first value is used in this case. With the newly introduced first indicator, it is possible to avoid hanging session in the MDF.

[0149] At block 1308, the MDF receives a second message indicating that an interception is stopped for the target. For example, the second message may be a new LI X2 IRI message containing a record about stop of interception. The second message may comprise a second indicator indicating that a cause of stopping of the interception is roaming out of the target. The second indicator can have a first value indicating that the cause is roamingout of the target, and a second value indicating that the cause is roaming back of the target, so that the first value is used in this case. The second message may also comprise one or more of: a permanent identifier of a subscriber associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device associated with the PDU session involved in the interception; a generic public identifier of the subscriber associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a packet data network, PDN, connection involved in the interception. The details about the PDN connection may comprise one or more of: EPS subscriber identities associated with the PDN connection; a fourth indicator indicating whether an IMSI in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection. With the newly introduced second message, it is possible to avoid hanging session in the MDF.

[0150] At block 1310, the MDF receives a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDU session has been released for the target. The fourth message is received after the third message. For example, the third message may be an LI X2 IRI message containing a record about PDU session modification, and the fourth message may be an LI X2 IRI message containing a record about PDU session release. With the third and fourth messages being received in this way, it is possible to avoid hanging session in the MDF.

[0151] For example, receiving one or more messages for starting the LI reporting for the target may be implemented as block 1414 of FIG. 14A, or block 1416 of FIG. 14B, or block 1418 of FIG. 14C. At block 1414, the MDF receives a sixth message indicating that a PDU session has been modified for the target. The sixth message comprises a fifth indicator indicating that the target has roamed back. For example, the sixth message may be an LI X2 IRI message containing a record about PDU session modification. The fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back, so that the second value is used in this case. With the newly introduced fifth indicator, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0152] At block 1416, the MDF receives a seventh message indicating that an interception is started for the target. The seventh message comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target. For example, the seventh message may be an LI X2 IRI message containing a record about start of interception. The sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target, so that the second value is used in this case. With the newly introduced sixth indicator, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0153] At block 1418, the MDF receives an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target. The ninth message is received after the eighth message. For example, the eighth message may be an LI X2 IRI message containing a record about PDU session establishment, and the ninth message may be an LI X2 IRI message containing a record about PDU session modification. With the eighth and ninth messages being received in this way, it is possible to avoid unidentifiable PDU session modification or release IRI events in the MDF.

[0154] Referring back to FIG. 7, at block 1204, the MDF sends, to an LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network. For example, the report message indicating that the LI reporting for the target is stopped may be an IRI message having an IRI type set to END. The report message indicating that the LI reporting for the target is started may be an IRI message having an IRI type set to BEGIN. In this way, the change related to the interception can be notified to the LEMF.

[0155] With the method of FIG. 12, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for the MDF to avoid problems such as hanging session and unidentifiable PDU session modification or release IRI events.

[0156] FIG. 15 is a flowchart illustrating a method performed by a user plane node according to an embodiment of the disclosure. The user plane node may be a UPF, a PGW- U, or any other network node (or network function) having similar functionality. At block1502, the user plane node receives, from a first network node implementing session management, a message for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The first network node may be an SMF, a PGW-C, or any other network node (or network function) having similar functionality. The message for stopping the LI reporting for the target may be a fifth message for deactivating an interception for the target. For example, the fifth message may be an LI T3 Deactivate Task message. The message for starting the LI reporting for the target may be a tenth message for activating an interception for the target. For example, the tenth message may be an LI T3 Activate Task message.

[0157] At block 1504, the user plane node stops or starts the LI reporting for the target according to the received message. With the method of FIG. 15, a solution can be provided to achieve LI service scoping for international roaming so that it is possible for MDF3 to avoid problems such as hanging session.

[0158] FIG. 16 is a flowchart illustrating a method performed by an LEMF according to an embodiment of the disclosure. At block 1602, the LEMF receives, from an MDF, a report message indicating that LI reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network. For example, the report message indicating that the LI reporting for the target is stopped may be an IRI message having an IRI type set to END. The report message indicating that the LI reporting for the target is started may be an IRI message having an IRI type set to BEGIN. With the method of FIG. 16, a solution can be provided to achieve LI service scoping for international roaming.

[0159] FIGs. 17A and 17B are flowcharts illustrating an exemplary process according to an embodiment of the disclosure. The process relates to user roaming out case. The signaling flow shown in FIGs. 17A and 17B takes SMF as example for NF node. The precondition of the process is that H-SMF and V-SMF has received destination and provisioned tasks by ADMF. At step 1, the AMF sends Nsmf_PDUSession_ CreateSMContext Request message to the SMF. The request creates an individual sessionmanagement context for a given PDU. At step 2, the SMF sends Nsmf_ PDUSession_CreateSMContext Response message to the AMF. At step 3, the SMF sends Namf Communication EBIAssignment Request to the AMF for EBI. The AMF sends Response message to the SMF, containing the assigned EBI or EBIs. At step 4, the SMF sends the PFCP Session Establishment Request message to the UPF to allocate the CN tunnel. The UPF sends Response message to the SMF. At step 5, the SMF sends LI_T3 activateTask Request to the UPF to trigger UPF interception for provisioned tasks. At step 6, the SMF sends Namf_Communication_NlN2MessageTransfer Request message to the AMF, including N1 PDU Session Establishment Accept and N2 PDU Session Resource Setup Request Transfer messages. At step 7, the SMF reports LI_X2 PDU session establishment to the MDF2. At step 8, the MDF2 receives xIRI from the SMF via LI X2, then sends IRI message with type BEGIN to the LEMF. At step 9, the AMF responds with the Namf_Communication_N !N2MessageTransfer Response message to the SMF. At step 10, the AMF sends the Nsmf_PDUSession_ UpdateSMContext Request message to the SMF with N2 PDU Session Resource Setup Response Transfer message. At step 11, the SMF sends PFCP Session Modification Request message to the UPF to update the F-TEID of the RAN. The UPF sends the PFCP Session Modification Response message to the SMF. At step 12, the SMF sends LI_T3 to the UPF. At step 13, the SMF responds with Nsmf_PDUSession_UpdateSMContext Response message to the AMF. At step 14, the SMF reports LI_X2 PDU session modification to the MDF2 after update. At step 15, the MDF2 sends IRI message with type CONTINUE to the LEMF.

[0160] At step 16, when user is roaming out to other country, the V-SMF sends Nsmf PDUSession Create Request to the H-SMF. At step 17, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends Response message to the H- SMF. At step 18, the H-SMF sends LI T3 deactivateTask to the H-UPF to trigger the H- UPF to stop interception. At step 19, the H-SMF sends Nsmf_PDUSession_Create Response to the V-SMF. At step 20, the V-SMF sends Nsmf_PDUSession_Update Request with upCnxState Activated to the H-SMF. The H-SMF sends Response to the V- SMF.

[0161] At step 21, the H-SMF reports LI_X2 IRI event to notify the MDF2 session modification and indicate that interception will be stopped due to user roaming out. Theremay be 3 options for step 21. Option 1 is to reuse PDU session modification. The H-SMF sends LI X2 PDU session modification with new information element (IE) roamerState with value 0: OUT BOUND. Table 1 below shows an exemplary example of the roamerState IE.Table 1: EnumerationRoamerStateThis IRI PDU Session Modification event shall exclude user sensitive information such as location and serving network related IE. When the MDF2 receives this event, it shall parse the new IE and get task has been roaming out and no reporting afterwards until user roaming back.

[0162] Option 2 is to introduce a new event StopOflnterception. The H-SMF sends new LI X2 IRI event StopOflnterception defined in Table 2 below.Table 2: Payload for StopOflnterception record

[0163] The payload for ePSStopOflnterceptionWithPDNConnection field is defined in Table 3 below.Table 3: Payload for ePSStopOflnterceptionWithPDNConnection field

[0164] In Table 2, a new IE cause with value 0 roaming out indicates the reason of NF stop interception. It can be extensible for further possible scenarios. When the MDF2 receives this event, it shall parse the new event and get that one specific task has been roaming out and no reporting afterwards until user roaming back.

[0165] Option 3 is to report PDU session modification together with PDU session release. The H-SMF sends LI X2 IRI PDU session modification and PDU session release to the MDF2. No specific IE is added. PDU session release is used for the MDF2 to not keep the session of this task since the task has been stopped. It helps avoid hanging session in MDF2 and MDF3 although release event is not exact.

[0166] At step 22, after receiving xIRI from the H-SMF via LI_X2 interface, the MDF2 sends IRI message END to the LEMF. At step 23, the H-SMF sends PFCP session modification to the H-UPF. The H-UPF sends Response message to the H-SMF.

[0167] At steps 24-28, the UE triggers PDU session release in HR-Roaming cases. The H-SMF will not report any LI X2 IRI events. No LI T3 request is sent to the H-UPF either.

[0168] FIGs. 18A and 18B are flowcharts illustrating an exemplary process according to an embodiment of the disclosure. The process relates to user roaming back case. Thesignaling flow shown in FIGs. 18A and 18B takes SMF as example for NF node. At steps 1-5, PDU session is established with international HR Roaming. The H-SMF does not report any LI X2 message to the MDF2. Similarly, the H-UPF does not report LI X3 CC.

[0169] At step 6, the UE moves from VPLMN to HPLMN, and V-SMF will be removed. The AMF sends Nsmf_PDUSession_CreateSMContext Request to the H-SMF. At step 7, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends response to the H-SMF. At step 8, the H-SMF sends Nsmf_PDUSession_ CreateSMContext Response to the AMF. At step 9, the AMF sends Nsmf_PDUSession_ UpdateSMContext Request to the H-SMF. At step 10, the H-SMF sends PFCP session modification request to the H-UPF. The H-UPF sends response to the H-SMF. At step 11, the H-SMF sends LI T3 activateTask to the H-UPF to trigger H-UPF interception. At step 12, the H-SMF sends Nsmf_PDUSession_UpdateSMContext Response to the AMF.

[0170] At step 13, the H-SMF sends LI X2 IRI event to the MDF2 to indicate start of interception due to roaming back. There may be 3 options for step 13. Option 1 is to use PDU session modification. The H-SMF sends LI X2 PDU session modification with new IE roamerState with value 1: BACK TO HOME. Table 4 below shows an exemplary example of the roamerState IE.Table 4: Enumeration RoamerStateWhen the MDF2 receives this event, it shall parse the new IE and get task has been roaming back to HPLMN and start interception afterwards.

[0171] Option 2 is to reuse StartOflnterception. The H-SMF sends LI X2 IRI event StartOflnterception with new IE cause to indicate user roaming back to HPLMN. Table 5 below shows payload for SMFStartOflnterceptionWithEstablishedPDUSession record from Table 6.2.3-4 of TS 33.128 V18.7.0, where the new added IE is highlighted with underlines.Table 5: Payload for SMFStartOflnterceptionWithEstablishedPDUSession recordThe new IE cause indicates the reason of NF start interception. Roaming back to home is a new condition for start of interception. It can be extensible for further possible scenarios. When the MDF2 receives this event, it shall parse the new IE and get that one specific task has been roaming back and start reporting afterwards.

[0172] Option 3 is to use PDU session establishment together with PDU session modification. The H-SMF sends LI X2 IRI PDU session establishment and PDU session modification to the MDF2. No specific IE is added. PDU session establishment is used for the MDF2 to create session of this task to avoid that MDF2 and MDF3 cannot identify the PDU session modification event without establishment.

[0173] At step 14, after receiving xIRI from the H-SMF, the MDF2 sends IRI message BEGIN to the LEMF. At step 15, the H-SMF sends PFCP session modification request to the H-UPF if policy and charging control (PCC) updates. The H-UPF sends response to the H-SMF.

[0174] At step 16, the AMF sends Nsmf_PDUSession_UpdateSMContext Request to the SMF to release PDU session. At step 17, the SMF sends PFCP session delete request to the UPF. The UPF sends response to the SMF. At step 18, the SMF sends LI T3 deactiveTask request to the UPF. The UPF sends response to the SMF. At step 19, the SMF sends Nsmf_PDUSession_UpdateSMContext Response to the AMF. At step 20, the AMF sends Nsmf_PDUSession_UpdateSMContext Request with N2 info to the SMF. The SMF sends response to the AMF. At step 21, the AMF sends Nsmf_PDUSession_ UpdateSMContext Request with N1 info to the SMF. The SMF sends response to the AMF. At step 22, the SMF sends Nsmf_PDUSession_SMContextStatusNotify Request with resource status being released to the AMF. At step 23, the AMF replies with Nsmf_PDUSession_SMContextStatusNotify Response to the SMF. At step 24, the SMFreports LI_X2 PDU session release to the MDF2. At step 25, based on the received report from the SMF, the MDF2 sends IRI END to the LEMF.

[0175] Based on the above description, three options are proposed to help the H-SMF stop interception of outbound international roamer and restart interception of inbound roamer by updating LI X2 messages. The options mainly focus on LI X2 and LI T3 interface.

[0176] As the first option, when international roamer is roaming out to VPLMN, that is V-SMF is inserted, H-SMF decides user is roaming out by comparing MCC in SUPI and MCC in serving network. The H-SMF sends to MDF2 IRI event PDU Session Modification with new IE roamerState with value OUT BOUND to specify outbound roamer, so that servingNetwork together with location which contains sensitive user information shall be excluded for reporting. This is a suspend signal for MDF2 that there will be no IRI events and CC to be reported from the H-SMF until user roams back to HPLMN. This is also a suspend signal for MDF3 since MDF2 can indicate suspension of interception to MDF3.

[0177] Based on this specific PDU Session Modification event, MDF2 and MDF3 in HPLMN can decide to clear all related outbound roaming session, or to keep the session to wait for user roaming back to HPLMN. If MDF2 and MDF3 decide to keep the session, there should be internal clear mechanism (e.g. a timer) in MDFx to delete session because the session may be released in VPLMN.

[0178] In addition, MDF2 sends SMFPDUSessionModification record to LEMF, but the IRI type shall be mapped to END.

[0179] When international roamer is roaming back to HPLMN, that is V-SMF is removed, the H-SMF decides user is roaming back, then the H-SMF needs to resume interception by sending LI X2 PDU Session Modification with new IE roamerState with value BACK TO HOME to specify that the user is roaming back and becomes nonroaming user.

[0180] For MDF2, when receiving PDU Session Modification with roamerState BACK TO HOME, if the session is not created due to no PDU session establishmentbeing received before or the session being cleared before due to user roaming out, MDF2 shall create the session accordingly just as PDU session establishment.

[0181] In addition, MDF2 sends SMFPDUSessionModification record to LEMF, but the IRI type shall be mapped to BEGIN.

[0182] As the second option, when international roamer is roaming out to VPLMN, that is V-SMF is inserted, H-SMF decides user is roaming out by comparing MCC in SUPI and MCC in serving network. The H-SMF sends to MDF2 new IRI stopOflnterception to specify outbound roamer. For MDF2 and MDF3, there will be no IRI events and CC to be reported from the H-SMF. MDF2 and MDF3 in HPLMN shall clear all related outbound roaming session based on this specific stopOflnterception event.

[0183] MDF2 sends SMFStopOflnterception record to LEMF, and the IRI type shall be mapped to END.

[0184] When international roamer is roaming back to HPLMN, that is V-SMF is removed, the H-SMF decides user is roaming back, then the H-SMF needs to restart interception by sending LI X2 StartOflnterception to specify user roaming back to become non-roaming user.

[0185] For MDF2, this StartOflntereption handling is same as current function, but a new trigger user international roaming back is introduced. Then MDF2 sends SMFStartOflnterceptionWithEstablishedPDUSession record to LEMF, and the IRI type shall be mapped to BEGIN.

[0186] As the third option, when international roamer is roaming out to VPLMN, that is V-SMF is inserted, H-SMF decides user is roaming out by comparing MCC in SUPI and MCC in serving network. The H-SMF sends MDF2 PDU Session Modification to specify user roaming out internationally. Besides, H-SMF will send extra PDU Session release to indicate MDF2 and MDF3 that interception will be stopped and avoid hanging session. In this PDU session modification and release event, the sensitive user information such as location and serving network, shall not be reported to MDF2.

[0187] MDF2 sends SMFPDUSessionModification record with IRI type CONTINUE to LEMF, and then send SMFPDUSessionRelease with the IRI type END to LEMF.

[0188] When international roamer is roaming back to HPLMN, that is V-SMF is removed, the H-SMF decides user is roaming back to become non-roaming user, then the H-SMF needs to restart interception by sending LI X2 PDU Session Modification and extra PDU session establishment event. The PDU session establishment shall be reported before PDU session modification event.

[0189] For MDF2, the PDU establishment helps to create session when user is roaming back. MDF2 sends SMFPDUSessionEstablishment record to LEMF, and the IRI type shall be mapped to BEGIN. Then another SMFPDUSessionModification record with IRI type CONTINUE shall be sent to LEMF.

[0190] Even though the extra PDU session release and PDU session establishment are not correct (or accurate), they help MDF2 and MDF3 solve the potential problem, while no new requirement on MDF2 and MDF3 are needed.

[0191] With any of the above three options, it can help MDF2 and MDF3 get the roaming information and correctly handle the interception session, so as to avoid e.g. hanging session and unidentifiable session.

[0192] FIG. 19 is a flowchart illustrating an exemplary process according to an embodiment of the disclosure. The precondition of the process is that the destination and tasks have been provisioned in NF by ADMF. The process takes SMF as example for NF node. At step 1901, the SMF receives a request for a new procedure. Then, at step 1902, the SMF compares MCC in SUPI and MCC in serving network. If they are different, the international roaming happens. If V-SMF is inserted, the SMF changes mode from normal SMF to H-SMF at step 1903. Then, the H-SMF shall stop reporting LI X2 events and send deactivateTask request to trigger H-UPF stop interception at step 1903. If V-SMF is removed, the SMF changes mode from H-SMF to normal SMF. Then, the SMF shall restart interception and send activateTask request to trigger H-UPF interception at step 1904.

[0193] On the other hand, if there is no change in the SMF role, the SMF determines whether the SMF role is H-SMF at step 1905. If the SMF role is H-SMF, LI X2 and LI X3 keep no reporting at step 1906. If the SMF role is not H-SMF, LI X2 and LI X3 reporting is performed for interception at step 1907.

[0194] FIG. 20 is a block diagram illustrating an apparatus suitable for use in practicing some embodiments of the disclosure. For example, any one of the first network node, the MDF, the user plane node and the LEMF described above may be implemented through the apparatus 2000. As shown, the apparatus 2000 may include a processor 2010, a memory 2020 that stores a program, and optionally a communication interface 2030 for communicating data with other external devices through wired and / or wireless communication.

[0195] The program includes program instructions that, when executed by the processor 2010, enable the apparatus 2000 to operate in accordance with the embodiments of the present disclosure, as discussed above. That is, the embodiments of the present disclosure may be implemented at least in part by computer software executable by the processor 2010, or by hardware, or by a combination of software and hardware.

[0196] The memory 2020 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memories, magnetic memory devices and systems, optical memory devices and systems, fixed memories and removable memories. The processor 2010 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architectures, as non-limiting examples.

[0197] Based on the above description, the present disclosure also provides a computer program product. The computer program product may comprise instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of the above method embodiments.

[0198] In addition, the present disclosure also provides a computer readable storage medium. The computer readable storage medium may store thereon instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of the above method embodiments.

[0199] FIG. 21 is a block diagram illustrating a first network node implementing session management according to an embodiment of the disclosure. As shown in FIG. 21, the firstnetwork node 2100 may comprise a determination module 2102 and a sending module 2104. The determination module 2102 may be configured to determine whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network. The sending module 2104 may be configured to send, to a second network node, one or more messages for stopping LI reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

[0200] FIG. 22 is a block diagram illustrating an MDF according to an embodiment of the disclosure. As shown in FIG. 22, the MDF 2200 may comprise a reception module 2202 and a sending module 2204. The reception module 2202 may be configured to receive, from a first network node implementing session management, one or more messages for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The sending module 2204 may be configured to send, to an LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

[0201] FIG. 23 is a block diagram illustrating a user plane node according to an embodiment of the disclosure. As shown in FIG. 23, the user plane node 2300 may comprise a reception module 2302 and a control module 2304. The reception module 2302 may be configured to receive, from a first network node implementing session management, a message for stopping LI reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network. The control module 2304 may be configured to stop or start the LI reporting for the target according to the received message.

[0202] FIG. 24 is a block diagram illustrating an LEMF according to an embodiment of the disclosure. As shown in FIG. 24, the LEMF 2400 may comprise a reception module 2402. The reception module 2402 may be configured to receive, from an MDF, a reportmessage indicating that LI reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network. The modules described above may be implemented by hardware, or software, or a combination of both.

[0203] As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

[0204] It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, RAM, etc. As will be appreciated by one skilled in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

[0205] References in the present disclosure to “one embodiment”, “an embodiment” and so on, indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledgeof one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0206] It should be understood that, although the terms “first”, “second” and so on may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of the disclosure. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed terms.

[0207] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. The terms “connect”, “connects”, “connecting” and / or “connected” used herein cover the direct and / or indirect connection between two elements. It should be noted that two blocks shown in succession in the above figures may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0208] The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-Limiting and exemplary embodiments of this disclosure.

Claims

Claims1. A method at a first network node implementing session management, the method comprising: determining (702) whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network; and sending (704), to a second network node, one or more messages for stopping lawful interception, LI, reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

2. The method according to claim 1, wherein the second network node comprises a mediation and delivery function, MDF; and wherein sending (704) one or more messages for stopping the LI reporting for the target comprises one of: sending (806) a first message indicating that a protocol data unit, PDU, session has been modified for the target, wherein the first message comprises a first indicator indicating that the target has roamed out; sending (808) a second message indicating that an interception is stopped for the target; and sending (810) a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDU session has been released for the target, wherein the fourth message is sent after the third message.

3. The method according to claim 2, wherein the second message comprises a second indicator indicating that a cause of stopping of the interception is roaming out of the target.

4. The method according to claim 2 or 3, wherein the second message comprises one or more of:a permanent identifier of a subscriber associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device associated with the PDU session involved in the interception; a generic public identifier of the subscriber associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a packet data network, PDN, connection involved in the interception.

5. The method according to claim 4, wherein the details about the PDN connection comprises one or more of: evolved packet system, EPS, subscriber identities associated with the PDN connection; a fourth indicator indicating whether an international mobile subscriber identity, IMSI, in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection.

6. The method according to any of claims 2 to 5, wherein the first message is an LI X2 interception related information, IRI, message containing a record about PDU session modification; or wherein the second message is a new LI X2 IRI message containing a record about stop of interception; or wherein the third message is an LI X2 IRI message containing a record about PDU session modification, and the fourth message is an LI X2 IRI message containing a record about PDU session release.

7. The method according to claim 1, wherein the second network node comprises a user plane node; andwherein sending (704) one or more messages for stopping the LI reporting for the target comprises: sending (912) a fifth message for deactivating an interception for the target.

8. The method according to claim 7, wherein the fifth message is an LI T3 Deactivate Task message.

9. The method according to claim 1, wherein the second network node comprises a mediation and delivery function, MDF; and wherein sending (704) one or more messages for starting the LI reporting for the target comprises one of: sending (1014) a sixth message indicating that a PDU session has been modified for the target, wherein the sixth message comprises a fifth indicator indicating that the target has roamed back; sending (1016) a seventh message indicating that an interception is started for the target, wherein the seventh message comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target; and sending (1018) an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target, wherein the ninth message is sent after the eighth message.

10. The method according to claim 9, wherein the sixth message is an LI_X2 IRI message containing a record about PDU session modification; or wherein the seventh message is an LI X2 IRI message containing a record about start of interception; or wherein the eighth message is an LI X2 IRI message containing a record about PDU session establishment, and the ninth message is an LI X2 IRI message containing a record about PDU session modification.

11. The method according to claim 1, wherein the second network node comprises a user plane node; andwherein sending (704) one or more messages for starting the LI reporting for the target comprises: sending (1120) a tenth message for activating an interception for the target.

12. The method according to claim 11, wherein the tenth message is an LI T3 Activate Task message.

13. The method according to any of claims 2, 3 and 9, wherein the first or the fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back; and / or wherein the second or the sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target.

14. The method according to any of claims 1 to 13, wherein when a mobile country code, MCC, in a permanent identifier of a subscriber associated with the target is different from an MCC of a serving network of the target and another network node implementing session management is inserted in a visiting network of the target, it is determined that the target has roamed out internationally from the home network to the visiting network; or wherein when the MCC in the permanent identifier of the subscriber associated with the target is same as the MCC of the serving network of the target and the another network node implementing session management is removed from the visiting network, it is determined that the target has roamed back from the visiting network to the home network.

15. The method according to any of claims 1 to 14, wherein the first network node comprises one of: a session management function, SMF; and a packet data network gateway control plane, PGW-C.

16. The method according to any of claims 7, 8, 11 and 12, wherein the user plane node comprises one of: a user plane function, UPF; and a packet data network gateway user plane, PGW-U.

17. A method at a mediation and delivery function, MDF, the method comprising: receiving (1202), from a first network node implementing session management, one or more messages for stopping lawful interception, LI, reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network; and sending (1204), to a law enforcement monitoring facility, LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

18. The method according to claim 17, wherein receiving (1202) one or more messages for stopping the LI reporting for the target comprises one of: receiving (1306) a first message indicating that a protocol data unit, PDU, session has been modified for the target, wherein the first message comprises a first indicator indicating that the target has roamed out; receiving (1308) a second message indicating that an interception is stopped for the target; and receiving (1310) a third message indicating that a PDU session has been modified for the target, and a fourth message indicating that the PDU session has been released for the target, wherein the fourth message is received after the third message.

19. The method according to claim 18, wherein the second message comprises a second indicator indicating that a cause of stopping of the interception is roaming out of the target.

20. The method according to claim 18 or 19, wherein the second message comprises one or more of: a permanent identifier of a subscriber associated with a PDU session involved in the interception; a third indicator indicating whether a permanent identifier of the subscriber is unauthenticated; a permanent identifier of a terminal device associated with the PDU session involved in the interception; a generic public identifier of the subscriber associated with the PDU session involved in the interception; an identifier of the PDU session involved in the interception; and details about a packet data network, PDN, connection involved in the interception.

21. The method according to claim 20, wherein the details about the PDN connection comprises one or more of: evolved packet system, EPS, subscriber identities associated with the PDN connection; a fourth indicator indicating whether an international mobile subscriber identity, IMSI, in the EPS subscriber identities is unauthenticated; an EPS bearer identity of a default bearer associated with the PDN connection; and a list of bearer contexts associated with the PDN connection.

22. The method according to any of claims 18 to 21, wherein the first message is an LI X2 interception related information, IRI, message containing a record about PDU session modification; or wherein the second message is a new LI X2 IRI message containing a record about stop of interception; or wherein the third message is an LI X2 IRI message containing a record about PDU session modification, and the fourth message is an LI X2 IRI message containing a record about PDU session release.

23. The method according to claim 17, wherein receiving (1204) one or more messages for starting the LI reporting for the target comprises one of: receiving (1414) a sixth message indicating that a PDU session has been modified for the target, wherein the sixth message comprises a fifth indicator indicating that the target has roamed back; receiving (1416) a seventh message indicating that an interception is started for the target, wherein the seventh message comprises a sixth indicator indicating that a cause of starting of the interception is roaming back of the target; and receiving (1418) an eighth message indicating that a PDU session has been established for the target, and a ninth message indicating that the PDU session has been modified for the target, wherein the ninth message is received after the eighth message.

24. The method according to claim 23, wherein the sixth message is an LI_X2 IRI message containing a record about PDU session modification; or wherein the seventh message is an LI X2 IRI message containing a record about start of interception; or wherein the eighth message is an LI X2 IRI message containing a record about PDU session establishment, and the ninth message is an LI X2 IRI message containing a record about PDU session modification.

25. The method according to any of claims 18, 19 and 23, wherein the first or fifth indicator can have a first value indicating that the target has roamed out, and a second value indicating that the target has roamed back; and / or wherein the second or sixth indicator can have a first value indicating that the cause is roaming out of the target, and a second value indicating that the cause is roaming back of the target.

26. The method according to any of claims 17 to 25, wherein the report message indicating that the LI reporting for the target is stopped is an IRI message having an IRI type set to END; or wherein the report message indicating that the LI reporting for the target is started is an IRI message having an IRI type set to BEGIN.

27. The method according to any of claims 17 to 26, wherein the first network node implementing session management comprises one of: a session management function, SMF; and a packet data network gateway control plane, PGW-C.

28. A method at a user plane node, the method comprising: receiving (1502), from a first network node implementing session management, a message for stopping lawful interception, LI, reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network; and stopping or starting (1504) the LI reporting for the target according to the received message.

29. The method according to claim 28, wherein the message for stopping the LI reporting for the target comprises: a fifth message for deactivating an interception for the target.

30. The method according to claim 29, wherein the fifth message is an LI T3 Deactivate Task message.

31. The method according to claim 28, wherein the message for starting the LI reporting for the target comprises: a tenth message for activating an interception for the target.

32. The method according to claim 31, wherein the tenth message is an LI T3 Activate Task message.

33. The method according to any of claims 28 to 32, wherein the first network node comprises one of: a session management function, SMF; and a packet data network gateway control plane, PGW-C; and / orwherein the user plane node comprises one of: a user plane function, UPF; and a packet data network gateway user plane, PGW-U.

34. A method at a law enforcement monitoring facility, LEMF, the method comprising: receiving (1602), from a mediation and delivery function, MDF, a report message indicating that lawful interception, LI, reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network.

35. The method according to claim 34, wherein the report message indicating that the LI reporting for the target is stopped is an interception related information, IRI, message having an IRI type set to END; or wherein the report message indicating that the LI reporting for the target is started is an IRI message having an IRI type set to BEGIN.

36. A first network node (2000) implementing session management, the first network node comprising: at least one processor (2010); and at least one memory (2020), the at least one memory (2020) containing instructions executable by the at least one processor (2010), whereby the first network node (2000) is operative to: determine whether or not a target has roamed out internationally from a home network to a visiting network, or whether or not a target has roamed back from a visiting network to a home network; and send, to a second network node, one or more messages for stopping lawful interception, LI, reporting for the target in response to determining that the target has roamed out internationally, or starting the LI reporting for the target in response to determining that the target has roamed back to the home network.

37. The first network node (2000) according to claim 36, wherein the first network node (2000) is operative to perform the method according to any of claims 2 to 16.

38. A mediation and delivery function, MDF (2000), comprising: at least one processor (2010); and at least one memory (2020), the at least one memory (2020) containing instructions executable by the at least one processor (2010), whereby the MDF (2000) is operative to: receive, from a first network node implementing session management, one or more messages for stopping lawful interception, LI, reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network; and send, to a law enforcement monitoring facility, LEMF, a report message indicating that the LI reporting for the target is stopped in response to the target having roamed out internationally, or the LI reporting for the target is started in response to the target having roamed back to the home network.

39. The MDF (2000) according to claim 38, wherein the MDF (2000) is operative to perform the method according to any of claims 18 to 27.

40. A user plane node (2000) comprising: at least one processor (2010); and at least one memory (2020), the at least one memory (2020) containing instructions executable by the at least one processor (2010), whereby the user plane node (2000) is operative to: receive, from a first network node implementing session management, a message for stopping lawful interception, LI, reporting for a target in response to the target having roamed out internationally from a home network to a visiting network, or starting LI reporting for a target in response to the target having roamed back from a visiting network to a home network; and stop or start the LI reporting for the target according to the received message.

41. The user plane node (2000) according to claim 40, wherein the user plane node (2000) is operative to perform the method according to any of claims 29 to 33.

42. A law enforcement monitoring facility, LEMF (2000), comprising: at least one processor (2010); and at least one memory (2020), the at least one memory (2020) containing instructions executable by the at least one processor (2010), whereby the LEMF (2000) is operative to: receive, from a mediation and delivery function, MDF, a report message indicating that lawful interception, LI, reporting for a target is stopped in response to the target having roamed out internationally from a home network to a visiting network, or LI reporting for a target is started in response to the target having roamed back from a visiting network to a home network.

43. The LEMF (2000) according to claim 42, wherein the LEMF (2000) is operative to perform the method according to claim 35.

44. A computer readable storage medium storing thereon instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of claims 1 to 35.

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