Terminal device, method, and integrated circuit

Abstract

A processing unit of this terminal device applies, on the basis of the value of a first timing advance command and a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of one or more LTM candidate cell configurations, the value of the timing advance of a SpCell among one or more LTM candidate cells associated with the first LTM candidate cell configuration.

Description

Terminal device, method, and integrated circuit

[0001] The present invention relates to a terminal device, a method, and an integrated circuit.This application claims priority to Japanese Patent Application No. 2023-148027, filed on September 13, 2023, the contents of which are incorporated herein by reference.

[0002] 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 radio access, core networks, services, etc.

[0003] For example, 3GPP has begun technical studies and standardization of E-UTRA (Evolved Universal Terrestrial Radio Access) as a radio access technology (RAT) for 3.9G and 4G cellular mobile communication systems. 3GPP is currently conducting technical studies and standardization of E-UTRA extension technologies. E-UTRA is also called Long Term Evolution (LTE: registered trademark), and the extension technologies are sometimes called LTE-Advanced (LTE-A) and LTE-Advanced Pro (LTE-A Pro).

[0004] Additionally, 3GPP has begun technical studies and standardization of NR (New Radio, or NR Radio access) as a radio access technology (RAT) for 5th Generation (5G) cellular mobile communication systems. 3GPP is currently conducting technical studies and standardization of NR extension technologies.

[0005] 3GPP TS 38.300 v16.4.0,"NR;NR and NG-RAN Overall description; Stage 2" pp10-1343GPP TS 36.300 v16.4.0,"Evolved Universal Terrestrial Radio Access (E-UTRA)and Evolved Universal Terrestrial Radio Access Network (E-UTRAN);Overall description; Stage 2" pp19-3623GPP TS 38.331 v16.3.1,"NR;Radio Resource Control (RRC);Protocol specifications"pp21-8813GPP TS 36.331 v16.3.0,"Evolved Universal Terrestrial Radio Access (E-UTRA);Radio Resource Control (RRC);Protocol specifications" pp25-10153GPP TS 37.340 v16.4.0,"EvolvedUniversal Terrestrial Radio Access (E-UTRA)and NR; Multi-Connectivity; Stage 2" pp7-773GPP TS 38.321 v16.3.0, "NR;Medium Access Control (MAC) protocol specification" pp8-1523GPP TS 38.331 v17.2.0, "NR;Radio Resource Control (RRC) protocol specification"3GPP TS 38.321 v17.2.0, "NR;Medium Access Control (MAC) protocol specification"

[0006] An extension of NR is the serving cell change technology, which 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 known as RRC) measurements, and the 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. Therefore, studies 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) have begun.

[0007] The details of the terminal device procedures in the 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 the Layer 1 / Layer 2 mobility optimization technology.

[0008] One aspect of the present invention has been made in consideration of the above-mentioned circumstances, and one of its objects is to provide a terminal device, a base station device, a communication method, and an integrated circuit that can efficiently perform communication control.

[0009] In order to achieve the above object, one aspect of the present invention provides the following means: That is, one aspect of the present invention provides a terminal device that communicates with a base station device using a serving cell, the terminal device comprising: an RRC receiver that receives RRC signaling including an LTM candidate target configuration from the base station device; an RRC processor that stores the LTM candidate target configuration in a terminal variable; a MAC receiver that receives a MAC CE from the base station device; and a MAC processor, wherein the LTM candidate target configuration includes at least one LTM candidate cell configuration, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, and the MAC CE includes a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, the first field being a timing advance command field that indicates whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid or not, and the MAC processorBased on the reception of CE, the RRC processing unit is notified of the trigger of an LTM cell switching process and the first LTM candidate target identifier, and the MAC processing unit determines that it is necessary to trigger a random access procedure for the LTM cell switching process based on the value indicated in the first field being set to a first value, applies the latest N_TA value of the TAG of the serving cell as the value of N_TA of the SpCell based on the value indicated in the first field being set to a second value different from the first value, and Based on the fact that the value indicated in the first field is set to a value other than the first value or the second value, the RRC processing unit sets a value of N_TA using the value of the first field and applies the value of N_TA as a value of the timing advance of the SpCell, and the RRC processing unit triggers an LTM cell switching process based on the information notified from the MAC processing unit, selects the first LTM candidate cell configuration from the one or more LTM candidate cell configurations, starts an RRC reconfiguration procedure in the LTM cell switching process, and applies the selected first LTM candidate cell configuration according to the RRC reconfiguration procedure.

[0010] Another aspect of the present invention is a method for a terminal device communicating with a base station device using a serving cell, the method comprising the steps of receiving RRC signaling including an LTM candidate target configuration from the base station device, storing the LTM candidate target configuration in a terminal variable, and receiving a MAC CE from the base station device, wherein the LTM candidate target configuration includes at least one or more LTM candidate cell configurations, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, the MAC CE including a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, the first field being a timing advance command field indicating whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid or not, and the method of the terminal device comprises the steps of: receiving RRC signaling including an LTM candidate target configuration from the base station device; storing the LTM candidate target configuration in a terminal variable; and receiving a MAC CE from the base station device,a step of notifying the RRC layer of the terminal device of a trigger for an LTM cell switching process and the first LTM candidate target identifier based on receiving a CE; a step of determining that a random access procedure for the LTM cell switching process needs to be triggered based on the value indicated in the first field being set to a first value; a step of applying the latest N_TA value of the TAG of the serving cell as the N_TA value of the SpCell based on the value indicated in the first field being set to a second value different from the first value; setting a value of N_TA using the value of the first field based on the value being set to a value other than the first value or the second value, and applying the value of N_TA as the timing advance value of the SpCell; triggering an LTM cell switching process based on information notified from the MAC layer of the terminal device; selecting the first LTM candidate cell configuration from the one or more LTM candidate cell configurations; initiating an RRC reconfiguration procedure in the LTM cell switching process; and applying the selected first LTM candidate cell configuration according to the RRC reconfiguration procedure.

[0011] Another aspect of the present invention is an integrated circuit implemented in a terminal device that communicates with a base station device using a serving cell, the integrated circuit including: a function for receiving RRC signaling including an LTM candidate target configuration from the base station device; a function for storing the LTM candidate target configuration in a terminal variable; and a function for receiving a MAC CE from the base station device, wherein the LTM candidate target configuration includes at least one or more LTM candidate cell configurations, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, and the MAC CE includes a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, the first field being a timing advance command field that indicates whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid or not, and the integrated circuit is configured to receive the MAC CE from the base station device.a function to notify an RRC layer of the terminal device of a trigger for an LTM cell switching process and the first LTM candidate target identifier based on receiving a CE; a function to determine that a random access procedure for the LTM cell switching process needs to be triggered based on the value indicated in the first field being set to a first value; a function to apply the latest N_TA value of the TAG of the serving cell as the N_TA value of the SpCell based on the value indicated in the first field being set to a second value different from the first value; the function of setting the value of N_TA using the value of the first field based on the value being set to a value other than the first value or the second value, and applying the value of N_TA as the timing advance value of the SpCell; the function of triggering an LTM cell switching process based on information notified from the MAC layer of the terminal device; the function of selecting the first LTM candidate cell configuration from the one or more LTM candidate cell configurations; the function of initiating an RRC reconfiguration procedure in the LTM cell switching process; and the function of applying the selected first LTM candidate cell configuration in accordance with the RRC reconfiguration procedure.

[0012] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0013] According to one aspect of the present invention, a terminal device, a method, and an integrated circuit can realize efficient communication control processing.

[0014] 1 is a schematic diagram of a communication system according to the present embodiment. 2 is a diagram of an example of an E-UTRA protocol configuration according to the present embodiment. 3 is a diagram of an example of an NR protocol configuration according to the present embodiment. 4 is a diagram showing an example of a procedure flow for various settings in RRC according to the present embodiment. 5 is a block diagram showing the configuration of a terminal device according to the present embodiment. 6 is a block diagram showing the configuration of a base station device according to the present embodiment. 7 is an example of an ASN.1 description included in a message related to reconfiguration of an RRC connection in NR according to the present embodiment. 8 is an example of an ASN.1 description representing a field and / or information element related to a ServingCellConfigCommon information element according to the present embodiment. 9 is an example of processing by a terminal device according to the present embodiment.

[0015] Hereinafter, this embodiment will be described in detail with reference to the drawings.

[0016] LTE (and LTE-A, LTE-A Pro) and NR may be defined as different radio access technologies (RATs). NR may also be defined as a technology included in LTE. LTE may also be defined as a technology included in NR. LTE that can connect 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 in 3GPP Release 15 or later. 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 also be applied to other technologies using other terminology. 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.

[0017] In this embodiment, the names of the nodes and entities and the processes performed by the nodes and entities are described when the radio access technology is E-UTRA or NR, but this embodiment may be used for other radio access technologies. The names of the nodes and entities in this embodiment may be different names.

[0018] 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.

[0019] 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 configured from 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 configured by eNBs may be referred to as E-UTRAN.

[0020] The EPC (Evolved Packet Core) 104 may be a core network. The interface 112 is an interface between the eNB 102 and the EPC 104 and may be referred to as an S1 interface. The 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 the interface 112 may terminate at a Mobility Management Entity (MME: not shown) in the EPC 104. The user plane interface of the interface 112 may terminate at a Serving Gateway (S-GW: not shown) in the EPC 104. The control plane interface of the interface 112 may be referred to as an S1-MME interface. The user plane interface of the interface 112 may be referred to as an S1-U interface.

[0021] Note that one or more eNBs 102 may be connected to the EPC 104 via an interface 112. An interface (not shown) may exist between the multiple eNBs 102 connected to the EPC 104. The interface between the multiple eNBs 102 connected to the EPC 104 may be referred to as an X2 interface.

[0022] The NR 106 may be a radio access technology. The NR 106 may also be an air interface between the UE 122 and the gNB 108. The air interface between the UE 122 and the gNB 108 may be referred to as a Uu interface. The gNB (g Node B) 108 may be a base station device. The gNB 108 may have the NR protocol described below. The NR protocol may be composed of an NR user plane (User Plane: UP) protocol described below and an NR control plane (Control Plane: CP) protocol described below. The gNB 108 may terminate the NR user plane (User Plane: UP) protocol and the NR control plane (Control Plane: CP) protocol for the UE 122.

[0023] 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 in an Access and Mobility Management Function (AMF: not shown) in 5GC110. The user plane interface of interface 116 may terminate in 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.

[0024] Note that one or more gNBs 108 may be connected to 5GC 110 via interface 116. An interface (not shown) may exist between multiple gNBs 108 connected to 5GC 110. The interface between multiple gNBs 108 connected to 5GC 110 may be referred to as an Xn interface.

[0025] The eNB 102 may have the capability to connect to the 5GC 110. The eNB 102 with the capability to connect to the 5GC 110 may be referred to as an ng-eNB. The interface 114 is an interface between the eNB 102 and the 5GC 110 and may be referred to as an NG interface. The 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 the interface 114 may terminate in the AMF in the 5GC 110. The user plane interface of the interface 114 may terminate in the UPF in the 5GC 110. The control plane interface of the interface 114 may be referred to as an NG-C interface. The user plane interface of the interface 114 may be referred to as an NG-U interface. A radio access network consisting of an ng-eNB or a gNB may be referred to as an NG-RAN. The NG-RAN, E-UTRAN, etc. may simply be referred to as a network. Furthermore, the network may include an eNB, ng-eNB, gNB, etc.

[0026] Note that one or more eNBs 102 may be connected to 5GC 110 via interface 114. An interface may exist between multiple eNBs 102 connected to 5GC 110 (not shown). The interface between multiple eNBs 102 connected to 5GC 110 may be referred to as an Xn interface. Furthermore, an eNB 102 connected to 5GC 110 and a gNB 108 connected to 5GC 110 may be connected by interface 120. The interface 120 between an eNB 102 connected to 5GC 110 and a gNB 108 connected to 5GC 110 may be referred to as an Xn interface.

[0027] The gNB 108 may have the function of connecting to the EPC 104. A gNB 108 with the function of connecting to the EPC 104 may be referred to as an en-gNB. Interface 118 is an interface between the gNB 108 and the EPC 104 and may be referred to as an S1 interface. A user plane interface through which user data passes may exist in interface 118. The user plane interface of interface 118 may terminate in an S-GW (not shown) in the EPC 104. The user plane interface of interface 118 may be referred to as an S1-U interface. Furthermore, the eNB 102 connecting to the EPC 104 and the gNB 108 connecting to the EPC 104 may be connected by interface 120. The interface 120 between the eNB 102 connecting to the EPC 104 and the gNB 108 connecting to the EPC 104 may be referred to as an X2 interface.

[0028] The interface 124 is an interface between the EPC 104 and the 5GC 110, and may be an interface that passes only the CP, only the UP, or both the CP and the UP. In addition, some or all of the interfaces such as the interface 114, the interface 116, the interface 118, the interface 120, and the interface 124 may not exist depending on the communication system provided by the communication carrier or the like.

[0029] The UE 122 may be a terminal device capable of receiving system information and paging messages transmitted from the eNB 102 and / or the gNB 108. The UE 122 may also be a terminal device capable of wireless connection with the eNB 102 and / or the gNB 108. The UE 122 may also be a terminal device capable of simultaneously establishing a wireless connection with the eNB 102 and a wireless connection with the gNB 108. The UE 122 may have an E-UTRA protocol and / or an NR protocol. The wireless connection may be a Radio Resource Control (RRC) connection.

[0030] Furthermore, the UE 122 may be a terminal device capable of connecting to the EPC 104 and / or the 5GC 110 via the eNB 102 and / or the gNB 108. When the core network to which the eNB 102 and / or the gNB 108, with which the UE 122 communicates, is connected is the EPC 104, each Data Radio Bearer (DRB) (described later) established between the UE 122 and the eNB 102 and / or the gNB 108 may be uniquely associated with each EPS (Evolved Packet System) bearer passing through the EPC 104. 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 frames passing through the same EPS bearer.

[0031] Furthermore, if the core network to which the eNB102 and / or gNB108 with which the UE122 communicates is connected is the 5GC110, each DRB established between the UE122 and the eNB102 and / or gNB108 may be further linked to one of the PDU (Packet Data Unit) sessions established within the 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). Each QoS flow may be identified by a QoS flow identifier (Identity, or ID). The same QoS may be guaranteed for data such as IP packets and Ethernet frames passing through the same QoS flow.

[0032] There may be no PDU sessions and / or QoS flows in the EPC 104. There may also be no EPS bearers in the 5GC 110. When the UE 122 is connected to the EPC 104, the UE 122 has information about the EPS bearers, but may not have information about the PDU sessions and / or QoS flows. When the UE 122 is connected to the 5GC 110, the UE 122 has information about the PDU sessions and / or QoS flows, but may not have information about the EPS bearers.

[0033] In the following description, the eNB102 and / or the gNB108 will also be simply referred to as a base station device, and the UE122 will also be simply referred to as a terminal device or a UE.

[0034] 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, an uplink (UL) may be a link from a terminal device to a base station device. Also, in this embodiment, a downlink (DL) may be a link from a base station device to a terminal device.

[0035] 2A is a diagram of an E-UTRA user plane (UP) protocol stack. As shown in FIG. 2A, 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 FIG. 2A, the E-UTRA user plane protocol stack may be composed of a PHY (Physical layer) 200, which is a radio physical layer, a MAC (Medium Access Control) 202, which is a medium access control layer, a RLC (Radio Link Control) 204, which is a radio link control layer, and a PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer.

[0036] FIG. 3A is a diagram of an NR user plane (UP) protocol stack. As shown in FIG. 3A, 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 FIG. 3A, the NR user plane protocol stack may be composed of a radio physical layer, PHY 300, a medium access control layer, MAC 302, a radio link control layer, RLC 304, a packet data convergence protocol layer, PDCP 306, and a service data adaptation protocol layer, SDAP (Service Data Adaptation Protocol) 310.

[0037] 2(B) is a diagram of the E-UTRA control plane (CP) protocol configuration. As shown in FIG. 2(B), in the E-UTRA CP protocol, RRC (Radio Resource Control) 208, which is a radio resource control layer, may be a protocol between the UE 122 and the eNB 102. That is, RRC 208 may be a protocol that terminates at the eNB 102 on the network side. Also, in the E-UTRA CP protocol, NAS (Non Access Stratum) 210, which is a non-AS (Access Stratum) layer, may be a protocol between the UE 122 and the MME. That is, NAS 210 may be a protocol that terminates at the MME on the network side.

[0038] 3(B) is a diagram of the NR control plane (CP) protocol configuration. As shown in FIG. 3(B), in the NR CP protocol, the radio resource control layer RRC 308 may be a protocol between the UE 122 and the gNB 108. That is, the RRC 308 may be a protocol that terminates at the gNB 108 on the network side. Also, in the NR CP protocol, the non-AS layer NAS 312 may be a protocol between the UE 122 and the AMF. That is, the NAS 312 may be a protocol that terminates at the AMF on the network side.

[0039] The AS (Access Stratum) layer may be a layer that terminates between the UE 122 and the eNB 102 and / or the gNB 108. That is, 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.

[0040] In this embodiment, hereinafter, there may be no distinction between the E-UTRA protocol and the NR protocol, and the terms PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) may be used. In this case, the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) may be 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, respectively, 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. Furthermore, the SDAP (SDAP layer) may be the SDAP (SDAP layer) of the NR protocol.

[0041] In this embodiment, when distinguishing between E-UTRA protocols and NR protocols, the PHY 200, MAC 202, RLC 204, PDCP 206, and RRC 208 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. The PHY 200, MAC 202, RLC 204, PDCP 206, and RRC 208 may also 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. Furthermore, when distinguishing between E-UTRA protocols and NR protocols, PHY 300, MAC 302, RLC 304, PDCP 306, and RRC 308 may be referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively. Furthermore, PHY 300, MAC 302, RLC 304, PDCP 306, and RRC 308 may be referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

[0042] This section 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 referred to as a MAC entity. An entity having some or all of the functions of the RLC layer may be referred to as an RLC entity. An entity having some or all of the functions of the PDCP layer may be referred to as a PDCP entity. An entity having some or all of the functions of the SDAP layer may be referred to as an SDAP entity. An entity having some or all of the functions of the RRC layer may be referred to as 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.

[0043] Note that 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. Also, 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. Also, segmented RLC SDUs may be referred to as RLC SDU segments.

[0044] Here, the base station apparatus and the terminal apparatus exchange (transmit and receive) signals in a higher layer. For example, the base station apparatus and the terminal apparatus may transmit and receive RRC messages (also referred to as RRC messages, RRC information, or RRC signaling) in the Radio Resource Control (RRC) layer. The base station apparatus and the terminal apparatus may also transmit and receive MAC control elements in the Medium Access Control (MAC) layer. The RRC layer of the terminal apparatus acquires system information broadcast from the base station apparatus. Here, the RRC messages, system information, and / or MAC control elements are also referred to as higher layer signals (higher layer signals) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by the terminal apparatus may be referred to as a higher layer parameter. In PHY layer processing, the higher layer refers to a layer higher than the PHY layer, and may therefore refer to 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 of the terminal device (mainly the RRC layer or MAC layer, etc.) 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, "being provided with upper layer parameters" may mean receiving an upper layer signal from the base station device, and providing the upper layer parameters included in the received upper layer signal 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 also include setting default parameters that are pre-assigned to the upper layer of the terminal device. When describing transmission of an RRC message from a terminal device to a base station device, the expression "submitting a message from an 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 an RRC entity may mean submitting a message to a PDCP layer. In a terminal device, "submitting a message to a lower layer" from an 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 a PHY layer, a MAC layer, an RLC layer, a PDCP layer, etc.

[0045] An example of the functions of the PHY will be described. The PHY of the terminal device may have a function to receive 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 to transmit data to the PHY of the base station device via an uplink (UL) physical channel. The PHY may be connected to a higher 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, an RNTI (Radio Network Temporary Identifier) ​​may be used to identify various control information.

[0046] Here, the physical channels will be described. The physical channels used for wireless communication between a terminal device and a base station device may include the following physical channels.

[0047] 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)

[0048] The PBCH may be used to broadcast system information required by a terminal device.

[0049] In addition, in NR, the PBCH may be used to broadcast a time index (SSB-Index) within a synchronization signal block (SSB) period.

[0050] 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 also be referred to as DCI formats) may be defined for transmitting the downlink control information. That is, a field for the downlink control information may be defined as 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 a serving cell. Monitoring the set of PDCCH candidates may mean attempting to decode the PDCCH according to a certain DCI format. Furthermore, 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 an RRC message (described later), and the like.

[0051] 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) used to indicate the state of a downlink channel. The uplink control information may also include a scheduling request (SR) used to request an uplink shared channel (UL-SCH) resource. The uplink control information may also include a hybrid automatic repeat reQuest ACKnowledgement (HARQ-ACK).

[0052] The PDSCH may be used to transmit downlink data (DL-SCH: Downlink Shared CHannel) from the MAC layer, and may also be used to transmit system information (SI) and random access responses (RAR) in the downlink.

[0053] 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 apparatus may be signaling common to multiple terminal apparatuses in a cell. The RRC signaling transmitted from the base station apparatus may also be signaling dedicated to a certain terminal apparatus (also referred to as dedicated signaling). That is, terminal apparatus-specific (UE-specific) information may be transmitted using signaling dedicated to a certain terminal apparatus. The PUSCH may also be used to transmit UE capabilities in the uplink.

[0054] The PRACH may be used to transmit a random access preamble and may be used to indicate initial connection establishment procedures, handover procedures, connection re-establishment procedures, synchronization (timing adjustment) for uplink transmissions, and requests for UL-SCH resources.

[0055] An example of the MAC function will be described. MAC may be called a MAC sublayer. MAC may have the function of mapping various logical channels to corresponding transport channels. Logical channels may be identified by logical channel identities (or logical channel IDs). MAC may be connected to the higher-level RLC via logical channels. Depending on the type of information to be transmitted, logical channels may be divided into control channels that transmit control information and traffic channels that transmit user information. Logical channels may also be divided into uplink logical channels and downlink logical channels. MAC may have the function of multiplexing MAC SDUs belonging to one or more different logical channels and providing them to the PHY. MAC may also have the function of demultiplexing MAC PDUs provided by the PHY and providing them to the higher layer via the logical channels to which each MAC SDU belongs. MAC may also have the function of performing error correction through HARQ (Hybrid Automatic Repeat reQuest). The MAC may also have the function of reporting scheduling information. The MAC may also have the function of prioritizing processing between terminal devices using dynamic scheduling. The MAC may also have the function of prioritizing processing between logical channels within one terminal device. The MAC may also have the function of prioritizing processing of overlapping resources within one terminal device. The E-UTRA MAC may have the function of identifying Multimedia Broadcast Multicast Services (MBMS). The NR MAC may also have the function of identifying Multicast / Broadcast Services (MBS). The MAC may have the function of selecting a transport format.The MAC may have functions such as discontinuous reception (DRX) and / or discontinuous transmission (DTX), a random access (RA) procedure, a power headroom report (PHR) function that notifies information about available transmission power, and a buffer status report (BSR) function that notifies information about the amount of data in the transmission buffer. The NR MAC may have a bandwidth adaptation (BA) function. The MAC PDU format used in the E-UTRA MAC may differ from that used in the NR MAC. The MAC PDU may also include a MAC control element (MAC CE), which is an element for controlling the MAC.

[0056] This section describes logical channels for uplink (UL) and / or downlink (DL) used in E-UTRA and / or NR.

[0057] The BCCH (Broadcast Control Channel) may be a downlink logical channel for broadcasting control information such as system information (SI).

[0058] A PCCH (Paging Control Channel) may be a downlink logical channel for carrying paging messages.

[0059] A CCCH (Common Control Channel) 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.

[0060] A DCCH (Dedicated Control Channel) may be a logical channel for transmitting dedicated control information bidirectionally, point-to-point, between a terminal device and a base station device. The dedicated control information may be control information dedicated to each terminal device. The DCCH may be used when the terminal device has an RRC connection.

[0061] A 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. A DTCH may be a logical channel for transmitting dedicated user data. Dedicated user data may be user data dedicated to each terminal device. A DTCH may exist in both uplink and downlink.

[0062] This section describes the mapping of logical channels and transport channels for the uplink in E-UTRA and / or NR.

[0063] The CCCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0064] The DCCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0065] The DTCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0066] This section describes the mapping of logical channels and transport channels for the downlink in E-UTRA and / or NR.

[0067] The BCCH may be mapped to a downlink transport channel, a BCH (Broadcast Channel) and / or a DL-SCH (Downlink Shared Channel).

[0068] The PCCH may be mapped to a PCH (Paging Channel), which is a downlink transport channel.

[0069] The CCCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0070] The DCCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0071] The DTCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0072] An example of the RLC function will be described. The RLC may be called an RLC sublayer. The E-UTRA RLC may have the function of segmenting and / or concatenating data provided by the PDCP in the upper layer and providing it to the lower layer. The E-UTRA RLC may have the function of reassembling and reordering data provided by the lower layer and providing it to the upper layer. The NR RLC may have the function of adding a sequence number independent of the sequence number added by PDCP to data provided by the PDCP in the upper layer. The NR RLC may also have the function of segmenting data provided by PDCP and providing it to the lower layer. The NR RLC may also have the function of reassembling data provided by the lower layer and providing it to the upper layer. The RLC may also have the function of data retransmission and / or retransmission request (Automatic Repeat reQuest: ARQ). RLC may also have a function for performing error correction using ARQ. The control information sent from the receiving side of RLC to the transmitting side to indicate data that needs to be retransmitted in order to perform ARQ 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 a function for detecting data duplication. RLC may also have a function for discarding data. RLC may have three modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). In TM, data received from an upper layer is not segmented, and an RLC header need not be added. The TM RLC entity is a unidirectional entity, and the terminal device may configure the TM RLC entity as either a transmitting TM RLC entity or a receiving TM RLC entity.In UM, the RLC entity performs segmentation and / or concatenation of data received from a higher layer, addition of an RLC header, etc., but does not need to perform data retransmission control. The UM RLC entity may be a unidirectional entity or a bidirectional entity. If the UM RLC entity is a unidirectional entity, the terminal device may configure the UM RLC entity as a transmitting UM RLC entity or a receiving UM RLC entity. If the UM RLC entity is a bidirectional entity, the terminal device may configure the UM RLC entity as a UM RLC entity consisting of a transmitting side and a receiving side. In AM, the RLC entity may perform segmentation and / or concatenation of data received from a higher layer, addition of an RLC header, data retransmission control, etc. The AM RLC entity is a bidirectional entity, and the terminal device may configure the AM RLC entity 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 referred to as a 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 UM 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 differ from the RLC PDU format used in NR RLC. Furthermore, RLC PDUs may include data RLC PDUs and control RLC PDUs. Data RLC PDUs may be referred to as RLC DATA PDUs (RLC Data PDUs). Control RLC PDUs may be referred to as RLC CONTROL PDUs (RLC Control PDUs).

[0073] An example of PDCP functionality will be described. 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 interfaces. 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 / 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 a function for discarding duplicately received data. 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 that used in NR PDCP. PDCP PDUs may include data PDCP PDUs and control PDCP PDUs. The data PDCP PDU may be called a PDCP DATA PDU (PDCP Data PDU). The control PDCP PDU may be called a PDCP CONTROL PDU (PDCP Control PDU).

[0074] An example of the SDAP function will be described. The SDAP is a service data adaptation protocol layer. The SDAP may have the function of mapping a downlink QoS flow sent from the 5GC 110 to the terminal device via the base station device to a data radio bearer (DRB), and / or mapping an uplink QoS flow sent from the terminal device to the 5GC 110 via the base station device to a DRB. The SDAP may also have the function of storing mapping rule information. The SDAP may also have the function of marking a QoS flow identifier (QoS Flow ID: QFI). The SDAP PDU may include a data SDAP PDU and a control SDAP PDU. The data SDAP PDU may be called an SDAP DATA PDU (SDAP Data PDU). The control SDAP PDU may be called an SDAP CONTROL PDU (SDAP Control PDU). One SDAP entity in the terminal device may exist for each PDU session.

[0075] An example of the functions of the RRC will be described. The RRC may have a broadcast function. The RRC may have a paging function from the EPC 104 and / or the 5GC 110. The RRC may have a paging function from the eNB 102 connected to the gNB 108 or the 5GC 110. The RRC may also have an RRC connection management function. The RRC may also have a radio bearer control function. The RRC may also have a cell group control function. The RRC may also have a mobility control function. The RRC may also have terminal device measurement reporting and terminal device measurement reporting control functions. The RRC may also have a QoS management function. The RRC may also have a radio link failure detection and recovery function. The RRC may use RRC messages to perform broadcasting, paging, RRC connection management, radio bearer control, cell group control, mobility control, terminal device measurement reporting and terminal device measurement reporting control, QoS management, radio link failure detection and recovery, 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.

[0076] RRC messages may be sent using the logical channel BCCH, the logical channel PCCH, the logical channel CCCH, or the logical channel DCCH, and RRC messages sent using the DCCH may be referred to as dedicated RRC signaling or RRC signaling.

[0077] The RRC messages sent using the BCCH may include, for example, a Master Information Block (MIB), various types of System Information Blocks (SIBs), or other RRC messages.The RRC messages sent using the PCCH may include, for example, paging messages or other RRC messages.

[0078] RRC messages transmitted 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. Also, 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. Other RRC messages may also be included.

[0079] The RRC message transmitted 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 reject message (RRC Connection Reestablishment Reject), etc. Also, for example, an RRC reject message (RRC Reject), an RRC setup message (RRC Setup), etc. Also, other RRC messages may be included.

[0080] The RRC signaling sent in the uplink (UL) direction using the DCCH may include, for example, a Measurement Report message, an RRC connection reconfiguration complete message, an RRC connection setup complete message, an RRC connection reestablishment complete message, a security mode complete message, a UE capability information message, etc. Also, for example, a Measurement Report message, an RRC reconfiguration complete message, an RRC setup complete message, an RRC reestablishment complete message, an RRC resume complete message, a security mode complete message, a UE capability information message, etc. Other RRC signaling may also be included.

[0081] The RRC signaling sent in the downlink (DL) direction using the DCCH may include, for example, an RRC connection reconfiguration message, an RRC connection release message, a security mode command message, a UE capability inquiry message, etc. Also, for example, an RRC reconfiguration message, an RRC resume message, an RRC release message, an RRC reestablishment message, a security mode command message, a UE capability inquiry message, etc. Also, other RRC signaling may be included.

[0082] An example of the functions of the NAS will be described. The NAS may have an authentication function. The NAS may also have a function for performing mobility management. The NAS may also have a security control function.

[0083] The above-mentioned functions of PHY, MAC, RLC, PDCP, SDAP, RRC, and NAS are merely examples, and some or all of the functions may not be implemented. Also, some or all of the functions of each layer may be included in another layer.

[0084] Next, state transitions of the UE 122 in LTE and NR will be described. When the UE 122 connected to EPC or 5GC has an established RRC connection, the UE 122 may be in an RRC_CONNECTED state. The state in which the RRC connection is established may include a state in which the UE 122 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 the UE 122 can transmit and / or receive unicast data. The UE 122 may be in an RRC_INACTIVE state when the RRC connection is suspended. The UE 122 may be in the RRC_INACTIVE state when the UE 122 is connected to 5GC and the RRC connection is suspended. When the UE 122 is neither in the RRC_CONNECTED state nor in the RRC_INACTIVE state, the UE 122 may be in an RRC_IDLE state.

[0085] Note that when UE 122 is connected to the EPC, it does not have the RRC_INACTIVE state, but the E-UTRAN may initiate suspension of the RRC connection. When UE 122 is connected to the EPC, when the RRC connection is suspended, UE 122 may transition to the RRC_IDLE state while retaining the UE AS context and an identifier (resumeIdentity) used for resuming. A layer above the RRC layer of UE 122 (e.g., the NAS layer) may initiate the resumption of the suspended RRC connection when UE 122 retains the UE AS context, the E-UTRAN has permitted resumption of the RRC connection, and UE 122 needs to transition from the RRC_IDLE state to the RRC_CONNECTED state.

[0086] 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).

[0087] 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).

[0088] The UE context held by the UE 122 may be information including all or part of a PDU session context, a security key, UE radio capability information, and UE security capability information. Note that the UE context held by any or all of the eNB 102 and the gNB 108 may include the same information as the UE context held by the UE 122, or may include information different from the information included in the UE context held by the UE 122. Furthermore, the UE context may include all or part of the UE AS context, which will be described later.

[0089] The UE AS context held by the UE 122 may be information including all or some of the following: a current RRC configuration, a current security context, a PDCP state including a ROHC (Robust Header Compression) state, a C-RNTI (Cell Radio Network Temporary Identifier) ​​used in the source PCell, a cell identifier (cellIdentity), and a physical cell identifier of the source PCell. Note that the UE AS context held by one or all of the eNB 102 and the gNB 108 may include the same information as the UE AS context held by the UE 122, or may include information different from the information included in the UE AS context held by the UE 122.

[0090] The security context may be information that includes all or part of the following: encryption keys at the AS level, the Next Hop parameter (NH), the 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.

[0091] 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 configured, the serving cell may be configured with one primary cell (PCell). In addition, in a terminal device in an RRC connected state in which CA and / or DC, which will be described later, are configured, multiple serving cells may refer to a set of multiple cells (set of cell(s)) configured with one or multiple special cells (SpCells) and one or all of multiple 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 also be a cell used in the random access procedure during handover. The PSCell may be a cell used for 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 described above.

[0092] When a group of serving cells configured by a terminal device is composed of an SpCell and one or more SCells, it may be considered that the terminal device configures carrier aggregation (CA). Also, for a terminal device that configures CA, a cell that provides additional radio resources to the SpCell may refer to an SCell.

[0093] A group of serving cells configured by a terminal device through RRC, among which a group of serving cells using the same timing reference cell and the same timing advance value for a cell to which the terminal device configures uplink, may be referred to as a Timing Advance Group (TAG). A TAG including an SpCell of a MAC entity may refer to a Primary Timing Advance Group (PTAG). A TAG other than the above PTAG may refer to a Secondary Timing Advance Group (STAG). One or more TAGs may be configured for each cell group, which will be described later.

[0094] A cell group configured by a terminal device in a higher layer (such as RRC) will now be described. A cell group may be composed of one SpCell. A cell group may also be composed of one SpCell and one or more SCells. That is, 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)).

[0095] Dual Connectivity (DC) may be a technology for performing data communication using radio resources of cell groups configured by a first base station device (first node) and a second base station device (second node). When DC or MR-DC (described later) is performed, the 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). Also, 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). Also, the cell group configured by the secondary node may be called a secondary cell group (SCG). Note that the master node and the secondary node may be configured within the same base station device.

[0096] Furthermore, when a terminal device does not configure a DC, the cell group configured by the terminal device may be called an MCG. Furthermore, when a terminal device does not configure a DC, the SpCell configured by the terminal device may be a PCell. Furthermore, an NR in which a terminal device does not configure a DC may be called an NR standalone.

[0097] Note that 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 also be a technology that performs DC using NR for MCG and E-UTRA for SCG. MR-DC may also be a technology that performs DC using NR for both MCG and SCG. MR-DC may be a technology included in DC. Examples of MR-DC that use E-UTRA for MCG and NR for SCG include EN-DC (E-UTRA-NR Dual Connectivity) that uses EPC for the core network, and NGEN-DC (NG-RAN E-UTRA-NR Dual Connectivity) that uses 5GC for the core network. Examples of MR-DC that use NR for MCG and E-UTRA for SCG include NE-DC (NR-E-UTRA Dual Connectivity) that uses 5GC for the core network. Examples of MR-DC that use NR for both MCG and SCG include NR-DC (NR-NR Dual Connectivity) that uses 5GC for the core network.

[0098] In addition, in the terminal device, one MAC entity may exist for each cell group. For example, when the terminal device configures DC or MR-DC, there may be one MAC entity for the MCG and one MAC entity for the SCG. The MAC entity for the MCG in the terminal device may always be established in the terminal device in all states (such as RRC idle state, RRC connected state, and RRC inactive state). The MAC entity for the SCG in the terminal device may be created by the terminal device when the terminal device configures the SCG. 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 refer to the PCell. When the MAC entity is associated with the SCG, the SpCell may refer to the primary SCG cell (PSCell). When the MAC entity is not associated with a cell group, the SpCell may refer to the PCell. The PCell, PSCell, and SCell are serving cells. In the EN-DC and the 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. Also, 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. Also, in the NR-DC, the MAC entities for the MCG and the SCG may both be NR MAC entities. The existence of one MAC entity for each cell group may be rephrased as the existence of one MAC entity for each SpCell. Also, the existence of one MAC entity for each cell group may be rephrased as the existence of one MAC entity for each SpCell.

[0099] Radio bearers will now be described. When a terminal device communicates with a base station device, a radio connection may be established by establishing a radio bearer (RB) between the terminal device and the base station device. A radio bearer used for CP may be called a signaling radio bearer (SRB). A radio bearer used for UP may be called a data radio bearer (DRB). Each radio bearer may be assigned a radio bearer identity (ID). A radio bearer identifier for an SRB may be called an SRB identity (SRB ID). A radio bearer identifier for a DRB may be called a DRB identity (DRB ID). SRB0 to SRB2 may be defined for the SRB of E-UTRA, or other SRBs may be defined. SRB0 to SRB3 may be defined for the SRB of NR, or other SRBs may be defined. SRB0 may be an SRB for RRC messages 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 have a lower priority than SRB1. SRB3 may be an SRB for transmitting and / or receiving specific RRC signaling when the terminal device configures EN-DC, NGEN-DC, NR-DC, etc.All RRC and NAS signaling transmitted and / or received using SRB3 may use the logical channel DCCH. Other SRBs may also be provided for other uses. A DRB may be a radio bearer for user data. RRC signaling transmitted and / or received using a DRB may use the logical channel DTCH.

[0100] The radio bearer in the terminal device will now be described. The radio bearer may include an RLC bearer. The RLC bearer may consist of one or two RLC entities and logical channels. When an RLC bearer has two RLC entities, 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 consist of one RLC bearer. The RLC bearer of SRB0 may consist of a TM RLC entity and logical channels. SRB0 may always be established in the terminal device in all states (such as RRC idle state, RRC connected state, and RRC inactive state). SRB1 may be established in the terminal device and / or configured by the terminal device via 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 consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB1 may be composed of an AM RLC entity and a logical channel. SRB2 may be established in the terminal device and / or configured by the terminal device via RRC by RRC signaling received from the base station device by a terminal device in an RRC connected state with AS security activated. SRB2 may be composed of a PDCP entity and one or more RLC bearers. The RLC bearer of SRB2 may be composed of an AM RLC entity and a logical channel. Note that the PDCP on the base station device side of SRB1 and SRB2 may be placed in the master node. SRB3 may be established in the terminal device and / or configured by the terminal device via RRC by RRC signaling received from the base station device by a terminal device in an RRC connected state with AS security activated when a secondary node is added or changed in EN-DC, NGEN-DC, or NR-DC. SRB3 may be a direct SRB between the terminal device and the secondary node. The SRB3 may consist of one PDCP entity and one or more RLC bearers, and the RLC bearers of the SRB3 may consist of an RLC entity of the AM and logical channels.The PDCP on the base station side of SRB3 may be placed in a secondary node. One or more DRBs may be established in the terminal device and / or configured by the terminal device via RRC by RRC signaling received from the base station when the terminal device is in an RRC connected state with AS security activated. A DRB may consist of one PDCP entity and one or more RLC bearers. An RLC bearer of a DRB may consist of an AM or UM RLC entity and a logical channel.

[0101] In MR-DC, a radio bearer in which a PDCP is placed in the master node may be called an MN terminated bearer. In MR-DC, a radio bearer in which a PDCP is placed in a secondary node may be called an SN terminated bearer. In MR-DC, a radio bearer in which an RLC bearer exists only in an MCG may be called an MCG bearer. In MR-DC, a radio bearer in which an RLC bearer exists only in an SCG may be called an SCG bearer. In DC, a radio bearer in which an RLC bearer exists in both an MCG and an SCG may be called a split bearer.

[0102] When a terminal device configures an MR-DC, the bearer type of SRB1 and SRB2 established in and / or configured by the terminal device may be an MN terminated MCG bearer and / or an MN terminated split bearer. When a terminal device configures an MR-DC, the bearer type of SRB3 established in and / or configured by the terminal device may be an SN terminated SCG bearer. When a terminal device configures an MR-DC, the bearer type of the DRB established in and / or configured by the terminal device may be any of all bearer types.

[0103] For an RLC bearer that the terminal device establishes and / or configures in a cell group configured with E-UTRA, the RLC entity that the terminal device establishes and / or configures may be an E-UTRA RLC. Furthermore, for an RLC bearer that the terminal device establishes and / or configures in a cell group configured with NR, the RLC entity that the terminal device establishes and / or configures may be an NR RLC. When the terminal device configures an EN-DC, the PDCP entity that the terminal device establishes and / or configures for an MN-terminated MCG bearer may be either an E-UTRA PDCP or an NR PDCP. Furthermore, when the terminal device configures an EN-DC, the PDCP that the terminal device establishes and / or configures for radio bearers of other bearer types, i.e., an MN-terminated split bearer, an MN-terminated SCG bearer, an SN-terminated MCG bearer, an SN-terminated split bearer, and an SN-terminated SCG bearer, may be an NR PDCP. Also, when the terminal device configures NGEN-DC, NE-DC, or NR-DC, the PDCP entity that the terminal device establishes and / or configures for radio bearers of all bearer types may be an NR PDCP.

[0104] In NR, a DRB established and / or configured by a terminal device may be associated with one PDU session. The terminal device may establish and / or configure one SDAP entity for one PDU session. The SDAP entity, PDCP entity, RLC entity, and logical channel established and / or configured by the terminal device may be established and / or configured by the terminal device via RRC signaling received from a base station device.

[0105] Regardless of whether the terminal device configures MR-DC or not, a network configuration in which the master node is eNB102 and EPC104 is the core network may be called E-UTRA / EPC. Also, a network configuration in which the master node is eNB102 and 5GC110 is the core network may be called E-UTRA / 5GC. Also, a network configuration in which the master node is gNB108 and 5GC110 is the core network may be called NR or NR / 5GC. When the terminal device does not configure MR-DC, the above-mentioned master node may refer to a base station device that communicates with the terminal device.

[0106] The flow of RRC signaling transmitted and received between a terminal device and a base station device will be described. Fig. 4 is a diagram showing an example of a flow of a procedure for various settings in RRC according to this embodiment. Fig. 4 shows an example of a flow when RRC signaling is sent from a base station device (eNB102 and / or gNB108) to a terminal device (UE122).

[0107] 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 also create an RRC message in order to transmit RRC signaling that causes a specific terminal device to perform a process. The process that the specific terminal device is to perform may include, for example, security-related 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 setting, handover, security key update, etc. The base station device may also create an RRC message in order to respond to RRC signaling transmitted from the terminal device. A response to the RRC signaling transmitted from the 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. The RRC message includes 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 format known as ASN.1 (Abstract Syntax Notation One).

[0108] 4, the base station device then transmits the created RRC signaling to the terminal device (step S402). Next, the terminal device performs processing such as setting according to the received RRC signaling if necessary (step S404). After performing the processing, the terminal device may transmit RRC signaling as a response to the base station device (not shown).

[0109] RRC signaling may be used for other purposes, not limited to the above examples.

[0110] In MR-DC, the master node's RRC may be used to transfer RRC signaling for SCG-side configuration (cell group configuration, radio bearer configuration, measurement configuration, etc.) between the terminal device and the UE. 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 eNB 102 and UE 122. In NE-DC, NR RRC signaling may be included in the form of a container in NR RRC signaling transmitted and received between gNB 108 and UE 122. RRC signaling for SCG-side configuration may be transmitted and received between the master node and a secondary node.

[0111] Regardless of whether MR-DC is used or not, the RRC signaling for E-UTRA transmitted from eNB102 to UE122 may include RRC signaling for NR, and the RRC signaling for NR transmitted from gNB108 to UE122 may include RRC signaling for E-UTRA.

[0112] 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 related to 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. Note that the MobilityControlInfo information element may be referred to as a mobility control setting information element, mobility control setting, or mobility control information. Note that the ReconfigurationWithSync information element may be referred to as a reconfiguration with synchronization information element. Additionally or alternatively, the RRC signaling instructing the handover may be a message indicating movement to a cell of another RAT (e.g., MobilityFromEUTRACommand or MobilityFromNRCommand). The handover may be triggered by the RRC. Conditions for the terminal device to perform the handover may include some or all of the following: AS security is activated; the terminal device has established an SRB2; and at least one DRB is established.

[0113] An example of parameters included in a message related to RRC connection reconfiguration will be described. FIG. 7 shows an example of an ASN.1 description representing fields and / or information elements included in the message related to RRC connection reconfiguration in NR in FIG. 4. In the ASN.1 examples of this embodiment, including those shown in FIG. 7, the notation "<Omitted>" indicates that other information is omitted, not that it is part of the ASN.1 notation. Note that information elements may be omitted even when the notation "<Omitted>" is not used. In this embodiment, the ASN.1 example represents an example of parameters of RRC signaling in this embodiment, and other names and notations may be used. To avoid complication of explanation, only examples of main information closely related to this embodiment are shown in the ASN.1 example. Note that in each embodiment, parameters described in ASN.1 may be referred to as information elements without distinguishing between fields, information elements, etc. Furthermore, in each embodiment, fields and / or information elements described in ASN.1 included in RRC signaling may be referred to as information, and may also be referred to as parameters in addition to or instead of information. The message regarding the reconfiguration of the RRC connection may be an RRC reconfiguration message in NR. Also, the message regarding the reconfiguration of the RRC connection may be an RRC connection reconfiguration message in E-UTRA.

[0114] 7, the message regarding the reconfiguration of the 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. The message regarding the reconfiguration of the RRC connection may include a CellGroupConfig information element for setting an MCG and a CellGroupConfig information element for setting an SCG independently. The CellGroupConfig information element may also be referred to as a cell group setting information element or a cell group setting.

[0115] The CellGroupConfig information element may include a cellGroupId information element as identifier information for identifying this cell group.

[0116] The CellGroupConfig information element may include an RLC-BearerConfig information element as information used to configure an RLC entity.

[0117] The CellGroupConfig information element may include a MAC-CellGroupConfig information element as information used to configure MAC parameters in the cell group.

[0118] The CellGroupConfig information element may include a PhysicalCellGroupConfig information element as information used to configure PHY (L1) parameters specific to the cell group.

[0119] The CellGroupConfig information element may include an SpCellConfig information element as information used to configure parameters for the SpCell of the cell group. The SpCellConfig information element may also be referred to as an SpCell configuration information element or an SpCell configuration.

[0120] The CellGroupConfig information element may include an 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 also be referred to as an SCell configuration information element or SCell configuration.

[0121] The MAC-CellGroupConfig information element may include a TAG-Config information element as information used to configure parameters related to a TAG. The TAG-Config information element may include identifiers (TAG-Id) of one or more TAGs configured by the terminal device and values ​​of the time adjustment timers corresponding to the TAG identifiers.

[0122] The SpCellConfig information element may include a ServingCellConfig information element as information used to configure UE-specific parameters for the SpCell. Furthermore, the SCellConfig information element may include this ServingCellConfig information element as information used to configure UE-specific parameters for the SCell. The CellGroupConfig information element may include a ServingCellConfig information element for each serving cell to configure UE-specific parameters for the SpCell and each SCell. Each ServingCellConfig information element may include a TAG identifier (TAG-Id) indicating to which TAG in the cell group the serving cell belongs. Furthermore, the ServingCellConfig information element may include not only UE-specific parameters but also cell-specific parameters.

[0123] Each ServingCellConfig information element may include an initialDownlinkBWP indicating a BWP-DownlinkDedicated information element as a terminal device-specific setting for an 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 a first active downlink BWP identifier (firstActiveDownlinkBWP-Id), a BWP inactivity timer (bwp-InactivityTimer), and a default downlink BWP identifier (defaultDownlinkBWP-Id).

[0124] The ServingCellConfig information element for configuring UE-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).

[0125] The SCellConfig information element may include an RRC parameter (sCellState) indicating whether the SCell is activated or not when the SCell is configured. sCellState is also referred to as SCell state configuration. For example, if the SCellConfig information element includes sCellState, or alternatively, if the RRC entity of the terminal device sets sCellState included in the SCellConfig information element to activated, the MAC entity of the terminal device may activate the SCell, and in addition or alternatively, the RRC layer of the terminal device may configure a lower layer (such as a MAC entity) to consider the SCell to be activated. In addition or alternatively, 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 alternatively, the RRC layer of the terminal device may configure a lower layer (such as a MAC entity) to consider the SCell to be deactivated.

[0126] The ServingCellConfig information element for configuring terminal device-specific parameters for each SCell for which the terminal device does not configure a PUCCH may include an SCell inactivity timer.

[0127] 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).

[0128] The SpCellConfig information element may include a ReconfigurationWithSync information element as information including parameters required for synchronous reconfiguration processing from the source SpCell to the target SpCell. The ReconfigurationWithSync information element may be the above-mentioned synchronous reconfiguration information element. When the SpCellConfig information element of the MCG includes the ReconfigurationWithSync information element, the synchronous reconfiguration processing to the target SpCell may be a handover. When the SpCellConfig information element of the SCG includes the ReconfigurationWithSync information element, the synchronous reconfiguration processing to the target SpCell may be a PSCell addition or a PSCell modification.

[0129] 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 typically acquired from the SSB, MIB, or one or more SIBs of the cell when the terminal device accesses the cell from the idle state.

[0130] The ReconfigurationWithSync information element may include, for example, information on the value of C-RNTI used in the cell group of the target SpCell. The ReconfigurationWithSync information element may include, for example, information on the parameters of timer T304 (described later). The ReconfigurationWithSync information element may include, for example, a RACH-ConfigDedicated information element as information required for executing a contention-based random access (CBRA) procedure or a contention-free random access (CFRA) procedure in the target SpCell. The RACH-ConfigDedicated information element is also referred to as RACH dedicated configuration.

[0131] FIG. 8 is an example of an ASN.1 description representing fields and / or information elements related to the ServingCellConfigCommon information element included in the SCellConfig information element and the ReconfigurationWithSync information element in the SpCellConfig information element in FIG.

[0132] The ServingCellConfigCommon information element may include the physical cell identifier (physCellId) of the cell.

[0133] The ServingCellConfigCommon information element may include a DownlinkConfigCommon information element as information providing cell-specific (cell-common) downlink parameters. The DownlinkConfigCommon information element is also referred to as downlink common configuration.

[0134] The ServingCellConfigCommon information element may include an UplinkConfigCommon information element as information providing cell-specific (cell-common) uplink parameters. The UplinkConfigCommon information element is also referred to as uplink common configuration.

[0135] The ServingCellConfigCommon information element may include the value of N_{TA,offset} that applies to all uplink transmissions in that cell.

[0136] The DownlinkConfigCommon information element may include a FrequencyInfoDL information element as basic information related to a downlink carrier and transmission on the downlink carrier. For example, the FrequencyInfoDL information element may include frequency information of an SSB.

[0137] The DownlinkConfigCommon information element may include an initialDownlinkBWP indicating the BWP-DownlinkCommon information element as the initial downlink BWP configuration for the cell. Additionally or alternatively, the DownlinkConfigCommon information element may include an initialDownlinkBWP-RedCap indicating the BWP-DownlinkCommon information element to be used by one or more performance-limited terminals (RedCap UEs) instead of the initialDownlinkBWP. The BWP-DownlinkCommon information element is also referred to as a downlink BWP common configuration.

[0138] The BWP-DownlinkCommon information element may include a BWP information element as information for the terminal device to set generic parameters of the BWP.

[0139] The BWP-DownlinkCommon information element may include a PDCCH-ConfigCommon information element as information for the terminal device to configure cell-specific parameters for the PDCCH of this BWP. The PDCCH-ConfigCommon information element is also referred to as PDCCH common configuration.

[0140] The BWP-DownlinkCommon information element may include a PDSCH-ConfigCommon information element as information for the terminal device to configure cell-specific parameters for the PDSCH of this BWP. The PDSCH-ConfigCommon information element is also referred to as PDSCH common configuration.

[0141] The PDCCH-ConfigCommon information element may include a SearchSpaceZero information element as information for the terminal device to set parameters of a common search space (CSS) #0. This SearchSpaceZero information element may be included in the PDCCH-ConfigCommon information element only when the BWP is an initial downlink BWP.

[0142] The PDCCH-ConfigCommon information element may include a ControlResourceSetZero information element as information for the terminal device to configure parameters of a 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 when the BWP is an initial downlink BWP.

[0143] The PDCCH-ConfigCommon information element may include a ControlResourceSet information element as information for the terminal device to configure parameters of an additional common CORESET.

[0144] The PDCCH-ConfigCommon information element may include a list (commonSearchSpaceList) of information elements (SearchSpace information elements) indicating the configuration of one or more additional CSSs.

[0145] The PDCCH-ConfigCommon information element may include information (searchSpaceSIB1) indicating which CSS setting in the commonSearchSpaceList is the search space setting for the system information (SIB1).

[0146] The PDCCH-ConfigCommon information element may include information (searchSpaceOtherSystemInformation) indicating which CSS in the commonSearchSpaceList is used as the search space setting for system information (SIB2 and subsequent information).

[0147] The PDCCH-ConfigCommon information element may include information (pagingSearchSpace) indicating which CSS in the commonSearchSpaceList is used to configure the search space for the paging message.

[0148] The UplinkConfigCommon information element may include a FrequencyInfoUL information element as the configuration of the absolute uplink frequency and multiple subcarrier-specific virtual carriers. For example, the FrequencyInfoUL information element may include information indicating the maximum transmit power.

[0149] The UplinkConfigCommon information element may include an initialUplinkBWP indicating the BWP-UplinkCommon information element as the initial uplink BWP configuration for the cell. Additionally or alternatively, the UplinkConfigCommon information element may include an initialUplinkBWP-RedCap indicating the BWP-UplinkCommon information element to be used by one or more performance-limited terminals (RedCap UEs) instead of the initialUplinkBWP. The BWP-UplinkCommon information element is also referred to as an uplink BWP common configuration.

[0150] The BWP-UplinkCommon information element may include a BWP information element as information for the terminal device to set generic parameters of the BWP.

[0151] The BWP-UplinkCommon information element may include a PUCCH-ConfigCommon information element as information for the terminal device to configure cell-specific parameters for the PUCCH of this BWP. The PUCCH-ConfigCommon information element is also referred to as PUCCH common configuration.

[0152] The BWP-UplinkCommon information element may include a PUSCH-ConfigCommon information element as information for the terminal device to configure cell-specific parameters for the PUSCH of this BWP. The PUSCH-ConfigCommon information element is also referred to as PUSCH common configuration.

[0153] The BWP-UplinkCommon information element may include a RACH-ConfigCommon information element as information for the terminal device to configure cell-specific random access parameters. The RACH-ConfigCommon information element is also referred to as RACH common configuration.

[0154] Each of the above information elements may include information other than the information described above.

[0155] The RRC reconfiguration procedure will be described. The RRC reconfiguration procedure may be a procedure by which a terminal device modifies 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 a radio bearer; (B) Performing synchronized reconfiguration; (C) Setting up, modifying, and / or releasing measurements; (D) Adding, modifying, and / or releasing an SCell and a cell group; (E) Adding, modifying, and / or releasing a conditional handover (CHO) configuration; (F) Adding, modifying, and / or releasing a conditional PSCell change (CPC) or conditional PSCell addition (CPA) configuration.

[0156] A base station apparatus (network) may initiate an RRC reconfiguration procedure for a terminal apparatus in an RRC_CONNECTED state. Note that "a base station apparatus initiates an RRC reconfiguration procedure for a terminal apparatus" may be rephrased as "a base station apparatus transmits a message regarding reconfiguration of an RRC connection to a terminal apparatus."

[0157] When receiving a message regarding RRC connection reconfiguration or when executing conditional reconfiguration (CHO, CPA, or CPC), the terminal device may perform some or all of (A) to (D) of the following process RRP. (Process RRP) (A) If the message regarding RRC connection reconfiguration includes a cell group configuration of an MCG, the terminal device performs 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, the terminal device performs synchronized reconfiguration. (B) If the message regarding RRC connection reconfiguration includes a cell group configuration of an SCG, the terminal device performs cell group configuration using the cell group configuration. In addition, if the cell group configuration includes an SpCell configuration with a synchronized reconfiguration information element, the terminal device performs synchronized reconfiguration. (C) If the message regarding RRC connection reconfiguration includes information regarding conditional reconfiguration, the terminal device performs a configuration procedure for conditional reconfiguration using the information regarding 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.

[0158] To execute synchronized reconfiguration, the terminal device may perform some or all of steps (A) to (E) of the following process RWS. "Executing synchronized reconfiguration" may be rephrased as "performing synchronized reconfiguration" or "triggering synchronized reconfiguration." (Process RWS) (A) If the synchronized reconfiguration information element includes a frequencyInfoDL information element, the terminal device determines that the target SpCell is a cell located at the SSB frequency indicated by the frequencyInfoDL information element and indicated by the physical cell identifier included in the synchronized reconfiguration information element. If the synchronized reconfiguration information element does not include a frequencyInfoDL information element, the terminal device determines that the target SpCell is a cell located at the same SSB frequency as the source SpCell and indicated by the physical cell identifier included in the synchronized reconfiguration information element. (B) Initiate downlink synchronization to the target SpCell. (C) If the terminal device does not have timing information required for the random access procedure, acquire the MIB of the target SpCell. (C) Reset the MAC entity of the cell group to be subjected to 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 synchronized reconfiguration. (E) Configure the lower layers of the RRC (PHY, etc.) according to the SpCell common configuration.

[0159] Conditional reconfiguration will now be described. A terminal device receives one or more conditional reconfiguration information elements from the network, and thereby configures candidate target SpCells associated with the conditional reconfiguration information elements received from the network. The terminal device evaluates the states 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 an execution condition. The terminal device may also retain a list of entries (VarConditionalReconfig) described below for conditional reconfiguration.

[0160] 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, and may be referred to as a conditional PSCell addition and / or a conditional PSCell modification if the candidate target SpCell is an SpCell (i.e., a PSCell) of an SCG.

[0161] As a setting process for conditional reconfiguration, a terminal device may, based on receiving information about conditional reconfiguration (e.g., a conditional reconfiguration information element), delete (remove) the conditional reconfiguration settings specified in the entry deletion list from the settings held by the terminal device if the information about the conditional reconfiguration includes an entry deletion list (condReconfigToRemoveList). Specifically, if 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.

[0162] In the following description, the list of conditional reset entries held by the terminal device will also be simply referred to as the entry list. In other words, the "entry list" in the following description 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 identifier of an entry will also be simply referred to as the entry identifier.

[0163] When the information regarding conditional reconfiguration includes an entry add / modify list (condReconfigToAddModList), the terminal device may add or modify the conditional reconfiguration configuration included in the entry add / modify list to the configuration held by the terminal device as a configuration process for conditional reconfiguration. The entry add / modify list may be a list of one or more conditional reconfiguration information elements. The terminal device may configure each entry with the conditional reconfiguration information element. The conditional reconfiguration information element may include an entry identifier, an execution condition, and a conditional RRC reconfiguration information element.

[0164] Specifically, when an entry identifier included in the addition modification list of an entry exists in an entry in the entry list, the terminal device may perform the following processes (A) and / or (B): (A) When 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) When an entry included in the addition 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 addition modification list of that entry.

[0165] Furthermore, if an entry identifier included in the entry addition / modification list is not included in the entry list, the terminal device may add a new entry corresponding to the entry identifier not included in the entry list to the entry list.

[0166] 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 of the CHO, CPA, and CPC entries. 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 any entries, the terminal device may hold an empty list. The execution condition may be a condition that needs to be met to trigger execution of a conditional reconfiguration. The conditional RRC reconfiguration information element may be a message related to reconfiguration of an RRC connection that is applied when the execution condition is met. The message related to reconfiguration of an RRC connection may be a message used to connect to a candidate target SpCell.

[0167] 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.

[0168] Executing a conditional RRC reconfiguration may mean that the terminal device evaluates 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 an entry including the execution condition. Applying a conditional RRC reconfiguration information element may mean executing an RRC reconfiguration procedure using the conditional RRC reconfiguration information element.

[0169] If there are multiple entries that satisfy the execution conditions, the terminal device may select one entry from the multiple entries that satisfy the execution conditions and apply the conditional RRC reconfiguration information element of the selected entry.

[0170] When a reset of the MAC entity is requested from a higher layer (e.g., RRC), the MAC entity of the terminal device may perform some or all of the following processes (A) to (N) of 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 a higher layer (e.g., RRC), the MAC entity of the terminal device may perform some or all of the following processes (A) to (N) of MR. The partial reset of the MAC entity may be simply referred to as a partial MAC reset. The processes performed in a partial MAC reset may be processes in which only some of the processes performed in a MAC reset are performed. The processes performed in a partial MAC reset may be processes in which some of the processes performed in a MAC reset are 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 the RRC entity of the terminal device instructing the MAC entity of the terminal device to perform a partial MAC reset.

[0171] (Process MR) (A) Initialize the parameter Bj set by the terminal device for each logical channel to 0. (B) Stop all running timers except for at least some timers, including the time adjustment timer. (C) Set the New Data Indicator (NDI) value of all uplink HARQ processes to 0. (D) Stop the ongoing random access procedure, if any. (E) Discard the explicitly signaled contention-free random access (CFRA) resources for 4-step and 2-step RA types, if any. (F) Flush the Msg3 buffer. (G) Flush the MSGA buffer. (H) Cancel the Scheduling Request (SR) procedure, if any. (I) Cancel the Buffer Status Reporting (BSR) procedure, if any. (J) Cancel the Power Headroom Reporting (PHR) procedure, if any. (K) Flushes the soft buffers of all downlink HARQ processes. (L) If a Beam Failure Reporting (BFR) is triggered, cancel the BFR. (M) If a Temporary C-RNTI is present, release the Temporary C-RNTI. (N) Resets all BFI_COUNTERs.

[0172] An RRC connection re-establishment procedure will be described. The RRC connection re-establishment procedure may be a procedure by which a terminal device re-establishes an RRC connection based on an RRC re-establishment message. The RRC connection re-establishment procedure may also be referred to as an RRC re-establishment procedure. In the RRC connection re-establishment procedure, the terminal device may transmit an RRC re-establishment request message (RRCReestablishmentRequest) to a base station device (network), and then determine that the RRC connection re-establishment has been successful based on receiving an RRC re-establishment message (RRCReestablishment) from the base station device, and transmit an RRC re-establishment complete message (RRCReestablishmentComplete) to the base station device. The order in which the terminal device determines that the RRC connection re-establishment has been successful and transmits the RRC re-establishment complete message to the base station device may be either first or second. Furthermore, a terminal device in an RRC_CONNECTED state may initiate the procedure to continue the RRC connection. The re-establishment of the RRC connection is successful if the base station device can find and verify a valid UE context (that is, the UE context held by the terminal device), or if the UE context cannot be obtained, the base station device may reply with an RRC setup message.

[0173] When the terminal device initiates the RRC connection re-establishment procedure, it may perform some or all of the following steps (A) to (F) of the RRI procedure. (Process RRI) (A) Stop timer T304 if it is running. (B) Reset the MAC entity. (C) Release the SpCell configuration if the terminal device has configured it. (D) Suspend all radio bearers except SRB0. (E) Release one or more SCells of the MCG if the terminal device has configured it. (F) Perform cell selection, and if a suitable NR cell is selected, perform some or all of the following steps (F-1) to (F-8).

[0174] (F-1) Ensure that valid and up-to-date essential system information is available. (F-2) Reset the MAC entity. (F-3) Release the SpCell configuration if configured by the terminal device. (F-4) Release one or more SCells in the MCG if configured by the terminal device. (F-5) Apply the default L1 parameter(s) other than the value provided in SIB1 as the value of the corresponding physical layer specification. (F-6) Apply the default MAC Cell Group configuration. (F-7) Apply the CCCH configuration. (F-8) Start transmitting an RRC re-establishment request message.

[0175] The timer T304 may be started when the terminal device receives a message regarding reconfiguration of the RRC connection including a synchronization-with-reconfiguration information element, and may be stopped when the random access procedure on the SpCell corresponding to the synchronization-with-reconfiguration information element is successfully completed. Furthermore, when the timer T304 expires, the terminal device may start an RRC connection re-establishment procedure.

[0176] Here, the band portion (BWP) will be explained.

[0177] A BWP may be a part or all of the band of the serving cell. A BWP may also be referred to as a carrier BWP. A terminal device may configure one or more BWPs. A terminal device may configure a certain BWP based on information included in system information associated with a synchronization signal detected in an initial cell search. A certain BWP may also be a frequency bandwidth associated with a frequency at which an initial cell search is performed. A terminal device may also receive a certain BWP from a base station device via RRC signaling (e.g., dedicated RRC signaling) and configure the received BWP via RRC. A terminal device may also configure a downlink BWP (DL BWP) and an uplink BWP (UL BWP) separately. One or more uplink BWPs may also be associated with one or more downlink BWPs. Furthermore, the correspondence between the uplink BWP and the downlink BWP may be a predetermined 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 a downlink control channel), or may be a combination thereof. Furthermore, the terminal device may set a CORESET in the downlink BWP.

[0178] A BWP may be configured by a group of consecutive physical resource blocks (PRBs). A terminal device in a connected state may set parameters for the BWP (one or more BWPs) of each component carrier. The BWP parameters of each component carrier may include some or all of: (A) cyclic prefix type, (B) subcarrier spacing, (C) frequency location of the BWP (e.g., start location or center frequency location on the lower frequency side of the BWP) (for example, ARFCN may be used as the frequency location, or an offset from a specific subcarrier of the serving cell may be used. The offset may be in units of subcarriers or in units of resource blocks. The terminal device may configure both the ARFCN and the offset), (D) BWP bandwidth (e.g., the number of PRBs), (E) resource configuration information of the control signal, and (F) center frequency location of the SS block (for example, ARFCN may be used as the frequency location, or an offset from a specific subcarrier of the serving cell may be used. The offset may be in units of subcarriers or in units of resource blocks. The terminal device may configure both the ARFCN and the offset). 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.

[0179] A terminal device may transmit and receive in an Active BWP among one or more configured BWPs. A terminal device may configure one or more BWPs in an associated serving cell. A terminal device may configure one or more BWPs among one or more BWPs configured for an associated serving cell so that at a certain time, at most one uplink BWP and / or at most one downlink BWP is 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 by a terminal device, a BWP that is not an Active BWP may be referred to as an Inactive BWP.

[0180] Next, we will explain the activation / deactivation of BWPs. Activating a BWP may mean activating a BWP or activating an inactive BWP. Deactivating a BWP may mean deactivating a BWP or deactivating an active BWP. BWP switching in the serving cell is used to activate an inactive BWP and deactivate an active BWP.

[0181] BWP switching is controlled by the PDCCH indicating a downlink assignment or uplink grant, the BWP inactivity timer, RRC signaling, or the MAC entity itself due to the initiation of a random access procedure. The active BWP of the serving cell is indicated by RRC or PDCCH.

[0182] Next, the BWP inactivity timer will be explained. For each activated serving cell for which the terminal device has set a BWP inactivity timer, the MAC entity performs the following (A). The BWP inactivity timer may also be a timer named bwp-InactivityTimer. (A) If any of the following (A-1) to (A-4) is satisfied, the MAC entity performs the following (B) and (D). (A-1) The UE has set a default downlink BWP identifier (defaultDownlinkBWP-Id), and 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 UE has not configured a default downlink BWP identifier (defaultDownlinkBWP-Id), 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 UE has not configured a default downlink BWP identifier (defaultDownlinkBWP-Id), the UE has not configured an initial downlink BWP for a performance-limited terminal (initialDownlinkBWP-RedCap), and the Active DL BWP is not the initialDownlinkBWP. (A-4) The UE is a performance-limited terminal (RedCap UE), the UE has not set the identifier of the default downlink BWP (defaultDownlinkBWP-Id), the UE has set the initial downlink BWP (initialDownlinkBWP-RedCap) for the performance-limited terminal, and the Active DL BWP is not initialDownlinkBWP-RedCap.(B) If a PDCCH addressed to the C-RNTI or CS-RNTI indicating a downlink assignment or uplink grant for an Active BWP is received, or if a PDCCH addressed to the C-RNTI or CS-RNTI indicating a downlink assignment or uplink grant for an Active BWP is received, or if a MAC PDU is transmitted with a configured uplink grant or a MAC PDU is received with a configured downlink assignment, the MAC entity shall perform (C) below. (C) If a random access procedure associated with this serving cell is not ongoing or an ongoing random access procedure associated with this serving cell is successfully completed by receiving a PDCCH addressed to the C-RNTI, the MAC entity shall start or restart the BWP inactivity timer associated with the Active DL BWP. (D) If the BWP inactivity timer associated with the Active DL BWP expires, the MAC entity shall perform (E) below. (E) If the UE has configured a defaultDownlinkBWP-Id, the MAC entity performs BWP switching to the BWP indicated by this defaultDownlinkBWP-Id, otherwise the MAC entity performs the following (F): (F) If the UE is a performance-limited terminal (RedCap UE) and the UE has configured an initial downlink BWP for a performance-limited terminal (initialDownlinkBWP-RedCap), the MAC entity performs BWP switching to this initialDownlinkBWP-RedCap, otherwise the MAC entity performs BWP switching to the initialDownlinkBWP.

[0183] 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, it starts or restarts the BWP inactivity timer associated with the Active DL BWP. (A-1) If the UE has configured a default downlink BWP identifier (defaultDownlinkBWP-Id), and the MAC entity switches to a downlink BWP that is not indicated by either the defaultDownlinkBWP-Id or the dormant BWP identifier (dormantBWP-Id). (A-2) If the UE is not a performance-limited terminal (RedCap UE), the UE has not configured a default downlink BWP identifier (defaultDownlinkBWP-Id), 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 UE has not configured a default downlink BWP identifier (defaultDownlinkBWP-Id), the UE has not configured an initial downlink BWP for a performance-limited terminal (initialDownlinkBWP-RedCap), 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 UE has not configured a default downlink BWP identifier (defaultDownlinkBWP-Id), the UE has configured an initial downlink BWP for a performance-limited terminal (initialDownlinkBWP-RedCap), and the MAC entity switches to a downlink BWP other than the initialDownlinkBWP-RedCap.

[0184] In each activated serving cell for which the UE has configured a BWP, the MAC entity performs some or all of the following (A) to (H) if the BWP is activated (Active BWP) and the Active DL BWP in that serving cell is not a dormant BWP: (A) Transmits the UL-SCH in that BWP; (B) If the UE has configured a PRACH occasion, transmits the RACH (PRACH) in that BWP; (C) Monitors the PDCCH in that BWP; (D) If the UE has configured a PUCCH, transmits the PUCCH in that BWP; (E) Reports CSI in that BWP; (F) If the UE has configured SRS, transmits the SRS in that BWP; and (G) Receives the DL-SCH in that BWP. (H) (re)initialize all suspended configured uplink grants of grant type 1 that the UE has set in its Active BWP according to the stored configuration, if any.

[0185] If a BWP is activated (Active BWP) and the Active DL BWP in its serving cell is a dormant BWP, the MAC entity shall perform some or all of the following (A) to (L): (A) Stop the BWP inactivity timer of this serving cell if it is running; (B) Do not monitor the PDCCH in that BWP; (C) Do not monitor the PDCCH for that BWP; (D) Do not receive DL-SCH in that BWP; (E) Do not report CSI in that BWP and report CSI excluding aperiodic CSI for that BWP; (F) Do not transmit SRS in that BWP; (G) Do not transmit UL-SCH in that BWP; (H) Do not transmit RACH in that BWP; (I) Do not transmit PUCCH in that BWP; and (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.

[0186] If the BWP is deactivated, the MAC entity shall do some or all of the following (A) to (I): (A) Do not transmit UL-SCH in that BWP. (B) Do not transmit RACH in that BWP. (C) Do not monitor PDCCH in that BWP. (D) Do not transmit PUCCH in that BWP. (E) Do not report CSI in that BWP. (F) Do not transmit SRS in that BWP. (G) Do not receive DL-SCH in that BWP. (H) Clear all configured downlink assignments and / or all configured uplink grants of grant type 2 that the UE has set in that BWP. (I) Suspend all configured uplink grants of grant type 1 in that inactive BWP.

[0187] A random access procedure initiated by a PDCCH order will now be described. The random access procedure initiated by a PDCCH order may be a random access procedure including a procedure in which a random access preamble identifier is explicitly provided by a PDCCH order (PDCCH). The random access preamble identifier may be, for example, a 6-bit identifier named ra-PreambleIndex. The random access preamble identifier may be indicated by the above-mentioned RACH-ConfigDedicated information element. Furthermore, the PDCCH order may be, for example, a PDCCH that transmits DCI for scheduling a PDSCH within one downlink cell, named DCI format 1_0. Additionally or alternatively, the PDCCH order and / or the DCI format 1_0 may include an identifier (SS / PBCH block index field) of an SS / PBCH (SSB) used to determine a RACH occasion (PRACH occasion) for PRACH transmission, if the value of the identifier of the random access preamble is not all zeros, and / or an identifier (PRACH mask index field) of a PRACH mask (PRACH mask) indicating the RACH occasion associated with the SS / PBCH. Note that in the following description, the terms "random access preamble" and "PRACH" may be interchangeable.

[0188] When a random access procedure is initiated on a serving cell by a PDCCH order, the terminal device may transmit a PRACH on this serving cell. For example, when a random access procedure is initiated on a PCell by a PDCCH order, the terminal device may transmit a PRACH on this PCell. Additionally or alternatively, when a random access procedure is initiated on an SCell by a PDCCH order, the terminal device may transmit a PRACH on this SCell. Note that "when a random access procedure is initiated on a serving cell by a PDCCH order" may be rephrased as "when the terminal device receives a PDCCH (PDCCH order) in a serving cell that explicitly provides an identifier of a random access preamble," etc.

[0189] In a random access procedure with a 4-step RA type, if a random access preamble identifier is explicitly provided by the PDCCH, the MAC entity of the terminal device may perform the following (a) and / or (b) if the value of the random access preamble identifier is not all 0: (a) set a preamble identifier (PREAMBLE_INDEX) to the value of the signaled random access preamble identifier; (b) select an SSB signaled by the PDCCH.

[0190] In a random access procedure with a 4-step RA type, the MAC entity of the terminal device may calculate a random access identifier (RA-RNTI) associated with a PRACH occasion on which a random access preamble is transmitted, and instruct the PHY layer to transmit the random access preamble using the selected PRACH occasion, the corresponding random access identifier (RA-RNTI), and / or the preamble identifier. When a higher layer (e.g., a MAC entity) requests transmission of a random access preamble, the PHY layer of the terminal device may transmit a PRACH within the selected PRACH occasion. In this case, the time between the last symbol receiving the PDCCH order and the first symbol transmitting the PRACH may be greater than or equal to N_{T,2} + Δ_BWPSwitching + Δ_Delay + T_switch milliseconds (msec). where N_{T,2} may be a time interval of N_2 symbols corresponding to the PUSCH preparation time. Additionally or alternatively, Δ_BWPSwitching may be a delay incurred in BWP switching, and if the Active UL BWP is not changed, the value of Δ_BWPSwitching may be 0. Additionally or alternatively, the value of Δ_Delay may be 0.5 milliseconds (msec) in the frequency range 410 MHz - 7125 MHz (Frequency range 1: FR1) or 0.25 msec in the frequency range 24250 MHz - 52600 MHz (Frequency range 2: FR2 or Frequency range 2-1: FR2-1). Additionally or alternatively, T_switch may be a switching gap duration.

[0191] Once the random access preamble is transmitted, regardless of the potential occurrence of measurement gaps, the UE MAC entity may start a random access response window (ra-ResponseWindow) configured by the UE RRC entity in the RACH-ConfigCommon information element on the first PDCCH occasion and monitor the SpCell's PDCCH for one or more Random Access Responses (RARs) identified by the Random Access Identifier (RA-RNTI) while the Random Access Response window is running. The UE MAC entity may consider the reception of a Random Access Response successful if it receives a valid downlink assignment on the PDCCH for the Random Access Identifier (RA-RNTI), successfully decodes the received Transport Block (TB), and the received Random Access Response contains a MAC sub-PDU with a Random Access Preamble identifier corresponding to the transmitted PREAMBLE_INDEX.

[0192] If the MAC entity of the terminal device considers that it has successfully received a random access response, and if the received random access response contains only a MAC subPDU with RAPID, it considers that the random access procedure has been successfully completed and notifies a higher layer (such as the RRC layer) that it has received an acknowledgement for the SI request. Otherwise (if the received random access response contains a MAC subPDU with RAPID and a MAC RAR), it may apply some or all of the following actions (a) to (c) to the serving cell that transmitted the random access preamble. Note that the above MAC RAR may include some or all of a Timing Advance Command (TAC), an uplink grant, and / or a Temporary C-RNTI (Temporary C-RNTI), as described below. (a) Process the Timing Advance Command (TAC), as described below. (b) Notify a lower layer (such as a PHY layer) of a parameter (preambleReceivedTargetPower) of the received power (target power) of the random access preamble in the base station device and the amount of power ramping applied when the random access preamble was last transmitted. (c) If a random access procedure for an SCell is performed on an uplink carrier for which the terminal device has not configured a PUSCH parameter specific to the terminal device (UE specific PUSCH parameter: PUSCH-Config), ignore the received uplink grant; otherwise, process the value of the received uplink grant and notify the value to a lower layer (such as a PHY layer).

[0193] The terminal device may adjust the uplink transmission timing. For example, the terminal device may adjust the uplink transmission timing based on the reception of a Timing Advance Command (TAC) MAC CE. A group of serving cells configured by the terminal device through RRC, among which a group of serving cells using the same timing reference cell and the same timing advance value for a cell to which the terminal device configures an uplink, may be referred to as a Timing Advance Group (TAG). A TAG including an SpCell of a MAC entity may be referred to as a Primary Timing Advance Group (PTAG). A TAG other than the above PTAG may be referred to as a Secondary Timing Advance Group (STAG). Note that one or more of the TAGs may be configured independently for each cell group.

[0194] For example, upon receiving a TAC MAC CE for a certain TAG, the terminal device may adjust the uplink transmission timing for transmitting PUSCH, SRS, and / or PUCCH in some or all serving cells in that TAG. The terminal device may adjust the uplink transmission timing so that it is earlier by T_TA relative to the timing of the beginning of the downlink frame with the same frame number. The terminal device may calculate the timing advance value T_TA based on N_TA and a TA offset (N_{TA,offset}). The terminal device may set N_TA based on information included in the TAC MAC CE. The terminal device may set the TA offset (N_{TA,offset}) based on an RRC parameter (n-TimingAdvanceOffset) set by the terminal device for each serving cell. The terminal device sets N_{TA,offset} for each serving cell, but N_{TA,offset} may have the same value for serving cells of the same TAG.

[0195] In addition, in dual connectivity, cells in each cell group may belong to different TAGs, i.e., the PTAG of the MCG and the PTAG of the SCG may be independent and different TAGs.

[0196] The RRC entity of the terminal device may set the value of a time alignment timer (timeAlignmentTimer) in the MAC to maintain uplink time alignment. The time alignment timer may be used to control the time at which the MAC entity considers the uplink time of a serving cell belonging to a TAG associated with the time alignment timer to be aligned. The terminal device may set the value of the time alignment timer using RRC signaling received from the base station device.

[0197] The MAC entity of the terminal device may apply a TAC to the TAG indicated by the Timing Advance Command (TAC) MAC CE based on receiving the TAC MAC CE and maintaining the N_TA of the TAG indicated by the TAC MAC CE. The MAC of the terminal device may also start, or restart if already running, a time alignment timer (timeAlignmentTimer) associated with the TAG indicated by the TAC MAC CE based on receiving the TAC MAC CE and maintaining the N_TA of the TAG indicated by the TAC MAC CE.

[0198] The MAC entity of the terminal device may apply a TAC to a TAG based on receiving a Timing Advance Command (TAC) in a Random Access Response (RAR) message for a serving cell belonging to the TAG and based on the random access preamble not being selected by the MAC entity from among contention-based random access preambles (e.g., the random access preamble's identifier was explicitly provided in a PDCCH order). Additionally or alternatively, the MAC entity of the terminal device may start, or restart if already running, a time alignment timer associated with the TAG based on receiving a Timing Advance Command (TAC) in a Random Access Response (RAR) message for a serving cell belonging to the TAG and based on the random access preamble not being selected by the MAC entity from among contention-based random access preambles.

[0199] When the time adjustment timer associated with a PTAG expires, the MAC entity of the terminal device may perform some or all of the following processes (A) to (G): (A) Flushes all HARQ buffers for all serving cells (within a cell group). (B) If the terminal device has configured a PUCCH, notifies RRC that it has released the PUCCH for all serving cells. (C) If the terminal device has configured an SRS, notifies RRC that it has released the SRS for all serving cells. (D) Clears all configured downlink assignments and configured uplink grants. (E) Clears all PUSCHs for semi-persistent CSI reporting. (F) Considers all time adjustment timers, including those for STAGs, to have expired. (G) Maintains the N_TA for all TAGs.

[0200] When the time adjustment timer associated with a STAG expires, the MAC entity of the terminal device may perform some or all of the following processes (A) to (F) for all serving cells belonging to this STAG: (A) Flushes all HARQ buffers. (B) If the terminal device has configured a PUCCH, notifies RRC that the PUCCH has been released. (C) If the terminal device has configured an SRS, notifies RRC that the SRS has been released. (D) Clears all configured downlink assignments and configured uplink grants. (E) Clears all PUSCHs for semi-persistent CSI reporting. (F) Maintains the N_TA for this TAG.

[0201] The terminal device may determine not to perform uplink transmissions in all serving cells other than transmitting a random access preamble in the SpCell and transmitting an MSGA (in the 2-step RACH) based on the fact that one or more time adjustment timers associated with the PTAG are not running.

[0202] This section describes multiple Transmit / Receive Point (also referred to as multi-TRP or mTRP) operation.

[0203] In mTRP operation, the serving cell may be able to schedule a terminal device from multiple TRPs (Transmit / Receive Points) to provide better coverage, reliability, and / or data rates for the PDSCH, PDCCH, PUSCH, and PUCCH.

[0204] There may be two different operation modes for scheduling PDSCH transmissions of mTRPs. The two operation modes may be single-DCI and multi-DCI. Control of uplink and downlink operations for both modes may be performed at the PHY and MAC layers using parameters configured by the terminal device at the RRC layer. In single-DCI mode, the terminal device may be scheduled for both TRPs using the same DCI. In multi-DCI mode, the terminal device may be scheduled for each TRP using independent DCI.

[0205] 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 a 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.

[0206] There may be two different operation modes for scheduling PDCCH transmissions of mTRPs. 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 PDCCH transmission 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.

[0207] 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.

[0208] 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.

[0209] In inter-cell mTRP operation, one or more TCI states in a multi-DCI PDSCH transmission may be associated with SSBs of a Physical Cell Identity (PCI) different from the PCI of the serving cell, and at most one TCI state associated with a PCI different from the serving cell may be active at a time.

[0210] 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.

[0211] Next, the layer 1 / layer 2 triggered mobility (LTM) in this embodiment will be described.

[0212] Layer 1 / Layer 2 triggered mobility may be a procedure in which a base station device transmits a MAC CE that causes a terminal device to identify one or more cells that are targets (destinations for changing) of the serving cell, and instructs the terminal device to switch (change) the one or more serving cells through the MAC CE. Additionally or alternatively, Layer 1 / Layer 2 triggered mobility may be a procedure in which a terminal device receives a MAC CE from a base station device that identifies one or more cells that are targets of the serving cell, and switches (changes) the serving cell to one or more cells indicated by the MAC CE.

[0213] For example, a MAC CE that identifies one or more cells that are targets of a 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, for example, identifiers associated with information about one or more serving cell targets that is pre-configured by a terminal device using RRC signaling received from a base station device. Furthermore, the identifiers may be, for example, identifiers for LTM candidate target configuration (described later) that is applied for Layer 1 / Layer 2 triggered mobility. Note that the identifiers may be referred to as LTM candidate target indexes.

[0214] In Layer 1 / Layer 2 triggered mobility, a base station device may determine a target serving cell based on a measurement report provided from a 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 CSI report transmitted from the terminal device on a PUCCH. 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. Furthermore, the measurement report may be other information.

[0215] In addition, "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", "Layer 1 / Layer 2 inter-cell mobility", "LTM processing", "LTM serving cell switching processing", "LTM serving cell switching", "LTM cell switching processing", "LTM cell switching", "LTM serving cell change processing", "LTM serving cell change", "LTM cell change", "Layer 1 / Layer 2 serving cell switching processing", "Layer 1 / Layer 2 serving cell switching", "Layer 1 / Layer 2 serving cell change processing", "Layer 1 / Layer 2 serving cell change", or "Layer 1 / Layer 2 handover", etc.

[0216] The "LTM candidate target identifier" may be rephrased as an "L1 / L2 candidate target index," "candidate target index," "LTM candidate configuration index," "L1 / L2 candidate configuration index," "candidate configuration index," "LTM target configuration ID," "L1 / L2 target configuration ID," "target configuration ID," "L1 / L2 candidate target configuration identifier," or "candidate target configuration identifier," etc. Furthermore, the LTM candidate target identifier may be an identifier indicated by an ltm-CandidateId information element, or may be an identifier indicated by another information element.

[0217] The "MAC CE that causes the terminal device to identify one or more cells that are targets of the serving cell" may be rephrased as "MAC CE that instructs a change of the serving cell to one or more target cells" or "MAC CE that changes one or more serving cells of the terminal device", etc. Furthermore, the MAC CE that causes the terminal device to identify one or more cells that are targets of the serving cell may be a MAC CE named an LTM Cell Switch Command MAC CE, or may be a MAC CE with another name.

[0218] Also, MAC CE may be referred to as Layer 2 signaling. Also, the above-mentioned measurements may be performed by Layer 1 (PHY layer) and / or Layer 3 (RRC layer). Also, the above-mentioned measurements may be reported by Layer 1 (PHY layer), Layer 2 (MAC layer), and / or Layer 3 (RRC layer).

[0219] 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. 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 the serving cell is changed to a target, another part of the information regarding the target may be notified to the terminal device by MAC CE. Information on the target of the serving cell is also referred to as a Layer 1 / Layer 2 inter-cell mobility candidate target configuration, an L1 / L2-triggered candidate target configuration, an L1 / L2 candidate target configuration, an LTM candidate target configuration, an LTM target configuration, or simply as a candidate target configuration. In the following description, to avoid confusion with a candidate target SpCell for conditional reconfiguration, information on the target of the serving cell is referred to as an LTM candidate target configuration. Furthermore, one or more LTM 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 LTM candidate target configurations notified from the base station device in a terminal device variable (UE variable).

[0220] To identify each of the one or more LTM candidate target configurations, for example, an LTM candidate target identifier associated with each LTM candidate target configuration may be notified to the terminal device. The terminal device may store the one or more LTM candidate target configurations notified from the base station device and the LTM candidate target identifier associated with the LTM candidate target configuration.

[0221] In Layer 1 / Layer 2 triggered mobility, some or all of the mobility scenarios (A) to (H) below may be supported, or other mobility scenarios may also be supported. Furthermore, the mobility scenario (F) below may be a scenario in which the target PCell and / or one or more target SCells are not the current serving cells. Additionally or alternatively, the mobility scenario (F) below may be a scenario in which the current PCell and SCell are swapped, i.e., the target PCell and SCell become the current SCell and PCell, respectively. (A) Intra-gNB-DU mobility (B) Inter-gNB-DU mobility within a base station aggregation unit (intra-gNB-CU inter-gNB-DU) mobility (C) Inter-frequency mobility (including mobility to an inter-frequency cell that is not the current serving cell) (D) PCell change in a terminal device that does not configure CA (E) PCell change without a change of one or more SCells in a terminal device that configures CA (F) PCell change with a change of one or more SCells in a terminal device that configures CA (G) PSCell change without the involvement of the MN in a terminal device that configures DC (H) Inter-cell beam management (not considered as a prerequisite for using Layer 1 / Layer 2 triggered mobility)

[0222] In Layer 1 / Layer 2 triggered mobility, the following principles (A) and / or (B) may be applied: (A) An LTM candidate target configuration may be provided as a delta configuration on top of a reference configuration. Note that the reference configuration is managed separately, and the terminal device maintains the reference configuration as a separate configuration. (B) The user plane communicates continuously, avoiding resets as much as possible, to avoid data loss and additional delays for data recovery. For example, security information is not updated in Layer 1 / Layer 2 triggered mobility. Additionally or alternatively, for example, successive Layer 1 / Layer 2 triggered mobility may be performed between multiple candidates without RRC reconfiguration. Note that successive Layer 1 / Layer 2 triggered mobility may refer to a procedure in which the terminal device does not release other LTM candidate target configurations after Layer 1 / Layer 2 triggered mobility is performed.

[0223] In Layer 1 / Layer 2 triggered mobility, some or all of the following (A) to (F) may be used for LTM candidate target configuration: (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

[0224] One or more LTM candidate target configurations may be notified to the terminal device by RRC signaling (e.g., a message related to RRC connection reconfiguration) or other control information (e.g., MAC CE, DCI). The terminal device may store the LTM candidate target configuration until it receives a MAC CE instructing a change of serving cell to one or more cells that are targets of the serving cell. The LTM candidate target configuration may be a complete LTM candidate cell configuration or a delta configuration that corresponds to a reference configuration. The complete LTM candidate cell configuration may be a configuration that includes all fields required to perform LTM processing. Furthermore, the LTM candidate target configuration may be common between intra-distributed unit mobility and inter-distributed unit mobility within an aggregation unit, or some of the LTM candidate target configurations may be different. The LTM candidate target configuration may include some or all of system information (searchSpaceSIB1, searchSpaceOtherSystemInformation, etc.), paging messages (pagingSearchSpace, etc.), and common search spaces (commonSearchSpaceList, etc.). Furthermore, security key updates may not be performed in Layer 1 / Layer 2 triggered mobility. Furthermore, the LTM candidate target configuration may be provided by an LTM-Config information element, or by an information element with another name. When the LTM candidate target configuration is a delta configuration corresponding to (with respect to) a reference configuration, it may be referred to as an LTM delta configuration, or an LTM candidate cell configuration, which will be described later.

[0225] Each of one or more cells associated with an LTM candidate target configuration is referred to as a "candidate cell," "candidate target cell," "LTM candidate cell," "LTM candidate target cell," or "LTM target cell." The LTM-Config information element described above may include a set of configurations related to one or more LTM candidate cells. Additionally or alternatively, the LTM-Config information element described above may include reference configurations (LTM Reference Configurations, described below) for one or more LTM candidate cells.

[0226] In the case of NR-DC, the LTM candidate target configuration (e.g., the LTM-Config information element described above) may be independent for the configuration associated with the MCG and the configuration associated with the SCG. In this case, the terminal device may receive two independent LTM candidate target configurations, i.e., two independent LTM-Config information elements, for each cell group. For example, the LTM-Config information element associated with the MCG may be included in a message related to RRC connection reconfiguration received using SRB1. Additionally or alternatively, for example, the LTM-Config information element associated with the SCG may be included in a message related to RRC connection reconfiguration received using SRB3 or embedded in a message related to RRC connection reconfiguration received using SRB1.

[0227] 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 RRC connection reconfiguration, or may use information elements that have new parameters added and / or some or all of the parameters deleted from those included in the message regarding RRC connection reconfiguration.

[0228] Each LTM candidate target configuration may be a message related to reconfiguration of an RRC connection. In this case, the LTM candidate target configuration may include at least a cell group configuration related to 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, the LTM candidate target configuration may include other information. For example, a cell group configuration related to an SCG may be included in the LTM candidate target configuration. For example, a measurement configuration may be included in the LTM candidate target configuration. For example, a radio bearer configuration may be included in the LTM candidate target configuration. In addition to one or more LTM candidate target configurations, an LTM candidate target identifier for identifying each LTM candidate target configuration may be notified from the base station device to the terminal device.

[0229] For example, the terminal device may receive a MAC CE from a base station device that identifies one or more cells that are targets of the serving cell, and based on the LTM candidate target identifier indicated by the MAC CE, apply a message regarding reconfiguration of the RRC connection, which is an LTM candidate target setting corresponding to the LTM candidate target identifier, to the RRC settings of the terminal device.

[0230] Additionally or alternatively, each LTM candidate target configuration may include an LTM reference configuration. The LTM reference configuration may be a common configuration for all LTM candidate cells configured by the terminal device in each LTM candidate target configuration. The LTM reference configuration may include a message related to RRC connection reconfiguration. The LTM reference configuration may be included in an LTM-Config information element. Additionally or alternatively, the LTM reference configuration may include at least a cell group configuration related to an MCG. The cell group configuration may include at least an SpCell configuration. The cell group configuration may include an SCell configuration. Additionally or alternatively, the LTM reference configuration may include other information. For example, a cell group configuration related to an SCG may be included in the LTM reference configuration. For example, a measurement configuration may be included in the LTM reference configuration. For example, a radio bearer configuration may be included in the LTM reference configuration. The LTM reference configuration may be a reference configuration with another name. The LTM reference configuration may be indicated by an ltm-referenceConfiguration information element or an information element with another name.

[0231] Additionally or alternatively, each LTM candidate target configuration may include an LTM candidate cell configuration (LTMCandidate Cell Configuration). The LTM candidate cell configuration may be a configuration associated with one or more of the LTM candidate cells configured by the terminal device in each LTM candidate target configuration. One LTM candidate target identifier may be associated with one LTM candidate cell configuration. The LTM candidate cell configuration may include a message related to RRC connection reconfiguration. The LTM candidate cell configuration may be included in an LTM-Config information element. Additionally or alternatively, the LTM candidate cell configuration may include at least a cell group configuration related to an MCG. The cell group configuration may include at least an SpCell configuration. The cell group configuration may also include an SCell configuration. Additionally or alternatively, the LTM candidate cell configuration may include other information. For example, a cell group configuration related to an SCG may be included in the LTM candidate cell configuration. For example, measurement configuration may be included in the LTM candidate cell configuration. For example, radio bearer configuration may be included in the LTM candidate cell configuration. Note that the LTM candidate cell configuration may be a reference configuration with another name. Furthermore, the LTM candidate cell configuration may be indicated by an LTM-Candidate information element, or may be indicated by an information element with another name. Furthermore, a message related to RRC connection reconfiguration included in the LTM candidate cell configuration may be indicated by an LTM-CandidateConfig information element, or may be indicated by an information element with another name. Furthermore, when a cell configured by a terminal device using the message related to RRC connection reconfiguration is an LTM candidate cell, the message related to RRC connection reconfiguration included in the LTM candidate cell configuration may include information required to execute an LTM cell switching procedure in which the LTM candidate cell is a target serving cell. The information required to execute the above-mentioned LTM cell switching procedure may be indicated by an ltm-CellSwitchInfo information element, etc.Additionally or alternatively, information required to perform the above-described LTM cell switch procedure may be included in a cell group configuration configured by the terminal device using the LTM candidate cell configuration. Additionally or alternatively, the terminal device may configure information required to perform the above-described LTM cell switch procedure outside of a synchronized reconfiguration information element. The information required to perform the above-described LTM cell switch procedure may include at least an RNTI value (e.g., a value indicated in a newUE-Identity information element). Additionally or alternatively, the information required to perform the above-described LTM cell switch procedure may include a ServingCellConfigCommon information element. Additionally or alternatively, the information required to perform the above-described LTM cell switch procedure may include a RACH-dedicated configuration (RACH-ConfigDedicated information element).

[0232] For example, the terminal device may receive a MAC CE from a base station device that identifies one or more cells that are targets of the serving cell, and based on an LTM candidate target identifier indicated by the MAC CE, apply a message regarding reconfiguration of the RRC connection included in the LTM candidate target configuration corresponding to the LTM candidate target identifier to an LTM reference configuration, thereby generating an LTM configuration of the terminal device (UE LTM configuration) and storing it in a variable of the terminal device (UE variable).

[0233] Additionally or alternatively, for example, based on receiving RRC signaling including an LTM candidate target configuration (e.g., an LTM-Config information element), the terminal device may generate a complete LTM candidate cell configuration by applying a message related to reconfiguration of an RRC connection (e.g., an LTM-CandidateConfig information element) included in the LTM candidate cell configuration corresponding to the LTM candidate target identifier (e.g., an ltm-CandidateId information element) to the apex of an LTM reference configuration (e.g., an ltm-referenceConfiguration information element) based on an LTM candidate target identifier (e.g., an ltm-CandidateId information element) associated with an LTM candidate cell configuration (e.g., an LTM-Candidate information element) included in the LTM candidate target configuration. Additionally or alternatively, if the LTM candidate cell configuration already exists in the terminal device's variables, the terminal device may replace the complete LTM candidate cell configuration. Additionally or alternatively, if the LTM candidate cell configuration does not exist in the terminal device's variables, the terminal device may store the LTM candidate cell configuration in the terminal device's variables. Additionally or alternatively, if the LTM candidate cell configuration includes an information element indicating a complete LTM candidate cell configuration (e.g., an ltm-ConfigComplete information element), the terminal device may consider a message regarding reconfiguration of an RRC connection included in the LTM candidate cell configuration as a complete LTM candidate cell configuration. Note that the variable held by the terminal device may be a variable named VarLTM-UE-Config or a variable with another name. Furthermore, the timing at which the terminal device generates a complete LTM candidate cell configuration may be postponed until the execution of an LTM cell switch.

[0234] In generating the above-mentioned complete LTM candidate cell configuration, when a message (LTM-CandidateConfig information element) related to the reconfiguration of the RRC connection included in the LTM candidate cell configuration is applied to the apex of the LTM reference configuration (ltm-referenceConfiguration information element), for example, the terminal device may perform some or all of (A) to (G) of the following process CMPLTM. Note that the Need N field is used for one-shot operation configuration by the terminal device (not held by the terminal device), and may be a field indicating that if nothing is contained (absent) when the message is received, the terminal device takes no action. Also, the Need R field is used for configuration held by the terminal device (not one-shot operation), and may be a field indicating that if nothing is contained (absent) when the message is received, the terminal device releases the current value. (Process CMPLTM) (A) The configuration included in the ltm-referenceConfiguration information element is considered as a complete LTM candidate cell configuration. (B) For each Need N field present in the LTM-CandidateConfig information element, when an element on the list is released, if present, the corresponding element is deleted from the complete LTM candidate cell configuration. (C) For each Need N field present in the LTM-CandidateConfig information element, when an element on the list is added or modified, if the corresponding element already exists in the complete LTM candidate cell configuration, modify it to the one in the received LTM-CandidateConfig information element; otherwise, add the corresponding element in the complete LTM candidate cell configuration according to the one in the LTM-CandidateConfig information element.(D) For each Need N field present in the LTM-CandidateConfig information element, if an element in the list is not released, added, or modified, if the field is present in the complete LTM candidate cell configuration, modify the corresponding Need N field to that in the received LTM-CandidateConfig information element; otherwise, add the Need N field received in the LTM-CandidateConfig information element to the complete LTM candidate cell configuration. (E) For each Need R field present in the LTM-CandidateConfig information element, if the field is present in the complete LTM candidate cell configuration, modify the corresponding Need R field to that in the received LTM-CandidateConfig information element; otherwise, add the Need R field received in the LTM-CandidateConfig information element to the complete LTM candidate cell configuration. (F) For each Need N field present in the LTM candidate cell configuration, if an element in the list is not released, added, or modified, and if the corresponding Need N field is not present in the LTM-CandidateConfig information element, remove the corresponding Need N field from the complete LTM candidate cell configuration. (G) For each Need R field present in the LTM candidate cell configuration, if the corresponding Need R field is not present in the LTM-CandidateConfig information element, remove the corresponding Need R field from the complete LTM candidate cell configuration.

[0235] Additionally or alternatively, the LTM candidate target configuration stored in the variable by the terminal device may include one or more entries. The entries may be referred to as "LTM candidate target entry," "candidate target entry," "LTM target entry," "target entry," or the like. Each LTM candidate target entry may include at least one entry identifier and one MCG cell group configuration. The entry identifier may be referred to as "LTM candidate target entry identifier," "candidate target entry identifier," "LTM target entry identifier," "target entry identifier," or the like. The entry identifier may be an identifier indicated by the ltm-CandidateId information element or an identifier indicated by another information element. Each LTM candidate target entry may optionally include one or more SCG cell group configurations, one or more radio bearer configurations, and / or one or more measurement configurations, as needed. A list containing one or more LTM candidate target entries may be referred to as an "LTM candidate target entry list information element," "LTM candidate target list information element," "candidate target entry list information element," "candidate target list information element," "LTM target entry list information element," "LTM target list information element," "target entry list information element," "target list information element," "LTM candidate target entry list," "candidate target entry list," "LTM target entry list," or "target entry list." The LTM candidate target entry list may be included in the LTM candidate target configuration. Also, if the LTM candidate target entry list held by the terminal device does not contain any entries, the terminal device may hold an empty list. The variable containing the LTM candidate target configuration held by the terminal device may be, for example, a variable named VarLTM-Config, or may have another name.The above-mentioned variable named VarLTM-Config may be composed of a variable indicating one LTM reference configuration (e.g., a variable indicated by an ltm-referenceConfiguration information element) and a list (LTM candidate target entry list) including one or more entries (e.g., entries indicated by an LTM-Candidate information element), or other variables or lists may be included in the above-mentioned variable named VarLTM-Config. Furthermore, the LTM candidate target entry list included in the above-mentioned variable named VarLTM-Config may be indicated by an ltm-CandidateList information element or may be indicated by an information element with another name. That is, the terminal device may hold two different variables: a variable for holding one LTM reference configuration and one or more LTM candidate cell configurations (e.g., a variable named VarLTM-Config), and a variable for holding the complete LTM candidate cell configuration generated above (e.g., a variable named VarLTM-UE-Config). Additionally or alternatively, for example, in the case of NR-DC, the terminal device may maintain two independent variables named VarLTM-Config associated with each of the above LTM-Config information elements. Additionally or alternatively, for example, in the case of NR-DC, the terminal device may maintain two independent variables named VarLTM-UE-Config associated with each of the above LTM-Config information elements.

[0236] Additionally or alternatively, the LTM candidate target configuration notified to the terminal device may include an add-modification (ToAddMod / ToRelease) structure. For example, the LTM candidate target configuration notified to the terminal device may include an add-modification list of LTM candidate target entries. Specifically, when each entry identifier (e.g., an LTM candidate target entry identifier) ​​included in the add-modification list of LTM candidate target entries exists in an entry of the LTM candidate target entry list held by the terminal device, the terminal device may perform some or all of the following processes (A) to (F). Note that in this specification, the "add-modification list of LTM candidate target entries" may be rephrased as an "add-modification list of candidate target entries," an "add-modification list of LTM target entries," an "add-modification list of target entries," or an "add-modification list of LTM candidate cells," etc. Note that the add-modification list of LTM candidate target entries may be indicated by an ltm-CandidateToAddModList information element or may be indicated by an information element with another name. (A) If an entry included in the addition modification list of an LTM candidate target entry contains an MCG cell group configuration, the MCG cell group configuration of the entry in the LTM candidate target entry list that matches the entry identifier associated with this entry (e.g., the ltm-CandidateId information element) is replaced with the MCG cell group configuration included in the addition modification list of the LTM candidate target entry. (B) If an entry included in the addition modification list of an LTM candidate target entry contains an SCG cell group configuration, the SCG cell group configuration of the entry in the LTM candidate target entry list that matches the entry identifier associated with this entry (e.g., the ltm-CandidateId information element) is replaced with the SCG cell group configuration included in the addition modification list of the LTM candidate target entry.(C) If an entry included in the additional modification list of an LTM candidate target entry includes a radio bearer configuration, the radio bearer configuration of the entry in the LTM candidate target entry list that matches the entry identifier associated with this entry (e.g., the ltm-CandidateId information element) is replaced with the radio bearer configuration included in the additional modification list of the LTM candidate target entry. (D) If an entry included in the additional modification list of an LTM candidate target entry includes a measurement configuration, the measurement configuration of the entry in the LTM candidate target entry list that matches the entry identifier associated with this entry (e.g., the ltm-CandidateId information element) is replaced with the measurement configuration included in the additional modification list of the LTM candidate target entry. (E) For each entry identifier (e.g., ltm-CandidateId information element) associated with an entry included in the addition / modification list of LTM candidate target entries, if the entry identifier matches an entry identifier associated with an entry (e.g., LTM-Candidate information element) included in the LTM candidate target entry list (e.g., ltm-CandidateList information element included in the VarLTM-Config information element) held by the terminal device, the entry held by the terminal device is replaced with the entry received in the addition / modification list of LTM candidate target entries. (F) For each entry identifier (e.g., ltm-CandidateId information element) associated with an entry included in the addition / modification list of LTM candidate target entries, if there is no entry included in the LTM candidate target entry list (e.g., ltm-CandidateList information element included in the VarLTM-Config information element) held by the terminal device that is associated with the entry identifier, the entry received in the addition / modification list of LTM candidate target entries is added to the LTM candidate target entry list held by the terminal device.

[0237] Additionally or alternatively, the LTM candidate target configuration notified to the terminal device may include a deletion list of LTM candidate target entries. For example, if the LTM candidate target configuration includes a deletion list of LTM candidate target entries, the terminal device may delete (remove) entries including identifiers specified in the deletion list of LTM candidate target entries from variables held by the terminal device. Note that the deletion list of LTM candidate target entries may be indicated by an ltm-CandidateToReleaseList information element or by an information element with another name.

[0238] Based on the above description, 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 description.

[0239] Fig. 5 is a block diagram showing the configuration of a terminal device (UE 122) in this embodiment. To avoid complicating the explanation, Fig. 5 shows only the main components closely related to this embodiment.

[0240] The UE 122 shown in FIG. 5 includes a receiver 500 that receives control information (such as DCI, MAC CE, and RRC signaling) 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 the control information (such as UCI and RRC signaling) to the base station device. The base station device 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, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processor 502 may include some or all of the physical layer processing section, MAC layer processing section, RLC layer processing section, PDCP layer processing section, SDAP layer processing section, RRC layer processing section, and NAS layer processing section. Additionally or alternatively, the receiver 500 may include some or all of the functionality of various layers (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, an SDAP layer, an RRC layer, and an NAS layer). That is, the receiver 500 may include some or all of a physical layer receiver, a MAC layer receiver, an RLC layer receiver, a PDCP layer receiver, an SDAP layer receiver, an RRC layer receiver, and an NAS layer receiver.

[0241] Fig. 6 is a block diagram showing the configuration of a base station device in this embodiment. To avoid complicating the explanation, Fig. 6 shows only main components closely related to this embodiment. The base station device may be the eNB 102 or the gNB 108.

[0242] The base station apparatus shown in FIG. 6 includes a transmitter 600 that transmits control information (such as DCI, MAC CE, and RRC signaling) to the UE 122, a processor 602 that creates control information (such as DCI and RRC signaling including parameters) and transmits it to the UE 122, causing the processor 502 of the UE 122 to process the information, and a receiver 604 that receives the control information (such as UCI and RRC signaling) from the UE 122. The processor 602 may include some or all of the functions of various layers (e.g., the 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 processing section, MAC layer processing section, RLC layer processing section, PDCP layer processing section, SDAP layer processing section, RRC layer processing section, and NAS layer processing section. Additionally or alternatively, the transmitter 600 may include some or all of the functionality 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 transmitter 600 may include some or all of a physical layer transmitter, a MAC layer transmitter, an RLC layer transmitter, a PDCP layer transmitter, an SDAP layer transmitter, an RRC layer transmitter, and a NAS layer transmitter.

[0243] An example of processing by the terminal device (UE 122) in this embodiment will be described with reference to Fig. 9. In this embodiment, the processing unit 502 of the UE 122 may include an RRC processing unit that performs RRC processing, an RLC processing unit that performs RLC processing, a MAC processing unit that performs MAC processing, and a PHY processing unit that performs PHY processing.

[0244] 9 is a diagram showing an example of processing by the UE 122 in this embodiment. The processing unit 502 of the UE 122 determines the conditions (step S900) and operates based on the determination (step S902).

[0245] The UE 122 receives RRC signaling from a base station device (gNB 108 and / or eNB 102). The RRC signaling may include one or more LTM candidate target configurations. The RRC processing unit of the UE 122 may store the one or more LTM candidate target configurations included in the RRC signaling in a terminal variable (VarLTM-Config). Additionally or alternatively, the RRC processing unit of the UE 122 may generate a complete LTM candidate cell configuration for the one or more LTM candidate target configurations included in the RRC signaling according to the above-described process CMPLTM and store the generated complete LTM candidate cell configuration in a terminal variable (VarLTM-UE-Config). Each of the LTM candidate target configurations may include an LTM reference configuration and one or more LTM candidate cell configurations. Additionally or alternatively, each of the LTM candidate cell configurations may be associated with an LTM candidate target identifier and / or one or more other identifiers. Additionally or alternatively, each of the LTM candidate target configurations may include one of a cell group configuration for an MCG or a cell group configuration for an SCG. That is, each of the LTM candidate cell configurations in the terminal variables held by the RRC processing unit of the UE 122 may include one SpCell configuration. In addition, each of the LTM candidate cell configurations in the terminal variables held by the RRC processing unit of the UE 122 may include one or more SCell configurations.

[0246] Additionally or alternatively, the RRC signaling may include an additional modification list of LTM candidate target entries. The RRC processing unit of UE 122 may store one or more entries included in the additional modification list of LTM candidate target entries as LTM candidate target entries in a terminal variable (VarLTM-Config). Additionally or alternatively, the RRC processing unit of UE 122 may generate a complete LTM candidate cell configuration for one or more entries included in the additional modification list of LTM candidate target entries according to the above-described process CMPLTM and store the generated complete LTM candidate cell configuration in a terminal variable (VarLTM-UE-Config). Each of the one or more entries included in the additional modification list of LTM candidate target entries may include an LTM reference configuration and one or more LTM candidate cell configurations. Additionally or alternatively, each of the LTM candidate cell configurations may be associated with an LTM candidate target entry identifier and / or one or more other identifiers. Additionally or alternatively, each of the LTM candidate target entries may include either a cell group configuration for an MCG or a cell group configuration for an SCG. That is, each of the LTM candidate cell configurations in the terminal variables held by the RRC processing unit of the UE 122 may include one SpCell configuration. Additionally, each of the LTM candidate cell configurations in the terminal variables held by the RRC processing unit of the UE 122 may include one or more SCell configurations.

[0247] The UE 122 may receive, from a base station device (gNB 108 and / or eNB 102), a MAC CE (hereinafter referred to as an LTM MAC CE, but may be a MAC CE with another name, such as the above-mentioned LTM cell switch command MAC CE) that identifies one or more target cells of a serving cell in a certain cell group. The MAC CE may include at least an identifier that identifies one of one or more LTM candidate cell configurations included in the RRC signaling. Additionally or alternatively, the MAC CE may include at least an identifier that identifies one of one or more LTM candidate cell configurations in a terminal variable (hereinafter referred to as VarLTM-UE-Config unless otherwise specified) held by an RRC processing unit of the UE 122. Additionally or alternatively, the identifier that identifies the one LTM candidate cell configuration included in the MAC CE may be an LTM candidate target identifier, an LTM candidate target entry identifier, or another identifier. In the following description, the MAC processing unit of the UE 122 may be the MAC processing unit of this cell group unless otherwise specified.

[0248] In step S900, the MAC processing unit of the UE 122 that has received the LTM MAC CE determines whether the following condition (a) is satisfied: (a) The LTM MAC CE includes an identifier (first identifier) ​​that identifies the LTM candidate cell configuration.

[0249] For example, the first identifier may be an LTM candidate target identifier. Alternatively, for example, the first identifier may be an LTM candidate target entry identifier. Additionally or alternatively, for example, the first identifier may be an identifier indicated in an ltm-CandidateId information element.

[0250] If the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied, it may indicate to a higher layer (such as an RRC processing unit of UE 122) in step S902 that the LTM MAC CE has been received. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied, it may indicate to a higher layer (such as an RRC processing unit of UE 122) in step S902 that an LTM cell switching procedure is to be triggered. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied, it may notify a higher layer (such as an RRC processing unit of UE 122) of the first identifier included in the LTM MAC CE in step S902.

[0251] An example of processing will be described when the MAC processing unit of UE 122 notifies a higher layer (such as an RRC processing unit of UE 122) of the start or skip of a random access procedure. When the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a first value, the MAC processing unit of UE 122 determines in step S902 that a random access procedure for the LTM cell switching process needs to be triggered, and may additionally or instead notify a higher layer (such as an RRC processing unit of UE 122) of the start of a random access procedure for the LTM cell switching process triggered based on reception of the LTM MAC CE. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the Timing Advance Command field notified in the LTM MAC CE is set to a second value different from the first value, it may determine in step S902 that the timing advance of the serving cell (source SpCell) is valid. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the Timing Advance Command field notified in the LTM MAC CE is set to a second value different from the first value, it may apply the same N_TA value as that of the serving cell as the N_TA value of one or more LTM candidate cells associated with the LTM candidate cell configuration described in the condition (a).Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, then in step S902, the MAC processing unit of UE 122 may apply the latest N_TA value of the TAG (PTAG, STAG, etc.) of the serving cell as the N_TA value of one or more LTM candidate cells associated with the LTM candidate cell configuration described in condition (a). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, the MAC processing unit of UE 122 may indicate to a higher layer (such as an RRC processing unit of UE 122) in step S902 that a random access procedure for an LTM cell switch procedure triggered based on reception of the LTM MAC CE is skipped. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, the MAC processing unit of UE 122 may trigger contention-based random access (CBRA) to the LTM candidate cell upon receiving an RRC reconfiguration complete message (described later) from a higher layer (such as an RRC processing unit of UE 122). Alternatively, in step S902, the MAC processing unit of the UE 122 may notify a higher layer (such as the RRC processing unit of the UE 122) of triggering contention-based random access (CBRA) to the LTM candidate cell.Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field signaled in the LTM MAC CE is set to a value other than the first value or the second value, it may process a timing advance command using the value of the timing advance command field in step S902. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field signaled in the LTM MAC CE is set to a value other than the first value or the second value, it may set an N_TA value using the value of the timing advance command field in step S902, and additionally or alternatively apply the set N_TA value as the N_TA value of the PTAG of one or more LTM candidate cells associated with the LTM candidate cell configuration described in the condition (a). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a value other than the first value or the second value, then in step S902, the MAC processing unit of UE 122 may indicate to a higher layer (such as an RRC processing unit of UE 122) to skip a random access procedure for an LTM cell switching process triggered based on reception of the LTM MAC CE.Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a value other than the first value or the second value, then, based on the determination that the value indicated in the timing advance command field is set to a third value (FFD, etc.), in step S902, upon receiving an RRC reconfiguration complete message (described below) from a higher layer (such as an RRC processing unit of UE 122), the MAC processing unit of UE 122 may notify the higher layer (such as an RRC processing unit of UE 122) of the triggering of contention-based random access (CBRA) for the LTM candidate cell. Alternatively, in step S902, the MAC processing unit of UE 122 may notify the higher layer (such as an RRC processing unit of UE 122) of the triggering of contention-based random access (CBRA) for the LTM candidate cell.

[0252] An example of processing will be described below when the MAC processing unit of UE 122 does not notify higher layers (such as the RRC processing unit of UE 122) of the start or skip of a random access procedure. When the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a first value, the MAC processing unit of UE 122 determines in step S902 that a random access procedure for the LTM cell switch procedure needs to be triggered, and may additionally or instead start the random access procedure for the LTM cell switch procedure triggered based on reception of the LTM MAC CE when an RRC reconfiguration complete message described below is received from higher layers (such as the RRC processing unit of UE 122). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, it may determine in step S902 that the timing advance of the serving cell (source SpCell) is valid. Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, it may apply the same N_TA value as that of the serving cell as the N_TA value of an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration described in the condition (a).Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, then in step S902, the MAC processing unit of UE 122 may apply the latest N_TA value of the TAG (PTAG, STAG, etc.) of the serving cell as the N_TA value of an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration described in condition (a). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a second value different from the first value, then in step S902, the MAC processing unit of UE 122 may trigger a contention-based random access (CBRA) to the LTM candidate cell upon receiving an RRC reconfiguration complete message (described below) from a higher layer (such as an RRC processing unit of UE 122). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a value other than the first value or the second value, then in step S902, the MAC processing unit of UE 122 may process a timing advance command using the value of the timing advance command field.Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and the value indicated in the timing advance command field notified in the LTM MAC CE is set to a value other than the first value or the second value, then in step S902, it may set an N_TA value using the value of the timing advance command field, and additionally or alternatively apply the set N_TA value as the N_TA value of the PTAG of one or more LTM candidate cells associated with the LTM candidate cell configuration described in condition (a). Additionally or alternatively, if the MAC processing unit of UE 122 determines in step S900 that the condition (a) is satisfied and that the value indicated in the timing advance command field notified in the LTM MAC CE is set to a value other than the first value or the second value, then based on the determination that the value indicated in the timing advance command field is set to a third value (FFD, etc.), in step S902, when an RRC reconfiguration complete message described below is received from a higher layer (such as the RRC processing unit of UE 122), the MAC processing unit of UE 122 may trigger a contention-based random access (CBRA) to the LTM candidate cell.

[0253] The timing advance command field may indicate whether the timing advance of an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration associated with the first identifier is valid. That is, when the value indicated in the timing advance command field is set to FFF, the field may indicate that no valid timing adjustment for the PTAG of the LTM candidate cell is available, and may also indicate that UE 122 performs a random access procedure to the LTM candidate cell. In this case, for example, the MAC processing unit of UE 122 may determine that the timing advance of the SpCell is not valid. Additionally or alternatively, if the value indicated in the Timing Advance Command field is set to a value other than FFF, the field may indicate an index value used to control the amount of timing adjustment applied by the MAC processing unit of the UE 122, and may also indicate that the UE 122 can skip the random access procedure for the LTM candidate cell. In this case, for example, the MAC processing unit of the UE 122 may determine that the timing advance of the SpCell is valid and, additionally or alternatively, notify the RRC processing unit of the UE 122 that the timing advance of the SpCell is valid. Additionally or alternatively, the Timing Advance Command field may indicate a value (index value) from 0 to 3846, for example. The MAC processing unit of the UE 122 may set the value of the N_TA using the value of the Timing Advance Command field. The first value may be, for example, FFF, or another value. Additionally or alternatively, the second value may be FFE or some other value.Additionally or alternatively, the second value may be different when the MAC processing unit of UE 122 applies the latest N_TA value of the PTAG of the serving cell, when the MAC processing unit of UE 122 applies the latest N_TA value of the STAG of the serving cell, and / or when the MAC processing unit of UE 122 applies the latest N_TA value of the other TAGs of the serving cell. Additionally or alternatively, the above-mentioned "one or more LTM candidate cells associated with the LTM candidate cell configuration" may be rephrased as "indicated LTM target cell" or "indicated LTM target configuration," etc. Additionally or alternatively, the one or more LTM candidate cells associated with the above-mentioned LTM candidate cell configuration may include at least SpCells, or alternatively, may be composed only of cells other than SpCells.

[0254] An example of processing related to the time alignment timer (timeAlignmentTimer) in step S902 will be described. When the MAC processing unit of UE 122 processes the timing advance command in step S902 or sets the N_TA value using the value in the timing advance command field in step S902, the MAC processing unit may start a time alignment timer (timeAlignmentTimer) associated with the PTAG of the indicated LTM target cell, or restart it if it is already running. Additionally or alternatively, when the MAC processing unit of UE 122 applies the same N_TA value as that of the serving cell in step S902 or applies the latest N_TA value of the TAG of the serving cell in step S902, the MAC processing unit may start a time alignment timer (timeAlignmentTimer) associated with the corresponding TAG of the indicated LTM target cell.

[0255] The RRC processing unit of UE 122 that holds the LTM candidate target configuration or the LTM candidate target entry in a terminal variable may trigger an LTM cell switching process based on some or all of the following information or instructions (b) to (d) that are notified or instructed from a lower layer (such as a MAC processing unit of UE 122): In addition to or instead of this, the RRC processing unit of UE 122 that holds the LTM candidate target configuration or the LTM candidate target entry in a terminal variable may select an LTM candidate cell configuration associated with the first identifier from one or more LTM candidate cell configurations held in the terminal variable based on some or all of the following information or instructions (b) to (d) that are notified or instructed from a lower layer (such as a MAC processing unit of UE 122): Additionally or alternatively, the RRC processing unit of UE 122 that holds the LTM candidate target configuration or the LTM candidate target entry in a terminal variable may initiate an RRC reconfiguration procedure during the LTM cell switch process, based on some or all of the following information or instructions (b) to (d) that are notified or instructed from a lower layer (such as a MAC processing unit of UE 122): Additionally or alternatively, the RRC processing unit of UE 122 that holds the LTM candidate target configuration or the LTM candidate target entry in a terminal variable may apply the selected LTM candidate cell configuration according to the RRC reconfiguration procedure initiated during the LTM cell switch process, based on some or all of the following information or instructions (b) to (d) that are notified or instructed from a lower layer (such as a MAC processing unit of UE 122): For example, the RRC processing unit of UE 122 may initiate the RRC reconfiguration procedure after resetting a MAC entity of the cell group during the LTM cell switch process: Additionally or alternatively, for example, the RRC processing unit of UE 122 may initiate the RRC reconfiguration procedure before submitting an RRC reconfiguration complete message to the lower layers (PHY, MAC, etc.) of UE 122 during the LTM cell switching process.Additionally or alternatively, the RRC processing unit of UE 122 may initiate an RRC reconfiguration procedure during the LTM cell switch process at a timing other than that described in the above example. In this embodiment, the RRC processing unit of UE 122 may submit an RRC reconfiguration complete message to a lower layer (PHY, MAC, etc.) of UE 122 during the RRC reconfiguration procedure, or alternatively, may submit an RRC reconfiguration complete message to a lower layer (PHY, MAC, etc.) of UE 122 after the RRC reconfiguration procedure. (b) The LTM MAC CE has been received. (c) The LTM cell switch process is triggered. (d) The first identifier included in the LTM MAC CE.

[0256] In step S900, the RRC processing unit of UE 122 initiating the RRC reconfiguration procedure determines whether each of the following conditions (e) to (m) is satisfied: (e) The RRC reconfiguration procedure is initiated by an LTM cell switch procedure; (f) The RRC reconfiguration procedure is initiated within the LTM cell switch procedure; (g) A lower layer (such as a MAC processing unit of UE 122) notifies the initiation of a random access procedure for the LTM cell switch procedure; (h) A lower layer (such as a MAC processing unit of UE 122) has notified the initiation of a random access procedure for the LTM cell switch procedure; (i) A lower layer (such as a MAC processing unit of UE 122) notifies the skipping of the random access procedure for the LTM cell switch procedure; (j) A lower layer (such as a MAC processing unit of UE 122) has notified the skipping of the random access procedure for the LTM cell switch procedure; (k) There is no need to trigger the random access procedure for the LTM cell switch procedure. (l) A lower layer (such as a MAC processing unit of UE 122) notifies the LTM candidate cell that it will trigger contention-based random access (CBRA). (m) A lower layer (such as a MAC processing unit of UE 122) notifies the LTM candidate cell that it will trigger contention-based random access (CBRA).

[0257] For example, whether the above-mentioned condition (k) is satisfied may be determined based on whether the timing advance of an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration linked to the first identifier is valid and / or whether the validity of the timing advance of the SpCell has been notified from a lower layer (such as a MAC processing unit of UE 122) at the time when the RRC processing unit of UE 122 submits an RRC reconfiguration complete message to a lower layer (such as a PHY, MAC, or RLC) of UE 122 during the LTM cell switching process. Note that whether the timing advance of the SpCell is valid may be determined based on, for example, whether the N_TA of the TAG including the SpCell is maintained. Additionally or alternatively, for example, whether the above-mentioned condition (k) is satisfied may be determined based on whether the LTM candidate cell configuration associated with the first identifier, which is held in the terminal variable by the RRC processing unit of UE 122, includes information indicating that it is not necessary to trigger a random access procedure for the LTM cell switching process.

[0258] Note that "starting a random access procedure for the LTM cell switching process" described in the above (g) and (h) may be rephrased as "triggering a random access procedure for the LTM cell switching process" or "needing to trigger a random access procedure for the LTM cell switching process", etc. Also, "skipping the random access procedure for the LTM cell switching process" described in the above (i) and (j) may be rephrased as "not needing to trigger a random access procedure for the LTM cell switching process", etc.

[0259] If the RRC processing unit of UE 122 determines in step S900 that some or all of the conditions (e) to (f) are satisfied, it may submit in step S902 an RRC reconfiguration complete message to lower layers (PHY, MAC, RLC, etc.) of UE 122. Alternatively, if the RRC processing unit of UE 122 determines in step S900 that some or all of the conditions (e) to (f) and some or all of the conditions (g) to (h) are satisfied, or if it determines that some or all of the conditions (e) to (f) are satisfied and none of the conditions (i) to (k) are satisfied, it may initiate the random access procedure in an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration linked to the first identifier, after submitting the RRC reconfiguration complete message to lower layers (PHY, MAC, RLC, etc.) of UE 122. Additionally or alternatively, if the RRC processing unit of UE122 determines in step S900 that some or all of the conditions (e) to (f) and some or all of the conditions (l) to (m) are satisfied, or if it determines that some or all of the conditions (e) to (f) are satisfied and none of the conditions (i) to (k) are satisfied, then in step S902, it may submit an RRC reconfiguration complete message to the lower layers (PHY, MAC, RLC, etc.) of UE122, and then trigger the contention-based random access (CBRA) in an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration linked to the first identifier.Additionally or alternatively, if the RRC processing unit of UE122 determines in step S900 that some or all of the conditions (e) to (f) and some or all of the conditions (i) to (k) are satisfied, or if it determines that some or all of the conditions (e) to (f) are satisfied and none of the conditions (g), (h), (l) and (m) are satisfied, then in step S902, after submitting an RRC reconfiguration complete message to the lower layers (PHY, MAC, RLC, etc.) of UE122, it does not need to initiate the random access procedure in an SpCell among one or more LTM candidate cells associated with the LTM candidate cell configuration linked to the first identifier.

[0260] Note that in this embodiment, processing a timing advance command may, for example, apply a timing advance command (TAC) for the PTAG of one or more LTM candidate cells (indicated LTM target cells) associated with the LTM candidate cell configuration linked to a first identifier included in the LTM MAC CE. Additionally or alternatively, in this embodiment, processing a timing advance command may, for example, set an N_TA value using a value of a timing advance command field notified in the LTM MAC CE. Additionally or alternatively, in this embodiment, processing a timing advance command may, for example, apply the set N_TA value as the N_TA value of the indicated LTM target cell. Additionally or alternatively, in this embodiment, processing a timing advance command may, for example, start or restart a time adjustment timer associated with the PTAG. Additionally or alternatively, in this embodiment, expressions such as "timing adjustment," "timing advance," and "time alignment" may be interchangeable. Additionally or alternatively, in the above description, "PTAG of an indicated LTM target cell" may be interchangeable with "PTAG of an indicated LTM target setting" or simply "PTAG," etc. Additionally or alternatively, in the above description, "a value indicated in a timing advance command field" may be interchangeable with "the value of N_TA" or "a timing advance command with the value," etc.

[0261] The above-described embodiments may be combined with each other. Furthermore, in the above-described embodiments, applying an LTM candidate cell configuration may mean performing an RRC reconfiguration procedure using a message related to reconfiguration of an RRC connection included in the LTM candidate cell configuration. Furthermore, in the above-described embodiments, an SpCell among one or more LTM candidate cells associated with an LTM candidate cell configuration linked to the first identifier may be one SpCell configured by a terminal device using a cell group configuration included in the LTM candidate cell configuration. Additionally or alternatively, in the above-described embodiments, expressions such as "an SpCell among one or more LTM candidate cells associated with an LTM candidate cell configuration linked to the first identifier," "an SpCell configured by a terminal device using an LTM candidate cell configuration linked to the first identifier," and "a target SpCell" may be interchangeable. Furthermore, in the above-described embodiments, "initiate" and "trigger" may be interchangeable. Additionally or alternatively, the RRC reconfiguration procedure in each of the above-described embodiments may be performed independently in each cell group in the case of NR-DC. For example, if an LTM candidate cell configuration identified by an identifier included in the LTM MAC CE in each of the above-described embodiments is included in an LTM candidate target configuration associated with an MCG (e.g., the above-described LTM-Config information element), the RRC processing unit of UE 122 may perform the RRC reconfiguration procedure in the MCG but not in the SCG.

[0262] This allows for efficient configuration of the target cell when performing Layer 1 / Layer 2 Triggered Mobility (LTM).

[0263] In the above description, once a timer is started, it continues to run until it is stopped or expires. Once a timer expires, it may be considered to be no longer running (stopped). A timer always starts (if the timer is stopped) or restarts (if the timer is running) from its initial value. The period from when a timer is started or restarted to when it expires is not updated until the timer is stopped or expires. 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 a timer is started or restarted to when it expires. Additionally or alternatively, the MAC entity of the terminal device may use a pre-defined default value as the period from when a timer is started or restarted to when it expires. If the MAC entity of the terminal device sets the period from when a 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.

[0264] Furthermore, unless otherwise specified, the radio bearer in the above description may be a DRB, an SRB, or a combination of a DRB and an SRB.

[0265] In the above description, the terms "user plane," "user plane protocol," "user plane interface," etc. may be interchangeable.

[0266] Also, 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."

[0267] In the above description, expressions such as "variables of the terminal device," "terminal variables," and "variables" may be interchangeable.

[0268] Furthermore, unless otherwise specified, the serving cell change in the above description may refer to a Layer 1 / Layer 2 serving cell change.

[0269] Also, in the above description, terms such as "provided," "signaled," and "selected" may be used interchangeably.

[0270] In the above description, expressions such as "LTM candidate target identifier" and "LTM candidate target entry identifier" may be interchangeable.

[0271] In the above description, expressions such as "notified" and "indicated" may be interchangeable.

[0272] In the above description, expressions such as "link," "associate," and "link" may be interchangeable.

[0273] In addition, in the above description, expressions such as "included," "included," and "was included" may be used interchangeably.

[0274] In the above description, "the above-mentioned" may be replaced with "the above-mentioned."

[0275] In the above description, expressions such as "confirmed to be...", "is set to...", and "includes..." may be interchangeable.

[0276] Furthermore, in each example of processing or each example of processing flow in the above description, some or all of the steps may not be executed. Furthermore, in each example of processing or each example of processing flow in the above description, the order of the steps may be different. Furthermore, in each example of processing or each example of processing flow in the above description, some or all of the processing within each step may not be executed. Furthermore, in each example of processing or each example of processing flow 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."

[0277] 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".

[0278] In the above explanation, if the conditions "A" and "B" are contradictory conditions, the condition "B" may be expressed as the "other" condition of the condition "A."

[0279] The program that runs on the device according to this embodiment may be a program that controls a central processing unit (CPU) or the like to make a computer function so as to realize the functions of this embodiment. The program or the information handled by the program is temporarily loaded into a volatile memory such as a random access memory (RAM) during processing, or stored in a nonvolatile memory such as a flash memory or a hard disk drive (HDD), and is read, modified, and written by the CPU as needed.

[0280] Note that a part of the device in the above-described embodiment may be realized by a computer. In this case, a program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. The "computer system" here refers to a computer system built into the device, including hardware such as an operating system and peripheral devices. Furthermore, the "computer-readable recording medium" may be any of a semiconductor recording medium, an optical recording medium, a magnetic recording medium, etc.

[0281] Furthermore, the term "computer-readable recording medium" may also include a medium that dynamically stores 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 a medium that stores a program for a certain period of time, such as a volatile memory within a computer system that serves as a server or client in such cases. The program may also be one that realizes part of the above-mentioned functions, or one that can realize the above-mentioned functions in combination with a program already stored in the computer system.

[0282] Furthermore, each functional block or feature of the device used in the above-described embodiments may be implemented or performed by an electrical circuit, typically an integrated circuit or multiple integrated circuits. The electrical circuit designed to perform 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 advances in semiconductor technology result in the emergence of integrated circuit technology that replaces current integrated circuits, integrated circuits based on that technology may also be used.

[0283] It should be noted that the present embodiment is not limited to the above-described embodiment. In the embodiment, an example of a device is described, but the present 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.

[0284] Although this embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment and includes design modifications within the scope of the gist of this embodiment. 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. Furthermore, configurations in which elements described in the above embodiment are substituted with elements that achieve the same effect are also included.

[0285] 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.

[0286] 100 E-UTRA 102 eNB 104 EPC 106 NR 108 gNB 110 5GC 112, 114, 116, 118, 120, 124 Interface 122 UE 200, 300 PHY 202, 302 MAC 204, 304 RLC 206, 306 PDCP 208, 308 RRC 310 SDAP 210, 312 NAS 500, 604 Receiver 502, 602 Processor 504, 600 Transmitter

Claims

1. A terminal device that communicates with a base station device using a serving cell, comprising: an RRC receiving unit that receives RRC signaling including an LTM candidate target configuration from the base station device; an RRC processing unit that holds the LTM candidate target configuration in a terminal variable; a MAC receiving unit that receives a MAC CE from the base station device; and a MAC processing unit, wherein the LTM candidate target configuration includes at least one or more LTM candidate cell configurations, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, the MAC CE including a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, wherein the first field is a timing advance command field indicating whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid, and the MAC processing unit, based on receiving the MAC CE, instructs the RRC processing unit to: trigger an LTM cell switching process, and notifying the first LTM candidate target identifier, the MAC processing unit: determines, based on the value indicated in the first field being set to a first value, that it is necessary to trigger a random access procedure for the LTM cell switching process; applies, based on the value indicated in the first field being set to a second value different from the first value, a latest N_TA value of the TAG of the serving cell as a value of N_TA of the SpCell; sets, based on the value indicated in the first field being set to a value other than the first value or the second value, a value of N_TA using the value of the first field; and applies the N_TA value as a value of timing advance of the SpCell; the RRC processing unit: triggers an LTM cell switching process based on the information notified from the MAC processing unit; selects the first LTM candidate cell configuration from the one or more LTM candidate cell configurations;A terminal device which starts an RRC reconfiguration procedure in the LTM cell switching process, and applies the selected first LTM candidate cell configuration according to the RRC reconfiguration procedure.

2. A method of a terminal device communicating with a base station device using a serving cell, comprising: a step of receiving RRC signaling including an LTM candidate target configuration from the base station device; a step of retaining the LTM candidate target configuration in a terminal variable; and a step of receiving a MAC CE from the base station device, wherein the LTM candidate target configuration includes at least one or more LTM candidate cell configurations, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, and the MAC CE includes a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, wherein the first field is a timing advance command field indicating whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid, and the method of the terminal device comprises: based on receiving the MAC CE, in an RRC layer of the terminal device, a trigger of an LTM cell switching process, and notifying the first LTM candidate target identifier; determining that it is necessary to trigger a random access procedure for the LTM cell switching process, based on the value indicated in the first field being set to a first value; applying the latest N_TA value of the TAG of the serving cell as the N_TA value of the SpCell, based on the value indicated in the first field being set to a second value different from the first value; setting the N_TA value using the value of the first field, based on the value indicated in the first field being set to a value other than the first value or the second value, and applying the N_TA value as the timing advance value of the SpCell; triggering an LTM cell switching process, based on information notified from the MAC layer of the terminal device; and selecting the first LTM candidate cell configuration from the one or more LTM candidate cell configurations.The method includes: initiating an RRC reconfiguration procedure in the LTM cell switching process; and applying the selected first LTM candidate cell configuration according to the RRC reconfiguration procedure.

3. An integrated circuit implemented in a terminal device that communicates with a base station device using a serving cell, comprising: a function for receiving RRC signaling including an LTM candidate target configuration from the base station device; a function for retaining the LTM candidate target configuration in a terminal variable; and a function for receiving a MAC CE from the base station device, wherein the LTM candidate target configuration includes at least one or more LTM candidate cell configurations, each of the LTM candidate cell configurations being associated with one LTM candidate target identifier, and the MAC CE includes a first LTM candidate target identifier that identifies a first LTM candidate cell configuration that is one of the one or more LTM candidate cell configurations, and a first field, wherein the first field is a timing advance command field indicating whether a timing advance of an SpCell of one or more LTM candidate cells associated with the first LTM candidate cell configuration is valid, and the integrated circuit, based on receiving the MAC CE, transmits to an RRC layer of the terminal device a trigger for an LTM cell switching process, and a function for notifying the first LTM candidate target identifier; a function for determining that it is necessary to trigger a random access procedure for the LTM cell switching process, based on the value indicated in the first field being set to a first value; a function for applying the latest N_TA value of the TAG of the serving cell as the N_TA value of the SpCell, based on the value indicated in the first field being set to a second value different from the first value; a function for setting the N_TA value using the value of the first field, based on the value indicated in the first field being set to a value other than the first value or the second value, and applying the N_TA value as the timing advance value of the SpCell; a function for triggering an LTM cell switching process, based on information notified from a MAC layer of the terminal device; and a function for selecting the first LTM candidate cell configuration from the one or more LTM candidate cell configurations.an integrated circuit configured to: initiate an RRC reconfiguration procedure in the LTM cell switching process; and apply the selected first LTM candidate cell configuration in accordance with the RRC reconfiguration procedure.

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