Title of the invention: Wireless terminal and its method
Technical field
[0001]
This disclosure relates to cellular networks, in particular to the release and establishment of connectivity services between UEs and external data networks.
Background technology
[0002]
5G system (5GS) connects user equipment (UE) to an external data network (Data Network (DN)). In the 5G architecture, the connectivity service between the UE and the DN is supported by Protocol Data Unit (PDU) sessions. A PDU session is an association between a UE and a DN and is used to provide a PDU connectivity service (ie, the exchange of PDUs between the UE and the DN). A PDU session is established between the UE and the User Plane Function (UPF) (i.e., PDU session anchor) to which the DN is connected. From a data transfer perspective, a PDU session is a tunnel (N9 tunnel) within a 5G core network (5GC), a tunnel between 5GC and an access network (AN) (N3 tunnel), And one or more radio bearers.
[0003]
The PDU session is managed by the Session Management Function (SMF). SMF communicates with the UE's Non-Access Stratum (NAS) -SM layer via the network function (NF) service (ie, communication service with the UE) provided by the Access and Mobility Management Function (AMF). Send and receive SM signaling messages (NAS-SM messages, N1 SM messages).
[0004]
AMF terminates one (single) signaling connection (i.e., N1 NAS signalling connection) with the UE. The Single N1 NAS signaling connection is used for both Registration Management and Connection Management (RM / CM) for UEs as well as SM related messages and procedures.
[0005]
The PDU session is established in response to a request from the UE or network. The PDU Session ID is used to identify the PDU session. The PDU Session ID is generated by the UE and is a unique identifier among the PDU Sessions handled by this UE. The PDU Session ID assigned to the newly generated PDU session must not be the same as the ID of any existing (existing) PDU session. The PDU Session ID used in the present specification may mean the value of the PDU Session ID generated for the PDU session.
[0006]
Non-Patent Document 1 (3GPP TS 23.502) and Non-Patent Document 2 (3GPP TS 24.501) specify a PDU session establishment procedure and a PDU session release procedure. More specifically, the procedure for establishing a PDU session is described in, for example, Chapter 4.3.2.2 of Non-Patent Document 1 and Chapter 6.4.1 of Non-Patent Document 2. The PDU session release procedure is described, for example, in Chapter 4.3.4.2 of Non-Patent Document 1 and Chapters 6.3.3 and 6.4.3 of Non-Patent Document 2.
Prior art literature
Non-patent literature
[0007]
Non-Patent Document 1: 3GPP TS 23.502 V16.2.0 (2019-09) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 16)”, September 2019
Non-Patent Document 2: 3GPP TS 24.501 V16.2.0 (2019-09) “3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 (Release) 16) ”, September 2019
Outline of the invention
Problems to be solved by the invention
[0008]
Following the PDU session release procedure initiated by the UE described in Chapter 4.3.4.2 of Non-Patent Document 1, the UE receives a NAS message containing the PDU Session Release Command from the AMF. The PDU Session Release Command is an SM signaling (N1 SM message) sent from the SMF to the UE via the AMF to instruct the UE to release the PDU session. The UE then sends a NAS message containing the PDU Session Release Complete to the AMF in order to acknowledge the PDU Session Release Command. The NAS message includes the PDU Session ID of the PDU session to be released and the N1 SM container (PDU Session Release Complete). The N1 SM container (PDU Session Release Complete) is sent to the SMF via the AMF. PDU Session Release Complete may be referred to as PDU Session Release Ack.
[0009]
After that, SMF implements (invoke) Nsmf_PDUSession_SMContextStatusNotify service operation to notify AMF that the SM context for the PDU session will be released. Nsmf_PDUSession_SMContextStatusNotify is one of the NF services provided by SMF. Nsmf_PDUSession_SMContextStatusNotify is used by the SMF to notify its consumer (e.g., AMF) of the status of the SM context for a PDU session.
[0010]
In response to the Nsmf_PDUSession_SMContextStatusNotify message, AMF releases the UE context (i.e., PDU session level context) associated with the PDU session. The PDU session level context managed by AMF contains the association between SMF information (e.g., SMF ID), PDU Session ID, and Data Network Name (DNN).
[0011]
In addition, the SMF implements a Nudm_UECM_Deregistration service operation (invoke) that includes the Data Network Name (DNN) and PDU Session ID to release the context for the PDU session to be released. Nudm_UECM_Deregistration is one of the NF services provided by Unified Data Management (UDM). The NF Consumer (e.g., SMF) uses the Nudm_UECM_Deregistration service operation to request the UDM to delete the information related to the NF. UDM removes the association between the SMF identity and the associated DNN and PDU Session ID in response to a request from the SMF.
[0012]
That is, according to the PDU session release procedure initiated by the UE described in Chapter 4.3.4.2 of Non-Patent Document 1, the UE sends the PDU Session Release Complete (SM signaling) to the SMF via the AMF and then the SMF. Releases the context (resource) in 5GC related to the PDU session (clears from within 5GC) in cooperation with AMF and UDM.
[0013]
However, with existing procedures, the UE may be able to request the 5GC to establish a new PDU session immediately after sending the PDU Session Release Complete (SM signaling). In addition, the UE may be able to use the PDU Session ID associated with the recently released PDU session for the newly established PDU session. This is because, from the UE's point of view, the PDU Session ID is not considered to be already associated with any existing PDU session.
[0014]
Therefore, before the release of a PDU session within the 5GC (that is, the clearing of the context for the PDU session) is successfully completed, the 5GC will show the same PDU Session ID as that of the PDU session released. It is possible to receive an establishment request from the UE. In this case, 5GC may not be able to correctly distinguish the newly established PDU session from the released PDU session. This is because the PDU Session ID generated (determined) by the UE is used in the management of the PDU session by the SMF and the management of the UE context (PDU Session level context) related to the PDU session by the AMF.
[0015]
For example, an unfavorable scenario including the following steps (1) to (3) can be considered. In step (1), a PDU session release procedure initiated by the UE is performed to release an existing PDU session managed by SMF # 1 and associated with PDU Session ID # 1. In the release procedure, the UE sends a NAS message containing PDU Session ID # 1 and N1 SM container (PDU Session Release Complete) to AMF.
[0016]
In step (2), the UE selects PDU Session ID # 1 to establish a new PDU session immediately after sending the PDU Session Release Complete, and issues a NAS message requesting the establishment of a new PDU session. Send to AMF. The NAS message includes a PDU Session ID # 1, a Request type indicating an "initial request" or an "initial emergency request", and an N1 SM container (PDU Session Establishment Request). AMF, for example, selected SMF # 2 for a new PDU session and Nsmf_PDUSessi Send on_CreateSMContext Request to SMF # 2. The Nsmf_PDUSession_CreateSMContext Request includes PDU Session ID # 1 and N1 SM container (PDU Session Establishment Request). Nsmf_PDUSession_CreateSMContext service operation is one of the NF services provided by SMF. As an NF consumer, AMF uses Nsmf_PDUSession_CreateSMContext to create an AMF-SMF association to support PDU sessions.
[0017]
In step (3), while the procedure for establishing a new PDU session related to step (2) is being performed, SMF # 1 indicates that the SM context for the existing PDU session is released Nsmf_PDUSession_SMContextStatusNotify. Send a message to AMF. In this case, the PDU Session ID of the new PDU session is the same as that of the released PDU session, so for example, the AMF is a created UE context (PDU Session level context) for the new PDU session. ) May be accidentally deleted.
[0018]
As mentioned above, existing PDU session establishment and PDU session release procedures (procedures) may fail if the UE initiates the PDU session establishment procedure before the PDU session release within 5GC is successfully completed. do not have. Specifically, there is a risk of conflict (conflict, collision) between the release of an incomplete PDU session associated with the same PDU Session ID and the establishment of a new PDU session. Such a collision (or a situation in which such a collision occurs) can be referred to as a PDU Session ID duplicated.
[0019]
Note that this problem can occur not only in the case where the UE requests the SMF to release the PDU session (PDU session release procedure started by the UE). Specifically, this problem can also occur if the Policy Control Function (PCF) requires the SMF to release a PDU session. The problem is also when the Access Network (AN) requests the SMF to release the PDU session, in other words, the AN notifies the SMF of the release of resources related to the PDU session, and the SMF releases the PDU session based on the notification. It can also happen in the case of determining. In addition, this problem can occur if the SMF decides to release the PDU session and initiates the release of the PDU session.
[0020]
One of the objectives to be achieved by the embodiments disclosed herein is to avoid conflicts between incomplete PDU session release and new PDU session establishment associated with the same PDU Session ID. To provide equipment, methods, and programs that contribute to. It should be noted that this object is only one of the purposes that the plurality of embodiments disclosed herein seek to achieve. Other objectives or issues and novel features will be apparent from the description or accompanying drawings herein.
Means to solve problems
[0021]
In the first aspect, the AMF node comprises at least one memory and at least one processor coupled to said at least one memory. The at least one processor includes the first SM container in response to receiving a first control message including the first Session Management (SM) container from the Session Management Function (SMF). 1 Non-Access Stratum (NAS) message is configured to be sent to a wireless terminal. The first SM container sends a PDU Session Release Command message sent from the SMF to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Include. The at least one processor can further assign the first PDU Session ID to another PDU session different from the first PDU session after sending the first NAS message to the radio terminal. It is configured to send a second NAS message to indicate that to the wireless terminal.
[0022]
In the second aspect, the method for the AMF node comprises the following steps (a) and (b):
(A) In response to receiving a first control message including the first Session Management (SM) container from the Session Management Function (SMF), the first Non- including the first SM container. Sending an Access Stratum (NAS) message to a wireless terminal, where the first SM container indicates the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes PDU Session Release Command messages sent from the SMF to the wireless terminal;
(B) A second to show that the first PDU Session ID can be assigned to another PDU session different from the first PDU session after the first NAS message is sent to the wireless terminal. Sending the NAS message of 2 to the wireless terminal.
[0023]
In the third aspect, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive a first Non-Access Stratum (NAS) message, including a first Session Management (SM) container, from the Access and Mobility Management Function (AMF). The first SM container is a PDU Session transmitted from the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes Release Command message. The at least one processor further indicates that after receiving the first NAS message, the first PDU Session ID can be assigned to another PDU session different from the first PDU session. The second NAS message is configured to be received from the AMF.
[0024]
In the fourth aspect, the method for the wireless terminal includes the following steps (a) and (b):
(A) Receiving a first Non-Access Stratum (NAS) message comprising a first Session Management (SM) container from the Access and Mobility Management Function (AMF), where the first SM container is said. , Includes a PDU Session Release Command message sent by the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID; as well as
(B) A second NAS message to indicate that after receiving the first NAS message, the first PDU Session ID can be assigned to another PDU session different from the first PDU session. Is received from the AMF.
[0025]
In a fifth aspect, the wireless terminal comprises at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive a first Non-Access Stratum (NAS) message, including a first Session Management (SM) container, from the Access and Mobility Management Function (AMF). The first SM container is a PDU Session Release sent from the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes Command messages. The at least one processor further receives the second NAS message from the AMF after receiving the first NAS message, and the at least one processor receives the second NAS message. The first PDU Session ID can be assigned.
[0026]
In the sixth aspect, the method of the wireless terminal includes the following steps (a) and (b):
(A) Receiving a first Non-Access Stratum (NAS) message comprising a first Session Management (SM) container from the Access and Mobility Management Function (AMF), where the first SM container is said. , Includes a PDU Session Release Command message sent by the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID; and
(B) After receiving the first NAS message, the second NAS message is received from the AMF, and by receiving the second NAS message, the first PDU Session ID can be assigned. matter.
[0027]
In the seventh aspect, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The PDU Session Release Command specifies when the at least one processor receives a first control message from the Access and Mobility Management Function (AMF) that includes a Session Management (SM) container containing a PDU Session Release Command. It is configured so that the PDU Session ID specified by the PDU Session Release Command cannot be assigned or is not permitted to other PDU sessions other than the PDU session. The at least one processor receives the first control message from the Access and Mobility Management Function (AMF) including the Session Management (SM) container including the NAS Notify, so that the NAS Notify can be sent to the other PDU session. Is configured to allow the assignment of the PDU Session ID specified by.
[0028]
In the eighth aspect, the method for the wireless terminal is described in the following steps (a) and (b) includes:
(A) A session other than the PDU session specified by the PDU Session Release Command when the first control message including the Session Management (SM) container including the PDU Session Release Command is received from the Access and Mobility Management Function (AMF). The PDU Session ID specified by the PDU Session Release Command cannot or is not allowed for other PDU sessions;
(B) By receiving the first control message including the Session Management (SM) container including the NAS Notify from the Access and Mobility Management Function (AMF), the PDU designated by the NAS Notify is added to the other PDU session. Session ID assignment is allowed.
[0029]
In a ninth aspect, the AMF node comprises at least one memory and at least one processor coupled to said at least one memory. The at least one processor is associated with an existing first PDU session in which the new PDU Session ID associated with the new Protocol Data Unit (PDU) session requested by the wireless terminal has not been successfully released. It is configured to determine if it is the same as the first PDU Session ID. The at least one processor further avoids conflict between establishing the new PDU session and releasing the first PDU session if the new PDU Session ID is the same as the first PDU Session ID. It is configured to perform the steps to do so.
[0030]
In a tenth aspect, the method for the AMF node comprises the following steps (a) and (b):
(A) The new PDU Session ID associated with the new Protocol Data Unit (PDU) session requested by the wireless terminal is the first associated with the existing first PDU session that has not been successfully released. Determining if it is the same as the PDU Session ID; and
(B) When the new PDU Session ID is the same as the first PDU Session ID, the procedure for avoiding the conflict of establishing the new PDU session and releasing the first PDU session is executed. matter.
[0031]
In the eleventh aspect, the SMF node includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive a first NAS message for establishing a new Protocol Data Unit (PDU) session from a wireless terminal via the Access and Mobility Management Function (AMF). The at least one processor is further associated with a first PDU Session ID associated with an existing first PDU session for which the new PDU Session ID associated with the new PDU session has not been successfully released. If they are the same, a second NAS message indicating refusal to establish the new PDU session is configured to be transmitted to the radio terminal via the AMF.
[0032]
In a twelfth aspect, the method for the SMF node comprises the following steps (a) and (b):
(A) Receiving the first NAS message for establishing a new Protocol Data Unit (PDU) session from the wireless terminal via the Access and Mobility Management Function (AMF); and
(B) When the new PDU Session ID associated with the new PDU session is the same as the first PDU Session ID associated with the existing first PDU session that has not been successfully released. Sending a second NAS message indicating the refusal to establish the new PDU session to the wireless terminal via the AMF.
[0033]
In the thirteenth aspect, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is different from the first PDU Session ID assigned to the first PDU session during the first period associated with the release of the first Protocol Data Unit (PDU) session. Configured to assign a PDU Session ID to a newly established PDU session.
[0034]
In the fourteenth aspect, the method for a wireless terminal comprises the following steps (a) and (b):
(A) A PDU Session ID that is different from the first PDU Session ID assigned to the first PDU session during the first period associated with the release of the first Protocol Data Unit (PDU) session. Assign to a newly established PDU session; and
(B) Initiate the PDU session establishment procedure with the different PDU Session ID.
[0035]
In a fifteenth aspect, the wireless terminal comprises at least one memory and at least one processor coupled to said at least one memory. The at least one processor is configured to assign a PDU Session ID different from the immediately used one or more Protocol Data Unit (PDU) Session IDs to the newly established PDU session.
[0036]
In the sixteenth aspect, the method for the wireless terminal comprises the following steps (a) and (b):
(A) Assigning a newly established PDU Session ID that is different from the one or more Protocol Data Unit (PDU) Session IDs used immediately before; and
(B) Initiate the PDU session establishment procedure with the different PDU Session ID.
[0037]
In the seventeenth aspect, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor has been assigned to the first Protocol Data Unit (PDU) session in at least the first attempt to establish a new PDU session following the release of the first Protocol Data Unit (PDU) session. It is configured to assign a PDU Session ID different from the PDU Session ID to the new PDU session.
[0038]
In the eighteenth aspect, the method for the wireless terminal comprises the following steps (a) and (b):
(A) With the first PDU Session ID assigned to the first PDU session in at least the first attempt to establish a new PDU session after the release of the first Protocol Data Unit (PDU) session. Assigns a different PDU Session ID to the new PDU session;
(B) Initiate the PDU session establishment procedure with the different PDU Session ID.
[0039]
In the nineteenth aspect, when the program is loaded into a computer, it relates to the second, fourth, sixth, eighth, tenth, twelfth, fourteenth, sixteenth, or eighteenth aspect described above. Includes instructions (software code) to make the computer perform the method.
The invention's effect
[0040]
According to the above aspects, there is provided a device, method, and program that contributes to avoiding a conflict (conflict) between the release of an incomplete PDU session associated with the same PDU Session ID and the establishment of a new PDU session. can.
A brief description of the drawing
[0041]
FIG. 1 is a diagram showing a configuration example of a cellular network according to an embodiment.
FIG. 2 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 3 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 4 is a sequence diagram showing an example of the operation of UE and AMF according to the embodiment.
FIG. 5 is a flowchart showing an example of the operation of AMF according to the embodiment.
FIG. 6 is a flowchart showing an example of the operation of AMF according to the embodiment.
FIG. 7 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 8 is a flowchart showing an example of the operation of AMF according to the embodiment.
FIG. 9 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 10 is a flowchart showing an example of the operation of AMF according to the embodiment.
FIG. 11 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 12 is a flowchart showing an example of the operation of AMF according to the embodiment.
FIG. 13 is a sequence diagram showing an example of the operation of UE, AMF, and SMF according to the embodiment.
FIG. 14 is a flowchart showing an example of the operation of the UE according to the embodiment.
FIG. 15 is a flowchart showing an example of the operation of the UE according to the embodiment.
FIG. 16 is a flowchart showing an example of the operation of the UE according to the embodiment.
FIG. 17 is a block diagram showing a configuration example of a UE according to an embodiment.
FIG. 18 is a block diagram showing a configuration example of AMF and SMF according to an embodiment.
Embodiment for carrying out the invention
[0042]
In the following, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary for the sake of clarity of explanation.
[0043]
The plurality of embodiments described below may be implemented independently or in combination as appropriate. These plurality of embodiments have novel features that differ from each other. Therefore, these plurality of embodiments contribute to solving different purposes or problems, and contribute to different effects.
[0044]
The plurality of embodiments shown below will be described mainly for the 3GPP 5th generation mobile communication system (5G system (5GS)). However, these embodiments may be applied to other cellular communication systems that support session (or connection) establishment and release procedures similar to 5GS.
[0045]

FIG. 1 shows a configuration example of a cellular network (i.e., 5GS) according to this embodiment. Each of the elements shown in FIG. 1 is a network function and provides an interface defined by the 3rd Generation Partnership Project (3GPP). Each element (network function) shown in FIG. 1 is, for example, as a network element on dedicated hardware, as a running software instance on dedicated hardware, or on an application platform. It can be implemented as an instantiated virtualization function.
[0046]
The wireless terminal (i.e., UE) 1 uses the 5G connection (connectivity) service to communicate with the external data network (DN) 6. More specifically, UE1 is an access network (i.e., 5GAN).It is connected to 4 and communicates with the external data network (DN) 6 via the User Plane Function (UPF) 5 in the core network (i.e., 5GC). AN4 includes the Next Generation Radio Access Network (NG-RAN) and / or non-3GPP AN. The UPF 5 may include a plurality of interconnected UPFs. UE1 establishes one or more PDU sessions between UE1 and UPF5 (ie, UPF as a PDU session anchor connected to DN6). Although not shown in FIG. 1, the UE 1 may establish multiple PDU sessions with each of the plurality of UPFs (PDU session anchors) 5 in order to access the plurality of DNs 6 simultaneously.
[0047]
AMF2 is one of the network functions in the 5GC Control Plane. AMF2 provides the termination of the RAN Control Plane (CP) interface (i.e., N2 interface). AMF2 terminates one (i.e., N1 NAS signaling connection) with UE1 and provides registration management, connection management, and mobility management. AMF2 provides NF services (services) to NF consumers (e.g. other AMF, SMF, and PCF) on a service-based interface (i.e., Namf interface). The NF service provided by AMF2 includes a communication service (Namf_Communication). The communication service allows an NF consumer (e.g., SMF) to communicate with UE1 or AN4 via AMF2.
[0048]
SMF3 is one of the network functions in the 5GC Control Plane. SMF3 manages PDU sessions. The SMF3 sends and receives SM signaling messages (NAS-SM messages, N1 SM messages) to and from the NAS-SM layer of UE1 via the communication service provided by AMF2. SMF3 provides NF services (services) to NF consumers (e.g. AMF, other SMFs) on a service-based interface (i.e., Nsmf interface). The NF service provided by SMF3 includes a PDU session management service (Nsmf_PDUSession). The NF service allows NF consumers (e.g., AMF) to handle PDU sessions.
[0049]
The configuration example in FIG. 1 shows only typical NFs for convenience of explanation. The cellular network according to this embodiment may include other NFs not shown in FIG. 1, such as UDM, PCF, Authentication Server Function (AUSF), and Network Slice Selection Function (NSSF).
[0050]
Below, the details of the operations of UE1, AMF2, and SMF3 according to this embodiment will be described. FIG. 2 shows an example of an operation relating to the release of the first PDU session associated with PDU Session ID # 1. In the example of FIG. 2, UE1 receives a PDU Session Release Command from SMF3 via AMF2 indicating the release of the first PDU session associated with PDU Session ID # 1 (step 203), followed by the PDU Session. Additional NAS messages (eg, NAS Notify) associated with ID # 1 are further received from AMF2 or via AMF2 from SMF3 (step 205).
[0051]
An additional NAS message (step 205) explicitly or implies to UE1 that the Session Management (SM) context for the first PDU session (PDU Session ID # 1) was successfully released in 5GC. May be notified to. Further or instead, an additional NAS message (step 205) explicitly or implicitly allows UE1 to assign PDU Session ID # 1 to a new PDU session separate from the first PDU session. You may.
[0052]
UE1 may understand that PDU Session ID # 1 can be assigned to a new PDU session different from the first PDU session in response to the additional NAS message (step 205). UE1 sends a new PDU Session ID # 1 in response to the PDU Session Release Command message (step 203) until it receives an additional NAS message (step 205) after sending a PDU Session Release Complete message to SMF3. It may work so that it is not assigned to an established PDU session. In other words, UE1 may operate to assign a PDU Session ID different from PDU Session ID # 1 to the newly established PDU session until at least an additional NAS message (step 205) is received.
[0053]
The steps shown in FIG. 2 will be specifically described. In step 201, UE1 establishes a first PDU session associated with PDU Session ID # 1. Step 201 may be performed according to an existing PDU session establishment procedure (see, eg, Section 4.3.2.2 of Non-Patent Document 1).
[0054]
Steps 202-205 relate to the release of the first PDU session. In step 202, SMF3 sends an N1 SM container containing the PDU Session Release Command to AMF2. The PDU Session Release Command is sent from SMF3 to UE1 to indicate the release of the first PDU session associated with PDU Session ID # 1. Specifically, if PDU session release is initiated by UE1, SMF3 sends an N1 SM container containing the PDU Session Release Command to AMF2 using the Nsmf_PDUSession_UpdateSMContext Response message. Similarly, if PDU session release is triggered by AN4, SMF3 sends an N1 SM container containing the PDU Session Release Command to AMF2 using the Nsmf_PDUSession_UpdateSMContext Response message. On the other hand, if the PDU session release is initiated by SMF3 or PCF, SMF3 sends an N1 SM container containing the PDU Session Release Command to AMF2 using the Namf_Communication_N1N2MessageTransfer message.
[0055]
Next, in step 203, AMF2 sends a NAS message including an N1 SM container including a PDU Session Release Command to UE1 via AN4. Steps 202 and 203 may be similar to the corresponding steps contained in an existing PDU session release procedure (eg, see Section 4.3.4.2 of Non-Patent Document 1).
[0056]
Although not shown in FIG. 2, UE1 responds to the PDU Session Release Command (step 203) by directing a PDU Session Release Complete message to SMF3 prior to receiving an additional NAS message (step 205). You may send it. More specifically, UE1 may send a NAS message to AMF2 containing an N1 SM container containing a PDU Session Release Complete message for SMF3. The PDU Session Release Complete message indicates the acceptance of the release of the PDU session specified by the PDU Session Release Command. The PDU Session Release Complete message may be referred to as the PDU Session Release Ack message.
[0057]
In step 204, SMF3 implements (invoke) Nsmf_PDUSession_SMContextStatusNotify service operation in order to notify AMF2 that the SM context for the first PDU session is released. The Nsmf_PDUSession_SMContextStatusNotify message (step 204) informs AMF2 that the status of the SM context for the first PDU session associated with PDU Session ID # 1 is "released".
[0058]
In response to the Nsmf_PDUSession_SMContextStatusNotify message (step 204), AMF2 releases the UE context (i.e., PDU session level context) associated with the first PDU session. The PDU session level context managed by AMF2 includes, for example, the association between SMF information (e.g., SMF ID), PDU Session ID, and DNN.
[0059]
In step 205, AMF2 sends an additional NAS message (e.g., NAS Notify) to UE1 in response to receiving the Nsmf_PDUSession_SMContextStatusNotify message (step 204). An additional NAS message indicates PDU Session ID # 1. AMF2 sends an additional NAS message (step 205) before, after, or at the same time as releasing the UE context (ie, PDU session level context) associated with the first PDU session. You may.
[0060]
UE1 receives an additional NAS message (step 205) after receiving the NAS message (step 203) including the PDU Session Release Command. As mentioned above, UE1 may also understand that PDU Session ID # 1 can be assigned to a new PDU session separate from the first PDU session in response to an additional NAS message (step 205). good. In other words, UE1 may operate to assign a PDU Session ID different from PDU Session ID # 1 to the newly established PDU session until at least an additional NAS message (step 205) is received. The SMF3 may send an additional NAS message (step 205) to the UE1 at any time. For example, an additional NAS message (step 205) may be sent from SMF3 to UE1 after the first PDU session associated with PDU Session ID # 1 is established as shown in step 201. ..
[0061]
FIG. 3 shows the UE according to this embodiment.A specific example of the PDU session release procedure started by 1 is shown in detail. In step 301, UE1 establishes a first PDU session associated with PDU Session ID # 1. Step 301 may be performed according to an existing PDU session establishment procedure (see, eg, Section 4.3.2.2 of Non-Patent Document 1).
[0062]
Steps 302 to 312 relate to the release of the first PDU session (PDU Session ID # 1). Except for steps 310 and 311, steps 302-309 and 312 may be similar to the corresponding steps contained in an existing PDU session release procedure (eg, see Section 4.3.4.2 of Non-Patent Document 1). .. Steps 304 and 305 correspond to steps 202 and 203 of FIG. 2, and steps 309 and 310 correspond to steps 204 and 205 of FIG.
[0063]
In step 302, UE1 initiates a PDU session release procedure to request the release of the first PDU session associated with PDU Session ID # 1. That is, UE1 transmits a PDU Session Release Request to SMF3 via AMF2. More specifically, UE1 sends a NAS message containing PDU Session ID # 1 and N1 SM container (PDU Session Release Request (PDU Session ID # 1)) to AMF2. In step 303, AMF2 invokes the Nsmf_PDUSession_UpdateSMContext service operation and forwards the N1 SM container to SMF3 corresponding to PDU Session ID # 1.
[0064]
In response to step 303, SMF3 releases the IP address and prefix (Prefix (es)) assigned to the first PDU session and releases the corresponding user plane resource. Then, in step 304, SMF3 responds to AMF2 by Nsmf_PDUSession_UpdateSMContext response. The Nsmf_PDUSession_UpdateSMContext response includes an N1 SM container (PDU Session Release Command (PDU Session ID # 1)). In step 305, AMF2 transmits the N1 SM container (PDU Session Release Command (PDU Session ID # 1)) received from SMF3 to UE1. Specifically, AMF2 sends a NAS message containing PDU Session ID # 1 and N1 SM container to UE1. The NAS message reaches UE1 via AN4.
[0065]
In step 306, UE1 sends a NAS message including PDU Session Release Complete to AMF2 in order to acknowledge the PDU Session Release Command. The NAS message includes the PDU Session ID of the PDU session to be released and the N1 SM container (PDU Session Release Complete). In step 307, AMF2 invokes the Nsmf_PDUSession_UpdateSMContext service operation and forwards the N1 SM container to SMF3 corresponding to PDU Session ID # 1. In step 308, SMF3 responds to AMF2 by Nsmf_PDUSession_UpdateSMContext response.
[0066]
In step 309, SMF3 implements an Nsmf_PDUSession_SMContextStatusNotify service operation (invoke) to notify AMF2 that the SM context for the first PDU session is released. The Nsmf_PDUSession_SMContextStatusNotify message (step 309) informs AMF2 that the status of the SM context for the first PDU session associated with PDU Session ID # 1 is "released".
[0067]
In response to the Nsmf_PDUSession_SMContextStatusNotify message (step 309), AMF2 releases the PDU session level context associated with the first PDU session. In step 310, AMF2 sends an additional NAS message (e.g., NAS Notify) to UE1 in response to receiving the Nsmf_PDUSession_SMContextStatusNotify message (step 309). An additional NAS message indicates PDU Session ID # 1. The AMF2 may send additional NAS messages (step 310) before, after, or at the same time as releasing the PDU session level context associated with the first PDU session. Upon receiving the additional NAS message, UE1 can assign PDU Session ID # 1 to PDU sessions other than the first PDU session.
[0068]
In step 311 the UE1 responds to AMF2 by a NAS message (e.g., NAS Notify Ack). Step 311 may be omitted.
[0069]
In step 312, AMF2 responds to SMF3 by Nsmf_PDUSession_SMContextStatusNotify Ack. In one example, AMF2 may perform step 312 in response to receiving the NAS message in step 311. Instead, AMF2 may perform step 312 regardless of the reception of the NAS message in step 311. For example, AMF2 may perform step 312 before step 311.
[0070]
The procedure shown in FIGS. 2 and 3 may be modified as follows, for example. The SMF3 may send the N1 SM container addressed to UE1 to AMF2 using the Namf_Communication_N1N2MessageTransfer message before or after the Nsmf_PDUSession_SMContextStatusNotify service operation (step 204, step 309). Then, AMF2 may send an additional NAS message (step 205, step 310) including the N1 SM container to UE1. The N1 SM container may include, for example, a new SM signaling message to notify UE1 that the SM context for one PDU session will be released. That is, the transmission of the additional NAS message (step 205, step 310) by AMF2 may be triggered by a control message different from Nsmf_PDUSession_SMContextStatusNotify.
[0071]
As can be understood from the above description, in the present embodiment, the AMF2 (or SMF3) is an additional NAS message (eg, step 205) in addition to the NAS message including the PDU Session Release Command in the PDU session release procedure. , Step 310) is transmitted to UE1. This can, for example, allow UE1 not to assign PDU Session ID # 1 to a newly established PDU session until at least additional NAS messages (e.g., step 205, step 310) have been received. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0072]

The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG. UE1 may inform AMF2 that it supports the PDU session release procedure described in the first embodiment (hereinafter, also referred to as an improved PDU session release procedure). For example, UE1 may send capability information to AMF2 indicating that UE1 has the ability to handle the improved PDU session release procedure. AMF2 may decide whether to utilize the improved PDU session release procedure for UE1 depending on whether the capability information has been received from UE1. Further, the AMF2 may inform the UE1 to apply the improved PDU session release procedure depending on whether or not the capability information has been received from the UE1. It should be noted that this improved PDU session release procedure includes a procedure for transmitting an additional NAS message (eg, step 205 or step 310 in the first embodiment) to the UE 1 in the normal PDU session release procedure. You may.
[0073]
More specifically, as shown in FIG. 4, UE1 may send the capability information (e.g., “Release with Notify Handling Capability”) to AMF2 in the procedure for registering UE1 in 5GS. UE1 may include the capability information in the Registration Request message (step 401). The capability information may be added to an existing information element (e.g., “5GMM capability” information element). In addition, in the UE1 registration procedure, AMF2 may inform UE1 of the use of the improved PDU session release procedure. For example, AMF2 may include an information element in the Registration Accept message indicating the use of the improved PDU session release procedure. The name of the information element may be, for example, “Release with Notify Handling Capability”, “Release with Notify Handling Adapted”, or “Duplicated PDU Session ID detection capability supported”. Existing information elements (e.g., “5GS network feature support” information element) may be used by AMF2 to indicate to UE1 the use of the (improved) PDU session release procedure. AMF2 is expected to be connected to the capabilities of SMF3 connected to UE1 and to UE1 when deciding whether to set the information element indicating the use of the improved PDU session release procedure in the Registration Accept message. One or both of the capabilities of SMF3 may be considered.
[0074]
In some implementations, UE1 receives information from AMF2 via a Registration Accept message indicating the use of the (improved) PDU session release procedure, the N1 SM container (PDU Session Release Command (PDU Session ID)). Even if # 1)) is received, PDU Session ID # 1 cannot be assigned or permitted to PDU sessions other than the first PDU session.
[0075]
This implementation form According to the procedure, 5GS (AMF2) can provide connection services to UEs that support and do not support the improved PDU session release procedure. The procedure may be used to inform AMF2 that it supports the improved PDU session release procedure according to the embodiments described below.
[0076]

This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG. FIG. 5 is a flowchart showing an example of the operation of AMF2 according to the present embodiment. In step 501, AMF2 receives a PDU Session Establishment Request message from UE1. Specifically, AMF2 receives a NAS message from UE1 including a PDU Session ID, a Request type indicating "initial request" or "initial emergency request", and an N1 SM container (PDU Session Establishment Request).
[0077]
In step 502, AMF2 determines whether the new PDU Session ID associated with the new PDU session requested by UE1 is the same as the PDU Session ID of the existing PDU session that has not been successfully released. AMF2 may execute the determination when the Request type included in the NAS message from UE1 indicates "initial request" or "initial emergency request". More specifically, AMF2 indicates that the Request type included in the NAS message from UE1 indicates "initial request" or "initial emergency request", and is valid associated with the PDU Session ID included in the NAS message. If AMF2 holds a new PDU session level context, AMF2 may determine that the new PDU Session ID is the same as that of an existing PDU session.
[0078]
In step 503, if the new PDU Session ID is the same as that of the existing PDU session, AMF2 performs a procedure for avoiding a conflict between establishing the new PDU session and releasing the existing PDU session. There are multiple possible solutions for procedures to avoid conflicts. In this embodiment, one or several solutions will be described. Other solutions are described in subsequent embodiments.
[0079]
In one example, AMF2 may perform the procedure shown in FIG. Steps 601 and 602 are similar to steps 501 and 502 in FIG. In step 603, if the new PDU Session ID is the same as that of the existing PDU session, AMF2 suspends the establishment of the new PDU session until the release of the existing PDU session is completed. More specifically, AMF2 suppresses sending NAS messages (ie, PDU Session Establishment Request message) for establishing a new PDU session to SMF3 until the release of the existing PDU session is completed. May be good.
[0080] [0080]
FIG. 7 shows in detail a specific example of the PDU session release procedure started by UE1 according to the present embodiment. Steps 701 to 706 are the same as steps 301 to 306 in FIG. That is, in step 701, UE1 establishes a first PDU session associated with PDU Session ID # 1. Step 301 may be performed according to an existing PDU session establishment procedure (see, eg, Section 4.3.2.2 of Non-Patent Document 1). Steps 702-706 relate to the release of the first PDU session (PDU Session ID # 1). Steps 702-706 may be similar to the corresponding steps contained in an existing PDU session release procedure (see, eg, Section 4.3.4.2 of Non-Patent Document 1).
[0081]
In step 707, AMF2 receives the NAS message from UE1. The NAS message includes a PDU Session ID # 1, a Request type indicating an "initial request" or an "initial emergency request", and an N1 SM container (PDU Session Establishment Request). The NAS message is received by AMF2 prior to the completion of the step (step 708) for releasing (erasing) the SM context for the first PDU session within 5GC. The NAS message may be received before the start of step 708, or may be received while step 708 is taking place. Step 708 includes at least an Nsmf_PDUSession_SMContextStatusNotify service operation (similar to step 309 in FIG. 3) that notifies AMF2 that the SM context for the first PDU session is released. Step 708 may further include transmission of an N1 SM container (PDU Session Release Complete (PDU Session ID # 1)) from AMF2 to SMF3 (similar to step 307 in FIG. 3). Step 708 may further include sending an Nsmf_PDUSession_SMContextStatusNotify Ack message from AMF2 to SMF3 (similar to step 312 in FIG. 3).
[0082]
In step 709, AMF2 sends the suspended (deferred) N1 SM container (PDU Session Establishment Request) to SMF3. Specifically, AMF2 sends an Nsmf_PDUSession_CreateSMContext Request that includes an N1 SM container (PDU Session Establishment Request). The AMF2 may select an SMF different from the SMF3 that managed the released first PDU session, and send an N1 SM container (PDU Session Establishment Request) to the selected SMF.
[0083]
Note that the operation of AMF2 according to this embodiment can be performed other than the PDU session release procedure (e.g., FIG. 7) started by UE1. Specifically, the operation of AMF2 according to the present embodiment can be applied to the PDU session release triggered by AN4, the PDU session release initiated by SMF3, and the PDU session release initiated by PCF. ..
[0084]
The procedure described in the second embodiment may be used to inform AMF2 that UE1 supports the PDU session release procedure described in this embodiment.
[0085]
As can be understood from the above description, in this embodiment, AMF2 responds to the determination that the same PDU Session ID is assigned to both the new PDU session and the existing PDU session. Suspend the establishment of a new PDU session until the release of the PDU session is complete. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0086]

This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0087]
FIG. 8 is a flowchart showing an example of the operation of AMF2 according to the present embodiment. Steps 801 and 802 are similar to steps 501 and 502 in FIG. In step 803, if the new PDU Session ID is the same as that of the existing PDU session, AMF2 indicates refusal to establish a new PDU session without sending a PDU Session Establishment Request message to any SMF. Respond to UE1 with a NAS message.
[0088]
Specifically, AMF2 may generate a PDU Session Establishment Reject message and send it to UE1. The PDU Session Establishment Reject message may indicate a new cause (e.g., 5GSM Cause) indicating that the PDU session establishment is temporarily rejected, and a backoff timer value. The new 5GSM Cause may be defined, for example, as “Temporarily Reject”. The backoff timer value is applied to a new timer running in UE1. Alternatively, the backoff timer value may be applied to an existing timer (e.g., T3580). When UE1 receives a PDU Session Establishment Reject message containing 5GSM Cause: “Temporarily Reject” and a backoff timer value, it starts a timer (new or existing) with the backoff timer value set and of the timer. The transmission of a new PDU Session Establishment Request may be suppressed until the expiration date. In other words, UE1 may transmit a new PDU Session Establishment Request (or retransmit the once rejected PDU Session Establishment Request) when the backoff timer value transmitted from AMF2 expires.
[0089]
If the PDU Session Establishment Reject message sent by AMF2 contains a new 5GSM Cause (eg, “Temporarily Reject”) but no backoff timer value, UE1 will see the data configured inside UE1 (UE Local). You may set the backoff timer value based on configuration) to the (new or existing) timer and start it. Then, UE1 may transmit a new PDU Session Establishment Request (or retransmit the once rejected PDU Session Establishment Request) when the timer expires. The backoff timer value based on the data (UE Local configuration) configured inside the UE 1 may be, for example, a few seconds, specifically 2 to 3 seconds.
[0090]
If the UE1 receives a PDU Session Establishment Reject message that does not include the backoff timer value while the timer (eg, T3580) related to message retransmission is already operating in the UE1, the UE1 stops the timer and sets the UE1. Internally configured data (UE Local configurat The backoff timer value based on ion) may be set in the timer and the timer may be restarted. Instead, if UE1 receives a PDU Session Establishment Reject message that does not include the backoff timer value while the timer for message retransmission (eg, T3580) is already running in UE1, the timer is set. It may be stopped, the backoff timer value based on the data (UE Local configuration) configured inside UE1 may be set to a timer different from the timer related to message retransmission, and the other timer may be started.
[0091]
FIG. 9 shows in detail a specific example of the PDU session release procedure started by UE1 according to the present embodiment. Steps 901 to 907 are the same as steps 701 to 707 of FIG. The NAS message (PDU Session Establishment Request) of step 907 is received by AMF2 prior to the completion of step (step 909) for releasing (clearing) the SM context for the first PDU session within 5GC. The NAS message may be received before the start of step 909, or may be received while step 909 is taking place. Similar to step 708 of FIG. 7, step 909 includes at least an Nsmf_PDUSession_SMContextStatusNotify service operation (similar to step 309 of FIG. 3) notifying AMF2 that the SM context for the first PDU session is released. Step 909 may further include transmission of an N1 SM container (PDU Session Release Complete (PDU Session ID # 1)) from AMF2 to SMF3 (similar to step 307 in FIG. 3). Step 909 may further include sending an Nsmf_PDUSession_SMContextStatusNotify Ack message from AMF2 to SMF3 (similar to step 312 in FIG. 3).
[0092]
In step 908, AMF2 responds to UE1 with a NAS message indicating refusal to establish a new PDU session without sending a PDU Session Establishment Request message to any SMF. As mentioned above, AMF2 may generate a PDU Session Establishment Reject message and send it to UE1. The PDU Session Establishment Reject message may include 5GSM Cause: “Temporarily Reject” and a backoff timer value. The NAS message (e.g., PDU Session Establishment Reject message) may be transmitted before the start of step 909, or may be transmitted while step 909 is being performed.
[0093]
In some implementations, AMF2 provides information (eg, “5GS network feature support” information element) in the Registration Accept message indicating the use of the improved PDU session release procedure in UE1's Registration Procedure. It may be sent to UE1. Then, AMF2 may generate a PDU Session Establishment Reject message and send it to UE1 when the information indicating the use of the improved PDU session release procedure has been transmitted to UE1 in the location registration process. In contrast, AMF2 discards the PDU Session Establishment Request message received in step 907 if it has not sent information to UE1 in the location registration process indicating the use of the improved PDU session release procedure. May be good.
[0094]
Note that the operation of AMF2 according to this embodiment can be performed other than the PDU session release procedure (e.g., FIG. 9) started by UE1. Specifically, the operation of AMF2 according to the present embodiment can be applied to the PDU session release triggered by AN4, the PDU session release initiated by SMF3, and the PDU session release initiated by PCF. ..
[0095]
The procedure described in the second embodiment may be used to inform AMF2 that UE1 supports the PDU session release procedure described in this embodiment.
[0096]
As can be understood from the above description, in this embodiment, AMF2 determines that the same PDU Session ID is assigned to both the new PDU session and the existing PDU session. Reject the establishment of a PDU session. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0097]

This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0098]
FIG. 10 is a flowchart showing an example of the operation of AMF2 according to the present embodiment. Steps 1001 and 1002 are similar to steps 501 and 502 in FIG. In step 1003, AMF2 sends a PDU Session Establishment Request message to the selected SMF3 in response to determining that the same PDU Session ID has been assigned to both the new PDU session and the existing PDU session. At that time, the SMF3 is notified of the collision of the PDU Session ID. For example, AMF2 is selected for the N1 SM container (PDU Session Establishment Request) with an indication (eg, “PDU Session ID Conflict” or “Duplicated PDU Session ID in AMF”) indicating a PDU Session ID conflict. You may send it to SMF3. The selected SMF3 may be the same as or different from the SMF that manages the existing PDU session.
[0099]
If the selected SMF3 receives a display indicating a PDU Session ID conflict, it may generate a PDU Session Establishment Reject message to reject the establishment of a new PDU session and send it to UE1. The PDU Session Establishment Reject message may indicate a new cause (e.g., 5GSM Cause) indicating that the PDU session establishment is temporarily rejected, and a backoff timer value. The new 5GSM Cause may be defined, for example, as “Temporarily Reject”. The backoff timer value is applied to a new timer running in UE1. Alternatively, the backoff timer value may be applied to an existing timer (e.g., T3580). When UE1 receives a PDU Session Establishment Reject message containing 5GSM Cause: “Temporarily Reject” and a backoff timer value, it starts a timer (new or existing) with the backoff timer value set and of the timer. The transmission of a new PDU Session Establishment Request may be suppressed until the expiration date. In other words, UE1 may send a new PDU Session Establishment Request (or retransmit a once rejected PDU Session Establishment Request) upon expiration of the backoff timer value sent from the selected SMF3.
[0100]
If the PDU Session Establishment Reject message sent by AMF2 contains a new 5GSM Cause (eg, “Temporarily Reject”) but no backoff timer value, UE1 will see the data configured inside UE1 (UE Local). You may set the backoff timer value based on configuration) to the (new or existing) timer and start it. Then, UE1 may transmit a new PDU Session Establishment Request (or retransmit the once rejected PDU Session Establishment Request) when the timer expires. The backoff timer value based on the data (UE Local configuration) configured inside the UE 1 may be, for example, a few seconds, specifically 2 to 3 seconds.
[0101]
If the UE1 receives a PDU Session Establishment Reject message that does not include the backoff timer value while the timer (eg, T3580) related to message retransmission is already operating in the UE1, the UE1 stops the timer and sets the UE1. A backoff timer value based on the internally configured data (UE Local configuration) may be set in the timer, and the timer may be restarted. Instead, if UE1 receives a PDU Session Establishment Reject message that does not include the backoff timer value while the timer for message retransmission (eg, T3580) is already running in UE1, the timer is set. It may be stopped, the backoff timer value based on the data (UE Local configuration) configured inside UE1 may be set to a timer different from the timer related to message retransmission, and the other timer may be started.
[0102]
FIG. 11 shows in detail a specific example of the PDU session release procedure started by UE1 according to the present embodiment. Steps 1101 to 1107 are the same as steps 701 to 707 in FIG. In the example of FIG. 11, the first PDU session is managed by SMF3A.
[0103]
The NAS message (PDU Session Establishment Request) of step 1107 is received by AMF2 before the completion of the step (step 1111) for releasing (erasing) the SM context regarding the first PDU session in 5GC. The NAS message may be received before the start of step 1111 or may be received while step 1111 is taking place. Similar to step 708 of FIG. 7, step 1111 includes at least an Nsmf_PDUSession_SMContextStatusNotify service operation (similar to step 309 of FIG. 3) notifying AMF2 that the SM context for the first PDU session is released. Step 1111 may further include transmission of an N1 SM container (PDU Session Release Complete (PDU Session ID # 1)) from AMF2 to SMF3A (similar to step 307 in FIG. 3). Step 1111 , Nsmf_PDUSession_SMContextStatusNotify Ack message transmission from AMF2 to SMF3A (similar to step 312 in FIG. 3) may be further included.
[0104]
In step 1108, AMF2 selects an SMF and sends an Nsmf_PDUSession_CreateSMContext Request message to the selected SMF (SMF3B, which did not manage the existing PDU session in FIG. 11). The message contains the PDU Session ID # 1 and N1 SM containers (PDU Session Establishment Request) and indicates a PDU Session ID conflict (eg, “PDU Session ID Conflict” or “Duplicated PDU Session ID in AMF”. ) Is further included.
[0105]
In some implementations, AMF2 provides information (eg, “5GS network feature support” information element) in the Registration Accept message indicating the use of the improved PDU session release procedure in UE1's Registration Procedure. It may be sent to UE1. Then, AMF2 may send an Nsmf_PDUSession_CreateSMContext Request message to the selected SMF (SMF3B in FIG. 11) when information indicating the use of the improved PDU session release procedure has been sent to UE1 in the location registration process. .. In contrast, AMF2 discards the PDU Session Establishment Request message received in step 1107 if it has not sent information to UE1 in the location registration process indicating the use of the improved PDU session release procedure. May be good.
[0106]
In step 1109, SMF3B responds to UE1 with a NAS message indicating refusal to establish a new PDU session. SMF3 may generate a PDU Session Establishment Reject message and send it to UE1. The PDU Session Establishment Reject message may include 5GSM Cause: “Temporarily Reject” and a backoff timer value. The NAS message (e.g., PDU Session Establishment Reject message) may be transmitted before the start of step 1111 or may be transmitted while step 1111 is being performed. The Nsmf_PDUSession_CreateSMContext Response message sent from SMF3 to AMF2 includes an N1 SM container (PDU Session Establishment Reject). The message may further include a display indicating a PDU Session ID conflict (e.g., “PDU Session ID Conflict”, or “Duplicated PDU Session ID in AMF”).
[0107]
AMF2 may select SMF3A, which manages an existing PDU session, instead of SMF3B in step 1108. In this case, AMF2 may send an Nsmf_PDUSession_CreateSMContext Request message to SMF3A, and SMF3A may execute the process according to step 1109.
[0108]
Note that the operation of AMF2 according to this embodiment can be performed other than the PDU session release procedure (e.g., FIG. 11) started by UE1. Specifically, the operation of AMF2 according to the present embodiment can be applied to the PDU session release triggered by AN4, the PDU session release initiated by SMF3, and the PDU session release initiated by PCF. ..
[0109]
The procedure described in the second embodiment may be used to inform AMF2 that UE1 supports the PDU session release procedure described in this embodiment.
[0110]
As can be understood from the above description, in this embodiment, AMF2 responds to the determination that the same PDU Session ID is assigned to both the new PDU session and the existing PDU session. Notify SMF3 (eg, SMF3B) of duplicate IDs. This can, for example, allow SMF3 to refuse to establish a new PDU session. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0111]

This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0112]
FIG. 12 is a flowchart showing an example of the operation of AMF2 according to the present embodiment. Steps 1201 and 1202 are similar to steps 501 and 502 in FIG. In step 1203, if the new PDU Session ID is the same as that of the existing PDU session, AMF2 discards the PDU Session Establishment Request message without sending it to any SMF.
[0113]
In this case, UE1 uses the existing timer (i.e., T3580) to retransmit the PDU Session Establishment Request message. UE1 starts timer T3580 in response to sending the first PDU Session Establishment Request message. When the timer T3580 expires, UE1 resends the PDU Session Establishment Request message to AMF2. The timer value of the timer T3580 specified in the current 3GPP specifications is 16 seconds.
[0114]
FIG. 13 shows in detail a specific example of the PDU session release procedure started by UE1 according to the present embodiment. Steps 1301 to 1307 are the same as steps 701 to 707 in FIG. The NAS message (PDU Session Establishment Request) of step 1307 is received by AMF2 prior to the completion of step (step 1309) for releasing (clearing) the SM context for the first PDU session within 5GC. The NAS message may be received before the start of step 1309 or may be received while step 1309 is in progress. Similar to step 708 of FIG. 7, step 1309 includes at least an Nsmf_PDUSession_SMContextStatusNotify service operation (similar to step 309 of FIG. 3) notifying AMF2 that the SM context for the first PDU session is released. Step 1309 may further include transmission of an N1 SM container (PDU Session Release Complete (PDU Session ID # 1)) from AMF2 to SMF3 (similar to step 307 in FIG. 3). Step 1309 may further include sending an Nsmf_PDUSession_SMContextStatusNotify Ack message from AMF2 to SMF3 (similar to step 312 in FIG. 3).
[0115]
In step 1308, AMF2 discards the PDU Session Establishment Request message in AMF2 without sending it to any SMF.
[0116]
Note that the operation of AMF2 according to this embodiment can be performed other than the PDU session release procedure (e.g., FIG. 13) started by UE1. Specifically, the operation of AMF2 according to the present embodiment can be applied to the PDU session release triggered by AN4, the PDU session release initiated by SMF3, and the PDU session release initiated by PCF. ..
[0117]
The procedure described in the second embodiment may be used to inform AMF2 that UE1 supports the PDU session release procedure described in this embodiment.
[0118]
As can be understood from the above description, in this embodiment, AMF2 responds to the determination that the same PDU Session ID is assigned to both the new PDU session and the existing PDU session. Discard the Establishment Request message. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0119]
<7th Embodiment>
This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0120]
FIG. 14 is a flowchart showing an example of the operation of UE1 according to the present embodiment. In step 1401, UE1 newly establishes a PDU Session ID that is different from the first PDU Session ID assigned to the first PDU session during the predetermined period associated with the release of the first PDU session. Assign to a PDU session. In step 1402, UE1 initiates the PDU session establishment procedure using the PDU Session ID determined in step 1401.
[0121]
The above-mentioned predetermined period may be specified in the 3GPP specifications. Further or instead, the UE 1 may configure the above-mentioned predetermined period based on the data (UE Local configuration) configured inside the UE 1. Further or instead, AMF2 or SMF3 may set the above-mentioned predetermined period to UE1. The predetermined period described above may be, for example, a few seconds, specifically 2-3 seconds.
[0122]
If the timer (eg, T3580) related to message retransmission is already operating in UE1, UE1 stops the timer and sets the timer value based on the data (UE Local configuration) configured inside UE1. It may be set to a timer and the timer may be restarted. Instead, the UE1 stops the timer (eg, T3580) related to message retransmission in the UE1 when the timer (eg, T3580) is already operating, and is based on the data (UE Local configuration) configured inside the UE1. The timer value may be set to a timer different from the timer related to message retransmission, and the other timer may be started.
[0123]
In some implementations, UE1 received a PDU Session Release Command message sent from SMF3 to UE1 to indicate the release of the first PDU session.In response to this, it may operate so that the first PDU Session ID is not assigned to the newly established PDU session for a predetermined period of time.
[0124]
In another implementation, UE1 renews the first PDU Session ID for a given period of time in response to releasing the first PDU session in UE1 based on receiving a PDU Session Release Command message from SMF3. It may operate so that it is not assigned to the PDU session established in.
[0125]
In other implementations, UE1 has a new first PDU Session ID for a given period of time in response to sending a PDU Session Release Complete message to approve (accept) the PDU Session Release Command message from SMF3. It may work so that it is not assigned to an established PDU session.
[0126]
In other implementations, UE1 starts the timer in response to the release of the first PDU session and operates so that the first PDU Session ID is not assigned to the newly established PDU session until the timer expires. May be good.
[0127]
As can be understood from the above description, in the present embodiment, UE1 does not assign the PDU Session ID of the released PDU session to the new PDU session for a predetermined period. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0128]

This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0129]
FIG. 15 is a flowchart showing an example of the operation of UE1 according to the present embodiment. In step 1501, UE1 assigns a newly established PDU Session ID that is different from the one or more PDU Session IDs used immediately before. In step 1502, UE1 starts the PDU session establishment procedure using the PDU Session ID determined in step 1501.
[0130]
In some implementations, UE1 may change the value of the PDU Session ID each time a new PDU session is established. More specifically, UE1 may have a plurality of candidate values ​​for the PDU Session ID and sequentially increment the value of the PDU Session ID assigned to the new PDU session. If the number of multiple candidate values ​​for the PDU Session ID is sufficient, UE1 may assign a newly established PDU Session ID that is different from the one or more previously used PDU Session IDs. can.
[0131]
According to this embodiment, it is possible to prevent the PDU Session ID of the released PDU session from being immediately used for a new PDU session. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0132]
<9th embodiment>
This embodiment provides another solution for avoiding conflicts between establishing a new PDU session and releasing an existing PDU session. The configuration example of the cellular network according to the present embodiment may be the same as the example shown in FIG.
[0133]
FIG. 16 is a flowchart showing an example of the operation of UE1 according to the present embodiment. In step 1601, UE1 is different from the first PDU Session ID assigned to the first PDU session in at least the first attempt to establish a new PDU session after the release of the first PDU session. Assign the PDU Session ID to a new PDU session. In step 1602, UE1 initiates the PDU session establishment procedure using the PDU Session ID determined in step 1601.
[0134]
In some implementations, UE1 is at least in the first attempt to establish a new PDU session after receiving a PDU Session Release Command message sent from SMF3 to UE1 to indicate the release of the first PDU session. , Assign a PDU Session ID different from the first PDU Session ID assigned to the first PDU session to the new PDU session.
[0135]
In other implementations, UE1 is at least the first to establish a new PDU session after releasing the first PDU session in UE1 based on the reception of the PDU Session Release Command message for the first PDU session from SMF3. In the trial, a PDU Session ID different from the first PDU Session ID assigned to the first PDU session is assigned to the new PDU session.
[0136]
In other implementations, UE1 is assigned to the first PDU session in at least the first attempt to establish a new PDU session after UE1 sends a PDU Session Release Complete message for the first PDU session. Assign a PDU Session ID different from the first PDU Session ID to the new PDU session.
[0137]
According to this embodiment, it is possible to prevent the PDU Session ID of the released PDU session from being immediately used for a new PDU session. Therefore, the present embodiment avoids a conflict (conflict, conflict, collision, or PDU Session ID duplicated) between an incomplete PDU session release associated with the same PDU Session ID and a new PDU session establishment. Can contribute.
[0138]
Subsequently, in the following, configuration examples of UE1, AMF2, and SMF3 according to the above-mentioned plurality of embodiments will be described. FIG. 17 is a block diagram showing a configuration example of UE1. Radio Frequency (RF) transceiver 1701 performs analog RF signal processing to communicate with NG-RAN nodes. The RF transceiver 1701 may include a plurality of transceivers. The analog RF signal processing performed by the RF transceiver 1701 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1701 is coupled with the antenna array 1702 and the baseband processor 1703. The RF transceiver 1701 receives the modulation symbol data (or OFDM symbol data) from the baseband processor 1703, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1702. Further, the RF transceiver 1701 generates a baseband reception signal based on the received RF signal received by the antenna array 1702, and supplies the baseband reception signal to the baseband processor 1703. The RF transceiver 1701 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, a plurality of phase shifters and a plurality of power amplifiers.
[0139]
Baseband processor 1703 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / restoration, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, and (d) transmission path coding / decoding. , (E) Modulation (symbol mapping) / demodulation, and (f) Generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). On the other hand, the control plane processing includes layer 1 (eg, transmission power control), layer 2 (eg, radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (eg, attach, mobility, and call management). Includes communication management (signaling regarding).
[0140]
For example, digital baseband signal processing by the baseband processor 1703 includes the Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and Physical. (PHY) layer signal processing may be included. The control plane processing by the baseband processor 1703 may also include processing of the Non-Access Stratum (NAS) protocol, Radio Resource Control (RRC) protocol, and MAC Control Elements (CEs).
[0141]
The baseband processor 1703 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.
[0142]
The baseband processor 1703 includes a modem processor (eg, Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (eg, Central Processing Unit (CPU) or Micro Processing Unit (eg, Central Processing Unit (CPU)) that performs control plane processing. MPU)) may be included. In this case, the protocol stack processor that performs the control plane processing may be shared with the application processor 1704 described later.
[0143]
The application processor 1704 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1704 may include a plurality of processors (a plurality of processor cores). The application processor 1704 is a system software program (Operating System (OS)) read from memory 1706 or a memory (not shown) and various application programs (eg, call application, web browser, mailer, camera operation application, music playback). By executing the application), various functions of UE1 are realized.
[0144]
In some implementations, the baseband processor 1703 and the application processor 1704 may be integrated on one chip, as shown by the dashed line (1705) in FIG. In other words, the baseband processor 1703 and application processor 1704 may be implemented as one System on Chip (SoC) device 1705. SoC devices are sometimes referred to as system Large Scale Integration (LSI) or chipsets.
[0145]
Memory 1 Reference numeral 706 is a volatile memory, a non-volatile memory, or a combination thereof. The memory 1706 may include a plurality of physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. Non-volatile memory can be masked Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, the memory 1706 may include an external memory device accessible from the baseband processor 1703, the application processor 1704, and the SoC 1705. The memory 1706 may include an internal memory device integrated within the baseband processor 1703, the application processor 1704, or the SoC 1705. Further, the memory 1706 may include the memory in the Universal Integrated Circuit Card (UICC).
[0146]
The memory 1706 may store one or more software modules (computer programs) 1707 that include instructions and data for performing processing by UE1 described in the plurality of embodiments described above. In some implementations, the baseband processor 1703 or application processor 1704 is configured to read the software module 1707 from memory 1706 and execute it to perform the processing of UE1 described with reference to the drawings in the above embodiments. May be done.
[0147]
It should be noted that the control plane processing and operation performed by UE1 described in the above-described embodiment is performed by other elements other than the RF transceiver 1701 and the antenna array 1702, that is, at least one of the baseband processor 1703 and the application processor 1704 and the software module 1707. It can be realized by the memory 1706 that stores the above.
[0148]
FIG. 18 shows a configuration example of AMF2. SMF3 may also be configured as shown in FIG. Referring to FIG. 18, AMF2 includes a network interface 1801, a processor 1802, and a memory 1803. Network interface 1801 is used, for example, to communicate with RAN nodes and to communicate with other network functions (NFs) or nodes within 5GC. Other NFs or nodes within the 5GC include, for example, UDM, SMF, and PCF. The network interface 1801 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.
[0149]
The processor 1802 may be, for example, a microprocessor, a Micro Processing Unit (MPU), or a Central Processing Unit (CPU). Processor 1802 may include a plurality of processors.
[0150]
Memory 1803 is composed of a volatile memory and a non-volatile memory. Memory 1803 may include a plurality of physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. Non-volatile memory can be masked Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. Memory 1803 may include storage located away from processor 1802. In this case, processor 1802 may access memory 1803 via network interface 1801 or an I / O interface (not shown).
[0151]
The memory 1803 may store one or more software modules (computer programs) 1804 including instruction groups and data for performing processing by AMF2 described in the plurality of embodiments described above. In some implementations, processor 1802 may be configured to read the software module 1804 from memory 1803 and execute it to perform the processing of AMF2 described in the embodiments described above.
[0152]
Furthermore, the above-described embodiment is merely an example relating to the application of the technical idea obtained by the inventor of the present invention. That is, the technical idea is not limited to the above-described embodiment, and various changes can be made to them.
[0153]
For example, some or all of the above embodiments may be described as in the following appendix, but are not limited to the following.
[0154]
(Appendix A1)
Access and Mobility Management Function (AMF) node,
At least one memory and
With at least one processor coupled to the at least one memory,
Equipped with
The at least one processor includes the first SM container in response to receiving a first control message including the first Session Management (SM) container from the Session Management Function (SMF). It is configured to send 1 Non-Access Stratum (NAS) message to a wireless terminal.
The first SM container sends a PDU Session Release Command message sent from the SMF to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Including,
The at least one processor can assign the first PDU Session ID to another PDU session different from the first PDU session after sending the first NAS message to the wireless terminal. A second NAS message to indicate is configured to be sent to the wireless terminal.
AMF node.
(Appendix A2)
The at least one processor responds to receiving a second control message from the SMF notifying the AMF node that the Session Management (SM) context for the first PDU session is released. , Configured to send the second NAS message to the wireless terminal,
The AMF node described in Appendix A1.
(Appendix A3)
The at least one processor is configured to release the PDU session level context relating to the first PDU session and managed by the AMF node in response to receiving the second control message. ,
The AMF node described in Appendix A2.
(Appendix A4)
The PDU session level context comprises associating the first PDU Session ID with SMF information indicating the SMF.
The AMF node described in Appendix A2.
(Appendix A5)
The at least one processor includes a second SM container after the transmission of the first NAS message to the radio terminal and before the reception of the second control message from the SMF. It is configured to receive NAS messages from the wireless terminal.
The second SM container contains a PDU Session Release Complete message transmitted from the wireless terminal to the SMF in order to respond to the PDU Session Release Command message.
The at least one processor is configured to send the second SM container to the SMF.
The AMF node according to any one of Supplementary A2 to A4.
(Appendix A6)
The at least one processor is configured to transmit the second NAS message to the wireless terminal in response to receiving a third control message including the third SM container from the SMF.
The second NAS message includes the third SM container.
The AMF node described in Appendix A1.
(Appendix A7)
The third SM container contains a message sent from the SMF to the radio terminal to notify the radio terminal that the Session Management (SM) context for the first PDU session is released. do,
The AMF node described in Appendix A6.
(Appendix A8)
The second NAS message notifies the wireless terminal that the SM context for the first PDU session has been successfully released in the core network.
The AMF node according to any one of Supplementary A1 to A7.
(Appendix A9)
The second NAS message allows the wireless terminal to assign the first PDU Session ID to a new PDU session different from the first PDU session.
The AMF node according to any one of Supplementary A1 to A8.
(Appendix A10)
The at least one processor is configured to receive capability information from the wireless terminal indicating that the wireless terminal has the ability to handle a PDU session release procedure involving sending and receiving the second NAS message.
The AMF node according to any one of Supplementary A1 to A9.
(Appendix A11)
The at least one processor is configured to receive the capability information from the wireless terminal in the procedure for registering the wireless terminal.
The AMF node described in Appendix A10.
(Appendix A12)
The at least one processor determines whether or not to utilize the PDU session release procedure with the transmission and reception of the second NAS message for the wireless terminal, depending on whether or not the capability information has been received. Configured to
AMF node according to Supplementary A10 or A11.
(Appendix A13)
It is a wireless terminal
At least one memory and
With at least one processor coupled to the at least one memory,
Equipped with
The at least one processor is configured to receive a first Non-Access Stratum (NAS) message containing a first Session Management (SM) container from the Access and Mobility Management Function (AMF).
The first SM container is a PDU Session transmitted from the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes Release Command message,
The first processor is to indicate that after receiving the first NAS message, the first PDU Session ID can be assigned to another PDU session different from the first PDU session. 2 NAS messages configured to be received from the AMF,
Wireless terminal.
(Appendix A14)
The second NAS message notifies the wireless terminal that the SM context for the first PDU session has been successfully released in the core network.
The wireless terminal according to the appendix A13.
(Appendix A15)
The at least one processor is a third NAS that includes a second SM container after the reception of the first NAS message and before the reception of the second NAS message.It is configured to send a message to the AMF
The second SM container includes a PDU Session Release Complete message transmitted from the wireless terminal to the SMF in order to respond to the PDU Session Release Command message.
The wireless terminal according to the appendix A13 or A14.
(Appendix A16)
It is understood that the at least one processor can assign the first PDU Session ID to a new PDU session different from the first PDU session in response to receiving the second NAS message. Is configured as
The wireless terminal according to any one of Supplementary A13 to A15.
(Appendix A17)
The second NAS message allows the wireless terminal to assign the first PDU Session ID to a new PDU session different from the first PDU session.
The wireless terminal according to any one of Supplementary A13 to A16.
(Appendix A18)
The at least one processor is configured not to assign the first PDU Session ID to a newly established PDU session until at least the second NAS message is received.
The wireless terminal according to any one of Supplementary A13 to A17.
(Appendix A19)
The at least one processor is configured to transmit capability information to the AMF indicating that the wireless terminal has the capability to handle a PDU session release procedure involving sending and receiving the second NAS message.
The wireless terminal according to any one of Supplementary A13 to A18.
(Appendix A20)
The at least one processor is configured to transmit the capability information to the AMF in the registration procedure of the wireless terminal.
The wireless terminal according to Appendix A19.
(Appendix A21)
A method for Access and Mobility Management Function (AMF) nodes,
A first Non-Access Stratum containing the first SM container in response to receiving a first control message containing the first Session Management (SM) container from the Session Management Function (SMF). NAS) Sending a message to a wireless terminal, wherein the first SM container indicates the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes PDU Session Release Command messages sent from to the wireless terminal; and
After sending the first NAS message to the wireless terminal, the second NAS to show that the first PDU Session ID can be assigned to another PDU session different from the first PDU session. Sending a message to the wireless terminal,
How to prepare.
(Appendix A22)
It is a method for wireless terminals,
Receiving a first Non-Access Stratum (NAS) message comprising a first Session Management (SM) container from the Access and Mobility Management Function (AMF), wherein the first SM container is the first. Includes a PDU Session Release Command message sent by the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the Protocol Data Unit (PDU) Session ID of.
After receiving the first NAS message, the AMF issues a second NAS message to indicate that the first PDU Session ID can be assigned to another PDU session different from the first PDU session. To receive from
How to prepare.
(Appendix A23)
A program that lets a computer do the method for an Access and Mobility Management Function (AMF) node.
The above method is
A first Non-Access Stratum containing the first SM container in response to receiving a first control message containing the first Session Management (SM) container from the Session Management Function (SMF). NAS) Sending a message to a wireless terminal, wherein the first SM container indicates the release of the first PDU session associated with the first Protocol Data Unit (PDU) Session ID. Includes PDU Session Release Command messages sent from to the wireless terminal; and
After sending the first NAS message to the wireless terminal, the second NAS to show that the first PDU Session ID can be assigned to another PDU session different from the first PDU session. Sending a message to the wireless terminal,
The program.
(Appendix A24)
It is a program to make a computer do the method for wireless terminals.
The above method is
Receiving a first Non-Access Stratum (NAS) message comprising a first Session Management (SM) container from the Access and Mobility Management Function (AMF), wherein the first SM container is the first. Includes a PDU Session Release Command message sent by the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session associated with the Protocol Data Unit (PDU) Session ID of.
After receiving the first NAS message, the AMF issues a second NAS message to indicate that the first PDU Session ID can be assigned to another PDU session different from the first PDU session. To receive from
The program.
[0155]
(Appendix B1)
Access and Mobility Management Function (AMF) node,
At least one memory and
With at least one processor coupled to the at least one memory,
Equipped with
The at least one processor is
The new PDU Session ID associated with the new Protocol Data Unit (PDU) session requested by the wireless terminal has not been successfully released. The first PDU Session ID associated with the existing first PDU session. Is configured to determine if it is the same as
If the new PDU Session ID is the same as the first PDU Session ID, it is configured to perform steps to avoid conflict between establishing the new PDU session and releasing the first PDU session. Be done,
AMF node.
(Appendix B2)
The at least one processor is configured to suspend the establishment of the new PDU session in the procedure until the release of the first PDU session is completed.
The AMF node described in Appendix B1.
(Appendix B3)
The at least one processor sends a Non-Access Stratum (NAS) message for establishing the new PDU session to the Session Management Function (SMF) in order to suspend the establishment of the new PDU session. Configured to deter,
AMF node described in Appendix B2.
(Appendix B4)
The at least one processor establishes the new PDU session without sending a Non-Access Stratum (NAS) message for establishing the new PDU session to the Session Management Function (SMF) within the procedure. A NAS message indicating rejection is configured to be sent to the wireless terminal.
The AMF node described in Appendix B1.
(Appendix B5)
The NAS message is a PDU Session Establishment Reject message,
The at least one processor is configured to generate the PDU Session Establishment Reject message.
AMF node described in Appendix B4.
(Appendix B6)
The PDU Session Establishment Reject message indicates a cause indicating that the PDU session establishment is temporarily rejected, and a backoff timer value.
The AMF node described in Appendix B5.
(Appendix B7)
The at least one processor exhibits a PDU Session ID conflict when sending a Non-Access Stratum (NAS) message to the Session Management Function (SMF) to establish the new PDU session within the procedure. Configured to send an indication to the SMF,
The AMF node described in Appendix B1.
(Appendix B8)
The at least one processor is configured to send the NAS message to the SMF with an indication indicating a collision of the PDU Session ID.
AMF node described in Appendix B7.
(Appendix B9)
The at least one processor is configured to receive the PDU Session Establishment Reject message from the SMF and send the PDU Session Establishment Reject message to the wireless terminal.
The PDU Session Establishment Reject message indicates a cause indicating that the PDU session establishment is temporarily rejected, and a backoff timer value.
AMF node according to Appendix B7 or B8.
(Appendix B10)
The at least one processor sends the NAS message to the AMF node without sending the Non-Access Stratum (NAS) message for establishing the new PDU session to the Session Management Function (SMF) within the procedure. Configured to be destroyed in
The AMF node described in Appendix B1.
(Appendix B11)
A method for Access and Mobility Management Function (AMF) nodes,
The new PDU Session ID associated with the new Protocol Data Unit (PDU) session requested by the wireless terminal has not been successfully released. The first PDU Session ID associated with the existing first PDU session. To determine if it is the same as, and
If the new PDU Session ID is the same as the first PDU Session ID, perform the procedure for avoiding the conflict of establishing the new PDU session and releasing the first PDU session.
How to prepare.
(Appendix B12)
A program that lets a computer do the method for an Access and Mobility Management Function (AMF) node.
The above method is
Related to a new Protocol Data Unit (PDU) session requested by a wireless terminal Determining if the new PDU Session ID that has been dismissed is the same as the first PDU Session ID associated with an existing first PDU session that has not been successfully released, and
If the new PDU Session ID is the same as the first PDU Session ID, perform the procedure for avoiding the conflict of establishing the new PDU session and releasing the first PDU session.
The program.
(Appendix B13)
Session Management Function (SMF) node,
At least one memory and
With at least one processor coupled to the at least one memory,
Equipped with
The at least one processor is
It is configured to receive the first NAS message for establishing a new Protocol Data Unit (PDU) session from the wireless terminal via the Access and Mobility Management Function (AMF).
The new PDU Session ID associated with the new PDU session is the same as the first PDU Session ID associated with an existing first PDU session that has not been successfully released. A second NAS message indicating a refusal to establish a PDU session is configured to be transmitted via the AMF to the radio terminal.
SMF node.
(Appendix B14)
In response to receiving an indication indicating a PDU Session ID collision from the AMF together with the first NAS message, the at least one processor sends the second NAS message to the wireless terminal via the AMF. Configured to send,
The SMF node described in Appendix B13.
(Appendix B15)
The second NAS message indicates a cause indicating that the establishment of the PDU session is temporarily rejected, and a backoff timer value.
The SMF node according to Appendix B13 or B14.
(Appendix B16)
A method for Session Management Function (SMF) nodes,
Receiving the first NAS message for establishing a new Protocol Data Unit (PDU) session from the wireless terminal via the Access and Mobility Management Function (AMF), and
The new PDU Session ID associated with the new PDU session is the same as the first PDU Session ID associated with an existing first PDU session that has not been successfully released. Sending a second NAS message indicating refusal to establish a PDU session to the wireless terminal via the AMF,
How to prepare.
(Appendix B17)
A program that lets a computer do the method for a Session Management Function (SMF) node.
The above method is
Receiving the first NAS message for establishing a new Protocol Data Unit (PDU) session from the wireless terminal via the Access and Mobility Management Function (AMF), and
The new PDU Session ID associated with the new PDU session is the same as the first PDU Session ID associated with an existing first PDU session that has not been successfully released. Sending a second NAS message indicating refusal to establish a PDU session to the wireless terminal via the AMF,
The program.

The scope of the claims
[Claim 1]
It is a wireless terminal
At least one memory and
With at least one processor coupled to the at least one memory,
Equipped with
The at least one processor is configured to assign a PDU Session ID that is different from the immediately used Protocol Data Unit (PDU) Session ID to the newly established PDU session.
Wireless terminal.
[Claim 2]
The value of the different PDU Session ID is generated by adding an increment to the value of the PDU Session ID used immediately before.
The wireless terminal according to claim 1.
[Claim 3]
The wireless terminal according to claim 1 or 2, wherein the at least one processor is configured to allocate one of a plurality of candidates for the value of the PDU Session ID to a newly established PDU session.
[Claim 4]
The wireless terminal according to any one of claims 1 to 3, wherein the at least one processor is configured to assign a different PDU Session ID to the new PDU session each time a new PDU session is established.
[Claim 5]
One of claims 1 to 4, wherein the at least one processor is configured to assign a PDU Session ID different from the immediately used at least one PDU Session ID to a newly established PDU session. The wireless terminal described in.
[Claim 6]
The at least one processor has a new PDU Session ID that is different from the first PDU Session ID assigned to the first PDU session during the first period associated with the release of the first PDU session. Configured to be assigned to a PDU session established in
The wireless terminal according to any one of claims 1 to 5.
[Claim 7]
The first processor responds to receiving a PDU Session Release Command message sent from the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session. It is configured not to assign the first PDU Session ID to a newly established PDU session during the period.
The wireless terminal according to claim 6.
[Claim 8]
The first during the first period in response to releasing the first PDU session based on receipt of a PDU Session Release Command message from the Session Management Function (SMF). PDU Session ID is configured not to be assigned to a newly established PDU session,
The wireless terminal according to claim 6.
[Claim 9]
The first during the first period, said at least one processor, in response to sending a PDU Session Release Complete message to approve the PDU Session Release Command message from the Session Management Function (SMF). Configured not to assign a PDU Session ID to a newly established PDU session,
The wireless terminal according to claim 6.
[Claim 10]
The at least one processor is configured to start a timer upon release of the first PDU session and not assign the first PDU Session ID to a newly established PDU session until the expiration of the timer. ,
The wireless terminal according to claim 6.
[Claim 11]
The at least one processor is configured to be set to the value of the first period.
The wireless terminal according to claim 6.
[Claim 12]
The at least one processor is the first PDU Session ID assigned to the first PDU session in at least the first attempt to establish a new PDU session after the release of the first PDU session. Configured to assign a different PDU Session ID to the new PDU session,
The wireless terminal according to any one of claims 1 to 5.
[Claim 13]
It is a method for wireless terminals,
Assigning a PDU Session ID different from the Protocol Data Unit (PDU) Session ID used immediately before to the newly established PDU session, and
Starting the PDU session establishment procedure using the different PDU Session ID,
How to prepare.
[Claim 14]
The value of the different PDU Session ID is generated by adding an increment to the value of the PDU Session ID used immediately before.
13. The method of claim 13.
[Claim 15]
The method according to claim 13 or 14, wherein the allocation comprises assigning one of a plurality of candidates for the value of the PDU Session ID to a newly established PDU session.
[Claim 16]
The method according to any one of claims 13 to 15, wherein the allocation comprises assigning a different PDU Session ID to the new PDU session each time a new PDU session is established.
[Claim 17]
The method of any one of claims 13-16, wherein the allocation comprises assigning a different PDU Session ID to a newly established PDU session in which at least one PDU Session ID used immediately before is assigned. ..
[Claim 18]
The assignment newly establishes a PDU Session ID different from the first PDU Session ID assigned to the first PDU session during the first period associated with the release of the first PDU session. Prepared to be assigned to a PDU session to be
The initiation comprises initiating a PDU session establishment procedure with the different PDU Session ID.
The method according to any one of claims 13 to 17.
[Claim 19]
The allocation is for the first period in response to receiving a PDU Session Release Command message sent from the Session Management Function (SMF) to the radio terminal to indicate the release of the first PDU session. In the meantime, the first PDU Session ID is not assigned to the newly established PDU session.
18. The method of claim 18.
[Claim 20]
The allocation is the first PDU during the first period in response to releasing the first PDU session based on the receipt of a PDU Session Release Command message from the Session Management Function (SMF). Be prepared to not assign a Session ID to a newly established PDU session
18. The method of claim 18.
[Claim 21]
The allocation is the first PDU Session during the first period in response to sending a PDU Session Release Complete message to approve the PDU Session Release Command message from the Session Management Function (SMF). Be prepared not to assign an ID to a newly established PDU session,
18. The method of claim 18.
[Claim 22]
The allocation comprises starting the timer in response to the release of the first PDU session and not assigning the first PDU Session ID to the newly established PDU session until the expiration of the timer.
18. The method of claim 18.
[Claim 23]
The assignment is a PDU different from the first PDU Session ID assigned to the first PDU session in at least the first attempt to establish a new PDU session after the release of the first PDU session. Provided to assign the Session ID to the new PDU session
The initiation comprises initiating a PDU session establishment procedure with the different PDU Session ID.
The method according to any one of claims 13 to 17.