WO2021093099A1

WO2021093099A1 - Conflict resolution for protocol data unit session registration and de-registration

Info

Publication number: WO2021093099A1
Application number: PCT/CN2019/127583
Authority: WO
Inventors: Jinguo Zhu; Zhijun Li; Tricci So
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2021-05-20
Anticipated expiration: 2022-06-23
Also published as: CN114762450A

Abstract

Methods, apparatus and systems for backward compatible multi-access protocol data unit session (PDU) registration and deregistration are described. One method of digital communication includes receiving, at a network function in a communication network, a request to establish a protocol data unit (PDU) session for a mobile station, wherein the request includes an identifier of the PDU session, making a determination that the identifier matches an identifier of an existing PDU session and that the identifier is not for a multi-access PDU session, and initiate, based on the determination, a release of the existing PDU session towards a session management function in the communication network, wherein the release includes an indication that the session management function is not to send a corresponding de-registration request to a unified data management function in the communication network.

Description

CONFLICT RESOLUTION FOR PROTOCOL DATA UNIT SESSION REGISTRATION AND DE-REGISTRATION

TECHNICAL FIELD

The present document relates to digital communication related to wireless networks.

BACKGROUND

After the release of initial version of the 5G specification, sometimes called Release-15, the Third Generation Partnership Project (3GPP) is already looking at further feature additions to this technology in the upcoming Release-16 revision. The new release is expected to provide additional flexibility to the existing 5G protocols and at the same time be backwards compatible with Release-15 to the extent possible.

SUMMARY

The disclosed technology can be implemented in some embodiments to provide techniques for use by network-side functions such as a mobility management function or a session management function to handle multiple registrations and de-registrations for multi-access protocol data unit (PDU) sessions using a same identifier, which may occur in developing wireless network standards support for multi-access PDU sessions.

In one example aspect, a method implemented in a digital communication network is disclosed. The method includes receiving, at a network function in a communication network, a request to establish a protocol data unit (PDU) session for a mobile station, wherein the request includes an identifier of the PDU session, making a determination that the identifier matches an identifier of an existing PDU session and that the identifier is not for a multi-access PDU session, and initiating, based on the determination, a release of the existing PDU session towards a session management function in the communication network, wherein the release includes an indication that the session management function is not to send a corresponding de-registration request to a unified data management function in the communication network.

In another example aspect, another method for digital communication is disclosed. The method includes receiving, at a session management function of a radio access network, a request to release an existing protocol data unit (PDU) session, the request including an indication about whether the session management function is to send a deregistration request for the existing PDU session to a unified data management function, and determining to refrain from sending the deregistration request due to receiving the indication.

In yet another example aspect, the above described method may be implemented in a digital communication network using a hardware platform that comprises one or more processors.

In yet another example aspect, a computer-program storage medium is disclosed. The computer-program storage medium includes code stored thereon. The code, when executed by a processor, causes the processor to implement a described method.

These, and other, features are described in the present document.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example network-side implementation to support 5G network operation.

FIG. 2 shows an example of messages exchanged during the PDU session establishment procedure.

FIG. 3 shows an example of PDU session establishment in a same serving public land mobile network (PLMN) scenario.

FIG. 4 shows an example of PDU session establishment in a different serving PLMN scenario.

FIG. 5 is an example of a communication network.

FIG. 6 is an example of a hardware platform for implementing one or more methods described in the present document.

FIG. 7 a flowchart for an example method of digital communication.

FIG. 8 a flowchart for another example method of digital communication.

DETAILED DESCRIPTION

FIG. 1 shows the architecture of 5G system. In this architecture, there are the following network functions:

UE, User Equipment.

RAN, Radio Access Network. In 5G, it is NR base station.

AMF, Access and Mobility Management function. This function includes the following functionalities: Registration management, Connection management, Reachability management and Mobility Management. This function also performs the access authentication and access authorization. The AMF is the NAS security termination and relay the SM NAS between UE and SMF, etc.

SMF, Session Management Function: This function 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 controls the UPF via N4 association.

UPF, User plane function. This function includes the following functionalities: serving as an anchor point for intra-/inter-radio access technology (RAT) mobility, packet routing & forwarding, traffic usage reporting, QoS handling for the user plane, downlink packet buffering and downlink data notification triggering, etc. UPF may be deployed as I-UPF (Intermediate UPF) or PDU Session Anchor (PSA) . PSA/UPF is the UPF terminating the N6 interface towards the data network. The I-UPF provides traffic forwarding between the RAN and PSA/UPF. The I-UPF may support "ULCL" (Uplink classifier: offloading uplink traffic based on target IP address) or “BP” (Branching point: offloading uplink traffic based on source IP address) to offload some traffic to local PSA/UPF.

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 policies that apply to PDU Sessions. The PCF provide the AF influenced Traffic Steering Enforcement Control in PCC rules to SMF so the SMF can establish the data path to offload the traffic to local data network.

AF, Application Function. The AF interacts with the 3GPP Core Network in order to provide services, for example to support application influence on traffic routing. Based on operator deployment, Application Functions considered to be trusted by the operator can be allowed to interact directly with relevant Network Functions. Application Functions not allowed by the operator to access directly the Network Functions shall use the external exposure framework via the NEF to interact with relevant Network Functions.

The network functions may be implemented on one or more hardware platforms using one or more processors, one or more network interfaces and/or one or more memories for storing code or data.

In order to obtain the IP service, PDU session is established upon UE request.

UE registers to 5G. The UE may perform Registration procedure either via 3GPP access or via Non-3GPP access. If the UE registration is accepted, the AMF performs AMF Registration to the UDM. The UDM stores the AMF Registration Context, after accepting the AMF Registration request.

1. From UE to AMF: NAS Message (DNN, PDU Session ID, N1 SM container (PDU Session Establishment Request) ) . In order to establish a new PDU Session, the UE generates a new PDU Session ID. The UE initiates the request for PDU Session Establishment procedure by the transmission of a NAS message containing a PDU Session Establishment Request within the N1 SM container. The NAS message sent by the UE is encapsulated by the AN in a N2 message towards the AMF.

2. The AMF selects an SMF based on the requested DNN and other information.

3. The AMF sends Nsmf_PDUSession_CreateSMContext Request (SUPI, DNN, PDU Session ID, AMF ID, N1 SM container (PDU Session Establishment Request) . SUPI (Subscription Permanent Identifier) uniquely identify the UE subscription. The AMF ID is the UE's GUAMI (Globally Unique AMF ID) which uniquely identifies the AMF serving the UE. The AMF forwards the PDU Session ID together with the N1 SM container containing the PDU Session Establishment Request received from the UE.

4. The SMF sends Nudm_SDM_Get Request to the UDM, to retrieve Session Management Subscription data. The UDM sends back the requested data in response message.

5. If the SMF is able to process the PDU Session establishment request, the SMF creates an SM context and responds to the AMF by providing an SM Context Identifier in Nsmf_PDUSession_CreateSMContext Response.

6. The SMF may interact with PCF to perform PCC authorization.

7. The SMF selects a UPF based on the DNN and other information.

8. The SMF sends an N4 Session Establishment Request to the UPF to setup N4 session. The SMF provides Packet detection, enforcement and reporting rules to be installed on the UPF for this PDU Session. If CN Tunnel Info is allocated by the SMF, the CN Tunnel Info is provided to UPF in this step. The UPF acknowledges by sending an N4 Session Establishment Response. If CN Tunnel Info is allocated by the UPF, the CN Tunnel Info is provided to SMF in this step.

9. SMF to AMF: Namf_Communication_N1N2MessageTransfer (PDU Session ID, N2 SM information (PDU Session ID, QFI (s) , QoS Profile (s) , N3 CN Tunnel Info) , N1 SM container (PDU Session Establishment Accept) ) . The N2 SM information carries information that the AMF shall forward to the (R) AN which includes the N3 CN Tunnel Info corresponds to the Core Network address of the N3 tunnel corresponding to the PDU Session, the QoS profiles and the corresponding QFI (QoS Flow Identifier) and the PDU Session ID. The N1 SM container contains the PDU Session Establishment Accept that the AMF shall provide to the UE.

10. AMF to RAN: N2 PDU Session Request (N2 SM information, NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) ) . The AMF sends the NAS message containing PDU Session ID and PDU Session Establishment Accept targeted to the UE and the N2 SM information received from the SMF within the N2 PDU Session Request to the 5G-AN.

11. RAN to UE: The RAN may issue AN specific signaling exchange with the UE that is related with the information received from SMF. For example, in case of a 3GPP RAN, an RRC Connection Reconfiguration may take place with the UE establishing the necessary RAN resources related to the QoS Rules for the PDU Session request. RAN forwards the NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) to the UE. RAN also allocates AN N3 tunnel information for the PDU Session.

12. RAN to AMF: N2 PDU Session Response (PDU Session ID, Cause, N2 SM information (PDU Session ID, AN Tunnel Info, List of accepted/rejected QFI (s))) .

The AN Tunnel Info corresponds to the Access Network address of the N3 tunnel corresponding to the PDU Session.

13. AMF to SMF: Nsmf_PDUSession_UpdateSMContext Request (N2 SM information) .

The AMF forwards the N2 SM information received from (R) AN to the SMF. If the list of rejected QFI (s) is included in N2 SM information, the SMF shall release the rejected QFI (s) associated QoS profiles.

14. The SMF initiates an N4 Session Modification procedure with the PSA/UPF0. The SMF provides AN Tunnel Info to the PSA/UPF0 as well as the corresponding forwarding rules.

15. SMF to UDM: Nudm_UECM_Registration Request (PDU Session ID, SMF Instance ID, DNN, PLMN ID) .

If UDM accepts SMF Registration, it stores the SMF Registration Context and sends response message to the SMF.

After the PDU session establishment, the UE is allocated with IP address. With the allocated IP address, UE can start IP communication with any other IP remote side.

When the PDU session is no longer needed, the UE may request to release the PDU session. After PDU session is successfully released, the SMF sends SMF Deregistration request to the UDM, including the PDU Session ID. The UDM uses the PDU Session ID to locate the stored SMF Registration Context, and removes the stored SMF Registration Context associated with the PDU Session ID, if the SMF Deregistration request is acceptable.

In a digital communication network where user equipment (UE) may release a protocol data unit (PDU) session locally, the PDU session context between the UE and a core network is not synchronized. If the UE initiates a PDU session with an old PDU session ID via the same public land mobile network (PLMN) , the same access and mobility management function (AMF) will detect a PDU session ID conflict because there is an old PDU session with the same PDU session ID. In this case, the AMF will accept a new PDU session ID and release the old PDU session. When the new PDU session is accepted, a new session management function (SMF) will register in Unified Data Management (UDM) with the new PDU session ID. When the old PDU session is released, the old SMF will send deregistration to UDM with the same PDU session ID. Due to the concern of the race condition as a result of the different signaling paths from different network functions, there is no guarantee the registration request and deregistration request from two different SMFs could reach the UDM in proper order. As a result, there is a possibility that the new SMF’s context registration request to UDM is deleted by the old SMF’s context de-registration request.

Furthermore, when the UE registers via different PLMNs and establish the PDU session with different PLMNs with the “same” PDU session ID, the UE will be served by different AMFs. There is no mechanism currently to enable network functions (e.g. AMF and SMF) to detect the conflict associated with a PDU session registration and de-registration with the UDM.

FIG. 3 shows an example of PDU session establishment in a same serving PLMN scenario.

In some embodiments of the disclosed technology, in order to resolve the issue for a different PLMN case, an old AMF subscribes an SMF registration context event from a UDM. When a new SMF sends an SMF registration request to the UDM, the UDM will notify the old AMF of the latest SMF registration context. The old AMF will then detect the PDU session ID is in conflict with another PDU session, and the old AMF should trigger the release of old PDU session. When releasing the old PDU session via an old SMF, the old AMF sends an additional indication to the old SMF to instruct the old SMF not to send SMF deregistration request to the UDM. In this way, the UDM will receive the SMF registration request only from the new SMF, thereby avoiding a potential race condition issue.

In a same serving PLMN scenario, the disclosed technology can be implemented in some embodiments to perform the following actions to avoid the old SMF sending deregistration to UDM.

1. The UE sends PDU Session Establishment Request to the AMF, carrying the PDU Session ID, DNN, S-NSSAI and other information. The AMF selects the SMF1 and establish the PDU Session as required.

2. The UE may release the PDU Session context locally.

3. The UE establish a new PDU Session with the PDU Session ID with the “same” serving AMF.

4. The AMF detects that there is already an PDU Session with same PDU Session ID. If the given PDU session is not a Multi-access PDU session request, the AMF initiates the release of the old PDU session towards the SMF1. In this message a new indication is added to instruct the SMF1 not to send SMF De-registration request to the UDM.

5. The SMF1 releases the PDU session resource and sends response message to AMF.

6. the AMF continues the establishment of new PDU Session. The following call flow is similar as UE establish the PDU Session as described before. Some steps are omitted.

The AMF selects a new SMF2 to serving the PDU session.

7. The AMF sends Nsmf_PDUSession_CreateSMContext Request to the new selected SMF2.

8. The SMF2 sends Nudm_SDM_Get Request to the UDM, to retrieve Session Management Subscription data. The UDM sends back the requested data in response message.

9. The SMF2 sends Namf_Communication_N1N2MessageTransfer to AMF.

10. The SMF2 sends PDU Session Accept message to UE.

11. After the PDU Session established, the SMF2 sends SMF Registration Request to UDM, by invoking Nudm_UECM_Registration Request (PDU Session ID, DNN, SMF2 Instance ID) .

The SMF2 Instance ID contains the NF Instance ID of SMF2.

The UDM accepts SMF Registration request, and stores the SMF Registration Context. The SMF Registration Context consists of PDU Session ID, DNN, SMF2 Instance ID.

The UDM sends SMF Registration response to the SMF2.

In a different serving PLMNs scenario, the disclosed technology can be implemented in some embodiments to perform the following actions.

1. The UE is registered with AMF1 via PLMN1. During the registration the AMF1 subscribes the SMF Registration Context change event with the UDM. The UDM stores the subscription and will notify the AMF1 for any new SMF Registration or SMF De-registration.

2. The UE sends PDU Session Establishment Request to the AMF1, carrying the PDU Session ID, DNN, S-NSSAI and other information. The AMF1 selects the SMF1 and establish the PDU Session as required. The SMF1 registers in the UDM.

3. The UDM sends the SMF1 Registration Context to AMF1. The AMF1 checks the SMF context notified by UDM is aligned with its stored context, it can ignore the notification.

4. The UE may release the PDU Session context locally.

5. The UE registers with AMF2 via second PLMN.

6. The UE establishes a new PDU Session with the same PDU Session ID in the second PLMN.

7. The AMF2 selects a new SMF2 to serving the PDU session.

8. The AMF2 sends Nsmf_PDUSession_CreateSMContext Request to the newly selected SMF2.

9. The SMF2 sends Nudm_SDM_Get Request to the UDM, to retrieve Session Management Subscription data. The UDM sends back the requested data in response message.

10. The SMF2 sends Namf_Communication_N1N2MessageTransfer to AMF.

11. The SMF2 sends PDU Session Accept message to UE.

12. After the PDU Session established, the SMF2 sends SMF Registration Request to UDM, by invoking Nudm_UECM_Registration Request (PDU Session ID, DNN, SMF2 Instance ID) .

The SMF2 Instance ID contains the NF Instance ID of SMF2.

The UDM sends SMF Registration response to the SMF2.

13. The UDM sends the event notification of SMF2 Registration Context to AMF1. The AMF1 detects the SMF context notified by UDM is not aligned with its stored context, and recognizes the conflict for the PDU Session context.

14. The AMF2 initiates the release of the old PDU session towards the SMF1. In this message a new indication is added to instruct the SMF1 not to send SMF De-registration request to the UDM.

15. The SMF1 release the PDU session resource and send response message to AMF1.

FIG. 5 shows an example of a wireless communication system 500 where techniques in accordance with one or more embodiments of the present technology can be applied. A wireless communication system 500 can include one or more base stations (BSs) 505a, 505b, one or

more wireless devices

510a, 510b, 510c, 510d, and a core network 525. A

base station

505a, 505b can provide wireless service to

wireless devices

510a, 510b, 510c and 510d in one or more wireless sectors. In some implementations, a

base station

505a, 505b includes directional antennas to produce two or more directional beams to provide wireless coverage in different sectors.

The core network 525 can communicate with one or

more base stations

505a, 505b. The core network 525 provides connectivity with other wireless communication systems and wired communication systems. The core network may include one or more service subscription databases to store information related to the subscribed

wireless devices

510a, 510b, 510c, and 510d. A first base station 505a can provide wireless service based on a first radio access technology, whereas a second base station 505b can provide wireless service based on a second radio access technology. The

base stations

505a and 505b may be co-located or may be separately installed in the field according to the deployment scenario. The

wireless devices

510a, 510b, 510c, and 510d can support multiple different radio access technologies. The techniques and embodiments described in the present document may be implemented by the base stations of wireless devices described in the present document.

FIG. 6 is a block diagram representation of a portion of a radio station in accordance with one or more embodiments of the present technology can be applied. A radio station 605 such as a base station or a wireless device (or UE) can include processor electronics 610 such as a microprocessor that implements one or more of the wireless techniques presented in this document. The radio station 605 can include transceiver electronics 615 to send and/or receive wireless signals over one or more communication interfaces such as antenna 620. The radio station 605 can include other communication interfaces for transmitting and receiving data. Radio station 605 can include one or more memories (not explicitly shown) configured to store information such as data and/or instructions. In some implementations, the processor electronics 610 can include at least a portion of the transceiver electronics 615. In some embodiments, at least some of the disclosed techniques, method steps or functions are implemented using the radio station 605.

The various technical solutions and embodiments described in the present document may be used in future 3GPP networks for operation of backward compatible MA-PDU sessions. Some embodiments may preferably incorporate some of the following solutions.

1. A method of digital communication (e.g., method 700 in FIG. 7) , comprising: receiving (702) , at a network function in a communication network, a request to establish a protocol data unit (PDU) session for a mobile station, wherein the request includes an identifier of the PDU session, making (704) a determination that the identifier matches an identifier of an existing PDU session and that the identifier is not for a multi-access PDU session, and initiating (706) , based on the determination, a release of the existing PDU session towards a session management function in the communication network, wherein the release includes an indication that the session management function is not to send a corresponding de-registration request to a unified data management function in the communication network. The communication network may be, for example, as described in FIG. 1. The network function may be, for example, AMF1 or AMF2 described with respect to FIG. 4.

In this regard, multi-access PDU sessions, or MA-PDU sessions may refer to a feature in 5G system that allows a single PDU session to be established over multiple accesses, e.g., different radio networks or public land mobile networks PLMNs or via both 3GPP access and Non-3GPP access, of which the PDU session is referred Multi-access PDU (MA PDU) session. When establishing MA-PDU session, UE may not be required to first register with 5G Core Network for both accesses and to initiate the PDU session establishment at the same time. In home-routed roaming case, the 3GPP access and Non-3GPP access of the UE could be served by two different PLMNs, e.g. Home PLMN and Visited PLMN. When the UE first registers with HPLMN directly via its Non-3GPP access, and then establishes a MA-PDU session successfully over its Non-3GPP access. Subsequently, the UE registers with VPLMN via 3GPP access and request establishment of MA-PDU session over the 3GPP access.

2. The method of solution 1, wherein the PDU session is requested via a first radio access network and the existing PDU session is established via a second radio access network.

3. The method of solution 1, wherein the determination is made based on a registration context received from the unified data management function.

4. The method of solution 3, wherein the registration context includes at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.

5. The method of solution 4, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.

6. The method of solution 1, further comprising, upon release of the existing PDU session, causing the session management function to send a response message to an access and mobility management function in the communication network.

7. The method of solution 6, further comprising causing the access and mobility management function to select a new session management function for serving a PDU session.

8. The method of solution 7, further comprising causing the access and mobility management function to send, to the new session management function, a message for creating a session management context request.

9. The method of solution 7, wherein further comprising causing the new session management function to retrieve session management subscription data.

In some implementations, an SMF may preferably incorporate the above methods for performing registration of a PDU session.

10. A method of digital communication (e.g., method 800 depicted in FIG. 8) , comprising: receiving (802) , at a session management function of a radio access network, a request to release an existing protocol data unit (PDU) session, the request including an indication about whether the session management function is to send a deregistration request for the existing PDU session to a unified data management function, and determining to refrain (804) from sending the deregistration request due to receiving the indication. The session management function may be, for example, SMF1 or SMF2 described with respect to FIG. 4. The operation of determining to refrain is different from how SMFs are expected to behave in current version of the 3GPP standard. For example, as further described throughout the present document, the SMF may perform a determination step regarding whether or not deregistration is to be performed based on whether or not the PDU session is a MA-PDU session and will refrain from de-registering in order to enable operation of UEs that use MA-PDU sessions.

11. The method of solution 10, wherein the refraining from sending the deregistration request includes causing an old session management function not to send the deregistration request to the unified data management function.

12. The method of solution 10, further including releasing resources for the existing PDU session, and sending a response message in response to the request indicating that the request was successfully completed.

13. The method of solution 12, further comprising causing the session management function to send a session management function registration request for registering a new session management function.

14. The method of solution 13, further comprising, upon receipt of the session management function registration request, causing the unified data management function to store a registration context including at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.

15. The method of solution 14, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.

16. The method of solution 12, further comprising causing the access and mobility management function to select a new session management function for serving a PDU session.

17. The method of solution 16, further comprising causing the access and mobility management function to send, to the new session management function, a message for creating a session management context request.

18. The method of solution 16, further comprising causing the new session management function to retrieve session management subscription data.

In some implementations, a communication apparatus such as a wireless device, a mobile station, a user equipment (UE) may preferably incorporate the above methods for performing registration of a PDU session.

19. A digital communication apparatus comprising a processor configured to implement a method recited in any one or more of solutions 1-18.

20. A computer readable medium product having processor-executable code for implementing one or more of methods 1-18 stored thereon.

21. A method, apparatus, or system disclosed in the present application.

The various network functions described in the present document may be implemented using one or more hardware platforms (e.g., computers or cloud computing) that comprise a network interface and a processor.

22. A system including one or more processors configured to receive, at a network function in a communication network, a request to establish a protocol data unit (PDU) session for a mobile station, wherein the request includes an identifier of the PDU session, make a determination that the identifier matches an identifier of an existing PDU session and that the identifier is not for a multi-access PDU session, and initiate, based on the determination, a release of the existing PDU session towards a session management function in the communication network, wherein the release includes an indication that the session management function is not to send a corresponding de-registration request to a unified data management function in the communication network.

23. The system of solution 22, wherein the PDU session is requested via a first radio access network and the existing PDU session is established via a second radio access network.

24. The system of solution 22, wherein the determination is made based on a registration context received from the unified data management function.

25. The system of solution 24, wherein the registration context includes at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.

26. The system of solution 25, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.

27. The system of solution 22, wherein the one or more processors are further configured to, upon release of the existing PDU session, cause the session management function to send a response message to an access and mobility management function in the communication network.

28. The system of solution 27, wherein the one or more processors are further configured to cause the access and mobility management function to select a new session management function for serving a PDU session.

29. The system of solution 28, wherein the one or more processors are further configured to cause the access and mobility management function to send, to the new session management function, a message for creating a session management context request.

30. The system of solution 28, wherein the one or more processors are further configured to cause the new session management function to retrieve session management subscription data.

31. A system including one or more processors configured to receive, at a session management function of a radio access network, a request to release an existing protocol data unit (PDU) session, the request including an indication about whether the session management function is to send a deregistration request for the existing PDU session to a unified data management function, and refrain from sending the deregistration request due to receiving the indication.

32. The system of solution 31, wherein the refraining from sending the deregistration request includes causing an old session management function not to send the deregistration request to the unified data management function.

33. The system of solution 31, wherein the one or more processors are further configured to release resources for the existing PDU session, and send a response message in response to the request indicating that the request was successfully completed.

34. The system of solution 33, wherein the one or more processors are further configured to cause the session management function to send a session management function registration request for registering a new session management function.

35. The system of solution 34, wherein, upon receipt of the session management function registration request, the one or more processors are further configured to store a registration context including at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.

36. The system of solution 35, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.

37. The system of solution 33, wherein the one or more processors are further configured to cause the access and mobility management function to select a new session management function for serving a PDU session.

38. The system of solution 37, wherein the one or more processors are further configured to cause the access and mobility management function to send, to the new session management function, a message for creating a session management context request.

39. The system of solution 38, wherein the one or more processors are further configured to cause the new session management function to retrieve session management subscription data.

It will be appreciated that the present document discloses techniques that can be embodied in various embodiments to provide support for MA-PDU session establishment and operation (e.g., registration and deregistration) . One advantageous aspect of the disclosed techniques is to enable backward compatibility with network functions that are unaware of the upcoming multi-access PDU session technology.

The disclosed and other embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document) , in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code) . A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit) .

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

Only a few implementations and examples are described, and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

Claims

A method of digital communication, comprising:

receiving, at a network function in a communication network, a request to establish a protocol data unit (PDU) session for a mobile station, wherein the request includes an identifier of the PDU session;

making a determination that the identifier matches an identifier of an existing PDU session and that the identifier is not for a multi-access PDU session; and

initiating, based on the determination, a release of the existing PDU session towards a session management function in the communication network, wherein the release includes an indication that the session management function is not to send a corresponding de-registration request to a unified data management function in the communication network.
The method of claim 1, wherein the PDU session is requested via a first radio access network and the existing PDU session is established via a second radio access network.
The method of claim 1, wherein the determination is made based on a registration context received from the unified data management function.
The method of claim 3, wherein the registration context includes at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.
The method of claim 4, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.
The method of claim 1, further including, upon release of the existing PDU session, causing the session management function to send a response message to an access and mobility management function in the communication network.
The method of claim 6, further including causing the access and mobility management function to select a new session management function for serving a PDU session.
The method of claim 7, further including causing the access and mobility management function to send, to the new session management function, a message for creating a session management context request.
The method of claim 7, further including causing the new session management function to retrieve session management subscription data.
A method of digital communication, comprising:

receiving, at a session management function of a radio access network, a request to release an existing protocol data unit (PDU) session, the request including an indication about whether the session management function is to send a deregistration request for the existing PDU session to a unified data management function; and

refraining from sending the deregistration request due to receiving the indication.
The method of claim 10, wherein the refraining from sending the deregistration request includes causing an old session management function not to send the deregistration request to the unified data management function.
The method of claim 10, further including:

releasing resources for the existing PDU session; and

sending a response message in response to the request indicating that the request was successfully completed.
The method of claim 12, further including causing the session management function to send a session management function registration request for registering a new session management function.
The method of claim 13, wherein, upon receipt of the session management function registration request, storing a registration context including at least one of PDU session ID, a data network name (DNN) , or a session management function instance ID.
The method of claim 14, wherein the session management function instance ID includes a network function instance ID of a newly selected session management function.
The method of claim 12, further including causing the access and mobility management function to select a new session management function for serving a PDU session.
The method of claim 16, further including causing the access and mobility management function to send, to the new session management function, a message for creating a session management context request.
The method of claim 16, further including causing the new session management function to retrieve session management subscription data.
A computer readable medium product having processor-executable code for implementing one or more of methods as in claims 1-18.
A digital communication apparatus comprising a processor configured to implement a method recited in any one or more of claims 1-18.
A method, apparatus, or system disclosed in the present application.