Base station and QoS flow control method

Abstract

To provide a base station and a QoS flow control method which can suppress reduction in performance of a mobile communication system.SOLUTION: A base station 200 performs radio communication with a user device 100. The base station 200 includes a first radio unit 211 and a second radio unit 221 which can perform radio communication with the user device 100. The base station 200 comprises: a first dispersion unit 212 which is connected to the first radio unit 211 and includes a first scheduler 213 for a first service; and a second dispersion unit 222 which is connected to the second radio unit 221 and includes a second scheduler 223 for a second service different from the first service. Further, the base station 200 includes a control part 252 which controls the first dispersion unit 212 and the second dispersion unit 222. The control part 252 selects any of the first dispersion unit 212 and the second dispersion unit 222 for an established QoS flow to perform communication with the user device 100.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a base station and a QoS flow control method. [Background technology]

[0002] In some regions, the operation of the 5th generation mobile communication (5G) system (hereinafter, sometimes referred to as "5G system") has started. The 3rd Generation Partnership Project (3GPP) specifies three types of performance requirements for the 5G system: eMBB (enhanced Mobile Broadband), URLLC (Ultra-Reliable and Low Latency Communications), and mMTC (massive Machine Type Communications). By imposing such performance requirements on the 5G system, it becomes possible to build a 5G system that supports, for example, various use cases (or services).

[0003] In the 5G system, there is a base station called gNB (next generation Node B). A gNB is allowed to have a configuration in which multiple gNB-DUs (Distributed Units) are connected to one gNB-CU (Central Unit). This configuration enables flexible system design by, for example, separating functions between the gNB-CU and gNB-DU.

[0004] In addition, in the 5G system, it is possible to provide a quality of service (QoS) service for each IP flow to a user device (UE: User Equipment). In the 5G system, a QoS flow is established when a protocol data unit (PDU) session is established (PDU Session Establishment) or updated (PDU Session Modification). The QoS flow is established between a user device (UE: User Equipment) and a user plane function (UPF) under the control of a session management function (SMF). The user device can receive the QoS service for each QoS flow. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TS 23.501 V16.10.0 (2021-09) [Non-Patent Document 2] 3GPP TS 23.502 V16.10.0 (2021-09) [Non-Patent Document 3] 3GPP TS 38.300 V16.7.0 (2021-09) [Non-Patent Document 4] 3GPP TS 38.401 V16.7.0 (2021-10) Summary of the Invention [Problem to be solved by the invention]

[0006] One aspect of the present invention is to provide a base station and a QoS flow control method that are adapted to suppress degradation in performance of a mobile communication system. [Means for solving the problem]

[0007] A base station according to a first aspect is a base station that performs wireless communication with a user device. The base station has a first wireless unit and a second wireless unit that can perform wireless communication with the user device. The base station also has a first distributed unit connected to the first wireless unit and including a first scheduler for a first service, and a second distributed unit connected to the second wireless unit and including a second scheduler for a second service different from the first service. The base station further has a control unit that controls the first distributed unit and the second distributed unit. The control unit selects either the first distributed unit or the second distributed unit for an established QoS flow and communicates with the user device.

[0008] A QoS flow control method according to a second aspect is a QoS flow control method in a base station that performs wireless communication with a user device. The base station has a first wireless unit and a second wireless unit that can perform wireless communication with the user device. The base station also has a first distributed unit connected to the first wireless unit and including a first scheduler for a first service, and a second distributed unit connected to the second wireless unit and including a second scheduler for a second service different from the first service. The base station further has a control unit that controls the first distributed unit and the second distributed unit. The QoS flow control method includes a step of selecting, by the control unit, either the first distributed unit or the second distributed unit for an established QoS flow, and communicating with the user device. Effect of the Invention

[0009] According to one aspect, it is possible to provide a base station and a QoS flow control method that are adapted to suppress degradation in performance of a mobile communication system. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system according to an embodiment. [Diagram 2] FIG. 2A is a diagram showing an example of the configuration of a CU according to an embodiment, and FIG. 2B is a diagram showing an example of the configuration of a DU according to an embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of the configuration of an RU according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of an operation according to an embodiment. [Diagram 5] FIG. 5 is a flowchart illustrating an example of a DU selection process according to an embodiment. [Figure 6] FIG. 6 is a flowchart illustrating an example of a DU selection process according to an embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of an intra-CU handover operation according to an embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of an operation according to an embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of an intra-CU handover operation according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] As described above, in the 5G system, QoS services can be provided by QoS flows. In addition, a gNB can set multiple QoS flows in one gNB-DU.

[0012] However, having different types of QoS flows configured in one gNB-DU may degrade the performance of the entire 5G system.

[0013] For example, there are three types of QoS flows: GBR (Guaranteed Bit Rate), Non-GBR, and Delay Critical GBR. Among these, Delay Critical GBR has the strictest operating conditions compared to other types. When a QoS flow of Delay Critical GBR and another QoS flow are set in one gNB-DU, if the QoS flow of Delay Critical GBR is prioritized, the operation can be guaranteed for the QoS flow, but the other QoS flows are affected, and the throughput may decrease in the gNB-DU. In addition, for Delay Critical GBR, the scheduling process is likely to be complicated, and a situation may occur in which the throughput of the entire 5G system is likely to decrease.

[0014] Also, for example, even if a QoS flow for URLLC and a QoS flow other than URLLC are configured in one gNB-DU, if the QoS flow for URLLC is prioritized, this may have an impact, such as a decrease in the throughput of the QoS flows other than URLLC in that gNB-DU.

[0015] The impact of such QoS flows may affect not only the gNB-DU in question, but the entire gNB, and even the entire 5G system.

[0016] Therefore, an object of this embodiment is to suppress such performance degradation in a 5G system (or a mobile communication system).

[0017] In order to solve such a problem, in this embodiment, a scheduler for a different service is set for each gNB-DU. Then, in this embodiment, when a QoS flow is established, the gNB-CU selects one of the gNB-DUs for the QoS flow.

[0018] As a result, for example, an established QoS flow is processed in one of the distributed units (gNB-DU), and the scheduler of the distributed unit can schedule the QoS flow. Therefore, even if multiple QoS flows are established, each QoS flow can be processed in a different distributed unit, and the influence of each QoS flow on each other can be suppressed. Therefore, it is possible to suppress the degradation of performance not only of the base station but also of the entire mobile communication system.

[0019] Hereinafter, the embodiments will be described in detail with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. [Example of a mobile communication system configuration] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system 10 according to an embodiment.

[0020] As shown in FIG. 1, the mobile communication system 10 includes a UE 100, a gNB 200, and a CN (Core Network) 300.

[0021] The UE 100 is, for example, a smartphone, a feature phone, an IoT (Internet of Things) device, a personal computer, etc. In the example of Fig. 1, an example of one UE 100 is shown, but there may be a plurality of UEs.

[0022] The gNB 200 is an example of a base station. The gNB 200 functions as a base station in a 5G system. The gNB 200 performs wireless communication with the UE (or user equipment) 100 and provides various services to the UE 100. Instead of the gNB, an en-gNB or the like may be used.

[0023] In addition, the network between UE100 and gNB200 may be called NG-RAN (Next Generation-Radio Access Network) or RAN in a 5G system.

[0024] The CN300 is a network between the gNB200 and functional units (or functional entities) in the CN300. The functional units in the CN300 include an SMF, an AMF (Access and Mobility Management Function), and a UPF. The functional units in the CN300 establish or update a PDU session. The functional units can also transmit user data to the UE100 via the gNB200, and transmit user data transmitted from the UE100 to another network.

[0025] (Example of gNB configuration) As shown in FIG. 1, gNB200 has a CU250, multiple DUs 212, 222, 232, and multiple RUs (Radio Units) 211, 221, 231.

[0026] The CU 250 may be referred to as an aggregation unit, for example. The CU 250 is connected to each of the DUs 212, 222, and 232, and controls each of the DUs 212, 222, and 232. The CU 250 can select one of the multiple DUs 212, 222, and 232 to communicate with the UE 100. The CU 250 is connected to the CN 300, and transmits and receives user data and the like to and from the CN 300.

[0027] Each of the DUs 212, 222, and 232 may be referred to as a distributed unit, for example. The DU #1 (212) is connected to the CU 250 and is also connected to the RU #1 (211). The DU #2 (222) is connected to the CU 250 and is also connected to the RU #2 (221). The DU #3 (232) is connected to the CU 250 and is also connected to the RU #3 (231).

[0028] The DUs 212, 222, and 232 respectively include schedulers 213, 223, and 233. When performing wireless communication with the UE 100, the scheduler #1 (213) performs a scheduling process such as allocating wireless resources to the UE 100. The other schedulers 223 and 233 operate in a similar manner.

[0029] Each of the RUs 211, 221, and 231 may be referred to as a radio unit, for example. RU#1 (211) (e.g., a first radio unit) is controlled by DU#1 (212) and is capable of wireless communication with the UE 100. Also, RU#2 (221) (e.g., a second radio unit) is controlled by DU#2 (222) and is capable of wireless communication with the UE 100. Furthermore, RU#3 (231) is controlled by DU#3 (232) and is capable of wireless communication with the UE 100.

[0030] As shown in Figure 1, RAN #1 (210) includes DU #1 (212) and RU #1 (211). RAN #2 (220) includes DU #2 (222) and RU #2 (221). RAN #3 (230) includes DU #3 (232) and RU #3 (231).

[0031] In one embodiment, each of the schedulers 213, 223, and 233 is a scheduler for a different service.

[0032] First, the service may be any one of eMBB, URLLC, and mMTC. For example, scheduler #1 (213) is a scheduler for eMBB, scheduler #2 (223) is a scheduler for URLLC, and scheduler #3 (233) is a scheduler for mMTC. For example, scheduler #1 (213) may be a first scheduler for a first service, and scheduler #2 (223) may be a second scheduler for a second service.

[0033] In the scheduler for eMBB, for example, scheduling may be performed to allocate a large amount of radio resources to UE 100 in a good radio condition. In addition, in the scheduler for URLLC, a radio resource region that can be interrupted for URLLC may be reserved in advance, and scheduling may be performed to allocate the radio resources to UE 100. Furthermore, in the scheduler for mMTC, in consideration of the possibility that wireless communication may be performed simultaneously from a large number of UEs 100, a radio resource region may be reserved in advance, and scheduling may be performed to allocate the radio resources to UE 100.

[0034] Secondly, the service may be any one of GBR, Non-GBR, and Delay Critical GBR. For example, scheduler #1 (213) is a scheduler for GBR, scheduler #2 (223) is a scheduler for Non-GBR, and scheduler #3 (233) is a scheduler for Delay Critical GBR. Each scheduler 213, 223, and 233 may reserve a radio resource area in advance so as to obtain QoS characteristics corresponding to the type of QoS flow (or resource type), and may perform scheduling to allocate the radio resource to UE 100.

[0035] However, for one service, multiple schedulers may be set as schedulers for that service. For example, scheduler #1 (213) and scheduler #2 (223) may be set as schedulers for URLLC. Also, for example, scheduler #1 (213) and scheduler #2 (223) may be set as schedulers for Delay Critical GBR. These services are more likely to affect other services than others, and multiple schedulers can provide more radio resources to UE 100.

[0036] For the established QoS flow, the CU 250 selects one of the multiple DUs 212, 222, and 232. This allows the CU 250 to cause any one of the schedulers 213, 223, and 233 that corresponds to (or matches) the QoS flow to perform the scheduling process for the QoS flow.

[0037] In the following, the DU #1 (212) may be described as a representative of the multiple DUs 212, 222, and 232. Also, the RU #1 (211) may be described as a representative of the multiple RUs 211, 221, and 231. Furthermore, the scheduler #1 (213) may be described as a representative of the multiple schedulers 213, 223, and 233.

[0038] (Examples of CU, DU, and RU configurations) FIG. 2A is a diagram illustrating an example of the configuration of a CU 250 according to an embodiment.

[0039] As shown in FIG. 2A, the CU 250 includes an interface unit 251 and a control unit 252.

[0040] The interface unit 251, under the control of the control unit 252, transmits and receives messages to and from the CN 300, and transmits and receives messages to and from any of the multiple DUs 212, 222, and 232. For example, the interface unit 251 transmits and receives messages of an NG interface to the CN 300, and transmits and receives messages of an F1 interface to and from each of the DUs 212, 222, and 232.

[0041] The control unit 252 performs various controls in the CU 250. The control unit 252 selects one of the multiple DUs 212, 222, 232 for the established QoS flow. Then, the control unit 252 causes the scheduler 213, 223, 233 of the selected DU 212, 222, 232 to perform scheduling processing for the QoS flow. Details will be described in an operation example.

[0042] 2B is a diagram showing an example of the configuration of the DU #1 (212) according to an embodiment. The other DU #2 (222) and DU #3 (232) have the same configuration as the DU #1 (212).

[0043] As shown in FIG. 2B, the DU #1 (212) has an interface unit 2120 and a control unit 2121.

[0044] The interface unit 2120 transmits and receives messages to and from the CU 250 and transmits and receives messages to and from the RU #1 (211) under the control of the control unit 2121. For example, the interface unit 2120 transmits and receives messages of the F1 interface to and from the CU 250, and transmits and receives messages of the O-RAN (Open Radio Access Network) fronthaul specification to and from the RU #1 (211).

[0045] The control unit 2121 performs various controls in the DU #1 (212). The control unit 2121 includes a scheduler #1 (213).

[0046] FIG. 3 is a diagram illustrating an example of the configuration of the RU #1 (211) according to an embodiment.

[0047] The interface unit 2110 transmits and receives messages to and from the DU #1 (212), and transmits and receives data to and from the wireless processing unit 2111. That is, the interface unit 2110 extracts data, control signals, etc. from messages received from the DU #1 (212), and outputs the extracted data, control signals, etc. to the wireless processing unit 2111. In addition, the interface unit 2110 generates a message in a predetermined format including the data, control signals, etc. output from the wireless processing unit 2111, and outputs the message to the DU #1 (212).

[0048] The wireless processing unit 2111 converts (up-converts) the data or control signal output from the interface unit 2110 into a wireless signal in a wireless band, and outputs the wireless signal to the antenna 2112. The wireless processing unit 2111 also converts (down-converts) the wireless signal output from the antenna 2112 into data or a wireless signal in a baseband, and outputs the data or wireless signal to the interface unit 2110.

[0049] The antenna 2112 transmits the radio signal output from the radio processing unit 2111 to the UE 100. The antenna 2112 also receives the radio signal transmitted from the UE 100, and outputs the received radio signal to the radio processing unit 2111. The antenna 2112 receives and transmits the radio signal by using the radio resources allocated by the scheduler #1 (213).

[0050] (QoS flow) Here, the QoS flow will be described.

[0051] A QoS flow is the finest granularity in distinguishing QoS in a PDU session. The QoS flow is controlled by the SMF of the CN 300. The QoS flow is established in a PDU Session Establishment procedure or a PDU Session Modification procedure. The QoS flow may be pre-configured.

[0052] In the 5G system, a QoS flow ID (QFI: QoS Flow ID) is used to identify a QoS flow, and a QoS ID (5QI: 5G QoS Identifier) ​​is used to identify each QoS.

[0053] Each QoS flow is associated with QoS parameters and QoS characteristics. The QoS parameters include 5QI, ARP (Allocation and Retention Priority) including information such as priority, etc. The QoS characteristics include resource type, priority level, packet error rate, maximum delay time allowed between UE 100 and UPF (Packet Delay Budget), etc. The QoS flow can be characterized by such QoS parameters and QoS characteristics.

[0054] The QoS profile is defined as including QoS parameters. The QoS profile is transmitted together with the QFI from the SMF via the AMF to the RAN. Specifically, the QoS profile and the QFI are transmitted to the RAN using the N2 interface during a PDU session establishment procedure or a PDU session update procedure. The QoS characteristics are also transmitted to the RAN as part of the QoS profile. A PDU session including one or more QoS flows is established between the UE 100 and the UPF by the PDU session establishment procedure or the PDU session update procedure.

[0055] In the gNB 200 (or RAN), each QoS flow is mapped to a RAN resource (i.e., a data bearer) based on the QoS profile and the QFI. In this case, as described above, the CU 250 of the gNB 200 selects one of the multiple DUs 212, 222, and 232, and causes the selected DU to perform processing for the established QoS flow.

[0056] (Example of operation) Next, an example of operation will be described.

[0057] The CU 250 may select the DUs 212, 222, and 232 when the UE 100 makes an initial connection with the gNB 200. In addition, the CU 250 may select the DUs 212, 222, and 232 when the UE 100 selects a service. In addition, the CU 250 may select the DUs 212, 222, and 232 when the UE 100 terminates a service.

[0058] In the operation examples, an operation example (operation example 1) in which the UE 100 selects a service and an operation example (operation example 2) in which the UE 100 ends the service will be described.

[0059] (Example 1) 4 to 7 are diagrams illustrating an operation example (operation example 1) according to an embodiment. Here, an example in which the UE 100 selects the URLLC service will be described.

[0060] It is assumed that UE 100 is connected to RAN #1 (or RU #1 (211)). Also, it is assumed that scheduler #1 (213) of DU #1 (212) is set as a scheduler for eMBB, scheduler #2 (223) of DU #2 (222) is set as a scheduler for URLLC, and scheduler #3 (233) of DU #3 (232) is set as a scheduler for mMTC.

[0061] As shown in FIG. 4, in step S10, the UE 100 selects a URLLC service and starts executing an application for URLLC.

[0062] Steps S11 to S14 represent an example of a procedure for establishing a PDU session through URLLC service selection.

[0063] That is, in step S11, the UE 100 transmits a PDU Session Establishment request to the CN 300 via the RAN#1 (210) and the CU 250. The PDU Session Establishment request includes information about the URLLC that the UE 100 has started to execute (or that the UE 100 has selected). The information may be S-NSSAI (Network Slice Selection Assistance Information).

[0064] In step S12, the CN 300 transmits an N2PDU session request to the CU 250. The N2PDU session request includes a PDU session ID. The N2PDU session request also includes a PDU session establishment accept that permits the establishment of the requested PDU session. The N2PDU session request further includes N2 SM information and the like. The N2 SM information includes information for establishing a QoS flow for URLLC. Specifically, the above-mentioned QoS profile and the corresponding QFI are included. By receiving the N2PDU session request, the CU 250 can recognize that a QoS flow for URLLC has been established based on the N2 SM information.

[0065] In step S13, the UE 100 and the CU 250 execute an AN-specific resource setup via the RAN #1 (210). Specifically, the CU 250 transmits a PDU session ID, a PDU session establishment accept, and the like to the UE 100 via the RAN #1 (210).

[0066] In step S14, the CU 250 transmits an N2 PDU session response to the CN 300. The N2 PDU session response includes a PDU session ID, N2 SM information, and the like.

[0067] As a result of the above, a PDU session including a QoS flow for URLLC is established between the UE 100 and the UPF.

[0068] In step S15, the CU 250 performs a DU selection process.

[0069] FIG. 5 is a flowchart illustrating an example of a DU selection process according to an embodiment.

[0070] As shown in FIG. 5, in step S150, the control unit 252 of the CU 250 starts the process.

[0071] In step S151, the control unit 252 receives N2 SM information.

[0072] In step S152, the control unit 252 selects one of the DUs 212, 222, and 232 for the QoS flow established by the N2 SM information. That is, the control unit 252 selects the DU#1 (212) (e.g., the first distributed unit) when the QoS flow is a QoS flow for a first service, and selects the DU# (222) (e.g., the second distributed unit) when the QoS flow is a QoS flow for a second service.

[0073] For example, when the established QoS flow is a QoS flow for URLLC by the process of Fig. 4, the control unit 252 selects the DU #2 (222) having the scheduler #2 (223) for URLLC. Also, when the established QoS flow is a QoS flow for eMBB, the control unit 252 selects, for example, the DU #1 (212) having the scheduler #1 (213) for eMBB. Furthermore, when the established QoS flow is a QoS flow for mMTC, the control unit 252 selects, for example, the DU #3 (232) having the scheduler #2 (233) for mMTC.

[0074] However, when a QoS flow for URLLC is established and the control unit 252 selects DU#2 (222), the UE 100 connects to RU#1 (211) on the RAN#1 (210) side, but the CU 250 selects DU#2 (222) on the RAN#2 (220) side.

[0075] In this way, when the RU#1 (211) to which the UE100 is connected and the DU#2 (222) selected by the CU250 belong to different RANs, the CU250 switches the connection destination of the UE100 to the RAN#2 (220) to which the selected DU#2 (222) belongs. Specifically, the CU250 executes an intra-CU handover to switch the connection destination of the UE100 from the RU#1 (211) to the RU#2 (221). FIG. 7 shows an example of the operation of the intra-CU handover. The explanation of FIG. 7 will be given later. Step S152 may also include a handover process when the RAN to which the UE100 is connected is different from the DU (or RAN) selected by the control unit 252.

[0076] In step S153, the control unit 252 ends the series of processes.

[0077] 6 is a flowchart illustrating an example of a DU selection process according to an embodiment of the present invention. The DU selection process in FIG. 6 may be another example of the DU selection process in FIG.

[0078] It is assumed that, for example, Delay Critical GBR is set in DU#2 (222) before the process in Fig. 6 is started. Also, it is assumed that UE 100 is connected to RAN#1 (RU#1 (211)) as in the case of Fig. 5.

[0079] In step S150, the control unit 252 starts the process.

[0080] In step S151, similarly to FIG. 5, the control unit 252 receives N2 SM information.

[0081] In step S154, the control unit 252 determines whether or not a Delay Critical GBR is set based on the N2 SM information. If a Delay Critical GBR is set (YES in step S154), the process proceeds to step S155. On the other hand, if a Delay Critical GBR is not set (NO in step S154), the process proceeds to step S157. For example, the control unit 252 may determine whether or not a Delay Critical GBR is set as a QoS flow for URLLC.

[0082] In step S155, the control unit 252 executes an intra-CU handover to the RAN#2 220. For example, the process shown in FIG.

[0083] Returning to FIG. 6, in step S156, the control unit 252 ends the series of processes.

[0084] On the other hand, in step S157, the control unit 252 distributes GBR based on the number of GBR connections. If the number of GBR connections is concentrated in one DU, the bandwidth will be occupied, so the control unit 252 distributes GBR in consideration of the GBR connection status in each DU 212, 222, 232. In the example of Fig. 6, in steps S158 and S159, the control unit 252 distributes each GBR to DU #1 (212) and DU #3 (232) other than DU #2 (222) for which Delay Critical GBR is set, so that the number of GBR connections is equal.

[0085] Then, in step S156, the control unit 252 ends the series of processes.

[0086] Fig. 7 is a diagram showing an example of an intra-CU handover operation according to an embodiment. Fig. 7 shows an example of processing after the DU selection shown in Fig. 4, in which the connection of the UE 100 is switched from RAN#1 (210) (or RU#1 (211)) to RAN#2 (220) (or RU#2 (221)) by intra-CU handover (for example, an example of a first switching process).

[0087] In step S16, the CU 250 transmits a UE context setup request (UE CONTEXT SETUP REQUEST) to the RAN#2 (220).

[0088] In step S17, the RAN#2 (220) sends a UE context setup response (UE CONTEXT SETUP RESPONSE) to the CU250.

[0089] In step S18, the CU 250 transmits a UE context modification request (UE CONTEXT MODIFICATION REQUEST) including an RRC reconfiguration to the RAN#1 (210).

[0090] In step S19, the RAN#1 (210) transmits an RRC re-establishment to the UE 100.

[0091] In step S20, the UE 100 executes a random access procedure for the RAN#2 (220) to which the UE 100 is to be connected.

[0092] In step S21, the UE 100 transmits an RRC reconfiguration complete message to the RAN#2 (220).

[0093] In step S22, the CU 250 sends a UE context release command (UE CONTEXT RELEASE COMMAND) to the RAN #1 (210).

[0094] In step S23, the RAN#1 (210) deletes the UE context of the UE 100, and then transmits a UE context release completion (UE CONTEXT RELEASE COMPLETE) to the CU 250.

[0095] (Example 2) Next, an operation example 2 will be described. The operation example 2 is an operation example in which the UE 100 ends a service. Specifically, the operation example is an operation example in which the UE 100 selects a URLLC service by the processes shown in Figs. 4 to 7 and then ends the selected URLLC service.

[0096] It is assumed that the UE 100 is connected to the RAN #2 (220) (RU #2 (221)) by intra-CU handover (FIG. 7). The setting status of each scheduler 213, 223, and 233 is the same as in the first operation example.

[0097] FIG. 8 is a diagram illustrating an operation example (operation example 2) according to an embodiment.

[0098] In step S30, the UE 100 ends the URLLC service by terminating the application for URLLC.

[0099] Steps S31 to S34 represent an example of a PDU session update procedure.

[0100] That is, in step S31, the UE 100 transmits a PDU session modification request to the CN 300 via the RAN#2 (220) and the CU 250. The PDU session modification request includes information about the URLLC that has been completed (or terminated) by the UE 100. The information may be the S-NSSAI.

[0101] In step S32, the CN 300 transmits an N2 session request to the CU 250. The N2 session request includes a PDU session ID, a PDU session modification command instructing an update of the PDU session, and N2 SM information. The N2 SM information includes information for updating the QoS flow for URLLC. Specifically, it includes the above-mentioned QoS profile and the corresponding QFI. By receiving the N2 session request, the CU 250 can know that the QoS flow for URLLC has been updated.

[0102] In step S33, the UE 100 and the CU 250 perform an AN-specific resource modification via the RAN #2 (220). Specifically, the CU 250 transmits a PDU Session Modification Accept to the UE 100 via the RAN #2 (220), and the UE 100 transmits a PDU Session Modification Ack to the CU 250 via the RAN #2 (220).

[0103] In step S34, the CU250 transmits an N2 Session Response to the CN300.

[0104] As a result of the above, the PDU session including the QoS flow for URLLC can be updated between the UE 100 and the UPF.

[0105] In step S35, the CU250 performs a DU selection process. The CU250 performs the DU selection process (FIG. 5 or FIG. 6) in the same manner as in the first operation example. In this case, the CU250 first selects the DU #1 (212) on the RAN #1 (210) side to which the UE100 is connected. The CU250 may select a DU (DU #1 (212) or DU #3 (232)) other than the DU #2 (222) having the scheduler #2 (223) for URLLC.

[0106] In this case, the RAN#1 (210) selected by the CU 250 is different from the RAN2 (220) to which the UE 100 is currently connected. Therefore, the CU 250 executes an intra-CU handover (e.g., a second switching process) for the UE 100 to switch the connection destination from the RU#2 (221) to the RU#1 (211).

[0107] FIG. 9 is a diagram illustrating an example of an intra-CU handover operation according to an embodiment.

[0108] In step S36, the CU 250 transmits a UE context setup request (UE CONTEXT SETUP REQUEST) to the RAN#1 (210).

[0109] In step S37, the RAN#1 (210) sends a UE context setup response (UE CONTEXT SETUP RESPONSE) to the CU250.

[0110] In step S38, the CU 250 transmits a UE context modification request (UE CONTEXT MODIFICATION REQUEST) including an RRC reconfiguration to the RAN#2 (220).

[0111] In step S39, the RAN#2 (220) transmits an RRC re-establishment to the UE 100.

[0112] In step S40, the UE 100 executes a random access procedure with the RAN#1 (210) to which the UE 100 is to be connected.

[0113] In step S41, the UE 100 transmits an RRC reconfiguration complete message to the RAN#1 (210).

[0114] In step S42, the CU 250 transmits a UE context release command (UE CONTEXT RELEASE COMMAND) to the RAN #2 (220).

[0115] In step S43, the RAN#2 (220) deletes the UE context of the UE 100, and then transmits a UE context release completion (UE CONTEXT RELEASE COMPLETE) to the CU 250.

[0116] (effect) As described above, a base station (e.g., gNB 200) that performs wireless communication with a user device (e.g., UE 100) has a first wireless unit (e.g., RU #1 (211)) and a second wireless unit (e.g., RU #2 (221)) that can perform wireless communication with the user device. The base station also has a first distributed unit (e.g., DU #1 (212)) that is connected to the first wireless unit and includes a first scheduler (e.g., scheduler #1 (213)) for a first service, and a second distributed unit (e.g., DU #2 (222)) that is connected to the second wireless unit and includes a second scheduler (e.g., scheduler #2 (223)) for a second service different from the first service. Furthermore, the base station has a control unit (e.g., control unit 252) that controls the first distributed unit and the second distributed unit. The control unit selects either the first distributed unit or the second distributed unit for the established QoS flow and communicates with the user device. According to such a configuration, the following effects can be obtained.

[0117] That is, as described above, in the embodiment, a certain QoS flow can be processed by the DU #2 (222), and another type of QoS flow can be processed by the DU #1 (212). That is, even if multiple QoS flows are established, each QoS flow can be processed by a different DU. Therefore, it is possible to suppress the influence of a certain QoS flow on other QoS flows, and it becomes easy to achieve the performance of each QoS flow (for example, reduction of the packet error rate, etc.). Therefore, in the gNB 200, it is possible to suppress the performance degradation, and further, it is possible to suppress the performance degradation of the entire mobile communication system 10 (or the 5G system).

[0118] Also, in each DU 212, 222, 232, a different scheduler 213, 223, 233 is set for each service. Therefore, it is possible to implement a RAN scheduler specialized for a specific QoS flow, and it is possible to suppress a decrease in performance of the entire mobile communication system 10.

[0119] Furthermore, even if the established QoS flow includes a Delay Critical GBR, by setting a scheduler #2 (223) for the Delay Critical GBR, the scheduler #2 (223) can execute scheduling for the Delay Critical GBR. As a result, since the one scheduler #2 (223) executes scheduling for the Delay Critical GBR, it is possible to suppress the influence on the Delay Critical GBR compared to the case where the scheduling is executed by all the schedulers 213, 223, and 233, and it is possible to suppress the deterioration of the performance of the entire mobile communication system 10.

[0120] Furthermore, as described above, each of the schedulers 213, 223, and 233 is configured to perform scheduling for each service such as eMBB, URLLC, and mMTC. This allows the scheduler to be set in consideration of network slices, enabling flexible system design.

[0121] Furthermore, if an established QoS flow is marked as "pre-emptable", the established QoS flow may be forcibly released. However, as described above, by having a specific scheduler 213, 223, or 233 perform a scheduling process for an established QoS flow, it is possible to suppress a decrease in performance of the entire system, and therefore it is also possible to suppress the forced release of a QoS flow.

[0122] [Other embodiments] In the above-mentioned operation example, the operation example when the UE 100 selects the URLLC service and when the URLLC service is terminated has been described. For example, even if the UE 100 selects the eMBB service or the mMTC service as a service other than the URLLC, the operation can be performed in the same manner. In this case, for example, when a QoS flow for the eMBB service is established, the CU 250 may select the DU #1 (212) having the scheduler #1 (213) for the eMBB for the QoS flow, and cause the scheduler #1 (213) to perform the scheduling process for the QoS flow. Also, for example, when a QoS flow for the mMTC service is established, the CU 250 may select the DU #3 (232) having the scheduler #2 (233) for the mMTC for the QoS flow, and cause the scheduler #2 (233) to perform the scheduling process for the QoS flow.

[0123] In addition, in the above-mentioned operation example, for example, the UE 100 can be implemented in the same manner even when the UE 100 selects any one of GBR, Non-GBR, and Delay Critical GBR (and terminates any one of GBR, Non-GBR, and Delay Critical GBR). That is, the UE 100 selects, for example, Delay Critical GBR, executes an application corresponding to the Delay Critical GBR, and transmits a PDU session establishment request including information on the Delay Critical GBR to the CN 300. After that, when the QoS flow for the Delay Critical GBR is established, the control unit 252 may select the DU #2 (222) having the scheduler #2 (223) for the Delay Critical GBR by the DU selection process (step S15). When the UE 100 terminates the service of the Delay Critical GBR, the DU #1 (212) included in the RAN #1 (210) to which the UE 100 was initially connected may be selected by the DU selection process (step S35) in the same manner as in the above-mentioned operation example.

[0124] A program for causing a computer to execute each process according to the above-described embodiment may be provided. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in the computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Such a recording medium may be included in the control unit 252 of the CU 250 and the control unit 2121 of the DU #1 (212). The control unit 252 of the CU 250 and the control unit 2121 of the DU #1 (212) may realize the functions described in the above-described embodiment by reading and executing the program from the recording medium. Therefore, the control unit 252 and the control unit 2121 may be a processor or controller such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor).

[0125] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like are possible without departing from the scope of the invention. In addition, the embodiments, operation examples, or processes can be combined within a range that does not contradict each other. [Explanation of symbols]

[0126] 10: Mobile communication system 100: UE 200:Base station (gNB) 210:RAN#1 211: RU#1 212: DU#1 213: Scheduler #1 220: RAN #2 221: RU#2 222: DU#2 223: Scheduler #2 230: RAN #3 231: RU#3 232: DU#3 233: Scheduler #3 250: CU 252: Control unit 300: CN

Claims

1. In a base station that wirelessly communicates with a user device, A first wireless unit and a second wireless unit capable of wirelessly communicating with the user equipment; a first distributed unit connected to the first wireless unit and including a first scheduler for a first service; a second distributed unit connected to the second wireless unit and including a second scheduler for a second service different from the first service; a control unit for controlling the first distribution unit and the second distribution unit, The control unit selects either the first distributed unit or the second distributed unit for an established QoS flow, and communicates with the user equipment.

2. The base station according to claim 1 , wherein the control unit selects the first distribution unit when the QoS flow is a QoS flow for the first service, and selects the second distribution unit when the QoS flow is a QoS flow for the second service.

3. The base station according to claim 1, wherein the control unit performs the selection in at least one of the following cases: when the user equipment makes an initial connection with the base station; when the user equipment selects the first service or the second service; and when the user equipment terminates the first service or the second service.

4. The base station according to claim 1 , wherein the first service is one of eMBB, URLLC, and mMTC, and the second service is one of eMBB, URLLC, and mMTC that is different from the first service.

5. 2. The base station according to claim 1, wherein the first service is any one of GBR, Non-GBR, and Delay Critical GBR, and the second service is any one of GBR, Non-GBR, and Delay Critical GBR that is different from the first service.

6. 2. The base station according to claim 1, wherein the control unit performs a first switching process to switch the connection of the user equipment from the first wireless unit to the second wireless unit when the user equipment is connected to the first wireless unit and selects the second distributed unit, and performs a second switching process to switch the connection of the user equipment from the second wireless unit to the first wireless unit when the user equipment is connected to the second wireless unit and selects the first distributed unit.

7. A QoS flow control method in a base station that performs wireless communication with a user device, the base station comprising: a first wireless unit and a second wireless unit capable of wireless communication with a user device; a first distributed unit connected to the first wireless unit and including a first scheduler for a first service; a second distributed unit connected to the second wireless unit and including a second scheduler for a second service different from the first service; and a controller that controls the first distributed unit and the second distributed unit, the QoS flow control method comprising: Selecting, by the control unit, either the first distribution unit or the second distribution unit for the established QoS flow and communicating with the user equipment. A QoS flow control method comprising:

Images