Communication method, node, and user equipment

Abstract

To solve the problem that there is a fear of increase in a load of a master node in a mobile communication system.SOLUTION: A communication method for a user apparatus UE to perform wireless communication with a master node MN and a plurality of secondary nodes SN in the mobile communication system comprises: a step of performing, by the master node, a process of delegating to at least one of the plurality of secondary nodes a control right to perform, on the user apparatus, configuration and / or control related to a cooperative operation between the plurality of secondary nodes; and a step of performing, by the secondary node to which the control right is delegated, configuration and / or control related to the cooperative operation for the user apparatus.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a communication method, a node, and a user equipment for use in a mobile communication system. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark; the same applies below)), a standardization project for mobile communication systems, defines technical specifications for dual connectivity (DC). In DC, a user equipment (UE) performs wireless communication with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN). In DC, the roles of nodes that communicate with the UE are divided between MN and SN. Except for settings that are determined independently by the SN, the MN has the initiative (also called "control authority") to configure and control the UE.

[0003] In each of the MCG and SCG, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated, and the UE can simultaneously receive or transmit on multiple CCs (i.e., multiple cells). The multiple CCs may be contiguous or non-contiguous in the frequency direction. One serving cell in each of the MCG and SCG is called a primary cell (PCell), and a set of serving cells is formed by configuring one or more secondary cells (SCells) in the UE together with the PCell. The PCell (SpCell) of the SCG is also called a primary secondary cell (PSCell).

[0004] In the current 3GPP technical specifications, a UE uses only one SN in a DC. On the other hand, Non-Patent Document 1 describes multi-connectivity in which a UE uses multiple SNs (i.e., multiple SCGs) simultaneously. However, such multi-connectivity raises concerns that the load on the MN may increase because the MN configures and / or controls multiple SNs. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP contribution RWS-210143 “Multi Radio Multi Connectivity for Rel-18” Summary of the Invention

[0006] A communication method according to a first aspect is a communication method in a mobile communication system for a user device to perform wireless communication with a master node and a plurality of secondary nodes, the method including the steps of: the master node performing a process of delegating control authority for configuring and / or controlling the cooperative operation between the plurality of secondary nodes for the user device to at least one of the plurality of secondary nodes; and the secondary node to which the control authority has been delegated performs configuration and / or control regarding the cooperative operation for the user device.

[0007] A node according to a second aspect is a node that operates as a master node in a mobile communication system in which a user device performs wireless communication with a master node and a plurality of secondary nodes, and is provided with a control unit that performs processing to delegate control authority for configuring and / or controlling cooperative operation between the plurality of secondary nodes for the user device to at least one of the plurality of secondary nodes.

[0008] A node according to a third aspect is a node that operates as a secondary node in a mobile communication system in which a user equipment performs wireless communication with a master node and a plurality of secondary nodes, and is provided with a control unit that, when control authority for configuring and / or controlling the cooperative operation between the plurality of secondary nodes is delegated to the user equipment from the master node, performs configuration and / or control of the cooperative operation for the user equipment.

[0009] A user device according to a fourth aspect is a user device that performs wireless communication with a master node and a plurality of secondary nodes, and is equipped with a wireless communication unit that receives a signal for setting and / or controlling the cooperative operation between the plurality of secondary nodes from a secondary node to which the master node has delegated control authority to perform setting and / or control regarding the cooperative operation between the plurality of secondary nodes for the user device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack of a U-plane radio interface that handles data. [Diagram 3] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack of a C-plane wireless interface that handles signaling (control signals). [Figure 4] 1 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment. [Diagram 5] FIG. 2 is a diagram for explaining dual connectivity (DC) according to an embodiment. [Figure 6] FIG. 1 is a diagram showing an example of an LTM procedure according to an embodiment. [Figure 7] FIG. 2 is a diagram illustrating a configuration example of a node (base station) according to the embodiment. [Figure 8] FIG. 2 is a diagram illustrating a configuration example of a UE (user equipment) according to the embodiment. [Figure 9] FIG. 2 is a diagram for explaining an operation scenario of the mobile communication system according to the first embodiment. [Figure 10] FIG. 2 is a diagram showing an overview of the operation of the mobile communication system according to the first embodiment. [Figure 11] FIG. 2 is a diagram showing an example of the operation of the mobile communication system according to the first embodiment. [Figure 12] FIG. 11 is a diagram showing a modified example of the operation of the mobile communication system according to the first embodiment. [Figure 13]FIG. 11 is a diagram for explaining an operation scenario of the mobile communication system according to the second embodiment. [Figure 14] FIG. 11 is a diagram showing an example of the operation of the mobile communication system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] (1) First embodiment The first embodiment will be described with reference to FIGS.

[0013] (1.1) System configuration example Fig. 1 is a diagram showing a configuration example of a mobile communication system according to a first embodiment. The mobile communication system according to the first embodiment is a system that complies with the 3GPP standard. For example, the mobile communication system according to the first embodiment may be a fifth generation (5G) system or a sixth generation (6G) system.

[0014] The mobile communication system includes a network (NW) 1 and a user equipment (UE) 100. The UE 100 is a mobile communication device that performs wireless communication with the NW 1. The UE 100 may be any device used by a user, and may be, for example, a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC (Personal Computer), a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0015] The NW1 includes a radio access network (RAN) 10 and a core network (CN) 20. When the mobile communication system is a 5th generation system (5GS: 5th Generation System), the RAN 10 is referred to as a Next Generation Radio Access Network (NG-RAN), and the CN 20 is referred to as a 5G Core Network (5GC).

[0016] The RAN 10 includes a plurality of nodes 200 (nodes 200a to 200c in the illustrated example). The nodes 200 are connected to each other via inter-node interfaces. The nodes 200 are also referred to as base stations. The nodes 200 are configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and both units may be connected by a fronthaul interface. When the mobile communication system is 5GS, the nodes 200 are referred to as gNBs, the inter-node interface is referred to as an Xn interface, and the fronthaul interface is referred to as an F1 interface.

[0017] Each node 200 manages one or more cells. The node 200 performs wireless communication with the UE 100 that has established a connection with its own cell. Each node 200 has a radio resource management (RRM) function, a routing function for user data (also simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. Note that "cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency (also simply referred to as "frequency").

[0018] The CN 20 includes a CN device 300. The CN device 300 may include a C-plane device corresponding to a control plane (C-plane) and a U-plane device corresponding to a user plane (U-plane). The C-plane device performs various mobility controls and paging for the UE 100. The C-plane device communicates with the UE 100 using NAS (Non-Access Stratum) signaling. The U-plane device performs data transfer control. When the mobile communication system is 5GS, the C-plane device is called an AMF (Access and Mobility Management Function), the U-plane device is called a UPF (User Plane Function), and the interface between the node 200 and the CN device 300 is called an NG interface.

[0019] FIG. 2 is a diagram showing an example of the configuration of a protocol stack of a U-plane radio interface that handles data.

[0020] The U-plane radio interface protocol includes, for example, a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0021] The PHY layer performs coding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the node 200 via a physical channel. The PHY layer of the UE 100 receives downlink control information (DCI) transmitted from the node 200 on a physical downlink control channel (PDCCH). Specifically, the UE 100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to the UE. The DCI transmitted from the node 200 has CRC parity bits scrambled by the RNTI added thereto.

[0022] The MAC layer performs data priority control and retransmission processing using hybrid ARQ (HARQ), etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the node 200 via a transport channel. The MAC layer of the node 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to the UE 100.

[0023] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the node 200 via logical channels.

[0024] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0025] The SDAP layer performs mapping between an IP flow, which is a unit for QoS control by the CN 20, and a radio bearer, which is a unit for QoS control by an AS (Access Stratum). Note that if the RAN is connected to the EPC, the SDAP is not necessary.

[0026] FIG. 3 is a diagram showing an example of the configuration of a protocol stack of a C-plane wireless interface that handles signaling (control signals).

[0027] The protocol stack of the C-plane radio interface has, for example, a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) layer instead of the SDAP layer shown in FIG.

[0028] Between the RRC layer of the UE 100 and the RRC layer of the node 200, RRC signaling for various settings is transmitted. The RRC layer controls logical channels, transport channels, and physical channels in response to establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in an RRC idle state. When the connection between the RRC of the UE 100 and the RRC of the node 200 is suspended, the UE 100 is in an RRC inactive state.

[0029] The NAS layer (also simply referred to as "NAS") located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of UE 100 and the NAS layer of CN device 300. Note that UE 100 has an application layer and the like in addition to the radio interface protocol. Also, the layer below the NAS layer is referred to as the AS layer (also simply referred to as "AS").

[0030] (1.2) DC using a terahertz wave cell FIG. 4 is a diagram for explaining the terahertz (THz) wave cell according to the first embodiment.

[0031] The mobile communication system according to the first embodiment may be a 6G system. In 6G, it is expected that terahertz (THz) waves will be utilized. A cell operated by THz waves is called a THz wave cell. Compared with millimeter waves (mmW), THz waves have a stronger tendency to travel in a straight line, have a higher free space loss, and are more susceptible to the effects of the atmosphere and precipitation. Therefore, the THz wave cell may be an ultra-small cell.

[0032] In the illustrated example, the diameter of the coverage area of ​​the THz wave cell is about 10 [m], the diameter of the coverage area of ​​the mmW cell operated at mmW is about 100 [m], and the diameter of the coverage area of ​​the macro cell is about 1000 [m]. Under such assumptions, for example, UE 100 moving at 60 [km / s] passes through the coverage area of ​​each THz wave cell in about 599 [ms].

[0033] Dual connectivity (DC) is one of the methods for stably controlling small cells in mobile communication systems.

[0034] 5 is a diagram for explaining dual connectivity (DC) according to the first embodiment. In the first embodiment, it is assumed that a THz-wave cell is used as a cell of a secondary cell group (SCG). Furthermore, a THz-wave cell may be used as a secondary cell (SCell) of a master cell group (MCG). However, a mmW cell may be used instead of the THz-wave cell.

[0035] A DC may be set for the UE 100 in the RRC connected state. In the DC, the UE 100 performs radio communication with a master cell group (MCG) managed by a master node (MN) 200M and a secondary cell group (SCG) managed by a secondary node (SN). The MN 200M and the SN 200S are connected to each other via an inter-node interface. When the MN 200M and the SN 200S are not distinguished from each other, they are simply referred to as the node 200. When the MN 200M is a 5G / NR node, it is also referred to as a master gNB (MgNB). When the SN 200M is a 5G / NR node, it is also referred to as a secondary gNB (SgNB). Except for the settings determined independently by the SN 200S, the MN 200M has the initiative (control authority) to set and control the UE 100.

[0036] For example, the MN 200M transmits a predetermined message (e.g., an SN Addition Request message) to the SN 200S, and the MN 200M transmits an RRC Reconfiguration message to the UE 100, whereby the SCG is set in the UE 100 and DC is started. In the DC, the UE 100 in the RRC connected state is assigned radio resources by the respective schedulers of the MN 200M and the SN 200S, and performs radio communication using the radio resources of the MN 200M and the radio resources of the SN 200S.

[0037] The MN 200M may have a control plane connection with the CN 20. The MN 200M provides the main radio resources of the UE 100. The MN 200M manages the MCG, which is a group of serving cells associated with the MN 200M. The MCG has a primary cell (PCell) and optionally has one or more secondary cells (SCells). On the other hand, the SN 200S may not have a control plane connection with the CN 20. The SN 200S provides additional radio resources to the UE 100. The SN 200S manages the SCG, which is a group of serving cells associated with the SN 200S. The SCG has a primary / secondary cell (PSCell) and optionally has one or more SCells. The PCell of the MCG and the PSCell of the SCG may be referred to as a special cell (SpCell).

[0038] In the current 3GPP technical specifications, the UE 100 uses only one SN 200S in DC. That is, the UE 100 cannot use multiple SNs 200S simultaneously. On the other hand, in the first embodiment, multi-connectivity in which the UE 100 uses multiple SNs 200S (that is, multiple SCGs) simultaneously is assumed.

[0039] (1.3) Overview of LTM The mobile communication system according to the first embodiment supports LTM (L1 / L2-triggered mobility).

[0040] LTM is a technique for reducing mobility delay compared to a general handover procedure by triggering cell switching by signaling of lower layers, Layer 1 (L1) and / or Layer 2 (L2). In LTM, first, the node 200 prepares an LTM candidate cell configuration for a candidate cell to be switched to, and provides the LTM candidate cell configuration to the UE 100 by RRC signaling. Second, the node 200 receives a Layer 1 (L1) measurement report from the UE 100, and transmits a cell switch command indicating the LTM candidate cell configuration to the UE 100 by a MAC CE (Control Element) based on the L1 measurement report. The cell switch trigger is conveyed in the MAC CE including at least a candidate configuration index together with a beam indicator. Third, the UE 100 changes the serving cell in response to the cell switch command. In this way, the node 200 triggers cell switching by selecting the LTM candidate cell configuration as a target configuration. The LTM candidate cell configuration can be added, modified, and released by the node 200 via RRC signaling.

[0041] The following principles apply to LTM:

[0042] Each LTM candidate cell configuration can be provided as a differential configuration (delta configuration) relative to a reference configuration that is used to form the complete candidate cell configuration.

[0043] A full candidate cell configuration is applied, replacing the current UE configuration during a cell switch. A reconfiguration procedure involves replacement but does not necessarily reset the MAC, RLC or PDCP layers.

[0044] The user plane continues without a reset if configured in RRC signalling to avoid additional delays in data recovery.

[0045] -Security is not updated in LTM.

[0046] LTM between subsequent LTM candidate cell configurations can be performed without RRC reconfiguration, i.e., the UE 100 does not release other LTM candidate cell configurations after LTM is triggered.

[0047] In the first embodiment, a scenario is assumed in which the PSCell of the UE 100 is changed between the SNs 200S by using LTM. Details of such a scenario will be described later.

[0048] 6 is a diagram showing an example of an LTM procedure according to the first embodiment. In the illustrated example, it is assumed that the UE 100 performs cell switching from a first cell of the node 200 to a second cell of the node 200. Here, the first cell and the second cell may be configured by different TRPs (Transmission and Reception Points).

[0049] In step S11, the UE 100 is in an RRC connected state in the cell of the node 200.

[0050] In step S12, the UE 100 transmits a Measurement Report message, which is an RRC message, to the node 200.

[0051] In step S13, the node 200 decides to use LTM based on the Measurement Report message and starts candidate cell preparation.

[0052] In step S14, the node 200 transmits, to the UE 100, an RRC Reconfiguration message including an LTM candidate cell configuration of one or more candidate cells.

[0053] In step S15, the UE 100 saves the LTM candidate cell configuration and transmits an RRC Reconfiguration Complete message to the node 200.

[0054] In step S16, the UE 100 may perform downlink (DL) synchronization and timing advance (TA) acquisition with the candidate cell before receiving the cell switch command.

[0055] In step S17, the UE 100 performs Layer 1 (L1) measurement in the configured candidate cell, and transmits a lower layer measurement report (L1 Measurement Report) to the node 200. The L1 Measurement Report may be transmitted and received at L1, which is a PHY layer. The L1 Measurement Report may be transmitted and received at Layer 2 (L2), which includes a MAC layer, an RLC layer, and a PDCP layer. Note that the order of steps S16 and S17 may be reversed.

[0056] In step S18, the node 200 decides to perform cell switching to the target cell (second cell).

[0057] In step S19, the node 200 transmits to the UE 100 a Cell Switch Command (MAC CE) including a candidate configuration index of the target cell.

[0058] In step S20, the UE 100 switches to the configuration of the target cell. Specifically, the UE 100 detaches from the source cell (first cell) and applies the configuration of the target cell.

[0059] In step S21, if the cell switching needs to include the execution of a random access procedure, the UE 100 executes a random access procedure for the target cell. Note that, if the UE 100 does not need to acquire the TA of the target cell at the time of the cell switching, the random access procedure may be skipped.

[0060] In step S22, the UE 100 indicates that the cell switch to the target cell has been successfully completed. The UE 100 may then perform steps S16 to S22 multiple times for subsequent LTM cell switches based on the configuration provided in step S14.

[0061] (1.4) Node configuration example 7 is a diagram showing a configuration example of the node 200 (base station) according to the first embodiment. The node 200 may be an MN 200M or an SN 200S.

[0062] The node 200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a NW communication unit 240. The transmitting unit 210 and the receiving unit 220 configure a wireless communication unit 250 that performs wireless communication with the UE 100.

[0063] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The receiving unit 220 performs various receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230.

[0064] The control unit 230 performs various controls and processes in the node 200. The operations of the node 200 described above and below may be operations under the control of the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0065] The NW communication unit 240 is connected to adjacent nodes via an inter-node interface. The NW communication unit 240 is connected to the CN device 300 via a node-CN interface.

[0066] The node 200 configured in this manner may operate as the MN 200M when the UE 100 performs wireless communication (i.e., multi-connectivity) with the MN 200M and multiple SNs 200S. In the first embodiment, the control unit 230 of the node 200 operating as the MN 200M performs control so as to delegate to at least one of the multiple SNs 200S the control authority for performing setting and / or control regarding the cooperative operation between the multiple SNs 200S for the UE 100.

[0067] Alternatively, the node 200 may operate as the SN 200S when the UE 100 performs wireless communication (i.e., multi-connectivity) with the MN 200M and a plurality of SNs 200S. In the first embodiment, the control unit 230 of the node 200 operating as the SN 200S performs settings and / or control for the cooperative operation of the UE 100 when the control authority for performing settings and / or control for the UE 100 regarding the cooperative operation among the plurality of SNs 200S is delegated from the MN 200M.

[0068] (1.5) Example of user device settings FIG. 8 is a diagram showing an example of the configuration of the UE 100 (user device) according to the first embodiment.

[0069] The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 configure a wireless communication unit 140 that performs wireless communication with the node 200.

[0070] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the signal to the control unit 130. The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 130 into a radio signal and transmits the signal from the antenna.

[0071] The control unit 130 performs various controls and processes in the UE 100. The above and below described operations of the UE 100 may be operations under the control of the control unit 230. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0072] The UE 100 configured in this manner may perform wireless communication (i.e., multi-connectivity) with the MN 200M and multiple SNs 200S. The wireless communication unit 140 (receiving unit 110) of the UE 100 receives a wireless signal for setting and / or controlling the cooperative operation from the SN 200S to which the control authority for setting and / or controlling the cooperative operation between the multiple SNs 200S is delegated from the MN 200M to the UE 100.

[0073] (1.6) System operation example FIG. 9 is a diagram for explaining an operation scenario of the mobile communication system according to the first embodiment.

[0074] In the illustrated example, the UE 100 performs wireless communication by multi-connectivity with the MN 200M and multiple SNs 200S (SNs 200S#1 and SNs 200S#2). Each SN 200S has a narrower cell coverage than the MN 200M. Specifically, each SN 200S (SCG) is operated at a higher frequency than the MN 200M (MCG). For example, the MN 200M (MCG) may be operated in the Sub-6 band, and each SN 200S (SCG) may be operated in the THz band or mmW band. In the first embodiment, a scenario in which each SN 200S (SCG) is operated in the THz band is mainly assumed.

[0075] In such a scenario in which the cell coverage of each SN200S (SCG) is narrow, it is preferable to perform multi-connectivity by setting multiple SCGs in the UE100 and to switch between SCGs as the UE100 moves. However, in such multi-connectivity, the MN200 needs to perform setting and / or control for multiple SN200S, and there is a concern that the load on the MN200M will increase. In other words, in multi-connectivity, if the MN200M manages all the control like DC, the load on the MN200M will increase significantly, which is not preferable. In the first embodiment, the load on the MN200M is reduced by transferring authority from the MN200M to the SN200S.

[0076] FIG. 10 is a diagram showing an overview of the operation of the mobile communication system according to the first embodiment.

[0077] In step S1, the MN 200M delegates to at least one of the multiple SNs 200S a control authority for performing configuration and / or control regarding cooperative operation between the multiple SNs 200S for the UE 100. For example, the MN 200M transmits a first message for requesting cooperative operation between the multiple SNs 200S to at least one of the multiple SNs 200S.

[0078] In step S2, the SN 200S to which the control authority has been delegated performs settings and / or control regarding cooperative operation among the plurality of SNs 200S for the UE 100. The SN 200S that has received the first message from the MN 200M may transmit a second message for starting cooperative operation among the plurality of SNs 200S to other SNs 200S included in the plurality of SNs 200S.

[0079] This makes it possible to suppress an increase in the load on the MN 200M even when multi-connectivity is performed.

[0080] In the first embodiment, the cooperative operation between the multiple SNs 200S is a cell switching operation for switching between the SNs 200S the serving cell of the UE 100. That is, the MN 200M transfers authority to perform mobility control of the UE 100 between the SNs 200S.

[0081] In the first embodiment, a scenario is assumed in which a cell switching operation (mobility control) is performed by the above-mentioned LTM. Specifically, in the first embodiment, after setting cells (TRPs) of a plurality of SN200S in the UE100, the PSCell of the UE100 is changed between the SN200S by using LTM. In such a scenario, there is a concern that each SN200S does not know with which SN200S it should perform cooperative operation (TRP cooperative operation), but in the first embodiment, the combination of SN200S that should perform cooperative operation can be specified by the above-mentioned first message and / or second message.

[0082] Fig. 11 is a diagram showing an example of the operation of the mobile communication system according to the first embodiment. In Fig. 11, non-essential steps are indicated by dashed lines.

[0083] In step S101, the UE 100 performs wireless communication using dual connectivity (DC) with the MN 200M and the SN 200S#1.

[0084] In step S102, the UE 100 may transmit a Measurement Report message including a measurement result of the radio quality of each cell to the MN 200M. The MN 200M may receive the Measurement Report message from the UE 100.

[0085] In step S103, the MN200M determines a combination of SN200S to be operated in cooperation with each other. For example, the MN200M identifies a cell whose wireless quality satisfies a predetermined condition based on the Measurement Report message in step S102, and determines the SN200S to which the identified cell belongs. Here, it is assumed that the MN200M has determined the SN200S#2 as the SN200S to be operated in cooperation with the SN200S#1. The MN200M may determine the SN200S#2 as the SN200S to be operated in cooperation with the SN200S#1 based on the combination of SN200S (or combination of cells) set by the network operator (OAM: Operation Administration and Management). In the first embodiment, the MN200M may determine the cell of the SN200S#1 as the source cell of the LTM, and may determine the cell of the SN200S#2 as the candidate cell (or target cell) of the LTM.

[0086] In step S104, the MN 200M transmits an S-node Pairing Request message, which is a request message (first message) for cooperation, to the SN 200S#1. In the illustrated example, the MN 200M transmits the S-node Pairing Request message to the SN 200S#1, but the MN 200M may transmit the S-node Pairing Request message to the SN 200S#2, or may transmit the S-node Pairing Request message to both the SN 200S#1 and the SN 200S#2. In the first embodiment, the S-node Pairing Request message may be a request message requesting a PSCell change of the UE 100 between the SNs 200S using LTM.

[0087] In the illustrated example, the request message for cooperation (first message) is a new message transmitted and received on an inter-node interface, but the request message for cooperation (first message) may be an existing message (e.g., an S-NODE MODIFICATION REQUEST message) defined in the 3GPP technical specifications. The request message for cooperation (first message) may be a request message (e.g., an S-node Xn Establishment Request message) requesting establishment of an inter-node interface between SN200S.

[0088] The request message for a coordinated action (first message) includes at least one piece of information among the following items 1) to 5).

[0089] 1) Identifier of the target UE 100: The request message for cooperation (first message) may include, for example, an identifier of the UE 100 on the inter-node interface (such as an Xn-AP UE ID).

[0090] 2) Identifier of the target SN200S: The request message for cooperation (first message) may include, for example, the node ID of the target SN 200S, in particular, the ID of the SN 200S to be paired with.

[0091] 3) Identification of the cell of interest (e.g., source cell or candidate cell): The request message for cooperation (first message) includes, for example, the NCGI (NR Cell Global Identifier) ​​of the target cell, in particular, the cell ID of the cell to be paired.

[0092] 4) Information indicating the type of cooperative action to be performed: The request message for cooperative operation (first message) includes, for example, information indicating the type of cooperative operation to be performed (PSCell change using LTM between SNs 200S in the first embodiment).

[0093] 5) Total UE context of UE 100: The request message for cooperation (first message) may include, for example, a full UE context as transmitted in an existing Handover Request message, rather than a partial UE context as transmitted in an existing S-NODE ADDITION REQUEST message.

[0094] Thus, the request message for cooperative operation (first message) includes at least one of a UE identifier for identifying UE100, a node identifier for identifying SN200S with which the cooperative operation is to be performed, a cell identifier for identifying a cell of SN200S with which the cooperative operation is to be performed, a type identifier indicating the type of cooperative operation, and UE context of UE100.

[0095] In step S105, if the SN200S#1 that has received the request message from the MN200M does not have an internode interface with the SN200S#2 specified in the request message, it transmits a message (e.g., an XN SETUP REQUEST message) requesting the establishment of the internode interface to the SN200S#2. If the SN200S#1 has established an internode interface with the SN200S#2 specified in the request message, it does not need to transmit a message (e.g., an XN SETUP REQUEST message) requesting the establishment of the internode interface to the SN200S#2.

[0096] In step S106, when the SN 200S#2 receives the message from the SN 200S#1 in step S105, the SN 200S#2 transmits a response message (for example, an XN SETUP RESPONSE message) to the message to the SN 200S#1. As a result, an inter-node interface is established between the SN 200S#1 and the SN 200S#2.

[0097] In step S107, the SN 200S#1 that has received the request message from the MN 200M transmits a request message (e.g., an S-node Coordination Request message) for starting a specified coordinated operation to the SN 200S#2 that is specified in the request message. The request message includes at least one of the above-mentioned information 1) to 5), similar to the message in step S104.

[0098] In step S108, the SN200S#2 that received the request from the SN200S#1 in step S107 accepts the request, performs various settings, and then transmits a response message (for example, an S-node Coordination Response message) to the SN200S#1. The response message may include RRC settings related to the SN200S#2. The RRC settings include at least one of the following a) and b).

[0099] a) Configuration information for cells (candidate cells) managed by SN200S#2: The setting information may include setting information of the cell, such as a cell ID, a physical layer setting, etc., or may include setting information of a TRP managed by the cell.

[0100] b) L1 Measurement Report Settings.

[0101] In step S109, the SN 200S#1 transmits a response message (for example, an S-node Pairing Response message) to the request message in step S104 to the MN 200M. The response message may include the RRC configuration of the SN 200S#2 (obtained in step S108, which may include the configuration of the L1 Measurement Report) and / or the RRC configuration of the SN 200S#1.

[0102] In step S110, the MN 200M may transmit an RRC Reconfiguration message to the UE 100. Alternatively, the SN 200S#1 may transmit the RRC Reconfiguration message to the UE 100 instead of the MN 200M. The RRC Reconfiguration message may include configuration information regarding the SN 200S#1 (e.g., RRC configuration) and / or configuration information regarding the SN 200S#2 (e.g., RRC configuration and / or L1 Measurement Report configuration). In the first embodiment, the RRC Reconfiguration message may include an LTM candidate cell configuration (LTM Candidate Configuration) in which the cell of the SN 200S#2 is a candidate cell.

[0103] In step S111, the UE 100 may store the setting information in the RRC Reconfiguration message, and transmit an RRC Reconfiguration Complete message to the MN 200M (or the SN 200S#1).

[0104] In step S112, the SN 200S#1 and the SN 200S#2 are set in the UE 100, thereby entering a multi-connectivity state. Here, the SN 200S#1 and the SN 200S#2 control the UE 100 in cooperation with each other.

[0105] In step S113, the UE 100 may transmit an L1 Measurement Report to the SN 200S#1. The SN 200S#1 may determine cell switching to the cell of the SN 200S#2 based on the L1 Measurement Report.

[0106] In step S114, the SN 200S#1 transmits to the UE 100 a Cell Switch Command (MAC CE) including information indicating the cell of the SN 200S#2.

[0107] In step S115, the UE 100 applies the setting of the cell of the SN 200S#2 (target cell) in response to the Cell Switch Command (MAC CE), and detaches from the cell of the SN 200S#1 (source cell).

[0108] In step S116, the UE 100 accesses the cell (target cell) of the SN 200S#2.

[0109] In step S117, when the SN 200S#2 detects the access of the UE 100 (connection completion), the SN 200S#2 may notify the SN 200S#1 of the UE access completion. The notification may include the UE context of the UE 100. The notification may include the latest RRC setting (contents of RRC Reconfiguration).

[0110] In step S118, the SN 200S#1 may notify the MN 200M that the PSCell (PCell) change of the UE 100 has been completed. The notification may include the UE context of the UE 100. The notification may include the latest RRC setting (contents of RRC Reconfiguration). The notification may include information such as the node ID of the SN 200S#2.

[0111] (1.7) Modification of the First Embodiment In the above-described first embodiment, an example in which the MN 200M determines (specifies) the combination of the SNs 200S to operate in cooperation has been described, but the SN 200S may determine the combination of the SNs 200S to operate in cooperation.

[0112] Fig. 12 is a diagram showing a modified example of the operation of the mobile communication system according to the first embodiment. In Fig. 12, non-essential steps are indicated by dashed lines.

[0113] In this modification, in step S120, the SN200S#1 determines a combination of SN200S to operate in cooperation with the SN200S#1. The SN200S#1 may determine the SN200S#2 as the SN200S to operate in cooperation with the SN200S#1 based on the combination of SN200S (or combination of cells) set by the network operator (OAM).

[0114] In step S121, the SN 200S#1 transmits a message (for example, an S-node Pairing Required message) indicating a request for cooperation with the SN 200S#2 to the MN 200M. The message includes at least one of the information items 1) to 5) above.

[0115] Then, in step S104, the MN 200M transmits an S-node Pairing Request message, which is a request message (first message) for cooperative operation, to the SN 200S#1. This message is the same as in the above-mentioned embodiment. Alternatively, in step S104, the MN 200M may transmit to the SN 200S#1 a response message to the effect that the request in step S121 is permitted. Subsequent operations are the same as in the above-mentioned embodiment.

[0116] (2) Second embodiment The second embodiment will be described with reference to Figs. 13 and 14, focusing mainly on the differences from the above-described first embodiment.

[0117] In the above-described first embodiment, an example has been described in which the cooperative operation between a plurality of SNs 200S is a cell switching operation for switching a serving cell of a UE 100 between the SNs 200S. In contrast, in the second embodiment, the cooperative operation between a plurality of SNs 200S is an operation in which a certain SN 200S (first secondary node) performs, on the UE 100, setting and / or control of communication between another SN 200S (second secondary node) and the UE 100 on behalf of the MN 200M. That is, in the second embodiment, the SN 200S functions as a proxy node (also referred to as a "proxy MN") of the MN 200M in order to perform setting and / or control related to the other SNs 200S. This makes it possible to suppress an increase in the load on the MN 200M even when multi-connectivity is performed.

[0118] FIG. 13 is a diagram for explaining an operation scenario of the mobile communication system according to the second embodiment.

[0119] In the illustrated example, the UE 100 performs wireless communication using multi-connectivity with the MN 200M and a plurality of SNs 200S (SN200S#1 to SN200S#3).

[0120] The SN200S#1 has a narrower cell coverage than the MN200M. Specifically, the SN200S#1 operates at a higher frequency than the MN200M. For example, the MN200M may operate in the Sub-6 band, and the SN200S#1 may operate in the mmW band.

[0121] Each of the SN200S#2 and SN200S#3 has a narrower cell coverage than the SN200S#1. Specifically, each of the SN200S#2 and SN200S#3 operates at a higher frequency than the SN200S#1. For example, the SN200S#1 may operate in the mmW band, and each of the SN200S#2 and SN200S#3 may operate in the THz band.

[0122] In such a scenario, the MN 200M causes the SN 200S#1 to control the SN 200S#2 and the SN 200S#3 (i.e., delegates the control authority). The SN 200S#1 to which the control authority has been delegated sets up and / or controls the communication between the UE 100 and the SN 200S#2 and the SN 200S#3 on behalf of the MN 200M for the UE 100.

[0123] Fig. 14 is a diagram showing an example of the operation of the mobile communication system according to the second embodiment. In Fig. 14, non-essential steps are indicated by dashed lines.

[0124] In step S201, the UE 100 performs wireless communication using dual connectivity (DC) with the MN 200M and the SN 200S#1.

[0125] In step S202, the UE 100 may transmit a Measurement Report message including a measurement result of the radio quality of each cell to the MN 200M. The MN 200M may receive the Measurement Report message from the UE 100.

[0126] In step S203, the MN200M determines a combination of SN200S to be operated in cooperation with each other. For example, the MN200M identifies a cell whose wireless quality satisfies a predetermined condition based on the Measurement Report message in step S202, and determines the SN200S to which the identified cell belongs. Here, it is assumed that the MN200M has determined the SN200S#2 as the SN200S to be operated in cooperation with the SN200S#1. The MN200M may determine the SN200S#2 as the SN200S to be operated in cooperation with the SN200S#1 based on the combination of SN200S (or combination of cells) set by the network operator (OAM). In the second embodiment, the MN200M may determine the SN200S#1 as the SN200S (proxy MN) that controls the SN200S#2.

[0127] In step S204, the MN 200M transmits an S-node Pairing Request message, which is a request message (first message) for cooperative operation, to the SN 200S#1. In the illustrated example, the MN 200M transmits the S-node Pairing Request message to the SN 200S#1, but the MN 200M may transmit the S-node Pairing Request message to the SN 200S#2, or may transmit the S-node Pairing Request message to both the SN 200S#1 and the SN 200S#2. In the second embodiment, the S-node Pairing Request message may be an operation request for performing SN control as a proxy MN, specifically, a message indicating designation of the SN 200S#1 as the SN 200S (proxy MN) that performs control regarding the SN 200S#2.

[0128] In the illustrated example, the request message for cooperation (first message) is a new message transmitted and received on an inter-node interface, but the request message for cooperation (first message) may be an existing message (e.g., an S-NODE MODIFICATION REQUEST message) defined in the 3GPP technical specifications. The request message for cooperation (first message) may be a request message (e.g., an S-node Xn Establishment Request message) requesting establishment of an inter-node interface between SN200S.

[0129] The request message for cooperative operation (first message) includes at least one of the above-mentioned information 1) to 5). In the second embodiment, the information indicating the type of cooperative operation to be performed (4) may be information indicating a "proxy MN".

[0130] In step S205, if the SN200S#1 that has received the request message from the MN200M does not have an internode interface with the SN200S#2 specified in the request message, it transmits a message (e.g., an XN SETUP REQUEST message) requesting the establishment of the internode interface to the SN200S#2. If the SN200S#1 has established an internode interface with the SN200S#2 specified in the request message, it does not need to transmit a message (e.g., an XN SETUP REQUEST message) requesting the establishment of the internode interface to the SN200S#2.

[0131] In step S206, when the SN 200S#2 receives the message from the SN 200S#1 in step S205, the SN 200S#2 transmits a response message (for example, an XN SETUP RESPONSE message) to the message to the SN 200S#1. As a result, an inter-node interface is established between the SN 200S#1 and the SN 200S#2.

[0132] In step S207, the SN 200S#1 that has received the request message from the MN 200M transmits a request message (for example, an S-node Coordination Request message) to the SN 200S#2 that is specified in the request message to start the specified coordinated operation. The request message includes at least one of the above information 1) to 5), similar to the message in step S204.

[0133] In step S208, the SN200S#2 that received the request from the SN200S#1 in step S207 accepts the request, performs various settings, and then transmits a response message (e.g., an S-node Coordination Response message) to the SN200S#1. The response message may include RRC settings for the SN200S#2. The RRC settings may include setting information for a cell (candidate cell) managed by the SN200S#2. The setting information may include setting information for the cell, such as a cell ID and physical layer settings.

[0134] In step S209, the SN 200S#1 transmits a response message (for example, an S-node Pairing Response message) to the request message in step S204 to the MN 200M. The response message may include the RRC configuration of the SN 200S#2 (obtained in step S208) and / or the RRC configuration of the SN 200S#1.

[0135] In step S210, the MN 200M may transmit an RRC Reconfiguration message to the UE 100. Alternatively, the SN 200S#1 may transmit the RRC Reconfiguration message to the UE 100 instead of the MN 200M. The RRC Reconfiguration message may include setting information (e.g., RRC settings) regarding the SN 200S#1 and / or setting information (e.g., RRC settings) regarding the SN 200S#2.

[0136] In step S211, the UE 100 may store the setting information in the RRC Reconfiguration message, and transmit an RRC Reconfiguration Complete message to the MN 200M (or the SN 200S#1).

[0137] In step S212, the SN 200S#1 and the SN 200S#2 are set in the UE 100, thereby entering a multi-connectivity state. Here, the SN 200S#1 and the SN 200S#2 control the UE 100 in cooperation with each other.

[0138] In step S213, the SN200S#1 performs dual connectivity (DC) with the SN200S#2. If a DC between the MN200M and the SN200S#1 has been set, the DC setting between the SN200S#1 and the SN200S#2 may be performed in a manner that takes over the DC setting. Alternatively, if there is no DC between the MN200M and the SN200S#1, or if the DC setting between the MN200M and the SN200S#1 has been discarded, the DC setting between the SN200S#1 and the SN200S#2 may be performed as a new setting.

[0139] In steps S214 to S216, the SN 200S#1 operates as a proxy MN and performs control related to the SN 200S#2. For example, the SN 200S#1 may take the initiative in changing the PSCell of the UE 100 from the SN 200S#2 to the SN 200S#3.

[0140] In step S217, when the UE context and / or RRC setting held by the SN200S#1 is updated, the SN200S#1 may transmit the UE context and / or RRC setting to the MN200M. Also, when the MN200M changes the setting of the UE100 and the UE context and / or RRC setting held by the MN200M is changed, the MN200M may transmit the UE context and / or RRC setting to the SN200S#1. This performs synchronization processing so that the MN200M and the SN200S#1 (proxy MN) hold the same UE context and / or RRC setting.

[0141] In addition, in the second embodiment, the SN200S#1 operating as a proxy MN may send a request message to the SN200S to be controlled (e.g., SN200S#2) to request a PSCell change using LTM between SN200S in the first embodiment.

[0142] Also in the second embodiment, the same operation as in the modified example of the first embodiment may be applied.

[0143] (3) Other embodiments The operational flows in the above-described embodiments do not necessarily have to be performed in chronological order according to the order depicted in the flow diagram. For example, steps in the operations may be performed in an order different from that depicted in the flow diagram, or may be performed in parallel. Also, some of the steps in the operations may be deleted, and additional steps may be added to the process.

[0144] A program may be provided that causes a computer (UE 100, node 200) to execute the operations according to the above-described embodiment. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0145] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless otherwise specified. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "depending at least in part on." Additionally, the terms "include," "comprise," and variations thereof do not mean including only the recited items, but may include only the recited items, or may include additional items in addition to the recited items. Additionally, the term "or" as used in this disclosure is not intended to mean an exclusive or. Additionally, any reference to elements using designations such as "first," "second," etc., as used in this disclosure is not intended to generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as, for example, a, an, and the in English, these articles are intended to include the plural unless the context clearly indicates otherwise.

[0146] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes, etc. are possible without departing from the spirit of the invention.

[0147] (4) Additional Notes The following additional features relate to the above-described embodiment.

[0148] (Appendix 1) A communication method for a user equipment to perform wireless communication with a master node and a plurality of secondary nodes in a mobile communication system, comprising: A step of performing a process in which the master node delegates control authority for performing setting and / or control regarding cooperative operation between the plurality of secondary nodes to at least one of the plurality of secondary nodes for the user device; and a step of the secondary node to which the control authority has been delegated performing settings and / or control regarding the cooperative operation for the user device. Communication methods.

[0149] (Appendix 2) The step of performing the delegation process includes a step of transmitting a first message for requesting the cooperative operation from the master node to at least one of the plurality of secondary nodes. 2. A communication method as described in claim 1.

[0150] (Appendix 3) The first message includes at least one of a user equipment identifier for identifying the user equipment, a node identifier for identifying a secondary node that is a partner of the cooperative operation, a cell identifier for identifying a cell of the secondary node that is a partner of the cooperative operation, a type identifier indicating a type of the cooperative operation, and a user equipment context of the user equipment. 2. A communication method as described in claim 1.

[0151] (Appendix 4) a step of a first secondary node receiving the first message transmitting a second message for starting the cooperative operation to a second secondary node; 4. The communication method according to claim 2 or 3.

[0152] (Appendix 5) the plurality of secondary nodes include a first secondary node to which the control authority is delegated and a second secondary node, The cooperative operation includes a cell switching operation of switching a serving cell of the user equipment from a cell of the first secondary node to a cell of the second secondary node. 5. A communication method according to any one of claims 1 to 4.

[0153] (Appendix 6) The step of configuring and / or controlling the cooperative operation includes a step of the first secondary node configuring and / or controlling the cell switching operation for the user equipment using layer 1 and / or layer 2 signaling. 6. A communication method as described in claim 5.

[0154] (Appendix 7) the plurality of secondary nodes include a first secondary node to which the control authority is delegated and a second secondary node, The step of setting and / or controlling the cooperative operation includes a step of the first secondary node setting and / or controlling communication between the user device and the second secondary node on behalf of the master node for the user device. 7. A communication method according to any one of claims 1 to 6.

[0155] (Appendix 8) A node that operates as a master node in a mobile communication system in which a user device performs wireless communication with a master node and a plurality of secondary nodes, a control unit that performs a process of delegating control authority for performing settings and / or control regarding cooperative operations between the plurality of secondary nodes to the user device, to at least one of the plurality of secondary nodes; node.

[0156] (Appendix 9) A node that operates as a secondary node in a mobile communication system in which a user device performs wireless communication with a master node and a plurality of secondary nodes, a control unit that, when a control authority for setting and / or controlling the cooperative operation between the plurality of secondary nodes is delegated from the master node to the user device, performs setting and / or control regarding the cooperative operation between the plurality of secondary nodes to the user device. node.

[0157] (Appendix 10) A user device that performs wireless communication with a master node and a plurality of secondary nodes, a wireless communication unit that receives a signal for setting and / or controlling the cooperative operation between the plurality of secondary nodes from a secondary node to which control authority for performing the setting and / or control on the user device regarding the cooperative operation between the plurality of secondary nodes is delegated from the master node; User equipment. [Explanation of symbols]

[0158] 1 :NW 10:RAN 20 :CN 100:UE 110: Receiving unit 120: Transmitter 130: Control section 140: Wireless communication unit 200: Node 200M :MN 200S :SN 210: Transmission unit 220: Receiving unit 230: Control section 240: Network Communications Department 250: Wireless communication section 300:CN device

Claims

1. A communication method for a user equipment to perform wireless communication with a master node and a plurality of secondary nodes in a mobile communication system, comprising: A step of performing a process in which the master node delegates control authority for performing setting and / or control regarding cooperative operation between the plurality of secondary nodes to the user device to at least one of the plurality of secondary nodes; The secondary node to which the control authority has been delegated performs setting and / or control regarding the cooperative operation for the user device. Communication methods.

2. The step of performing the delegation process includes a step of transmitting a first message for requesting the cooperative operation from the master node to at least one of the plurality of secondary nodes. The communication method according to claim 1 .

3. The first message includes at least one of a user equipment identifier for identifying the user equipment, a node identifier for identifying a secondary node that is a partner of the cooperative operation, a cell identifier for identifying a cell of the secondary node that is a partner of the cooperative operation, a type identifier indicating a type of the cooperative operation, and a user equipment context of the user equipment. The communication method according to claim 2 .

4. a step of a first secondary node receiving the first message transmitting a second message for initiating the cooperative operation to a second secondary node; The communication method according to claim 2 .

5. the plurality of secondary nodes include a first secondary node to which the control authority is delegated and a second secondary node, The cooperative operation includes a cell switching operation of switching a serving cell of the user equipment from a cell of the first secondary node to a cell of the second secondary node. A communication method according to any one of claims 1 to 4.

6. The step of configuring and / or controlling the cooperative operation includes a step of the first secondary node configuring and / or controlling the cell switching operation for the user equipment using layer 1 and / or layer 2 signaling. The communication method according to claim 5.

7. the plurality of secondary nodes include a first secondary node to which the control authority is delegated and a second secondary node, The step of configuring and / or controlling the cooperation includes a step of the first secondary node configuring and / or controlling communication between the user device and the second secondary node on behalf of the master node for the user device. A communication method according to any one of claims 1 to 4.

8. A node that operates as a master node in a mobile communication system in which a user device performs wireless communication with a master node and a plurality of secondary nodes, a control unit that performs processing to transfer control authority for performing settings and / or control regarding cooperative operations between the plurality of secondary nodes to the user device, to at least one of the plurality of secondary nodes; node.

9. A node that operates as a secondary node in a mobile communication system in which a user device performs wireless communication with a master node and a plurality of secondary nodes, a control unit that, when a control authority for setting and / or controlling the cooperative operation between the plurality of secondary nodes is delegated from the master node to the user device, performs setting and / or control regarding the cooperative operation with respect to the user device. node.

10. A user device that performs wireless communication with a master node and a plurality of secondary nodes, a wireless communication unit that receives a signal for setting and / or controlling the cooperative operation between the plurality of secondary nodes from a secondary node to which control authority for performing the setting and / or control on the user device regarding the cooperative operation between the plurality of secondary nodes is delegated from the master node; User equipment.

Images