WO2024096097A1 - Terminal device, method, and integrated circuit - Google Patents

Abstract

On the basis of a MAC processing unit of this terminal device having received, from a base station device, a first MAC CE indicating an identifier for identifying one or more candidate target configurations including a target SCell, an RRC processing unit of the terminal device applies, to the RRC configuration of the terminal device, the candidate target configuration identified by the first MAC CE. The MAC processing unit determines whether or not the applied candidate target configuration includes information indicating that the target SCell is to be activated, and activates or de-activates the target SCell on the basis of the determination.

Description

Terminal device, method, and integrated circuit

The present invention relates to a terminal device, a method, and an integrated circuit.
This application claims priority to Japanese Patent Application No. 2022-176092, filed in Japan on November 2, 2022, the contents of which are incorporated herein by reference.

The 3rd Generation Partnership Project (3GPP (registered trademark)), a standardization project for cellular mobile communication systems, is conducting technical studies and formulating standards for cellular mobile communication systems, including wireless access, core networks, and services.

For example, 3GPP has begun technical discussions and standardization of E-UTRA (Evolved Universal Terrestrial Radio Access) as a radio access technology (Radio Access Technology: RAT) for 3.9G and 4G cellular mobile communication systems. 3GPP is currently conducting technical discussions and standardization of E-UTRA extension technologies. E-UTRA is also known as Long Term Evolution (LTE: registered trademark), and the extension technology is sometimes referred to as LTE-Advanced (LTE-A) and LTE-Advanced Pro (LTE-A Pro).

In addition, 3GPP has begun technical studies and standardization of NR (New Radio, or NR Radio access) as a radio access technology (Radio Access Technology: RAT) for cellular mobile communication systems for the 5th generation (5G). 3GPP is currently conducting technical studies and standardization of NR extension technologies.

As an extension technology of NR, there is a serving cell change technology that allows a terminal device to move from the coverage area of one cell to the coverage area of another cell. This serving cell change is triggered by layer 3 (also called RRC) measurements, and synchronized reconfiguration for the serving cell change is triggered by RRC signaling. Compared to RRC signaling, layer 1 or layer 2 signaling has the advantage of low latency and low overhead. For this reason, studies have begun on a serving cell change technology triggered by layer 1 or layer 2 signaling (Layer 1/Layer 2 mobility optimization (L1/L2 mobility enhancement) technology).

The details of the terminal device procedures in Layer 1/Layer 2 mobility optimization technology are one of the issues discussed above. However, it remains unclear how the specifications of the terminal device procedures described in Non-Patent Document 7 and Non-Patent Document 8 are reflected in Layer 1/Layer 2 mobility optimization technology.

One aspect of the present invention was made in consideration of the above circumstances, and one of its objectives is to provide a terminal device, a base station device, a communication method, and an integrated circuit that can efficiently control communications.

In order to achieve the above object, one aspect of the present invention takes the following measures. That is, one aspect of the present invention is a terminal device that communicates with a base station device, and includes a receiver that receives from the base station device a first MAC CE indicating an identifier that identifies one or more candidate target configurations including a target SCell, an RRC processor, and a MAC processor, and based on the MAC processor's reception of the first MAC CE, the RRC processor applies the candidate target configuration identified by the first MAC CE to the RRC configuration of the terminal device, and the MAC processor determines whether the applied candidate target configuration includes information indicating that the target SCell is to be activated, and activates or deactivates the target SCell based on the determination.

Another aspect of the present invention is a method for a terminal device to communicate with a base station device, comprising the steps of: a MAC entity of the terminal device receiving from the base station device a first MAC CE indicating an identifier identifying one or more candidate target configurations including a target SCell; an RRC entity of the terminal device applying the candidate target configuration identified by the first MAC CE to an RRC configuration of the terminal device based on the MAC entity receiving the first MAC CE; a MAC entity determining whether the applied candidate target configuration includes information indicating that the target SCell is to be activated; and activating or deactivating the target SCell based on the determination.

Another aspect of the present invention is an integrated circuit implemented in a terminal device that communicates with a base station device, the integrated circuit having the following functions: a MAC entity of the terminal device receives from the base station device a first MAC CE indicating an identifier that identifies one or more candidate target configurations including a target SCell; an RRC entity of the terminal device applies the candidate target configuration identified by the first MAC CE to the RRC configuration of the terminal device based on the MAC entity receiving the first MAC CE; the MAC entity determines whether the applied candidate target configuration includes information indicating that the target SCell is to be activated; and activates or deactivates the target SCell based on the determination.

These comprehensive or specific aspects may be realized as a system, device, method, integrated circuit, computer program, or recording medium, or as any combination of a system, device, method, integrated circuit, computer program, and recording medium.

According to one aspect of the present invention, a terminal device, method, and integrated circuit can realize efficient communication control processing.

1 is a schematic diagram of a communication system according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of an E-UTRA protocol configuration according to the present embodiment. FIG. 1 is a diagram showing an example of an NR protocol configuration according to the present embodiment. FIG. 2 is a diagram showing an example of a procedure flow for various settings in the RRC according to the present embodiment. FIG. 2 is a block diagram showing the configuration of a terminal device according to the embodiment. FIG. 2 is a block diagram showing the configuration of a base station device according to the present embodiment. An example of an ASN.1 description included in a message regarding reconfiguration of an RRC connection in NR in this embodiment. 13 is an example of an ASN.1 description representing a field and/or an information element related to a ServingCellConfigCommon information element in this embodiment. 5 is an example of processing of a terminal device in the present embodiment.

This embodiment will be described in detail below with reference to the drawings.

LTE (and LTE-A, LTE-A Pro) and NR may be defined as different radio access technologies (Radio Access Technologies: RATs). NR may be defined as a technology included in LTE. LTE may be defined as a technology included in NR. LTE that can be connected to NR via Multi-Radio Dual Connectivity (MR-DC) may be distinguished from conventional LTE. LTE that uses 5GC in the core network (Core Network: CN) may be distinguished from conventional LTE that uses EPC in the core network. Conventional LTE may refer to LTE that does not implement technologies standardized after Release 15 in 3GPP. This embodiment may be applied to NR, LTE, and other RATs. In the following description, terms related to LTE and NR are used, but this embodiment may be applied to other technologies that use other terms. In this embodiment, the term E-UTRA may be replaced with the term LTE, and the term LTE may be replaced with the term E-UTRA.

In this embodiment, the names of each node and entity and the processing in each node and entity when the radio access technology is E-UTRA or NR are described, but this embodiment may be used for other radio access technologies. The names of each node and entity in this embodiment may be different names.

FIG. 1 is a schematic diagram of a communication system according to this embodiment. Note that the functions of each node, radio access technology, core network, interface, etc. described using FIG. 1 are only some of the functions closely related to this embodiment, and the system may have other functions.

E-UTRA 100 may be a radio access technology. E-UTRA 100 may also be an air interface between UE 122 and eNB 102. The air interface between UE 122 and eNB 102 may be referred to as a Uu interface. eNB (E-UTRAN Node B) 102 may be a base station device. eNB 102 may have an E-UTRA protocol, which will be described later. The E-UTRA protocol may be composed of an E-UTRA User Plane (UP) protocol, which will be described later, and an E-UTRA Control Plane (CP) protocol, which will be described later. eNB 102 may terminate the E-UTRA User Plane (UP) protocol and the E-UTRA Control Plane (CP) protocol for UE 122. A radio access network composed of eNBs may be referred to as E-UTRAN.

EPC (Evolved Packet Core) 104 may be a core network. Interface 112 is an interface between eNB 102 and EPC 104, and may be referred to as an S1 interface. Interface 112 may include a control plane interface through which control signals pass, and/or a user plane interface through which user data passes. The control plane interface of interface 112 may terminate at a Mobility Management Entity (MME: not shown) in EPC 104. The user plane interface of interface 112 may terminate at a Serving Gateway (S-GW: not shown) in EPC 104. The control plane interface of interface 112 may be referred to as an S1-MME interface. The user plane interface of interface 112 may be referred to as an S1-U interface.

Note that one or more eNBs 102 may be connected to the EPC 104 via an interface 112. An interface may exist between the multiple eNBs 102 connected to the EPC 104 (not shown). The interface between the multiple eNBs 102 connected to the EPC 104 may be referred to as an X2 interface.

NR106 may be a radio access technology. NR106 may also be an air interface between UE122 and gNB108. The air interface between UE122 and gNB108 may be referred to as a Uu interface. gNB (g Node B) 108 may be a base station device. gNB108 may have the NR protocol described below. The NR protocol may be composed of the NR user plane (User Plane: UP) protocol described below and the NR control plane (Control Plane: CP) protocol described below. gNB108 may terminate the NR user plane (User Plane: UP) protocol and the NR control plane (Control Plane: CP) protocol for UE122.

5GC110 may be a core network. Interface 116 is an interface between gNB108 and 5GC110, and may be referred to as an NG interface. Interface 116 may have a control plane interface through which control signals pass, and/or a user plane interface through which user data passes. The control plane interface of interface 116 may terminate at an Access and Mobility Management Function (AMF: not shown) in 5GC110. The user plane interface of interface 116 may terminate at a User Plane Function (UPF: not shown) in 5GC110. The control plane interface of interface 116 may be referred to as an NG-C interface. The user plane interface of interface 116 may be referred to as an NG-U interface.

Note that one or more gNB108 may be connected to 5GC110 via interface 116. An interface may exist between multiple gNB108 connected to 5GC110 (not shown). The interface between multiple gNB108 connected to 5GC110 may be referred to as an Xn interface.

　eNB102 may have a function to connect to 5GC110. eNB102 with a function to connect to 5GC110 may be called ng-eNB. Interface 114 is an interface between eNB102 and 5GC110, and may be called an NG interface. Interface 114 may have a control plane interface through which control signals pass, and/or a user plane interface through which user data passes. The control plane interface of interface 114 may terminate at the AMF in 5GC110. The user plane interface of interface 114 may terminate at the UPF in 5GC110. The control plane interface of interface 114 may be called an NG-C interface. The user plane interface of interface 114 may be called an NG-U interface. A radio access network composed of ng-eNB or gNB may be called NG-RAN. NG-RAN, E-UTRAN, etc. may simply be called a network. In addition, the network may include eNB, ng-eNB, gNB, etc.

Note that one or more eNB102 may be connected to 5GC110 via interface 114. An interface may exist between multiple eNB102 connected to 5GC110 (not shown). The interface between multiple eNB102 connected to 5GC110 may be called an Xn interface. Furthermore, an eNB102 connected to 5GC110 and a gNB108 connected to 5GC110 may be connected by interface 120. The interface 120 between an eNB102 connected to 5GC110 and a gNB108 connected to 5GC110 may be called an Xn interface.

The gNB108 may have the function of connecting to the EPC104. The gNB108 with the function of connecting to the EPC104 may be called an en-gNB. The interface 118 is an interface between the gNB108 and the EPC104, and may be called an S1 interface. The interface 118 may have a user plane interface through which user data passes. The user plane interface of the interface 118 may terminate at an S-GW (not shown) in the EPC104. The user plane interface of the interface 118 may be called an S1-U interface. In addition, the eNB102 connecting to the EPC104 and the gNB108 connecting to the EPC104 may be connected by an interface 120. The interface 120 between the eNB102 connecting to the EPC104 and the gNB108 connecting to the EPC104 may be called an X2 interface.

Interface 124 is an interface between EPC 104 and 5GC 110, and may be an interface that passes only CP, only UP, or both CP and UP. In addition, some or all of interfaces such as interface 114, interface 116, interface 118, interface 120, and interface 124 may not exist depending on the communication system provided by the communication carrier, etc.

UE122 may be a terminal device capable of receiving system information and paging messages transmitted from eNB102 and/or gNB108. UE122 may also be a terminal device capable of wireless connection with eNB102 and/or gNB108. UE122 may also be a terminal device capable of wireless connection with eNB102 and wireless connection with gNB108 simultaneously. UE122 may have the E-UTRA protocol and/or the NR protocol. The wireless connection may be a Radio Resource Control (RRC) connection.

UE122 may also be a terminal device capable of connecting to EPC104 and/or 5GC110 via eNB102 and/or gNB108. When the core network to which eNB102 and/or gNB108, with which UE122 communicates, is connected is EPC104, each Data Radio Bearer (DRB: Data Radio Bearer) described below established between UE122 and eNB102 and/or gNB108 may further be uniquely linked to each EPS (Evolved Packet System) bearer passing through EPC104. Each EPS bearer may be identified by an EPS bearer identifier (Identity, or ID). Furthermore, the same QoS may be guaranteed for data such as IP packets and Ethernet (registered trademark) frames passing through the same EPS bearer.

Furthermore, if the core network to which eNB102 and/or gNB108, with which UE122 communicates, is connected is 5GC110, each DRB established between UE122 and eNB102 and/or gNB108 may be further linked to one of the PDU (Packet Data Unit) sessions established within 5GC110. One or more QoS flows may exist in each PDU session. Each DRB may be mapped to one or more QoS flows, or may not be mapped to any QoS flow. Each PDU session may be identified by a PDU session identifier (Identity, or ID). Furthermore, each QoS flow may be identified by a QoS flow identifier (Identity, or ID). Furthermore, the same QoS may be guaranteed to data such as IP packets and Ethernet frames passing through the same QoS flow.

　PDU sessions and/or QoS flows may not exist in EPC104. Also, EPS bearers may not exist in 5GC110. When UE122 is connected to EPC104, UE122 has information on EPS bearers, but does not have information on PDU sessions and/or QoS flows. Also, when UE122 is connected to 5GC110, UE122 has information on PDU sessions and/or QoS flows, but does not have information on EPS bearers.

In the following description, eNB102 and/or gNB108 will also be referred to simply as base station devices, and UE122 will also be referred to simply as terminal device or UE.

FIG. 2 is a diagram showing an example of an E-UTRA protocol architecture according to this embodiment. FIG. 3 is a diagram showing an example of an NR protocol architecture according to this embodiment. Note that the functions of each protocol described using FIG. 2 and/or FIG. 3 are only some of the functions closely related to this embodiment, and other functions may also be included. Note that in this embodiment, the uplink (UL) may be a link from a terminal device to a base station device. Also, in this embodiment, the downlink (DL) may be a link from a base station device to a terminal device.

Figure 2(A) is a diagram of the E-UTRA user plane (UP) protocol stack. As shown in Figure 2(A), the E-UTRA UP protocol may be a protocol between the UE 122 and the eNB 102. That is, the E-UTRA UP protocol may be a protocol that terminates at the eNB 102 on the network side. As shown in Figure 2(A), the E-UTRA user plane protocol stack may be composed of PHY (Physical layer) 200, which is the radio physical layer, MAC (Medium Access Control) 202, which is the medium access control layer, RLC (Radio Link Control) 204, which is the radio link control layer, and PDCP (Packet Data Convergence Protocol) 206, which is the packet data convergence protocol layer.

Figure 3(A) is a diagram of the NR user plane (UP) protocol stack. As shown in Figure 3(A), the NRUP protocol may be a protocol between the UE 122 and the gNB 108. That is, the NR UP protocol may be a protocol that terminates at the gNB 108 on the network side. As shown in Figure 3(A), the NR user plane protocol stack may be composed of PHY 300, which is a radio physical layer, MAC 302, which is a medium access control layer, RLC 304, which is a radio link control layer, PDCP 306, which is a packet data convergence protocol layer, and SDAP (Service Data Adaptation Protocol) 310, which is a service data adaptation protocol layer.

Figure 2(B) is a diagram of the E-UTRA control plane (CP) protocol configuration. As shown in Figure 2(B), in the E-UTRA CP protocol, RRC (Radio Resource Control) 208, which is the radio resource control layer, may be a protocol between UE 122 and eNB 102. In other words, RRC 208 may be a protocol that terminates at eNB 102 on the network side. Also, in the E-UTRA CP protocol, NAS (Non Access Stratum) 210, which is the non-AS (Access Stratum) layer, may be a protocol between UE 122 and MME. In other words, NAS 210 may be a protocol that terminates at MME on the network side.

Figure 3(B) is a diagram of the NR control plane (CP) protocol configuration. As shown in Figure 3(B), in the NR CP protocol, RRC308, which is a radio resource control layer, may be a protocol between UE122 and gNB108. In other words, RRC308 may be a protocol that terminates at gNB108 on the network side. Also, in the NR CP protocol, NAS312, which is a non-AS layer, may be a protocol between UE122 and AMF. In other words, NAS312 may be a protocol that terminates at AMF on the network side.

The AS (Access Stratum) layer may be a layer that terminates between the UE 122 and the eNB 102 and/or the gNB 108. In other words, the AS layer may be a layer that includes some or all of the PHY 200, the MAC 202, the RLC 204, the PDCP 206, and the RRC 208, and/or a layer that includes some or all of the PHY 300, the MAC 302, the RLC 304, the PDCP 306, the SDAP 310, and the RRC 308.

In this embodiment, the terms PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) may be used without distinguishing between the E-UTRA protocol and the NR protocol. In this case, PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) may respectively refer to the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) of the E-UTRA protocol, or the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) of the NR protocol. The SDAP (SDAP layer) may also be the SDAP (SDAP layer) of the NR protocol.

In addition, in this embodiment, when distinguishing between E-UTRA protocols and NR protocols, PHY200, MAC202, RLC204, PDCP206, and RRC208 may be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. PHY200, MAC202, RLC204, PDCP206, and RRC208 may be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. Additionally, when distinguishing between E-UTRA protocols and NR protocols, PHY300, MAC302, RLC304, PDCP306, and RRC308 may be referred to as NR PHY, NR MAC, NR RLC, NR RLC, and NR RRC, respectively. PHY300, MAC302, RLC304, PDCP306, and RRC308 may also be referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

　Describes entities in the AS layer of E-UTRA and/or NR. An entity having some or all of the functions of the MAC layer may be called a MAC entity. An entity having some or all of the functions of the RLC layer may be called an RLC entity. An entity having some or all of the functions of the PDCP layer may be called a PDCP entity. An entity having some or all of the functions of the SDAP layer may be called an SDAP entity. An entity having some or all of the functions of the RRC layer may be called an RRC entity. The MAC entity, RLC entity, PDCP entity, SDAP entity, and RRC entity may be referred to as MAC, RLC, PDCP, SDAP, and RRC, respectively.

In addition, data provided from MAC, RLC, PDCP, and SDAP to lower layers, and/or data provided from lower layers to MAC, RLC, PDCP, and SDAP may be referred to as MAC PDU (Protocol Data Unit), RLC PDU, PDCP PDU, and SDAP PDU, respectively. Data provided from higher layers to MAC, RLC, PDCP, and SDAP, and/or data provided from MAC, RLC, PDCP, and SDAP to higher layers may be referred to as MAC SDU (Service Data Unit), RLC SDU, PDCP SDU, and SDAP SDU, respectively. In addition, a segmented RLC SDU may be referred to as an RLC SDU segment.

Here, the base station device and the terminal device exchange (transmit and receive) signals at a higher layer. For example, the base station device and the terminal device may transmit and receive RRC messages (also referred to as RRC messages, RRC information, or RRC signaling) at the Radio Resource Control (RRC) layer. The base station device and the terminal device may also transmit and receive MAC control elements at the MAC (Medium Access Control) layer. The RRC layer of the terminal device acquires system information reported from the base station device. Here, the RRC messages, system information, and/or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by the terminal device may be referred to as a higher layer parameter. In PHY layer processing, the upper layer means the upper layer seen from the PHY layer, and may mean one or more of the MAC layer, RRC layer, RLC layer, PDCP layer, NAS (Non Access Stratum) layer, etc. For example, in MAC layer processing, the upper layer may mean one or more of the RRC layer, RLC layer, PDCP layer, NAS layer, etc. Hereinafter, "A is given (provided) by the upper layer" or "A is given (provided) by the upper layer" may mean that the upper layer (mainly the RRC layer or MAC layer, etc.) of the terminal device receives A from the base station device, and the received A is given (provided) from the upper layer of the terminal device to the physical layer of the terminal device. For example, in a terminal device, "upper layer parameters are provided" may mean that an upper layer signal is received from the base station device, and the upper layer parameters included in the received upper layer signal are provided from the upper layer of the terminal device to the physical layer of the terminal device. Setting upper layer parameters in the terminal device may mean that the upper layer parameters are given (provided) to the terminal device. For example, setting upper layer parameters in a terminal device may mean that the terminal device receives an upper layer signal from a base station device and sets the received upper layer parameters in the upper layer. However, setting upper layer parameters in a terminal device may include setting default parameters that are given in advance to the upper layer of the terminal device. When explaining the transmission of an RRC message from a terminal device to a base station device, the expression "submitting a message from the RRC entity of the terminal device to a lower layer" may be used. In a terminal device, "submitting a message to a lower layer" from the RRC entity may mean submitting a message to the PDCP layer. In a terminal device, "submitting a message to a lower layer" from the RRC layer may mean submitting an RRC message to a PDCP entity corresponding to each SRB, since RRC messages are transmitted using SRBs (SRB0, SRB1, SRB2, SRB3, etc.). When the RRC entity of the terminal device receives an indication from a lower layer, the lower layer may mean one or more of the PHY layer, MAC layer, RLC layer, PDCP layer, etc.

An example of the functions of the PHY will be described. The PHY of the terminal device may have a function of receiving data transmitted from the PHY of the base station device via a downlink (DL) physical channel. The PHY of the terminal device may have a function of transmitting data to the PHY of the base station device via an uplink (UL) physical channel. The PHY may be connected to an upper MAC via a transport channel. The PHY may pass data to the MAC via the transport channel. The PHY may also be provided with data from the MAC via the transport channel. In the PHY, a Radio Network Temporary Identifier (RNTI) may be used to identify various control information.

Here, we will explain physical channels. The physical channels used for wireless communication between a terminal device and a base station device may include the following physical channels:

PBCH (Physical Broadcast CHannel)
PDCCH (Physical Downlink Control CHannel)
PDSCH (Physical Downlink Shared CHannel)
PUCCH (Physical Uplink Control CHannel)
PUSCH (Physical Uplink Shared CHannel)
PRACH (Physical Random Access CHannel)

The PBCH may be used to notify the terminal device of system information required.

In addition, in NR, the PBCH may be used to report the time index (SSB-Index) within the period of a synchronization signal block (SSB).

The PDCCH may be used to transmit (or carry) downlink control information (DCI) in downlink wireless communication (wireless communication from a base station device to a terminal device). Here, one or more DCIs (which may be referred to as DCI formats) may be defined for the transmission of the downlink control information. That is, a field for the downlink control information may be defined as a DCI and mapped to information bits. The PDCCH may be transmitted in PDCCH candidates. The terminal device may monitor a set of PDCCH candidates in the serving cell. Monitoring the set of PDCCH candidates may mean attempting to decode the PDCCH according to a certain DCI format. In addition, the terminal device may use a CORESET (Control Resource Set) to monitor the set of PDCCH candidates. The DCI format may be used for scheduling the PUSCH in the serving cell. The PUSCH may be used for transmitting user data, transmitting RRC messages described later, and the like.

The PUCCH may be used to transmit uplink control information (UCI) in uplink wireless communication (wireless communication from a terminal device to a base station device). Here, the uplink control information may include channel state information (CSI: Channel State Information) used to indicate the state of the downlink channel. The uplink control information may also include a scheduling request (SR: Scheduling Request) used to request UL-SCH (UL-SCH: Uplink Shared CHannel) resources. The uplink control information may also include a hybrid automatic repeat reQuest ACKnowledgement (HARQ-ACK).

The PDSCH may be used to transmit downlink data (DL-SCH: Downlink Shared CHannel) from the MAC layer. In the case of the downlink, the PDSCH may also be used to transmit system information (SI: System Information) and random access response (RAR: Random Access Response).

The PUSCH may be used to transmit uplink data from the MAC layer (UL-SCH: Uplink Shared CHannel) or HARQ-ACK and/or CSI together with uplink data. The PUSCH may also be used to transmit only CSI, or only HARQ-ACK and CSI. That is, the PUSCH may be used to transmit only UCI. The PDSCH or PUSCH may also be used to transmit RRC signaling (also referred to as an RRC message) and MAC CE. Here, in the PDSCH, the RRC signaling transmitted from the base station device may be common signaling for multiple terminal devices within a cell. The RRC signaling transmitted from the base station device may also be dedicated signaling (also referred to as dedicated signaling) for a certain terminal device. That is, terminal device-specific (UE-specific) information may be transmitted using dedicated signaling for a certain terminal device. The PUSCH may also be used to transmit UE capabilities in the uplink.

The PRACH may be used to transmit a random access preamble. The PRACH may also be used for initial connection establishment procedures, handover procedures, connection re-establishment procedures, synchronization (timing adjustment) for uplink transmissions, and to indicate requests for UL-SCH resources.

An example of the functions of the MAC is described below. The MAC may be called a MAC sublayer. The MAC may have the function of mapping various logical channels to corresponding transport channels. The logical channels may be identified by a logical channel identifier (Logical Channel Identity or Logical Channel ID). The MAC may be connected to the higher-level RLC via a logical channel. Depending on the type of information being transmitted, the logical channels may be divided into a control channel that transmits control information and a traffic channel that transmits user information. The logical channels may also be divided into an uplink logical channel and a downlink logical channel. The MAC may have the function of multiplexing MAC SDUs belonging to one or more different logical channels and providing them to the PHY. The MAC may also have the function of demultiplexing the MAC PDUs provided by the PHY and providing them to the higher layer via the logical channel to which each MAC SDU belongs. The MAC may also have the ability to perform error correction through HARQ (Hybrid Automatic Repeat reQuest). The MAC may also have the ability to report scheduling information. The MAC may have the ability to perform priority processing between terminal devices using dynamic scheduling. The MAC may also have the ability to perform priority processing between logical channels within a single terminal device. The MAC may have the ability to perform priority processing of overlapping resources within a single terminal device. The E-UTRA MAC may have the ability to identify Multimedia Broadcast Multicast Services (MBMS). The NR MAC may have the ability to identify Multicast/broadcast services (MBS). The MAC may have the ability to select a transport format. The MAC may have functions such as discontinuous reception (DRX) and/or discontinuous transmission (DTX), a function to execute random access (RA) procedures, a power headroom report (PHR) function to notify information on the transmittable power, a buffer status report (BSR) function to notify information on the amount of data in the transmit buffer, etc. The NR MAC may have a bandwidth adaptation (BA) function. The MAC PDU format used in the E-UTRA MAC may differ from the MAC PDU format used in the NR MAC. The MAC PDU may also include a MAC control element (MAC CE), which is an element for performing control in the MAC.

This section explains the uplink (UL) and/or downlink (DL) logical channels used in E-UTRA and/or NR.

The BCCH (Broadcast Control Channel) may be a downlink logical channel for broadcasting control information such as system information (SI).

PCCH (Paging Control Channel) may be a downlink logical channel for carrying paging messages.

The Common Control Channel (CCCH) may be a logical channel for transmitting control information between a terminal device and a base station device. The CCCH may be used when the terminal device does not have an RRC connection. The CCCH may also be used between a base station device and multiple terminal devices.

　DCCH (Dedicated Control Channel) may be a logical channel for transmitting dedicated control information in a point-to-point bidirectional manner between a terminal device and a base station device. The dedicated control information may be control information dedicated to each terminal device. DCCH may be used when the terminal device has an RRC connection.

DTCH (Dedicated Traffic Channel) may be a logical channel for transmitting user data point-to-point between a terminal device and a base station device. DTCH may be a logical channel for transmitting dedicated user data. Dedicated user data may be user data dedicated to each terminal device. DTCH may exist in both the uplink and downlink.

This section describes the mapping of logical channels and transport channels for the uplink in E-UTRA and/or NR.

The CCCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

The DCCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

The DTCH may be mapped to the uplink transport channel, UL-SCH (Uplink Shared Channel).

This section describes the mapping of logical channels and transport channels for the downlink in E-UTRA and/or NR.

The BCCH may be mapped to the downlink transport channels BCH (Broadcast Channel) and/or DL-SCH (Downlink Shared Channel).

The PCCH may be mapped to the PCH (Paging Channel), which is a downlink transport channel.

The CCCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

The DCCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

DTCH may be mapped to the downlink transport channel, DL-SCH (Downlink Shared Channel).

An example of the RLC function is described below. RLC may be called an RLC sublayer. E-UTRA RLC may have the function of segmenting and/or concatenating data provided from the upper layer PDCP and providing it to the lower layer. E-UTRA RLC may have the function of reassembling and reordering data provided from the lower layer and providing it to the upper layer. NR RLC may have the function of adding a sequence number independent of the sequence number added by PDCP to data provided from the upper layer PDCP. NR RLC may also have the function of segmenting data provided from PDCP and providing it to the lower layer. NR RLC may also have the function of reassembling data provided from the lower layer and providing it to the upper layer. RLC may also have the function of retransmitting data and/or requesting retransmission (Automatic Repeat reQuest: ARQ). RLC may also have the function of performing error correction using ARQ. The control information sent from the receiving side of RLC to the transmitting side to perform ARQ, indicating the data that needs to be retransmitted, may be called a status report. The instruction to send a status report sent from the transmitting side of RLC to the receiving side may be called a poll. RLC may also have the function of detecting data duplication. RLC may also have the function of discarding data. RLC may have three modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). TM does not split data received from the upper layer, and does not require the addition of an RLC header. The TM RLC entity is a uni-directional entity and may be configured as a transmitting TM RLC entity or a receiving TM RLC entity. In UM, data received from a higher layer may be segmented and/or combined, an RLC header may be added, etc., but data retransmission control is not required. The UM RLC entity may be a unidirectional entity or a bi-directional entity. If the UM RLC entity is a unidirectional entity, it may be configured as a transmitting UM RLC entity or as a receiving UMRLC entity. If the UM RLC entity is a bi-directional entity, the UM RRC entity may be configured as a UM RLC entity consisting of a transmitting side and a receiving side. In AM, data received from a higher layer may be segmented and/or combined, an RLC header may be added, data retransmission control is required, etc. The AM RLC entity is a bi-directional entity and may be configured as an AM RLC consisting of a transmitting side and a receiving side. Note that data provided to a lower layer in TM and/or data provided from a lower layer may be called TMD PDU. Furthermore, data provided to a lower layer in UM and/or data provided from a lower layer may be referred to as a UMD PDU. Furthermore, data provided to a lower layer in AM and/or data provided from a lower layer may be referred to as an AMD PDU. The RLC PDU format used in E-UTRA RLC may be different from the RLC PDU format used in NR RLC. Furthermore, RLC PDUs may include RLC PDUs for data and RLC PDUs for control. The RLC PDUs for data may be referred to as RLC DATA PDU (RLC Data PDU, RLC Data PDU). Furthermore, the RLC PDUs for control may be referred to as RLC CONTROL PDU (RLC Control PDU, RLC Control PDU, RLC Control PDU).

An example of the functions of PDCP is described below. PDCP may be called a PDCP sublayer. PDCP may have a function for maintaining sequence numbers. PDCP may also have a header compression/decompression function for efficiently transmitting user data such as IP packets and Ethernet frames over wireless sections. The protocol used for IP packet header compression/decompression may be called the ROHC (Robust Header Compression) protocol. The protocol used for Ethernet frame header compression/decompression may be called the EHC (Ethernet (registered trademark) Header Compression) protocol. PDCP may also have a data encryption/decryption function. PDCP may also have a data integrity protection/integrity verification function. PDCP may also have a re-ordering function. PDCP may also have a PDCP SDU retransmission function. PDCP may also have a data discard function using a discard timer. PDCP may also have a duplication function. PDCP may also have the function of discarding duplicated data received. The PDCP entity is a bidirectional entity and may consist of a transmitting PDCP entity and a receiving PDCP entity. The PDCP PDU format used in E-UTRA PDCP may differ from the PDCP PDU format used in NR PDCP. PDCP PDUs may include data PDCP PDUs and control PDCP PDUs. The data PDCP PDU may be called PDCP DATA PDU (PDCP Data PDU, PDCP Data PDU). The control PDCP PDU may be called PDCP CONTROL PDU (PDCP Control PDU, PDCP Control PDU, PDCP Control PDU).

An example of the SDAP function is described below. SDAP is a service data adaptation protocol layer. SDAP may have a function of mapping the downlink QoS flow sent from 5GC110 to the terminal device via the base station device with a data radio bearer (DRB), and/or mapping the uplink QoS flow sent from the terminal device to 5GC110 via the base station device with a DRB. SDAP may also have a function of storing mapping rule information. SDAP may also have a function of marking the QoS flow identifier (QoS Flow ID: QFI). Note that there may be an SDAP PDU for data and an SDAP PDU for control. The SDAP PDU for data may be called an SDAP DATA PDU (SDAP Data PDU, SDAP Data PDU). The SDAP PDU for control may be called an SDAP CONTROL PDU (SDAP Control PDU, SDAP Control PDU, SDAP Control PDU). There may be one SDAP entity in a terminal device for each PDU session.

An example of the functions of RRC will be described. RRC may have a broadcast function. RRC may have a paging function from EPC104 and/or 5GC110. RRC may have a paging function from eNB102 connected to gNB108 or 5GC110. RRC may also have an RRC connection management function. RRC may also have a radio bearer control function. RRC may also have a cell group control function. RRC may also have a mobility control function. RRC may also have terminal device measurement reporting and terminal device measurement reporting control functions. RRC may also have a QoS management function. RRC may also have a radio link failure detection and recovery function. RRC may use RRC messages to perform notification, paging, RRC connection management, radio bearer control, cell group control, mobility control, terminal device measurement reporting and terminal device measurement reporting control, QoS management, detection and recovery of radio link failures, etc. Note that the RRC messages and parameters used in E-UTRA RRC may differ from the RRC messages and parameters used in NR RRC.

The RRC message may be sent using the logical channel BCCH, the logical channel PCCH, the logical channel CCCH, or the logical channel DCCH. RRC messages sent using the DCCH may also be referred to as Dedicated RRC signaling, or RRC signaling.

RRC messages sent using the BCCH may include, for example, a Master Information Block (MIB), various types of System Information Blocks (SIBs), and other RRC messages. RRC messages sent using the PCCH may include, for example, paging messages, and other RRC messages.

RRC messages sent in the uplink (UL) direction using the CCCH may include, for example, an RRC setup request message (RRC Setup Request), an RRC resume request message (RRC Resume Request), an RRC reestablishment request message (RRC Reestablishment Request), an RRC system information request message (RRC System Info Request), etc. They may also include, for example, an RRC connection request message (RRC Connection Request), an RRC connection resume request message (RRC Connection Resume Request), an RRC connection reestablishment request message (RRC Connection Reestablishment Request), etc. They may also include other RRC messages.

RRC messages sent in the downlink (DL) direction using the CCCH may include, for example, an RRC connection reject message (RRC Connection Reject), an RRC connection setup message (RRC Connection Setup), an RRC connection reestablishment message (RRC Connection Reestablishment Reject), an RRC connection reestablishment rejection message (RRC Connection Reestablishment Reject), etc. They may also include, for example, an RRC reject message (RRC Reject), an RRC setup message (RRC Setup), etc. They may also include other RRC messages.

RRC signalling sent in the uplink (UL) direction using the DCCH may include, for example, a measurement report message (Measurement Report), an RRC connection reconfiguration complete message (RRC Connection Reconfiguration Complete), an RRC connection setup complete message (RRC Connection Setup Complete), an RRC connection reestablishment complete message (RRC Connection Reestablishment Complete), a security mode complete message (Security Mode Complete), and a UE capability information message (UE Capability Information). It may also include, for example, a measurement report message (Measurement Report), an RRC reconfiguration complete message (RRC Reconfiguration Complete), an RRC setup complete message (RRC Setup Complete), an RRC reestablishment complete message (RRC Resumé Complete), a security mode complete message (Security Mode Complete), a UE capability information message (UE Capability Information), etc. It may also include other RRC signaling.

The RRC signaling sent in the downlink (DL) direction using the DCCH may include, for example, an RRC connection reconfiguration message (RRC Connection Reconfiguration), an RRC connection release message (RRC Connection Release), a security mode command message (Security Mode Command), a UE capability enquiry message (UE Capability Enquiry), etc. It may also include, for example, an RRC reconfiguration message (RRC Reconfiguration), an RRC resume message (RRC Resume), an RRC release message (RRC Release), an RRC reestablishment message (RRC Reestablishment), a security mode command message (Security Mode Command), a UE capability enquiry message (UE Capability Enquiry), etc. It may also include other RRC signaling.

An example of NAS functions is described below. The NAS may have an authentication function. The NAS may also have a mobility management function. The NAS may also have a security control function.

The above-mentioned PHY, MAC, RLC, PDCP, SDAP, RRC, and NAS functions are just examples, and some or all of the functions may not be implemented. In addition, some or all of the functions of each layer may be included in another layer.

Next, the state transition of UE122 in LTE and NR will be described. When UE122 connected to EPC or 5GC has an RRC connection established, UE122 may be in the RRC_CONNECTED state. The state in which the RRC connection is established may include a state in which UE122 holds some or all of the UE context described below. The state in which the RRC connection is established may also include a state in which UE122 can transmit and/or receive unicast data. When the RRC connection is suspended, UE122 may be in the RRC_INACTIVE state. UE122 may be in the RRC_INACTIVE state when UE122 is connected to 5GC and the RRC connection is suspended. When UE122 is neither in the RRC_CONNECTED state nor in the RRC_INACTIVE state, UE122 may be in the RRC_IDLE state.

Note that when UE 122 is connected to the EPC, it does not have the RRC_INACTIVE state, but E-UTRAN may initiate suspension of the RRC connection. When UE 122 is connected to the EPC, UE 122 may transition to the RRC_IDLE state when the RRC connection is suspended, retaining the UE AS context and an identifier (resumeIdentity) used for resumption. A layer above the RRC layer of UE 122 (e.g., the NAS layer) may initiate restoration of the suspended RRC connection when UE 122 retains the UE AS context, E-UTRAN has permitted restoration of the RRC connection, and UE 122 needs to transition from the RRC_IDLE state to the RRC_CONNECTED state.

The definition of dormancy may be different for UE 122 connected to EPC 104 and UE 122 connected to 5GC 110. In addition, all or part of the procedure for UE 122 to return from dormancy may be different when UE 122 is connected to EPC (when UE 122 is dormant in RRC_IDLE state) and when UE 122 is connected to 5GC (when UE 122 is dormant in RRC_INACTIVE state).

The RRC_CONNECTED state, RRC_INACTIVE state, and RRC_IDLE state may be referred to as the connected state (connected mode), the inactive state (inactive mode), and the idle state (idle mode), respectively, or as the RRC connected state (RRC connected mode), the RRC inactive state (RRC inactive mode), and the RRC idle state (RRC idle mode).

The UE AS context held by UE122 may be information including all or part of the following: the current RRC settings, the current security context, the PDCP state including the ROHC (RObust Header Compression) state, the C-RNTI (Cell Radio Network Temporary Identifier) used in the source PCell, the cell identifier, and the physical cell identifier of the source PCell. Note that the UE AS context held by any or all of eNB102 and gNB108 may include the same information as the UE AS context held by UE122, or may include information different from the information included in the UE AS context held by UE122.

The security context may be information that includes all or part of the following: an encryption key at the AS level, a Next Hop parameter (NH), a Next Hop Chaining Counter parameter (NCC) used to derive the next hop access key, an identifier for the selected AS level encryption algorithm, and a counter used for replay protection.

Next, the serving cell will be described. In a terminal device in an RRC connected state in which CA and/or DC, which will be described later, are not set, the serving cell may be composed of one primary cell (PCell). In a terminal device in an RRC connected state in which CA and/or DC, which will be described later, are set, the multiple serving cells may refer to a set of multiple cells (set of cell(s)) composed of one or more special cells (SpCells) and one or more all secondary cells (SCells). The SpCell may support PUCCH transmission and contention-based random access (CBRA), and the SpCell may be always activated. The PCell may be a cell used in the RRC connection establishment procedure when a terminal device in an RRC idle state transitions to an RRC connected state. The PCell may also be a cell used in the RRC connection re-establishment procedure in which the terminal device re-establishes the RRC connection. The PCell may be a cell used in a random access procedure during handover. The PSCell may be a cell used in a random access procedure when adding a secondary node, which will be described later. The SpCell may be a cell used for purposes other than those mentioned above.

When a group of serving cells configured for a terminal device is composed of an SpCell and one or more SCells, it may be considered that carrier aggregation (CA) is configured for the terminal device. Furthermore, for a terminal device in which CA is configured, a cell providing additional radio resources to the SpCell may refer to an SCell.

A group of serving cells configured by RRC that uses the same timing reference cell and the same timing advance value for the cells in which the uplink is configured may be called a Timing Advance Group (TAG). A TAG including the SpCell of a MAC entity may mean a Primary Timing Advance Group (PTAG). A TAG other than the above PTAG may mean a Secondary Timing Advance Group (STAG). One or more of the TAGs may be configured for each cell group, as described below.

The following describes a cell group, which is set by a base station device for a terminal device. A cell group may be composed of one SpCell. A cell group may also be composed of one SpCell and one or more SCells. In other words, a cell group may be composed of one SpCell and, optionally, one or more SCells. A cell group may also be expressed as a set of cells (set of cell(s)).

Dual Connectivity (DC) may be a technology for performing data communication using radio resources of cell groups respectively configured by a first base station device (first node) and a second base station device (second node). When DC or MR-DC, which will be described later, is performed, a cell group may be added from the base station device to the terminal device. To perform DC, the first base station device may add a second base station device. The first base station device may be called a master node (MN). Furthermore, the cell group configured by the master node may be called a master cell group (MCG). The second base station device may be called a secondary node (SN). Furthermore, the cell group configured by the secondary node may be called a secondary cell group (SCG). The master node and the secondary node may be configured within the same base station device.

In addition, when DC is not configured, the cell group configured in the terminal device may be called MCG. In addition, when DC is not configured, the SpCell configured in the terminal device may be a PCell. In addition, NR in which DC is not configured may be called NR standalone.

Multi-Radio Dual Connectivity (MR-DC) may be a technology that performs DC using E-UTRA for MCG and NR for SCG. MR-DC may be a technology that performs DC using NR for MCG and E-UTRA for SCG. MR-DC may be a technology that performs DC using NR for both MCG and SCG. MR-DC may be a technology included in DC. An example of MR-DC that uses E-UTRA for MCG and NR for SCG may be EN-DC (E-UTRA-NR Dual Connectivity) that uses EPC in the core network, or NGEN-DC (NG-RAN E-UTRA-NR Dual Connectivity) that uses 5GC in the core network. An example of MR-DC that uses NR for MCG and E-UTRA for SCG may be NE-DC (NR-E-UTRA Dual Connectivity) that uses 5GC in the core network. Another example of MR-DC that uses NR for both MCG and SCG is NR-DC (NR-NR Dual Connectivity), which uses 5GC for the core network.

In addition, in the terminal device, one MAC entity may exist for each cell group. For example, when DC or MR-DC is configured in the terminal device, one MAC entity for the MCG and one MAC entity for the SCG may exist. The MAC entity for the MCG in the terminal device may always be established in the terminal device in all states (RRC idle state, RRC connected state, RRC inactive state, etc.). The MAC entity for the SCG in the terminal device may be created by the terminal device when the SCG is configured in the terminal device. The MAC entity for each cell group in the terminal device may be configured by the terminal device receiving RRC signaling from the base station device. When the MAC entity is associated with the MCG, the SpCell may mean the PCell. When the MAC entity is associated with the SCG, the SpCell may mean the primary SCG cell (PSCell). When the MAC entity is not associated with a cell group, the SpCell may mean the PCell. The PCell, PSCell, and SCell are serving cells. In the EN-DC and NGEN-DC, the MAC entity for the MCG may be an E-UTRA MAC entity, and the MAC entity for the SCG may be an NR MAC entity. In the NE-DC, the MAC entity for the MCG may be an NR MAC entity, and the MAC entity for the SCG may be an E-UTRA MAC entity. In the NR-DC, the MAC entities for both the MCG and SCG may be NR MAC entities. Note that the existence of one MAC entity for each cell group may be rephrased as the existence of one MAC entity for each SpCell. Also, one MAC entity for each cell group may be rephrased as one MAC entity for each SpCell.

　Explains radio bearers. When a terminal device communicates with a base station device, a wireless connection may be established by establishing a radio bearer (RB: Radio Bearer) between the terminal device and the base station device. The radio bearer used for CP may be called a signaling radio bearer (SRB: Signaling Radio Bearer). The radio bearer used for UP may be called a data radio bearer (DRB: Data Radio Bearer). Each radio bearer may be assigned a radio bearer identifier (Identity: ID). The radio bearer identifier for an SRB may be called an SRB identifier (SRB Identity, or SRB ID). The radio bearer identifier for a DRB may be called a DRB identifier (DRB Identity, or DRB ID). SRB0 to SRB2 may be defined as SRBs for E-UTRA, and other SRBs may also be defined. NR SRBs may be defined as SRB0 to SRB3, or other SRBs may be defined. SRB0 may be an SRB for RRC messages, which are transmitted and/or received using the logical channel CCCH. SRB1 may be an SRB for RRC signaling and for NAS signaling before the establishment of SRB2. The RRC signaling transmitted and/or received using SRB1 may include piggybacked NAS signaling. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and/or received using SRB1. SRB2 may be an SRB for NAS signaling and for RRC signaling including logged measurement information. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and/or received using SRB2. SRB2 may also be of lower priority than SRB1. SRB3 may be an SRB for transmitting and/or receiving specific RRC signaling when EN-DC, NGEN-DC, NR-DC, etc. are configured in the terminal device. The logical channel DCCH may be used for all RRC signaling and NAS signaling transmitted and/or received using SRB3. Other SRBs may also be provided for other uses. The DRB may be a radio bearer for user data. The logical channel DTCH may be used for RRC signaling transmitted and/or received using the DRB.

The radio bearer in the terminal device is described below. The radio bearer may include an RLC bearer. The RLC bearer may be composed of one or two RLC entities and logical channels. When there are two RLC entities in the RLC bearer, the RLC entities may be a TM RLC entity and/or a transmitting RLC entity and a receiving RLC entity in a unidirectional UM mode RLC entity. SRB0 may be composed of one RLC bearer. The RLC bearer of SRB0 may be composed of a TM RLC entity and a logical channel. SRB0 may always be established in the terminal device in all states (RRC idle state, RRC connected state, RRC inactive state, etc.). SRB1 may be established and/or configured in the terminal device by RRC signaling received from the base station device when the terminal device transitions from the RRC idle state to the RRC connected state. SRB1 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB1 may be composed of an RLC entity of AM and a logical channel. The RLC bearer of SRB2 may be established and/or configured in the terminal device by the RRC signaling received from the base station device by the terminal device in the RRC connected state with AS security activated. The SRB2 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB2 may be composed of an RLC entity of AM and a logical channel. The PDCP on the base station device side of SRB1 and SRB2 may be placed in the master node. The SRB3 may be established and/or configured in the terminal device by the RRC signaling received from the base station device by the terminal device in the RRC connected state with AS security activated when a secondary node is added or when a secondary node is changed in EN-DC, NGEN-DC, or NR-DC. The SRB3 may be a direct SRB between the terminal device and the secondary node. The SRB3 may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB3 may be composed of an AM RLC entity and a logical channel. The PDCP on the base station side of SRB3 may be placed in a secondary node. One or more DRBs may be established and/or configured in the terminal device by RRC signaling received from the base station device by the terminal device in an RRC connected state with AS security activated. The DRB may be composed of one PDCP entity and one or more RLC bearers. The RLC bearer of the DRB may be composed of an AM or UM RLC entity and a logical channel.

In addition, in MR-DC, a radio bearer in which a PDCP is placed in the master node may be called an MN terminated bearer. Also, in MR-DC, a radio bearer in which a PDCP is placed in a secondary node may be called an SN terminated bearer. Also, in MR-DC, a radio bearer in which an RLC bearer exists only in an MCG may be called an MCG bearer. Also, in MR-DC, a radio bearer in which an RLC bearer exists only in an SCG may be called an SCG bearer. Also, in DC, a radio bearer in which an RLC bearer exists in both an MCG and an SCG may be called a split bearer.

When MR-DC is configured in a terminal device, the bearer type of SRB1 and SRB2 established and/or configured in the terminal device may be MN terminated MCG bearer and/or MN terminated split bearer. Also, when MR-DC is configured in a terminal device, the bearer type of SRB3 established and/or configured in the terminal device may be SN terminated SCG bearer. Also, when MR-DC is configured in a terminal device, the bearer type of DRB established and/or configured in the terminal device may be any of all bearer types.

For an RLC bearer established and/or configured in a cell group consisting of E-UTRA, the RLC entity established and/or configured may be an E-UTRA RLC. For an RLC bearer established and/or configured in a cell group consisting of NR, the RLC entity established and/or configured may be an NR RLC. When an EN-DC is configured in a terminal device, the PDCP entity established and/or configured for an MN terminated MCG bearer may be either an E-UTRA PDCP or an NR PDCP. When an EN-DC is configured in a terminal device, the PDCP entity established and/or configured for radio bearers of other bearer types, i.e., MN terminated split bearers, MN terminated SCG bearers, SN terminated MCG bearers, SN terminated split bearers, and SN terminated SCG bearers, may be an NR PDCP. When an NGEN-DC, NE-DC, or NR-DC is configured in a terminal device, the PDCP entity established and/or configured for radio bearers of all bearer types may be an NR PDCP.

In NR, a DRB established and/or configured in a terminal device may be associated with one PDU session. One SDAP entity may be established and/or configured for one PDU session in the terminal device. The SDAP entity, PDCP entity, RLC entity, and logical channels established and/or configured in the terminal device may be established and/or configured by RRC signaling received by the terminal device from the base station device.

Note that regardless of whether MR-DC is configured, a network configuration in which the master node is eNB102 and EPC104 is the core network may be called E-UTRA/EPC. A network configuration in which the master node is eNB102 and 5GC110 is the core network may be called E-UTRA/5GC. A network configuration in which the master node is gNB108 and 5GC110 is the core network may be called NR or NR/5GC. When MR-DC is not configured, the above-mentioned master node may refer to a base station device that communicates with a terminal device.

The following describes the flow of RRC signaling transmitted and received between a terminal device and a base station device. Figure 4 is a diagram showing an example of the flow of procedures for various settings in the RRC according to this embodiment. Figure 4 shows an example of the flow when RRC signaling is sent from a base station device (eNB102 and/or gNB108) to a terminal device (UE122).

In FIG. 4, the base station device creates an RRC message (step S400). The base station device may create an RRC message in order to deliver system information (SI) or a paging message. The base station device may create an RRC message in order to transmit RRC signaling for a specific terminal device to perform a process. The process for a specific terminal device may include, for example, security settings, RRC connection reconfiguration, handover to a different RAT, RRC connection suspension, and RRC connection release. The RRC connection reconfiguration may include, for example, radio bearer control (establishment, modification, release, etc.), cell group control (establishment, addition, modification, release, etc.), measurement settings, handover, security key update, and other processes. The base station device may create an RRC message in order to respond to RRC signaling transmitted from a terminal device. Responses to RRC signaling sent from a terminal device may include, for example, a response to an RRC setup request, a response to an RRC reconnection request, a response to an RRC resume request, etc. RRC messages include information (parameters) for various information notifications and settings. These parameters may be called fields and/or information elements, and may be described using a description method called ASN.1 (Abstract Syntax Notation One).

In FIG. 4, the base station device then transmits the created RRC signaling to the terminal device (step S402). The terminal device then performs processing such as setting according to the received RRC signaling described above if necessary (step S404). After performing the processing, the terminal device may transmit RRC signaling in response to the base station device (not shown).

RRC signaling may be used for other purposes, not limited to the above examples.

In addition, in MR-DC, the RRC on the master node side may be used to transfer RRC signaling for SCG side configuration (cell group configuration, radio bearer configuration, measurement configuration, etc.) between the terminal device. For example, in EN-DC or NGEN-DC, NR RRC signaling may be included in the form of a container in E-UTRA RRC signaling transmitted and received between eNB102 and UE122. Also, in NE-DC, E-UTRA RRC signaling may be included in the form of a container in NR RRC signaling transmitted and received between gNB108 and UE122. RRC signaling for SCG side configuration may be transmitted and received between the master node and secondary node.

Note that, regardless of whether MR-DC is used, the RRC signaling for E-UTRA transmitted from the eNB102 to the UE122 may include the RRC signaling for NR, and the RRC signaling for NR transmitted from the gNB108 to the UE122 may include the RRC signaling for E-UTRA.

Next, handover in LTE and NR will be described. Handover may be a process in which a terminal device in an RRC connected state changes the serving cell from a source SpCell to a target SpCell. Handover may be part of mobility control performed by RRC. In the terminal device, handover may be performed based on RRC signaling instructing a handover received from a base station device. The RRC signaling instructing a handover may be a message regarding reconfiguration of an RRC connection including an information element (e.g., a MobilityControlInfo information element, or a ReconfigurationWithSync information element) including a parameter instructing a handover. The MobilityControlInfo information element may be referred to as a mobility control setting information element, mobility control setting, or mobility control information. The ReconfigurationWithSync information element may be referred to as a reconfiguration with synchronization information element. Additionally or alternatively, the RRC signaling indicating the handover may be a message indicating a movement to a cell of another RAT (e.g., MobilityFromEUTRACommand or MobilityFromNRCommand). The handover may be triggered by the RRC. Additionally or alternatively, the handover may be triggered by a DCI or a MAC Control Element (MAC CE). The conditions under which the terminal device can perform a handover may include some or all of the following conditions: AS security is activated, an SRB2 is established, and at least one DRB is established.

An example of a parameter included in a message regarding reconfiguration of an RRC connection will be described. FIG. 7 is an example of an ASN.1 description representing a field and/or information element included in a message regarding reconfiguration of an RRC connection in NR in FIG. 4. Not limited to FIG. 7, in the ASN.1 examples in this embodiment, <omitted> indicates that other information is omitted, not a part of the ASN.1 notation. Note that even in places without the notation <omitted>, the information element may be omitted. In this embodiment, the ASN.1 example represents an example of a parameter of RRC signaling in this embodiment, and other names and notations may be used. In addition, in the ASN.1 example, in order to avoid complicating the explanation, only an example of main information closely related to this embodiment is shown. Note that in each embodiment, the parameters described in ASN.1 may not be distinguished between fields, information elements, etc., and may all be expressed as information elements. In each embodiment, the fields and/or information elements described in ASN.1 included in RRC signaling may be referred to as information, and in addition to or instead of that, may be referred to as parameters. The message regarding reconfiguration of the RRC connection may be an RRC reconfiguration message in NR. Also, the message regarding reconfiguration of the RRC connection may be an RRC connection reconfiguration message in E-UTRA.

In FIG. 7, a message regarding reconfiguration of an RRC connection may include an information element (CellGroupConfig information element) used for setting, changing, releasing, etc., a cell group of an NR MCG or SCG. A message regarding reconfiguration of an RRC connection may independently include a CellGroupConfig information element for setting an MCG and a CellGroupConfig information element for setting an SCG. The CellGroupConfig information element may be referred to as a cell group setting information element or a cell group setting.

The CellGroupConfig information element may include a cellGroupId information element as identifier information for identifying this cell group.

The CellGroupConfig information element may include an RLC-BearerConfig information element as information used to configure the RLC entity.

The CellGroupConfig information element may include a MAC-CellGroupConfig information element as information used to configure MAC parameters in that cell group.

The CellGroupConfig information element may include a PhysicalCellGroupConfig information element as information used to configure PHY (L1) parameters specific to that cell group.

The CellGroupConfig information element may include an SpCellConfig information element as information used to set parameters for the SpCell of the cell group. The SpCellConfig information element may be referred to as an SpCell configuration information element or an SpCell configuration.

The CellGroupConfig information element may include a SCellConfig information element for each SCell as information used to configure parameters for one or more SCells in the cell group. The SCellConfig information element may be referred to as a SCell configuration information element or a SCell configuration.

The MAC-CellGroupConfig information element may include a TAG-Config information element as information used to configure parameters related to the TAG. The TAG-Config information element may include one or more TAG identifiers (TAG-Id) configured in the terminal device and the value of the time adjustment timer corresponding to the TAG identifiers.

The SpCellConfig information element may include a ServingCellConfig information element as information used to configure terminal device specific (UE specific) parameters related to the SpCell. The SCellConfig information element may include this ServingCellConfig information element as information used to configure terminal device specific (UE specific) parameters related to the SCell. The CellGroupConfig information element may include a ServingCellConfig information element for each serving cell to configure terminal device specific parameters related to the SpCell and each SCell. Each ServingCellConfig information element may include a TAG identifier (TAG-Id) indicating which TAG in the cell group the serving cell belongs to. The ServingCellConfig information element may include not only terminal device specific parameters but also cell specific parameters.

Each ServingCellConfig information element may include an initialDownlinkBWP indicating a BWP-DownlinkDedicated information element as a terminal device specific setting for the initial downlink BWP. The BWP-DownlinkDedicated information element is also referred to as a downlink BWP dedicated setting. Additionally or alternatively, each ServingCellConfig information element may include some or all of the first active downlink BWP identifier (firstActiveDownlinkBWP-Id), the BWP inactivity timer (bwp-InactivityTimer), and the identifier of the default downlink BWP (defaultDownlinkBWP-Id).

The ServingCellConfig information element for configuring terminal device-specific parameters for each SCell may include a DormantBWP-Config information element as a dormant BWP configuration for the SCell. The DormantBWP-Config information element is also referred to as a dormant BWP configuration. For example, the DormantBWP-Config information element may include a dormant BWP identifier (dormantBWP-Id).

The SCellConfig information element may include an RRC parameter (sCellState) indicating whether the SCell is activated or not when the SCell is configured. The sCellState is also referred to as the SCell state configuration. For example, if the SCellConfig information element includes sCellState, or if the sCellState included in the SCellConfig information element is set to activated, the MAC entity of the terminal device may activate the SCell, and in addition or instead, the RRC layer of the terminal device may configure a lower layer (such as a MAC entity) to consider that the SCell is activated. In addition or instead, for example, if the SCellConfig information element does not include sCellState, the MAC entity of the terminal device may deactivate the SCell, and in addition or instead, the RRC layer of the terminal device may configure a lower layer (such as a MAC entity) to consider that the SCell is deactivated.

The ServingCellConfig information element for configuring terminal device specific parameters for each SCell for which PUCCH is not configured may include a SCell inactivity timer.

Each ServingCellConfig information element may include an UplinkConfig information element as an uplink configuration. The UplinkConfig information element is also referred to as an uplink configuration. The UplinkConfig information element may include an initialUplinkBWP indicating a BWP-UplinkDedicated information element as a terminal device specific configuration for an initial uplink BWP. The BWP-UplinkDedicated information element is also referred to as an uplink BWP dedicated configuration. Additionally or alternatively, the UplinkConfig information element may include a first active uplink BWP identifier (firstActiveUplinkBWP-Id).

The SpCellConfig information element may include a ReconfigurationWithSync information element as information including parameters necessary for processing synchronous reconfiguration from the source SpCell to the target SpCell. The ReconfigurationWithSync information element may be the synchronous reconfiguration information element described above. If the SpCellConfig information element of the MCG includes a ReconfigurationWithSync information element, the synchronous reconfiguration processing to the target SpCell may be a handover. If the SpCellConfig information element of the SCG includes a ReconfigurationWithSync information element, the synchronous reconfiguration processing to the target SpCell may be a PSCell addition or a PSCell change.

The ReconfigurationWithSync information element and the SCellConfig information element may include a ServingCellConfigCommon information element as information used to configure cell-specific parameters of the serving cell. The ServingCellConfigCommon information element may include parameters that are typically obtained from the SSB, MIB, or one or more SIBs of the cell when the terminal device accesses the cell from the idle state.

The ReconfigurationWithSync information element may include, for example, information on the value of the C-RNTI used in the cell group of the target SpCell. The ReconfigurationWithSync information element may include, for example, information required to execute a non-contention random access procedure in the target SpCell.

Figure 8 shows an example of an ASN.1 description representing fields and/or information elements related to the ServingCellConfigCommon information element contained in the SCellConfig information element and the ReconfigurationWithSync information element in the SpCellConfig information element in Figure 7.

The ServingCellConfigCommon information element may include the physical cell identifier (physCellId) of the cell.

The ServingCellConfigCommon information element may include a DownlinkConfigCommon information element as information that provides cell-specific (cell-common) downlink parameters. The DownlinkConfigCommon information element is also referred to as downlink common configuration.

The ServingCellConfigCommon information element may include an UplinkConfigCommon information element as information that provides cell-specific (cell-common) uplink parameters. The UplinkConfigCommon information element is also referred to as uplink common configuration.

The ServingCellConfigCommon information element may contain the value of N_{TA,offset} that applies to all uplink transmissions in that cell.

The DownlinkConfigCommon information element may include a FrequencyInfoDL information element as basic information regarding the downlink carrier and transmission on the downlink carrier. For example, the FrequencyInfoDL information element may include frequency information of the SSB.

The DownlinkConfigCommon information element may include initialDownlinkBWP, which indicates the BWP-DownlinkCommon information element as the initial downlink BWP setting for that cell. Additionally or alternatively, the DownlinkConfigCommon information element may include initialDownlinkBWP-RedCap, which indicates the BWP-DownlinkCommon information element to be used by one or more performance-limited terminals (RedCap UEs) instead of initialDownlinkBWP. The BWP-DownlinkCommon information element is also referred to as the downlink BWP common setting.

The BWP-DownlinkCommon information element may include a BWP information element as information for setting generic parameters of the BWP.

The BWP-DownlinkCommon information element may include a PDCCH-ConfigCommon information element as information for setting cell-specific parameters for the PDCCH of this BWP. The PDCCH-ConfigCommon information element is also referred to as a PDCCH common configuration.

The BWP-DownlinkCommon information element may include a PDSCH-ConfigCommon information element as information for setting cell-specific parameters for the PDSCH of this BWP. The PDSCH-ConfigCommon information element is also referred to as the PDSCH common configuration.

The PDCCH-ConfigCommon information element may include a SearchSpaceZero information element as information for setting parameters of the common search space (CSS) #0. This SearchSpaceZero information element may be included in the PDCCH-ConfigCommon information element only if the BWP is an initial downlink BWP.

The PDCCH-ConfigCommon information element may include a ControlResourceSetZero information element as information for setting parameters of the common CORESET#0 used in one or more common search spaces and one or more UE-specific search spaces. This ControlResourceSetZero information element may be included in the PDCCH-ConfigCommon information element only if the BWP is an initial downlink BWP.

The PDCCH-ConfigCommon information element may include a ControlResourceSet information element as information for setting additional common CORESET parameters.

The PDCCH-ConfigCommon information element may include a list (commonSearchSpaceList) of information elements (SearchSpace information elements) that indicate the configuration of one or more additional CSSs.

The PDCCH-ConfigCommon information element may include information (searchSpaceSIB1) indicating which CSS in the commonSearchSpaceList the search space setting for the system information (SIB1) is.

The PDCCH-ConfigCommon information element may include information (searchSpaceOtherSystemInformation) indicating which CSS in the commonSearchSpaceList the search space setting for system information (SIB2 and later) is.

The PDCCH-ConfigCommon information element may include information (pagingSearchSpace) indicating which CSS in the commonSearchSpaceList is used to set the search space for paging messages.

The UplinkConfigCommon information element may include a FrequencyInfoUL information element for configuring the absolute uplink frequency and multiple subcarrier specific virtual carriers. For example, the FrequencyInfoUL information element may include information indicating the maximum transmit power.

The UplinkConfigCommon information element may include initialUplinkBWP, which indicates the BWP-UplinkCommon information element as the initial uplink BWP setting for that cell. Additionally or alternatively, the UplinkConfigCommon information element may include initialUplinkBWP-RedCap, which indicates the BWP-UplinkCommon information element to be used by one or more performance-limited terminals (RedCap UEs) instead of initialUplinkBWP. The BWP-UplinkCommon information element is also referred to as the uplink BWP common setting.

The BWP-UplinkCommon information element may include a BWP information element as information for setting generic parameters of the BWP.

The BWP-UplinkCommon information element may include a PUCCH-ConfigCommon information element as information for setting cell-specific parameters for the PUCCH of this BWP. The PUCCH-ConfigCommon information element is also referred to as PUCCH common configuration.

The BWP-UplinkCommon information element may include a PUSCH-ConfigCommon information element as information for setting cell-specific parameters for the PUSCH of this BWP. The PUSCH-ConfigCommon information element is also referred to as a PUSCH common configuration.

The BWP-UplinkCommon information element may include a RACH-ConfigCommon information element as information for setting cell-specific random access parameters. The RACH-ConfigCommon information element is also referred to as RACH common configuration.

Note that each of the above information elements may include other information in addition to the information described above.

The RRC reconfiguration procedure will be described. The RRC reconfiguration procedure may be a procedure for a terminal device to modify an RRC connection based on a message related to reconfiguration of the RRC connection. The purpose of the RRC reconfiguration procedure may be some or all of the following (A) to (F).
(A) Establishing, modifying and/or releasing radio bearers; (B) Performing synchronized reconfiguration; (C) Setting up, modifying and/or releasing measurements; (D) Adding, modifying and/or releasing SCells and cell groups; (E) Adding, modifying and/or releasing conditional handover (CHO) configuration; (F) Adding, modifying and/or releasing conditional PSCell change (CPC) or conditional PSCell addition (CPA) configuration.

The base station device (network) may initiate an RRC reconfiguration procedure for a terminal device in the RRC_CONNECTED state. Note that "the base station device initiates an RRC reconfiguration procedure for a terminal device" may be rephrased as "the base station device sends a message regarding the reconfiguration of the RRC connection to the terminal device."

When the terminal device receives a message regarding reconfiguration of an RRC connection or when performing a conditional reconfiguration (CHO, CPA, or CPC), it may perform some or all of the following processes RRP (A) to (D).
(Processing RRP)
(A) If the message regarding the RRC connection reconfiguration includes a cell group configuration of the MCG, perform cell group configuration using the cell group configuration. In addition, if the cell group configuration includes an SpCell configuration including a synchronized reconfiguration information element, perform synchronized reconfiguration.
(B) If the message regarding the RRC connection reconfiguration includes a cell group configuration of the SCG, perform cell group configuration using the cell group configuration, and if the cell group configuration includes an SpCell configuration with a synchronized reconfiguration information element, perform synchronized reconfiguration.
(C) If the message regarding the reconfiguration of the RRC connection includes information regarding conditional reconfiguration, the information regarding the conditional reconfiguration is used to perform a configuration process for the conditional reconfiguration.
(D) Submit an RRC reconfiguration complete message to the lower layers (PHY, MAC, etc.) of the terminal device for transmission using the new settings.

In order to execute synchronous reconfiguration, the terminal device may perform some or all of the following processes RWS (A) to (E). "Executing synchronous reconfiguration" may be rephrased as "implementing synchronous reconfiguration" or "triggering synchronous reconfiguration."
(Processing RWS)
(A) If the frequencyInfoDL information element is included in the synchronization-assisted reconfiguration information element, it is determined that the target SpCell is a cell that is located at the SSB frequency indicated in the frequencyInfoDL information element and is indicated by the physical cell identifier included in the synchronization-assisted reconfiguration information element. If the frequencyInfoDL information element is not included in the synchronization-assisted reconfiguration information element, it is determined that the target SpCell is a cell that is located at the same SSB frequency as the source SpCell and is indicated by the physical cell identifier included in the synchronization-assisted reconfiguration information element.
(B) Initiate downlink synchronization to the target SpCell.
(C) If the timing information required for the random access procedure is not held, the MIB of the target SpCell is obtained.
(C) Reset the MAC entity of the cell group that is the target of synchronized reconfiguration.
(D) The value of the new UE identifier (newUE-Identity) included in the synchronized reconfiguration information element is applied as the C-RNTI for the cell group that is the target of the synchronized reconfiguration.
(E) Configure the RRC lower layers (PHY, etc.) according to the SpCell common settings.

Conditional reconfiguration will now be described. The network configures one or more conditional reconfiguration information elements for the terminal device, which causes the network to configure, for the terminal device, candidate target SpCells that correspond to the conditional reconfiguration information elements, respectively. The terminal device evaluates the state of the configured candidate target SpCells. The terminal device performs the evaluation and applies one of the conditional RRC reconfiguration information elements included in the conditional reconfiguration information elements associated with one or more candidate target SpCells that satisfy the execution conditions. The terminal device may also hold a list of entries (VarConditionalReconfig), described later, for conditional reconfiguration.

The conditional reconfiguration may be referred to as a conditional handover if the candidate target SpCell is an SpCell (i.e., a PCell) of an MCG. The conditional reconfiguration may also be referred to as a conditional PSCell addition and/or conditional PSCell change if the candidate target SpCell is an SpCell (i.e., a PSCell) of an SCG.

When the terminal device receives information about conditional reconfiguration (e.g., a conditional reconfiguration information element) as a setting process for conditional reconfiguration, and the information about the conditional reconfiguration includes an entry deletion list (condReconfigToRemoveList), the terminal device may delete (remove) the conditional reconfiguration settings specified in the entry deletion list from the settings held by the terminal device. Specifically, when an entry identifier (condReconfigId) included in the entry deletion list is included in the list of entries held by the terminal device, the terminal device may delete the entry corresponding to the entry identifier from the list of entries held by the terminal device.

In the following description, the list of conditional reset entries held by the terminal device is also simply referred to as the entry list. In other words, in the following description, "entry list" refers to the list of conditional reset entries held by the terminal device unless otherwise specified. The conditional reset entry list may also be a variable named VarConditionalReconfig. The entry identifier is also simply referred to as the entry identifier.

If the information regarding conditional reconfiguration includes an entry add/modify list (condReconfigToAddModList), the terminal device may add or modify the conditional reconfiguration settings included in the entry add/modify list to the settings held by the terminal device as a conditional reconfiguration configuration process. The entry add/modify list may be a list of one or more conditional reconfiguration information elements. Each entry may be configured by a conditional reconfiguration information element. The conditional reconfiguration information element may include an entry identifier, an execution condition, and a conditional RRC reconfiguration information element.

Specifically, when each entry identifier included in the entry addition/modification list exists in an entry of the entry list, the terminal device may perform the following processing (A) and/or (B).
(A) If an entry included in the addition/modification list of an entry includes an execution condition (condExecutionCond), the execution condition of an entry in the entry list that matches the entry identifier of this entry is replaced with the execution condition included in the addition/modification list of that entry.
(B) If an entry included in the additional modification list of an entry includes a conditional RRC reconfiguration information element (condRRCReconfig), the conditional RRC reconfiguration information element in the entry list that matches the entry identifier of this entry is replaced with the conditional RRC reconfiguration information element included in the additional modification list of that entry.

In addition, if an entry identifier included in the entry addition/modification list is not included in the entry list, the terminal device may add to the entry list a new entry corresponding to the entry identifier not included in the entry list.

Note that the entry deletion list may be a list of one or more entry identifiers to be deleted. Each entry included in the entry addition modification list includes an entry identifier and may additionally include an execution condition and/or a conditional RRC reconfiguration information element. Each entry may be associated with one of one or more candidate target SpCells. The entry identifier may be an identifier used to identify each entry of the CHO, CPA, and CPC. The entry list may include one or more entries. Each entry may include one entry identifier, one or more execution conditions, and one conditional RRC reconfiguration information element. If the entry list held by the terminal device does not include an entry, the terminal device may hold an empty list. The execution condition may be a condition that needs to be satisfied to trigger the execution of the conditional reconfiguration. The conditional RRC reconfiguration information element may be a message regarding the reconfiguration of the RRC connection that is applied when the execution condition is satisfied. The message regarding the reconfiguration of the RRC connection may be a message used to connect to the candidate target SpCell.

The terminal device may evaluate the execution conditions of the entries included in the entry list held by the terminal device. If the entry list held by the terminal device is empty or if the terminal device does not hold an entry list, it is not necessary to evaluate the execution conditions.

Executing a conditional reconfiguration may mean that the terminal device evaluates the execution conditions of entries included in an entry list held by the terminal device, and if one or more execution conditions are satisfied, applies a conditional RRC reconfiguration information element included in the entry that includes the execution condition. Applying a conditional RRC reconfiguration information element may mean executing an RRC reconfiguration procedure using the conditional RRC reconfiguration information element.

If there are multiple entries that satisfy the execution condition, the terminal device may select one entry from the multiple entries that satisfy the execution condition and apply the conditional RRC reconfiguration information element of the selected entry.

When a reset of the MAC entity is requested from an upper layer (e.g., RRC), the MAC entity of the terminal device may perform part or all of (A) to (O) of the following processes MR. The reset of the MAC entity may be simply referred to as a MAC reset. When a partial reset of the MAC entity is requested from an upper layer (e.g., RRC), the MAC entity of the terminal device may perform part or all of (A) to (O) of the following processes MR. The partial reset of the MAC entity may be simply referred to as a partial MAC reset. The process performed in the partial MAC reset may be a process in which only a part of the process performed in the MAC reset is performed. The process performed in the partial MAC reset may be a process in which some of the process performed in the MAC reset is not performed. The MAC entity of the terminal device may perform a MAC reset based on an instruction from the RRC entity of the terminal device to the MAC entity of the terminal device to perform a MAC reset. Additionally or alternatively, the MAC entity of the terminal device may perform a partial MAC reset based on an instruction from the RRC entity of the terminal device to the MAC entity of the terminal device to perform a partial MAC reset.

(Processing MR)
(A) The parameter Bj set for each logical channel is initialized to 0.
(B) Stop all running timers, except for some timers.
(C) If one or more time adjustment timers are set, all of those time adjustment timers are considered to have expired, and processing for the expiration of a time adjustment timer is carried out.
(D) Set the New Data Indicator (NDI) value of all uplink HARQ processes to 0.
(E) If there is a random access procedure in progress, stop the random access procedure.
(F) If there are explicitly signalled contention-free random access (CFRA) resources for 4-step and 2-step RA types, discard those resources.
(G) Flush the Msg3 buffer.
(H) Flush the MSGA buffer.
(I) If any Scheduling Request (SR) procedure has been triggered, cancel the SR procedure.
(J) If a Buffer Status Reporting (BSR) procedure has been triggered, cancel the BSR procedure.
(K) If any Power Headroom Reporting (PHR) procedure has been triggered, cancel the PHR procedure.
(L) Flush the soft buffers of all downlink HARQ processes.
(M) If any Beam Failure Reporting (BFR) has been triggered, cancel the BFR.
(N) If there is a Temporary C-RNTI, release the temporary C-RNTI.
(O) Reset all BFI_COUNTERs.

The following describes cell activation and deactivation. In a terminal device communicating using Dual Connectivity, a Master Cell Group (MCG) and a Secondary Cell Group (SCG) are configured by a message regarding the reconfiguration of the RRC connection described above. Each cell group may be composed of a special cell (SpCell) and zero or more other cells (secondary cells: SCell). The SpCell of an MCG is also referred to as a PCell. The SpCell of an SCG is also referred to as a PSCell. Cell deactivation does not apply to SpCells, but may apply to SCells.

Activation and deactivation of a cell may be processed by a MAC entity that exists for each cell group. An SCell configured in a terminal device may be activated and/or deactivated by some or all of the following (A) to (C).
(A) Reception of a MAC CE that activates/deactivates an SCell (MAC CE named SCell Activation/Deactivation MAC CE or Enhanced SCell Activation/Deactivation MAC CE) (B) An SCell inactivity timer that is set for each SCell for which a PUCCH is not configured (C) An RRC parameter (sCellState) that is set for each SCell configured in the terminal device

Specifically, the MAC entity of the terminal device may perform the following processing (AD) for each SCell configured in the cell group.

(Processing AD)
If the RRC parameter (sCellState) configured for the SCell during SCell configuration is set to activated, or if a MAC CE for activating the SCell (SCell Activation/Deactivation MAC CE indicating that the SCell is to be activated, or Enhanced SCell Activation/Deactivation MAC CE indicating that the SCell is to be activated) is received, the MAC entity of the UE 122 performs the process (AD-1). Otherwise, if a MAC CE for deactivating the SCell (SCell Activation/Deactivation MAC CE indicating that the SCell is to be deactivated, or Enhanced SCell Activation/Deactivation MAC CE indicating that the SCell is to be deactivated) is received, or the SCell inactivation timer expires in the activated SCell, or the SCG associated with the activated SCell is deactivated, the MAC entity of the UE 122 performs the process (AD-2). Additionally or alternatively, if an uplink grant or downlink assignment is indicated by the PDCCH of an activated SCell, or if an uplink grant or downlink assignment for an activated SCell is indicated by the PDCCH of a serving cell, or if a MAC PDU is transmitted in a configured uplink grant or received in a configured downlink assignment, the MAC entity of the UE 122 restarts the SCell inactivity timer associated with that SCell. If the SCell is deactivated, the MAC entity of the UE 122 performs a process (AD-3).

(Process AD-1)
If the SCell was deactivated in NR before receiving a MAC CE activating the SCell or if the RRC parameter (sCellState) configured for the SCell during SCell configuration is set to activated, the MAC entity of the UE 122 performs some or all of steps (AD-1A), (AD-1B) and (AD-1C). Additionally or alternatively, the MAC entity of the UE 122 starts or restarts (if already started) the SCell inactivity timer associated with the SCell. If the Active DL BWP is not a Dormant BWP, the MAC entity of the UE 122 (re)initializes all suspended configured uplink grants of grant type 1 associated with the SCell according to a stored configuration, if any, and additionally or alternatively triggers a PHR.

(Process AD-1A)
If the BWP indicated by the first active downlink BWP identifier (firstActiveDownlinkBWP-Id) is not set to a dormant BWP, the MAC entity of UE 122 activates the SCell and performs some or all of the following (A) to (E).
(A) Transmit a sounding reference signal (SRS) on this SCell.
(B) Report the CSI for this SCell.
(C) Monitor the PDCCH of this SCell.
(D) Monitor the PDCCH for this SCell (if scheduling for this SCell is performed in another serving cell).
(E) If PUCCH is configured, transmit PUCCH on this SCell.

(Process AD-1B)
If the BWP indicated by the firstActiveDownlinkBWP-Id is configured as a Dormant BWP, the MAC entity of the UE 122 stops the BWP inactivity timer of this serving cell if it is running.

(Process AD-1C)
The downlink BWP and the uplink BWP indicated by the first active downlink BWP identifier (firstActiveDownlinkBWP-Id) and the first active uplink BWP identifier (firstActiveUplinkBWP-Id), respectively, are activated.

(Process AD-2)
The MAC entity of UE 122 performs some or all of the following (A) to (H).
(A) This SCell is deactivated.
(B) Stop the SCell inactivity timer associated with this SCell.
(C) Stop the BWP inactivity timer associated with this SCell.
(D) Deactivate all Active BWPs associated with this SCell.
(E) Clear all configured downlink assignments and/or all configured uplink grants of grant type 2 associated with this SCell.
(F) Clear all PUSCH resources for semi-persistent CSI reporting associated with this SCell.
(G) Suspend all configured uplink grants of grant type 1 associated with this SCell.
(H) Flush the HARQ buffer associated with this SCell.

(Process AD-3)
The MAC entity of UE 122 performs some or all of the following (A) to (D).
(A) Do not transmit SRS on this SCell.
(B) Do not report CSI for this SCell.
(C) Do not transmit PUCCH, UL-SCH, and/or RACH on this SCell.
(D) Do not monitor the PDCCH of this SCell and/or the PDCCH for this SCell.

As described above, the MAC entity performs processing (AD) to activate and deactivate the SCell.

Also, when an SCell is added as described above, the initial state of the SCell may be configured by RRC signaling.

Here, the SCell deactivation timer will be explained. For an SCell for which PUCCH is not configured, the value of the SCell deactivation timer (information regarding the time at which the timer is considered to have expired) may be notified by RRC signaling. For example, if information indicating 40 ms as the value of the SCell deactivation timer is notified by RRC signaling, in the above process (AD), the timer is considered to have expired when the notified time (here, 40 ms) has elapsed since the timer was started or restarted without being stopped. The SCell deactivation timer may also be a timer named sCellDeactivationTimer.

Here, we will explain the band portion (BWP).

A BWP may be a part or all of the bandwidth of the serving cell. A BWP may also be referred to as a carrier BWP. One or more BWPs may be configured in a terminal device. A BWP may be configured by information included in system information associated with a synchronization signal detected in the initial cell search. A BWP may also be a frequency bandwidth associated with the frequency at which the initial cell search is performed. A BWP may also be configured by RRC signaling (e.g., Dedicated RRC signaling). A downlink BWP (DL BWP) and an uplink BWP (UL BWP) may also be configured separately. One or more uplink BWPs may be associated with one or more downlink BWPs. Furthermore, the correspondence between the uplink BWP and the downlink BWP may be a default correspondence, or may be correspondence based on RRC signaling (e.g., Dedicated RRC signaling), or may be correspondence based on physical layer signaling (e.g., Downlink Control Information (DCI) notified on the downlink control channel), or may be a combination of these. Furthermore, a CORESET may be set in the downlink BWP.

A BWP may consist of a group of consecutive physical radio blocks (PRBs: Physical Resource Blocks). Furthermore, parameters of the BWP of each component carrier (one or multiple BWPs) may be set for a connected terminal device. The parameters of the BWP of each component carrier may include some or all of the following: (A) cyclic prefix type, (B) subcarrier spacing, (C) frequency location of the BWP (e.g., the start location or center frequency location of the BWP on the low frequency side) (for example, the ARFCN may be used for the frequency location, or an offset from a specific subcarrier of the serving cell may be used. The offset unit may be a subcarrier unit or a resource block unit. Both the ARFCN and the offset may be set.), (D) bandwidth of the BWP (e.g., the number of PRBs), (E) resource configuration information of the control signal, (F) center frequency location of the SS block (for example, the ARFCN may be used for the frequency location, or an offset from a specific subcarrier of the serving cell may be used. The offset unit may be a subcarrier unit or a resource block unit. Both the ARFCN and the offset may be set.). The resource configuration information of the control signal may be included in the configuration of the BWP of at least some or all of the PCell and/or PSCell.

A terminal device may transmit and receive in an Active BWP among one or more configured BWPs. One or more BWPs may be configured in a serving cell associated with the terminal device. Among one or more BWPs configured for a serving cell associated with the terminal device, at a given time, up to one uplink BWP and/or up to one downlink BWP may be configured to be the Active BWP. An Active BWP in the downlink is also referred to as an Active DL BWP. An Active BWP in the uplink is also referred to as an Active UL BWP. Furthermore, among one or more BWPs configured in a terminal device, a BWP that is not an Active BWP may be referred to as an Inactive BWP.

Next, we will explain the activation/inactivation of BWP. Activation of BWP may mean activating a BWP or activating an inactive BWP. Inactivation of BWP may mean inactivating a BWP or inactivating an active BWP. BWP switching in a serving cell is used to activate an inactive BWP and inactivate an active BWP.

BWP switching is controlled by the PDCCH indicating a downlink assignment or uplink grant, the BWP inactivity timer, RRC signalling or the MAC entity itself for initiation of a random access procedure. Active BWP in the serving cell is indicated by RRC or PDCCH.

Next, the BWP inactivity timer will be described. For each activated serving cell for which the BWP inactivity timer is set, the MAC entity performs the following (A). The BWP inactivity timer may be a timer named bwp-InactivityTimer.
(A) If any of the following (A-1) through (A-4) is met, the MAC entity performs the following (B) and (D).
(A-1) The default downlink BWP identifier (defaultDownlinkBWP-Id) is set, the Active DL BWP is not the BWP indicated by the defaultDownlinkBWP-Id, and the Active DL BWP is not the BWP indicated by the dormant BWP identifier (dormantBWP-Id).
(A-2) The UE is not a performance-limited terminal (RedCap UE), the default downlink BWP identifier (defaultDownlinkBWP-Id) is not set, the Active DL BWP is not the initialDownlinkBWP, and the Active DL BWP is not the BWP indicated by the dormant BWP identifier (dormantBWP-Id).
(A-3) The UE is a performance-limited terminal (RedCap UE), the identifier of the default downlink BWP (defaultDownlinkBWP-Id) is not set, the initial downlink BWP for the performance-limited terminal (initialDownlinkBWP-RedCap) is not set, and the Active DL BWP is not the initialDownlinkBWP.
(A-4) The UE is a performance-limited terminal (RedCap UE), the identifier of the default downlink BWP (defaultDownlinkBWP-Id) is not set, an initial downlink BWP for the performance-limited terminal (initialDownlinkBWP-RedCap) is set, and the Active DL BWP is not initialDownlinkBWP-RedCap.
(B) If a PDCCH addressed to the C-RNTI or CS-RNTI is received indicating a downlink assignment or uplink grant for an Active BWP, or if a PDCCH addressed to the C-RNTI or CS-RNTI is received indicating a downlink assignment or uplink grant for an Active BWP, or if a MAC PDU is sent with a configured uplink grant or a MAC PDU is received with a configured downlink assignment, the MAC entity performs the following (C).
(C) If no random access procedure associated with this serving cell is ongoing or an ongoing random access procedure associated with this serving cell is successfully completed by reception of a PDCCH addressed to the C-RNTI, start or restart the BWP inactivity timer associated with the Active DL BWP.
(D) If the BWP inactivity timer associated with an Active DL BWP expires, the MAC entity performs (E) below.
(E) If defaultDownlinkBWP-Id is set, the MAC entity performs BWP switching to the BWP indicated by this defaultDownlinkBWP-Id. If not, the MAC entity performs the next (F).
(F) If the UE is a performance-limited terminal (RedCap UE) and an initial downlink BWP for a performance-limited terminal (initialDownlinkBWP-RedCap) is configured, perform BWP switching to this initialDownlinkBWP-RedCap; otherwise, perform BWP switching to the initialDownlinkBWP.

Furthermore, if the MAC entity receives a PDCCH for BWP switching and switches the Active DL BWP, it performs the following (A).
(A) If any of the following (A-1) to (A-4) is met, start or restart the BWP inactivity timer associated with the Active DL BWP.
(A-1) A default downlink BWP identifier (defaultDownlinkBWP-Id) is set, and the MAC entity switches to a downlink BWP that is not indicated in either the defaultDownlinkBWP-Id or the dormant BWP identifier (dormantBWP-Id).
(A-2) The UE is not a performance-limited terminal (RedCap UE), the default downlink BWP identifier (defaultDownlinkBWP-Id) is not set, and the MAC entity switches to a downlink BWP that is not the initialDownlinkBWP and is not indicated by the dormant BWP identifier (dormantBWP-Id).
(A-3) The UE is a performance-limited terminal (RedCap UE), the identifier of the default downlink BWP (defaultDownlinkBWP-Id) is not set, the initial downlink BWP for the performance-limited terminal (initialDownlinkBWP-RedCap) is not set, and the MAC entity switches to a downlink BWP other than the initialDownlinkBWP.
(A-4) The UE is a performance-limited terminal (RedCap UE), the identifier of the default downlink BWP (defaultDownlinkBWP-Id) is not set, an initial downlink BWP for the performance-limited terminal (initialDownlinkBWP-RedCap) is set, and the MAC entity switches to a downlink BWP other than initialDownlinkBWP-RedCap.

In each active serving cell in which a BWP is configured, the MAC entity shall perform some or all of the following (A) to (H) if the BWP is active (Active BWP) and the Active DL BWP in that serving cell is not a dormant BWP:
(A) Transmit UL-SCH with that BWP.
(B) If a PRACH occasion is configured, send a RACH in that BWP.
(C) Monitor the PDCCH in that BWP.
(D) If PUCCH is configured, transmit PUCCH in that BWP.
(E) Report the CSI in that BWP.
(F) If SRS is configured, send SRS in that BWP.
(G) Receive DL-SCH on that BWP.
(H) (re)initialize all suspended configured uplink grants of grant type 1 in that Active BWP according to the stored configuration, if any.

If the BWP is activated (Active BWP) and the Active DL BWP in its serving cell is a dormant BWP, the MAC entity performs some or all of the following (A) to (L).
(A) Stop this serving cell's BWP inactivity timer, if it is running.
(B) Do not monitor the PDCCH in that BWP.
(C) Do not monitor the PDCCH for that BWP.
(D) DL-SCH is not received on that BWP.
(E) Do not report CSI in that BWP, and report CSI excluding aperiodic CSI for that BWP.
(F) Do not send SRS in that BWP.
(G) Do not transmit UL-SCH in that BWP.
(H) Do not send a RACH in that BWP.
(I) Do not transmit PUCCH in that BWP.
(J) Clear all configured downlink assignments and/or all configured uplink grants of grant type 2 associated with that SCell.
(K) Suspend all configured uplink grants of grant type 1 associated with that SCell.
(L) If beam failure is detected, perform beam failure detection and beam failure recovery for that SCell.

A MAC entity shall, if a BWP is deactivated, do some or all of the following:
(A) Do not transmit UL-SCH in that BWP.
(B) Do not send a RACH in that BWP.
(C) Do not monitor the PDCCH in that BWP.
(D) Do not transmit PUCCH in that BWP.
(E) Failing to report a CSI in that BWP.
(F) Do not send SRS in that BWP.
(G) DL-SCH is not received on that BWP.
(H) Clear all configured downlink assignments and/or all configured uplink grants of grant type 2 in that BWP.
(I) Suspend all configured uplink grants of grant type 1 for that Inactive BWP.

This section explains multiple transmit/receive point (also called multi-TRP or mTRP) operation.

In mTRP operation, the serving cell may be able to schedule terminal devices from multiple TRPs (Transmit/Receive Points) to provide better coverage, reliability, and/or data rates for PDSCH, PDCCH, PUSCH, and PUCCH.

There may be two different operation modes for scheduling PDSCH transmissions of mTRP. The two operation modes may be single-DCI and multi-DCI. The control of uplink and downlink operation for both modes may be performed at the PHY and MAC layers with configuration set by the RRC layer. In single-DCI mode, the terminal device may be scheduled for both TRPs by the same DCI. In multi-DCI mode, the terminal device may be scheduled for each TRP by an independent DCI.

Each TRP of the mTRP may be identified by TRP information. For example, the TRP information may be information for identifying one TRP among one or more TRPs. For example, the TRP information may be an index for identifying one TRP. For example, one TRP may be determined based on the TRP information. For example, the TRP information may be information for identifying one or more TRPs. The TRP information may be used to select one TRP. The TRP information may be a CORESET pool index. One CORESET may be associated with one CORESET pool index and one CORESET resource set identifier. The terminal device may transmit a PUSCH with a corresponding TRP based on the CORESET resource set identifier. The TRP information may be associated with an index of the CORESET resource pool. For example, a first CORESET pool index may be associated with a first TRP, and a second CORESET pool index may be associated with a second TRP. The TRP information may be associated with a pool (or a pool index) of a TCI state. For example, a first TCI state pool (or pool index) may be associated with a first TRP, and a second TCI state pool (or pool index) may be associated with a second TRP.

There may be two different operation modes for scheduling PDCCH transmissions of an mTRP. The two operation modes may be PDCCH repetition and single frequency network (SFN) based PDCCH transmission. In both modes, the terminal device can receive each of the PDCCH transmissions carrying the same DCI from each TRP. In the PDCCH repetition mode, the terminal device can receive two PDCCH transmissions carrying the same DCI from two linked search spaces, each associated with a different CORESET. In the SFN based PDCCH transmission mode, the terminal device can receive two PDCCH transmissions carrying the same DCI from a single search space/CORESET using different TCI states.

In mTRP PUSCH repetition, upon indication by a single DCI or a configured uplink grant provided by RRC signaling, the terminal device may perform PUSCH transmission of the same content in beam directions associated with different spatial relations corresponding to two TRPs.

In mTRP PUCCH repetition, the terminal device may perform PUCCH transmission of the same content in beam directions associated with different spatial relationships corresponding to two TRPs.

In inter-cell mTRP operation, one or more TCI states in a multi-DCI PDSCH transmission may be associated with an SSB of a Physical Cell Identity (PCI) different from the PCI of the serving cell. Also, at most one TCI state associated with a PCI different from the serving cell may be active at a time.

Next, we will explain the central unit (CU) and distributed unit (DU). The central unit may be a logical node that hosts the RRC layer, SDAP layer, and PDCP layer of the base station device. The distributed unit may be a logical node that hosts the RLC layer, MAC layer, and PHY layer of the base station device. The central unit may control the operation of one or more distributed units. One distributed unit may support one or more cells. One cell may be supported by only one distributed unit. Some of the functions of the central unit may be implemented in the distributed unit. Some of the functions of the distributed unit may be implemented in the central unit.

Next, we will explain Layer 1/Layer 2 triggered mobility (L1/L2-triggered mobility: LTM) in this embodiment.

Layer 1/Layer 2 triggered mobility may be a procedure in which a base station device transmits a DCI or MAC CE that causes a terminal device to identify one or more cells that are targets for the serving cell, and instructs the terminal device to switch (change) the serving cell or cells through the DCI or MAC CE. In addition or instead, Layer 1/Layer 2 triggered mobility may be a procedure in which a terminal device receives a DCI or MAC CE from a base station device that identifies one or more cells that are targets for the serving cell, and switches (changes) the serving cell to one or more cells indicated by the DCI or MAC CE.

For example, the DCI that allows the terminal device to identify one or more cells that are targets of the serving cell may be a DCI that includes one or more identifiers indicating one or more cells that are targets of the serving cell. Also, for example, the MAC CE that allows the terminal device to identify one or more cells that are targets of the serving cell may be a MAC CE that includes one or more identifiers indicating one or more cells that are targets of the serving cell. The identifiers may be identifiers that correspond to each of the information regarding one or more serving cell targets that is set in advance in the terminal device by, for example, RRC signaling. Also, the identifiers may be referred to as L1/L2 candidate target indexes.

In Layer 1/Layer 2 triggered mobility, the base station device may determine the serving cell target based on a measurement report provided from the terminal device. The measurement report may be a CSI report transmitted from the terminal device on a PUSCH. Additionally or alternatively, the measurement report may be a measurement report message transmitted from the terminal device as RRC signaling. Additionally or alternatively, the measurement report may be measurement report information transmitted from the terminal device as a MAC CE. The measurement report may also be other information.

Note that "Layer 1/Layer 2 triggered mobility" may be rephrased as "Layer 1/Layer 2 mobility (L1/L2 mobility)", "Layer 1/Layer 2 based inter-cell mobility (L1/L2 based inter-cell mobility)", "Layer 1/Layer 2 inter-cell mobility (L1/L2 inter-cell mobility)", "Layer 1/Layer 2 serving cell change processing", "Layer 1/Layer 2 serving cell change", or "Layer 1/Layer 2 handover", etc.

The term "L1/L2 candidate target identifier" may be rephrased as "candidate target index," "L1/L2 candidate configuration index," "candidate configuration index," "L1/L2 candidate target configuration identifier," or "candidate target configuration identifier," etc.

"DCI that causes the terminal device to identify one or more cells that are targets of the serving cell" may be rephrased as "DCI that instructs the terminal device to change the serving cell to one or more target cells" or "DCI that changes one or more serving cells of the terminal device", etc.

"A MAC CE that causes a terminal device to identify one or more cells that are targets of a serving cell" may be rephrased as "a MAC CE that instructs a change of the serving cell to one or more target cells" or "a MAC CE that changes one or more serving cells of a terminal device", etc.

DCI may also be referred to as Layer 1 signaling. MAC CE may also be referred to as Layer 2 signaling. The above-mentioned measurements may be performed by Layer 1 (PHY layer) and/or Layer 3 (RRC layer). The above-mentioned measurements may also be reported by Layer 1 (PHY layer), Layer 2 (MAC layer), and/or Layer 3 (RRC layer).

In Layer 1/Layer 2 triggered mobility, a base station device may notify a terminal device of information regarding a serving cell target. The information regarding the serving cell target may be notified to the terminal device by RRC signaling. Additionally or alternatively, the information regarding the serving cell target may be notified to the terminal device by MAC CE and/or DCI. For example, part of the information regarding the serving cell target may be notified to the terminal device in advance by RRC signaling, and when changing the serving cell to a target, another part of the information regarding the target may be notified to the terminal device by MAC CE and/or DCI. Information regarding the serving cell target is also referred to as the Layer 1/Layer 2 inter-cell mobility candidate target configuration, the L1/L2-triggered candidate target configuration, the L1/L2 candidate target configuration, or simply the candidate target configuration. In the following description, to avoid confusion with the conditional reconfiguration candidate target SpCell, etc., information regarding the serving cell target is referred to as the L1/L2 candidate target configuration. In addition, one or more L1/L2 candidate target configurations corresponding to one or more targets of the serving cell may be notified to the terminal device. The terminal device may store one or more L1/L2 candidate target configurations notified from the base station device.

In order to identify each of the one or more L1/L2 candidate target settings, for example, an L1/L2 candidate target identifier associated with each L1/L2 candidate target setting may be notified to the terminal device. The terminal device may store one or more L1/L2 candidate target settings notified from the base station device and the L1/L2 candidate target identifier associated with the L1/L2 candidate target setting.

In the Layer 1/Layer 2 trigger mobility, some or all of the mobility scenarios (A) to (C) below may be supported, or other mobility scenarios may be supported. In addition, in a terminal device in which CA is not configured, the mobility scenario (A) below may be a scenario in which only the PCell is changed, and in a terminal device in which CA is configured, the mobility scenario (A) below may be a scenario in which the PCell and one or more SCells are changed, or a scenario in which only the PCell is changed. In addition or instead, in a terminal device in which CA is configured, the mobility scenario (A) below may be a scenario in which the current PCell and SCell are replaced, that is, the target PCell and SCell become the current SCell and PCell, respectively.
(A) PCell change (B) Intra-DU mobility and intra-CU-inter-DU mobility (C) Inter-cell beam management

In Layer 1/Layer 2 triggered mobility, the following principles (A) and/or (B) may be applied.
(A) A base station device provides L1/L2 candidate target configuration so that dynamic switching can be performed without requiring full configuration.
(B) The user plane communicates continuously, preferably without resets, to avoid data loss and additional delays for data recovery.

In Layer 1/Layer 2 triggered mobility, some or all of the following (A) to (F) may be used for L1/L2 candidate target setting.
(A) Messages related to RRC connection reconfiguration (B) Cell group configuration (C) SpCell configuration and/or SCell configuration (D) Measurement configuration (E) Radio bearer configuration (F) Other information elements

The terminal device may be notified of one or more L1/L2 candidate target settings by RRC signaling or other signaling (MAC CE, DCI, etc.). The terminal device may store the L1/L2 candidate target settings until it receives a DCI or MAC CE instructing a change of the serving cell to one or more cells that are targets of the serving cell. The L1/L2 candidate target settings may be common between intra-distributed unit mobility and intra-aggregated unit inter-distributed unit mobility, or some of the L1/L2 candidate target settings may be different. The L1/L2 candidate target settings may include some or all of the system information (searchSpaceSIB1, searchSpaceOtherSystemInformation, etc.), paging messages (pagingSearchSpace, etc.), and common search spaces (commonSearchSpaceList, etc.). In addition, security key updates may not be performed in Layer 1/Layer 2 triggered mobility.

Each of the one or more cells configured in a given L1/L2 candidate target configuration is called a candidate cell or a candidate target cell.

The above cell group configuration, SpCell configuration, SCell configuration, measurement configuration, and bearer configuration may use the same information elements as those included in the message regarding the reconfiguration of the RRC connection, or may use information elements in which new parameters have been added and/or some or all of the parameters have been deleted from those included in the message regarding the reconfiguration of the RRC connection.

Each L1/L2 candidate target configuration may be a message regarding reconfiguration of an RRC connection. In this case, the L1/L2 candidate target configuration may include at least a cell group configuration related to the MCG. The cell group configuration may include at least an SpCell configuration. The cell group configuration may also include an SCell configuration. In addition, the L1/L2 candidate target configuration may include other information. For example, a cell group configuration related to the SCG may be included in the L1/L2 candidate target configuration. For example, a measurement configuration may be included in the L1/L2 candidate target configuration. For example, a radio bearer configuration may be included in the L1/L2 candidate target configuration. In addition to one or more L1/L2 candidate target configurations, an L1/L2 candidate target identifier for identifying each L1/L2 candidate target configuration may be notified from the base station device to the terminal device.

For example, the terminal device may receive DCI or MAC CE from the base station device that identifies one or more cells that are targets of the serving cell, and based on the L1/L2 candidate target identifier indicated by the DCI or MAC CE, apply a message regarding reconfiguration of the RRC connection, which is the L1/L2 candidate target setting corresponding to the L1/L2 candidate target identifier, to the RRC settings of the terminal device.

Each L1/L2 candidate target configuration may be a cell group configuration. In this case, the L1/L2 candidate target configuration may be a cell group configuration of an MCG. The cell group configuration may include at least an SpCell configuration. The cell group configuration may also include an SCell configuration. In addition, other information may be associated with the L1/L2 candidate target configuration. For example, a cell group configuration related to an SCG that is separately notified to a terminal device may be associated with the L1/L2 candidate target configuration. For example, a measurement configuration that is separately notified to a terminal device may be associated with the L1/L2 candidate target configuration. For example, a radio bearer configuration that is separately notified to a terminal device may be associated with the L1/L2 candidate target configuration. In addition to one or more L1/L2 candidate target configurations, an L1/L2 candidate target identifier for identifying each L1/L2 candidate target configuration may be notified from the base station device to the terminal device. In addition, when the L1/L2 candidate target setting is a cell group setting, the cell group of this L1/L2 candidate target setting may be referred to as a candidate cell group (CCG).

For example, the terminal device may receive DCI or MAC CE from the base station device, which identifies one or more cells that are targets of the serving cell, and apply a cell group setting, which is an L1/L2 candidate target setting corresponding to the L1/L2 candidate target identifier, to the MCG setting of the RRC of the terminal device based on the L1/L2 candidate target identifier indicated by the DCI or MAC CE. In addition, if there is information associated with the applied L1/L2 candidate target setting, the terminal device may apply the associated information to the RRC setting of the terminal device. Note that, for example, if the L1/L2 candidate target setting is set by a secondary node, this L1/L2 candidate target setting may be a cell group setting of the SCG. The terminal device may determine which cell group setting, MCG or SCG, to apply to the RRC setting of the terminal device based on which cell group the DCI or MAC CE identifying one or more cells that are targets of the serving cell is received from.

Furthermore, each of the L1/L2 candidate target settings notified to the terminal device may be a setting of a different structure. For example, one L1/L2 candidate target setting may be a cell group setting, and another L1/L2 candidate target setting may be an SpCell setting. In other words, the L1/L2 candidate target settings may have different structures depending on the choice (CHOICE) in the ASN.1 notation.

Furthermore, each of the L1/L2 candidate target settings notified to the terminal device may be referred to as a candidate target entry, and a list of one or more candidate target entries (candidate target entry list) may be notified to the terminal device.

Based on the above explanation, various embodiments of the present invention will be described. Note that the processes described above may be applied to the processes omitted in the following explanation.

FIG. 5 is a block diagram showing the configuration of a terminal device (UE122) in this embodiment. Note that, to avoid complicating the explanation, FIG. 5 shows only the main components closely related to this embodiment.

The UE 122 shown in FIG. 5 includes a receiver 500 that receives control information (DCI, RRC signaling, etc.) from a base station device, a processor 502 that performs processing according to parameters included in the received control information, and a transmitter 504 that transmits control information (UCI, RRC signaling, etc.) to the base station device. The base station device described above may be the eNB 102 or the gNB 108. The processor 502 may include some or all of the functions of various layers (e.g., the physical layer, the MAC layer, the RLC layer, the PDCP layer, the SDAP layer, the RRC layer, and the NAS layer). That is, the processor 502 may include some or all of the physical layer processor, the MAC layer processor, the RLC layer processor, the PDCP layer processor, the SDAP processor, the RRC layer processor, and the NAS layer processor.

FIG. 6 is a block diagram showing the configuration of a base station device in this embodiment. Note that, to avoid complicating the explanation, FIG. 6 shows only the main components closely related to this embodiment. The above-mentioned base station device may be eNB102 or gNB108.

The base station device shown in FIG. 6 includes a transmitter 600 that transmits control information (DCI, RRC signaling, etc.) to UE 122, a processor 602 that creates control information (DCI, RRC signaling including parameters, etc.) and transmits it to UE 122, causing the processor 502 of UE 122 to process it, and a receiver 604 that receives control information (UCI, RRC signaling, etc.) from UE 122. The processor 602 may include some or all of the functions of various layers (e.g., physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processor 602 may include some or all of the physical layer processor, MAC layer processor, RLC layer processor, PDCP layer processor, SDAP processor, RRC layer processor, and NAS layer processor.

An example of the processing of the terminal device (UE 122) in this embodiment will be described with reference to FIG. 9. Note that in this embodiment, the processing unit 502 of the UE 122 may include an RRC processing unit that performs RRC processing and a MAC processing unit that performs MAC processing.

FIG. 9 is a diagram showing an example of processing by the UE 122 in this embodiment. The processing unit 502 of the UE 122 judges the conditions (step S900) and operates based on the judgment (step S902).

UE122 receives RRC signaling from a base station device (gNB108 and/or eNB102). The RRC signaling may include one or more L1/L2 candidate target configurations. The RRC processing unit of UE122 may hold one or more L1/L2 candidate target configurations included in the RRC signaling. The RRC signaling may include an identifier (L1/L2 candidate target identifier) that identifies each of the one or more L1/L2 candidate target configurations. Note that in this embodiment, the L1/L2 candidate target configurations include at least one SCell configuration.

UE122 may receive, from a base station device (gNB108 and/or eNB102), a MAC CE (referred to as an LTM MAC CE in the following description, but may be a MAC CE with another name) that identifies one or more target cells of a serving cell of a certain cell group. In addition to or instead of this, UE122 may receive, from a base station device (gNB108 and/or eNB102), a MAC CE that includes information indicating that each SCell of a certain cell group is to be activated or information indicating that each SCell is to be deactivated in a serving cell of the certain cell group. In the following description, the MAC processing unit of UE122 may be the MAC processing unit of this cell group unless explicitly stated. In this embodiment, the LTM MAC CE identifies at least one target SCell.

The MAC processing unit of UE 122 that has received the LTM MAC CE and a MAC CE including information indicating that the SCell is to be activated or information indicating that the SCell is to be deactivated determines in step S900 whether each of the following conditions (a) to (c) is satisfied. In the following description, the SCell activated by the MAC CE including information indicating that the SCell is to be activated may be a part or all of the target SCells identified by the LTM MAC CE, and the SCell deactivated by the MAC CE including information indicating that the SCell is to be deactivated may be a part or all of the target SCells identified by the LTM MAC CE.
(a) Information indicating that the target SCell identified by the LTM MAC CE is to be activated (for example, sCellState set to activated) is set by a higher layer (such as RRC).
(b) The LTM MAC CE and a MAC CE including information indicating to activate the target SCell are included in the same MAC PDU, or the LTM MAC CE includes information indicating to UE 122 to activate the target SCell.
(c) The LTM MAC CE and a MAC CE including information indicating to deactivate the target SCell are included in the same MAC PDU, or the LTM MAC CE includes information indicating to UE 122 to deactivate the target SCell.

In step S902, the MAC processing unit of UE122 notifies the RRC processing unit of information indicating the target of the serving cell identified by the LTM MAC CE (e.g., L1/L2 candidate target identifier).

The RRC processing unit of UE122 performs a process (L1/L2 candidate target setting application process) of applying the L1/L2 candidate target setting selected based on information indicating the target of the serving cell identified by the LTM MAC CE to the RRC setting of the terminal device. In addition, after performing the L1/L2 candidate target setting application process, the RRC processing unit of UE122 notifies the MAC processing unit of information indicating that the L1/L2 candidate target setting application process has been completed.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (b) is satisfied, then in step S902, the MAC processing unit activates the target SCell based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process has been completed.In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (b) is satisfied, then in step S902, the MAC processing unit activates the target SCell based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process has been completed.

Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (b) is satisfied, then in step S902, the MAC processing unit of UE122 activates the target SCell based on the setting of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (b) is satisfied, then in step S902, the MAC processing unit of UE122 performs the above-mentioned process (AD-1) on the target SCell based on the setting of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. Note that "after receiving the LTM MAC CE" may be rephrased as "upon receiving the LTM MAC CE", "based on receiving the LTM MAC CE", "after notifying the RRC processing unit of information indicating the target serving cell identified by the LTM MAC CE", etc.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (c) is satisfied, then in step S902, the MAC processing unit deactivates the target SCell based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process has been completed.In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (c) is satisfied, then in step S902, the MAC processing unit performs the above-mentioned process (AD-2) and/or process (AD-3) on the target SCell based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process has been completed.

Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (c) is satisfied, then in step S902, the MAC processing unit deactivates the target SCell based on the setting of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (c) is satisfied, then in step S902, the MAC processing unit performs the above-mentioned process (AD-2) and/or process (AD-3) on the target SCell based on the setting of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. Note that "after receiving the LTM MAC CE" may be rephrased as "upon receiving the LTM MAC CE", "based on receiving the LTM MAC CE", "after notifying the RRC processing unit of information indicating the target serving cell identified by the LTM MAC CE", etc.

Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the conditions (b) and (c) are not satisfied and that the condition (a) is satisfied, then in step S902, the MAC processing unit activates the target SCell. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the conditions (b) and (c) are not satisfied and that the condition (a) is satisfied, then in step S902, the MAC processing unit performs the above-mentioned process (AD-1) on the target SCell. In this case, the MAC processing unit of UE122 may operate in step S902 without being notified by the RRC processing unit that the L1/L2 candidate target configuration application process has been completed. Additionally or alternatively, the MAC processing unit of UE122 may operate in step S902 without being based on configuring one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. In addition, "after receiving the LTM MAC CE" may be rephrased as "upon receiving the LTM MAC CE," "based on receiving the LTM MAC CE," or "after notifying the RRC processing unit of information indicating the target serving cell identified by the LTM MAC CE," etc.

Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, it deactivates the target SCell in step S902. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, it performs the above-mentioned process (AD-2) and/or process (AD-3) on the target SCell in step S902. In this case, the MAC processing unit of UE122 may operate in step S902 without being notified by the RRC processing unit that the L1/L2 candidate target configuration application process has been completed. Additionally or alternatively, the MAC processing unit of UE122 may operate in step S902 without being based on configuring one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. In addition, "after receiving the LTM MAC CE" may be rephrased as "upon receiving the LTM MAC CE," "based on receiving the LTM MAC CE," or "after notifying the RRC processing unit of information indicating the target serving cell identified by the LTM MAC CE," etc.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, then in step S902 it activates the target SCell based on the reception of a MAC CE including information indicating that the target SCell is to be activated. In addition or instead, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, then in step S902 it performs the above-mentioned process (AD-1) on the target SCell based on the reception of a MAC CE including information indicating that the target SCell is to be activated. In addition or instead, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, then in step S902 it deactivates the target SCell based on the reception of a MAC CE including information indicating that the target SCell is to be deactivated. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that none of the conditions (a) to (c) are satisfied, then in step S902, the MAC processing unit performs the above-mentioned process (AD-2) and/or process (AD-3) on the target SCell based on receiving a MAC CE including information indicating that the target SCell is to be deactivated. In this case, the MAC processing unit of UE122 may operate in step S902 without being notified by the RRC processing unit that the L1/L2 candidate target configuration application process has been completed. Additionally or alternatively, the MAC processing unit of UE122 may operate in step S902 without being based on configuring one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE. In addition, "after receiving the LTM MAC CE" may be rephrased as "upon receiving the LTM MAC CE," "based on receiving the LTM MAC CE," or "after notifying the RRC processing unit of information indicating the target serving cell identified by the LTM MAC CE," etc.

Next, an example of another process of the terminal device (UE122) in this embodiment will be described with reference to FIG. 9. Note that the processes described in this embodiment may be used in combination with each other.

In FIG. 9, the processing unit 502 of the UE 122 judges the conditions (step S900) and operates based on the judgment (step S902).

UE122 may receive from a base station device (gNB108 and/or eNB102) a MAC CE including information indicating that each SCell of a cell group is to be activated or information indicating that each SCell is to be deactivated in a serving cell of the cell group. In the following description, the MAC processing unit of UE122 may be the MAC processing unit of the cell group unless otherwise specified. In addition or instead, being identified by a MAC CE including information indicating that a SCell is to be activated may mean, for example, that information of a MAC CE corresponding to an identifier of the SCell indicates that the SCell is to be activated, and being identified by a MAC CE including information indicating that a SCell is to be deactivated may mean, for example, that information of a MAC CE corresponding to an identifier of the SCell indicates that the SCell is to be deactivated.

The MAC processing unit of UE 122 that has received a MAC CE including information indicating that the SCell is to be activated or information indicating that the SCell is to be deactivated determines, in step S900, whether each of the following conditions (d) and (e) is satisfied.
(d) An LTM MAC CE that specifies one or more of the SCells to be activated is included in a MAC PDU that includes a MAC CE including information indicating that the SCell is to be activated.
(e) An LTM MAC CE that specifies one or more SCells to be deactivated is included in a MAC PDU that includes a MAC CE that includes information indicating that the SCell is to be deactivated.

If the MAC processing unit of UE122 determines in step S900 that the condition (d) is satisfied, then in step S902, the MAC processing unit activates the LTM MAC CE and the SCell identified by the MAC CE including information indicating that the SCell is to be activated, based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process based on the LTM MAC CE described in the condition (d) has been completed. In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (d) is satisfied, then in step S902, the MAC processing unit performs the above-mentioned process (AD-1) on the SCell identified by the MAC CE including information indicating that the LTM MAC CE and the SCell are to be activated, based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process based on the LTM MAC CE described in the condition (d) has been completed.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (d) is satisfied, then in step S902, it activates the LTM MAC CE and the SCell identified by the MAC CE including information indicating that the SCell is to be activated based on the configuration of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE described in the condition (d).In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (d) is satisfied, then in step S902, it performs the above-mentioned process (AD-1) on the SCell identified by the MAC CE including information indicating that the LTM MAC CE and the SCell are to be activated based on the configuration of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE described in the condition (d). In addition, "after receiving the LTM MAC CE described in the condition (d)" may be rephrased as "upon receiving the LTM MAC CE described in the condition (d)", "based on receiving the LTM MAC CE described in the condition (d)", or "after notifying the RRC processing unit of information indicating the target of the serving cell identified by the LTM MAC CE described in the condition (d)", etc.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (e) is satisfied, then in step S902, based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process based on the LTM MAC CE described in the condition (e) has been completed, the MAC processing unit deactivates the LTM MAC CE and the SCell identified by the MAC CE including information indicating that the SCell is to be deactivated.In addition or instead, if the MAC processing unit of UE122 determines in step S900 that the condition (e) is satisfied, then in step S902, based on the notification from the RRC processing unit that the L1/L2 candidate target setting application process based on the LTM MAC CE described in the condition (e) has been completed, the MAC processing unit performs the above-mentioned process (AD-2) and/or process (AD-3) on the LTM MAC CE and the SCell identified by the MAC CE including information indicating that the SCell is to be deactivated.

Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (e) is satisfied, then in step S902, the MAC processing unit deactivates the LTM MAC CE and the SCell identified by the MAC CE including information indicating that the SCell is to be deactivated, based on the configuration of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE described in the condition (e). Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that the condition (e) is satisfied, then in step S902, the MAC processing unit of UE122 performs the above-mentioned processing (AD-2) and/or processing (AD-3) on the SCell identified by the MAC CE including information indicating that the LTM MAC CE and the SCell are to be deactivated, based on the configuration of one or more SCells identified by the LTE MAC CE after receiving the LTM MAC CE described in the condition (e). In addition, "after receiving the LTM MAC CE described in the condition (e)" may be rephrased as "upon receiving the LTM MAC CE described in the condition (e)", "based on receiving the LTM MAC CE described in the condition (e)", or "after notifying the RRC processing unit of information indicating the target of the serving cell identified by the LTM MAC CE described in the condition (e)", etc.

In addition or instead, if the MAC processing unit of UE122 determines in step S900 that neither of the conditions (d) nor (e) is satisfied, then in step S902, based on receiving a MAC CE including information indicating that the SCell is to be activated, the MAC processing unit of UE122 activates the SCell identified by the MAC CE including information indicating that the SCell is to be activated.In addition or instead, if the MAC processing unit of UE122 determines in step S900 that neither of the conditions (d) nor (e) is satisfied, then in step S902, based on receiving a MAC CE including information indicating that the SCell is to be activated, the MAC processing unit of UE122 performs the above-mentioned process (AD-1) on the SCell identified by the MAC CE including information indicating that the SCell is to be activated. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that neither of the conditions (d) nor (e) is satisfied, then in step S902, based on receiving a MAC CE including information indicating that the SCell is to be deactivated, the MAC processing unit of UE122 deactivates the SCell identified by the MAC CE including information indicating that the SCell is to be deactivated. Additionally or alternatively, if the MAC processing unit of UE122 determines in step S900 that neither of the conditions (d) nor (e) is satisfied, then in step S902, based on receiving a MAC CE including information indicating that the SCell is to be deactivated, the MAC processing unit of UE122 performs the above-mentioned processing (AD-2) and/or processing (AD-3) on the SCell identified by the MAC CE including information indicating that the SCell is to be deactivated.

The MAC CE including the information indicating to activate the above-mentioned SCell may be, for example, an SCell Activation/Deactivation MAC CE indicating to activate the SCell, or an Enhanced SCell Activation/Deactivation MAC CE indicating to activate the SCell, and the MAC CE including the information indicating to deactivate the above-mentioned SCell may be, for example, an SCell Activation/Deactivation MAC CE indicating to deactivate the SCell, or an Enhanced SCell Activation/Deactivation MAC CE indicating to deactivate the SCell. Additionally or alternatively, the MAC CE including the information indicating to activate the above-mentioned SCell and the MAC CE including the information indicating to deactivate the SCell may be the same MAC CE (for example, a MAC CE named SCell Activation/Deactivation MAC CE or Enhanced SCell Activation/Deactivation MAC CE indicating with one bit whether each SCell is to be activated or deactivated). Additionally or alternatively, the information in condition (b) indicating that UE122 should activate the SCell and the information in condition (c) indicating that UE122 should deactivate the SCell may be the same information (e.g., a MAC CE named SCell Activation/Deactivation MAC CE or Enhanced SCell Activation/Deactivation MAC CE, which indicates in one bit whether each SCell is to be activated or deactivated). Additionally or alternatively, in the L1/L2 candidate target setting application process, the MAC processing unit of UE122 may determine not to perform the above-mentioned process (AD) for each SCell identified by the LTM MAC CE.

This makes it possible to efficiently activate/deactivate the target SCell in Layer 1/Layer 2 triggered mobility.

In the above description, once a timer is started, it runs until it is stopped or expires. Once a timer expires, it may be considered to be not running (stopped). A timer is always started (if the timer is stopped) or restarted (if the timer is running) from its initial value. The period from when the timer is started or restarted to when it expires is not updated until the timer is stopped or expired. The MAC entity of the terminal device may use a value notified by a higher layer (e.g., the RRC layer) as the period from when the timer is started or restarted to when it expires. In addition or instead, the MAC entity of the terminal device may use a pre-configured default value as the period from when the timer is started or restarted to when it expires. If the MAC entity of the terminal device sets the period from when the timer is started or restarted to when it expires to 0, the timer may expire immediately after it is started, unless other conditions are specified.

Furthermore, unless otherwise specified, the radio bearer in the above description may be a DRB, an SRB, or a DRB and an SRB. In addition or instead, the radio bearer in the above description may be an MRB.

In addition, in the above description, expressions such as "user plane," "user plane protocol," and "user plane interface" may be used interchangeably.

In addition, in the above description, "receive a DCI or MAC control element instructing a change of serving cell to one or more target cells" may be rephrased as "be instructed to change the serving cell to one or more target cells."

In addition, in the above description, expressions such as "candidate target," "candidate cell," and "CCG" may be used interchangeably.

Furthermore, unless otherwise specified, the serving cell change in the above description may refer to a layer 1/layer 2 serving cell change.

In addition, in the above explanation, expressions such as "to be notified" and "to be pointed out" may be used interchangeably.

In addition, in the above description, expressions such as "link," "associate," and "relate" may be used interchangeably.

In addition, in the above description, expressions such as "includes," "included," and "was included" may be used interchangeably.

In addition, in the above explanation, "the above-mentioned" can be replaced with "the above-mentioned".

In addition, in the above explanation, expressions such as "determined to be...", "is set to...", "contains..." and the like may be used interchangeably.

Furthermore, in each of the process examples or process flow examples in the above description, some or all of the steps may not be executed. Furthermore, in each of the process examples or process flow examples in the above description, the order of the steps may be different. Furthermore, in each of the process examples or process flow examples in the above description, some or all of the processing within each step may not be executed. Furthermore, in each of the process examples or process flow examples in the above description, the order of the processing within each step may be different. Furthermore, in the above description, "doing B based on A being true" may be rephrased as "doing B". In other words, "doing B" may be executed independently of "A being true".

In addition, in the above explanation, "A may be replaced with B" may mean replacing A with B, as well as replacing B with A. Also, in the above explanation, when it is written that "C may be D" and "C may be E", it may also mean that "D may be E". Also, in the above explanation, when it is written that "F may be G" and "G may be H", it may also mean that "F may be H".

In addition, in the above explanation, if condition "A" and condition "B" are contradictory conditions, condition "B" may be expressed as the "other" condition of condition "A."

The program that runs on the device related to this embodiment may be a program that controls a Central Processing Unit (CPU) or the like to cause a computer to function so as to realize the functions of this embodiment. The program or the information handled by the program is temporarily loaded into volatile memory such as Random Access Memory (RAM) during processing, or stored in non-volatile memory such as flash memory or a Hard Disk Drive (HDD), and is read, modified, and written by the CPU as necessary.

It should be noted that a part of the device in the above-mentioned embodiment may be realized by a computer. In that case, a program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize the control function. The "computer system" referred to here is a computer system built into the device, and includes hardware such as an operating system and peripheral devices. Furthermore, the "computer-readable recording medium" may be any of semiconductor recording media, optical recording media, magnetic recording media, etc.

Furthermore, "computer-readable recording medium" may include something that dynamically holds a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or something that holds a program for a certain period of time, such as volatile memory within a computer system that serves as a server or client in such a case. The above program may also be one that realizes part of the functions described above, or one that can realize the functions described above in combination with a program already recorded in the computer system.

Furthermore, each functional block or feature of the device used in the above-mentioned embodiment may be implemented or executed by an electric circuit, typically an integrated circuit or a plurality of integrated circuits. The electric circuit designed to execute the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, or alternatively, the processor may be a conventional processor, controller, microcontroller, or state machine. The general-purpose processor or each of the aforementioned circuits may be composed of digital circuits or analog circuits. Furthermore, if an integrated circuit technology that replaces current integrated circuits emerges due to the progress of semiconductor technology, it is also possible to use an integrated circuit based on that technology.

Note that this embodiment is not limited to the above embodiment. In the embodiment, an example of a device is described, but this embodiment is not limited to this, and can be applied to terminal devices or communication devices such as stationary or non-movable electronic devices installed indoors or outdoors, for example, AV equipment, kitchen equipment, cleaning/washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

Although this embodiment has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of this embodiment are also included. Furthermore, this embodiment can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this embodiment. Also included are configurations in which elements described in the above embodiments are substituted for elements that have the same effect.

One aspect of the present invention can be used, for example, in a communication system, a communication device (e.g., a mobile phone device, a base station device, a wireless LAN device, or a sensor device), an integrated circuit (e.g., a communication chip), or a program, etc.

100 E-UTRA
102 eNB
104 EPC
106 NR
108 gNB
110 5GC
112, 114, 116, 118, 120, 124 Interface
122UE
200, 300 PHY
202, 302 MAC
204, 304 RLC
206, 306 PDCP
208, 308 RRC
310SDAP
210, 312 NAS
500, 604 Receiver
502, 602 Processing section
504, 600 Transmitter

Claims (3)

1. A terminal device that communicates with a base station device,
   A receiver that receives a first MAC CE indicating an identifier that identifies one or more candidate target configurations including a target SCell from the base station device;
   An RRC processing unit;
   A MAC processing unit;
   Equipped with
   The RRC processing unit:
   Based on the MAC processing unit receiving the first MAC CE,
   the candidate target configuration identified by the first MAC CE,
   Applying to the RRC setting of the terminal device,
   The MAC processing unit,
   determining whether the applied candidate target configuration includes information indicating that the target SCell is to be activated;
   Based on the above judgment,
   Activating or deactivating the target SCell;
   Terminal device.
2. A method for a terminal device communicating with a base station device, comprising:
   a MAC entity of the terminal device,
   receiving a first MAC CE indicating an identifier identifying one or more candidate target configurations including a target SCell from the base station device;
   An RRC entity of the terminal device,
   Based on the MAC entity receiving the first MAC CE,
   the candidate target configuration identified by the first MAC CE,
   Applying the RRC setting of the terminal device;
   said MAC entity:
   determining whether the applied candidate target configuration includes information indicating to activate the target SCell;
   Based on the above judgment,
   activating or deactivating the target SCell;
   The method includes:
3. An integrated circuit implemented in a terminal device that communicates with a base station device,
   a MAC entity of the terminal device,
   receiving a first MAC CE indicating an identifier for identifying one or more candidate target configurations including a target SCell from the base station device;
   An RRC entity of the terminal device,
   Based on the MAC entity receiving the first MAC CE,
   the candidate target configuration identified by the first MAC CE,
   A function to be applied to the RRC setting of the terminal device;
   said MAC entity:
   a function of determining whether the applied candidate target configuration includes information indicating that the target SCell is to be activated;
   Based on the above judgment,
   A function for activating or deactivating the target SCell;
   An integrated circuit that exerts

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