WO2022232999A1

WO2022232999A1 - A method for session management function relocation

Info

Publication number: WO2022232999A1
Application number: PCT/CN2021/091945
Authority: WO
Inventors: Jinguo Zhu; Zhijun Li
Original assignee: Zte Corporation
Priority date: 2021-05-06
Filing date: 2021-05-06
Publication date: 2022-11-10
Also published as: CN117597978A

Abstract

A wireless communication method for use in a first session management function is disclosed. The method comprises receiving, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises first wireless terminal location information associated with a first wireless communication node, transmitting, to a second session management function, a session context request associated with the protocol data unit session, and receiving, from the second session management function, a session context associated with the protocol data unit session, wherein the session context comprises second wireless terminal location information associated with a second wireless network node.

Description

A Method for Session Management Function Relocation

This document is directed generally to wireless communications.

The intermediate session management function (I-SMF) of a user equipment (UE) may be relocated for different reasons. For example, the I-SMF may be relocated when the UE moves outside of the service area of the serving SMF/I-SMF, when the serving I-SMF is not suitable for the serving network slice, and/or when the serving I-SMF does not support the requested data network access identification (DNAI) . During the I-SMF relocation, certain information (e.g. channel configuration) may be available for being reused for reducing signal overhead. However, it is unclear what kind of information should be reused and when the information should be reused.

This document relates to methods, systems, and devices for an SMF relocation, and in particular to an I-SMF relocation.

The present disclosure relates to a wireless communication method for use in a first session management function. The method comprises:

receiving, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises first wireless terminal location information associated with a first wireless communication node,

transmitting, to a second session management function, a session context request associated with the protocol data unit session,

receiving, from the second session management function, a session context associated with the protocol data unit session, wherein the session context comprises second wireless terminal location information associated with a second wireless network node.

Various embodiments may preferably implement the following features:

Preferably, the first wireless terminal location information and the second wireless terminal location information are the same, the session context further comprises tunnel information associated with an interface between the second wireless network node and a first user plane function, and the method further comprises at least one of:

using the tunnel information for the protocol data unit session, or

transmitting, to a second user plane function, the tunnel information.

Preferably, the tunnel information comprises at least one of an internet protocol address or a tunnel endpoint identifier of the protocol data unit session in the second wireless communication node.

Preferably, the first wireless terminal location information and the second wireless terminal location information are the same, and the method further comprises transmitting, to the access and mobility management function, a request of modifying the session context associated with the protocol data unit session.

Preferably, the first wireless terminal location information and the second wireless terminal location information are different, and the method further comprises transmitting, to the access and mobility management function, a request of establishing the session context associated with the protocol data unit session.

Preferably, each of the first wireless terminal location information and the second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.

The present disclosure relates to a wireless communication method for use in a second session management function. The method comprises:

receiving, from a first session management function, a session context request associated with a protocol data unit session, and

transmitting, to the first session management function, a session context comprising second wireless terminal location information associated with a second wireless network node.

Various embodiments may preferably implement the following features:

Preferably, the wireless communication method further comprises receiving, from an access and mobility management function, the second wireless terminal location information.

Preferably, the second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.

Preferably, the session context further comprises tunnel information associated with an interface between the second wireless network node and a first user plane function.

Preferably, the wireless communication method further comprises receiving, from an access and mobility management function, the tunnel information.

The present disclosure relates to a wireless communication method for use in a first session management function. The method comprises receiving, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.

Various embodiments may preferably implement the following features:

Preferably, the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid, wherein the method further comprises:

transmitting, to a second session management function, a session context request associated with the protocol data unit session, wherein the session context request comprises an indication of requesting tunnel information associated with an interface between the second wireless network node and a first user plane function.

receiving, from a second session management function, a session context of the protocol data unit session, wherein the session context comprises tunnel information associated with an interface between the second wireless network node and a first user plane function, and

wherein the method further comprises at least one of:

using the tunnel information for the protocol data unit session, or

transmitting, to a second user plane function, the tunnel information.

Preferably, the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid, and the method further comprises:

transmitting, to the access and mobility management function, a request of modifying the session context associated with the protocol data unit session.

Preferably, the indication indicates that the session information in the second wireless network node of the protocol data unit session is not valid, and wherein the method further comprises:

transmitting, to the access and mobility management function, a request of establishing the session context associated with the protocol data unit session.

The present disclosure relates to a wireless communication method for use in an access and mobility management function. The method comprises transmitting, to a first session management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.

Various embodiments may preferably implement the following features:

receiving, from the first session management function, a request of modifying the session context associated with the protocol data unit session

Preferably, the indication indicates that the session information in the second wireless network node of the protocol data unit session is not valid, and the method further comprises:

receiving, from the first session management function, a request of establishing the session context associated with the protocol data unit session.

The present disclosure relates to a wireless device comprising a first session management function. The wireless device comprises:

a communication unit, configured to:

receive, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises first wireless terminal location information associated with a first wireless communication node,

transmit, to a second session management function, a session context request associated with the protocol data unit session,

receive, from the second session management function, a session context associated with the protocol data unit session, wherein the session context comprises second wireless terminal location information associated with a second wireless network node.

Various embodiments may preferably implement the following feature:

Preferably, the wireless device further comprises a processor configured to perform any of aforementioned wireless communication methods.

The present disclosure relates to a wireless device comprising a second session management function. The wireless device comprises:

a communication unit, configured to:

receive, from a first session management function, a session context request associated with a protocol data unit session, and

transmit, to the first session management function, a session context comprising second wireless terminal location information associated with a second wireless network node.

Various embodiments may preferably implement the following feature:

a communication unit, configured to receive, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.

Various embodiments may preferably implement the following feature:

The present disclosure relates to a wireless device comprising an access and mobility management function. The wireless device comprises a communication unit, configured to transmit, to a first session management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.

Various embodiments may preferably implement the following feature:

The present disclosure relates to a computer program product comprising a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a wireless communication method recited in any one of foregoing methods.

The exemplary embodiments disclosed herein are directed to providing features that will become readily apparent by reference to the following description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the present disclosure.

Thus, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. Additionally, the specific order and/or hierarchy of steps in the methods disclosed herein are merely exemplary approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present disclosure. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the present disclosure is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims.

FIG. 1 shows a schematic diagram of a 5 ^th generation system (5GS) architecture according to an embodiment of the present disclosure.

FIG. 2 shows a schematic diagram of a process according to an embodiment of the present disclosure.

FIG. 3 shows a schematic diagram of a process according to an embodiment of the present disclosure.

FIG. 4 shows a schematic diagram of a process according to an embodiment of the present disclosure.

FIG. 5 shows a flowchart of a method according to an embodiment of the present disclosure.

FIG. 6 shows a flowchart of a method according to an embodiment of the present disclosure.

FIG. 7 shows a flowchart of a method according to an embodiment of the present disclosure.

FIG. 8 shows a flowchart of a method according to an embodiment of the present disclosure.

FIG. 9 shows an example of a schematic diagram of a wireless terminal according to an embodiment of the present disclosure.

FIG. 10 shows an example of a schematic diagram of a wireless network node according to an embodiment of the present disclosure.

FIG. 1 shows a schematic diagram of a 5 ^th generation system (5GS) architecture according to an embodiment of the present disclosure. The network functions shown in FIG. 1 are illustrating in the following:

1. UE: User Equipment.

2. RAN (Radio Access Network) :

The RAN (node) provides a Uu (radio) interface towards the UE, N2 interface (s) (control plane (CP) ) towards AMF (s) and N3 interface (s) (user plane (UP) ) towards UPF (s) .

3. AMF (Access and Mobility Management function) :

The AMF includes the following functionalities: registration management, connection management, Reachability management and Mobility management. The AMF also performs an access authentication and an access authorization. The AMF is the non-access stratum (NAS) security termination and relays the SM NAS between the UE and SMF, etc. In addition, the AMF performs an SMF/I-SMF selection function during a packet data unit (PDU) session establishment procedure and a UE mobility procedure.

4. SMF (Session Management Function) :

The SMF includes the following functionalities: session establishment, modification and release, UE IP address allocation &management (including optional authorization functions) , selection and control of UP function, downlink data notification, etc. The SMF service area is a collection of UPF service areas of all UPFs which can be controlled by the SMF.

5. I-SMF (Intermediate SMF) :

An I-SMF that is inserted, changed or removed from a PDU session when the UE moves outside of the service area of the serving SMF/I-SMF. The I-SMF has an N16a interface towards the SMF and has an N11 interface towards the AMF. Based on the UE mobility, the I-SMF may be relocated from a source I-SMF to a target I-SMF. The target I-SMF may retrieve the session related context from the source I-SMF via an N38 interface.

6. UPF (User plane function) :

The UPF is controlled by the SMF via an N4 interface. The UPF includes the following functionalities: serving as an anchor point for intra-/inter-radio access technology (RAT) mobility, packet routing & forwarding, traffic usage reporting, quality of service (QoS) handling for the user plane, downlink packet buffering and downlink data notification triggering, etc. The UPF service area is an area consisting of one or more tracking area (s) within which PDU session associated with the UPF can be served by RAN nodes via an N3 interface between the RAN and the UPF without the need to add a new UPF in between or to remove/re-allocate the UPF. The anchor UPF (A-UPF) is kept unchanged during the UE mobility.

7. I-UPF (Intermediate UPF) :

The I-UPF is inserted/relocated when the UE moves outside of the A-UPF service area. The I-UPF uses an N3 tunnel to connect the RAN node and uses an N9 tunnel to connect the A-UPF. The I-UPF may also provide a traffic offloading function to route the identified uplink traffic to local data network.

8. Data Network:

The data network provides data services such as operator services, internet access services or 3rd party services.

During the UE mobility, the AMF may determine that an I-SMF may need to be inserted, relocated or removed from the PDU session. The target I-SMF may retrieve the session related context from the source I-SMF. The session related context includes the following information:

1. SMF related context, including the PDU session ID, network slice related information, SMF ID, UPF N9 tunnel information, QoS flow related information, etc. Note that the RAN N3 tunnel information is not transferred to the target I-SMF in the existing standard specification.

2. AMF related information, including the AMF ID.

The target I-SMF uses the session context information to re-establish the user plane of the PDU session.

During the procedure of relocating the I-SMF, the RAN N3 tunnel information may be available for being reused when the UE is in connected state. However, the source I-SMF does not provide the RAN N3 tunnel information to the target I-SMF in the session related context.

Furthermore, even if the RAN N3 tunnel information is provided to the target I-SMF, the target I-SMF may not know whether the provided RAN N3 tunnel information can be reused for the PDU session. In addition, the target I-SMF cannot differentiate between whether to establish a new session context in the RAN node or whether to update the existing session context in RAN node.

In an embodiment, the present disclosure proposes the following solutions to resolve the abovementioned issue:

1. The source I-SMF provides the RAN N3 tunnel information and/or associated UE location information to the target I-SMF in the session related context.

2. Based on the associated UE location information, the target I-SMF determines whether to reuse the RAN N3 tunnel information.

FIG. 2 shows a schematic diagram of a procedure according to an embodiment of the present disclosure. The procedure shown in FIG. 2 may be applied in the scenario of a packet data network (PDN) connection being handed over from an evolved packet system (EPS) to the 5GS. In addition, the procedure shown in FIG. 2 shows how the I-SMF is relocated during a UE registration procedure. For a home routed case, the I-SMF may be replaced by visiting SMF (V-SMF) and the I-UPF may be replaced by visiting UPF (V-UPF) . The procedure shown in FIG. 2 may be used in the network architecture shown in FIG. 1 and comprises the following steps.

In step 201, the UE establishes an PDN connection with home route in a 4G network (i.e. EPS) . The UE moves to an area of 5G network and an EPS to 5GS handover procedure is performed. During the EPS to 5GS handover procedure, the AMF selects a default I-SMF1 based on a single-network slice selection assistant information (S-NSSAI) configured for the interworking and uses the I-SMF1 for the PDU session. The SMF allocates and provides the correct S-NSSAI of the PDU session to the AMF.

In step 202, after the EPS to 5GS handover procedure, the UE initiates a UE registration procedure via the RAN node. The UE is in a connected state. The RAN has an active UE context and an N3 tunnel between the RAN node and an I-UPF1 has been established during the EPS to 5GS handover procedure.

In step 203, based on the S-NSSAI of the PDU session received from the SMF, the AMF determines that the I-SMF1 is not suitable for the PDU session. Under such conditions, the AMF reselects an I-SMF2 for the PDU session and initiates an I-SMF relocation procedure by invoking an Nsmf_CreateSMContext_Request message to the I-SMF2. The Nsmf_CreateSMContext_Request message includes a PDU session ID, a SM context ID, the S-NSSAI, UE location information, an access type, an RAT type, and an operation type. The SM context ID points to the I-SMF1. The AMF sets the operation type as "UP activate" , to indicate an establishment of N3 tunnel User Plane resources for the PDU session (s) . The AMF determines the access type and the RAT type based on a global RAN node ID associated with the N2 interface.

In an embodiment, the AMF determines that the RAN node of the PDU session does not change and the session context in the RAN node is valid. The AMF provides an indication to the I-SMF2 based on the determining result. This indication may be used by the I-SMF2 for determining whether the session context in the RAN node is valid, e.g., for being reused.

In step 204, the I-SMF2 retrieves the SM context from the I-SMF1 by invoking Nsmf_PDUSession_Context request message (e.g. comprising SM context type, SM context ID, etc. ) . For example, the I-SMF2 may use the SM context ID received from the AMF for this service operation. The SM context ID is used for the recipient of Nsmf_PDUSession_Context_Request, so as to determine the targeted PDU session. The SM context type indicates that requested information comprises all SM context, i.e. PDN connection context and 5G SM context. If the I-SMF2 determines that the session context in the RAN node is valid, the I-SMF2 may also send an indication to I-SMF1 to request the RAN N3 tunnel information.

In step 205, the I-SMF1 responds the I-SMF2 with the SM context of the indicated PDU session. When the UE is in a connection management connected (CM_CONNECTED) state (e.g. RRC connected state or RRC inactive state) , the SM context may include the session information associated with the RAN node. For example, the session information includes RAN N3 tunnel information and/or UE location information. The RAN N3 tunnel information includes an IP address and tunnel endpoint identifier of the RAN node for the PDU session. The UE location information may include a tracking area identity (TAI) , and/or NR cell identity, and/or global RAN Node identity. The UE location information is provided by the AMF and stored in the I-SMF1 when the PDU session is handed over from the EPS. The SM context may also comprise the S-NSSAI of the PDU session (i.e. the S-NSSAI configured for interworking) .

In step 206, the I-SMF2 selects a new I-UPF (i.e. I-UPF2) . For example, the I-SMF2 selects the new I-UPF based on the received SM context (e.g. S-NSSAI and/or UE location information) received from the AMF. The I-SMF2 initiates a N4 Session Establishment to the new I-UPF.

In an embodiment, the I-SMF2 determines whether the session information in (e.g. associated with) the RAN node is valid or not based on the UE location information and/or the S-NSSAI of the PDU session. For example, the I-SMF2 may determine the session information associated with the RAN node is not valid when corresponding network slice of the PDU session changes. As an alternative or in addition, the I-SMF2 may determine the session information associated with the RAN node is still valid and/or the RAN N3 tunnel information received from the I-SMF1 can be reused if UE location information received from AMF and the UE location information received from the I-SMF1 are identical (even if the network slices are different) .

If the session information associated with the RAN node is valid and the RAN N3 tunnel information is reused, the I-SMF2 provides the RAN N3 tunnel information to the I-UPF2 and the I-UPF2 provides I-UPF N3 tunnel information and I-UPF N9 tunnel information to the I-SMF2.

In step 207, the I-SMF2 invokes Nsmf_PDUSession_Update Request (e.g. comprising the SM context ID, the I-UPF DL tunnel information, the SM context ID at the I-SMF2, the Access Type, the RAT Type) towards the SMF. The I-SMF2 uses the SM context ID received from the I-SMF1 for this service operation.

In step 208, the SMF initiates an N4 session modification towards the PDU session anchor (PSA) UPF. The SMF provides the I-UPF N9 tunnel information to the PSA UPF.

In step 209, the SMF responds the I-SMF2 with an Nsmf_PDUSession_Update Response.

In step 210, the I-SMF2 sends an Nsmf_PDUSession_CreateSMContext Response (e.g. comprising N2 SM information (e.g. PDU session ID, QFI (s) , QoS profile (s) , CN N3 Tunnel Info, S-NSSAI) , N1 SM Container, Cause) ) to the AMF. The CN N3 Tunnel information (Info) is the I-UPF N3 Tunnel Info of the I-UPF2. If the session information associated with the RAN node is valid, the N2 SM information includes a request of modifying the session information associated with the RAN node; otherwise the N2 SM information includes a request of establishing new session context in the RAN node.

In step 211, the AMF sends a registration accept (message) to the UE, wherein the registration accept (message) includes the new allowed NSSAI and/or the new registration area.

In step 212, the AMF transmits, to the RAN node, an N2 Request (N2 SM information received from SMF, security context, Mobility Restriction List) . The N2 SM information includes the I-UPF N3 Tunnel Info of the I-UPF2.

In step 213, uplink data may be sent towards the I-UPF2 and then forwarded to UPF.

In step 214, the RAN transmits, to the AMF, an N2 Request Ack (List of PDU sessions To Be Established with N2 SM information (AN Tunnel Info) ) . The N2 Request Ack message may include new N2 SM information when the RAN determines to change the old RAN N3 tunnel information which are associated with the old network slice.

In step 215, the AMF transmits, to the I-SMF2, an Nsmf_PDUSession_UpdateSMContext Request (N2 SM information, RAT Type, Access Type) per PDU session. The N2 SM information may include the new RAN N3 tunnel information.

In step 216, the I-SMF2 may update the new RAN N3 tunnel information to the I-UPF2 in an N4 Session update procedure.

In step 217, the I-SMF2 sends an Nsmf_PDUSession_UpdateSMContext Response to the AMF.

In step 218, downlink data may be send over the new N3 tunnel to the RAN node.

In step 219, the AMF sends an Nsmf_ReleaseSMContext_Request to the I-SMF1, to release the resource of the PDU session.

In step 220, the I-SMF1 releases the PDU session resource in the I-UPF2.

In step 221, the I-SMF1 sends an Nsmf_ReleaseSMContext_Response (message) to the AMF.

FIG. 3 shows a schematic diagram of a procedure according to an embodiment of the present disclosure. In the procedure shown in FIG. 3, a PDU session is established via a RAN node (e.g. RAN1) with an I-SMF (e.g. I-SMF1) insertion and the UE moves into radio resource control (RRC) inactive state. Next, the UE moves to the service area of another RAN node (e.g. RAN2) and initiates a UE registration procedure via the RAN2. Under such conditions, the I-SMF for the PDU session is relocated (e.g. to another I-SMF (e.g. I-SMF2) ) .

More specifically, the UE accesses the network via the RAN1 and establishes a PDU session with the I-SMF1 in the control plane. The RAN1 node may decide that the UE enters the RRC inactive state and releases the RRC connection over the Uu interface while keeping the UE context in the RAN1. Note that the UE state in the AMF may still be the Connected mode. In addition, the N3 Tunnel may also be kept in both the RAN1 and the I-UPF1 (step 301) .

In step 302, the UE stays in the RRC inactive state and moves outside of the registration area. Under such conditions, the UE initiates a UE registration procedure via a new RAN node RAN2.

In step 303, the RAN2 may obtain UE context including the AMF information from the RAN1 and forward the registration request message to the AMF. The RAN2 may select the old AMF or select another new AMF.

In step 304, the AMF determines that the I-SMF1 is not suitable for the PDU session based on the current UE location. Thus, the AMF reselects an I-SMF2 for the PDU session and initiates an I-SMF relocation procedure by invoking the Nsmf_CreateSMContext_Request to the I-SMF2. This message includes PDU session ID, SM context ID, S-NSSAI, UE location info, Access Type, RAT Type, Operation Type. The SM context ID points to the I-SMF1. The AMF sets the Operation Type to "UP activate" to indicate establishment of N3 tunnel User Plane resources for the PDU session (s) . The AMF determines the Access Type and the RAT Type based on the Global RAN Node ID associated with the N2 interface.

If a new AMF is selected by the RAN2, the new AMF retrieves UE context from the old AMF. In the UE context the old AMF may include the old RAN1 information if the UE is in CONNECTED state. The new AMF then determine that the RAN node changes and the session context in the old RAN node is not valid. The AMF may provide an indication to the I-SMF2. This indication may be used by the I-SMF2 to determine whether the session context in the RAN node is not valid.

In step 305, the I-SMF2 retrieves SM context from the I-SMF1 by invoking Nsmf_PDUSession_Context Request (SM context type, SM context ID) . The I-SMF2 uses SM context ID received from the AMF for this service operation. SM context ID is used for the recipient of Nsmf_PDUSession_Context Request in order to determine the targeted PDU session. The SM context type indicates that the requested information is all SM context, i.e. PDN Connection Context and 5G SM context.

In step 306, the I-SMF1 responds the I-SMF1 with the SM context of the indicated PDU session. When the UE is in CM_CONNECTED state, the SM context may include the session information associated with the RAN node. For example, the session information may comprise the RAN1 N3 tunnel information and/or the UE location information. The RAN1 N3 tunnel information includes the IP address and Tunnel Endpoint Identifier in the RAN1 node for the PDU session. The UE location information may include the TAI, or NR cell identity, or global RAN node identity. The UE location information is provided by the AMF and stored in the I-SMF1. The SM context may also contain the S-NSSAI of the PDU session.

In step 307, the I-SMF2 selects a new I-UPF (i.e. I-UPF2) . For example, the I-SMF2 selects the I-UPF2 based on the received SM context, e.g. S-NSSAI, and/or UE location information received from the AMF. The I-SMF2 initiates a N4 Session Establishment to the selected I-UPF2.

In this embodiment, the I-SMF2 may determine whether the session information associated with the RAN node is valid or not based on the UE location information. For example, the I-SMF2 may determine that the session information is not valid and not to reuse the RAN N3 tunnel information if the UE location information received from the AMF and the UE location information received from the I-SMF1 are not identical. Alternatively the I-SMF2 may determine whether the session information associated with the RAN node is valid or not based on the indication from AMF, as described in step 304.

If the session information associated with the RAN node is not valid and the RAN N3 tunnel information is not reused, the I-SMF2 does not provide the RAN N3 tunnel information to the I-UPF2.

In step 308, the I-SMF2 invokes Nsmf_PDUSession_Update Request (SM context ID, new I-UPF DL tunnel information, SM context ID at I-SMF, Access Type, RAT Type) towards the SMF. The I-SMF2 uses the SM context ID at SMF received from I-SMF1 for this service operation.

In step 309, the SMF initiates N4 Session Modification toward the PDU session Anchor UPF. The SMF provides the new I-UPF N9 tunnel information to the PSA UPF.

In step 310, the SMF responds the I-SMF2 with Nsmf_PDUSession_Update Response.

In step 311, the I-SMF2 sends a Nsmf_PDUSession_CreateSMContext Response (N2 SM information (PDU session ID, QFI (s) , QoS profile (s) , CN N3 Tunnel Info, S-NSSAI) , N1 SM Container, Cause) ) to the AMF. The CN N3 Tunnel Info is the I-UPF N3 Tunnel Info of the new I-UPF2. If the session information associated with the RAN node is not valid, the N2 SM information includes a request of establishing a new session context associated with the RAN node.

In step 312, the AMF sends Registration Accept to the UE, including the new Allowed NSSAI, new Registration Area.

In step 313, the AMF transmits the N2 Request (e.g. N2 SM information received from SMF, security context, and/or Mobility Restriction List) to the RAN. The N2 SM information includes the I-UPF N3 Tunnel Info of the new I-UPF2.

In step 314, the uplink data can be sent towards the new I-UPF2 and then forwarded to UPF.

In step 315, the RAN transmits the N2 Request Ack (e.g. comprising list of PDU sessions to be established with the N2 SM information (RAN N3 Tunnel Info) ) to the AMF. The RAN2 allocates RAN N3 tunnel information for the PDU session and send it in the N2 SM information towards the I-SMF2.

In step 316, the AMF transmits Nsmf_PDUSession_UpdateSMContext Request (N2 SM information, RAT Type, Access Type) per PDU session to the I-SMF2. The N2 SM information includes the new RAN N3 tunnel information.

In step 317, the I-SMF2 may update the I-UPF2 with the new RAN N3 tunnel information in an N4 Session update procedure.

In step 318, the I-SMF sends Nsmf_PDUSession_UpdateSMContext_Response to the AMF.

In step 319, the downlink data can be sent over the new N3 tunnel to the RAN node.

In step 320, the AMF determines to release the UE context in the old RAN1. The AMF sends N2 UE context release request to the RAN1.

In step 321, the RAN1 releases the UE context and send N2 UE context release complete to the AMF.

In step 322, the AMF sends Nsmf_ReleaseSMContext_Request to I-SMF1 to release the resource of the PDU session.

In step 323, the I-SMF1 releases the PDU session resource in the I-UPF2.

In step 324, the I-SMF1 sends Nsmf_ReleaseSMContext_Response to the AMF.

FIG. 4 shows a schematic diagram of a procedure according to an embodiment of the present disclosure. In FIG. 4, a PDU session is established with I-SMF1 insertion and an application function (AF) initiates an influence request procedure to offload traffic to local DN identified by the DNAI. The I-SMF1 does not support the requested DNAI and the I-SMF for the PDU session needs to be relocated.

Specifically, the UE establishes a PDU session in the 5GS, wherein the I-SMF1 is inserted in the control plane. Afterward, the AF sends a message to 5G core network to influence the traffic routing towards the local Data Network which is identified by a DNAI. The policy control function (PCF) sends, to the SMF, PCC rule (s) including the DNAI (s) for the PDU sessions by invoking Npcf_SMPolicyControl_UpdateNotify service operation. Based on the received DNAI (s) information, the SMF may subscribe the UE mobility event notification to the AMF (e.g. the notification associated with the UE moves into or out of Area of Interest) . The SMF determines the target DNAI (s) which are applicable to the current UE location (step 401) .

In step 402, the SMF invokes a Nsmf_PDUSession_StatusNotify message if the SMF and the associated I-SMF1 cannot serve the target DNAI. The content of the Nsmf_PDUSession_StatusNotify message includes the target DNAI information which may indicate that the I-SMF selection is expected. This is to trigger the AMF to (re) select a suitable I-SMF for the PDU session. The target DNAI is used for selecting the (I-) SMF, which controls the UPF connecting to the target DNAI.

In step 403, the I-SMF invokes Nsmf_PDUSession_SMContextStatusNotify message to send the target DNAI information for existing PDU session to AMF.

In step 404, if the I-SMF selection is expected, the AMF selects an I-SMF2 which can serve the target DNAI for the existing PDU session. The AMF initiates the I-SMF relocation procedure by invoking the Nsmf_CreateSMContext_Request message to the I-SMF2. This message includes PDU session ID, SM context ID, UE location info, Access Type, RAT Type, Operation Type. The SM context ID points to the I-SMF1. The AMF sets the Operation Type to "UP activate" , to indicate an establishment of N3 tunnel User Plane resources for the PDU session (s) only if the UE is in the connected state. The AMF determines the Access Type and the RAT Type based on the Global RAN Node ID associated with the N2 interface.

When the UE is in CONNECTED state, the AMF then determines that the RAN node does not change and the session context in the RAN node is valid. The AMF then provides an indication to the I-SMF2 based on the result. This indication may be used by the I-SMF2 to determine whether the session context in the RAN node is valid.

In step 405, the I-SMF2 retrieves the SM context from the I-SMF1 by invoking Nsmf_PDUSession_Context Request (SM context type, SM context ID) . The I-SMF2 uses SM context ID received from the AMF for this service operation. SM context ID is used by the recipient of Nsmf_PDUSession_Context Request in order to determine the targeted PDU session. SM context type indicates that the requested information is all SM context, i.e. PDN Connection Context and 5G SM context. If the I-SMF2 determines that the session context in the RAN node is valid, the I-SMF2 may also send an indication to I-SMF1, to request the RAN N3 tunnel information.

In step 406, the I-SMF1 responds with the SM context of the indicated PDU session. If the UE is in the connected state, the SM context of the PDU session may include session information associated with the RAN node. For example, the session information may comprise the RAN N3 tunnel information and UE location information. The RAN N3 tunnel information includes the IP address and Tunnel Endpoint Identifier in the RAN node for the PDU session. The UE location information may include the Tracking Area Identity (TAI) , or the NR Cell Identity, or the Global Ran Node Identity. The UE location information is provided by the AMF and stored in the I-SMF1.

In step 407, the I-SMF2 selects a new I-UPF2. For example, the I-SMF2 selects a new I-UPF2 based on the received SM context (e.g. UE location information received from the AMF) . The I-SMF2 initiates a N4 Session Establishment to a new I-UPF2.

The I-SMF2 determines whether the session information in the RAN node is valid or not based on the UE location information. For example, the I-SMF2 may determine that the session information associated with the RAN node is valid and determine to reuse the RAN N3 tunnel Information if the UE location received from AMF and the UE location information received from the I-SMF1 are identical.

If the session information associated with the RAN node is valid and the RAN N3 tunnel information is reused the I-SMF2 provides the RAN N3 tunnel information to the I-UPF2. The I-UPF2 provide I-UPF N3 tunnel information and I-UPF N9 tunnel information to the I-SMF2.

In step 408, the I-SMF2 invokes the Nsmf_PDUSession_Update Request (e.g. comprising SM context ID, new I-UPF DL tunnel information, SM context ID at I-SMF, Access Type, RAT Type, DNAI list supported by the I-SMF2) towards the SMF. The I-SMF2 uses the SM context ID at SMF received from I-SMF1 for this service operation.

In step 409, the SMF initiates an N4 session modification toward the PDU session anchor (PSA) UPF. The SMF provides the new I-UPF N9 tunnel information to the PSA UPF.

In step 410, the SMF responds to the I-SMF2 with the Nsmf_PDUSession_Update Response (e.g. comprising the DNAI (s) of interest for this PDU session, N4 information) . The SMF determines the DNAI (s) of interest for this PDU session based on the DNAI list supported by the I-SMF2 and the requested DNAI (s) in the PCC rules for the PDU session. The SMF provides to I-SMF with DNAI (s) of interest for this PDU session for local traffic steering. The SMF generates N4 information for local traffic offload based on the available DNAI (s) indicated by the I-SMF, PCC rules associated with these DNAI (s) and charging requirement. The SMF provide N4 information to the I-SMF for how the traffic shall be detected, enforced, monitored in UPF (s) controlled by the I-SMF. I-SMF uses this N4 information to derive rules installed in the I-UPF (s) controlled by the I-SMF. Based on the DNAI (s) of interest the I-SMF2 selects a local PSA UPF to access the local Data Network and send the N4 information to the local PSA UPF.

In step 411, the Downlink data can be sent over the N3 tunnel to the RAN node.

In step 412, the I-SMF2 sends a Nsmf_PDUSession_CreateSMContext Response (N2 SM information (e.g. comprising PDU session ID, QFI (s) , QoS profile (s) , CN N3 Tunnel Info, S-NSSAI) , Cause) ) to the AMF. The CN N3 Tunnel Info is the I-UPF N3 Tunnel Info of the new I-UPF2. If the session information associated with the RAN node is valid the N2 SM information includes a request of modifying the session context associated with the RAN node.

In step 413, the AMF transmits the N2 Request (e.g. comprising N2 SM information received from SMF, security context, Mobility Restriction List) to the RAN. The N2 SM information includes the I-UPF N3 Tunnel Info of the new I-UPF2.

In step 414, the uplink data can be sent towards the new I-UPF2 and then forwarded to UPF.

In step 415, the RAN transmits the N2 Request Ack (e.g. comprising List of PDU sessions To Be Established with N2 SM information) to the AMF.

In step 416, the AMF transmits the Nsmf_PDUSession_UpdateSMContext Request (e.g. comprising N2 SM information, RAT Type, Access Type) per PDU session to the SMF.

In step 417, the I-SMF sends the Nsmf_PDUSession_UpdateSMContext Response to the AMF.

In step 418, the AMF sends the Nsmf_ReleaseSMContext_Request to I-SMF1 to release the resource of the PDU session.

In step 419, the I-SMF1 releases the PDU session resources in the I-UPF1.

In step 420, the I-SMF1 sends the Nsmf_ReleaseSMContext_Response to the AMF.

FIG. 5 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 5 may be used in a first (intermediate) SMF (e.g. target I-SMF, abovementioned I-SMF2, a first wireless device comprising/performing the functionalities of the I-SMF/SMF) and comprises the following steps.

Step 501: Receive, from an AMF, a context create request for a PDU.

Step 502: Transmit, to a second SMF, a session context request associated with the PDU.

Step 503: Receive, from the second SMF, a session context associated with the PDU.

In FIG. 5, the first SMF receives a context create request for a PDU session, wherein the context create request comprises first wireless terminal location information (e.g. UE location information) associated with a first wireless communication node. For example, the first wireless network node may be selected (by AMF) for the PDU session. The first SMF transmits a session context request associated with the PDU session to a second SMF, to retrieve the session context of the PDU session from the second SMF. Next, the first SMF receives the session context from the second SMF. In this embodiment, the received session context comprises second wireless terminal location information associated with a second wireless network node. For example, the second wireless network node may be the old serving network node of the PDU session. Based on the first wireless terminal location information and the second wireless terminal location information, the first SMF determines whether session information (e.g. N3 tunnel information) associated with the wireless network node of the PDU session can be reused.

In an embodiment, the first wireless terminal location information and the second wireless terminal location information are the same (i.e. the first wireless network node is the second wireless network node) . That is, the session information associated with the wireless network node of the PDU session is available for being reused. Under such conditions, the first SMF transmits a request of modifying the session context associated with the PDU session to the AMF (e.g. step 210 or 412) .

In an embodiment, the first wireless terminal location information and the second wireless terminal location information are different (i.e. the first wireless network node is not the second wireless network node) . That is, the session information associated with the wireless network node of the PDU session cannot be reused. In this embodiment, the first SMF transmits a request of establishing a new session context associated with the PDU session to the AMF (e.g. step 210 or 311) .

In an embodiment, the received session context comprises tunnel information with an interface (e.g. N3 tunnel/interface) between the second wireless network node and a first UPF and the first wireless terminal location information and the second wireless terminal location information are the same. In this embodiment, the first SMF may use the tunnel information for the PDU session, e.g., for subsequent communications. As an alternative or in addition, the first SMF may transmit the tunnel information to a second UPF.

In an embodiment, the tunnel information comprises at least one of an internet protocol address or a tunnel endpoint identifier of the PDU session in the second wireless communication node.

In an embodiment, the first/second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.

FIG. 6 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 6 may be used in a second (intermediate) SMF (e.g. source I-SMF, abovementioned I-SMF1 or a second wireless device performing/comprising the functionalities of the SMF/I-SMF) and comprises the following steps.

Step 601: Receive, from a first SMF, a session context request associated with a PDU session.

Step 602: Transmit, to the first SMF, a session context associated with the PDU session.

In FIG. 6, the second SMF receives a session context request associated with a PDU session from a first SMF. In response to the session context request, the second SMF transmits a session context of the PDU session to the first SMF. Note that, the session context comprises second wireless terminal location information associated with f a second wireless network node, as a reference of whether reusing session information associated with the wireless network node of the PDU session.

In an embodiment, the second wireless terminal location information is received from an AMF.

In an embodiment, the second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.

In an embodiment, the transmitted session context further comprises the tunnel information associated with the interface between the second wireless network node and a first user plane function (e.g. N3 tunnel information) .

In an embodiment, the tunnel information is received from the AMF.

FIG. 7 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 7 may be used in a first SMF (e.g. I-SMF2) and comprises the following step:

Step 701: Receive, from an AMF, a context create request for a PDU session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the PDU session.

In FIG. 7, the first SMF receives a context create request for a PDU session from an AMF. In this embodiment, an indication associated a validity of session information in a second wireless network node of the PDU session is included in the context create request. Based on the indication, the first SMF determines whether the session information in the second wireless network node of the PDU session is valid and/or whether to reuse the session information in the second wireless network node of the PDU session.

In an embodiment, the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid. In this embodiment, the first SMF transmits a session context request associated with the PDU session to a second SMF, wherein the session context request comprises an indication of requesting tunnel information associated with an interface between the second wireless network node of the PDU session and a first UPF.

In an embodiment, the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid. In this embodiment, the first SMF receives (retrieves) the session context of the PDU session from a second SMF, wherein the session context comprises tunnel information associated with an interface (e.g. N3 tunnel information) between the second wireless network node and a first UPF. The first SMF may uses (e.g. reuses) the tunnel information for the PDU session and/or transmit the tunnel information to a second UPF.

In an embodiment, the tunnel information comprises at least one of an IP address or a tunnel endpoint identifier of the PDU session in the second wireless communication node.

In an embodiment, the indication indicates that the session information in a second wireless network node of the PDU session is valid. In this embodiment, the first SMF may transmit a request of modifying the session context associated with the PDU session to the AMF.

In an embodiment, the indication indicates that the session information in the second wireless network node of the PDU session is not valid. Under such a condition, the first SMF transmits a request of modifying the session context associated with the PDU session to the AMF.

FIG. 8 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 8 may be used in an AMF and comprises the following step:

Step 801: Transmit, to a first SMF, a context create request for a PDU session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the PDU session.

In FIG. 8, the AMF may select the first SMF for the PDU session (e.g. because of UE mobility) and transmits a context create request for the PDU session to the first SMF. In this embodiment, an indication associated a validity of session information in a second wireless network node of the PDU session is included in the context create request. For example, the AMF may generate the indication based on whether the second wireless communication node of the PDU session changes.

In an embodiment, the indication indicates that the session information in the wireless network node of the PDU session is valid (e.g. the wireless network node of the PDU session does not change) . Under such a condition, the AMF may receive a request of modifying the session context associated with the protocol data unit session from the first SMF.

In an embodiment, the indication indicates that the session information in the wireless network node of the PDU session is not valid (e.g. the wireless network node of the PDU session changes) . In this embodiment, the AMF may receive request of establishing the session context associated with the protocol data unit session from the first SMF.

FIG. 9 relates to a schematic diagram of a wireless terminal 90 according to an embodiment of the present disclosure. The wireless terminal 90 may be a user equipment (UE) , a mobile phone, a laptop, a tablet computer, an electronic book or a portable computer system and is not limited herein. The wireless terminal 90 may include a processor 900 such as a microprocessor or Application Specific Integrated Circuit (ASIC) , a storage unit 910 and a communication unit 920. The storage unit 910 may be any data storage device that stores a program code 912, which is accessed and executed by the processor 900. Embodiments of the storage unit 912 include but are not limited to a subscriber identity module (SIM) , read-only memory (ROM) , flash memory, random-access memory (RAM) , hard-disk, and optical data storage device. The communication unit 920 may a transceiver and is used to transmit and receive signals (e.g. messages or packets) according to processing results of the processor 900. In an embodiment, the communication unit 920 transmits and receives the signals via at least one antenna 922 shown in FIG. 9.

In an embodiment, the storage unit 910 and the program code 912 may be omitted and the processor 900 may include a storage unit with stored program code.

The processor 900 may implement any one of the steps in exemplified embodiments on the wireless terminal 90, e.g., by executing the program code 912.

The communication unit 920 may be a transceiver. The communication unit 920 may as an alternative or in addition be combining a transmitting unit and a receiving unit configured to transmit and to receive, respectively, signals to and from a wireless network node (e.g. a base station) .

FIG. 10 relates to a schematic diagram of a wireless network node 100 according to an embodiment of the present disclosure. The wireless network node 100 may be a satellite, a base station (BS) , a network entity, a Mobility Management Entity (MME) , Serving Gateway (S-GW) , Packet Data Network (PDN) Gateway (P-GW) , a radio access network (RAN) node, a next generation RAN (NG-RAN) node, a gNB, an eNB, a gNB central unit (gNB-CU) , a gNB distributed unit (gNB-DU) a data network, a core network or a Radio Network Controller (RNC) , and is not limited herein. In addition, the wireless network node 100 may comprise (perform) at least one network function such as an access and mobility management function (AMF) , a session management function (SMF) , a user place function (UPF) , a policy control function (PCF) , an application function (AF) , etc. The wireless network node 100 may include a processor 1000 such as a microprocessor or ASIC, a storage unit 1010 and a communication unit 1020. The storage unit 1010 may be any data storage device that stores a program code 1012, which is accessed and executed by the processor 1000. Examples of the storage unit 1012 include but are not limited to a SIM, ROM, flash memory, RAM, hard-disk, and optical data storage device. The communication unit 1020 may be a transceiver and is used to transmit and receive signals (e.g. messages or packets) according to processing results of the processor 1000. In an example, the communication unit 1020 transmits and receives the signals via at least one antenna 1022 shown in FIG. 10.

In an embodiment, the storage unit 1010 and the program code 1012 may be omitted. The processor 1000 may include a storage unit with stored program code.

The processor 1000 may implement any steps described in exemplified embodiments on the wireless network node 100, e.g., via executing the program code 1012.

The communication unit 1020 may be a transceiver. The communication unit 1020 may as an alternative or in addition be combining a transmitting unit and a receiving unit configured to transmit and to receive, respectively, signals to and from a wireless terminal (e.g. a user equipment or another wireless network node) .

While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand exemplary features and functions of the present disclosure. Such persons would understand, however, that the present disclosure is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any one of the above-described exemplary embodiments.

It is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any one of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A skilled person would further appreciate that any one of the various illustrative logical blocks, units, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, various forms of program or design code incorporating instructions (which can be referred to herein, for convenience, as "software" or a "software unit” ) , or any combination of these techniques.

To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, units, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure. In accordance with various embodiments, a processor, device, component, circuit, structure, machine, unit, etc. can be configured to perform one or more of the functions described herein. The term “configured to” or “configured for” as used herein with respect to a specified operation or function refers to a processor, device, component, circuit, structure, machine, unit, etc. that is physically constructed, programmed and/or arranged to perform the specified operation or function.

Furthermore, a skilled person would understand that various illustrative logical blocks, units, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, units, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein. If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium.

Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "unit" as used herein, refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various units are described as discrete units; however, as would be apparent to one of ordinary skill in the art, two or more units may be combined to form a single unit that performs the associated functions according embodiments of the present disclosure.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present disclosure. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present disclosure with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the present disclosure. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below.

Claims

A wireless communication method for use in a first session management function, the method comprising:

receiving, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises first wireless terminal location information associated with a first wireless communication node,

transmitting, to a second session management function, a session context request associated with the protocol data unit session, and

receiving, from the second session management function, a session context associated with the protocol data unit session, wherein the session context comprises second wireless terminal location information associated with a second wireless network node.
The wireless communication method of claim 1, wherein the first wireless terminal location information and the second wireless terminal location information are the same,

wherein the session context further comprises tunnel information associated with an interface between the second wireless network node and a first user plane function,

wherein the method further comprises at least one of:

using the tunnel information for the protocol data unit session, or

transmitting, to a second user plane function, the tunnel information.
The wireless communication method of claim 2, wherein the tunnel information comprises at least one of an internet protocol address or a tunnel endpoint identifier of the protocol data unit session in the second wireless communication node.
The wireless communication method of any of claims 1 to 3, wherein the first wireless terminal location information and the second wireless terminal location information are the same, and

wherein the method further comprises:

transmitting, to the access and mobility management function, a request of modifying the session context associated with the protocol data unit session.
The wireless communication method of claim 1, wherein the first wireless terminal location information and the second wireless terminal location information are different, and

wherein the method further comprises:

transmitting, to the access and mobility management function, a request of establishing the session context associated with the protocol data unit session.
The wireless communication method of any of claims 1 to 6, wherein each of the first wireless terminal location information and the second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.
A wireless communication method for use in a second session management function, the method comprising:

receiving, from a first session management function, a session context request associated with a protocol data unit session, and

transmitting, to the first session management function, a session context comprising second wireless terminal location information associated with a second wireless network node.
The wireless communication method of claim 7, further comprising:

receiving, from an access and mobility management function, the second wireless terminal location information.
The wireless communication method of claim 7 or 8, wherein the second wireless terminal location information comprises at least one of a tracking area identity, a new radio cell identity, or a global radio access network node identity.
The wireless communication method of any of claims 7 to 9, wherein the session context further comprises tunnel information associated with an interface between the second wireless network node and a first user plane function.
The wireless communication method of claim 10, further comprising:

receiving, from an access and mobility management function, the tunnel information.
The wireless communication method of claim 10 or 11, wherein the tunnel information comprises at least one of an internet protocol address or a tunnel endpoint identifier of the protocol data unit session in the second wireless communication node.
A wireless communication method for use in a first session management function, the method comprising:

receiving, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.
The wireless communication method of claim 13, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid, and

wherein the method further comprises:

transmitting, to a second session management function, a session context request associated with the protocol data unit session, wherein the session context request comprises an indication of requesting tunnel information associated with an interface between the second wireless network node and a first user plane function.
The wireless communication method of claim 13 or 14, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid,

wherein the method further comprises:

receiving, from a second session management function, a session context of the protocol data unit session, wherein the session context comprises tunnel information associated with an interface between the second wireless network node and a first user plane function, and

wherein the method further comprises at least one of:

using the tunnel information for the protocol data unit session, or

transmitting, to a second user plane function, the tunnel information.
The wireless communication method of claim 14 or 15, wherein the tunnel information comprises at least one of an internet protocol address or a tunnel endpoint identifier of the protocol data unit session in the second wireless communication node.
The wireless communication method of any of claims 13 to 16, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid, and

wherein the method further comprises:

transmitting, to the access and mobility management function, a request of modifying the session context associated with the protocol data unit session.
The wireless communication method of claim 13, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is not valid, and

wherein the method further comprises:

transmitting, to the access and mobility management function, a request of establishing the session context associated with the protocol data unit session.
A wireless communication method for use in an access and mobility management function, the method comprising:

transmitting, to a first session management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.
The wireless communication method of claim 19, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is valid, and

wherein the method further comprises:

receiving, from the first session management function, a request of modifying the session context associated with the protocol data unit session.
The wireless communication method of claim 19, wherein the indication indicates that the session information in the second wireless network node of the protocol data unit session is not valid, and

wherein the method further comprises:

receiving, from the first session management function, a request of establishing the session context associated with the protocol data unit session.
A wireless device comprising a first session management function, the wireless device comprising:

a communication unit, configured to:

receive, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises first wireless terminal location information associated with a first wireless communication node,

transmit, to a second session management function, a session context request associated with the protocol data unit session, and

receive, from the second session management function, a session context associated with the protocol data unit session, wherein the session context comprises second wireless terminal location information associated with a second wireless network node
The wireless device of claim 21, further comprising a processor configured to perform a wireless communication method of any one of claims 2 to 6.
A wireless device comprising a second session management function, the wireless device comprising:

a communication unit, configured to:

receive, from a first session management function, a session context request associated with a protocol data unit session, and

transmit, to the first session management function, a session context comprising second wireless terminal location information associated with a second wireless network node.
The wireless device of claim 24, further comprising a processor configured to perform a wireless communication method of any one of claims 8 to 12.
A wireless device comprising a first session management function, the wireless device comprises:

a communication unit, configured to receive, from an access and mobility management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.
The wireless device of claim 25, further comprising a processor configured to perform a wireless communication method of any one of claims 14 to 18.
A wireless device comprising an access and mobility management function, the wireless device comprises:

a communication unit, configured to transmit, to a first session management function, a context create request for a protocol data unit session, wherein the context create request comprises an indication associated a validity of session information in a second wireless network node of the protocol data unit session.
The wireless device of claim 27, further comprising a processor configured to perform a wireless communication method of claim 20 or 21.
A computer program product comprising a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a wireless communication method recited in any one of claims 1 to 21.