WO2022234781A1 - Base station and communication control method - Google Patents

Abstract

A base station (200, 201) according to an embodiment of the present disclosure operates as a master node in a dual-connection scheme in which a user equipment (100) can utilize wireless resources provided from a master node managing a master cell group and a secondary node managing a secondary cell group, the base station (200, 201) comprising: a wireless communication unit (212) for transmitting to the user equipment (100) CPAC configuration information for adding or changing a primary cell of the secondary cell group if a condition concerning wireless quality is satisfied; a control unit (214) for acquiring from the user equipment (100) CPAC failure information regarding a failure to add or change the primary cell on the basis of the CPAC configuration information, and generating failure information based on the CPAC failure information; and a network communication unit (213) for transmitting the failure information to one or a plurality of other base stations (200, 202, 203).

Description

Base station and communication control method Cross-references to related applications

This application is based on and claims the benefit of priority from patent application number 2021-079076, filed May 7, 2021, the entire contents of which are incorporated by reference. incorporated herein by.

The present disclosure relates to base stations and communication control methods used in mobile communication systems.

In the fifth generation (5G) mobile communication system (5G system), the user equipment can use the radio resources provided by the master node that manages the master cell group and the secondary node that manages the secondary cell group. In (so-called Dual Connectivity), when the conditions related to radio quality are satisfied in the user equipment, the user equipment changes the primary cell of the secondary cell group in the secondary node without the involvement of the master node (so-called intra -SN CPC (Conditional PS Cell Change)) is defined (see, for example, Non-Patent Document 1).

In recent years, 3GPP (registered trademark; the same shall apply hereinafter), which is a standardization project for mobile communication systems, has already provided radio resources to user equipments in a dual access scheme when the user equipments have satisfied the conditions regarding radio quality. The introduction of an operation (so-called inter-SN CPC) to change from the primary cell of one secondary node to the primary cell of another secondary node (so-called inter-SN CPC) is being considered in the 5G system (see, for example, Non-Patent Document 2). In addition, when the conditions related to radio quality are satisfied in the user equipment, the operation of adding the primary cell of the secondary cell group (so-called CPA (Conditional PS Cell Addition)) is being considered to be introduced in the 5G system (for example, , Non-Patent Document 3).

A base station according to an aspect of the present disclosure, as the master node in a dual access scheme in which user equipment can use radio resources provided from a master node that manages a master cell group and a secondary node that manages a secondary cell group A working base station. The base station includes a radio communication unit that transmits CPAC setting information for adding or changing a primary cell of the secondary cell group to the user equipment when a condition regarding radio quality is satisfied, and based on the CPAC setting information. A control unit that acquires CPAC failure information about the failure of adding or changing the primary cell from the user equipment, generates failure information based on the CPAC failure information, and transmits the failure information to one or more other base stations. and a network communication unit.

A communication control method according to an aspect of the present disclosure is a dual connection scheme in which a user device can use radio resources provided by a master node that manages a master cell group and a secondary node that manages a secondary cell group. This is a communication control method executed in a base station that operates as a The communication control method includes transmitting CPAC setting information for adding or changing a primary cell of the secondary cell group to the user equipment when a condition regarding radio quality is satisfied; Obtaining from the user equipment CPAC failure information about a failure to add or change a primary cell, generating failure information based on the CPAC failure information, and transmitting the failure information to one or more other base stations. and have

Objects, features, advantages, etc. of the present disclosure will become clearer from the following detailed description with reference to the accompanying drawings.
1 is an explanatory diagram showing an example of a schematic configuration of a system according to an embodiment of the present disclosure; FIG. 1 is a diagram showing a configuration example of a protocol stack of a system according to an embodiment of the present disclosure; FIG. FIG. 2 is a diagram illustrating a configuration example of a UE according to an embodiment of the present disclosure; FIG. FIG. 2 is a diagram illustrating a configuration example of a BS according to an embodiment of the present disclosure; FIG. FIG. 2 is a diagram showing an operation example 1 of the mobile communication system according to the embodiment of the present disclosure; FIG. 4 is a diagram showing an example of information included in a message according to an embodiment of the present disclosure; FIG. FIG. 4 is a diagram showing an operation example 2 of the mobile communication system according to the embodiment of the present disclosure;

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in the present specification and drawings, elements that can be described in the same manner can be omitted from redundant description by assigning the same or similar reference numerals.

In the case where the primary cell of the secondary cell group is added or changed (hereinafter referred to as CPAC) when the conditions related to radio quality are satisfied in such a user equipment, the setting of the primary cell of the secondary cell group to the user equipment is , a base station acting as a secondary node or a candidate secondary node that may act as a secondary node.

Here, the user equipment may fail to add or change the primary cell in CPAC. If a base station operating as a secondary node or a candidate secondary node cannot detect failures in addition or change of primary cells, it may always generate the same configuration, resulting in frequent failures in addition or change of primary cells.

Therefore, one object of the present disclosure is to provide a base station and a communication control method that allow a base station that operates as a secondary node or a candidate secondary node to recognize a failure to add or change a primary cell in a secondary cell group in CPAC. do.

(1) System Configuration (1.1) System Overview An example configuration of a system 1 according to an embodiment of the present disclosure will be described with reference to FIG. The system 1 is, for example, a mobile communication system conforming to Technical Specifications (TS) of 3GPP, which is a standardization project for mobile communication systems. In the following, as the system 1, a mobile communication system based on the 3GPP standard 5th Generation System (5GS), that is, NR (New Radio) will be described as an example. Note that the system 1 is not limited to this example. The system 1 may be a TS-compliant system, either LTE (Long Term Evolution) or another generation system (eg, 6th generation) of the 3GPP standard. The system 1 may be a system conforming to a TS of standards other than the 3GPP standards.

As shown in FIG. 1, the system 1 includes a 5G radio access network (so-called Next Generation Radio Access Network: NG-RAN) 20, a 5G core network (5G Core Network: 5GC) 30, a user device (User Equipment: UE) 100 and

The NG-RAN 20 includes a base station (BS) 200, which is a node of the radio access network. BS200 is a radio|wireless communication apparatus which performs radio|wireless communication with UE100. BS200 manages one or more cells. The BS 200 performs radio communication with the UE 100 that has established a connection with its own cell in the radio resource control (RRC) layer. The base station 200 has a radio resource management (RRM) function, a user data (hereinafter simply referred to as “data”) routing function, a measurement control function for mobility control/scheduling, and the like. A "cell" is used as a term indicating the minimum unit of a wireless communication area. A “cell” is also used as a term indicating a function or resource for radio communication with the UE 100 . One cell belongs to one carrier frequency. FIG. 1 shows an example in which BS 201 manages cell C1 and BS 202 manages cell C2. The UE 100 is located in the overlapping area of cell C1 and cell C2.

The BS 200 communicates with the UE 100 using, for example, the RAN protocol stack. The protocol stack includes, for example, an RRC (Radio Resource Control) layer, an SDAP (Service Data Adaptation Protocol) layer, a PDCP (Packet Data Convergence Protocol) layer, an RLC (Radio Link Control) layer, a MAC (Medium Control) layer and a physical layer ( Physical: PHY) layer. However, in the case of LTE, the SDAP layer does not have to exist.

The BS 200 is, for example, a gNB that provides NR user plane and control plane protocol termination towards the UE 100 and is connected to the 5GC 30 via the NG interface. Note that the BS 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination towards the UE 100, eg in LTE.

The BS 200 may include multiple units. The plurality of units may include a first unit hosting a higher layer included in the protocol stack and a second unit hosting a lower layer included in the protocol stack. The upper layers may include the RRC layer, the SDAP layer and the PDCP layer, and the lower layers may include the RLC layer, the MAC layer and the PHY layer. The first unit may be a CU (central unit), and the second unit may be a DU (Distributed Unit). The plurality of units may include a third unit that performs processing below the PHY layer. The second unit may perform processing above the PHY layer. The third unit may be an RU (Radio Unit). The BS 200 may be one of multiple units and may be connected to other units of the multiple units. Also, the BS 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node.

The 5GC 30 includes a core network device 300. The core network device 300 may be a device that supports the control plane, and may be a device that performs various types of mobility management for the UE 100 . The core network device 300 communicates with the UE 100 using NAS (Non-Access Stratum) signaling, and manages information on the tracking area in which the UE 100 resides. Core network device 300 performs paging through base station 200 in order to notify UE 100 of an incoming call. The core network device 300 may be a 5G/NR AMF (Access and Mobility Management Function) or a 4G/LTE MME (Mobility Management Entity).

The core network device 300 is a device that supports the user plane, and is a device that performs data transfer control for the UE 100 . The core network device 300 may be a 5G/NR UPF (User Plane Function) or a 4G/LTE S-GW (Serving Gateway).

The core network device 300 may include AMF and/or UPF, for example. Core network device 300 is connected to BS 200 via an NG interface.

　UE 100 can communicate with BS 200 when located within the coverage area of BS 200. UE 100 can communicate with BS 200 using the protocol stacks described above.

The UE 100 is an example of a communication device. The UE 100 may be a mobile wireless communication device. The UE 100 may be any device that is used by a user. The UE 100 is, for example, a portable wireless communication device such as a mobile phone terminal such as a smart phone, a tablet terminal, a notebook PC, a communication module, or a communication card. Also, the UE 100 may be a vehicle (eg, car, train, etc.) or a device provided in the vehicle (eg, Vehicle UE). The UE 100 may be a transport body other than a vehicle (eg, a ship, an airplane, an aircraft, etc.) or a device (eg, an Aerial UE) provided in a transport body other than a vehicle (eg, a device provided in an aircraft). Also, the UE 100 may be a sensor or a device provided in the sensor. Note that the UE 100 includes a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, and a remote terminal. , remote device, or remote unit.

(1.2) Configuration Example of Protocol Stack A configuration example of the protocol stack of the system 1 will be described with reference to FIG. As shown in FIG. 2, the protocol of the radio section between the UE 100 and the base station 200 includes a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer and RRC (Radio Resource Control) layer.

The PHY layer performs encoding/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 base station 200 via physical channels.

The MAC layer performs data priority control, retransmission processing by hybrid ARQ (HARQ: Automatic Repeat reQuest), random access procedures, and the like. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the base station 200 via transport channels. The MAC layer of base station 200 includes a scheduler. The scheduler determines uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and allocation resources to the UE 100 .

The RLC layer uses the functions of the MAC layer and PHY layer to transmit data to the RLC layer on the receiving side. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

The PDCP layer performs header compression/decompression and encryption/decryption.

An SDAP (Service Data Adaptation Protocol) layer may be provided as an upper layer of the PDCP layer. The SDAP (Service Data Adaptation Protocol) layer performs mapping between an IP flow, which is the unit of QoS control performed by the core network, and a radio bearer, which is the unit of QoS control performed by the AS (Access Stratum).

The RRC layer controls logical channels, transport channels and physical channels according to radio bearer establishment, re-establishment and release. RRC signaling for various settings is transmitted between the RRC layer of UE 100 and the RRC layer of base station 200 . If there is an RRC connection between the RRC of UE 100 and the RRC of base station 200 (that is, the RRC connection is established), UE 100 is in the RRC connected state. When there is no RRC connection between the RRC of UE 100 and the RRC of base station 200 (ie, no RRC connection is established), UE 100 is in RRC idle state. When the RRC connection between the RRC of UE 100 and the RRC of base station 200 is suspended, UE 100 is in RRC inactive state.

The NAS layer located above the RRC layer performs session management and mobility management for UE100. NAS signaling is transmitted between the NAS layer of UE 100 and the NAS layer of core network device 300 .

Note that the UE 100 has an application layer and the like in addition to the radio interface protocol.

(1.3) Dual Connection Method In the dual connection method (so-called Dual Connectivity), the UE 100 in the RRC connected state uses radio resources provided by the base stations 200 located in two different BSs 200. Configured. These base stations 200 are connected via non-ideal backhauls and have different schedulers for allocating the radio resources to the UE 100 . One base station 200 operates as a master node that manages a master cell group (hereinafter MCG), and the other base station 200 operates as a secondary node that manages a secondary cell group (hereinafter SCG). Therefore, the UE 100 can use radio resources provided by the master node and secondary nodes.

A master node is a radio access node that provides control plane connectivity to the core network 30 . A master node may be referred to as a master eNB, a master ng-eNB, or a master gNB. Secondary nodes have no control plane connection to the core network 30 and provide additional radio resources to the UE 100 . A secondary node may be referred to as an en-gNB, a secondary ng-eNB, or a secondary gNB. Here, the master node and/or secondary node are logical entities. In this embodiment, the base station 200 may correspond to a master node and/or a secondary node. That is, the base station 200 may be replaced with a master node and/or a secondary node.

An MCG is a group of serving cells associated with a master node. The MCG consists of a primary cell (referred to as Sp-Cell or P-Cell) and optionally one or more secondary cells (referred to as S-Cells). A SCG is a group of serving cells associated with a secondary node. The SCG consists of a primary cell (referred to as Sp-Cell or PS-Cell) and optionally one or more secondary cells (referred to as S-Cells). Therefore, the Sp cell is the primary cell of the MCG or SCG. UE 100 is configured with one MAC entity for MCG and one MAC entity for SCG.

In the dual connection method, a conditional SCG primary cell (or PS cell) change is performed. In the conditional SCG primary cell change, when the radio quality condition is satisfied in the UE 100, the UE 100 changes the SCG primary cell in the secondary node without the involvement of the master node (so-called intra-SN CPC (Conditional PS Cell Change)) is performed. Further, in the conditional primary cell change, when the radio quality condition is satisfied in the UE 100, from the primary cell of the SCG of the secondary node that has already provided the radio resource to the UE 100 to the primary cell of the SCG of another secondary node A changing operation (so-called inter-SN CPC) may be performed.

Also, in the dual connection method, a conditional SCG primary cell (or PS cell) is added. In the conditional SCG primary cell addition, an operation of adding an SCG primary cell (so-called CPA (Conditional PS Cell Addition)) may be performed when a condition related to radio quality is satisfied in the UE 100.

Such a conditional SCG primary cell addition or change operation may be referred to as CPAC (Conditional PS Cell Addition/Change).

(1.4) Configuration of UE A configuration example of the UE 100 will be described with reference to FIG. As shown in FIG. 3, the UE 100 has an antenna 101, a communication section 120, and a control section .

Under the control of the control unit 130, the communication unit 120 communicates with other communication devices by transmitting and receiving signals via the antenna 101. The communication unit 120, for example, receives radio signals from the BS200 and transmits radio signals to the BS200. Also, the communication unit 120 may, for example, receive radio signals from other UEs and transmit radio signals to other UEs. Note that the antenna 101 may be provided outside the UE 100 .

The communication unit 120 has a receiving unit 121 and a transmitting unit 122. Receiving section 121 converts a radio signal received by antenna 101 into a received signal that is a baseband signal, performs signal processing on the received signal, and outputs the received signal to control section 130 . Transmitter 122 performs signal processing on a transmission signal, which is a baseband signal output from controller 130 , converts the signal into a radio signal, and transmits the radio signal from antenna 101 .

Note that the receiving unit 121 may include one or more receivers. Transmitter 122 may include one or more transmitters. The receiver and transmitter may be configured by one transceiver. Also, the antenna 101 may be used for both reception and transmission.

The control unit 130 performs various controls in the UE 100. The control unit 130 controls communication with the BS 200 or another UE 100 via the communication unit 120, for example. The operation of the UE 100, which will be described later, may be an operation under the control of the control unit 130.

The control unit 130 may include one or more processors capable of executing programs and a memory that stores the programs. One or more processors may execute programs to perform the operations of controller 130 . The program may be a program for causing a processor to execute the operation of control unit 130 .

The processor performs digital processing of signals transmitted and received via the antenna 101 and the RF circuit. The digital processing includes processing of the protocol stack of the RAN. A processor may be a single processor. A processor may include multiple processors. The multiple processors may include a baseband processor for digital processing and one or more processors for other processing. The memory stores programs executed by the processor, parameters for the programs, and data for the programs. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be included within the processor.

In addition, hereinafter, the operation of the functional units (specifically, the communication unit 120 and the control unit 130) included in the UE 100 may be described as the operation of the UE 100.

(1.4) Configuration of BS A configuration example of the BS 200 will be described with reference to FIG. As shown in FIG. 4 , BS 200 has antenna 211 , radio communication section 212 , network communication section 213 and control section 214 .

Under the control of the control unit 214, the wireless communication unit 212 communicates with the UE 100 via the antenna 211. The wireless communication unit 212 has a receiving unit 212a and a transmitting unit 212b. The receiving unit 212 a converts a radio signal received by the antenna 211 into a received signal that is a baseband signal, performs signal processing on the received signal, and outputs the received signal to the control unit 214 . The transmission unit 212 b performs signal processing on a transmission signal, which is a baseband signal output from the control unit 214 , converts the signal into a radio signal, and transmits the radio signal from the antenna 211 .

The network communication unit 213 is connected to the core network device 300. The network communication unit 213 performs network communication with the core network device 300 under the control of the control unit 214 .

The control unit 214 controls the wireless communication unit 212 and performs various controls in the base station 200 . Control unit 214 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The memory may include at least one of ROM, EPROM, EEPROM, RAM and flash memory. The processor may include a digital signal processor (DSP), which performs digital processing of digital signals, and a central processing unit (CPU), which executes programs. Note that part of the memory may be provided in the wireless communication unit 212 . Also, the DSP may be provided in the wireless communication unit 212 .

In the BS200 configured in this way, the radio communication unit 212 transmits to the UE100 CPAC setting information for adding or changing the primary cell of the SCG when the condition regarding radio quality is satisfied. The control unit 214 acquires CPAC failure information regarding the failure of addition or change of the primary cell based on the CPAC configuration information from the UE 100, and generates failure information based on the CPAC failure information. Network communication unit 213 transmits failure information to one or more other BSs 200 . This allows other BSs 200 to grasp the failure of adding or changing the primary cell of SCG in CPAC based on the failure information. Other BSs 200 may decide to set the primary cell for the SCG, for example, based on perceived failures.

One or more other BSs 200 may include BSs 200 operating as secondary nodes. Thereby, BS200 which operates as a secondary node can grasp failure of addition or change of the primary cell of SCG in CPAC.

The network communication unit 213 may receive from one or a plurality of other BSs 200 information regarding the configuration of candidate primary cells that can become primary cells to be included in the CPAC configuration information. One or more other BSs 200 may include base stations acting as candidate secondary nodes that may become secondary nodes. This allows the BS 200 operating as a candidate secondary node to grasp the failure of adding or changing the primary cell of the SCG in the CPAC.

The control unit 214 may generate individual failure information for each of the plurality of other BSs 200 based on the CPAC failure information. The network communication unit 213 may transmit individual failure information to each of the other BSs 200 . Thereby, each of the plurality of other BSs 200 can grasp the failure of adding or changing the primary cell of SCG in CPAC. Moreover, compared with the case where common failure information of all other BS200 is transmitted to all other BS200, the amount of information transmitted between BS200 can be reduced.

The CPAC configuration information may include identifiers of one or more candidate primary cells that can become primary cells of the SCG. The control unit 214 may generate individual failure information for each candidate primary cell. The network communication unit 213 may transmit individual failure information corresponding to the candidate primary cells managed by the other BSs 200 to each of the one or more other BSs 200 managing the candidate primary cells. This allows other BSs 200 to grasp the failure of addition or change of SCG primary cells in CPAC for each candidate primary cell. Moreover, compared with the case where common failure information of all other BS200 is transmitted to all other BS200, the amount of information transmitted between BS200 can be reduced.

The failure information may include information indicating the cause of the failure to add or change the primary cell. This allows the BS 200 to grasp the cause of the failure in adding or changing the primary cell. The BS 200 can, for example, decide to set the primary cell for the SCG based on the cause of the failure.

The failure information includes identification information of detected cells detected by the UE 100 in cells other than the candidate primary cells, and the results of measurements performed by the UE 100 on the detected cells. This allows other BSs 200 to determine the setting of the primary cell of the SCG, for example, based on the measurement results of the detected cells.

In addition, hereinafter, the operation of the functional units (specifically, the wireless communication unit 212, the network communication unit 213, and the control unit 214) included in the BS 200 may be described as the operation of the BS 200.

(2) System operation (2.1) Operation example 1
Operation example 1 of the UE 100 and the BS 200 (BS 201, BS 202, BS 203) according to the embodiment of the present disclosure will be described with reference to FIGS.

In this operation example, the UE 100 has established an RRC connection with the BS 201. UE 100 is in the RRC connected state. For BS201, BS202 and BS203 are neighboring base stations. BS201 is BS200 which operates as a master node.

Step S101:
The control unit 214 of the BS 201 determines to perform conditional SCG primary cell addition (hereinafter referred to as CPA as appropriate). The control unit 214 of the BS201 may determine the CPA based on the measurement results obtained from the UE100.

Note that the measurement result is the measurement result of the radio quality measured by the UE 100. The wireless communication unit 212 of the BS 201 receives the measurement result from the UE 100, so that the control unit 214 of the BS 201 can acquire the measurement result.

The control unit 214 of the BS 201 determines candidate secondary nodes that may become secondary nodes based on the measurement results. Specifically, control section 214 of BS 201 determines BS 200 that manages a cell with good radio quality as a candidate secondary node. In this operation example, the control unit 214 of the BS201 determines the BS202 as the candidate secondary node. Also, the control unit 214 of the BS 201 may determine the BS 203 as a candidate secondary node. Note that a candidate secondary node may be referred to as a target secondary node.

Step S102:
Network communication unit 213 of BS 201 transmits an SN addition request message to the candidate secondary node. Specifically, network communication section 213 of BS 201 transmits an SN addition request message to BS 202 . Network communication unit 213 of BS 202 receives the SN addition request message. Network communication section 213 of BS 201 may send an SN addition request message to BS 203 . Network communication unit 213 of BS 203 may receive the SN addition request message.

The SN addition request message may be a message requesting to operate as a secondary node in the dual access scheme, or a message requesting addition of the SCG primary cell in the dual access scheme, It may be a message requesting the addition of a conditional SCG primary cell in a dual access scheme. The SN addition request message may contain the measurement result.

Step S103:
Control unit 214 of BS 202 determines whether to approve the request from BS 201 . Controller 214 of BS 202 may decide whether to approve the request based on the measurement results. In this operation example, the control unit 214 of the BS 202 determines to approve the CPA.

The control unit 214 of the BS 202 may generate SCG setting information regarding SCG settings. The SCG setting information is information included in the CPAC setting described later. The SCG configuration information includes information about the configuration of candidate primary cells that can become primary cells (Sp cells or PS cells) of the SCG. The information may include, for example, identifiers of candidate primary cells. Also, the SCG configuration information may include information regarding the configuration of candidate secondary cells that may become secondary cells of the SCG. The information may include, for example, identifiers of candidate secondary cells.

Step S104:
Network communication unit 213 of BS202 transmits an SN addition request approval message to BS201. Network communication unit 213 of BS 201 receives the SN addition request acknowledge message.

The SN addition request approval message is a message that approves the request from the BS201. The controller 214 of the BS 202 may include the SCG configuration information in the SN addition request acknowledge message.

Based on the SN addition request approval message, the control unit 214 of BS201 grasps that BS203 operates as a candidate secondary node for UE100.

The control unit 214 of the BS 201 generates CPAC setting information for adding or changing the primary cell of the SCG when the radio quality condition is satisfied. In this operation example, the CPAC configuration information indicates the configuration for adding the SCG primary cell. The CPAC configuration information may include identifiers of one or more candidate primary cells that may become primary cells for the SCG. If the control unit 214 of the BS 201 has acquired the SCG setting information from the BS 202, it may include the SCG setting information in the CPAC setting information.

The control unit 214 of the BS 201 may generate execution condition information indicating execution conditions for the UE 100 to start CPAC. The execution condition information may indicate a condition (eg, an event) related to radio quality that triggers initiation of CPAC. Radio quality, for example, received power (RSRP: Reference Signal Received Power), received quality (RSRQ: Reference Signal Received Quality), signal-to-interference plus noise power ratio (SINR: Signal-to-Interference plus Noise Power Ratio) at least any or The control unit 214 of the BS 201 may include the execution condition information in the CPAC setting information.

Step S105:
Control section 214 of BS 203 determines whether or not to approve the request from BS 201 in response to receiving the SN addition request message. In this operation example, the control unit 214 of the BS 203 decides not to approve the CPA, that is, to reject it.

Step S106:
Network communication section 213 of BS203 transmits an SN addition request rejection message to BS201. Network communication unit 213 of BS 201 receives the SN addition request rejection message. The SN addition request rejection message is a message rejecting the request from BS201.

Based on the SN addition request rejection message, the control unit 214 of BS201 grasps that BS203 does not operate as a secondary node for UE100.

Step S107:
Radio communication section 212 of BS 201 transmits the RRC reconfiguration message to UE 100 . Communication unit 120 of UE 100 receives the RRC reconfiguration message.

The RRC reset message is a message for resetting radio resource control. The RRC reconfiguration message contains CPAC configuration information. Thereby, radio communication section 212 of BS 201 transmits the CPAC setting information to UE 100 . The communication unit 120 of the UE 100 receives the CPAC setting information. The control unit 130 of the UE 100 applies settings based on the CPAC setting information.

Step S108:
After applying the configuration based on the CPAC configuration information, communication section 120 of UE 100 transmits an RRC reconfiguration complete message to BS 201 . Radio communication section 212 of BS 201 receives the RRC reconfiguration complete message.

Step S109:
The control unit 130 of the UE 100 evaluates execution conditions based on the execution condition information. Specifically, control section 130 of UE 100 measures the radio quality of candidate primary cells. The UE 100 determines whether the radio quality measurement results (eg, received power (RSRP), received quality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) for candidate primary cells satisfy execution conditions.

　UE 100 may execute a random access procedure for establishing an RRC connection with BS 200 that manages the candidate primary cell when the measurement result of the candidate primary cell satisfies the execution conditions.

Step S110:
Control unit 130 of UE 100 determines that CPAC has failed. The control unit 130 of the UE 100 determines that CPAC has failed in any of the following cases.
(a) No candidate primary cell could be detected.
(b) A candidate primary cell could be detected, but the measurement result did not satisfy the execution conditions. There were no candidate cells that met the execution conditions.
(c) The measurement result satisfies the execution condition, but the random access procedure fails.

When the control unit 130 of the UE 100 determines that CPAC has failed, the process of step S111 is executed.

When the measurement result satisfies the execution condition and the random access procedure succeeds, the control unit 130 of the UE 100 executes communication using the dual connection method with the BS 201 as the master node and the BS 202 as the secondary node.

Step S111:
Communication section 120 of UE 100 transmits CPAC failure information to BS 201 . Radio communication section 212 of BS 201 receives the CPAC failure information.

　CPAC failure information is information about a failure to add or change a primary cell based on CPAC setting information. In this operation example, the information is related to the failure to add the primary cell based on the CPAC setting information.

The CPAC failure information may include cause information (eg, cpac-FailureCause) that indicates the cause of the failure of adding or changing the primary cell of the SCG. The cause information may include, for example, information indicating that the candidate primary cell could not be detected (eg, noPSCellDetected). The cause information may also include, for example, information (eg, noEventFulfilled) indicating that there was no candidate primary cell that satisfies the execution condition. In this case, it may include a list of detected candidate primary cell identifiers (eg, physical cell identifiers). The cause information may also include, for example, information indicating that the random access procedure has failed (eg, rach-Failure). In this case, it may include a list of candidate primary cell identities (eg, physical cell identities) that satisfy the execution condition.

The CPAC failure information may include identification information of detected cells other than the candidate primary cell configured in UE 100 and the results of measurements performed on the detected cells by UE 100. CPAC failure information may include, for example, a list (eg, otherDetectedCellList) of identities of detected cells (eg, carrierFreq) and measurement results (eg, measResultCellList). The identity of the detected cell may be, for example, the physical cell identifier of the candidate primary cell or the frequency identifier (eg, absolute radio frequency channel number (ARFCN)) of the detected cell.

The control unit 214 of the BS 201 acquires CPAC failure information from the UE 100. The control unit 214 of the BS 201 generates failure information based on the CPAC failure information. The failure information may include at least part of the information included in the CPAC failure information. The failure information may include cause information, and may include identification information of detected cells and measurement results. The control unit 214 of the BS 201 may generate failure information common to a plurality of BSs 200, for example.

The control unit 214 of the BS201 may generate individual failure information corresponding to each of the plurality of BS200. The control unit 214 of the BS 201, for example, for each BS 200 that manages the cell indicated by the identifier of the candidate primary cell and/or the identification information of the detected cell included in the CPAC failure information, information associated with the identifier or identification information ( For example, individual failure information including cause information, measurement results, etc.) may be generated.

Also, the control unit 214 of the BS 201 may generate individual failure information for each cell. For example, controller 214 of BS 201 may generate individual failure information for each candidate primary cell. The control unit 214 of the BS 201, for example, for each cell indicated by the identifier of the candidate primary cell and/or the identification information of the detected cell included in the CPAC failure information, information associated with the identifier (for example, cause information, measurement result etc.) may be generated.

Also, the control unit 214 of the BS 201 may generate individual failure information for each detected cell. The control unit 214 of the BS 201, for example, for each cell indicated by the identification information of the detected cell included in the CPAC failure information, generates individual failure information including information associated with the identification information (for example, measurement results). You can

Step S112:
Network communication unit 213 of BS201 transmits failure information to BS202. Network communication unit 213 of BS 202 receives the failure information. Network communication section 213 of BS201 may transmit failure information to BS203. Network communication unit 213 of BS 203 may receive the failure information. The network communication unit 213 of the BS 201 may transmit common failure information or individual failure information to each of the plurality of BSs 200 . As shown in FIG. 6, network communication section 213 of BS 201 may transmit failure information using a cell group configuration information (CG-ConfigInfo) message.

When individual failure information is generated for each of a plurality of BSs 200, network communication section 213 of BS 201 transmits individual failure information corresponding to BS 202 to BS 202, and transmits individual failure information corresponding to BS 203 to BS 203. Send. Also, when individual failure information is generated for each cell, network communication section 213 of BS 201 transmits corresponding individual failure information to BS 200 that manages each cell for which individual failure information is generated.

Note that the control unit 214 of the BS 201 selects, for example, (a) the BS 200 that is the transmission source of the information regarding the configuration of the candidate primary cell, (b) the BS 200 that is the transmission source of the SN addition request approval message, and (c) the transmission destination of the failure information. (d) the BS 200 managing the candidate primary cell indicated by the identifier included in the CPAC failure information; (e) the detection indicated by the identifier or identification information included in the CPAC failure information. At least one of the BSs 200 managing the cell may be determined.

The control unit 214 of the BS 202 can grasp the failure based on the CPAC setting based on the failure information. The controller 214 of the BS 202 can consider the failed SCG setup information and generate the SCG setup information upon subsequent CPAC requests. The control unit 214 of the BS 202 may, for example, make it difficult for a candidate primary cell that could not be detected to be set as the next candidate primary cell.

(2.2) Operation example 2
Operation example 2 of the UE 100 and the BS 200 according to the embodiment of the present disclosure will be described with reference to FIG. Differences from the contents described above will be mainly described. In operation example 2, a secondary node-to-secondary node CPC (SN initiated inter-SN CPC) triggered by a secondary node will be described.

In this operation example, the BS201 operates as the master node of the UE100 and the BS202 operates as the secondary node of the UE100 in the dual access scheme. BS 203 acts as a target secondary node (candidate secondary node). UE 100 has established RRC connections with BS 201 and BS 202 . The UE 100 communicates with the BS 201 via the MCG primary cell managed by the BS 201 , and communicates with the BS 202 via the SCG primary cell managed by the BS 202 .

Step S201:
Network communication unit 213 of BS 202 transmits an SN Change Required message to BS 201 . Network communication section 213 of BS 201 receives the SN change request message.

The SN change request message may be a message requesting to change the BS 200 operating as a secondary node in the dual access scheme, or a message requesting to change the primary cell of the SCG in the dual access scheme. Alternatively, it may be a message requesting a conditional SCG primary cell change in a dual access scheme. The SN change request message may contain the measurement results.

The control unit 214 of the BS 202 decides to request a conditional SCG primary cell change (hereinafter referred to as CPC as appropriate). The control unit 214 of the BS 202 may determine the CPC request based on the measurement results obtained from the UE 100 . The control unit 214 of the BS202 may perform control to transmit an SN change request message to the BS201 when the CPC request is determined.

Note that the measurement result is the measurement result of the radio quality measured by the UE 100. The wireless communication unit 212 of the BS 202 receives the measurement result from the UE 100, so that the control unit 214 of the BS 202 can acquire the measurement result.

The control unit 214 of the BS 202 may generate execution condition information indicating execution conditions for the UE 100 to start CPAC (CPC in this operation example). The control unit 214 of the BS 202 may include execution condition information in the SN change request message. The execution condition information is the same information as in the first operation example.

Step S202:
The control unit 214 of the BS 201 determines candidate secondary nodes that may become secondary nodes based on the measurement results. Specifically, control section 214 of BS 201 determines BS 200 that manages a cell with good radio quality as a candidate secondary node. In this operation example, the control unit 214 of the BS201 determines the BS203 as the candidate secondary node (target secondary node).

Step S203:
Network communication unit 213 of BS201 transmits a CPC trigger message to BS203. Network communication unit 213 of BS 203 receives the CPC trigger message.

The CPC trigger message may be a message that triggers CPC in BS203. The CPC trigger message may contain measurement results.

The control unit 214 of the BS 203 may generate SCG setting information related to SCG settings in response to receiving the CPC trigger message. The control unit 214 of the BS 203 may generate SCG setting information as in step S103.

Step S204:
Network communication section 213 of BS 203 transmits a CPC Confirmation message, which is a response to the CPC trigger message, to BS 201 . Network communication unit 213 of BS 201 receives the CPC confirmation message. Controller 214 of BS 203 may include the SCG configuration information in the CPC confirmation message.

Steps S205 to S210:
This corresponds to steps S107 to S112 in Operation Example 1.

In addition, in step S210, the control unit 214 of the BS 201 may determine the transmission destination of the failure information to be the BS 200, which is the transmission source of the execution condition information, in addition to the above (a) to (e). This allows the control unit 214 of the BS 202 to generate execution condition information in consideration of the failed execution condition information when transmitting the SN change request message thereafter. The control unit 214 of the BS 202 may generate execution condition information based on the measurement result included in the failure information.

(Other embodiments)
Although embodiments of the disclosure have been described, the disclosure is not limited to the embodiments. For example, in a CPC between secondary nodes (MN initiated inter-SN CPC) triggered by the master node, the same operation as described above may be performed. Also, in the intra-SN CPC, the same operation as described above may be performed.

Also, in the operation example described above, the UE 100 transmits the CPAC failure information to the master node, but this is not the only option. The UE 100 may send CPAC failure information to the secondary node. The secondary node may keep track of failures based on CPAC configuration based on the CPAC failure information. The secondary node may send CPAC failure information to the master node. A master node may generate failure information based on the CPAC failure information.

In addition, each of the operation examples described above is not limited to being implemented separately and independently, and can be implemented by appropriately combining each operation example. Also, for example, the steps in the processes described herein do not necessarily have to be executed in chronological order according to the order described in the flowcharts or sequence diagrams. For example, steps in a process may be performed in an order different from that depicted in a flowchart or sequence diagram, or in parallel. Also, some of the steps in the process may be deleted and additional steps may be added to the process. Furthermore, each operation flow described above is not limited to being implemented independently, but can be implemented by combining two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

For example, a method may be provided that includes the operation of one or more components of the apparatus described herein, and a program may be provided for causing a computer to perform the operation of the components. Further, a computer-readable non-transitional tangible recording medium recording the program may be provided. Such methods, programs, and computer-readable non-transitory tangible computer-readable storage mediums are also included in the present disclosure. Also, at least part of the UE 100 or at least part of the BS 200 may be a chipset or SoC (System on Chip) in which circuits for executing each process performed by the UE 100 or the BS 200 are integrated.

In this disclosure, "transmit" may mean performing processing of at least one layer in the protocol stack used for transmission, or physically transmitting a signal wirelessly or by wire. may mean to Alternatively, "transmitting" may mean a combination of performing the at least one layer of processing and physically transmitting the signal wirelessly or by wire. Similarly, "receive" may mean performing processing of at least one layer in the protocol stack used for reception, or physically receiving a signal wirelessly or by wire. may mean that Alternatively, "receiving" may mean a combination of performing the at least one layer of processing and physically receiving the signal wirelessly or by wire.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to those examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations, including single elements, more, or less, are within the scope and spirit of this disclosure.

Claims (8)

1. Base stations (200, 201) operating as master nodes in a dual access scheme in which a user equipment (100) can use radio resources provided by a master node that manages a master cell group and a secondary node that manages a secondary cell group. ) and
   a radio communication unit (212) that transmits CPAC setting information for adding or changing a primary cell of the secondary cell group to the user equipment (100) when a condition regarding radio quality is satisfied;
   A control unit (214) that acquires CPAC failure information related to the failure of adding or changing the primary cell based on the CPAC configuration information from the user equipment (100) and generates failure information based on the CPAC failure information;
   a network communication unit (213) for transmitting said failure information to one or more other base stations (200, 202, 203).
2. Base station according to claim 1, wherein said one or more other base stations (200, 202, 203) comprise a base station (200, 202) acting as said secondary node.
3. The network communication unit (213) receives from the one or more other base stations (200, 202, 203) information on configuration of candidate primary cells that can be the primary cell to be included in the CPAC configuration information,
   3. The method of claim 1 or 2, wherein said one or more other base stations (200, 202, 203) comprise base stations (200, 202, 203) acting as candidate secondary nodes to potentially become said secondary nodes. Listed base station.
4. The control unit (214) generates individual failure information for each of the plurality of other base stations (200, 202, 203) based on the CPAC failure information,
   The base station according to any one of claims 1 to 3, wherein said network communication unit (213) transmits said individual failure information to each of said plurality of other base stations (200, 202, 203). .
5. The CPAC configuration information includes identifiers of one or more candidate primary cells that can be the primary cells of the secondary cell group;
   The control unit (214) generates individual failure information for each of the candidate primary cells,
   The network communication unit (213) provides each of the one or more other base stations (200, 202, 203) managing the candidate primary cells with 5. The base station according to any one of claims 1 to 4, which transmits the individual failure information corresponding to the candidate primary cells that
6. The base station according to any one of claims 1 to 5, wherein the failure information includes information indicating a cause of failure in addition or change of the primary cell.
7. The failure information includes identification information of a detected cell detected by the user equipment (100) in a cell other than the candidate primary cell that can be the primary cell of the secondary cell group, and identification information of the detected cell detected by the user equipment (100) in the detected cell. 7. A base station according to any one of claims 1 to 6, comprising the results of measurements performed on the base station.
8. Base stations (200, 201) operating as master nodes in a dual access scheme in which a user equipment (100) can use radio resources provided by a master node that manages a master cell group and a secondary node that manages a secondary cell group. ) is a communication control method executed in
   a step of transmitting CPAC setting information for adding or changing a primary cell of the secondary cell group to the user equipment (100) when a condition regarding radio quality is satisfied;
   obtaining from the user equipment (100) CPAC failure information related to the failure of adding or changing the primary cell based on the CPAC configuration information, and generating failure information based on the CPAC failure information;
   and transmitting the failure information to one or more other base stations (200, 202, 203).
   

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