Mobile communication systems
The system enables seamless slice control transitions by determining and switching to an alternative slice during handovers, addressing the lack of resource-based interruptions in 3GPP systems.
Patent Information
- Application Number
- JP2025500507
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-02-15
- Publication Date
- 2025-11-10
- Estimated Expiration
- 2043-02-15
AI Technical Summary
The 3GPP specifications do not provide a method for the Target RAN Node to determine when the core network is unable to continue providing the initial slice, leading to interruptions in slice control during handovers due to resource shortages.
A mobile communication system with a first and second base station, access management units, session management units, and a slice control management unit that communicate to determine whether the first slice can be continued or switched to a second slice during handovers, allowing seamless transition without interruption.
Ensures continuous slice control by switching to an alternative slice when resources are insufficient, maintaining service continuity during handovers.
Smart Images
Figure 0007766841000001 
Figure 0007766841000002 
Figure 0007766841000003
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to mobile communication systems. [Background technology]
[0002] The fifth generation mobile communication system (5GS) is characterized by providing communication services that are suited to the communication characteristics required by each use case by performing slice control according to the use case.
[0003] Typically, when a UE (User Equipment) initially connects to a network, it requests the network for the desired type of slice control (Requested NSSAI (Network Slice Selection Assistance Information)), and the network replies with the type of slice control it can provide (Allowed NSSAI) in response to the request, thereby determining the type of slice control, and slice control is performed.
[0004] Furthermore, when a UE moves between RAs (Registration Areas) and performs a handover, if the first slice control that the UE initially enjoyed becomes difficult to provide in the destination RA due to reasons such as a lack of resources on the core network side, the network can provide an alternative second slice control that can be provided, thereby enabling slice control to continue to be provided without interruption (see, for example, non-patent document 1).
[0005] Furthermore, according to the 3GPP (Third Generation Partnership Project) regulations, if it is difficult for the core network to continue providing the first slice when the UE performs handover, the Target RAN (Radio Access Network) Node sends a path switch request to the AMF requesting that slice control be switched from the first slice to the second slice. [Prior art documents] [Non-patent literature]
[0006] [Non-Patent Document 1] 3GPP TR 38.832 V17.0.0, 2021 Summary of the Invention [Problem to be solved by the invention]
[0007] However, 3GPP does not specify a method for a Target RAN Node to know that it is difficult for the core network side to continue providing the first slice.
[0008] For this reason, currently, the Target RAN Node cannot send a path switch request to the AMF (Access Management Function) triggered by the difficulty in continuing to provide the first slice on the core network side, and the PDU session cannot be switched to a new PDU session in the second slice, making it impossible to continue slice control.
[0009] Therefore, one or more aspects of the present disclosure aim to enable alternative slice control to continue even when it becomes difficult to provide the slice control currently being provided due to reasons such as a lack of resources on the core network side. [Means for solving the problem]
[0010] A mobile communication system according to a first aspect of the present disclosure comprises a first base station, a second base station, an access management unit that manages the registration of a mobile terminal that establishes a session with the first base station and the second base station in a slice, a session management unit that manages the session in the slice of the mobile terminal, and a slice control management unit that manages whether or not the slice can be controlled, wherein when the mobile terminal that has established a session in the first slice needs to perform a handover to the second base station, the first base station notifies the access management unit of the occurrence of a handover of the mobile terminal, the access management unit notifies the session management unit of the occurrence of a handover of the mobile terminal, and inquires the slice control management unit about whether or not the first slice can be continued in the second base station and whether or not registration can be made in a second slice different from the first slice in the second base station, and the session management unit inquires the slice control management unit about whether or not the session of the first slice in the second base station can be continued and whether or not a session of the second slice in the second base station can be established.
[0011] A mobile communication system according to a second aspect of the present disclosure includes a first base station, a second base station, a first access management unit that manages registration of a mobile terminal that establishes a session with the first base station in a slice, a second access management unit that manages registration of the mobile terminal that establishes a session with the second base station in a slice, a session management unit that manages a session in the slice of the mobile terminal, and a slice control management unit that manages whether or not slice control is possible, and when the mobile terminal that has established a session in the first slice needs to perform handover to the second base station, the first base station notifies the first access management unit of the occurrence of handover of the mobile terminal. The first access management unit notifies the second access management unit of the occurrence of handover of the mobile terminal, the second access management unit notifies the session management unit of the occurrence of handover of the mobile terminal, and inquires the slice control management unit about whether the first slice in the second base station can be continued and whether registration to a second slice different from the first slice in the second base station is possible, and the session management unit inquires the slice control management unit about whether the session of the first slice in the second base station can be continued and whether a session of the second slice in the second base station can be established. [Effects of the Invention]
[0012] According to one or more aspects of the present disclosure, alternative slice control can be continued even if it becomes difficult to provide the slice control currently being provided due to reasons such as a lack of resources on the core network side. [Brief explanation of the drawings]
[0013] [Figure 1] 1 is a block diagram schematically illustrating a configuration of a mobile communication system according to a first embodiment. [Figure 2] FIG. 3 is a sequence diagram showing an operation of the mobile communication system according to the first embodiment. [Figure 3]FIG. 10 is a block diagram schematically showing the configuration of a mobile communication system according to a second embodiment. [Figure 4] FIG. 10 is a sequence diagram showing an operation of the mobile communication system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0014] Embodiment 1 FIG. 1 is a block diagram schematically showing the configuration of a mobile communication system 100 according to the first embodiment. In FIG. 1, only elements related to this embodiment are shown, and other elements are omitted.
[0015] The mobile communication system 100 includes a user equipment (UE) 110, a radio access network (RAN) 120, and a core network 130.
[0016] The UE 110 is a mobile terminal. The RAN 120 is a network of radio base stations. The RAN 120 includes at least a Source RAN Node 121 to which the UE 110 was connected before the handover, and a Target RAN Node 122 to which the UE 110 is handed over. Here, the Source RAN Node 121 is also referred to as a source base station or a first base station, and the Target RAN Node 122 is also referred to as a destination base station or a second base station.
[0017] Core network 130 is a 5G core network. The core network 130 includes, as part of its functions, an access management function (AMF) 131, a session management function (SMF) 132, and a network slice admission control function (NSACF) 133.
[0018] The AMF 131 is a network access management function. Here, the AMF 131 functions as an access management unit that cooperates with the NSACF regarding the registration of the slice type of the UE 110 that accesses the Source RAN Node 121 and the Target RAN Node 122.
[0019] The SMF 132 is a function for managing a PDU (Protocol Data Unit) session. Here, the SMF 132 functions as a session management unit that cooperates with the NSACF to determine the slice type when a session of the UE 110 is established.
[0020] The NSACF 133 is a function for managing slice control permission. Here, the NSACF 133 functions as a slice control management unit that manages whether or not slice control is permitted for each slice type.
[0021] In the first embodiment, when UE 110, which has established a session in a first slice, needs to perform handover to target RAN node 122, Source RAN node 121 notifies AMF 131 of the occurrence of handover of UE 110. AMF 131 notifies SMF 132 of the occurrence of handover of UE 110, and queries NSACF 133 as to whether the first slice can be continued in target RAN node 122 and whether registration in a second slice different from the first slice in target RAN node 122 is possible. SMF 132 queries NSACF 133 as to whether the first slice can be continued in target RAN node 122 and whether a session in the second slice in target RAN node 122 is possible.
[0022] NSACF133 manages the number of registered UEs and the number of sessions for each slice, and if the number of registered UEs in the first slice has reached a predetermined upper limit and the number of registered UEs in the second slice has not reached a predetermined upper limit, it responds to AMF131 that registration in the second slice is possible. In addition, if the number of sessions in the first slice has reached a predetermined upper limit and the number of sessions in the second slice has not reached a predetermined upper limit, NSACF133 responds to SMF132 that a session can be established in the second slice.
[0023] When the AMF 131 receives a response from the NSACF 133 indicating that registration in the second slice is possible, the AMF 131 causes the UE 110 to register in the second slice. When the SMF 132 receives a response from the NSACF 133 indicating that a session can be established in the second slice, the SMF 132 causes the UE 110 to establish a session in the second slice at the Target RAN Node 122.
[0024] FIG. 2 is a sequence diagram showing the operation of the mobile communication system 100 according to the first embodiment. It is assumed that a first slice and a second slice, which is an alternative slice, are configured in advance as a slice mapping list in the Source RAN Node 121, the Target RAN Node 122, the AMF 131, and the SMF 132. It is also assumed that the UE 110 is registered for access in the first slice upon initial connection to the network, a first PDU session, which is a PDU session in the first slice, is established, and PDU session switching is configured to be performed, for example, in SSC mode 3 (Session and Service Continuity mode 3).
[0025] When the Source RAN node 121 currently accessed by the UE 110 recognizes that a handover is necessary due to movement between RAs, the Source RAN node 121 transmits a handover request in a first PDU session to the target RAN node 122 of the movement destination (S10).
[0026] Here, the UE 110 executes handover from the Source RAN node 121 to the Target RAN node 122. Specifically, the Target RAN node 122 transmits a handover command to the Source RAN node 121 (S11). In response to this, the Source RAN node 121 transmits a handover command to the UE 110 (S12). Upon receiving the handover command, the UE 110 switches the transmission destination from the Source RAN node 121 to the Target RAN node 122, and notifies the Target RAN node 122 that the handover has been completed (S13). At this point, the first PDU session, which is the PDU session in the first slice, is maintained.
[0027] Furthermore, when the UE 110 recognizes that a handover is necessary due to movement between RAs at the Source RAN Node 121 that the UE 110 is accessing, in addition to the operation in step S10, the UE 110 notifies the AMF 131 that a handover will occur (S14). In response to this, the AMF 131 notifies the SMF 132 of this fact (S15). Note that the processing of steps S14 and S15 may be performed before the processing of step S10.
[0028] The AMF 131 and SMF 132 inquire of the NSACF 133 whether the first slice can be continued and whether the second slice can be provided (S16). Specifically, AMF131 inquires whether UE110 can be registered in the first slice and whether UE110 can be registered in the second slice at the target RAN node, which is the handover destination, and SMF132 inquires whether a first PDU session, which is a PDU session to the first slice, can be established at the target RAN node, which is the handover destination, and whether a second PDU session, which is a PDU session to the second slice, can be established.
[0029] In response to this, the NSACF 133 replies whether the first slice can be continued and whether the second slice can be provided (S17). Specifically, an upper limit on the number of UEs that can be registered in one slice and an upper limit on the number of PDU sessions that can be established for one slice are set in the NSACF 133. The NSACF 133 also constantly monitors the number of UEs registered in one slice and the number of PDU sessions established for one slice. In step S16, in response to the inquiry from the AMF 131 regarding registration in the first slice and registration in the second slice, and the inquiry from the SMF 132 regarding establishment of the first PDU session and establishment of the second PDU session, the NSACF 133 responds to the AMF 131 and the SMF 132 depending on whether the numbers being monitored exceed the upper limits.
[0030] Here, AMF 131 and SMF 132 determine, based on the response from NSACF 133, that continuation of the first slice in Target RAN Node 122 is not possible and that provision of the second slice is possible. In other words, AMF 131 receives a response from NSACF 133 that registration to the first slice is not possible but registration to the second slice is possible, and SMF 132 receives a response that establishment of a session for the first slice is not possible but establishment of a session for the second slice is possible. In such a case, AMF 131 requests UE 110 to set the first slice and the second slice as Allowed NSSAI by sending a UE configuration update (S18).
[0031] Upon receiving such a request, the UE 110 completes the configuration of the first slice and the second slice, and then notifies the AMF 131 of the completion of the configuration (S19).
[0032] In addition, AMF 131 sends an update request to SMF 132 to change the PDU session by replacing the first slice with the second slice (S20).
[0033] Upon receiving such an update request, the SMF 132 notifies the UE 110 of the change from the first slice to the second slice using a NAS (Non-Access Stratum) PDU session change command (S21). As a result, UE 110 establishes a second PDU session, which is a PDU session in the second slice (S22).
[0034] When the SSC mode 3 timer expires (S23), the SMF 132 disconnects the PDU session in the first slice (S24). As a result, the AMF 131 changes the setting of the UE 110 by updating the UE configuration so that the second slice is the only slice allowed (S25).
[0035] By the above operation, the PDU session is switched from the first session to the second session without interruption, and slice control for UE 110 can be continued without interruption.
[0036] In the above, PDU session switching is performed using SSC mode 3, but it may also be performed using other PDU session switching methods.
[0037] Embodiment 2 FIG. 3 is a block diagram schematically showing a configuration of a mobile communication system 200 according to the second embodiment. In FIG. 3, only elements related to this embodiment are shown, and other elements are omitted.
[0038] The mobile communication system 200 includes a UE 110, a RAN 220, and a core network 230. The UE 110 in the mobile communication system 200 according to the second embodiment is similar to the UE 110 in the mobile communication system 100 according to the first embodiment.
[0039] The RAN 220 is a network of radio base stations. The RAN 220 includes at least a source RAN node 221 to which the UE 110 was connected before the handover, and a target RAN node 222 to which the UE 110 is handed over. Here, the source RAN node 221 is also referred to as a source base station or a first base station, and the target RAN node 222 is also referred to as a destination base station or a second base station.
[0040] Core network 230 is a 5G core network. The core network 230 includes, as part of its functions, a Source AMF 231A, a Target AMF 231B, an SMF 132, and an NSACF 133. The SMF 132 and NSACF 133 of the core network 230 in the second embodiment are the same as the SMF 132 and NSACF 133 of the core network 130 in the first embodiment.
[0041] Both the Source AMF 231A and the Target AMF 231B are network access management functions. In the second embodiment, the Source RAN Node 221 is connected to the Source AMF 231A, and the Target RAN Node 122 is connected to the Target AMF 231B.
[0042] The Source AMF 231A functions as a first access management unit that notifies the Target AMF 231B, which is connected at the handover destination, of the handover of the UE 110 accessing the Source RAN node 221. In addition, the Target AMF 231B functions as a second access management unit that cooperates with the NSACF regarding the registration of the slice type of the UE 110 that accesses the Target RAN Node 122.
[0043] In the second embodiment, when UE 110, which has established a session in a first slice, needs to perform handover to Target RAN node 222, Source RAN node 221 notifies Source AMF 231A of the occurrence of handover of UE 110. Source AMF 231A notifies Target AMF 231B of the occurrence of handover of UE 110. Target AMF 231B notifies SMF 132 of the occurrence of handover of UE 110, and queries NSACF 133 as to whether the first slice in Target RAN node 222 can be continued and whether registration in a second slice different from the first slice in Target RAN node 222 can be performed. The SMF 132 queries the NSACF 133 as to whether the first slice can be continued in the target RAN node 222 and whether a session of the second slice can be established in the target RAN node 222.
[0044] NSACF133 manages the number of registered UEs per slice and the number of sessions per slice, and if the number of registered UEs in the first slice has reached a predetermined upper limit and the number of registered UEs in the second slice has not reached a predetermined upper limit, it responds to Target AMF231B that registration in the second slice is possible. In addition, if the number of sessions in the first slice has reached a predetermined upper limit and the number of sessions in the second slice has not reached a predetermined upper limit, NSACF133 responds to SMF132 that a session can be established in the second slice.
[0045] When the Target AMF 231B receives a response indicating that registration in the second slice is possible from the NSACF 133, the Target AMF 231B causes the UE 110 to register in the second slice. Also, when the SMF 132 receives a response indicating that a session can be established in the second slice from the NSACF 133, the SMF 132 causes the UE 110 to establish a session in the second slice with the Target RAN Node 122.
[0046] FIG. 4 is a sequence diagram showing the operation of mobile communication system 200 according to the second embodiment. It is assumed that a first slice and a second slice, which is an alternative slice, are set in advance as a slice mapping list in the Source RAN Node 221, the Target RAN Node 222, the Source AMF 231A, the Target AMF 231B, and the SMF 132. It is also assumed that the UE 110 is registered for access in the first slice upon initial connection to the network, a first PDU session is established in the first slice, and PDU session switching is configured to be performed, for example, in SSC mode 3 (Session and Service Continuity mode 3).
[0047] When the UE 110 recognizes that a handover is necessary due to inter-RA movement in the Source RAN node 221 that the UE 110 is currently accessing, the Source RAN node 221 transmits a handover request in a first PDU session to the target RAN node 222 of the movement destination (S30).
[0048] Here, the UE 110 executes a handover from the Source RAN node 221 to the Target RAN node 222. Specifically, the Target RAN node 222 transmits a handover command to the Source RAN node 221 (S31). In response to this, the Source RAN node 221 transmits a handover command to the UE 110 (S32). Upon receiving the handover command, the UE 110 switches the transmission destination from the Source RAN node 221 to the Target RAN node 222, and notifies the Target RAN node 222 that the handover has been completed (S33). At this point, the first PDU session, which is the PDU session in the first slice, is maintained.
[0049] Furthermore, when the UE 110 recognizes that a handover is necessary due to movement between RAs in the Source RAN node 221 that the UE 110 is accessing, in addition to the operation in step S30, the UE 110 notifies the Source AMF 231A that a handover will occur (S34).
[0050] Upon receiving such a message, the Source AMF 231A notifies the UE 110 that a handover will occur by transmitting a message to the Target AMF 231B requesting the establishment of information related to the UE 110 (S35).
[0051] In response to this, the Target AMF 231B formulates information related to the UE 110, and further, the Target AMF 231B and the SMF 132 inquire of the NSACF 133 whether the first slice can be continued and whether the second slice can be provided (S36). Specifically, Target AMF231B inquires whether UE110 can be registered in the first slice at the Target RAN Node, which is the handover destination, and whether UE110 can be registered in the second slice, and SMF132 inquires whether a first PDU session, which is a PDU session to the first slice at the Target RAN Node, which is the handover destination, can be established, and whether a second PDU session, which is a PDU session to the second slice, can be established.
[0052] In response to this, the NSACF 133 replies whether the first slice can be continued and whether the second slice can be provided (S37). Specifically, the NSACF 133 is configured with an upper limit on the number of UEs that can be registered in one slice and an upper limit on the number of PDU sessions that can be established for one slice. The NSACF 133 also constantly monitors the number of UEs registered in one slice and the number of PDU sessions established for one slice. In step S36, in response to an inquiry from the Target AMF 231B regarding registration in the first slice and registration in the second slice, and an inquiry from the SMF 132 regarding establishment of the first PDU session and establishment of the second PDU session, the NSACF 133 responds to the AMF 131 and the SMF 132 depending on whether the monitored numbers exceed the upper limits.
[0053] Here, Target AMF 231B and SMF 132 determine that the first slice cannot be continued but that the second slice can be provided based on the response from NSACF 133. In other words, Target AMF 231B receives a response from NSACF 133 that registration to the first slice is not possible but registration to the second slice is possible, and SMF 132 receives a response that a session for the first slice cannot be established but a session for the second slice is possible.
[0054] Then, the Target AMF 231B requests the UE 110 to set the first slice and the second slice as Allowed NSSAIs by transmitting a UE Configuration Update to the UE 110 (S38).
[0055] Upon receiving such a request, the UE 110 completes the setting of the first slice and the second slice, and then notifies the Target AMF 231B of the completion of the setting (S39).
[0056] In addition, the Target AMF 231B transmits an update request to the SMF 132 to change the PDU session by replacing the first slice with the second slice (S40).
[0057] Upon receiving such an update request, the SMF 132 notifies the UE 110 of the change from the first slice to the second slice using a NAS PDU session change command (S41). As a result, UE 110 establishes a second PDU session, which is a PDU session in the second slice (S42).
[0058] When the SSC mode 3 timer expires (S43), the SMF 132 disconnects the PDU session in the first slice (S44). As a result, the Target AMF 231B changes the setting of the UE 110 by updating the UE configuration so that the second slice is the only slice allowed (S45).
[0059] By the above operation, the PDU session is switched from the first session to the second session without interruption, and slice control for UE 110 can be continued without interruption.
[0060] In the above, PDU session switching is performed using SSC mode 3, but it may also be performed using other PDU session switching methods.
[0061] The above-described AMF131, SMF132, NSACF133, Source AMF231A, and Target AMF231B can be realized by a computer. In addition, when each of AMF131, SMF132, NSACF133, Source AMF231A, and Target AMF231B is configured as a single computer, AMF131 is also called an access management device, SMF132 is also called a session management device, NSACF133 is also called a slice control device, Source AMF231A is also called a first access management device, and Target AMF231B is also called a second access management device. [Explanation of symbols]
[0062] 100,200 Mobile communication system, 110 UE, 120,220 RAN, 121,221 Source RAN Node, 122,222 Target RAN Node, 130,230 Core network, 131 AMF, 231A Source AMF, 231B Target AMF, 132 SMF, 133 NSACF.
Claims
1. a first base station; a second base station; and an access management unit that manages registration of a mobile terminal that establishes a session with the first base station and the second base station to a slice; a session management unit that manages sessions in the slice of the mobile terminal; A mobile communication system comprising: a slice control management unit that manages whether or not slices can be controlled; When the mobile terminal establishing a session in the first slice needs to perform handover to the second base station, the first base station notifies the access management unit of the occurrence of handover of the mobile terminal; The access management unit notifies the session management unit of the occurrence of handover of the mobile terminal, and inquires of the slice control management unit whether the first slice in the second base station can be continued and whether registration in a second slice different from the first slice in the second base station can be performed; The session management unit inquires of the slice control management unit about whether the session of the first slice in the second base station can be continued and whether the session of the second slice in the second base station can be established. A mobile communication system comprising:
2. The slice control management unit manages the number of registrations of the mobile terminal for each slice and the number of sessions for each slice, and when the number of registrations of the mobile terminal for the first slice reaches a predetermined upper limit and the number of registrations of the mobile terminal for the second slice does not reach the predetermined upper limit, responds to the access management unit that registration to the second slice is possible, and when the number of sessions of the first slice reaches a predetermined upper limit and the number of sessions of the second slice does not reach the predetermined upper limit, responds to the session management unit that a session can be established to the second slice.
2. The mobile communication system according to claim 1,
3. the access management unit causes the mobile terminal to register in the second slice when receiving a response indicating that the mobile terminal can be registered in the second slice from the slice control management unit; When the session management unit receives a response indicating that a session can be established in the second slice from the slice control management unit, the session management unit causes the mobile terminal to establish a session in the second slice in the second base station.
3. The mobile communication system according to claim 2, wherein:
4. a first base station; a second base station; and a first access management unit that manages registration of a mobile terminal that establishes a session with the first base station to a slice; a second access management unit that manages registration of the mobile terminal that establishes a session with the second base station to a slice; a session management unit that manages sessions in the slice of the mobile terminal; A mobile communication system comprising: a slice control management unit that manages whether or not slices can be controlled; When the mobile terminal having established a session in a first slice needs to perform handover to the second base station, the first base station notifies the first access management unit of the occurrence of handover of the mobile terminal; the first access management unit notifies the second access management unit of the occurrence of handover of the mobile terminal; the second access management unit notifies the session management unit of the occurrence of handover of the mobile terminal, and inquires of the slice control management unit whether the first slice in the second base station can be continued and whether registration in a second slice different from the first slice in the second base station can be performed; The session management unit inquires of the slice control management unit about whether the session of the first slice in the second base station can be continued and whether the session of the second slice in the second base station can be established. A mobile communication system comprising:
5. The slice control management unit manages the number of registrations of the mobile terminal for each slice and the number of sessions for each slice, and when the number of registrations of the mobile terminal for the first slice reaches a predetermined upper limit and the number of registrations of the mobile terminal for the second slice does not reach the predetermined upper limit, responds to the second access management unit that registration to the second slice is possible, and when the number of sessions of the first slice reaches a predetermined upper limit and the number of sessions of the second slice does not reach the predetermined upper limit, responds to the session management unit that a session can be established to the second slice.
5. The mobile communication system according to claim 4, wherein:
6. the second access management unit causes the mobile terminal to register in the second slice when receiving a response indicating that the mobile terminal can be registered in the second slice from the slice control management unit; When the session management unit receives a response indicating that a session can be established in the second slice from the slice control management unit, the session management unit causes the mobile terminal to establish a session in the second slice in the second base station.
6. The mobile communication system according to claim 5,