Radio access network node, core network node, radio terminal, and methods for these

Abstract

This radio access network (RAN) node (1) receives, from a core network (4), a first control message (201) that includes a first information element relating to a radio terminal (3). The first information element indicates at least one of the following: the volume of data that can be used by the radio terminal (3); and whether or not one or both of carrier aggregation and dual connectivity are required by the radio terminal (3), or whether or not one or both of carrier aggregation and dual connectivity are permitted in the radio terminal (3). This feature can, for example contribute to providing, to a RAN node, information that is useful for determining whether or not carrier aggregation (CA), dual connectivity (DC), or handovers are required by a radio terminal.

Description

Radio access network node, core network node, radio terminal, and methods thereof

[0001] The present disclosure relates to wireless communication systems, and more particularly to connection management or mobility management for wireless terminals.

[0002] In a fifth-generation mobile communication system (5G system), a Radio Access Network (RAN) can receive per Session Aggregate Maximum Bit Rate (Session-AMBR), per User Equipment (UE) Aggregate Maximum Bit Rate (UE-AMBR), and per UE per Slice-Maximum Bit Rate (UE-Slice-MBR) from a core network (see, for example, Non-Patent Documents 1 and 2). Each of Session-AMBR, UE-AMBR, and UE-Slice-MBR includes values ​​for uplink (UL) and downlink (DL).

[0003] The Session-AMBR limits the aggregate bit rate that can be provided across all non-Guaranteed Bit Rate (non-GBR) Quality of Service (QoS) Flows of a specific Protocol Data Unit (PDU) Session. The RAN uses the Session-AMBR to calculate its UE-AMBR.

[0004] The UE-AMBR limits the aggregate bit rate that can be provided across all Non-GBR QoS Flows of a wireless terminal (UE). The RAN enforces the UE-AMBR for each UE on both the UL and DL for Non-GBR QoS Flows. The RAN sets the UE-AMBR to the sum of the Session-AMBRs of all PDU Sessions with an active user plane for that RAN, up to the UE-AMBR received from the core network.

[0005] The UE-Slice-MBR limits the aggregate bit rate that can be provided across all GBR and non-GBR QoS Flows corresponding to the UE's PDU Sessions with active user planes in the same network slice (Single Network Slice Selection Assistance Information (S-NSSAI)). When a supporting RAN receives a UE-Slice-MBR for an S-NSSAI from the core network for a UE, the RAN applies this UE-Slice-MBR to all PDU Sessions with active user planes for that UE corresponding to that S-NSSAI, if feasible.

[0006] A Master Node (MN) of a Dual Connectivity (DC) can determine the Session-AMBR limit, UE-AMBR limit, and UE-Slice-MBR limit to be assigned to a Secondary Node (SN) of the DC, and send these to the SN (see, for example, Non-Patent Documents 3 and 4).

[0007] 3GPP TS 23.501 V17.4.0 (2022-03) "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 17)", March 2022 3GPP TS 38.413 V17.0.0 (2022-04) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; NG Application Protocol (NGAP) (Release 17)", April 2022 3GPP TS 37.340 V17.0.0 (2022-03) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and NR; Multi-connectivity; Stage 2 (Release 17)", March 2022 3GPP TS 38.423 V17.0.0 (2022-04) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Xn application protocol (XnAP) (Release 17)", April 2022

[0008] The inventors have considered Carrier Aggregation (CA), DC, and handover decisions by RAN nodes and have identified various challenges. One of these challenges relates to providing information to RAN nodes that is useful for determining whether CA, DC, or handover is required for a UE. Specifically, it may be desirable for the core network to be able to provide such information to RAN nodes.

[0009] Another problem the inventors have encountered relates to the use by a RAN node of a maximum bitrate parameter (e.g., Session-AMBR, UE-AMBR, or UE-Slice-MBR) provided by the core network to determine whether CA, DC, or handover is necessary. For example, if the UE-AMBR for a UE is changed or updated for some reason, the core network provides the RAN node with the updated UE-AMBR value. If the updated UE-AMBR value is small, the RAN node's initiation of a new DC for the UE or continuation of an ongoing DC may result in wasteful consumption of RAN computational and radio resources. Similar problems may arise when the Session-AMBR or UE-Slice-MBR is updated. Similar problems may also arise when CA is initiated or continued. Similar problems may also arise in the case of handover. For example, if the updated UE-AMBR value for a UE is small, moving the UE from a cell supporting high-speed communication to another cell may be beneficial in terms of efficient use of radio resources.

[0010] One of the objectives that the embodiments disclosed in this specification aim to achieve is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems, including the problems described above. It should be noted that this objective is only one of the objectives that the embodiments disclosed in this specification aim to achieve. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings.

[0011] In a first aspect, a radio access network node comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to receive a first control message from a core network containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.

[0012] In a second aspect, a method performed by a radio access network node includes receiving a first control message from a core network containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.

[0013] In a third aspect, a core network node comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to transmit a first control message to a radio access network node, the first control message including a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.

[0014] In a fourth aspect, a method performed by a core network node includes transmitting to a radio access network node a first control message containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.

[0015] In a fifth aspect, a wireless terminal comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to transmit a control message to a core network, the control message including an information element indicating whether or not carrier aggregation and / or dual connectivity is required.

[0016] In a sixth aspect, a method performed by a wireless terminal includes transmitting a control message to a core network, the control message including an information element indicating whether or not one or both of carrier aggregation and dual connectivity are required.

[0017] In a seventh aspect, a radio access network node comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to obtain one or more maximum bitrate parameters limiting an aggregate bitrate of multiple QoS flows for a wireless terminal, and the at least one processor configured to determine whether one or both of carrier aggregation and dual connectivity are required for the wireless terminal based on the one or more maximum bitrate parameters.

[0018] In an eighth aspect, a method performed by a radio access network node includes the steps of: (a) obtaining one or more maximum bitrate parameters that limit the aggregate bitrate of multiple QoS flows for a radio terminal; and (b) determining whether one or both of carrier aggregation and dual connectivity are required for the radio terminal based on the one or more maximum bitrate parameters.

[0019] In a ninth aspect, a radio access network node comprises at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to obtain one or more maximum bitrate parameters limiting an aggregate bitrate of a plurality of QoS flows for a wireless terminal, and the at least one processor configured to decide whether to handover the wireless terminal from a current serving cell to another cell based on the one or more maximum bitrate parameters.

[0020] In a tenth aspect, a method performed by a radio access network node includes the steps of: (a) obtaining one or more maximum bitrate parameters that limit the aggregate bitrate of multiple QoS flows for a wireless terminal; and (b) determining whether to handover the wireless terminal from a current serving cell to another cell based on the one or more maximum bitrate parameters.

[0021] In an eleventh aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform a method according to any of the above aspects.

[0022] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to CA, DC, and handover decisions by a RAN node, including the above-described problems.

[0023] 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an embodiment. FIG. 1 is a sequence diagram illustrating an example of signaling according to an embodiment. FIG. 2 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 3 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 4 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 5 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 6 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 7 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 8 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 9 is a sequence diagram illustrating an example of signaling according to an embodiment. FIG. 10 is a flowchart illustrating an example of an operation of a core network node according to an embodiment. FIG. 11 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 12 is a sequence diagram illustrating an example of an operation of a RAN node and a core network node according to an embodiment. FIG. 13 is a sequence diagram illustrating an example of an operation of two RAN nodes according to an embodiment. FIG. 14 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. FIG. 15 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment.

[0024] Hereinafter, 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 for clarity of explanation, duplicate explanations will be omitted as necessary.

[0025] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0026] The following embodiments will be described with the 3rd Generation Partnership Project (3GPP (registered trademark)) Long Term Evolution (LTE) system and the fifth generation mobile communication system (5G system) as the main targets. However, these embodiments may also be applied to other wireless communication systems that support 3GPP CA, DC, and handover-like technologies. The term LTE, as used in this specification, includes improvements and developments of LTE and LTE-Advanced to enable interworking with the 5G system, unless otherwise specified.

[0027] As used herein, depending on the context, "if" may be interpreted to mean "when," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be interpreted to have the same meaning, depending on the context.

[0028] First, the configurations and operations of multiple network elements common to multiple embodiments will be described. Figure 1 illustrates an example configuration of a wireless communication system according to multiple embodiments. In the example of Figure 1, the wireless communication system includes a RAN node 1, a RAN node 2, and a wireless terminal 3. Hereinafter, the wireless terminal 3 may be referred to as User Equipment (UE). Each element (network function) illustrated in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on the dedicated hardware, or as a virtualized function instantiated on an application platform.

[0029] The RAN node 1 may be a Central Unit (e.g., eNB-CU or gNB-CU) in a cloud RAN (C-RAN) deployment, or may be a combination of a CU and one or more Distributed Units (e.g., eNB-DUs or gNB-DUs). C-RAN is also referred to as a CU / DU split. Furthermore, a CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Thus, the RAN node 1 may be a CU-CP or a combination of a CU-CP and a CU-UP. Similarly, the RAN node 2 may be a CU or a combination of a CU and one or more DUs. The RAN node 2 may be a CU-CP or a combination of a CU-CP and a CU-UP.

[0030] Each of RAN nodes 1 and 2 may be an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (EUTRAN) node or a Next Generation Radio Access Network (NG-RAN) node. The EUTRAN node may be an eNB or an en-gNB. The NG-RAN node may be a gNB or an ng-eNB. The en-gNB provides NR user plane and control plane protocol terminations to the UE and operates as a secondary node (SN) for E-UTRA-NR Dual Connectivity (EN-DC). The ng-eNB provides E-UTRA user plane and control plane protocol terminations to the UE and is connected to the 5GC via the NG interface. The Radio Access Technology (RAT) of RAN node 1 may be different from that of RAN node 2.

[0031] RAN node 1 and RAN node 2 may communicate with each other via a node-to-node interface (i.e., X2 interface or Xn interface) 103. RAN node 1 and RAN node 2 may operate as a master node (MN) and a secondary node (SN), respectively, for dual connectivity. Hereinafter, RAN node 1 may be referred to as MN1, and RAN node 2 may be referred to as SN2. A radio terminal (UE) 3 may communicate with MN1 and SN2 via air interfaces 101 and 102 to perform dual connectivity for a master cell group (MCG) and a secondary cell group (SCG).

[0032] This dual connectivity may be Multi-Radio Dual Connectivity (MR-DC). MR-DC includes E-UTRA-NR Dual Connectivity (EN-DC), NG-RAN E-UTRA-NR Dual Connectivity (NGEN-DC), NR-E-UTRA Dual Connectivity (NE-DC), and NR-NR Dual Connectivity (NR-DC). Accordingly, the MN1 may be a master eNB (in EN-DC), a master ng-eNB (in NGEN-DC), or a master gNB (in NR-DC and NE-DC). Similarly, the SN2 may be an en-gNB (in EN-DC), a secondary ng-eNB (in NE-DC), or a secondary gNB (in NR-DC and NGEN-DC). In EN-DC, the UE3 is connected to an eNB operating as the MN1 and an en-gNB operating as the SN2. In NGEN-DC, UE3 is connected to an ng-eNB operating as MN1 and a gNB operating as SN2. In NE-DC, UE3 is connected to a gNB operating as MN1 and a ng-eNB operating as SN2. In NR-DC, UE3 is connected to one gNB (or gNB-DU) operating as MN1 and another gNB (or gNB-DU) operating as SN2.

[0033] The MCG is a group of serving cells associated with (or provided by) the MN1, and includes a Special Cell (SpCell) (i.e., a Primary Cell (PCell)) and, optionally, one or more Secondary Cells (SCells). On the other hand, the SCG is a group of serving cells associated with (or provided by) the SN2, and includes a Primary SCG Cell (PSCell) and, optionally, one or more Secondary Cells (SCells). A PSCell is an SpCell of the SCG, and supports Physical Uplink Control Channel (PUCCH) transmission and contention-based Random Access.

[0034] As used herein, the term "primary SCG cell" and its abbreviation "PSCell" refer to a cell included in a cell group provided by a dual connectivity SN, having an uplink component carrier, and configured with uplink control channel (e.g., PUCCH) resources. Specifically, the term "primary SCG cell" and its abbreviation "PSCell" may refer to the Primary SCG Cell of a cell group provided by an SN supporting 5G NR (e.g., en-gNB in ​​EN-DC, gNB in ​​NGEN-DC, or gNB in ​​NR-DC), or may refer to the Primary SC Cell of a cell group provided by an SN supporting E-UTRA (e.g., eNB in ​​LTE DC, or ng-eNB in ​​NE-DC).

[0035] RAN node 1 communicates with core network 4 via interface 104. RAN node 2 communicates with core network 4 via interface 105. Interface 104 includes a control plane interface (or connection) and a user plane interface (or connection). Interface 105 includes a user plane interface and may also include a control plane interface. The control plane interface may be an NG-C or S1-Mobility Management Entity (MME) interface. The user plane interface may be an NG-U or S1-U interface.

[0036] The core network 4 may be a 5G Core (5GC), an Evolved Packet Core (EPC), or a combination thereof. The core network 4 includes one or more core network nodes. These core network nodes include one or more control plane nodes and one or more user plane (or data plane) nodes. In a 5G system, the control plane nodes include an Access and Mobility Management Function (AMF), a Session Management Function (SMF), and other nodes (e.g., a Unified Data Management (UDM) and a Policy Control Function (PCF)), and the user plane nodes include a User Plane Function (UPF). In an LTE system, the control plane nodes include a Mobility Management Entity (MME) and other nodes (e.g., a Home Subscriber Server (HSS) and a Policy and Charging Rules Function (PCRF)), and the user plane nodes include a Serving Gateway (S-GW) and a Packet Data Network Gateway (P-GW).

[0037] The configuration example in FIG. 1 is an example and can be modified in various ways. For example, the MN and SN functions of dual connectivity may be provided by a single RAN node (e.g., RAN node 1). Specifically, the NR-DC can also be used when a UE 3 is connected only to a RAN node 1 (e.g., gNB) that operates as an MN and an SN and configures both an MCG and an SCG. In this case, the UE 3 may be connected to two gNB-DUs, one of which provides an MCG and the other provides an SCG, and these two gNB-DUs may be connected to a single gNB-CU that operates as both an MN and an SN. Alternatively, the UE 3 may be connected to a single gNB-DU that provides both an MCG and an SCG, and the gNB-DU may be connected to a single gNB-CU that operates as both an MN and an SN.

[0038] In this specification, the terms MN Radio Resource Control (RRC) Reconfiguration message and SN RRC Reconfiguration message are used. These terms are used for convenience to distinguish an RRC (Connection) Reconfiguration message generated by an MN from an RRC (Connection) Reconfiguration message generated by an SN. Therefore, an MN RRC Reconfiguration message may be simply referred to as an RRC Reconfiguration message or an RRC Connection Reconfiguration message. Similarly, an SN RRC Reconfiguration message may be simply referred to as an RRC Reconfiguration message or an RRC Connection Reconfiguration message.

[0039] First Embodiment This embodiment provides an improvement in signaling between a RAN and a core network, and an operation of the RAN based on the improved signaling. A configuration example of a wireless communication system according to this embodiment may be the same as the example shown in FIG.

[0040] 2 shows an example of signaling between the RAN node 1 and a core network node 5. The core network node 5 is a control plane node included in the core network 4. If the core network 4 is a 5GC, the core network node 5 may be an AMF or an SMF or a combination thereof, and the signaling may be NG Application Protocol (NGAP) signaling or messages. If the core network 4 is an EPC, the core network node 5 may be an MME, and the signaling may be S1AP signaling or messages.

[0041] In step 201, the core network node 5 sends a first control message to the RAN node 1, which contains a first information element related to the wireless terminal 3. The first control message may be an NGAP message or an S1AP message. The first information element indicates at least one of the following: the amount of data available to the wireless terminal 3; or whether CA and / or DC are required (or allowed) for the wireless terminal 3.

[0042] The core network node 5 may send a first control message including the first information element when a control connection for the radio terminal 3 is newly established between the core network node 5 and the RAN node 1. In this case, the first control message may be an NGAP: INITIAL CONTEXT SETUP REQUEST message. Additionally or alternatively, the core network node 5 may send a first control message including the updated first information element in response to updating or changing information included in the first information element. In this case, the first control message may be an NGAP: UE CONTEXT MODIFICATION REQUEST message. Additionally or alternatively, the core network node 5 may send a first control message including the first information element when a PDU Session for the radio terminal 3 is established. In this case, the first control message may be an NGAP: PDU SESSION RESOURCE SETUP REQUEST message.

[0043] The first information element may indicate at least the amount of data available to the wireless terminal 3. In this case, the name of the first information element may be, but is not limited to, a UE's Available Data information element. The information element may be an integer type and may have an integer value between 0 and 1,000,000,000,000 to indicate the size (bytes) of the data amount.

[0044] The amount of data available to the wireless terminal 3 may be the remaining amount of data available to a user (subscriber) of the wireless terminal 3 by the end of the current month. In other words, the amount of data available to the wireless terminal 3 may indicate the amount of data remaining up to a monthly data limit based on a contract (subscription). Alternatively, the amount of data available to the wireless terminal 3 may indicate the remaining amount of data that the user of the wireless terminal 3 can consume in a predetermined period (e.g., three days, one week, one month).

[0045] The first information element may at least indicate whether CA and / or DC are required (or permitted) for the wireless terminal 3. In this case, the name of the first information element may be, for example, but not limited to, an NR-DC / CA Enforceability information element. The information element may be an enumerated type and may indicate NR-DC & CA Enforceable, Only NR-DC Enforceable, Only CA Enforceable, or NR-DC & CA Not Enforceable.

[0046] In some implementations, depending on the communication status of the user of the wireless terminal 3, the core network node 5 may provide the RAN node 1 with a (updated) first information element indicating that one or both of CA and DC are not required or permitted for the wireless terminal 3. Specifically, if it is detected that the user of the wireless terminal 3 is about to use up the data capacity that can be used or consumed for a predetermined period (e.g., three days, one week, one month), the core network node 5 may provide the RAN node 1 with a (updated) first information element indicating that one or both of CA and DC are not required or permitted for the wireless terminal 3. Alternatively, if it is detected that the user of the wireless terminal 3 has used up the data capacity that can be used or consumed for a predetermined period (e.g., three days, one week, one month), the core network node 5 may provide the RAN node 1 with a (updated) first information element indicating that one or both of CA and DC are not required or permitted for the wireless terminal 3. On the other hand, if the data capacity available to the user of the wireless terminal 3 is restored, for example because a new predetermined period has begun, the core network node 5 may provide the RAN node 1 with an (updated) first information element indicating that one or both of CA and DC are required or permitted for the wireless terminal 3.

[0047] In some implementations, depending on other causes such as congestion in the core network 4, the core network node 5 may provide the RAN node 1 with an (updated) first information element indicating that one or both of CA and DC are not required or permitted for the radio terminal 3.

[0048] The first information element may be used by the RAN node 1 to determine whether CA and / or DC are required for the radio terminal 3. Specifically, the RAN node 1 may determine, based on or depending on the first information element, or using or taking into account the first information element, whether to perform or start one or both of CA and DC for the radio terminal 3. Additionally or alternatively, the RAN node 1 may determine, based on or depending on the first information element, or using or taking into account the first information element, whether to stop one or both of CA and DC that are currently being performed for the radio terminal 3.

[0049] CA may be initiated by adding or configuring one or more new SCells, or by activating one or more SCells that have already been added or configured. The addition and release of SCell(s) may be performed by the RAN node 1 sending an RRC (Connection) Reconfiguration message to the radio terminal 3. The activation of SCell(s) may be performed by the RAN node 1 sending an SCell Activation / Deactivation Medium Access Control (MAC) Control Element (CE) to the radio terminal 3.

[0050] The CA may be stopped by releasing one or more SCells, or by deactivating one or more SCells. The release of the SCell(s) may be performed by the RAN node 1 sending an RRC (Connection) Reconfiguration message to the radio terminal 3. The deactivation of the SCell(s) may be performed by the RAN node 1 sending an SCell Activation / Deactivation MAC CE to the radio terminal 3. The RAN node 1 may provide the radio terminal 3 with an updated measurement configuration via the RRC (Connection) Reconfiguration message so as to exclude the frequency of the released SCell(s) from the measurement target of the radio terminal 3.

[0051] The DC may be initiated by adding or configuring a new SN and SCG, or by activating an already added or configured SCG. The addition of an SN and SCG may be initiated by the MN (e.g., RAN node 1) initiating an SN Addition procedure. This SN Addition procedure includes transmitting an S-NODE ADDITION REQUEST message from the MN (e.g., RAN node 1) to the SN (e.g., RAN node 2). This SN Addition procedure further includes transmitting an MN RRC Reconfiguration message from the RAN node 1 to the radio terminal 3, the MN RRC Reconfiguration message including an SN RRC configuration message generated by the RAN node 2. The activation of the SCG may be performed by transmitting an RRC message, MAC CE, or Downlink Control Information (DCI) from the MN (e.g., RAN node 1) or SN (e.g., RAN node 2) to the radio terminal 3.

[0052] The DC may be stopped by releasing the SN and SCG or by deactivating the SCG. The release of the SN and SCG may be performed by the MN (e.g., RAN node 1) initiating an SN Release procedure. This SN Release procedure includes transmitting an S-NODE RELEASE REQUEST message from the MN (e.g., RAN node 1) to the SN (e.g., RAN node 2). In this SN Release procedure, if necessary, the MN (e.g., RAN node 1) may indicate to the radio terminal 3 via an MN RRC Reconfiguration message that the radio terminal 3 should release all SCG settings. The MN (e.g., RAN node 1) may provide updated measurement settings to the radio terminal 3 via an RRC (Connection) Reconfiguration message so as to exclude the frequencies of the released SCG from the measurement targets of the radio terminal 3.

[0053] In the SN Release procedure, the MN (e.g., RAN node 1) may include a Cause information element indicating the cause of the SN release in the S-NODE RELEASE REQUEST message. This Cause information element may be set to a value indicating, for example, that the wireless terminal 3 is about to use up the data amount based on the contract, or that the wireless terminal 3 has used up the data amount based on the contract. As an example, this Cause information element may be set to "UE Available Data Reaches Maximum."

[0054] Consider a case where the first information element indicates the amount of data available to the radio terminal 3. In this case, if the amount of data is below a first threshold, the RAN node 1 may determine or recognize that it will not perform (or will not start) one or both of CA and DC for the radio terminal 3. Similarly, if the amount of data is below the first threshold, the RAN node 1 may stop one or both of CA and DC currently being performed for the radio terminal 3. Conversely, if the amount of data exceeds a second threshold, the RAN node 1 may determine or recognize that it can perform (or start) one or both of CA and DC for the radio terminal 3. Similarly, if the amount of data exceeds the second threshold, the RAN node 1 may continue one or both of CA and DC currently being performed for the radio terminal 3. The second threshold may be the same as or different from the first threshold.

[0055] Consider a case where the first information element indicates whether CA and / or DC are required (or permitted) for the wireless terminal 3. In this case, if the first information element indicates that CA and / or DC are not required or prohibited, the RAN node 1 may determine or recognize that it will not perform (or will not start) CA and / or DC for the wireless terminal 3. Alternatively, the RAN node 1 may stop one or both of CA and DC currently being performed for the wireless terminal 3. Conversely, if the first information element indicates that CA and / or DC are required or permitted, the RAN node 1 may determine or recognize that it can perform (or start) one or both of CA and DC for the wireless terminal 3. Alternatively, the RAN node 1 may continue one or both of CA and DC currently being performed for the wireless terminal 3.

[0056] The first information element may be used by the RAN node 1 to decide whether to hand over the wireless terminal 3 from the current serving cell to another cell. Specifically, the RAN node 1 may decide whether to hand over the wireless terminal 3 based on or dependent on, or using or taking into account, the first information element.

[0057] Consider a case where the first information element indicates the amount of data available to the wireless terminal 3. In this case, if the amount of data is below a first threshold, the RAN node 1 may decide to handover the wireless terminal 3 from the current serving cell capable of high-speed communication to another cell. Conversely, if the amount of data exceeds a second threshold, the RAN node 1 may decide to handover the wireless terminal 3 from the current serving cell to another cell capable of high-speed communication. The second threshold may be the same as or different from the first threshold. For example, the cell capable of high-speed communication may be a cell operating in the millimeter wave (mmWave) (FR2) band, and the other cell may be a cell operating in the sub-6 GHz (FR1) band. Alternatively, the cell capable of high-speed communication may be a 5G New Radio (NR) cell, and the other cell may be an LTE cell.

[0058] The first information element may be used by the RAN node 1 to derive a second information element to be transmitted to the RAN node 2. Specifically, the RAN node 1 acting as the MN of the DC for the radio terminal 3 may derive the second information element based on the first information element and transmit a second control message including the second information element to the RAN node 2 acting as the SN of the DC. In one example, the RAN node 1 may separate the amount of data indicated in the first information element received from the core network node 5 into an amount of data allocated to the MN and an amount of data allocated to the SN. The RAN node 1 may then generate a second information element indicating the amount of data allocated to the SN and transmit a second control message including the second information element to the RAN node 2 acting as the SN. In another example, the RAN node 1 may transparently include the information indicated in the first information element received from the core network node 5 in the second information element. In other words, the RAN node 1 may include the information indicated in the first information element received from the core network node 5 in the second information element without any changes.

[0059] The signaling described with reference to FIG. 2 makes it possible to provide the RAN node 1 with information useful for deciding whether CA, DC or handover is required for the wireless terminal 3.

[0060] Figures 3 to 10 provide examples of the operation of RAN node 1, and Figures 11 and 12 provide examples of the operation of RAN node 2. In the following, examples of the operation of RAN nodes 1 and 2 will be described with reference to these figures.

[0061] Figure 3 shows an example of the operation of the RAN node 1. Step 301 corresponds to step 201 in Figure 2. Specifically, in step 301, the RAN node 1 receives a first control message from the core network 4, which includes a first information element related to the wireless terminal 3. The first information element indicates at least one of the following: the amount of data available to the wireless terminal 3; or whether CA and / or DC are required (or allowed) for the wireless terminal 3.

[0062] In step 302, the RAN node 1 determines, based on the first information element, whether one or both of CA and DC are required for the radio terminal 3. In other words, the RAN node 1 determines, based on or depending on the information provided in the first information element, or using or taking into consideration the information, whether one or both of CA and DC are required for the radio terminal 3. The method for this determination has already been described, and therefore a repeated description will be omitted here.

[0063] If DC is not needed for the wireless terminal 3, the RAN node 1 may operate not to start DC for the wireless terminal 3, or may stop a running DC for the wireless terminal 3. If CA is not needed for the wireless terminal 3, the RAN node 1 may operate not to start CA for the wireless terminal 3, or may stop a running CA for the wireless terminal 3.

[0064] 4 shows an example of the operation of the RAN node 1. Step 401 is similar to step 301 in FIG.

[0065] In step 402, the RAN node 1 determines, based on the first information element, whether to perform (or initiate) one or both of CA and DC for the radio terminal 3. In other words, the RAN node 1 determines, based on or depending on, or using or taking into consideration, the information provided in the first information element, whether to perform (or initiate) one or both of CA and DC for the radio terminal 3. The method for this determination has already been described, and therefore a repeated description will be omitted here.

[0066] Figure 5 shows an example of the operation of the RAN node 1. Step 501 is similar to step 301 in Figure 3. However, in step 501, while the RAN node 1 is performing CA for the wireless terminal 3, the RAN node 1 receives a first control message containing a first information element from the core network 4.

[0067] In step 502, the RAN node 1 determines whether to suspend the use of some or all of one or more SCells in the CA currently being performed for the radio terminal 3 based on the first information element. This determination method may be similar to any of the methods already described. Multiple thresholds may be used for this determination. Specifically, consider a case where the first information element indicates the amount of data available to the radio terminal 3. In this case, if the amount of data is below a first threshold, the RAN node 1 may release (or deactivate) some of the SCells configured (or activated) in the CA. If the amount of data is below a second threshold that is lower than the first threshold, the RAN node 1 may release (or deactivate) all of the SCells configured (or activated) in the CA.

[0068] Figure 6 shows an example of the operation of the RAN node 1. Step 601 is similar to step 301 in Figure 3. However, in step 601, while the RAN node 1 is performing DC for the radio terminal 3, the RAN node 1 receives a first control message containing a first information element from the core network 4.

[0069] In step 602, the RAN node 1 determines whether to stop using part or all of one or more SCGs of the DC currently running for the radio terminal 3 based on the first information element. This determination method may be similar to any of the methods already described. Multiple thresholds may be used for this determination. Specifically, consider a case where the first information element indicates the amount of data available to the radio terminal 3. In this case, if the amount of data falls below a first threshold, the RAN node 1 may release (or deactivate) some of the SCGs configured (or activated) in the DC. If the amount of data falls below a second threshold that is lower than the first threshold, the RAN node 1 may release (or deactivate) all SCGs configured (or activated) in the DC.

[0070] Figure 7 shows an example of the operation of the RAN node 1. Step 701 is similar to step 301 of Figure 3, except that in step 701 the first information element indicates at least the amount of data available to the wireless terminal 3.

[0071] In step 702, if the amount of data indicated in the first information element is below a first threshold, the RAN node 1 determines or recognizes that DC is not required for the wireless terminal 3. In step 703, if the amount of data indicated in the first information element is below a second threshold that is lower than the first threshold, the RAN node 1 determines or recognizes that neither DC nor CA is required for the wireless terminal 3. The order of steps 702 and 703 is not limited. Steps 702 and 703 may be performed substantially simultaneously, or step 703 may be performed before step 702.

[0072] Figure 8 shows an example of the operation of the RAN node 1. Step 801 is similar to step 301 in Figure 3. However, in step 801, while the RAN node 1 is performing one or both of CA and DC for the wireless terminal 3, the RAN node 1 receives a first control message containing a first information element from the core network 4. In addition, in step 801, the first information element indicates at least the amount of data available to the wireless terminal 3.

[0073] In step 802, if the amount of data indicated in the first information element is below a first threshold, the RAN node 1 stops one or both of CA and DC for the wireless terminal 3.

[0074] In step 803, the RAN node 1 does not initiate either or both of CA and DC for the radio terminal 3 until the amount of data exceeds a second threshold that is greater than the first threshold. In other words, the RAN node 1 stops either or both of CA and DC for the radio terminal 3 until it receives a new control message from the core network 4 indicating an updated value of the amount of data that exceeds the second threshold.

[0075] 9 shows an example of the operation of RAN node 1. Step 901 is similar to step 301 in FIG.

[0076] In step 902, the RAN node 1 decides based on the first information element whether to handover the wireless terminal 3 from the current serving cell to another cell, the method of this decision being similar to any of the methods already described.

[0077] 10 shows an example of the operation of the RAN node 1. Step 1001 is similar to step 301 in FIG.

[0078] In step 1002, the RAN node 1 acting as the MN sends a second control message including a second information element derived based on the first information element to the RAN node 2 acting as the SN of the DC for the wireless terminal 3. Note that the "RAN node 1 acting as the MN" may be a RAN node that can operate as an MN, i.e., an MN candidate before initiating DC. Alternatively, the "RAN node 1 acting as the MN" may be a RAN node operating as an MN after DC has been initiated. Similarly, the "RAN node 2 acting as the SN" may be a RAN node that can operate as an SN, i.e., an SN candidate before initiating DC. Alternatively, the "RAN node 2 acting as the SN" may be a RAN node that can operate as an SN after DC has been initiated. The method for deriving or generating the second information element may be the same as any of the methods already described. The second control message may be an XnAP message. More specifically, the second control message may be an XnAP: S-NODE ADDITION REQUEST message or an XnAP: S-NODE MODIFICATION REQUEST message.

[0079] 11 shows an example of the operation of the RAN node 2. In step 1101, the RAN node 2 acting as an SN of the DC receives a second control message containing a second information element related to the wireless terminal 3 from the RAN node 1 acting as an MN.

[0080] In step 1102, the RAN node 2 determines based on the second information element whether to suspend the use of some or all of one or more SCells of the CA running in the SCG for the radio terminal 3. The method of this determination may be similar to any of the methods already described for CA in the RAN node 1.

[0081] 12 shows an example of the operation of the RAN node 2. In step 1201, the RAN node 2 acting as an SN of the DC receives a second control message containing a second information element related to the wireless terminal 3 from the RAN node 1 acting as an MN.

[0082] In step 1202, the RAN node 2 determines whether to deactivate some or all of one or more SCGs of the DC running for the radio terminal 3 based on the second information element. The method of this determination may be the same as any of the methods already described for the DC in the RAN node 1. If it is determined to deactivate an SCG, the RAN node 2 may deactivate the SCG. Additionally or alternatively, if it is determined to deactivate an SCG, the RAN node 2 may request the RAN node 1 acting as the MN to release the SN.

[0083] Second Embodiment This embodiment provides a modification of the first embodiment. The configuration example of the wireless communication system according to this embodiment is the same as the example described with reference to FIG.

[0084] 13 shows an example of signaling between the wireless terminal 3 and the core network node 5. In step 1301, the wireless terminal 3 sends a control message including an information element indicating whether CA and / or DC is necessary to the core network node 5. The name of the information element may be, but is not limited to, a DC / CA Necessity information element.

[0085] If the core network 4 is a 5GC, the core network node 5 may be an AMF, an SMF, or a combination thereof. In this case, the control message in step 1301 may be a Non-Access Stratum (NAS) message. More specifically, the control message may be a REGISTRATION REQUEST message, a SERVICE REQUEST message, or a UL NAS TRANSPORT message sent from the radio terminal (UE) 3 to the AMF. Alternatively, the control message may be a PDU SESSION ESTABLISHMENT REQUEST message or a PDU SESSION MODIFICATION REQUEST message sent from the radio terminal (UE) 3 to the SMF. The PDU SESSION ESTABLISHMENT REQUEST message and the PDU SESSION MODIFICATION REQUEST message for session management are sent from the radio terminal 3 to the AMF via a UL NAS TRANSPORT message and forwarded to the SMF by the AMF.

[0086] The radio terminal 3 may transmit the control message of step 1301 (e.g., a REGISTRATION REQUEST message) when requesting registration to the core network 4. Additionally or alternatively, the radio terminal 3 may transmit the control message of step 1301 (e.g., a SERVICE REQUEST message) when requesting establishment of a secure connection with the AMF. Additionally or alternatively, the radio terminal 3 may transmit the control message of step 1301 (e.g., a UL NAS TRANSPORT message and a PDU SESSSION ESTABLISHMENT REQUEST message) when requesting establishment of a PDU Session.

[0087] The information element carried in the control message of step 1301 may be used by the core network node 5 to inform the RAN node 1 whether or not one or both of CA and DC are required or permitted for the radio terminal 3. More specifically, as shown in Fig. 14, the first information element described in the first embodiment may be determined or generated based on or depending on, or using or taking into account, an information element (e.g., DC / CA Necessity) received from the radio terminal 3.

[0088] Figure 14 shows an example of the operation of the core network node 5. Step 1401 corresponds to step 1301 in Figure 13. Specifically, the core network node 5 receives a control message including an information element indicating whether CA and / or DC is required from the radio terminal 3. In step 1402, the core network node 5 determines a first information element to be sent to the RAN node 1 based on the information element received from the radio terminal 3.

[0089] Specifically, if the information element from the radio terminal 3 indicates that CA is not required, the core network node 5 may provide the RAN node 1 with a first information element indicating that CA is not required or permitted for the radio terminal 3. Conversely, if the information element from the radio terminal 3 indicates that CA is required, the core network node 5 may provide the RAN node 1 with a first information element indicating that CA is required or permitted for the radio terminal 3.

[0090] Additionally or alternatively, if the information element from the radio terminal 3 indicates that DC is not required, the core network node 5 may provide the RAN node 1 with a first information element indicating that DC is not required or not permitted for the radio terminal 3. Conversely, if the information element from the radio terminal 3 indicates that DC is required, the core network node 5 may provide the RAN node 1 with a first information element indicating that DC is required or permitted for the radio terminal 3.

[0091] According to the signaling and the operations of the radio terminal 3 and the core network node 5 described in this embodiment, the radio terminal 3 can inform the core network node 5 of the necessity or non-necessity of either or both of CA and DC. The core network node 5 can inform the RAN node 1 of whether either or both of CA and DC are required (or permitted) for the radio terminal 3, taking into account the necessity or non-necessity of either or both of CA and DC indicated by the radio terminal 3.

[0092] Third Embodiment This embodiment provides an improvement in the operation of a RAN node. A configuration example of a wireless communication system according to this embodiment may be the same as the example shown in FIG.

[0093] Figure 15 shows an example of the operation of RAN node 1. The operation of Figure 15 may be performed by RAN node 2 operating as a DC SN for wireless terminal 3. In step 1501, RAN node 1 or 2 obtains one or more maximum bitrate parameters that limit the aggregate bitrate of multiple QoS Flows for wireless terminal 3. In step 1502, RAN node 1 or 2 determines whether one or both of CA and DC are required for wireless terminal 3 based on the one or more maximum bitrate parameters.

[0094] The one or more maximum bit rate parameters may include an Aggregate Maximum Bit Rate per wireless terminal, an Aggregate Maximum Bit Rate per PDU Session of the wireless terminal 3, or a Maximum Bit Rate per network slice of the wireless terminal 3, or any combination thereof. More specifically, the one or more maximum bit rate parameters may be a per User Equipment (UE) Aggregate Maximum Bit Rate (UE-AMBR), a per Session Aggregate Maximum Bit Rate (Session-AMBR), or a per UE per Slice-Maximum Bit Rate (UE-Slice-MBR), or any combination thereof. Each of the Session-AMBR, UE-AMBR, and UE-Slice-MBR includes values ​​for the uplink (UL) and downlink (DL).

[0095] The Session-AMBR limits the aggregate bit rate that can be provided across all non-GBR QoS Flows of a specific PDU Session. RAN node 1 uses the Session-AMBR to calculate its UE-AMBR.

[0096] The UE-AMBR limits the aggregate bit rate that can be provided across all Non-GBR QoS Flows of a radio terminal 3 (UE). The RAN node 1 enforces the UE-AMBR for Non-GBR QoS Flows on a per-UE basis in both the UL and DL. The RAN node 1 sets its UE-AMBR to the sum of the Session-AMBRs of all PDU Sessions with an active user plane for the RAN (e.g., RAN nodes 1 and 2), up to the UE-AMBR received from the core network 4.

[0097] The UE-Slice-MBR limits the aggregate bit rate that can be provided across all GBR and non-GBR QoS Flows corresponding to PDU Sessions with an active user plane of the radio terminal (UE) 3 in the same network slice (S-NSSAI). When the RAN node 1 receives a UE-Slice-MBR for an S-NSSAI for the radio terminal (UE) 3 from the core network 4, the RAN node 1 applies this UE-Slice-MBR to all PDU Sessions with an active user plane of the radio terminal (UE) 3 corresponding to that S-NSSAI, if feasible.

[0098] The RAN node 1 may receive one or more maximum bit rate parameters from the core network 4 via one or more control messages.

[0099] 16 is a sequence diagram showing an example of the operation of the RAN node 1 and the core network node 5. The core network node 5 is a control plane node included in the core network 4. If the core network 4 is a 5GC, the core network node 5 may be an AMF or an SMF or a combination thereof, and the signaling may be NG Application Protocol (NGAP) signaling or messages. If the core network 4 is an EPC, the core network node 5 may be an MME, and the signaling may be S1AP signaling or messages.

[0100] In step 1601, the RAN node 1 (e.g., gNB or ng-eNB) receives one or more maximum bit rate parameters from a core network node 5 (e.g., AMF or SMF) via one or more control messages. The one or more maximum bit rate parameters may be UE-AMBR, Session-AMBR, UE-Slice-MBR, or any combination thereof. Each of the one or more control messages may be an NGAP message. Specifically, each of the one or more control messages may be an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, a PDU SESSION RESOURCE SETUP REQUEST message, or a PDU SESSION RESOURCE MODIFY REQUEST message.

[0101] In step 1602, the RAN node 1 determines whether CA and / or DC is required for the wireless terminal 3 based on one or more maximum bit rate parameters received from the core network node 5.

[0102] In some implementations, the core network node 5 may provide the RAN node 1 with an updated UE-AMBR, Session-AMBR, UE-Slice-MBR, or any combination thereof, depending on the communication status of the user of the radio terminal 3. Specifically, if it is detected that the user of the radio terminal 3 is about to use up the data capacity that can be used or consumed in a predetermined period (e.g., three days, one week, one month), the core network 4 may update one or more of the UE-AMBR, Session-AMBR, and UE-Slice-MBR so that these values ​​decrease. Alternatively, if it is detected that the user of the radio terminal 3 has used up the data capacity that can be used or consumed in a predetermined period (e.g., three days, one week, one month), the core network 4 may update one or more of the UE-AMBR, Session-AMBR, and UE-Slice-MBR so that these values ​​decrease. On the other hand, if the data capacity available to the user of the wireless terminal 3 recovers due to reasons such as the entry of a new specified period, the core network 4 may update one or more of the UE-AMBR, Session-AMBR, and UE-Slice-MBR so that these values ​​become larger.

[0103] In some implementations, depending on other causes such as congestion in the core network 4, the core network node 5 may provide an updated UE-AMBR, Session-AMBR, UE-Slice-MBR, or any combination thereof to the RAN node 1.

[0104] The updating of the UE-AMBR, Session-AMBR, and UE-Slice-MBR may be performed by the PCF in the core network 4. The PCF may provide the updated UE-AMBR and updated UE-Slice-MBR to the AMF, and the updated Session-AMBR to the SMF.

[0105] 17 is a sequence diagram illustrating an example of the operation of RAN nodes 1 and 2. In step 1701, RAN node 1 (e.g., gNB or ng-eNB) sends one or more maximum bitrate parameters to RAN node 2 via one or more control messages. The one or more maximum bitrate parameters may be SN UE-AMBR, SN Session-AMBR, SN UE-Slice-MBR, or any combination thereof.

[0106] The SN UE-AMBR, SN Session-AMBR, and SN UE-Slice-MBR are determined by the RAN node 1 operating as the MN of the DC for the radio terminal 3. Specifically, the RAN node (MN) 1 separates the UE-AMBR received from the core network node 5 into a UE-AMBR upper limit to be assigned to the MN (i.e., MN UE-AMBR) and a UE-AMBR upper limit to be assigned to the SN (i.e., SN UE-AMBR), and notifies the RAN node (SN) 2 of the SN UE-AMBR. Similarly, the RAN node (MN) 1 separates the Session-AMBR received from the core network node 5 into a Session-AMBR upper limit to be assigned to the MN (i.e., MN Session-AMBR) and a Session-AMBR upper limit to be assigned to the SN (i.e., SN Session-AMBR), and notifies the RAN node (SN) 2 of the SN Session-AMBR. In addition, the RAN node (MN) 1 separates the UE-Slice-MBR received from the core network node 5 into a UE-Slice-MBR upper limit (i.e., MN UE-AMBR) to be allocated to the MN and a UE-Slice-MBR upper limit (i.e., SN UE-AMBR) to be allocated to the SN, and notifies the RAN node (SN) 2 of the SN UE-Slice-MBR.

[0107] Each of the one or more control messages of step 1701 may be an XnAP message. Specifically, each of the one or more control messages may be an S-NODE ADDITION REQUEST message or an S-NODE MODIFICATION REQUEST message.

[0108] In step 1702, RAN node 2 determines whether CA and / or DC are required for wireless terminal 3 based on one or more maximum bit rate parameters received from RAN node 1.

[0109] In some implementations, if the value of the UE-AMBR received from the core network 4 is below a first threshold, the RAN node 1 may determine or recognize that it will not perform (or will not start) one or both of CA and DC for the radio terminal 3. Similarly, if the UE-AMBR is below the first threshold, the RAN node 1 may stop one or both of CA and DC currently being performed for the radio terminal 3. For example, the RAN node 1 may stop using some or all of the SCell(s) or SCG(s) configured and activated for the radio terminal 3. Conversely, if the UE-AMBR exceeds a second threshold, the RAN node 1 may determine or recognize that it can perform (or start) one or both of CA and DC for the radio terminal 3. Similarly, if the UE-AMBR exceeds the second threshold, the RAN node 1 may continue one or both of CA and DC currently being performed for the radio terminal 3. The second threshold may be the same as or different from the first threshold.

[0110] In some implementations, if the value of the Session-AMBR received from the core network 4 or the value of the UE-AMBR calculated using the Session-AMBR is below a first threshold, the RAN node 1 may determine or recognize that one or both of CA and DC will not be performed (or will not be started) for the radio terminal 3. Similarly, if the Session-AMBR or the UE-AMBR is below the first threshold, the RAN node 1 may stop one or both of CA and DC currently being performed for the radio terminal 3. For example, the RAN node 1 may stop using some or all of the SCell(s) or SCG(s) configured and activated for the QoS Flow(s) of a PDU Session associated with a Session-AMBR below the first threshold. Conversely, if the Session-AMBR or the UE-AMBR is above a second threshold, the RAN node 1 may determine or recognize that one or both of CA and DC can be performed (or can be started) for the radio terminal 3. Similarly, if the Session-AMBR or UE-AMBR exceeds a second threshold, the RAN node 1 may continue one or both of the ongoing CA and DC for the wireless terminal 3. The second threshold may be the same as or different from the first threshold.

[0111] In some implementations, the RAN node 1 may determine or recognize that if the UE-Slice-MBR received from the core network 4 is below a first threshold, the RAN node 1 will not perform (or will not start) one or both of CA and DC for the radio terminal 3. Similarly, if the UE-Slice-MBR is below the first threshold, the RAN node 1 may stop one or both of CA and DC currently being performed for the radio terminal 3. For example, the RAN node 1 may stop using some or all of the SCell(s) or SCG(s) configured and activated for the QoS Flow(s) of the PDU Session(s) having an active user plane in the network slice associated with the UE-Slice-MBR below the first threshold. Conversely, if the UE-Slice-MBR is above a second threshold, the RAN node 1 may determine or recognize that it can perform (or start) one or both of CA and DC for the radio terminal 3. Similarly, if the UE-Slice-MBR exceeds a second threshold, the RAN node 1 may continue one or both of the ongoing CA and DC for the radio terminal 3. The second threshold may be the same as or different from the first threshold.

[0112] Similar to these operations of RAN node 1, RAN node 2 may use the SN UE-AMBR, SN Session-AMBR, or SN UE-Slice-MBR received from RAN node 1 to determine whether to execute, start, stop, or continue one or both of CA and DC for the radio terminal 3.

[0113] CA may be initiated by adding or configuring one or more new SCells, or by activating one or more SCells that have already been added or configured. The addition and release of SCell(s) may be performed by the RAN node 1 or 2 sending an RRC (Connection) Reconfiguration message to the radio terminal 3. The activation of SCell(s) may be performed by the RAN node 1 or 2 sending an SCell Activation / Deactivation MAC CE to the radio terminal 3.

[0114] The CA may be stopped by releasing one or more SCells, or by deactivating one or more SCells. The release of SCells may be performed by the RAN node 1 or 2 sending an RRC (Connection) Reconfiguration message to the radio terminal 3. The deactivation of SCells may be performed by the RAN node 1 or 2 sending an SCell Activation / Deactivation MAC CE to the radio terminal 3. The RAN node 1 or 2 may provide an updated measurement configuration to the radio terminal 3 via the RRC (Connection) Reconfiguration message so as to exclude the frequencies of the released SCell(s) from the measurement targets of the radio terminal 3.

[0115] The DC may be initiated by adding or configuring a new SN and SCG, or by activating an already added or configured SCG. The addition of an SN and SCG may be initiated by the MN (e.g., RAN node 1) initiating an SN Addition procedure. This SN Addition procedure includes transmitting an S-NODE ADDITION REQUEST message from the MN (e.g., RAN node 1) to the SN (e.g., RAN node 2). This SN Addition procedure further includes transmitting an MN RRC Reconfiguration message from the RAN node 1 to the radio terminal 3, the MN RRC Reconfiguration message including an SN RRC configuration message generated by the RAN node 2. The activation of the SCG may be performed by transmitting an RRC message, MAC CE, or Downlink Control Information (DCI) from the MN (e.g., RAN node 1) or SN (e.g., RAN node 2) to the radio terminal 3.

[0116] The DC may be stopped by releasing the SN and SCG or by deactivating the SCG. The release of the SN and SCG may be performed by the MN (e.g., RAN node 1) or the SN (e.g., RAN node 2) initiating an SN Release procedure. An SN Release procedure initiated by the MN includes transmitting an S-NODE RELEASE REQUEST message from the MN (e.g., RAN node 1) to the SN (e.g., RAN node 2). An SN Release procedure initiated by the SN includes transmitting an S-NODE RELEASE REQUIRED message from the SN (e.g., RAN node 2) to the MN (e.g., RAN node 1). In these SN Release procedures, the MN (e.g., RAN node 1) may, if necessary, indicate to the wireless terminal 3 in an MN RRC Reconfiguration message that the wireless terminal 3 should release all SCG settings. The MN (e.g., RAN node 1) may provide updated measurement configuration to the radio terminal 3 via an RRC (Connection) Reconfiguration message so as to exclude the frequencies of the released SCG from the measurement targets of the radio terminal 3.

[0117] In an SN Release procedure initiated by an MN, the MN (e.g., RAN node 1) may include a Cause information element indicating the cause of the SN release in an S-NODE RELEASE REQUEST message. Similarly, in an SN Release procedure initiated by an SN, the SN (e.g., RAN node 2) may include a Cause information element indicating the cause of the SN release in an S-NODE RELEASE REQUIRED message. This Cause information element may be set to a value indicating, for example, that the wireless terminal 3 is about to use up the data volume based on the contract, or that the wireless terminal 3 has used up the data volume based on the contract. As an example, this Cause information element may be set to "UE Available Data Reaches Maximum."

[0118] According to the operation of the RAN node 1 described with reference to Figures 15 and 16, the RAN node 1 can determine whether CA or DC is necessary for the radio terminal 3 by using a maximum bit rate parameter (e.g., UE-AMBR, Session-AMBR, UE-Slice-MBR, or any combination thereof) for the radio terminal 3 provided from the core network 4. For example, the RAN node 1 may stop DC for part or all of one or more PDU Sessions of the radio terminal 3 in response to a decrease in the UE-AMBR, Session-AMBR, or UE-Slice-MBR for the radio terminal 3. This can contribute to, for example, reducing unnecessary consumption of RAN computational resources and radio resources.

[0119] According to the operation of the RAN node 2 described with reference to Figures 15 and 17, the RAN node 2 can determine whether CA or DC is necessary for the wireless terminal 3 by using the maximum bit rate parameters (e.g., SN UE-AMBR, SN Session-AMBR, SN UE-Slice-MBR, or any combination thereof) for the wireless terminal 3 provided from the RAN node 1. For example, the RAN node 2 may stop DC for part or all of one or more PDU Sessions of the wireless terminal 3 in response to a decrease in the UE-AMBR, Session-AMBR, or UE-Slice-MBR for the wireless terminal 3. This can contribute to, for example, reducing unnecessary consumption of RAN computational resources and radio resources.

[0120] 18 to 23 provide examples of the operation of RAN nodes 1 and 2. In the following, examples of the operation of RAN nodes 1 and 2 will be described with reference to these figures.

[0121] 18 shows an example of the operation of RAN node 1 or 2. Step 1801 is similar to step 1501 in FIG.

[0122] In step 1802, the RAN node 1 or 2 determines, based on one or more maximum bit rate parameters, whether to perform (or start) one or both of CA and DC for the wireless terminal 3. In other words, the RAN node 1 or 2 determines, based on or depending on, or using or taking into consideration information about, one or more maximum bit rate parameters, whether to perform (or start) one or both of CA and DC for the wireless terminal 3. The method for this determination has already been described, and therefore a repeated description will be omitted here.

[0123] 19 shows an example of the operation of RAN node 1 or 2. Step 1901 is similar to step 1501 in FIG.

[0124] In step 1902, the RAN node 1 or 2 determines the number of SCells to be configured or activated in CA for the wireless terminal 3 based on one or more maximum bitrate parameters. The RAN node 1 or 2 may increase the number of SCells to be configured or activated as the value of the maximum bitrate parameter increases. In other words, the RAN node 1 or 2 may decrease the number of SCells to be configured or activated as the value of the maximum bitrate parameter decreases.

[0125] Figure 20 shows an example of the operation of RAN node 1 or 2. Step 2001 is similar to step 1501 in Figure 15. However, in step 2001, while RAN node 1 or 2 is performing CA for wireless terminal 3, RAN node 1 or 2 obtains one or more maximum bit rate parameters for wireless terminal 3.

[0126] In step 2002, the RAN node 1 or 2 determines whether to suspend the use of some or all of one or more SCells in the ongoing CA for the radio terminal 3 based on one or more maximum bitrate parameters. This determination method may be similar to any of the methods already described. Multiple thresholds may be used for this determination. Specifically, if the value of the maximum bitrate parameter is below a first threshold, the RAN node 1 or 2 may release (or deactivate) some of the SCells configured (or activated) in the CA. If the value of the maximum bitrate parameter is below a second threshold that is lower than the first threshold, the RAN node 1 or 2 may release (or deactivate) all of the SCells configured (or activated) in the CA.

[0127] Figure 21 shows an example of the operation of RAN node 1 or 2. Step 2101 is similar to step 1501 in Figure 15. However, in step 2101, while RAN nodes 1 and 2 are performing DC for wireless terminal 3, RAN node 1 or 2 obtains one or more maximum bit rate parameters for wireless terminal 3.

[0128] In step 2102, the RAN node 1 or 2 determines whether to stop using some or all of one or more SCGs of the DC currently running for the wireless terminal 3 based on one or more maximum bitrate parameters. This determination method may be similar to any of the methods already described. Multiple thresholds may be used for this determination. Specifically, if the value of the maximum bitrate parameter is below a first threshold, the RAN node 1 or 2 may release (or deactivate) some of the SCGs configured (or activated) in the DC. If the value of the maximum bitrate parameter is below a second threshold that is lower than the first threshold, the RAN node 1 or 2 may release (or deactivate) all SCGs configured (or activated) in the DC.

[0129] 22 shows an example of the operation of the RAN node 1. Step 2201 is similar to step 1501 in FIG.

[0130] In step 2202, if the value of the maximum bitrate parameter is below a first threshold, the RAN node 1 determines or recognizes that DC is not required for the wireless terminal 3. In step 2203, if the value of the maximum bitrate parameter is below a second threshold that is lower than the first threshold, the RAN node 1 determines or recognizes that neither DC nor CA is required for the wireless terminal 3. The order of steps 2202 and 2203 is not limited. Steps 2202 and 2203 may be performed substantially simultaneously, or step 2203 may be performed before step 2202.

[0131] Figure 23 shows an example of the operation of the RAN node 1. Step 2301 is similar to step 1501 in Figure 15. However, in step 2301, while the RAN node 1 is performing one or both of CA and DC for the wireless terminal 3, the RAN node 1 obtains a maximum bit rate parameter.

[0132] In step 2302, if the value of the maximum bitrate parameter is below a first threshold, the RAN node 1 stops one or both of CA and DC for the wireless terminal 3.

[0133] In step 2303, the RAN node 1 does not start either or both of CA and DC for the wireless terminal 3 until the value of the maximum bitrate parameter exceeds a second threshold that is greater than the first threshold. In other words, the RAN node 2 stops either or both of CA and DC for the wireless terminal 3 until it obtains an updated value of the maximum bitrate parameter that exceeds the second threshold.

[0134] Fourth Embodiment This embodiment provides an improvement in the operation of a RAN node. A configuration example of a wireless communication system according to this embodiment may be the same as the example shown in FIG.

[0135] 24 shows an example of the operation of the RAN node 1. In step 2401, the RAN node 1 obtains one or more maximum bitrate parameters that limit the aggregate bitrate of multiple QoS Flows for the radio terminal 3. Specific examples of the one or more maximum bitrate parameters may be the same as those described in the third embodiment. Specifically, the one or more maximum bitrate parameters may be UE-AMBR, Session-AMBR, or UE-Slice-MBR, or any combination thereof. The RAN node 1 may receive the one or more maximum bitrate parameters from the core network 4 via one or more control messages.

[0136] In step 2402, the RAN node 1 determines whether to handover the wireless terminal 3 from the current serving cell to another cell based on one or more maximum bit rate parameters. For example, if the value of the maximum bit rate parameter is below a first threshold, the RAN node 1 may determine to handover the wireless terminal 3 from the current serving cell capable of high-speed communication to another cell. Conversely, if the value of the maximum bit rate parameter is above a second threshold, the RAN node 1 may determine to handover the wireless terminal 3 from the current serving cell to another cell capable of high-speed communication. The second threshold may be the same as or different from the first threshold. For example, the cell capable of high-speed communication may be a cell operating in the mmWave (FR2) band, and the other cell may be a cell operating in the sub-6 GHz (FR1) band. Alternatively, the cell capable of high-speed communication may be a 5G New Radio (NR) cell, and the other cell may be an LTE cell.

[0137] According to the operation of the RAN node 1 described with reference to FIG. 24 , the RAN node 1 can determine whether or not handover of the radio terminal 3 is necessary by using the maximum bit rate parameters (e.g., UE-AMBR, Session-AMBR, UE-Slice-MBR, or any combination thereof) for the radio terminal 3 provided from the core network 4.

[0138] Next, exemplary configurations of the RAN nodes 1 and 2, the radio terminal 3, and the core network node 5 according to the above-described embodiments will be described below. FIG. 25 is a block diagram showing an exemplary configuration of the RAN node 1. The configurations of other RAN nodes 2 may also be similar to the configuration shown in FIG. 25. Referring to FIG. 25, the RAN node 1 includes a radio frequency transceiver 2501, a network interface 2503, a processor 2504, and a memory 2505. The RF transceiver 2501 performs analog RF signal processing for communication with UEs, including the UE 3. The RF transceiver 2501 may include multiple transceivers. The RF transceiver 2501 is coupled to an antenna array 2502 and a processor 2504. The RF transceiver 2501 receives modulation symbol data from the processor 2504, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 2502. The RF transceiver 2501 also generates a baseband receive signal based on the receive RF signal received by the antenna array 2502 and supplies the baseband receive signal to the processor 2504. The RF transceiver 2501 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0139] The network interface 2503 is used to communicate with network nodes (e.g., other RAN nodes as well as nodes within the core network 4). The network interface 2503 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0140] The processor 2504 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 2504 may include multiple processors. For example, the processor 2504 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing.

[0141] For example, digital baseband signal processing by processor 2504 may include signal processing for 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. Also, control plane processing by processor 2504 may include processing of Non-Access Stratum (NAS) messages, RRC messages, MAC Control Elements (CEs), and Downlink Control Information (DCI).

[0142] The processor 2504 may include a digital beamformer module for beamforming, which may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0143] The memory 2505 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 2505 may include storage located remotely from the processor 2504. In this case, the processor 2504 may access the memory 2505 via the network interface 2503 or an I / O interface (not shown).

[0144] The memory 2505 may store one or more software modules (computer programs) 2506 including instructions and data for performing the processes of the RAN node 1 described in the above embodiments. In some implementations, the processor 2504 may be configured to read and execute the software modules 2506 from the memory 2505 to perform the processes of the RAN node 1 described in the above embodiments.

[0145] The control plane processing and operations performed by the RAN node 1 described in the above embodiments may be realized by a processor 2504 and a memory 2505 storing software modules 2506.

[0146] If the RAN node 1 is a CU (e.g., eNB-CU or gNB-CU) or a CU-CP, the RAN node 1 may not include an RF transceiver 2501 (and antenna array 2502).

[0147] 26 is a block diagram showing an example configuration of a wireless terminal 3. A radio frequency (RF) transceiver 2601 performs analog RF signal processing for communication with RAN nodes 1 and 2. The RF transceiver 2601 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 2601 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 2601 is coupled to an antenna array 2602 and a baseband processor 2603. The RF transceiver 2601 receives modulation symbol data (or OFDM symbol data) from the baseband processor 2603, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 2602. The RF transceiver 2601 also generates a baseband receive signal based on the receive RF signal received by the antenna array 2602 and provides the baseband receive signal to the baseband processor 2603. The RF transceiver 2601 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0148] The baseband processor 2603 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0149] For example, the digital baseband signal processing by the baseband processor 2603 may include signal processing of the SDAP layer, PDCP layer, RLC layer, MAC layer, and PHY layer. Also, the control plane processing by the baseband processor 2603 may include processing of the Non-Access Stratum (NAS) protocol, the RRC protocol, MAC CEs, and DCIs.

[0150] The baseband processor 2603 may perform MIMO encoding and precoding for beamforming.

[0151] The baseband processor 2603 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 2604, which will be described later.

[0152] The application processor 2604 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 2604 may include multiple processors (multiple processor cores). The application processor 2604 executes a system software program (operating system (OS)) and various application programs (e.g., a call application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 2606 or a memory not shown, thereby realizing various functions of the wireless terminal 3.

[0153] In some implementations, the baseband processor 2603 and the application processor 2604 may be integrated on a single chip, as shown by the dashed line (2605) in Figure 26. In other words, the baseband processor 2603 and the application processor 2604 may be implemented as a single System on Chip (SoC) device 2605. An SoC device is sometimes called a system Large Scale Integration (LSI) or chipset.

[0154] The memory 2606 is volatile memory, nonvolatile memory, or a combination thereof. The memory 2606 may include multiple physically independent memory devices. The volatile memory is, for example, SRAM, DRAM, or a combination thereof. The nonvolatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. For example, the memory 2606 may include an external memory device accessible from the baseband processor 2603, the application processor 2604, and the SoC 2605. The memory 2606 may also include an internal memory device integrated within the baseband processor 2603, the application processor 2604, or the SoC 2605. Furthermore, the memory 2606 may include memory within a Universal Integrated Circuit Card (UICC).

[0155] The memory 2606 may store one or more software modules (computer programs) 2607 including instructions and data for performing the processing by the wireless terminal 3 described in the above-described embodiments. In some implementations, the baseband processor 2603 or the application processor 2604 may be configured to read and execute the software modules 2607 from the memory 2606, thereby performing the processing by the wireless terminal 3 described in the above-described embodiments using the drawings.

[0156] The control plane processing and operations performed by the wireless terminal 3 described in the above embodiment can be realized by elements other than the RF transceiver 2601 and the antenna array 2602, namely, at least one of the baseband processor 2603 and the application processor 2604, and the memory 2606 storing the software module 2607.

[0157] 27 shows an example of the configuration of the core network node 5. With reference to FIG. 27, the core network node 5 includes a network interface 2701, a processor 2702, and a memory 2703.

[0158] The network interface 2701 is used, for example, to communicate with other network functions (NFs) or nodes, and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0159] The processor 2702 may be, for example, a microprocessor, an MPU, or a CPU. The processor 2702 may include multiple processors.

[0160] The memory 2703 is composed of volatile memory and nonvolatile memory. The memory 2703 may include multiple physically independent memory devices. The volatile memory is, for example, SRAM or DRAM, or a combination thereof. The nonvolatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. The memory 2703 may include storage located remotely from the processor 2702. In this case, the processor 2702 may access the memory 2703 via the network interface 2701 or the I / O interface.

[0161] The memory 2703 may store one or more software modules (computer programs) 2704 including instructions and data for performing the processing by the core network node 5 described in the above embodiments. In some implementations, the processor 2702 may be configured to read and execute the software modules 2704 from the memory 2703, thereby performing the processing by the core network node 5 described in the above embodiments.

[0162] As described with reference to Figures 25, 26, and 27, each of the processors included in the RAN nodes 1 and 2, the radio terminal 3, and the core network node 5 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example, and not limitation, transitory computer-readable or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0163] Furthermore, the above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0164] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0165] (Supplementary Note 1) A radio access network node comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to receive from a core network a first control message containing a first information element related to a radio terminal, wherein the first information element indicates at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 2) The radio access network node of Supplementary Note 1, wherein the first information element at least indicates whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 3) The radio access network node of Supplementary Note 1, wherein the first information element indicates at least an amount of data available to the radio terminal, the amount of data being a remaining amount of data available to a user of the radio terminal by the end of the current month. (Supplementary Note 4) The radio access network node according to any one of Supplements 1 to 3, wherein the at least one processor is configured to determine, based on the first information element, whether to perform one or both of carrier aggregation and dual connectivity for the radio terminal. (Supplementary Note 5) The radio access network node according to any one of Supplements 1 to 3, wherein the at least one processor is configured to determine, based on the first information element, whether to stop using a part or all of one or more secondary cells of ongoing carrier aggregation for the radio terminal. (Supplementary Note 6) The radio access network node according to any one of Supplements 1 to 3, wherein the at least one processor is configured to determine, based on the first information element, whether to stop using a part or all of one or more secondary cell groups of ongoing dual connectivity for the radio terminal.(Supplementary Note 7) The radio access network node according to any one of Supplements 1 to 3, wherein the at least one processor is configured to transmit a second control message to a secondary node of dual connectivity for the radio terminal, the second control message including a second information element derived based on the first information element. (Supplementary Note 8) The radio access network node according to Supplementary Note 7, wherein the second information element is used by the secondary node to determine whether to stop using a part or all of one or more secondary cells of ongoing carrier aggregation in a secondary cell group for the radio terminal. (Supplementary Note 9) The radio access network node according to Supplementary Note 7, wherein the second information element is used by the secondary node to determine whether to stop using a part or all of one or more secondary cell groups of ongoing dual connectivity for the radio terminal. (Supplementary Note 10) The radio access network node according to any one of Supplements 1 to 3, wherein the at least one processor is configured to decide whether to handover the radio terminal from a current serving cell to another cell based on the first information element. (Supplementary Note 11) The radio access network node according to Supplementary Note 1 or 3, wherein the at least one processor is configured to recognize that dual connectivity is not required for the radio terminal if the amount of data is below a first threshold, and the at least one processor is configured to recognize that neither dual connectivity nor carrier aggregation is required for the radio terminal if the amount of data is below a second threshold that is lower than the first threshold.(Supplementary Note 12) The radio access network node according to any one of Supplements 1, 3 and 11, wherein the at least one processor is configured to stop one or both of carrier aggregation and dual connectivity for the radio terminal if the amount of data is below a third threshold, and the at least one processor is configured not to start one or both of carrier aggregation and dual connectivity for the radio terminal until the amount of data exceeds a fourth value that is greater than the third threshold. (Supplementary Note 13) The radio access network node according to any one of Supplements 1 to 12, wherein the first control message is an NG Application Protocol (NGAP) message, and the first control message is an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, or a PDU SESSION RESOURCE SETUP REQUEST message. (Supplementary Note 14) The radio access network node according to any one of Supplementary Notes 7 to 9, wherein the second control message is an Xn Application Protocol (XnAP) message, and the second control message is an S-NODE ADDITION REQUEST message or an S-NODE MODIFICATION REQUEST message. (Supplementary Note 15) A method performed by a radio access network node, comprising receiving a first control message from a core network, the first control message including a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.(Supplementary Note 16) A program causing a computer to perform a method for a radio access network node, the method comprising receiving from a core network a first control message containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 17) A core network node comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to send to a radio access network node a first control message containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 18) The core network node according to Supplementary Note 17, wherein the first information element at least indicates whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 19) The core network node according to Supplementary Note 17, wherein the first information element at least indicates an amount of data available to the radio terminal, the amount of data being a remaining amount of data available to a user of the radio terminal by the end of the current month. (Supplementary Note 20) The core network node according to any one of Supplements 17 to 19, wherein the first information element is used by the radio access network node to determine whether to perform one or both of carrier aggregation and dual connectivity for the radio terminal. (Supplementary Note 21) The core network node according to any one of Supplements 17 to 19, wherein the first information element is used by the radio access network node to determine whether to stop using some or all of one or more secondary cells for ongoing carrier aggregation for the radio terminal.(Supplementary Note 22) The core network node according to any one of Supplements 17 to 19, wherein the first information element is used by the radio access network node to stop use of part or all of one or more secondary cell groups of ongoing dual connectivity for the radio terminal. (Supplementary Note 23) The core network node according to any one of Supplements 17 to 19, wherein the first information element is used by the radio access network node to decide whether to hand over the radio terminal from a current serving cell to another cell. (Supplementary Note 24) The core network node according to any one of Supplements 17 to 23, wherein the at least one processor is configured to receive from the radio terminal a second control message including an information element indicating whether one or both of carrier aggregation and dual connectivity are required, and wherein the at least one processor is configured to determine the first information element based on the information element received from the radio terminal. (Supplementary Note 25) The core network node according to any one of Supplementary Notes 17 to 24, wherein the first control message is an NG Application Protocol (NGAP) message, and the first control message is an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, or a PDU SESSION RESOURCE SETUP REQUEST message. (Supplementary Note 26) A method performed by a core network node, comprising: transmitting to a radio access network node a first control message containing a first information element related to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal.(Supplementary Note 27) A program causing a computer to perform a method for a core network node, the method comprising transmitting a first control message to a radio access network node, the first information element relating to a radio terminal, the first information element indicating at least one of: an amount of data available to the radio terminal; or whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 28) A radio terminal comprising: at least one memory; and at least one processor coupled to the at least one memory and configured to transmit a control message to a core network, the control message including an information element indicating whether one or both of carrier aggregation and dual connectivity are required or allowed. (Supplementary Note 29) The radio terminal of Supplementary Note 28, wherein the information element is used by the core network to inform a radio access network node whether one or both of carrier aggregation and dual connectivity are required or allowed for the radio terminal. (Supplementary Note 30) The wireless terminal according to Supplementary Note 28 or 29, wherein the control message is a Non-Access-Stratum (NAS) message, and the control message is a REGISTRATION REQUEST message, a SERVICE REQUEST message, a UL NAS TRANSPORT message, a PDU SESSION ESTABLISHMENT REQUEST message, or a PDU SESSION MODIFICATION REQUEST message. (Supplementary Note 31) A method performed by a wireless terminal, comprising transmitting, to a core network, a control message including an information element indicating whether one or both of carrier aggregation and dual connectivity are required. (Supplementary Note 32) A method for causing a computer to perform a method for a wireless terminal, comprising transmitting, to a core network, a control message including an information element indicating whether one or both of carrier aggregation and dual connectivity are required.(Supplementary Note 33) A radio access network node comprising: at least one memory; and at least one processor coupled to the at least one memory, wherein the at least one processor is configured to: obtain one or more maximum bitrate parameters limiting an aggregate bitrate of a plurality of Quality of Service (QoS) flows for a radio terminal; and determine whether one or both of carrier aggregation and dual connectivity are required for the radio terminal based on the one or more maximum bitrate parameters. (Supplementary Note 34) The radio access network node of Supplementary Note 33, wherein the determining comprises determining whether to perform dual connectivity for the radio terminal based on the one or more maximum bitrate parameters. (Supplementary Note 35) The radio access network node of Supplementary Note 33, wherein the determining comprises determining whether to perform carrier aggregation for the radio terminal based on the one or more maximum bitrate parameters. (Supplementary Note 36) The radio access network node of Supplementary Note 33, wherein the determining comprises determining a number of secondary cells to be configured or activated in carrier aggregation for the radio terminal based on the one or more maximum bit rate parameters. (Supplementary Note 37) The radio access network node of Supplementary Note 33, wherein the determining comprises determining whether to stop using some or all of one or more secondary cells of ongoing carrier aggregation for the radio terminal based on the one or more maximum bit rate parameters. (Supplementary Note 38) The radio access network node of Supplementary Note 33, wherein the determining comprises determining whether to stop using some or all of one or more secondary cell groups of ongoing dual connectivity for the radio terminal based on the one or more maximum bit rate parameters.(Supplementary Note 39) The radio access network node of Supplementary Note 33, wherein the at least one processor is configured to recognize that dual connectivity is not required for the wireless terminal if one of the one or more maximum bit rate parameters is below a first threshold, and the at least one processor is configured to recognize that neither dual connectivity nor carrier aggregation is required for the wireless terminal if the one maximum bit rate parameter is below a second threshold that is lower than the first threshold. (Supplementary Note 40) The radio access network node according to Supplementary Note 33, wherein the at least one processor is configured to stop one or both of carrier aggregation and dual connectivity for the radio terminal if one of the one or more maximum bit rate parameters is below a third threshold, and wherein the at least one processor is configured not to start one or both of carrier aggregation and dual connectivity for the radio terminal until the one maximum bit rate parameter exceeds a fourth value that is greater than the third threshold. (Supplementary Note 41) The radio access network node according to any one of Supplementary Notes 33 to 40, wherein the one or more maximum bit rate parameters include an Aggregate Maximum Bit Rate per radio terminal, an Aggregate Maximum Bit Rate per PDU Session of the radio terminal, or a Maximum Bit Rate per network slice of the radio terminal, or any combination thereof. (Supplementary Note 42) The radio access network node according to any one of Supplementary Notes 33 to 40, wherein the one or more maximum bit rate parameters comprise a per User Equipment Aggregate Maximum Bit Rate (UE-AMBR), a per Session Aggregate Maximum Bit Rate (Session-AMBR), or a per UE per Slice-Maximum Bit Rate (UE-Slice-MBR), or any combination thereof.(Supplementary Note 43) The radio access network node according to any one of Supplements 33 to 42, wherein the obtaining of the one or more maximum bit rate parameters comprises receiving the one or more maximum bit rate parameters from a core network via one or more control messages. (Supplementary Note 44) The radio access network node according to Supplementary Note 43, wherein each of the one or more control messages is an NG Application Protocol (NGAP) message, and each of the one or more control messages is an INITIAL CONTEXT SETUP REQUEST message, a UE CONTEXT MODIFICATION REQUEST message, a PDU SESSION RESOURCE SETUP REQUEST message, or a PDU SESSION RESOURCE MODIFY REQUEST message. (Supplementary Note 45) The radio access network node according to any one of Supplements 33, 35 to 38 and 40, wherein the obtaining of the one or more maximum bitrate parameters comprises receiving the one or more maximum bitrate parameters from a dual connectivity master node via one or more control messages. (Supplementary Note 46) The radio access network node according to Supplementary Note 45, wherein the control message is an Xn Application Protocol (XnAP) message, and the control message is an S-NODE ADDITION REQUEST message or an S-NODE MODIFICATION REQUEST message. (Supplementary Note 47) A method performed by a radio access network node comprising: obtaining one or more maximum bitrate parameters limiting an aggregate bitrate of a plurality of Quality of Service (QoS) flows for a wireless terminal, and determining whether one or both of carrier aggregation and dual connectivity are required for the wireless terminal based on the one or more maximum bitrate parameters.(Supplementary Note 48) A program for causing a computer to perform a method for a radio access network node, the method comprising: obtaining one or more maximum bitrate parameters that limit an aggregate bitrate of a plurality of Quality of Service (QoS) flows for a radio terminal; and determining whether one or both of carrier aggregation and dual connectivity are required for the radio terminal based on the one or more maximum bitrate parameters. (Supplementary Note 49) A radio access network node comprising: at least one memory; and at least one processor coupled to the at least one memory, wherein the at least one processor is configured to: obtain one or more maximum bitrate parameters that limit an aggregate bitrate of a plurality of Quality of Service (QoS) flows for a radio terminal; and determine whether to handover the radio terminal from a current serving cell to another cell based on the one or more maximum bitrate parameters. (Supplementary Note 50) The radio access network node according to Supplementary Note 49, wherein the one or more maximum bit rate parameters comprise an Aggregate Maximum Bit Rate per radio terminal, an Aggregate Maximum Bit Rate per PDU Session of the radio terminal, or a Maximum Bit Rate per network slice of the radio terminal, or any combination thereof. (Supplementary Note 51) The radio access network node according to Supplementary Note 49 or 50, wherein the obtaining of the one or more maximum bit rate parameters comprises receiving the one or more maximum bit rate parameters from a core network via one or more control messages.(Supplementary Note 52) A method performed by a radio access network node, comprising: obtaining one or more maximum bitrate parameters that limit the aggregate bitrate of a plurality of Quality of Service (QoS) flows for a radio terminal, and determining whether to hand over the radio terminal from a current serving cell to another cell based on the one or more maximum bitrate parameters. (Supplementary Note 53) A program for causing a computer to perform a method for a radio access network node, the method comprising: obtaining one or more maximum bitrate parameters that limit the aggregate bitrate of a plurality of Quality of Service (QoS) flows for a radio terminal, and determining whether to hand over the radio terminal from a current serving cell to another cell based on the one or more maximum bitrate parameters.

[0166] This application claims priority based on Japanese Patent Application No. 2022-090224, filed on June 2, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0167] REFERENCE SIGNS LIST 1 RAN node 2 RAN node 3 Radio terminal 4 Core network 5 Core network node 2504 Processor 2505 Memory 2506 Modules 2603 Baseband processor 2604 Application processor 2606 Memory 2607 Modules 2702 Processor 2703 Memory 2704 Modules

Claims

1. A method for receiving a first control message from a core network, the first control message including a first information element related to a wireless terminal, The first information element is the amount of data available to the wireless terminal; or Whether carrier aggregation and / or dual connectivity is required or permitted for the wireless terminal; A radio access network node, which indicates at least one of:

2. The method further comprises: determining whether to perform one or both of carrier aggregation and dual connectivity for the wireless terminal based on the first information element. A radio access network node according to claim 1.

3. The method further comprises: determining whether to stop using a part or all of one or more secondary cells of an ongoing carrier aggregation for the wireless terminal based on the first information element. A radio access network node according to claim 1.

4. The method further comprises: determining whether to stop using a part or all of one or more secondary cell groups of an ongoing dual connectivity for the wireless terminal based on the first information element. A radio access network node according to claim 1.

5. The method further comprises: means for transmitting a second control message including a second information element derived based on the first information element to a secondary node of dual connectivity for the wireless terminal. A radio access network node according to claim 1.

6. Means for recognizing that dual connectivity is not required for the wireless terminal if the amount of data is below a first threshold; and and means for recognizing that neither dual connectivity nor carrier aggregation is required for the wireless terminal if the amount of data is below a second threshold that is less than the first threshold. A radio access network node according to claim 1.

7. receiving a first control message from a core network containing a first information element relating to the wireless terminal; The first information element is the amount of data available to the wireless terminal; or Whether carrier aggregation and / or dual connectivity is required or permitted for the wireless terminal; Indicate at least one of A method performed by a radio access network node.

8. A program for causing a computer to perform a method for a radio access network node, comprising: The method comprises receiving a first control message from a core network containing a first information element related to a wireless terminal; The first information element is the amount of data available to the wireless terminal; or Whether carrier aggregation and / or dual connectivity is required or permitted for the wireless terminal; A program showing at least one of the following:

9. Means for transmitting a first control message to a radio access network node, the first control message including a first information element relating to a wireless terminal, The first information element is the amount of data available to the wireless terminal; or Whether carrier aggregation and / or dual connectivity is required or permitted for the wireless terminal; A core network node indicating at least one of:

10. A means for transmitting a control message including an information element indicating whether or not one or both of carrier aggregation and dual connectivity are required to a core network. Wireless terminal.