WO2024230021A1

WO2024230021A1 - Wireless communication method and device thereof

Info

Publication number: WO2024230021A1
Application number: PCT/CN2023/116610
Authority: WO
Inventors: Jinguo Zhu; Shuang Liang; Menghan WANG
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2023-09-01
Filing date: 2023-09-01
Publication date: 2024-11-14
Anticipated expiration: 2026-03-01

Abstract

A wireless communication method for use in a wireless network node. The method comprises determining a session management function (SMF) of a protocol data unit (PDU) session, and transmitting, to the SMF, a session management message of the PDU session.

Description

WIRELESS COMMUNICATION METHOD AND DEVICE THEREOF

TECHNICAL FIELD

This document is directed generally to wireless communications, and in particular to 5G communications.

BACKGROUND

In 5G era, an AMF (access and mobility management function) relays Session Management messages between UE (user equipment) and an SMF (session management function) . Because of complicated interactions between the AMF and the SMF, the communications between the AMF and the SMF are not efficient and make whole network system more complex.

SUMMARY

This document relates to methods, systems, and devices of a PDU (protocol data unit) session management mechanism, and in particular to methods, systems, and devices for the PDU session management mechanism without interactions between the AMF and the SMF.

The present disclosure relates to a wireless communication method for use in a wireless network node. The method comprises:

determining a session management function (SMF) of a protocol data unit (PDU) session, and

transmitting, to the SMF, a session management message of the PDU session.

Various embodiments may preferably implement the following features:

Preferably, the wireless network node is a radio access network (RAN) node.

Preferably, the session management message comprises a PDU session establishment request.

Preferably, the session management message comprises at least one of: location information of a wireless terminal associated with the PDU session, an access type, a radio access technology type, or a subscription permanent identifier of the wireless terminal associated with the PDU session.

Preferably, the wireless communication method further comprises: receiving, from the SMF, a resource request for at least one quality of service (QoS) flow of the PDU session.

Preferably, the resource request comprises at least one of: at least one QoS profile of the at least one QoS flow, or N3 tunnel information of a user plane function (UPF) of the PDU session.

Preferably, the session management message comprises a PDU session deactivation request of the PDU session.

Preferably, the session management message comprises a PDU session release request of the PDU session.

Preferably, the wireless communication method further comprises: receiving, from a wireless terminal, a non-access stratum (NAS) message associated with the session management message.

Preferably, the wireless communication method further comprises: receiving, from the SMF, a resource release request of the PDU session.

Preferably, wireless communication method further comprises: transmitting, to the SMF, a resource release acknowledge message.

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

receiving, from a wireless network node, a session management message of a protocol data unit (PDU) session.

Various embodiments may preferably implement the following features:

Preferably, the wireless network node is a radio access network (RAN) node.

Preferably, the wireless communication method further comprises: transmitting, to the wireless network node, a PDU session resource release request of the PDU session.

Preferably, the wireless communication method further comprises: receiving, from the wireless network node, a PDU session resource release acknowledge message.

Preferably, the wireless communication method further comprises: receiving, from a unified data management (UDM) , the PDU session release request of the PDU session.

The present disclosure relates to a wireless communication method of a unified data management (UDM) . The method comprises:

receiving, from an access and mobility management function (AMF) , a deregistration request of a protocol data unit (PDU) session, and

transmitting, to a session management function (SMF) , a PDU session release request of the PDU session.

Various embodiments may preferably implement the following features:

Preferably, the wireless communication method further comprises: deleting information corresponding to the AMF from subscription information of a wireless terminal of the PDU session.

Preferably, the wireless communication method further comprises: labeling a wireless terminal of the PDU session as a deregistered status in subscription information of the wireless terminal.

The present disclosure relates to a wireless network node. The wireless network node comprises:

a processor, configured to determine a session management function (SMF) of a protocol data unit (PDU) session, and

a communication unit, configured to transmit, to the SMF, a session management message of the PDU session.

Various embodiments may preferably implement the following feature:

Preferably, the processor is further configured to perform any of the aforementioned wireless communication methods.

The present disclosure relates to a wireless device. The wireless device comprises:

a communication unit, configured to receive, from a wireless network node, a session management message of a protocol data unit (PDU) session.

Various embodiments may preferably implement the following features:

Preferably, the wireless device comprises/is a session management function (SMF) .

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

a communication unit, configured to:

receive, from an access and mobility management function (AMF) , a deregistration request of a protocol data unit (PDU) session, and

transmit, to a session management function (SMF) , a PDU session release request of the PDU session.

Various embodiments may preferably implement the following feature:

Preferably, the wireless device comprises/is a unified data management.

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 invention is specified by the independent claims. Preferred embodiments are defined in the dependent claims. In the following description, although numerous features may be designated as optional, it is nevertheless acknowledged that all features comprised in the independent claims are not to be read as optional.

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of a network according to an embodiment of the present disclosure;

FIG. 2 shows a schematic diagram of a PDU Session establishment procedure according to an embodiment of the present disclosure;

FIG. 3 shows a schematic diagram of a UE registration procedure according to an embodiment of the present disclosure;

FIG. 4 shows a schematic diagram of a PDU session establishment procedure according to an embodiment of the present disclosure;

FIG. 5 shows a schematic diagram of a procedure according to an embodiment of the present disclosure;

FIG. 6 shows a schematic diagram of a UE triggering PDU Session Release procedure according to an embodiment of the present disclosure;

FIG. 7 shows a schematic diagram of a Deregistration procedure according to an embodiment of the present disclosure;

FIG. 8 shows an example of a schematic diagram of a wireless terminal according to an embodiment of the present disclosure;

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

FIG. 10 shows a flowchart of a method according to an embodiment of the present disclosure;

FIG. 11 shows a flowchart of a method according to an embodiment of the present disclosure;

FIG. 12 shows a flowchart of a method according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure provides a PDU session management mechanism that does not involve interactions between the AMF and the SMF. Since there is no interaction between the AMF and the SMF, a Mobility restriction mechanism is therefore simplified.

In the present disclosure, the term “info” or “Info” refers to information.

In the present disclosure, a device comprising a network function may refer to the network function or the device performing at least part of functionalities of the network function.

FIG. 1 shows a schematic diagram of a network (architecture) according to an embodiment of the present disclosure. In FIG. 1, the network comprises the following network functions/entities:

1) UE: User Equipment;

2) RAN: Radio Access Network.

In the present disclosure, the RAN manages the radio resource, delivers user data received over an N3 interface to the UE and delivers user data from the UE over the N3 interface. The RAN performs mapping between DRBs (Dedicated Radio Bearers) and the QoS (Quality-of-Service) flows in a PDU session.

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 access authentication and access authorization. The AMF is a NAS (non-access stratum) security termination and relays the SM (session management) NAS between the UE and the SMF, …, etc.

4) SMF: Session Management Function.

The SMF includes the following functionalities: session establishment, modification and release, UE IP (internet protocol) address allocation &management (including optional authorization functions) , selection and control of UP (User Plane) function, downlink data notification. The SMF controls the UPF via an N4 association. The SMF provides PDR (s) (Packet Detection Rule (s) ) to the UPF to instruct how to detect user data traffic, FAR (Forwarding Action Rule) , QER (QoS Enforcement Rule) , URR (Usage Reporting Rule) to instruct the UPF how to perform the user data traffic forwarding, QoS handling and usage reporting for the user data traffic detected by using the PDR.

5) UPF: User Plane Function.

The UPF includes the following functionalities: serving as an anchor point for intra-/inter-radio access technology (RAT) mobility and the external session point of interconnect to Data Network, packet routing &forwarding as indicated by SMF, traffic usage reporting, quality of service (QoS) handling for the UP, downlink packet buffering and downlink data notification triggering, …, etc. In addition, a GTP-U (GPRS UP) tunnel is used over an N3 interface between the RAN and UPF. The GTP-U tunnel is per PDU session. For downlink traffic, the UPF binds the downlink traffic to QoS flows within the GTP-U tunnel of the PDU session by using the FARs received from the SMF. For uplink traffic, the RAN transfers the user plane traffic to QoS flows identified by the UE.

6) PCF: Policy Control Function.

The PCF provides QoS policy rules to control plane functions, to enforce the rules. The PCF (s) transform (s) the AF requests into PCC rules that apply to the PDU Sessions.

7) UDM: Unified Data Management.

The UDM performs the generation of the 3GPP AKA Authentication Credential, access authorization based on subscription data, Serving NF Registration Management of the UE (e.g. storing serving AMF for UE, storing serving SMF for UE's PDU Session) and Subscription management, …, etc. The UDM accesses the UDR to retrieve UE subscription data and stores the UE context into the UDR. The UDM and the UDR may be deployed together.

FIG. 2 shows a schematic diagram of a PDU Session establishment procedure according to an embodiment of the present disclosure. The PDU Session establishment procedure shown in FIG. 2 comprises the following steps:

Step 201 (From UE to AMF) : NAS Message (S-NSSAI (s) (Single Network Slice Selection Assistance Information (s) ) , DNN (data network name) , PDU Session ID, Request type, N1 SM (session management) container (e.g., PDU Session Establishment Request) ) .

Step 202: The AMF selects an SMF for the PDU Session via an NRF (Network Repository Function) or local configuration. In case of via the NRF, the AMF provides the DNN and S-NSSAI to the NRF and the NRF selects an SMF to the AMF together with the Service Area of the selected SMF.

Step 203: The AMF sends a Nsmf_PDUSession_CreateSMContext Request (PDU Session ID, SM Context ID, UE location info, Access Type, RAT (radio access technology) Type, Operation Type) to the selected SMF.

Step 204: The SMF sends a Nsmf_PDUSession_CreateSMContext Response to the AMF.

Step 205: The SMF determines that the PCC (policy and charging control) authorization is required and requests to establish an SM Policy Association with the PCF by invoking Npcf_SMPolicyControl_Create operation.

Step 206: The PCF makes the authorization and the policy decision. The PCF answers with a Npcf_SMPolicyControl_Create response. In its response, the PCF may provide PCC rules to the SMF. The SMF selects an UPF and requests the UPF to allocate an N3 tunnel for the uplink data.

Step 207: The SMF sends to AMF an Namf_Communication_N1N2MessageTransfer. The message contains parameters such as PDU Session ID, N2 SM information (PDU Session ID, QFI (s) , QoS Profile (s) , N3 tunnel of the UPF) and N1 SM container (PDU Session Establishment Accept) .

Step 208 (AMF to (R) AN) : N2 PDU Session Request (N2 SM information, NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) ) .

Step 209 ( (R) AN to UE) : The (R) AN may issue AN specific signaling exchange with the UE that is related with the information received from the SMF. For example, in case of a NG-RAN, an RRC Connection Reconfiguration may take place with the UE establishing the necessary NG-RAN resources related to the QoS (quality-of-service) profile (s) .

In an embodiment, the (R) AN also allocates (R) AN Tunnel Info for the PDU Session.

In an embodiment, the (R) AN forwards the NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) to the UE.

Step 210 ( (R) AN to AMF) : N2 PDU Session Response (PDU Session ID, Cause, N2 SM information) .

In an embodiment, the (R) AN Tunnel Info corresponds to the Access Network address of the N3 tunnel corresponding to the PDU Session.

Step 211 (AMF to SMF) : Nsmf_PDUSession_UpdateSMContext Request (SM Context ID, N2 SM information, Request Type) .

In an embodiment, the AMF forwards the N2 SM information received from the (R) AN to the SMF.

Step 212: (SMF to AMF) : Nsmf_PDUSession_UpdateSMContext Response (Cause) .

In the procedure shown in FIG. 2, both the SM NAS message (e.g., PDU Session Establishment Request and PDU Session Establishment Accept) and N2 SM information are transferred via the AMF, which makes the procedure complicated and inefficient. The present disclosure further discloses a procedure of handling the PDU session without involving the AMF. In addition, because the mobility management and the session management may be split, the present disclosure also provides a deregistration procedure without interactions between the AMF and the SMF.

In the present disclosure, the RAN may communicate with the SMF directly without involving the AMF. For example, if the N2 interface is service based, the RAN may discover the SMF via the NRF and communicates with the selected SMF directly.

FIG. 3 shows a schematic diagram of a UE registration procedure according to an embodiment of the present disclosure. In FIG. 3, the AMF provides the Mobility restriction information to the RAN. Specifically, the UE registration procedure shown in FIG. 3 comprises the following steps:

Step 301: The UE sends a NAS Registration Request message to the RAN. The NAS Registration Request message includes the Registration type, GUTI (Globally Unique Temporary Identifier) , Security parameters, UE MM Core Network Capability and other parameters.

Step 302: The RAN selects an AMF and forwards the Registration Request message to the selected AMF (i.e., new AMF in FIG. 3) .

Step 303: The new AMF may decide to retrieve the UE context including the SUPI (Subscription Permanent Identifier) from the old AMF. The new AMF sends a UE context request message to the old AMF identified by the GUTI provided by the UE.

Step 304: The old AMF returns the UE context including the SUPI to the new AMF.

Step 305: The AMF performs a UE authentication procedure. In this procedure, the UE is authenticated by the network and the network is also authenticated by the UE. In this procedure, the AMF provides security context to the RAN, to protect the NAS message exchange between the UE and the RAN.

Step 306: After the success of authentication, the AMF retrieves UE subscription from the UDM. The AMF may discover the UDM by using the SUPI. The AMF sends a UE subscription Data request (message) towards the UDM, where the UE subscription Data request includes the SUPI and the AMF address.

Step 307: The UDM stores the AMF address and returns the UE subscription data towards the AMF.

Step 308: The AMF includes the NAS Registration Accept message in the N2 message. The NAS Registration message is sent to the UE and includes the Registration Area and the new GUTI and the Mobility Restriction information. The N2 message is sent to the RAN and includes the Mobility Restriction Information.

Step 309: The RAN sends the NAS Registration Accept message over the Uu interface to the UE.

Step 310: The UE stores the Registration Area, GUTI and the Mobility Restriction Information, and send Registration Complete message to the RAN.

Step 311: The RAN forwards the Registration Complete message towards the AMF.

After this procedure, the UE is successfully registered in the network. Both the UE and RAN are provided with the Mobility Restriction Information.

FIG. 4 shows a schematic diagram of a PDU session establishment procedure according to an embodiment of the present disclosure. In the procedure shown in FIG. 4, the RAN discovers the SMF and communicates with the SMF directly without involving the AMF. Specifically, the PDU session establishment procedure comprises the following steps:

Step 401: The UE sends NAS Message PDU Session Establishment Request to the RAN. This message contains at least S-NSSAI (s) , DNN, PDU Session ID, Request type, etc.

Step 402: The RAN selects an SMF for the PDU Session via NRF or local configuration. In case of via NRF, the RAN provides the DNN and S-NSSAI to the NRF. The NRF may return a list of SMFs supporting the DNN and the S-NSSAI to the RAN and the RAN selects an SMF. Then RAN forwards the PDU Session Establishment Request to the selected SMF, together with UE location info, Access Type, RAT Type and SUPI.

Step 403: The SMF retrieves the UE subscription data of the S-NSSAI and DNN from the UDM by using the SUPI, S-NSSAI and DNN.

Step 404: The SMF determines the QoS flow parameters based on subscription and PCC rule. The SMF selects an UPF to serve the PDU session and configure the UPF with the detection rules and traffic handling rules for the QoS flows. The UPF allocates N3 tunnel information for the uplink traffic.

Step 405: The SMF sends a RAN resource Request to the RAN to request radio resource allocation for the QoS flows of the PDU session. This message including the QoS profiles of the QoS flows and the N3 tunnel information of the UPF.

Step 406: The RAN communicates with the UE to allocate the radio resource for the QoS flows. RAN also allocates RAN N3 Tunnel Info for the PDU Session.

Step 407: The RAN sends a Radio resource response to the SMF, wherein the Radio resource response includes the RAN N3 Tunnel Info for the PDU Session.

Step 408: The SMF provides the RAN N3 Tunnel Info for the PDU Session to the UPF.

Step 409: The SMF sends PDU Session Registration Request to UDM. This message includes the SMF address, PDU Session ID. The UDM stores the PDU Session ID and the SMF address and returns the response to the SMF.

Step 410: The SMF sends PDU Session Establishment Accept to the RAN. This message may include a UE IP address for the PDU session. As an alternative, the SMF may use user plane to allocate the UP IP address to the UE.

Step 411: The RAN forwards the PDU Session Establishment Accept to the UE.

After this procedure, the PDU Session is established and the PDU Session information is stored in the UDM. Note that, in the procedure shown in FIG. 4, the interactions between the AMF and the SMF are avoided.

FIG. 5 shows a schematic diagram of a procedure according to an embodiment of the present disclosure. In FIG. 5, when/if the RAN determines to deactivate the PDU Session (e.g., because the UE moves to a Not Allowed area) , the PDU Session is kept in the core network and the radio resource may be released. Specifically, the procedure shown in FIG. 5 comprises the following steps:

Step 500: If/When the UE moves into a Not Allowed Area, the RAN determines to deactivate the user plane resource for any existing PDU Sessions (of the UE) because the UE is not allowed to use any user plane resource in the network in the Not Allowed Area.

Step 501: The RAN sends PDU Session Deactivation Request towards the SMF of the existing PDU Sessions. This message may include the PDU Session ID.

Step 502: The SMF sends a RAN resource Release request to the RAN, to delete the radio resource of the PDU Session.

Step 503: The RAN sends a RAN resource release (message) to the UE to release the radio resource of the PDU Session.

Step 504: The UE sends a RAN resource release ACK to the RAN.

Step 505: The RAN sends the RAN resource Release ACK to the SMF.

Step 506: The SMF sends N4 modification to the UPF to remove the N3 tunnel information of the RAN.

Step 507: The UPF sends N4 modification ACK to the SMF.

FIG. 6 shows a schematic diagram of a UE triggering PDU Session Release procedure according to an embodiment of the present disclosure. In FIG. 6, it is assumed that if/when the UE is in the connected state and the RAN stores the PDU Session information including the PDU Session ID and the associated SMF address. The RAN may also receive the PDU Session information from the AMF or from a database in the network. Specifically, the UE triggering PDU Session Release procedure shown in FIG. 6 comprises the following steps:

Step 601: The UE sends a NAS Message (PDU Session Release Request) to the RAN. The PDU Session Release Request includes the PDU Session ID.

Step 602: The RAN forwards the NAS message (PDU Session Release Request) towards the SMF of the PDU session identified by the PDU Session ID.

Step 603: The SMF sends a PDU Session Deregistration Request towards the UDM, to remove the PDU Session ID and the associated SMF address.

Step 604: The UDM removes the PDU Session ID and the SMF address of the PDU Session. The UDM provides a response to the SMF.

Step 605: The SMF sends a RAN resource Release Request to the RAN, to request the radio resource release for the QoS flows of the PDU session. This message includes the PDU Session ID and a NAS message PDU Session Release Command.

Step 606: The RAN communicates with the UE for releasing the radio resources and sends the NAS message PDU Session Release Command to the UE.

Step 607: The UE responses the RAN resource release and sends the NAS PDU Session Release ACK to the RAN.

Step 608: The RAN sends Radio resource release ACK (NAS PDU Session Release ACK) to the SMF.

Step 609: The SMF sends N4 release to the UPF, to release the user plane resource.

Step 610: The UPF sends N4 release response to the SMF.

FIG. 7 shows a schematic diagram of a Deregistration procedure according to an embodiment of the present disclosure. In FIG. 7, the UDM sends PDU Session release to the SMF, to remove the PDU session. Specifically, the Deregistration procedure shown in FIG. 7 comprises the following steps:

Step 701: The UE sends NAS Message (De-Registration Request) towards the RAN. This message includes the GUTI.

Step 702: The RAN forwards the De-Registration Request towards the AMF identified by the GUTI.

Step 703: When/If the AMF receives the deregistration Request from the UE or when/if the AMF determines that the UE is within the Forbidden Area or when/after a configured deregistration timer configured in the AMF expires, the AMF determines that the UE should be deregistered from the network. The AMF marks the UE as deregistered and sends the De-Registration Request towards the UDM.

Step 704: The UDM removes the AMF address in the UE subscription or marks the UE as deregistered. The UDM sends De-Registration Response to the AMF.

Step 705: The AMF sends De-Registration Accept to the UE.

Step 706: Since the UE is deregistered, the UDM sends PDU Session Release Request to the SMF (s) of the existing PDU Sessions. This message includes PDU Session ID (s) . In an embodiment, step 706 (e.g., the transmission of PDU Session Release Request) is triggered by step 703 (e.g., the reception of De-Registration Request) .

Step 707: The SMF triggers a PDU Session release procedure (e.g., steps 605 to 610 in FIG. 6) .

FIG. 8 relates to a schematic diagram of a wireless terminal 80 according to an embodiment of the present disclosure. The wireless terminal 80 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 80 may include a processor 800 such as a microprocessor or Application Specific Integrated Circuit (ASIC) , a storage unit 810 and a communication unit 820. The storage unit 810 may be any data storage device that stores a program code 812, which is accessed and executed by the processor 800. Embodiments of the storage unit 810 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 820 may a transceiver and is used to transmit and receive signals (e.g., messages or packets) according to processing results of the processor 800. In an embodiment, the communication unit 820 transmits and receives the signals via at least one antenna 822 shown in FIG. 8.

In an embodiment, the storage unit 810 and the program code 812 may be omitted and the processor 800 may include a storage unit with stored program code.

The processor 800 may implement any one of the steps in exemplified embodiments on the wireless terminal 80, e.g., by executing the program code 812.

The communication unit 820 may be a transceiver. The communication unit 820 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. 9 relates to a schematic diagram of a wireless network node 90 according to an embodiment of the present disclosure. The wireless network node 90 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 90 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 90 may include a processor 900 such as a microprocessor or 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. Examples of the storage unit 910 include but are not limited to a SIM, ROM, flash memory, RAM, hard-disk, and optical data storage device. The communication unit 920 may be 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 example, 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. The processor 900 may include a storage unit with stored program code.

The processor 900 may implement any steps described in exemplified embodiments on the wireless network node 90, e.g., via 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 terminal (e.g., a user equipment or another wireless network node) .

In an embodiment, the UDM may perform:

- receiving Deregistration request from the AMF,

- removing the AMF address and/or marking the UE as deregistered in the UE subscription, and

- sending PDU Session Release request towards the SMF of the existing PDU Sessions.

In an embodiment, the SMF may perform:

- receiving PDU Session Release message from the UDM,

- sending PDU Session Release command towards the UE, and

- sending Radio Resource release request towards the RAN.

In an embodiment, the RAN may perform:

- receiving NAS SM (Session Management) message (e.g., establishment, release, modification) from the UE, wherein this NAS message includes PDU Session ID,

- determining the SMF of the PDU Session,

- forwarding the NAS SM message towards the SMF of the PDU Session.

FIG. 10 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 10 may be used in a wireless network node (e.g., RAN (node) ) and comprises:

Step 1001: Determine an SMF of a PDU session.

Step 1002: Transmit, to the SMF, an SM message of the PDU session.

In FIG. 10, the wireless network node determines/selects an SMF of/for a PDU session itself and transmits an SM message (e.g., PDU session establishment/release/modification//de-registration) of the PDU session to the determined/selected SMF. In this way, interactions between the AMF and the SMF can be omitted during the corresponding procedure of the PDU session, simplified the corresponding procedure and making the corresponding procedure more efficient.

In an embodiment, the wireless network node receives a NAS (SM) message of the PDU session from a UE. In this embodiment, the NAS (SM) message may be PDU session establishment/release/modification/de-registration request. As an alternative or in addition, the NAS (SM) message is comprised in or associated with the SM message transmitted from the RAN to the SMF.

In an embodiment, the SM message comprises/is a PDU session establishment request. In this embodiment, the SM message comprises at least one of: location information of a wireless terminal (e.g., UE) associated with the PDU session, an access type, a RAT type, or an SUPI of the wireless terminal associated with the PDU session.

In an embodiment of SM message comprising the PDU session establishment request, the wireless network node may receive a resource request for QoS flow (s) of the PDU session from the SMF. The resource request may comprise at least one of: QoS profile (s) of the QoS flow (s) , or N3 tunnel information of a UPF of the PDU session.

In an embodiment, the SM message comprises/is a PDU session deactivation request of the PDU session.

In an embodiment, the SM message comprises/is a PDU session release request of the PDU session.

In an embodiment, the wireless network node may receive a resource release request of the PDU session from the SMF. In this embodiment, the wireless network node may further transmit a resource release ACK message to the SMF.

FIG. 11 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 11 may be used in an SMF (e.g., a wireless device, a wireless device comprising the SMF) and comprise the following step:

Step 1101: Receive, from a wireless network node, an SM message of a PDU session.

In FIG. 11, the SMF receives an SM message of a PDU session from a wireless network node (e.g., BS, RAN (node) ) , rather than an AMF. In response to the reception of the SM message, the SMF performs corresponding procedure.

In an embodiment, the SMF may transmit a resource release request of the PDU session to the wireless network node. In this embodiment, the SMF may receive a resource release ACK message from the wireless network node.

In an embodiment, the SMF may receive a PDU session release request of the PDU session from a UDM. The transmission of the resource release request of the PDU session to the wireless network node may be triggered by or in response to the (reception of) PDU session release request from the UDM.

FIG. 12 shows a flowchart of a method according to an embodiment of the present disclosure. The method shown in FIG. 12 may be used in a UDM (e.g., a wireless device, a wireless device comprising the UDM) and comprise the following steps:

Step 1201: Receive, from AMF, a deregistration request of a PDU session.

Step 1202: Transmit, to an SMF, a PDU session release request of the PDU session.

In FIG. 12, the UDM receives a deregistration request of a PDU session from an AMF. In response to the (reception of) deregistration request, the UDM transmits a PDU session release request of the PDU session to an SMF.

In an embodiment, the UDM deletes information corresponding to the AMF from subscription information of a wireless terminal (e.g., UE) of the PDU session.

In an embodiment, the UDM labels/marks a wireless terminal of the PDU session as a deregistered status in subscription information of the wireless terminal.

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 to 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 the claims. 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 wireless network node, the method comprising:

determining a session management function (SMF) of a protocol data unit (PDU) session; and

transmitting, to the SMF, a session management message of the PDU session.
The wireless communication method of claim 1, wherein the wireless network node is a radio access network (RAN) node.
The wireless communication method of claim 1 or 2, wherein the session management message comprises a PDU session establishment request.
The wireless communication method of claim 3, wherein the session management message comprises at least one of:

location information of a wireless terminal associated with the PDU session;

an access type;

a radio access technology type; or

a subscription permanent identifier of the wireless terminal associated with the PDU session.
The wireless communication method of claim 3 or 4, further comprising:

receiving, from the SMF, a resource request for at least one quality of service (QoS) flow of the PDU session.
The wireless communication method of claim 5, wherein the resource request comprises at least one of:

at least one QoS profile of the at least one QoS flow; or

N3 tunnel information of a user plane function (UPF) of the PDU session.
The wireless communication method of any of claims 1 to 6, wherein the session management message comprises a PDU session deactivation request of the PDU session.
The wireless communication method of any of claims 1 to 7, wherein the session management message comprises a PDU session release request of the PDU session.
The wireless communication method of any of claims 1 to 8, further comprising:

receiving, from a wireless terminal, a non-access stratum (NAS) message associated with the session management message.
The wireless communication method of any of claims 1 to 9, further comprising:

receiving, from the SMF, a resource release request of the PDU session.
The wireless communication method of claim 10, further comprising:

transmitting, to the SMF, a resource release acknowledge message.
A wireless communication method for use in a session management function (SMF) , the method comprising:

receiving, from a wireless network node, a session management message of a protocol data unit (PDU) session.
The wireless communication method of claim 12, wherein the wireless network node is a radio access network (RAN) node.
The wireless communication method of claim 12 or 13, wherein the session management message comprises a PDU session establishment request.
The wireless communication method of claim 14, wherein the session management message comprises at least one of:

location information of a wireless terminal associated with the PDU session;

an access type;

a radio access technology type; or

a subscription permanent identifier of the wireless terminal associated with the PDU session.
The wireless communication method of claim 14 or 15, further comprising:

transmitting, to the wireless network node, a resource request for at least one quality of service (QoS) flow of the PDU session.
The wireless communication method of claim 16, wherein the resource request comprises at least one of:

at least one QoS profile of the at least one QoS flow; or

N3 tunnel information of a user plane function (UPF) of the PDU session.
The wireless communication method of any of claims 12 to 17, wherein the session management message comprises a PDU session deactivation request of the PDU session.
The wireless communication method of any of claims 12 to 18, wherein the session management message comprises a PDU session release request of the PDU session.
The wireless communication method of any of claims 12 to 19, further comprising:

transmitting, to the wireless network node, a PDU session resource release request of the PDU session.
The wireless communication method of claim 20, further comprising:

receiving, from the wireless network node, a PDU session resource release acknowledge message.
The wireless communication method of claim 20 or 21, further comprising:

receiving, from a unified data management (UDM) , the PDU session release request of the PDU session.
A wireless communication method of a unified data management (UDM) , the method comprising:

receiving, from an access and mobility management function (AMF) , a deregistration request of a protocol data unit (PDU) session; and

transmitting, to a session management function (SMF) , a PDU session release request of the PDU session.
The wireless communication method of claim 23, further comprising:

deleting information corresponding to the AMF from subscription information of a wireless terminal of the PDU session.
The wireless communication method of claim 23 or 24, further comprising:

labeling a wireless terminal of the PDU session as a deregistered status in subscription information of the wireless terminal.
A wireless network node, comprising:

a processor, configured to determine a session management function (SMF) of a protocol data unit (PDU) session; and

a communication unit, configured to transmit, to the SMF, a session management message of the PDU session.
The wireless network node of claim 26, wherein the processor is further configured to perform the wireless communication method of any of claims 2 to 11.
A wireless device, comprising:

a communication unit, configured to receive, from a wireless network node, a session management message of a protocol data unit (PDU) session.
The wireless device of claim 28, further comprising a processor configured to perform the wireless communication method of any of claims 13 to 22.
A wireless device, comprising:

a communication unit, configured to:

receive, from an access and mobility management function (AMF) , a deregistration request of a protocol data unit (PDU) session; and

transmit, to a session management function (SMF) , a PDU session release request of the PDU session.
The wireless device of claim 30, further comprising a processor configured to perform the wireless communication method of claim 24 or 25.
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 25.