Terminal device, base station device, and method

Abstract

This terminal device that communicates with a base station device receives RRC signaling from the base station device, receives, from the base station device, Medium Access Control (MAC) signaling including information for identifying one LTM candidate information element and information for identifying a Timing Advance (TA) value associated with the one LTM candidate information element, and starts a synchronization timer associated with the one LTM candidate information element on the basis of the fact that the MAC signaling has been received. Further, on the basis of a determination that the condition associated with the one LTM candidate information element has been satisfied, the terminal device: (a) applies the TA value associated with the one LTM candidate information element as the TA value of a PTAG; (b) applies the synchronization timer value associated with the one LTM candidate information element as the value of the TA timer; and (c) starts the TA timer.

Description

Terminal device, base station device, and method

[0001] The present invention relates to a terminal device, a base station device, and a method. This application claims priority to Japanese Patent Application No. 2024-221634, filed in Japan on December 18, 2024, the content of which is incorporated herein by reference.

[0002] In the 3rd Generation Partnership Project (3GPP (registered trademark)), which is a standardization project for cellular mobile communication systems, technical studies and standard setting for cellular mobile communication systems, including radio access, core network, services, etc., are being conducted.

[0003] For example, in 3GPP, E-UTRA (Evolved Universal Terrestrial Radio Access) was started for technical studies and standard setting as a radio access technology (RAT) for cellular mobile communication systems for the 3.9th and 4th generations. Even now, in 3GPP, technical studies and standard setting for extended technologies of E-UTRA are being conducted. Note that E-UTRA is also referred to as Long Term Evolution (LTE (registered trademark)), and extended technologies may also be referred to as LTE-Advanced (LTE-A) and LTE-Advanced Pro (LTE-A Pro).

[0004] Also, in 3GPP, NR (New Radio, or NR Radio access) was started for technical studies and standard setting as a radio access technology (RAT) for cellular mobile communication systems for the 5th generation (5G). Even now, in 3GPP, technical studies and standard setting for extended technologies of NR are being conducted.

[0005] 3GPP TS 38.300 v18.1.0,"NR;NR and NG-RAN Overall description; Stage 2" pp98-1013GPP TS 38.331 v18.1.0,"NR;Radio Resource Control (RRC);Protocol specifications" p35 pp159-163 pp794-800 p15023GPP TS 38.321 v18.1.0, "NR;Medium Access Control (MAC) protocol specification" p135 pp284-2853GPP TS 38.213 v18.3.0, "NR;Physical layer procedures for control" pp12-14

[0006] As an extension of NR, there is a serving cell change technology that allows terminal devices to move from the coverage area of ​​one cell to the coverage area of ​​another. This serving cell change is triggered by Layer 3 (also called RRC) measurement, and synchronized reconfiguration for the serving cell change is triggered by RRC signaling. Compared to RRC signaling, Layer 1 or Layer 2 signaling has the advantage of low latency and low overhead. Therefore, a serving cell change technology triggered by Layer 1 or Layer 2 signaling (Layer 1 / Layer 2 mobility optimization (L1 / L2 mobility enhancement) technology) has been specified. To further enhance the robustness of this technology, consideration of conditional L1 / L2 mobility enhancement technology has been initiated.

[0007] One aspect of the present invention has been made in view of the above circumstances, and one of its objectives is to provide a terminal device, a base station device, a communication method, and an integrated circuit that can efficiently perform communication control.

[0008] To achieve the above objective, one aspect of the present invention employs the following means. In other words, one aspect of the present invention is a terminal device that communicates with a base station device, comprising a receiving unit that receives RRC (Radio Resource Control) signaling from the base station device, and a processing unit, wherein the RRC signaling includes one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements, the receiving unit receives MAC (Medium Access Control) signaling from the base station device which includes information identifying one LTM candidate information element and information identifying the value of TA (Timing Advance) associated with the one LTM candidate information element, and the processing unit, based on the receipt of the MAC signaling, starts a synchronization timer associated with the one LTM candidate information element, and, based on the determination that the conditions associated with the one LTM candidate information element have been met, (a) applies the value of the TA associated with the one LTM candidate information element as the value of TA in the PTAG, (b) applies the value of the synchronization timer associated with the one LTM candidate information element as the value of the TA timer, and (c) starts the TA timer.

[0009] Another aspect of the present invention is a base station device that communicates with a terminal device, comprising a transmitting unit that transmits RRC (Radio Resource Control) signaling to the terminal device, and a processing unit, wherein the processing unit includes in the RRC signaling one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements, and by applying the RRC signaling to the terminal device, the terminal device receives MAC (Medium Access) information including information identifying one LTM candidate information element and information identifying the TA (Timing Advance) value associated with the one LTM candidate information element. The system receives a Control signaling from the base station device, starts the synchronization timer associated with one LTM candidate information element based on the reception of the MAC signaling, and, based on the determination that one of the conditions associated with one LTM candidate information element has been met, (a) applies the value of the TA associated with one LTM candidate information element as the value of the TA of the PTAG, (b) applies the value of the timer associated with one LTM candidate information element as the value of the TA timer, and (c) starts the TA timer.

[0010] Another aspect of the present invention is a method for a terminal device to communicate with a base station device, comprising the steps of: receiving an RRC (Radio Resource Control) signaling from the base station device; receiving a MAC (Medium Access Control) signaling from the base station device, wherein the RRC signaling includes one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements, and including information identifying one LTM candidate information element and information identifying the value of TA (Timing Advance) associated with one LTM candidate information element; and the processing unit starting a synchronization timer associated with one LTM candidate information element based on the receipt of the MAC signaling, and determining that the conditions associated with one LTM candidate information element have been met, (a) applying the value of the TA associated with one LTM candidate information element as the value of TA in the PTAG; (b) applying the value of the synchronization timer associated with one LTM candidate information element as the value of the TA timer; and (c) starting the TA timer.

[0011] These comprehensive or specific embodiments may be implemented as systems, devices, methods, integrated circuits, computer programs, or recording media, or as any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

[0012] According to one aspect of the present invention, terminal equipment, base station equipment, and methods can achieve efficient communication control processing.

[0013] A schematic diagram of the communication system according to this embodiment. A diagram of an example of the E-UTRA protocol configuration according to this embodiment. A diagram of an example of the NR protocol configuration according to this embodiment. A diagram showing an example of the procedure flow for various settings in RRC according to this embodiment. A block diagram showing the configuration of the terminal device in this embodiment. A block diagram showing the configuration of the base station device in this embodiment. An example of the ASN.1 description included in the message regarding the reconfiguration of the RRC connection in NR in this embodiment. An example of the ASN.1 description representing the fields and / or information elements related to the ServingCellConfigCommon information element in this embodiment. An example of the processing of the terminal device in this embodiment.

[0014] This embodiment will now be described in detail with reference to the drawings.

[0015] 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. Furthermore, LTE that can connect with NR via Multi-Radio Dual Connectivity (MR-DC) may be distinguished from conventional LTE. Also, LTE using 5GC in the Core Network (CN) may be distinguished from conventional LTE using 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. The following description uses terms related to LTE and NR, but this embodiment may be applied to other technologies using other terms. Also, the term E-UTRA in this embodiment may be replaced with the term LTE, and the term LTE may be replaced with the term E-UTRA.

[0016] In this embodiment, the names of each node and entity, and the processing at each node and entity, will be described when the wireless access technology is E-UTRA or NR. However, this embodiment may be used with other wireless access technologies. The names of each node and entity in this embodiment may be different.

[0017] Figure 1 is a schematic diagram of the communication system according to this embodiment. The functions of each node, wireless access technology, core network, interface, etc., described using Figure 1 are only some of the functions closely related to this embodiment, and other functions may also be present.

[0018] E-UTRA100 may be a wireless access technology. E-UTRA100 may also be an air interface between UE122 and eNB102. The air interface between UE122 and eNB102 may be called the Uu interface. eNB (E-UTRAN Node B)102 may be a base station device. eNB102 may have the E-UTRA protocol described below. The E-UTRA protocol may consist of the E-UTRA User Plane (UP) protocol and the E-UTRA Control Plane (CP) protocol described below. eNB102 may terminate the E-UTRA User Plane (UP) protocol and the E-UTRA Control Plane (CP) protocol to UE122. The wireless access network composed of eNB may be called E-UTRAN.

[0019] The EPC (Evolved Packet Core) 104 may be a core network. Interface 112 is an interface between eNB 102 and EPC 104 and may be called the S1 interface. Interface 112 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 112 may terminate at a Mobility Management Entity (MME: not shown) in EPC 104. The user plane interface of interface 112 may terminate at a Serving Gateway (S-GW: not shown) in EPC 104. The control plane interface of interface 112 may be called the S1-MME interface. The user plane interface of interface 112 may be called the S1-U interface.

[0020] One or more eNB102s may be connected to the EPC104 via interface 112. Interfaces may exist between multiple eNB102s connected to the EPC104 (not shown). Interfaces between multiple eNB102s connected to the EPC104 may be called X2 interfaces.

[0021] NR106 may be a wireless access technology. NR106 may also be an air interface between UE122 and gNB108. The air interface between UE122 and gNB108 may be called a Uu interface. gNB108 may be a base station device. gNB108 may have the NR protocol described below. The NR protocol may consist of the NR User Plane (UP) protocol and the NR Control Plane (CP) protocol described below. gNB108 may terminate the NR User Plane (UP) protocol and the NR Control Plane (CP) protocol to UE122.

[0022] 5GC110 may be the core network. Interface 116 is the interface between gNB108 and 5GC110 and may be called the 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 be terminated by the Access and Mobility Management Function (AMF: not shown) in 5GC110. The user plane interface of interface 116 may be terminated by the User Plane Function (UPF: not shown) in 5GC110. The control plane interface of interface 116 may be called the NG-C interface. The user plane interface of interface 116 may be called the NG-U interface.

[0023] One or more gNB108s may be connected to the 5GC110 via interface 116. Interfaces may exist between multiple gNB108s connected to the 5GC110 (not shown). The interfaces between multiple gNB108s connected to the 5GC110 may be called Xn interfaces.

[0024] eNB102 may have the function of connecting to 5GC110. eNB102 having the function of connecting to 5GC110 may be called ng-eNB. Interface 114 is the interface between eNB102 and 5GC110 and may be called NG interface. Interface 114 may have a control plane interface through which control signals pass, and / or a user plane interface through which user data passes. The control plane interface of interface 114 may be terminated at the AMF in 5GC110. The user plane interface of interface 114 may be terminated at the UPF in 5GC110. The control plane interface of interface 114 may be called NG-C interface. The user plane interface of interface 114 may be called NG-U interface. A radio access network consisting of ng-eNB or gNB may be called NG-RAN. NG-RAN, E-UTRAN, etc. may simply be called a network. Also, the network may include eNB, ng-eNB, and gNB, etc.

[0025] One or more eNB102s may be connected to the 5GC110 via interface 114. Interfaces may exist between multiple eNB102s connected to the 5GC110 (not shown). Interfaces between multiple eNB102s connected to the 5GC110 may be called Xn interfaces. Furthermore, an eNB102 connected to the 5GC110 and a gNB108 connected to the 5GC110 may be connected via interface 120. Interface 120 between an eNB102 connected to the 5GC110 and a gNB108 connected to the 5GC110 may be called Xn interfaces.

[0026] gNB108 may have the function of connecting to EPC104. gNB108 with the function of connecting to EPC104 may be called en-gNB. Interface 118 is the interface between gNB108 and EPC104 and may be called the S1 interface. Interface 118 may have a user plane interface through which user data passes. The user plane interface of interface 118 may be terminated at the S-GW (not shown) in EPC104. The user plane interface of interface 118 may be called the S1-U interface. Also, eNB102 connected to EPC104 and gNB108 connected to EPC104 may be connected by interface 120. Interface 120 between eNB102 connected to EPC104 and gNB108 connected to EPC104 may be called the X2 interface.

[0027] Interface 124 is the interface between EPC104 and 5GC110, and may be an interface that passes only CP, only UP, or both CP and UP. In addition, some or all of interfaces such as Interface 114, Interface 116, Interface 118, Interface 120, and Interface 124 may not exist depending on the communication system provided by the telecommunications carrier.

[0028] UE122 may be a terminal device capable of receiving system information and paging messages transmitted from eNB102 and / or gNB108. UE122 may also be a terminal device capable of wireless connection with eNB102 and / or gNB108. Furthermore, UE122 may be a terminal device capable of simultaneously establishing wireless connections with eNB102 and gNB108. UE122 may have the E-UTRA protocol and / or the NR protocol. Note that the wireless connection may be a Radio Resource Control (RRC) connection.

[0029] Furthermore, UE122 may be a terminal device capable of connecting to EPC104 and / or 5GC110 via eNB102 and / or gNB108. If the core network to which eNB102 and / or gNB108, with which UE122 communicates, is connected is EPC104, then each Data Radio Bearer (DRB) established between UE122 and eNB102 and / or gNB108, as described below, may be uniquely associated with each EPS (Evolved Packet System) bearer passing through EPC104. Each EPS bearer may be identified by an EPS bearer identifier (Identity, or ID). Furthermore, the same QoS may be guaranteed for data such as IP packets and Ethernet® frames passing through the same EPS bearer.

[0030] Furthermore, if the core network to which UE122 communicates with eNB102 and / or gNB108 is connected is 5GC110, then each DRB established between UE122 and eNB102 and / or gNB108 may be further associated with one of the PDU (Packet Data Unit) sessions established within 5GC110. Each PDU session may have one or more QoS flows. 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 also be identified by a QoS flow identifier (Identity, or ID). Furthermore, the same QoS may be guaranteed for data such as IP packets and Ethernet frames passing through the same QoS flow.

[0031] EPC104 does not need to have PDU sessions and / or QoS flows. Similarly, 5GC110 does not need to have an EPS bearer. When UE122 is connected to EPC104, UE122 will have EPS bearer information, but not information within PDU sessions and / or QoS flows. Similarly, when UE122 is connected to 5GC110, UE122 will have information within PDU sessions and / or QoS flows, but not information within EPS bearers.

[0032] In the following description, eNB102 and / or gNB108 will also be simply referred to as base station equipment, and UE122 will also be simply referred to as terminal equipment or UE.

[0033] Figure 2 is a diagram of an example of the E-UTRA protocol architecture according to this embodiment. Figure 3 is a diagram of an example of the NR protocol architecture according to this embodiment. Note that the functions of each protocol described using Figure 2 and / or Figure 3 are some of the functions closely related to this embodiment, and other functions may be present. In this embodiment, the uplink (UL) may be a link from a terminal device to a base station device. Also in this embodiment, the downlink (DL) may be a link from a base station device to a terminal device.

[0034] Figure 2(A) is a diagram of the E-UTRA user plane (UP) protocol stack. As shown in Figure 2(A), the E-UTRA UP protocol may be a protocol between UE122 and eNB102. That is, the E-UTRA UP protocol may be a protocol that terminates at eNB102 on the network side. As shown in Figure 2(A), the E-UTRA user plane protocol stack may consist of a radio physical layer (PHY) 200, a medium access control layer (MAC) 202, a radio link control layer (RLC) 204, and a packet data convergence protocol layer (PDCP) 206.

[0035] Figure 3(A) is a diagram of the NR User Plane (UP) protocol stack. As shown in Figure 3(A), the NRUP protocol may be a protocol between UE122 and gNB108. That is, the NR UP protocol may be a protocol that terminates at gNB108 on the network side. As shown in Figure 3(A), the NR User Plane protocol stack may consist of the wireless physical layer PHY300, the media access control layer MAC302, the wireless link control layer RLC304, the packet data convergence protocol layer PDCP306, and the service data adaptation protocol layer (service data adaptation protocol layer) SDAP (Service Data Adaptation Protocol)310.

[0036] Figure 2(B) shows the configuration of the E-UTRA control plane (CP) protocol. As shown in Figure 2(B), in the E-UTRA CP protocol, the Radio Resource Control (RRC) 208, which is the radio resource control layer, may be a protocol between the UE122 and the eNB102. That is, the RRC 208 may be a protocol that terminates at the eNB102 on the network side. Also, in the E-UTRA CP protocol, the Non Access Stratum (NAS) 210, which is the non-Access Stratum (AS) layer, may be a protocol between the UE122 and the MME. That is, the NAS 210 may be a protocol that terminates at the MME on the network side.

[0037] Figure 3(B) is a diagram of the NR control plane (CP) protocol configuration. As shown in Figure 3(B), in the NR CP protocol, the RRC308, which is the radio resource control layer, may be a protocol between the UE122 and the gNB108. That is, the RRC308 may be a protocol that terminates at the gNB108 on the network side. Also, in the NR CP protocol, the NAS312, which is a non-AS layer, may be a protocol between the UE122 and the AMF. That is, the NAS312 may be a protocol that terminates at the AMF on the network side.

[0038] The AS (Access Stratum) layer may be a layer that terminates between UE122 and eNB102 and / or gNB108. That is, the AS layer may be a layer containing some or all of PHY200, MAC202, RLC204, PDCP206, and RRC208, and / or a layer containing some or all of PHY300, MAC302, RLC304, PDCP306, SDAP310, and RRC308.

[0039] In this embodiment, the following terms may be used without distinguishing between the E-UTRA protocol and the NR protocol, and may include PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer). In this case, 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, or they may be the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), RRC (RRC layer), and NAS (NAS layer) of the NR protocol. Also, SDAP (SDAP layer) may be the SDAP (SDAP layer) of the NR protocol.

[0040] Furthermore, in this embodiment, when distinguishing between the E-UTRA protocol and the NR protocol, PHY200, MAC202, RLC204, PDCP206, and RRC208 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. Additionally, PHY200, MAC202, RLC204, PDCP206, and RRC208 may also be described 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 the E-UTRA protocol and the NR protocol, PHY300, MAC302, RLC304, PDCP306, and RRC308 are sometimes referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively. Alternatively, PHY300, MAC302, RLC304, PDCP306, and RRC308 may be written as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

[0041] This section describes entities in the AS layer of E-UTRA and / or NR. Entities that possess some or all of the functions of the MAC layer may be called MAC entities. Entities that possess some or all of the functions of the RLC layer may be called RLC entities. Entities that possess some or all of the functions of the PDCP layer may be called PDCP entities. Entities that possess some or all of the functions of the SDAP layer may be called SDAP entities. Entities that possess some or all of the functions of the RRC layer may be called RRC entities. MAC entities, RLC entities, PDCP entities, SDAP entities, and RRC entities may be replaced with MAC, RLC, PDCP, SDAP, and RRC, respectively.

[0042] Furthermore, the data provided from MAC, RLC, PDCP, and SDAP to lower layers, and / or the 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, the data provided from higher layers to MAC, RLC, PDCP, and SDAP, and / or the data provided from MAC, RLC, PDCP, and SDAP to higher layers, may be referred to as MAC SDU (Service Data Unit), RLC SDU, PDCP SDU, and SDAP SDU, respectively. In addition, a segmented RLC SDU may be referred to as an RLC SDU segment.

[0043] Here, the base station equipment and the terminal equipment exchange (send and receive) signals at the higher layer. For example, the base station equipment and the terminal equipment may send and receive RRC messages (also called RRC message, RRC information, or RRC signalling) at the Radio Resource Control (RRC) layer. The base station equipment and the terminal equipment may also send and receive MAC control elements at the MAC (Medium Access Control) layer. Furthermore, the RRC layer of the terminal equipment acquires system information broadcast from the base station equipment. Here, RRC messages, system information, and / or MAC control elements are also called higher layer signals (higher layer signalling) or higher layer parameters (higher layer parameters). Each parameter included in the higher layer signal received by the terminal equipment may also be called a higher layer parameter. In the processing of the PHY layer, the higher layer refers to the layer above the PHY layer, and therefore may 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 refer to one or more layers such as the RRC layer, RLC layer, PDCP layer, and NAS layer. Hereinafter, the meaning of "A is given (provided) in 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 that received A is provided (provided) from the upper layer of the terminal device to the physical layer of the terminal device. For example, "being provided with upper layer parameters" in a terminal device may mean that it receives an upper layer signal from the base station device, and the upper layer parameters contained in the received upper layer signal are provided from the upper layer of the terminal device to the physical layer of the terminal device. Setting upper layer parameters in a terminal device may mean that the upper layer parameters are given (provided) to the terminal device.For example, the setting of upper layer parameters in the terminal device may mean that the terminal device receives an upper layer signal from the base station device and sets the received upper layer parameters in the upper layer. However, the setting of upper layer parameters in the terminal device may also include the setting of default parameters that are pre - given to the upper layer of the terminal device. When explaining the transmission of an RRC message from the terminal device to the base station device, the expression of submitting a message from the RRC entity of the terminal device to the lower layer (lower layer: lower layer) may be used. In the terminal device, "submitting a message to the lower layer" from the RRC entity may mean submitting the message to the PDCP layer. In the terminal device, "submitting (submit) a message to the lower layer" from the RRC layer may mean that since the RRC message is transmitted using SRBs (such as SRB0, SRB1, SRB2, SRB3), it means submitting it to the PDCP entity corresponding to each SRB. When the RRC entity of the terminal device receives an indication from the lower layer, the lower layer may mean one or more of the PHY layer, MAC layer, RLC layer, PDCP layer, etc.

[0044] An example of the functions of the PHY will be described. The PHY of the terminal device may have the function of receiving data transmitted from the PHY of the base station device via the downlink (Downlink: DL) physical channel. The PHY of the terminal device may have the function of transmitting data to the PHY of the base station device via the uplink (Uplink: UL) physical channel. The PHY may be connected to the upper - level MAC via the transport channel. The PHY may pass data to the MAC via the transport channel. Also, the PHY may 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.

[0045] Here, the physical channel will be described. The physical channels used for wireless communication between the terminal device and the base station device may include the following physical channels.

[0046] 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)

[0047] PBCH may be used to notify the system information required by the terminal device.

[0048] Also, in NR, PBCH may be used to notify the time index (SSB-Index) within the period of the Synchronization Signal Block (SSB).

[0049] PDCCH may be used in downlink wireless communication (wireless communication from base station equipment to terminal equipment) to transmit (or carry) Downlink Control Information (DCI). Here, one or more DCIs (which may also be called DCI formats) may be defined for the transmission of downlink control information. That is, fields for downlink control information may be defined as DCIs and mapped to information bits. PDCCH may be transmitted in PDCCH candidates. Terminal equipment may monitor a set of PDCCH candidates in a serving cell. Monitoring a set of PDCCH candidates may mean attempting to decode a PDCCH according to a certain DCI format. Terminal equipment may also use a CORESET (Control Resource Set) to monitor a set of PDCCH candidates. The DCI format may be used for scheduling PUSCHs in a serving cell. PUSCHs may be used for transmitting user data or RRC messages, as described later.

[0050] PUCCH may be used to transmit Uplink Control Information (UCI) in uplink wireless communication (wireless communication from terminal equipment to base station equipment). Here, Uplink Control Information may include Channel State Information (CSI), which is used to indicate the state of the downlink channel. Furthermore, Uplink Control Information may include Scheduling Requests (SR), which are used to request UL-SCH (Uplink Shared Channel) resources. Furthermore, Uplink Control Information may include HARQ-ACK (Hybrid Automatic Repeat reQuest ACKnowledgement).

[0051] PDSCH may be used to transmit downlink data (DL-SCH: Downlink Shared Channel) from the MAC layer. In the case of downlinks, PDSCH may also be used to transmit system information (SI) and random access responses (RAR).

[0052] PUSCH may be used to transmit uplink data (UL-SCH: Uplink Shared Channel) from the MAC layer or HARQ-ACK and / or CSI along with uplink data. Alternatively, PUSCH may be used to transmit CSI only, or HARQ-ACK and CSI only. In other words, PUSCH may be used to transmit UCI only. Furthermore, PDSCH or PUSCH may be used to transmit RRC signaling (also called RRC messages) and MAC CE. Here, in PDSCH, the RRC signaling transmitted from the base station equipment may be a common signaling for multiple terminal devices within a cell. Also, the RRC signaling transmitted from the base station equipment may be a dedicated signaling for a particular terminal device (also called dedicated signaling). In other words, terminal device-specific information may be transmitted using a dedicated signaling for a particular terminal device. Furthermore, PUSCH may be used to transmit UE Capability on the uplink.

[0053] PRACH may be used to send a random access preamble. PRACH may also be used to indicate the initial connection establishment procedure, handover procedure, connection re-establishment procedure, synchronization (timing adjustment) for uplink transmissions, and requests for UL-SCH resources.

[0054] An example of MAC functionality is described below. 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 a Logical Channel Identity (Logical Channel ID). MAC may be connected to the higher-level RLC via logical channels. Logical channels may be divided into control channels that transmit control information and traffic channels that transmit user information, depending on the type of information being transmitted. 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 from the PHY and providing them to the higher layer via the logical channel 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 a function to report scheduling information. The MAC may have a function to prioritize between terminal devices using dynamic scheduling. The MAC may also have a function to prioritize between logical channels within a single terminal device. The MAC may also have a function to prioritize overlapping resources within a single terminal device. The E-UTRA MAC may have a function to identify Multimedia Broadcast Multicast Services (MBMS). The NR MAC may also have a function to identify Multicast Broadcast Service (MBS). The MAC may have a function to select the transport format.A MAC may have functions for discontinuous reception (DRX) and / or discontinuous transmission (DTX), random access (RA) procedures, a power headroom report (PHR) function to notify information on available power, and a buffer status report (BSR) function to notify information on the amount of data in the transmit buffer. An NR MAC may have a bandwidth adaptation (BA) function. The MAC PDU format used in E-UTRA MACs and the MAC PDU format used in NR MACs may be different. A MAC PDU may also include MAC control elements (MAC CEs), which are elements for controlling the MAC.

[0055] This section describes the logical channels used for uplink (UL) and / or downlink (DL) in E-UTRA and / or NR.

[0056] BCCH (Broadcast Control Channel) may be a downlink logical channel for broadcasting control information, such as system information (SI).

[0057] A PCCH (Paging Control Channel) may be a downlink logical channel for carrying paging messages.

[0058] A Common Control Channel (CCCH) may be a logical channel for transmitting control information between a terminal device and a base station device. A CCCH may be used when a terminal device does not have an RRC connection. A CCCH may also be used between a base station device and multiple terminal devices.

[0059] A DCCH (Dedicated Control Channel) may be a logical channel for transmitting dedicated control information in a point-to-point, bidirectional manner between a terminal device and a base station device. Dedicated control information may be control information specific to each terminal device. A DCCH may be used when the terminal device has an RRC connection.

[0060] A Dedicated Traffic Channel (DTCH) 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 specific to each terminal device. A DTCH may exist on both the uplink and downlink.

[0061] This section describes the mapping between logical channels and transport channels for uplinks in E-UTRA and / or NR.

[0062] CCCH may be mapped to UL-SCH (Uplink Shared Channel), which is an uplink transport channel.

[0063] DCCH may be mapped to UL-SCH (Uplink Shared Channel), which is an uplink transport channel.

[0064] DTCH may be mapped to UL-SCH (Uplink Shared Channel), which is an uplink transport channel.

[0065] This section describes the mapping between logical channels and transport channels in downlinks in E-UTRA and / or NR.

[0066] BCCH may be mapped to a downlink transport channel, which is a BCH (Broadcast Channel) and / or DL-SCH (Downlink Shared Channel).

[0067] The PCCH may be mapped to the PCH (Paging Channel), which is a downlink transport channel.

[0068] CCCH may be mapped to DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

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

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

[0071] An example of RLC functionality is described below. RLC may be called an RLC sublayer. E-UTRA RLC may have the function of segmenting and / or concatenating data provided from the upper layer PDCP and providing it to the lower layer. E-UTRA RLC may have the function of reassembling and reordering data provided from the lower layer and providing it to the upper layer. NR RLC may have the function of adding a sequence number to data provided from the upper layer PDCP that is independent of the sequence number added by the PDCP. NR RLC may also have the function of segmenting data provided from the PDCP and providing it to the lower layer. NR RLC may also have the function of reassembling data provided from the lower layer and providing it to the upper layer. RLC may also have a data retransmission function and / or an automatic repeat request (ARQ) function. RLC may also have a function to perform error correction using ARQ. The control information sent from the receiver to the transmitter of RLC to perform ARQ, indicating data that needs to be retransmitted, may be called a status report. The instruction to send a status report sent from the transmitter to the receiver of RLC may be called a poll. RLC may also have a function to detect data duplication. RLC may also have a data discard function. RLC may have three modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). In TM, data received from the upper layer is not split, and an RLC header does not need to be added. The TM RLC entity is a unidirectional entity, and the terminal device may set the TM RLC entity as a transmitting TM RLC entity or a receiving TM RLC entity.UM performs data splitting and / or merging, adds an RLC header, etc., received from higher layers, but does not need to control data retransmission. UM RLC entities may be unidirectional or bidirectional. If a UM RLC entity is unidirectional, the terminal device may configure it as a transmitting UM RLC entity or a receiving UM RLC entity. If a UM RLC entity is bidirectional, the terminal device may configure it as a UM RLC entity consisting of a transmitting side and a receiving side. AM performs data splitting and / or merging, adds an RLC header, and controls data retransmission, etc., received from higher layers. AM RLC entities are bidirectional, and the terminal device may configure them as AM RLC entities consisting of a transmitting side and a receiving side. Data provided to lower layers by TM, and / or data provided from lower layers, may be called TMD PDUs. Furthermore, data provided to lower layers by UM, and / or data provided by lower layers, may be called UMDPDU. Similarly, data provided to lower layers by AM, or data provided by lower layers, may be called AMD PDU. The RLC PDU format used in E-UTRA RLC and the RLC PDU format used in NR RLC may be different. Additionally, there may be data RLC PDUs and control RLC PDUs. Data RLC PDUs may be called RLC DATA PDUs (RLC Data PDUs). Control RLC PDUs may be called RLC CONTROL PDUs (RLC Control PDUs).

[0072] This section describes some examples of PDCP functionality. PDCP may be referred to as the 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 the wireless section. The protocol used for compressing and decompressing IP packet headers may be called the ROHC (Robust Header Compression) protocol. The protocol used for compressing and decompressing Ethernet frame headers may be called the EHC (Ethernet® Header Compression) protocol. PDCP may also have data encryption / decryption functions. PDCP may also have data integrity protection and integrity verification functions. 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 to discard duplicate received data. A 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 and the PDCP PDU format used in NR PDCP may be different. Furthermore, there may be 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).

[0073] This section describes an example of SDAP functionality. SDAP is a Service Data Adaptive Protocol Layer (SPD). SDAP may have the function of mapping downlink QoS flows sent from the 5GC110 to the terminal device via the base station equipment to the Data Radio Bearer (DRB), and / or mapping uplink QoS flows sent from the terminal device to the 5GC110 via the base station equipment to the DRB. SDAP may also have the function of storing mapping rule information. SDAP may also have the function of marking QoS flow identifiers (QoS Flow ID: QFI). Note that there may be data SDAP PDUs and control SDAP PDUs. Data SDAP PDUs may be called SDAP DATA PDUs (SDAP Data PDUs). Control SDAP PDUs may be called SDAP CONTROL PDUs (SDAP Control PDUs). Note that there may be one SDAP entity for each PDU session in the terminal device.

[0074] An example of RRC functionality is described below. RRC may have broadcast functionality. RRC may have paging functionality from EPC104 and / or 5GC110. RRC may have paging functionality from eNB102 connected to gNB108 or 5GC110. RRC may also have RRC connection management functionality. RRC may also have wireless bearer control functionality. RRC may also have cell group control functionality. RRC may also have mobility control functionality. RRC may also have terminal device measurement reporting and terminal device measurement reporting control functionality. RRC may also have QoS management functionality. RRC may also have wireless link failure detection and recovery functionality. The RRC may use RRC messages to perform functions such as broadcasting, paging, RRC connection management, wireless bearer control, cell group control, mobility control, terminal device measurement reporting and terminal device measurement reporting control, QoS management, and wireless link failure detection and recovery. Note that the RRC messages and parameters used in E-UTRA RRC may differ from those used in NR RRC.

[0075] RRC messages may be sent using the logical channels BCCH, PCCH, CCCH, or DCCH. RRC messages sent using DCCH may also be referred to as dedicated RRC signaling or simply RRC signaling.

[0076] RRC messages sent using BCCH may include, for example, a Master Information Block (MIB), a System Information Block (SIB) of each type, or other RRC messages. RRC messages sent using PCCH may include, for example, a paging message or other RRC messages.

[0077] RRC messages sent in the uplink (UL) direction using CCCH may include, for example, RRC Setup Request, RRC Resume Request, RRC Reestablishment Request, and RRC System Info Request. They may also include, for example, RRC Connection Request, RRC Connection Resume Request, and RRC Connection Reestablishment Request. Other RRC messages may also be included.

[0078] RRC messages sent in the downlink (DL) direction using CCCH may include, for example, RRC Connection Reject messages, RRC Connection Setup messages, RRC Connection Reestablishment messages, and RRC Connection Reestablishment Reject messages. They may also include, for example, RRC Reject messages and RRC Setup messages. Other RRC messages may also be included.

[0079] RRC signaling sent in the uplink (UL) direction using 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, and an UE Capability Information message. It may also include, 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, and an UE Capability Information message. Other RRC signaling may also be included.

[0080] RRC signaling sent in the downlink (DL) direction using DCCH may include, for example, RRC Connection Reconfiguration messages, RRC Connection Release messages, Security Mode Command messages, and UE Capability Enquiry messages. It may also include, for example, RRC Reconfiguration messages, RRC Resume messages, RRC Release messages, RRC Reestablishment messages, Security Mode Command messages, and UE Capability Enquiry messages. Other RRC signaling may also be included.

[0081] This section describes some examples of NAS functionality. A NAS may have authentication capabilities. It may also have mobility management capabilities. Furthermore, a NAS may have security control capabilities.

[0082] The aforementioned PHY, MAC, RLC, PDCP, SDAP, RRC, and NAS functions are merely examples, and some or all of each function may not be implemented. Furthermore, some or all of the functions of each layer may be included in other layers.

[0083] Next, we will explain the state transitions of UE122 in LTE and NR. When a UE122 connected to an EPC or 5GC has an RRC connection, it may be in the RRC_CONNECTED state. The state of having an RRC connection may include the state in which the UE122 holds some or all of the UE context described below. The state of having an RRC connection may also include the state in which the UE122 can send and / or receive unicast data. When the RRC connection is suspended, the UE122 may be in the RRC_INACTIVE state. The UE122 may be in the RRC_INACTIVE state when it is connected to a 5GC and the RRC connection is suspended. When the UE122 is neither in the RRC_CONNECTED state nor the RRC_INACTIVE state, it may be in the RRC_IDLE state.

[0084] Note that if UE122 is connected to EPC, it does not have the RRC_INACTIVE state, but E-UTRAN may initiate the suspension of the RRC connection. When UE122 is connected to EPC and the RRC connection is suspended, UE122 may transition to the RRC_IDLE state, retaining the UE's AS context and the identifier (resumeIdentity) used for resuming. The upper layer of the UE122's RRC layer (e.g., the NAS layer) may initiate the resumption of the suspended RRC connection if UE122 retains the UE's AS context, E-UTRAN has permitted the resumption of the RRC connection, and UE122 needs to transition from the RRC_IDLE state to the RRC_CONNECTED state.

[0085] The definition of hibernation may differ between UE122 connected to EPC104 and UE122 connected to 5GC110. Furthermore, all or part of the procedure for UE122 to resume from hibernation may differ depending on whether UE122 is connected to EPC (when UE122 is hibernating in the RRC_IDLE state) or UE122 is connected to 5GC (when UE122 is hibernating in the RRC_INACTIVE state).

[0086] The RRC_CONNECTED state, RRC_INACTIVE state, and RRC_IDLE state may be referred to as connected mode, inactive mode, and idle mode, respectively, or as RRC connected mode, RRC inactive mode, and RRC idle mode.

[0087] The UE context held by UE122 may include all or part of the following: PDU session context, security key, UE radio capability information, and UE security capability information. The UE context held by either or all of eNB102 and gNB108 may contain the same information as the UE context held by UE122, or it may contain different information than that contained in the UE context held by UE122. Furthermore, the UE context may include all or part of the UE's AS context as described below.

[0088] The AS context of the UE held by UE122 may include all or part of the following information: the current RRC settings, the current security context, the PDCP status including the ROHC (RObust Header Compression) status, the C-RNTI (Cell Radio Network Temporary Identifier) ​​used by the source PCell, the cell identifier, and the physical cell identifier of the source PCell. The AS context of the UE held by any or all of eNB102 and gNB108 may include the same information as the AS context of the UE held by UE122, or it may include information different from the information included in the AS context of the UE held by UE122.

[0089] The security context may include all or part of the following at the AS level: the encryption key, the NH (Next Hop parameter), the NCC (Next Hop Chaining Counter parameter) used to derive the next hop access key, the identifier of the selected AS-level encryption algorithm, and the counter used for replay protection.

[0090] Next, we will explain the Serving Cell. In terminal devices in an RRC connection state where the CA and / or DC described later are not configured, the Serving Cell may consist of one Primary Cell (PCell). In terminal devices in an RRC connection state where the CA and / or DC described later are configured, multiple Serving Cells may mean a set of multiple cells consisting of one or more Special Cells (SpCells) and one or more all Secondary Cells (SCells). SpCells may support PUCCH transmission and contention-based Random Access (CBRA), and SpCells may always be activated. A 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 connection state. A PCell may also be a cell used in the RRC connection re-establishment procedure when a terminal device re-establishes the RRC connection. A PCell may also be a cell used in the random access procedure during handover. PSCell may be a cell used in the random access procedure when adding a secondary node, as described later. SpCell may be a cell used for purposes other than those mentioned above.

[0091] If a group of serving cells configured by a terminal device consists of a SpCell and one or more SCells, it may be considered that the terminal device is configuring carrier aggregation (CA). Furthermore, for a terminal device configuring CA, a cell providing additional radio resources to a SpCell may be considered an SCell.

[0092] A group of serving cells configured by a terminal device in RRC, where the serving cells that use the same timing reference cell and the same timing advance value for the cell on which the terminal device sets the uplink, may be called a Timing Advance Group (TAG). A TAG containing a MAC entity SpCell may represent a Primary Timing Advance Group (PTAG). A TAG other than a PTAG may represent a Secondary Timing Advance Group (STAG). One or more of the aforementioned TAGs may be configured for each cell group, as described later.

[0093] This section describes cell groups, which are configured in the upper layer (RRC, etc.) of terminal devices. A cell group may consist of one SpCell. Alternatively, a cell group may consist of one SpCell and one or more SCells. In other words, a cell group may consist of one SpCell and, optionally, one or more SCells. A cell group may also be described as a set of cell(s).

[0094] Dual Connectivity (DC) is a technology that enables data communication using the 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, cell groups may be added to terminal devices from the base station device. To perform DC, the first base station device may add a second base station device. The first base station device may be called the Master Node (MN). The cell group configured by the Master Node may be called the Master Cell Group (MCG). The second base station device may be called the Secondary Node (SN). The cell group configured by the Secondary Node may be called the Secondary Cell Group (SCG). The Master Node and Secondary Node may be configured within the same base station device.

[0095] Furthermore, when a terminal device does not configure a DC, the cell group configured by the terminal device may be called an MCG. Also, 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 the terminal device does not configure a DC may be called an NR standalone.

[0096] Furthermore, Multi-Radio Dual Connectivity (MR-DC) may be a technology that performs DC using E-UTRA for MCG and NR for SCG. Also, MR-DC may be a technology that performs DC using NR for MCG and E-UTRA for SCG. Also, MR-DC may be a technology that performs DC using NR for both MCG and SCG. MR-DC may be a technology included in DC. Examples of MR-DC using E-UTRA for MCG and NR for SCG include EN-DC (E-UTRA-NR Dual Connectivity) using EPC for the core network, and NGEN-DC (NG-RAN E-UTRA-NR Dual Connectivity) using 5GC for the core network. Also, an example of MR-DC using NR for MCG and E-UTRA for SCG is NE-DC (NR-E-UTRA Dual Connectivity) using 5GC for the core network. Also, an example of MR-DC using NR for MCG and E-UTRA for SCG is NR-DC (NR-NR Dual Connectivity) using 5GC for the core network.

[0097] In a terminal device, there may be one MAC entity for each cell group. For example, when a terminal device sets up a 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 a terminal device may always be established in all states of the terminal device (RRC idle state, RRC connected state, and RRC inactive state, etc.). The MAC entity for the SCG in a terminal device may be created by the terminal device when it sets up the SCG. The MAC entities for each cell group in a terminal device may be set when the terminal device receives RRC signaling from the base station device. When a MAC entity is associated with an MCG, SpCell may mean PCell. When a MAC entity is associated with an SCG, SpCell may mean Primary SCG Cell (PSCell). When a MAC entity is not associated with a cell group, SpCell may mean PCell. PCell, PSCell, and SCell are serving cells. In EN-DC and NGEN-DC, the MAC entity for MCG may be an E-UTRA MAC entity, and the MAC entity for SCG may be an NR MAC entity. Similarly, in NE-DC, the MAC entity for MCG may be an NR MAC entity, and the MAC entity for SCG may be an E-UTRA MAC entity. Furthermore, in NR-DC, both the MAC entities for MCG and SCG may be NR MAC entities. Note that the statement that there is one MAC entity for each cell group can be rephrased as "there is one MAC entity for each SpCell." Similarly, the statement that there is one MAC entity for each cell group can be rephrased as "there is one MAC entity for each SpCell."

[0098] This section describes radio bearers. When a terminal device communicates with a base station device, a radio connection may be established between the terminal device and the base station device by establishing a radio bearer (RB). A radio bearer used in CP may be called a signaling radio bearer (SRB). A radio bearer used in UP may be called a data radio bearer (DRB). Each radio bearer may be assigned a radio bearer identifier (Identity: ID). The radio bearer identifier for SRBs may be called an SRB identifier (SRB Identity, or SRB ID). The radio bearer identifier for DRBs may be called a DRB identifier (DRB Identity, or DRB ID). For E-UTRA, SRB0 to SRB2 may be defined, and other SRBs may also be defined. For NR, SRB0 to SRB3 may be defined, and other SRBs may also 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 SRB2 is established. RRC signaling transmitted and / or received using SRB1 may include piggybacked NAS signaling. All RRC and NAS signaling transmitted and / or received using SRB1 may use the logical channel DCCH. SRB2 may be an SRB for NAS signaling and for RRC signaling including logged measurement information. All RRC and NAS signaling transmitted and / or received using SRB2 may use the logical channel DCCH. SRB2 may also have a lower priority than SRB1. SRB3 may be an SRB for transmitting and / or receiving specific RRC signaling when a terminal device sets EN-DC, NGEN-DC, NR-DC, etc.All RRC signaling and NAS signaling transmitted and / or received using SRB3 may use the logical channel DCCH. Other SRBs may be provided for other purposes. The DRB may be a wireless bearer for user data. RRC signaling transmitted and / or received using the DRB may use the logical channel DTCH.

[0099] This section describes the wireless bearer in the terminal device. The wireless bearer may include an RLC bearer. An RLC bearer may consist of one or two RLC entities and a logical channel. If there are two RLC entities in the RLC bearer, the RLC entities may be a TM RLC entity and / or a transmit RLC entity and a receive RLC entity in unidirectional UM mode. SRB0 may consist of one RLC bearer. The RLC bearer of SRB0 may consist of a TM RLC entity and a logical channel. SRB0 may always be established in the terminal device in all states (RRC idle state, RRC connected state, and RRC inactive state, etc.). SRB1 may be established and / or configured by the terminal device in RRC when the terminal device transitions from the RRC idle state to the RRC connected state, based on RRC signaling received from the base station device. SRB1 may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB1 may consist of an AM RLC entity and a logical channel. SRB2 may be established and / or configured on a terminal device by RRC signaling received from the base station device by a terminal device in an RRC connection state with AS security activated. SRB2 may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB2 may consist of an AM RLC entity and a logical channel. Note that the PDCP on the base station side of SRB1 and SRB2 may be located on the master node. SRB3 may be established and / or configured on a terminal device by RRC signaling received from the base station device by a terminal device in an RRC connection state with AS security activated when a secondary node is added or when a secondary node is changed in EN-DC, NGEN-DC, or NR-DC. SRB3 may be a direct SRB between the terminal device and the secondary node. SRB3 may consist of one PDCP entity and one or more RLC bearers. The RLC bearers of SRB3 may consist of AM's RLC entities and logical channels.The PDCP on the base station side of SRB3 may be located on a secondary node. The DRB may be established and / or configured by the terminal device via RRC signaling received from the base station device by a terminal device in an RRC connection state with AS security activated. The DRB may consist of one PDCP entity and one or more RLC bearers. The RLC bearers of the DRB may consist of an AM or UM RLC entity and a logical channel.

[0100] In MR-DC, a wireless bearer with a PDCP on the master node may be called an MN-terminated bearer. Similarly, a wireless bearer with a PDCP on the secondary node may be called an SN-terminated bearer. Furthermore, in MR-DC, a wireless bearer with an RLC bearer present only in the MCG may be called an MCG bearer. Similarly, a wireless bearer with an RLC bearer present only in the SCG may be called an SCG bearer. Finally, in a DC, a wireless bearer with an RLC bearer present in both the MCG and SCG may be called a split bearer.

[0101] When a terminal device configures MR-DC, the bearer types of SRB1 and SRB2 established and / or configured by the terminal device may be MN-terminated MCG bearer and / or MN-terminated split bearer. Also, when a terminal device configures MR-DC, the bearer type of SRB3 established and / or configured by the terminal device may be SN-terminated SCG bearer. Also, when a terminal device configures MR-DC, the bearer type of DRB established and / or configured by the terminal device may be any of all bearer types.

[0102] For RLC bearers established and / or configured by a terminal device in a cell group composed of E-UTRA, the RLC entities established and / or configured by the terminal device may be E-UTRA RLC. Similarly, for RLC bearers established and / or configured by a terminal device in a cell group composed of NR, the RLC entities established and / or configured by the terminal device may be NR RLC. When a terminal device configures EN-DC, the PDCP entities established and / or configured by the terminal device for MN-terminated MCG bearers may be either E-UTRA PDCP or NR PDCP. Furthermore, when a terminal device configures EN-DC, the PDCPs established and / or configured by the terminal device for other bearer types of wireless bearers, namely MN-terminated split bearers, MN-terminated SCG bearers, SN-terminated MCG bearers, SN-terminated split bearers, and SN-terminated SCG bearers, may be NR PDCP. Furthermore, when a terminal device configures NGEN-DC, NE-DC, or NR-DC, the PDCP entities that the terminal device establishes and / or configures for wireless bearers of all bearer types may be NR PDCPs.

[0103] In NR, the DRB established and / or configured by the 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 through RRC signaling received from the base station device.

[0104] Regardless of whether the terminal device configures MR-DC or not, a network configuration where the master node is eNB102 and the core network is EPC104 may be called E-UTRA / EPC. Similarly, a network configuration where the master node is eNB102 and the core network is 5GC110 may be called E-UTRA / 5GC. Furthermore, a network configuration where the master node is gNB108 and the core network is 5GC110 may be called NR or NR / 5GC. When the terminal device does not configure MR-DC, the master node mentioned above may refer to the base station device that communicates with the terminal device.

[0105] The flow of RRC signaling transmitted and received between the terminal device and the base station device will be described. Figure 4 is a diagram showing an example of the flow of procedures for various settings in the RRC according to this embodiment. Figure 4 is an example of the flow when RRC signaling is sent from the base station device (eNB102, and / or gNB108) to the terminal device (UE122).

[0106] In Figure 4, the base station device creates an RRC message (step S400). The creation of an RRC message by the base station device may be performed to distribute system information (SI) or paging messages. Alternatively, the creation of an RRC message by the base station device may be performed to send an RRC signaling to a specific terminal device to perform an action. The actions to be performed by a specific terminal device may include, for example, security settings, RRC connection reconfiguration, handover to a different RAT, suspension of an RRC connection, and release of an RRC connection. RRC connection reconfiguration may include, for example, control of radio bearers (establish, change, release, etc.), control of cell groups (establish, add, change, release, etc.), measurement settings, handover, and security key updates. The creation of an RRC message by the base station device may also be performed in response to an RRC signaling sent from a terminal device. Responses to RRC signaling transmitted from terminal devices may include, for example, responses to RRC setup requests, RRC reconnection requests, and RRC restart requests. RRC messages contain various informational notifications and configuration information (parameters). These parameters may be called fields and / or information elements and may be described using the ASN.1 (Abstract Syntax Notation One) notation scheme.

[0107] In Figure 4, the base station device then transmits the created RRC signaling to the terminal device (step S402). The terminal device then performs any necessary processing, such as configuration, according to the received RRC signaling (step S404). The terminal device that has performed the processing may transmit a response RRC signaling to the base station device (not shown).

[0108] RRC signaling may be used for purposes other than those mentioned above.

[0109] In MR-DC, the RRC signaling for SCG-side settings (cell group settings, wireless bearer settings, measurement settings, etc.) may be transmitted between the master node and the terminal device using the master node's RRC. For example, in EN-DC or NGEN-DC, the RRC signaling for NR may be included in the form of a container within the RRC signaling for E-UTRA transmitted and received between eNB102 and UE122. Similarly, in NE-DC, the RRC signaling for E-UTRA may be included in the form of a container within the RRC signaling for NR transmitted and received between gNB108 and UE122. RRC signaling for SCG-side settings may be transmitted and received between the master node and the secondary node.

[0110] Furthermore, not only when using MR-DC, 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.

[0111] Next, handover in LTE and NR will be described. Handover may be a process in which a terminal device in an RRC connection state changes the serving cell from a source SpCell to a target SpCell. Handover may be part of the mobility control performed by RRC. In a terminal device, handover may be performed based on RRC signaling that instructs handover received from a base station device. RRC signaling that instructs handover may be a message regarding the reconfiguration of the RRC connection that includes an information element (e.g., a MobilityControlInfo information element or a ReconfigurationWithSync information element) that includes a parameter that instructs handover. The MobilityControlInfo information element may be called a mobility control setting information element, mobility control setting, or mobility control information. The ReconfigurationWithSync information element may be called a synchronized reconfiguration information element. In addition to or instead of the above, the RRC signaling that indicates a handover may be a message indicating the movement of another RAT to a cell (e.g., MobilityFromEUTRACommand or MobilityFromNRCommand). The handover may be triggered by the RRC. The conditions under which a terminal device can perform a handover may also include some or all of the following conditions: AS security is activated, the terminal device has established an SRB2, and at least one DRB is established.

[0112] An example of parameters included in a message regarding the reconfiguration of an RRC connection is described below. Figure 7 is an example of an ASN.1 description representing a field and / or information element included in a message regarding the reconfiguration of an RRC connection in NR, as shown in Figure 4. Not limited to Figure 7, in the examples of ASN.1 in this embodiment, <omitted> indicates that other information is omitted, not part of the ASN.1 notation. Information elements may also be omitted where there is no <omitted> notation. In this embodiment, the example of ASN.1 represents an example of the parameters of the RRC signaling in this embodiment, and other names or notations may be used. Furthermore, in order to avoid making the explanation complicated, only examples of the main information closely related to this embodiment are shown. In each embodiment, parameters described in ASN.1 may all be expressed as information elements without distinguishing between fields, information elements, etc. Also, in each embodiment, the fields and / or information elements described in ASN.1 included in the RRC signaling may be referred to as information, or in addition to or instead referred to as parameters. The message regarding the reconfiguration of the RRC connection may be the RRC reconfiguration message in NR. Furthermore, the message regarding the reconfiguration of the RRC connection may be the RRC connection reconfiguration message in E-UTRA.

[0113] In Figure 7, the message regarding the reconfiguration of the RRC connection may include an information element used for security key updates (MasterKeyUpdate information element). The MasterKeyUpdate information element may include some or all of the following: an information element indicating whether or not to derive a new security key (keySetChangeIndicator information element), an information element indicating NCC parameters (nextHopChainingCount information element), and an information element indicating fields for transferring UE-specific NAS layer information between the network and the terminal device (nas-Container information element).

[0114] In Figure 7, the message regarding the reconfiguration of the RRC connection may include information elements (CellGroupConfig information elements) used for setting, changing, releasing, etc., of the NR's MCG or SCG cell groups. The message regarding the reconfiguration of the RRC connection may independently include CellGroupConfig information elements for MCG configuration and CellGroupConfig information elements for SCG configuration. The CellGroupConfig information elements may also be called cell group configuration information elements or cell group configurations.

[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 the RLC-BearerConfig information element as information used to configure the RLC entity.

[0117] The CellGroupConfig information element may include the MAC-CellGroupConfig information element, which is used to set the MAC parameters for that cell group.

[0118] The CellGroupConfig information element may include the PhysicalCellGroupConfig information element, which is used to set the PHY(L1) parameters specific to that cell group.

[0119] The CellGroupConfig information element may include a SpCellConfig information element, which is used to set parameters for the SpCell of that cell group. The SpCellConfig information element may also be called a SpCell setting information element or SpCell setting.

[0120] The CellGroupConfig information element may include a SCellConfig information element for each SCell, which is used to set parameters for one or more SCells in that cell group. The SCellConfig information element may also be called a SCell setting information element or SCell setting.

[0121] The MAC-CellGroupConfig information element may include a TAG-Config information element as information used to set parameters related to TAGs. The TAG-Config information element may include identifiers (TAG-Id) of one or more TAGs set by the terminal device and the value of the time adjustment timer corresponding to the identifier of that TAG.

[0122] The SpCellConfig information element may include the ServingCellConfig information element as information used to set terminal device-specific (UE specific) parameters related to SpCell. Similarly, the SCellConfig information element may include the ServingCellConfig information element as information used to set terminal device-specific (UE specific) parameters related to SCell. The CellGroupConfig information element may include a ServingCellConfig information element for each serving cell to set terminal device-specific parameters related to SpCell and each SCell. Each ServingCellConfig information element may include a TAG identifier (TAG-Id) indicating which TAG within the cell group the serving cell belongs to. In addition, the ServingCellConfig information element may include not only terminal device-specific parameters but also cell-specific parameters.

[0123] Each ServingCellConfig information element may include initialDownlinkBWP, which indicates the BWP-DownlinkDedicated information element, as a terminal device-specific setting for the initial downlink BWP. The BWP-DownlinkDedicated information element is also referred to as a downlink BWP-specific setting. In addition to or instead of this, each ServingCellConfig information element may include some or all of the first active downlink BWP identifier (firstActiveDownlinkBWP-Id), the BWP inactivity timer (bwp-InactivityTimer), and the default downlink BWP identifier (defaultDownlinkBWP-Id).

[0124] The ServingCellConfig information element, used for setting terminal device-specific parameters for each SCell, may include a DormantBWP-Config information element as a setting for a dormant BWP for the SCell. The DormantBWP-Config information element is also referred to as the dormant BWP setting. 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) that indicates whether or not SCell is activated when SCell is configured. sCellState is also referred to as the SCell state setting. For example, if the SCellConfig information element includes sCellState, or alternatively, if the RRC entity of the terminal device sets the sCellState included in the SCellConfig information element to activated, the MAC entity of the terminal device may activate the SCell, or in addition or alternatively, the RRC layer of the terminal device may configure its lower layers (MAC entity, etc.) to consider that the SCell is 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, or in addition or alternatively, the RRC layer of the terminal device may configure its lower layers (MAC entity, etc.) to consider that the SCell is deactivated.

[0126] The ServingCellConfig information element for setting terminal-specific parameters for each SCell that the terminal device has not set PUCCH may include an SCell inactivity timer.

[0127] Each ServingCellConfig information element may include an UplinkConfig information element as an uplink setting. The UplinkConfig information element is also referred to as the uplink setting. The UplinkConfig information element may include initialUplinkBWP, which indicates a BWP-UplinkDedicated information element, as a terminal device-specific setting for the initial uplink BWP. The BWP-UplinkDedicated information element is also referred to as the uplink BWP-dedicated setting. In addition to or instead of the above, the UplinkConfig information element may include a firstActiveUplinkBWP identifier (firstActiveUplinkBWP-Id).

[0128] The SpCellConfig information element may include a ReconfigurationWithSync information element, which contains information necessary for the process of synchronous reconfiguration from a source SpCell to a target SpCell. The ReconfigurationWithSync information element may be the aforementioned synchronous reconfiguration information element. If the MCG's SpCellConfig information element includes a ReconfigurationWithSync information element, the process of synchronous reconfiguration to the target SpCell may be a handover. If the SCG's SpCellConfig information element includes a ReconfigurationWithSync information element, the process of synchronous reconfiguration to the target SpCell may be a PSCell addition or PSCell modification.

[0129] The ReconfigurationWithSync information element and the SCellConfig information element may include a ServingCellConfigCommon information element, which is used to set cell-specific parameters for a serving cell. The ServingCellConfigCommon information element may include parameters typically obtained from the cell's SSB, MIB, or one or more SIBs when a terminal device accesses the cell from an idle state.

[0130] The ReconfigurationWithSync information element may include, for example, information on the C-RNTI value used in the cell group of the target SpCell. The ReconfigurationWithSync information element may also include, for example, information on the parameters of timer T304, as described later. The ReconfigurationWithSync information element may also include the RACH-ConfigDedicated information element, for example, information necessary 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 the RACH-dedicated setting.

[0131] Figure 8 is an example of an ASN.1 description representing the fields and / or information elements related to the ServingCellConfigCommon information element, which are included in the SCellConfig information element and the ReconfigurationWithSync information element within the SpCellConfig information element, as shown in Figure 7.

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

[0133] The ServingCellConfigCommon information element may include a DownlinkConfigCommon information element, which provides cell-specific (cell-common) downlink parameters. The DownlinkConfigCommon information element is also referred to as the common downlink setting.

[0134] The ServingCellConfigCommon information element may include the UplinkConfigCommon information element, which provides cell-specific (cell-common) uplink parameters. The UplinkConfigCommon information element is also referred to as the common uplink setting.

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

[0136] The DownlinkConfigCommon information element may include the FrequencyInfoDL information element as basic information about the downlink carrier and transmission on that downlink carrier. For example, the FrequencyInfoDL information element may include SSB frequency information.

[0137] The DownlinkConfigCommon information element may include initialDownlinkBWP, which indicates the BWP-DownlinkCommon information element, as the initial downlink BWP setting for that cell. In addition to or instead of this, the DownlinkConfigCommon information element may include initialDownlinkBWP-RedCap, which indicates the BWP-DownlinkCommon information element used by one or more performance-limited terminals (RedCap UEs) instead of initialDownlinkBWP. The BWP-DownlinkCommon information element is also referred to as the common downlink BWP setting.

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

[0139] The BWP-DownlinkCommon information element may include the PDCCH-ConfigCommon information element, which provides information for the terminal device to set cell-specific parameters for the PDCCH of this BWP. The PDCCH-ConfigCommon information element is also referred to as the PDCCH common settings.

[0140] The BWP-DownlinkCommon information element may include the PDSCH-ConfigCommon information element, which provides information for the terminal device to set cell-specific parameters for the PDSCH of this BWP. The PDSCH-ConfigCommon information element is also referred to as the PDSCH common settings.

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

[0142] The PDCCH-ConfigCommon information element may include a ControlResourceSetZero information element as information for a terminal device to set the parameters of the common CORESET#0 used in one or more common search spaces and one or more UE-specific search spaces. This ControlResourceSetZero information element may be included in the PDCCH-ConfigCommon information element only if the BWP is the initial downlink BWP.

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

[0144] The PDCCH-ConfigCommon information element may contain a list of information elements (SearchSpace information elements) (commonSearchSpaceList) that indicate one or more additional CSS settings.

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

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

[0147] The PDCCH-ConfigCommon information element may include information (pagingSearchSpace) indicating which CSS setting in commonSearchSpaceList is responsible for setting the search space for paging messages.

[0148] The UplinkConfigCommon information element may include the FrequencyInfoUL information element, which sets the absolute uplink frequency and lists multiple virtual carriers specific to each subcarrier. For example, the FrequencyInfoUL information element may include information indicating the maximum transmit power.

[0149] The UplinkConfigCommon information element may include initialUplinkBWP, which indicates the BWP-UplinkCommon information element, as the initial uplink BWP setting for that cell. In addition to or instead of this, the UplinkConfigCommon information element may include initialUplinkBWP-RedCap, which indicates the BWP-UplinkCommon information element used by one or more performance-limited terminals (RedCap UEs) instead of initialUplinkBWP. The BWP-UplinkCommon information element is also referred to as the common uplink BWP setting.

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

[0151] The BWP-UplinkCommon information element may include the PUCCH-ConfigCommon information element, which provides information for the terminal device to set cell-specific parameters for PUCCH of this BWP. The PUCCH-ConfigCommon information element is also referred to as the PUCCH common settings.

[0152] The BWP-UplinkCommon information element may include the PUSCH-ConfigCommon information element, which provides information for the terminal device to set cell-specific parameters for the BWP's PUSCH function. The PUSCH-ConfigCommon information element is also referred to as the PUSCH common settings.

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

[0154] Note that each of the above information elements may include other information besides the information described.

[0155] This document describes the RRC reconfiguration procedure. The RRC reconfiguration procedure is a procedure for a terminal device to modify an RRC connection based on a message regarding the 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 wireless bearer; (B) Performing a synchronized reconfiguration; (C) Setting up, modifying, and / or releasing a measurement; (D) Adding, modifying, and / or releasing SCells and cell groups; (E) Adding, modifying, and / or releasing a conditional handover (CHO) setting; (F) Adding, modifying, and / or releasing a conditional PSCell change (CPC) or conditional PSCell addition (CPA) setting.

[0156] The base station equipment (Network) may initiate the RRC reconfiguration procedure for a terminal device in the RRC_CONNECTED state. Note that "the base station equipment initiates the RRC reconfiguration procedure for a terminal device" can be rephrased as "the base station equipment sends a message to the terminal device regarding the reconfiguration of the RRC connection."

[0157] When a terminal device receives a message regarding the resetting of an RRC connection, or when performing a conditional reset (CHO, CPA, or CPC), it may perform some or all of the following RRP processes (A) through (D): (RRP processes) (A) If the message regarding the resetting of an RRC connection includes an MCG cell group setting, the cell group setting is performed using that cell group setting. In addition, if the cell group setting includes a SpCell setting that includes a synchronized reset information element, a synchronized reset is performed. (B) If the message regarding the resetting of an RRC connection includes an SCG cell group setting, the cell group setting is performed using that cell group setting. In addition, if the cell group setting includes a SpCell setting that includes a synchronized reset information element, a synchronized reset is performed. (C) If the message regarding the resetting of an RRC connection includes information about a conditional reset, the conditional reset setting process is performed using that conditional reset information. (D) To transmit using the new settings, an RRC reconfiguration completion message is submitted to the lower layers of the terminal device (PHY, MAC, etc.).

[0158] The terminal device may perform some or all of the following RWS processes (A) through (G) in order to execute synchronized reset. "Execute synchronized reset" may be rephrased as "Perform synchronized reset" or "Trigger synchronized reset". (RWS Process) (A) If this procedure is performed for an MCG, or if this procedure is performed for an SCG that has not been notified of deactivation in the RRC signaling of an E-UTRA or NR embedded in a message regarding the reset of the RRC connection, set the value of the timer T304 described below included in the synchronized reset information element and start the timer T304 for the corresponding SpCell. (B) If the synchronized reset information element includes a frequencyInfoDL information element, determine that the target SpCell is the cell indicated by the physical cell identifier included in the synchronized reset information element, which is at the SSB frequency indicated by the frequencyInfoDL information element. If the synchronized reset information element does not contain the frequencyInfoDL information element, it is determined that the target SpCell is a cell that is on the same SSB frequency as the source SpCell and is indicated by the physical cell identifier included in the synchronized reset information element. (C) Start downlink synchronization to the target SpCell. (D) If the timing information required for the random access procedure is not held, retrieve the MIB of the target SpCell. (E) Reset the MAC entity of the cell group to be reset with synchronization. (F) Apply the value of the new UE identifier (newUE-Identity) included in the synchronized reset information element as the C-RNTI for the cell group to be reset with synchronization. (G) Configure the lower layers of the RRC (PHY, etc.) according to the SpCell common settings.

[0159] Conditional reconfiguration is described below. The terminal device receives one or more conditional reconfiguration information elements from the network, and therefore, the terminal device sets candidate target SpCells associated with each conditional reconfiguration information element received from the network. The terminal device evaluates the state of the set candidate target SpCells. The terminal device performs the evaluation and applies one of the conditional RRC reconfiguration information elements included in the conditional reconfiguration information elements associated with one or more candidate target SpCells that satisfy the execution conditions. The terminal device may also maintain a list of entries (VarConditionalReconfig) described later for conditional reconfiguration.

[0160] Conditional resetting may be referred to as conditional handover when the candidate target SpCell is an MCG SpCell (i.e., a PCell). Alternatively, conditional resetting may be referred to as conditional PSCell addition and / or conditional PSCell modification when the candidate target SpCell is an SCG SpCell (i.e., a PSCell).

[0161] As part of the conditional reset configuration process, the terminal device may, upon receiving information regarding conditional resets (e.g., conditional reset information elements), perform a conditional reset if the information regarding conditional resets includes an attempt conditional reset information element (attemptCondReconfig), and if the selected cell in the RRC connection re-establishment procedure described later is a target candidate cell (e.g., candidate target SpCell) and the cell selection is the first cell selection after a conditional reset failure (e.g., expiration of timer T304).

[0162] As part of the conditional reset setting process, if the information regarding the conditional reset includes an entry deletion list (condReconfigToRemoveList), the terminal device may remove the conditional reset setting specified in the entry deletion list from the settings held by the terminal device. 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.

[0163] In the following explanation, the list of conditional reset entries held by the terminal device will also be simply referred to as the entry list. That is, unless otherwise specified, "entry list" in the following explanation refers to the list of conditional reset entries held by the terminal device. The conditional reset entry list may also be a variable named VarConditionalReconfig. The entry identifier will also be simply referred to as the entry identifier.

[0164] As part of the conditional reset configuration process, if the information regarding the conditional reset includes an entry addition / modification list (condReconfigToAddModList), the terminal device may add or modify the conditional reset settings included in the entry addition / modification list to the settings held by the terminal device. The entry addition / modification list may be a list of one or more conditional reset information elements. The terminal device may configure each entry with a conditional reset information element. The conditional reset information element may include an entry identifier, an execution condition, and a conditional RRC reset information element.

[0165] Specifically, if each entry identifier included in the entry addition / modification list exists in an entry in the entry list, the terminal device may perform the following processes (A) and / or (B): (A) If an entry included in the entry addition / modification list includes an execution condition (condExecutionCond), the execution condition of the entry in the entry list that matches the entry identifier of this entry is replaced with the execution condition included in the entry addition / modification list. (B) If an entry included in the entry addition / modification list includes a conditional RRC reconfiguration information element (condRRCReconfig), the conditional RRC reconfiguration information element of the entry list that matches the entry identifier of this entry is replaced with the conditional RRC reconfiguration information element included in the entry addition / modification list.

[0166] 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 to the entry list corresponding to the entry identifier that is not included in the entry list.

[0167] 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 may include an entry identifier, and in addition, may include execution conditions and / or conditional RRC reset information elements. Each entry may be associated with one of one or more candidate target SpCells. The entry identifier may be an identifier used to identify each entry of CHO, CPA, and CPC. The entry list may include one or more entries. Each entry may include one entry identifier, one or more execution conditions, and one conditional RRC reset information element. If the entry list held by the terminal device does not contain any entries, the terminal device may hold an empty list. The execution conditions may be conditions that must be met to trigger the execution of conditional reset. The conditional RRC reset information elements may be messages regarding the reset of the RRC connection that are applied when the execution conditions are met. The messages regarding the reset of the RRC connection may be messages used to connect to a candidate target SpCell.

[0168] A terminal device may evaluate the execution conditions of entries included in the entry list it holds. If the entry list held by the terminal device is empty or if it does not hold an entry list, it does not need to evaluate the execution conditions.

[0169] Conditional resetting may be performed by a terminal device evaluating the execution conditions of an entry in the entry list it holds, and if one or more execution conditions are met, applying a conditional RRC resetting information element contained in the entry containing those execution conditions. Applying a conditional RRC resetting information element may be performed by using that conditional RRC resetting information element to execute an RRC resetting procedure.

[0170] If there are multiple entries that satisfy the execution conditions, the terminal device may select one entry from among the multiple entries that satisfy the execution conditions and apply the conditional RRC reset information element of the selected entry.

[0171] If a MAC entity of a terminal device is requested to reset the MAC entity from a higher layer (e.g., RRC), it may perform some or all of the following processes MR (A) through (N). The MAC entity reset may simply be referred to as a MAC reset. If a MAC entity of a terminal device is requested to partially reset the MAC entity from a higher layer (e.g., RRC), it may perform some or all of the following processes MR (A) through (N). The partial reset of the MAC entity may simply be 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 a 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. In addition to or instead of the above, the MAC entity of the terminal device may perform a partial MAC reset based on an instruction from the RRC entity of the terminal device to the MAC entity of the terminal device.

[0172] (Processing MR) (A) Initialize parameter Bj set by the terminal device for each logical channel to 0. (B) Stop all running timers except for some timers, including time adjustment timers. (C) Set the value of New Data Indicator (NDI) for all uplink HARQ processes to 0. (D) Stop any ongoing random access procedures. (E) Discard any explicitly signaled 4-step and 2-step RA type contention-free random access (CFRA) resources. (F) Flush the Msg3 buffer. (G) Flush the MSGA buffer. (H) Cancel any triggered Scheduling Request (SR) procedures. (I) Cancel any triggered Buffer Status Reporting (BSR) procedures. (J) Cancel any triggered Power Headroom Reporting (PHR) procedures. (K) Flushes the soft buffers of all downlink HARQ processes. (L) Cancels any triggered Beam Failure Reporting (BFRs). (M) Releases any Temporary C-RNTIs. (N) Resets all BFI_COUNTERs.

[0173] This section describes the RRC connection re-establishment procedure. The RRC connection re-establishment procedure is 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 called the RRC re-establishment procedure. In the RRC connection re-establishment procedure, the terminal device may send an RRC re-establishment request message to the base station device (Network), and then, based on receiving an RRC re-establishment message from the base station device, determine that the RRC connection has been successfully re-established and send an RRC re-establishment complete message to the base station device. The order in which the terminal device determines that the RRC connection has been successfully re-established and sends the RRC re-establishment complete message to the base station device does not matter. Furthermore, a terminal device in the RRC_CONNECTED state may start the procedure in order to continue the RRC connection. Re-establishing the RRC connection is successful if the base station device can find a valid UE context and verify that it is the UE context held by the terminal device. Alternatively, if the UE context cannot be obtained, the base station device may respond with an RRC setup message.

[0174] When the terminal device initiates the RRC connection re-establishment procedure, it may perform some or all of the following RRI processes (A) to (C). (RRI processes) (A) Stop timer T304 if it is running. (B) If the terminal device has not set the attemptCondReconfig element, perform some or all of the following processes (B-1) to (B-5). (C) Perform cell selection, and if a suitable NR cell is selected, perform some or all of the following processes (C-1) to (C-2).

[0175] (B-1) Reset the MAC entity. (B-2) Release the SpCell configuration if configured by the terminal device. (B-3) Suspend all wireless bearers except SRB0. (B-4) Release one or more SCells of the MCG if configured by the terminal device. (B-5) Release the MR-DC if configured by the terminal device.

[0176] (C-1) Ensure that you have valid, up-to-date, and essential system information. (C-2) If cell selection is triggered by detection of MCG wireless link failure, MCG synchronous reconfiguration failure (i.e., expiration of timer T304), or mobility failure from NR, and the terminal device has set an attempt conditional reconfiguration information element (attemptCondReconfig), and the selected cell is one of the candidate cells for a synchronous reconfiguration information element included in the MCG conditional reconfiguration entry list (VarConditionalReconfig), then the terminal device applies the conditional RRC reconfiguration information element (condRRCReconfig) associated with the selected cell and performs some or all of the above-described RRP process; otherwise, some or all of the following processes (C-2-1) to (C-2-4) are performed; if the terminal device has set an attempt conditional reconfiguration information element (attemptCondReconfig), then some or all of the following processes (C-2-5) to (C-2-7) are performed.

[0177] (C-2-1) Apply the (multiple) default L1 parameter values ​​other than those provided in SIB1 as the values ​​for the corresponding physical layer specifications. (C-2-2) Apply the default MAC cell group configuration. (C-2-3) Apply the CCCH configuration. (C-2-4) Start sending the RRC re-establishment request message.

[0178] (C-2-5) Reset the MAC entity. (C-2-6) Release the SpCell configuration if the terminal device has configured it. (C-2-7) Release one or more SCells of the MCG if the terminal device has configured it.

[0179] The timer T304 described above may start when the terminal device receives a message regarding the reconfiguration of the RRC connection, which includes a synchronized reconfiguration information element, and may stop when the random access procedure on the SpCell corresponding to the synchronized reconfiguration information element is successfully completed. Also, when the timer T304 described above expires, the terminal device may start the RRC connection re-establishment procedure. In addition to or instead of this, the timer T304 described above may start when a lower layer (such as the MAC layer) notifies that the LTM cell switching process described below has been triggered, and / or when the LTM cell switching process is performed after cell selection. In addition to or instead of this, in the case of an LTM cell switching that does not involve the execution of a random access procedure, the timer T304 described above may stop for the same HARQ process when a PDCCH addressed to C-RNTI is received after the initial uplink transmission.

[0180] Next, we will describe the Central Unit (CU) and the Distributed Unit (DU). A Central Unit may be a logical node that hosts the RRC, SDAP, and PDCP layers of a base station device. A Distributed Unit may be a logical node that hosts the RLC, MAC, and PHY layers of a base station device. A Central Unit may control the operation of one or more Distributed Units. A single Distributed Unit may support one or more cells. A single cell may be supported by only one Distributed Unit. Some functions of the Central Unit may be implemented in the Distributed Units. Conversely, some functions of the Distributed Units may be implemented in the Central Units.

[0181] Next, Layer 1 / Layer 2 triggered mobility (L1 / L2-triggered mobility: LTM) in this embodiment will be described.

[0182] LTM may be a procedure in which the base station device switches the serving cell of a terminal device by a cell switching command signaled via MAC CE, based on one or more L1 measurement reports received by the base station device from the terminal device. The cell switching command specifies an LTM candidate setting that the base station device has prepared in advance and provided to the terminal device via RRC signaling. The terminal device may apply a target setting in accordance with the cell switching command.

[0183] For example, the RRC layer of the terminal device may receive RRC signaling from the base station device, which includes one or more LTM candidate settings. The RRC layer of the terminal device may store the received one or more LTM candidate information elements. The MAC layer of the terminal device may also receive a cell switching command from the base station device via MAC CE. The RRC layer of the terminal device may apply a target setting in accordance with the cell switching command. The cell switching command may include a target setting identifier indicating the target setting. The MAC layer of the terminal device that has received the cell switching command may notify the RRC layer of the terminal device (a layer higher than the MAC layer) that the LTM cell switching procedure has been triggered and the target setting identifier. The RRC layer that has received notification from the MAC layer (a layer lower than the RRC layer) that the LTM cell switching procedure has been triggered and the target setting identifier may trigger the cell switching procedure and apply one of the one or more LTM candidate information elements identified by the target identifier. The target setting identifier may be an identifier used to identify a candidate LTM setting. The target setting may be a candidate LTM setting indicated by the target setting identifier. The cell switching command may be a command (MAC CE) that triggers the terminal device to perform an LTM cell switching procedure. The target identifier may be associated with a candidate LTM identifier described later.

[0184] In LTM, the base station equipment may determine the target setting based on a measurement report provided by the terminal equipment. The measurement report may be a CSI reporting transmitted by the terminal equipment via PUSCH. In addition to or instead, the measurement report may be a CSI reporting transmitted by the terminal equipment via PUCCH. In addition to or instead, the measurement report may be a measurement report message transmitted by the terminal equipment as RRC signaling. In addition to or instead, the measurement report may be measurement report information transmitted by the terminal equipment as MAC CE. The measurement report may also be other information.

[0185] MAC CE can also be referred to as Layer 2 signaling. Furthermore, the above measurements may be performed by Layer 1 (PHY layer), Layer 2 (MAC layer), and / or Layer 3 (RRC layer). Furthermore, the above measurement reports may be performed by Layer 1 (PHY layer), Layer 2 (MAC layer), and / or Layer 3 (RRC layer).

[0186] The cell switching command may be signaled by MAC CE. The MAC CE may also be called the LTM cell switching command MAC CE and may be used interchangeably with the term cell switching command. That is, sending and receiving a cell switching command may be rephrased as sending and receiving an LTM cell switching command MAC CE. The cell switching command may include multiple fields, and these multiple fields may include the following information, as well as other information: (a) a target setting identifier corresponding to the LTM candidate identifier (b) a TA command (c) an identifier indicating the TCI state in the target setting SpCell (target cell) (d) an identifier indicating the uplink TCI state in the target setting SpCell (target cell) (e) information indicating the existence of a CFRA resource (f) information indicating the uplink carrier that transmits the CFRA PRACH (g) a preamble index of the CFRA resource (h) information indicating the SSB used to determine the RACH occasion for transmitting the CFRA PRACH (i) information indicating the RACH occasion related to the SSB indicated in the information indicating the SSB

[0187] One or more LTM candidate information elements may be included in the LTM setting, and the LTM setting may be included in the RRC reset message. The RRC reset message may be RRC signaling. The LTM candidate information elements may include an LTM candidate identifier, an LTM candidate cell identifier, an LTM-SSB setting, an LTM candidate setting, an LTM full setting indicator, an early UL synchronization setting, an early SUL synchronization setting, an LTM reset decision identifier B, an LTM-UE reference TA measurement identifier B, and other information. The LTM candidate identifier is an identifier used to identify the LTM candidate setting and the LTM candidate information elements, and may be an information element named ltm-CandidateId. The LTM candidate cell identifier is an identifier indicating the physical cell identifier (PCI) of the SpCell of the setting included in the LTM candidate setting, and may be an information element named ltm-CandidatePCI. The LTM-SSB setting indicates the setting of the SS / PBCH block used for L1 measurement and TCI status, and may be an information element named ltm-SSB-Config. The LTM candidate setting is a setting that includes RRC resetting used to set up an LTM candidate cell, and may be an information element named ltm-CandidateConfig. The LTM complete setting indicator indicates whether the RRC resetting included in the LTM candidate setting is a complete setting, and may be an information element named ltm-ConfigComplete. The early UL synchronization setting is a setting used to execute an early UL synchronization procedure on the UL carrier, and may be an information element named ltm-EarlyUL-SyncConfig. The early SUL synchronization setting is a setting used to execute an early UL synchronization procedure on the SUL carrier, and may be an information element named ltm-EarlyUL-SyncConfigSUL. The LTM reset determination identifier B is an identifier used to determine whether an L2 reset is performed when an LTM cell switching procedure is triggered for an LTM candidate cell, and may be an information element named ltm-NoResetID.The LTM-UE criterion TA measurement identifier B is an identifier used to determine whether or not to perform a UE criterion TA measurement on an LTM candidate cell, and may be an information element named ltm-UE-MeasuredTA-ID.

[0188] The LTM configuration may include an LTM reference configuration, an LTM candidate configuration release list, an LTM candidate configuration add / modify list, an LTM reset decision identifier A, an LTM-UE criterion TA measurement identifier A, an LTM-CSI resource configuration release list, an LTM-CSI resource configuration add / modify list, and other information. The LTM reference configuration is a configuration used to configure a reference configuration for LTM, and may be an information element named ltm-ReferenceConfiguration. The LTM candidate configuration release list is a list indicating LTM candidate configurations to be released, and may be an information element named ltm-CandidateToReleaseList. The LTM candidate configuration release list may be a list of LTM candidate identifiers corresponding to the LTM candidate configurations to be released. The LTM candidate configuration add / modify list is a list of LTM candidate configurations to be added and / or modified, and may be an information element named ltm-CandidateToAddModList. The LTM reset decision identifier A is an identifier used to determine whether an L2 reset is performed when an LTM cell switching procedure is triggered for an LTM candidate cell, and may be an information element named ltm-ServingCellNoResetID. The LTM-UE-based TA measurement identifier A is an identifier used to determine whether or not to perform a UE-based TA measurement on an LTM candidate cell, and may be an information element named ltm-ServingCellUE-MeasuredTA-ID. The LTM-CSI resource configuration release list is a list indicating the LTM-CSI resource configurations to be released, and may be an information element named ltm-CSI-ResourceConfigToReleaseList. The LTM-CSI resource configuration release list may be a list of LTM-CSI resource configuration identifiers corresponding to the LTM-CSI resource configurations to be released. The LTM-CSI resource configuration add / modify list is a list of LTM-CSI resource configurations to be added and / or modified, and may be an information element named ltm-CSI-ResourceConfigToAddModList.An LTM-CSI resource configuration may be a configuration that defines a group of one or more CSI resources for one or more LTM candidate configurations. Each LTM-CSI resource configuration may be identified by an LTM-CSI resource configuration identifier.

[0189] A terminal device that has received an RRC reset message including an LTM setting may perform the following actions based on the received LTM setting: (A) If the received LTM setting includes an LTM reset decision identifier A, and the current UE variable-LTM reset decision identifier includes an LTM reset decision identifier A, the terminal device may replace the value of the LTM reset decision identifier A included in the UE variable-LTM reset decision identifier with the received LTM reset decision identifier A; or, if the received LTM setting includes an LTM reset decision identifier A, and the current UE variable-LTM reset decision identifier does not include an LTM reset decision identifier A, the terminal device may store the received LTM reset decision identifier A in the UE variable-LTM reset decision identifier. (B) If the received LTM setting includes LTM-UE reference TA measurement identifier A, and the current UE variable-LTM-UE reference TA measurement identifier includes LTM-UE reference TA measurement identifier A, the value of LTM-UE reference TA measurement identifier A included in the UE variable-LTM-UE reference TA measurement identifier may be replaced with the received LTM-UE reference TA measurement identifier A. If the received LTM setting includes LTM-UE reference TA measurement identifier A, and the current UE variable-LTM-UE reference TA measurement identifier does not include LTM-UE reference TA measurement identifier A, the received LTM-UE reference TA measurement identifier A may be stored in the UE variable-LTM-UE reference TA measurement identifier. (C) If the received LTM setting includes an LTM candidate setting release list, the terminal device that received the LTM candidate setting release list described below may be operated. (D) If the received LTM setting includes an LTM candidate setting addition / modification list, the terminal device that received the LTM candidate setting addition / modification list described below may be operated. The aforementioned UE variable -LTM reset determination identifier may be used to store the identifier of a serving cell, which serves as a criterion for the terminal device to determine whether or not an L2 reset is necessary during the LTM cell switching procedure. This UE variable may be named VarLTM-ServingCellNoResetID.The aforementioned UE variable-LTM-UE reference TA measurement identifier may be used to store the identifier of a serving cell that serves as the criterion for the terminal device to determine whether or not UE reference TA measurement is necessary, and may be a UE variable named VarLTM-ServingCellUE-MeasuredTA-ID. Note that a UE variable may be a variable stored internally in the terminal device.

[0190] A terminal device that has received the LTM candidate setting addition / modification list performs the following processing for each LTM candidate identifier included in the LTM candidate setting addition / modification list: (A) If it determines that the current settings of the terminal device include an LTM candidate information element containing an LTM candidate identifier with the same value as the LTM candidate identifier, it resets the corresponding LTM candidate information element (included in the terminal device settings) according to the received LTM candidate information element. Otherwise (i.e., it does not determine that the current settings of the terminal device include an LTM candidate information element containing an LTM candidate identifier with the same value as the LTM candidate identifier), it may add the received LTM candidate information element to the settings of the terminal device. (B) If the LTM candidate information element containing the received LTM candidate identifier contains the LTM-UE criterion TA measurement identifier B, and further, (C) if it is determined that the value of the LTM-UE criterion TA measurement identifier B is equal to the value of the LTM-UE criterion TA measurement identifier A contained in the UE variable-LTM-UE criterion TA measurement identifier, the lower layer may be notified that a UE criterion TA measurement is set up for this LTM candidate information element. If not (i.e., if it is not determined that the value of the LTM-UE criterion TA measurement identifier B is equal to the value of the LTM-UE criterion TA measurement identifier A contained in the UE variable-LTM-UE criterion TA measurement identifier), the lower layer may be notified that a UE criterion TA measurement is not set up for this LTM candidate information element.

[0191] Upon receiving the LTM candidate setting release list, the terminal device performs the following processing on each LTM candidate identifier included in the LTM candidate setting release list: (A) It may delete the LTM candidate information element corresponding to the LTM candidate identifier.

[0192] Furthermore, if NR-DC is configured on the terminal device, the terminal device can receive two independent LTM settings. That is, it can receive (1) an LTM setting associated with the MCG contained in an RRC reset message received via SRB1, and (2) an LTM setting associated with the SCG contained in an RRC reset message received via SRB3 or embedded in an RRC reset message received via SRB1. If the terminal device receives two independent LTM settings, the terminal device may maintain the two independent LTM settings, maintain two independent UE variable-LTM-UE reference TA measurement identifiers, maintain two independent UE variable-LTM reset decision identifiers, and perform all procedures independently for each LTM setting, UE variable-LTM-UE reference TA measurement identifier and UE variable-LTM reset decision identifier unless otherwise explicitly instructed.

[0193] In LTM, some or all of the following mobility scenarios (A) through (J) may be supported, and other mobility scenarios may also be supported: (A) Intra-gNB-DU mobility (B) Intra-gNB-CU inter-gNB-DU mobility (C) Inter-frequency mobility (including mobility to inter-frequency cells that are not the current serving cell) (D) Intra-frequency mobility (E) PCell changes in terminal equipment where CA and DC are not configured (F) PCell and one or more SCell changes in terminal equipment where CA is configured (G) PCell and MCG SCell(s), PSCell and SCG SCell(s) changes, MN-independent changes in terminal equipment where DC is configured (H) Inter-cell beam management (not considered as a prerequisite for using Layer 1 / Layer 2 triggered mobility) (I) Inter-gNB-CU mobility (J) Conditional mobility

[0194] This section describes a random access procedure initiated by a PDCCH order. A random access procedure initiated by a PDCCH order may be a random access procedure that includes a procedure in which the identifier of the random access preamble is explicitly provided by the PDCCH order (PDCCH). The identifier of the random access preamble may be a 6-bit identifier named, for example, ra-PreambleIndex. The identifier of the random access preamble may be indicated by the RACH-ConfigDedicated information element described above. The PDCCH order may be a PDCCH that sends a DCI for scheduling a PDSCH within a single downlink cell, for example, named DCI format 1_0. In addition to or instead of the above, the PDCCH order and / or the DCI format 1_0 may include an SS / PBCH (SSB) identifier (SS / PBCH block index field) used to determine the RACH occasion for PRACH transmission (PRACH occasion) if the values ​​of the identifiers in the random access preamble are not all zero, and / or a PRACH mask identifier (PRACH mask index field) indicating the RACH occasion associated with the SS / PBCH. In the following description, "random access preamble" and "PRACH" may be used interchangeably.

[0195] If a random access procedure is initiated on a serving cell by a PDCCH order, the terminal device may send a PRACH on that serving cell. For example, if a random access procedure is initiated on a PCell by a PDCCH order, the terminal device may send a PRACH on that PCell. In addition to or instead of the above, for example, if a random access procedure is initiated on a SCell by a PDCCH order, the terminal device may send a PRACH on that SCell. Note that "if a random access procedure is initiated on a serving cell by a PDCCH order" may be rephrased as "if the terminal device receives a PDCCH (PDCCH order) on a serving cell that explicitly provides an identifier for a random access preamble," etc.

[0196] In a random access procedure of RA type 4 steps, if the identifier of the random access preamble is explicitly provided by the PDCCH, the MAC entity of the terminal device may perform (a) and / or (b) below, provided that the values ​​of the identifier of the random access preamble are not all zero: (a) Set the preamble identifier (PREAMBLE_INDEX) to the value of the signaled random access preamble identifier; (b) Select the SSB signaled by the PDCCH.

[0197] In a random access procedure of type 4 steps, the MAC entity of the terminal device may compute a random access identifier (RA-RNTI) associated with the PRACH occasion to which the random access preamble is sent, and instruct the PHY layer to send the random access preamble using the selected PRACH occasion, the corresponding random access identifier (RA-RNTI), and / or the identifier of the preamble. The PHY layer of the terminal device may send a PRACH within the selected PRACH occasion if a request for sending a random access preamble is received from a higher layer (such as the MAC entity). At this time, the time between the last symbol that receives the PDCCH order and the first symbol that sends the PRACH may be longer than N_{T,2} + Δ_BWPSwitching + Δ_Delay + T_switch milliseconds (msec), or equal to N_T,2 + Δ_BWPSwitching + Δ_Delay + T_switch milliseconds. Here, N_{T,2} may be the time interval of the N_2 symbol corresponding to the PUSCH preparation time. In addition or alternatively, Δ_BWPSwitching may be the delay that occurs during BWP switching, and the value of Δ_BWPSwitching may be 0 if the Active UL BWP is not changed. In addition 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) and 0.25 milliseconds (msec) in the frequency range 24250 MHz - 52600 MHz (Frequency range 2: FR2, or Frequency range 2-1: FR2-1). In addition or alternatively, T_switch may be the switching gap duration.

[0198] Once a random access preamble has been sent, regardless of the potential occurrence of a measurement gap, the MAC entity of the terminal device may, in the first PDCCH occasion, start a random access response window (ra-ResponseWindow) set by the RRC entity of the terminal device in the RACH-ConfigCommon information element, and while the random access response window is running, monitor the SpCell's PDCCH for one or more random access responses (RARs) identified by a random access identifier (RA-RNTI). The MAC entity of the terminal device may consider the reception of the random access response to have been successful if it has received a valid downlink assignment in the PDCCH for a random access identifier (RA-RNTI), has successfully decoded the received transport block (TB), and the received random access response contains a MAC subPDU with a random access preamble identifier corresponding to the transmitted PREAMBLE_INDEX.

[0199] A MAC entity of a terminal device that has received a random access response and deemed it to have been successful will consider the random access procedure to have been completed successfully if the received random access response contains only MAC subPDUs with RAPID, and will indicate to the higher layer (RRC layer, etc.) that it has received an acknowledgment for the SI request. Otherwise (if the received random access response contains MAC subPDUs with RAPID and MAC RARs), some or all of the following actions (a) to (c) may be applied to the serving cell that sent the random access preamble. Note that the MAC RAR mentioned above may include some or all of the Timing Advance Command (TAC), uplink grants, and / or Temporary C-RNTIs described below. (a) Process the Timing Advance Command described below. (b) The base station equipment notifies lower layers (PHY layer, etc.) of the parameter for the received power (target power) of the random access preamble (preambleReceivedTargetPower) and the amount of power ramping applied when the random access preamble was last transmitted. (c) If a random access procedure for SCell is performed on an uplink carrier where the terminal equipment has not set terminal equipment-specific PUSCH parameters (UE-specific PUSCH parameter: PUSCH-Config), the received uplink grant is ignored; otherwise, the value of the received uplink grant is processed and that value is notified to lower layers (PHY layer, etc.).

[0200] The terminal device may adjust the transmission timing of the uplink. For example, the terminal device may adjust the transmission timing of the uplink based on the reception of a Timing Advance Command (TAC) MAC CE. A group of serving cells set up by the terminal device in RRC, in which serving cells use the same timing reference cell and the same timing advance value for the cell on which the terminal device sets the uplink, may be called a Timing Advance Group (TAG). A TAG containing a MAC entity SpCell may be referred to as a Primary Timing Advance Group (PTAG). TAGs other than the PTAG may be referred to as Secondary Timing Advance Groups (STAG). One or more of the above TAGs may be configured independently for each cell group.

[0201] For example, upon receiving a TAC MAC CE for a given TAG, the terminal device may adjust the uplink transmission timing for PUSCH, SRS, and / or PUCCH transmissions in some or all serving cells in that TAG. The terminal device may adjust the uplink transmission timing so that T_TA is earlier than the timing of the beginning of the downlink frame of the same frame number. The terminal device may calculate the timing advance value T_TA based on N_TA and the TA offset (N_{TA,offset}). The terminal device may set N_TA based on information contained 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 take the same value for serving cells in the same TAG.

[0202] Furthermore, in Dual Connectivity, cells in each cell group may belong to different TAGs. That is, the PTAG of the MCG and the PTAG of the SCG may be independent and different TAGs.

[0203] The RRC entity of a terminal device may set the value of the timeAlignmentTimer to MAC in order to maintain time alignment of the uplink. The timeAlignmentTimer may be used to control the amount of time that the MAC entity considers to be aligned on the uplink of a serving cell belonging to the TAG associated with the timeAlignmentTimer. The terminal device may set the value of the timeAlignmentTimer using RRC signaling received from the base station device.

[0204] The MAC entity of the terminal device may apply the Timing Advance Command (TAC) to the TAG specified by the TAC MAC CE, based on the fact that it has received the Timing Advance Command (TAC) MAC CE and that the N_TA of the TAG specified by the TAC MAC CE is maintained. Furthermore, the MAC of the terminal device may start, or restart, the timeAlignmentTimer associated with the TAG specified by the TAC MAC CE, based on the fact that it has received the Timing Advance Command (TAC) MAC CE and that the N_TA of the TAG specified by the TAC MAC CE is maintained.

[0205] A MAC entity of a terminal device may apply a Timing Advance Command (TAC) to a TAG based on the fact that it received a Timing Advance Command (TAC) in a Random Access Response (RAR) message for a serving cell belonging to a TAG, and that the random access preamble was not selected by the MAC entity from among contention-based random access preambles (for example, the identifier of the random access preamble was explicitly provided by PDCCH order). In addition to or instead of this, the MAC entity of the terminal device may start, or restart, a timeAlignmentTimer, associated with a TAG based on the fact that it received a Timing Advance Command (TAC) in a Random Access Response (RAR) message for a serving cell belonging to a TAG, and that the random access preamble was not selected by the MAC entity from among contention-based random access preambles.

[0206] When the MAC entity of a terminal device has expired the time adjustment timer associated with a PTAG, it may perform some or all of the following actions (A) through (G): (A) Flush all HARQ buffers for all serving cells (in the cell group). (B) If the terminal device has set up PUCCH, notify the RRC that it has released PUCCH for all serving cells. (C) If the terminal device has set up SRS, notify the RRC that it has released SRS for all serving cells. (D) Clear all configured downlink assignments and configured uplink grants. (E) Clear all PUSCH for semi-persistent CSI reporting. (F) Assume that all time adjustment timers, including STAGs, have expired. (G) Maintain N_TA for all TAGs.

[0207] When the MAC entity of a terminal device has finished the time adjustment timer associated with a STAG, it may perform some or all of the following actions (A) through (F) for all serving cells belonging to this STAG: (A) Flush all HARQ buffers. (B) If the terminal device has set up PUCCH, notify RRC that PUCCH has been released. (C) If the terminal device has set up SRS, notify RRC that SRS has been released. (D) Clear all configured downlink assignments and configured uplink grants. (E) Clear all PUSCH for semi-persistent CSI reporting. (F) Maintain the N_TA for this TAG.

[0208] A terminal device may decide not to perform any uplink transmissions in a serving cell, except for the transmission of the random access preamble in the SpCell and the transmission of the MSGA (in 2-step RACH), based on the fact that one or more time adjustment timers associated with the PTAG are not running.

[0209] Based on the above description, various embodiments will be explained. Note that the processes described above may be applied to any processes that are omitted in the following description.

[0210] Figure 5 is a block diagram showing the configuration of the terminal device (UE122) in this embodiment. Note that, to avoid complicating the explanation, Figure 5 only shows the main components closely related to this embodiment.

[0211] The UE122 shown in Figure 5 consists of a receiving unit 500 that receives control information (DCI, MAC CE, RRC signaling, etc.) from a base station device, a processing unit 502 that processes according to the parameters included in the received control information, and a transmitting unit 504 that transmits control information (UCI, RRC signaling, etc.) to the base station device. The base station device mentioned above may be an eNB102 or a gNB108. Furthermore, the processing unit 502 may include some or all of the functions of various layers (for example, the physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processing unit 502 may include some or all of the physical layer processing unit, MAC layer processing unit, RLC layer processing unit, PDCP layer processing unit, SDAP layer processing unit, RRC layer processing unit, and NAS layer processing unit. In addition to or instead of the above, the receiver 500 may include some or all of the functions of various layers (e.g., physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the receiver 500 may include some or all of the physical layer receiver, MAC layer receiver, RLC layer receiver, PDCP layer receiver, SDAP layer receiver, RRC layer receiver, and NAS layer receiver.

[0212] Figure 6 is a block diagram showing the configuration of the base station device in this embodiment. To avoid making the explanation complicated, Figure 6 shows only the main components that are closely related to this embodiment. The base station device mentioned above may be eNB102 or gNB108.

[0213] The base station device shown in Figure 6 consists of a transmitting unit 600 that transmits control information (DCI, MAC CE, RRC signaling, etc.) to the UE 122, a processing unit 602 that creates control information (DCI, RRC signaling including parameters, etc.) and transmits it to the UE 122, causing the processing unit 502 of the UE 122 to perform processing, and a receiving unit 604 that receives control information (UCI, RRC signaling, etc.) from the UE 122. Furthermore, the processing unit 602 may include some or all of the functions of various layers (for example, the physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processing unit 602 may include some or all of the physical layer processing unit, MAC layer processing unit, RLC layer processing unit, PDCP layer processing unit, SDAP layer processing unit, RRC layer processing unit, and NAS layer processing unit. In addition to or instead of the above, the transmitter 600 may include some or all of the functions of various layers (e.g., physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the transmitter 600 may include some or all of the physical layer transmitter, MAC layer transmitter, RLC layer transmitter, PDCP layer transmitter, SDAP layer transmitter, RRC layer transmitter, and NAS layer transmitter.

[0214] Conditional LTM cell switching is described below. Conditional LTM cell switching may be performed on candidate target SpCells that meet the execution conditions. UE122 receives RRC signaling from the base station device, which includes one or more conditional LTM candidate information elements, and based on this, UE122 sets candidate target SpCells associated with each conditional LTM candidate information element received from the base station device. The candidate target SpCells may be candidates for LTM target cells in conditional LTM cell switching. The conditional LTM candidate information elements may be managed by identifiers such as LTM candidate identifiers. UE122 may evaluate the state of the set candidate target SpCells. UE122 performs the evaluation and may trigger an LTM cell switching procedure on one or more candidate target SpCells that meet the execution conditions. The UE122 may apply one of the conditional LTM candidate setting information elements included in the conditional LTM candidate information element associated with one or more candidate target SpCells that satisfy the execution condition. The conditional LTM candidate information element and the conditional LTM candidate setting information element may be information elements having the same information as the aforementioned LTM candidate information element and LTM candidate setting information element, or they may be the same information element in addition to or instead of the aforementioned LTM candidate information element and LTM candidate setting information element. The conditional LTM candidate information element may be replaced with an LTM candidate information element, and the conditional LTM candidate setting information element may be replaced with an LTM candidate setting information element. The execution condition may be associated with the candidate target SpCell, or it may be associated with the conditional LTM candidate information element.

[0215] The UE122 may evaluate whether the execution conditions are met in the evaluation. One or more execution conditions may be associated with one or more conditional LTM candidate information elements. The execution conditions may be set in the UE122 by RRC signaling, or by information elements included in RRC signaling that include one or more conditional LTM candidate information elements. The execution conditions may be, for example, one or more of the following conditions. (C-1) The measurement parameters of the beam associated with the candidate target SpCell are greater than the offset value of the measurement parameters of the beams constituting the current serving cell (SpCell). (C-2) The measurement parameters of the beam associated with the candidate target SpCell are greater than the threshold. (C-3) The measurement parameters of the beams constituting the current serving cell (SpCell) are less than the first threshold, and the measurement parameters of the beam associated with the candidate target SpCell are greater than the second threshold. (C-4) The measurement parameters of the candidate target SpCell are greater than the offset value of the measurement parameters of the current serving cell (SpCell). (C-5) The measurement parameters of the candidate target SpCell are greater than the threshold. (C-6) The measurement parameters of the current serving cell (SpCell) are less than the first threshold, and the measurement parameters of the candidate target SpCell are greater than the second threshold.

[0216] In addition to the above conditions, other conditions may also be considered. For example, the execution condition may be that the condition (Cn)[n=1,2,...,6] is satisfied for a certain period of time. The setting of the period may be included in the RRC signaling as an execution condition. The period may be set in the UE122 via an information element named TimeToTrigger, or via an information element with another name. In addition to or instead of the above, for example, the beam measurement item of (Cn)[n=1,2,3] may be a measurement item for one beam or a measurement item for multiple beams.

[0217] The measurement items may be, for example, Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), Signal-to-Interference-and-Noise Ratio (SINR), or other indicators. The UE122 may measure the beam measurement items using SSB, CSI-RS (Channel State Information-Reference Signal), or a signal with another name. The beam constituting the current serving cell (SpCell) may be referred to as the serving beam or the current beam. The UE122 may measure the measurement items of a single cell using multiple signals of the same type associated with that cell. The single type of signal may be SSB, CSI-RS, or a signal with another name, and the choice of which signal to use may be set in the UE122 by the network (base station equipment).

[0218] An example of the processing of the terminal device (UE122) in this embodiment will be explained using Figure 9. In this embodiment, the processing unit 502 of UE122 may include an RRC processing unit for processing RRC, a PDCP processing unit for processing PDCP, an RLC processing unit for processing RLC, a MAC processing unit for processing MAC, and a PHY processing unit for processing PHY.

[0219] Figure 9 shows an example of the processing of UE122 in this embodiment. The processing unit 502 of UE122 makes a conditional judgment (step S900) and operates based on the judgment (step S902).

[0220] The UE122 may receive a Timing Advance Command (TA) associated with an LTM candidate information element from the base station equipment via MAC CE. The LTM candidate information element may be associated with a candidate target identifier. The MAC CE may include the candidate target identifier and the TA command. The UE122 may store the received TA command. The candidate target identifier may be replaced with other information that can identify the candidate target SpCell to which the TA command applies. The TA command may indicate an index value T_A used by the UE122 to control the amount of Timing Adjustment that needs to be applied when a conditional LTM cell switchover is performed. The index value T_A may be a value used for Timing Advance and may be used to calculate the value of N_TA.

[0221] The UE122 may manage one or more synchronization timers associated one-to-one with each of one or more candidate target SpCells. The UE122 may receive RRC signaling from the base station device, including settings for the synchronization timers. The UE122 may set the initial value of the synchronization timers according to the settings for the synchronization timers. In addition or alternatively, it may set a default value for the initial value of the synchronization timers. In addition or alternatively, it may set the initial value of the synchronization timers according to MAC CE received from the base station device. The settings for the synchronization timers may be associated with one or more (conditional) LTM candidate information elements. The initial values ​​of the synchronization timers may be different or common depending on the one or more (conditional) LTM candidate information elements to which they are associated. Furthermore, the one or more synchronization timers may each be associated with one or more (conditional) LTM candidate information elements.

[0222] Based on receiving a MAC CE containing the TA command, the UE122 may start or restart the synchronization timer associated with the candidate target SpCell associated with the TA command. While the synchronization timer is running, the UE122 may determine that it is UL synchronized with the candidate target SpCell. If a conditional LTM cell switching procedure is triggered, the UE122 may determine that a RACH-less LTM cell switching is ongoing, at least based on the fact that the synchronization timer is running. Based on the expiration of the synchronization timer, the UE122 may determine that it is not UL synchronized with the candidate target SpCell. In addition to or instead of the above, based on the expiration of the synchronization timer, the UE122 may determine that the TAC (or index value T_A) associated with the candidate target SpCell associated with the synchronization timer is invalid, or it may release the TAC. If a conditional LTM cell switching procedure is triggered, the UE122 may initiate a random access procedure to the LTM target cell, at least based on the fact that the synchronization timer is not running. The LTM target cell may be a cell that is the target of LTM cell switching in the conditional LTM cell switching procedure. The LTM target cell may be a candidate target SpCell that satisfies the execution conditions. If multiple candidate target SpCells satisfy the execution conditions, the LTM target cell may be one of the selected candidate target SpCells. The LTM target cell may be referred to as a selected cell. A candidate target SpCell that satisfies the execution conditions may also be referred to as a triggered cell.

[0223] Furthermore, based on the triggering of the conditional LTM cell switching procedure, the UE122 may stop one or more operating synchronous timers, excluding the synchronous timer associated with the LTM target cell. In addition to or instead of this, the UE may stop the synchronous timer associated with the LTM target cell based on the triggering of the conditional LTM cell switching procedure.

[0224] In the conditional LTM cell switching procedure, the UE122 may apply the index value T_A indicated by the TA command to the PTAG of the LTM target cell. In addition, it may set the value of the synchronization timer associated with the LTM target cell to the TA timer (Timer Alignment Timer) associated with the PTAG and start the TA timer. Alternatively, it may set the value of the TA timer associated with the PTAG based on the setting of the TAG included in the LTM candidate setting associated with the LTM target cell and start the TA timer. Alternatively, it may compare the value of the synchronization timer associated with the LTM target cell with the value of the TA timer of the PTAG included in the setting of the TAG included in the LTM candidate setting associated with the LTM target cell, set the smaller value to the TA timer associated with the PTAG and start the TA timer. Alternatively, it may compare the value of the synchronization timer associated with the LTM target cell with the value of the TA timer of the PTAG included in the setting of the TAG included in the LTM candidate setting associated with the LTM target cell, set the larger value to the TA timer associated with the PTAG and start the TA timer.

[0225] The UE122 may perform a MAC reset during the LTM cell switching procedure. The MAC layer processing unit of the UE122 may perform the MAC reset in accordance with a request from a higher layer (RRC layer processing unit). During the MAC reset, the UE122 may stop one or more operating timers, excluding one or more synchronization timers associated with one or more of the LTM target cells.

[0226] The UE122 may, based on having performed an LTM cell switchover without RACH in the LTM cell switchover procedure, include information indicating the value of the synchronization timer associated with the LTM target cell in the RRC reset completion message and transmit it to the base station equipment providing the LTM target cell. In addition to or instead of this, the UE122 may include information indicating the value of the synchronization timer associated with one or more candidate target SpCells in the RRC reset completion message and transmit it to the base station equipment providing the LTM target cell. The UE122 may transmit the RRC reset completion message via SRB1 or SRB3.

[0227] The base station device may be a base station device that provides the source cell when the UE122 performs the conditional LTM cell switching. The base station device that provides the source cell may be called a source gNB. The base station device that provides the target cell may be called a target gNB. If the CU that provides the source cell and the CU that provides the target cell are the same, then the source gNB and the target gNB may both be the base station device. The source gNB may provide the target gNB with information about one or more synchronization timers held by the UE122. The information about one or more synchronization timers may be, for example, information indicating the remaining time of an operating synchronization timer, or in addition to or instead of that, information identifying a candidate target SpCell associated with the operating synchronization timer, or in addition to or instead of that, information identifying the UE122.

[0228] The UE122 may, based on the fact that a UE-based TA (Timing Advance) measurement has been set for the LTM target cell and the TA (Timing Advance) of the LTM target cell has been successfully measured, set the value of the TA timer associated with the PTAG based on the setting of the TAG included in the LTM candidate setting associated with the LTM target cell, and start the TA timer. In addition or alternatively, the UE122 may, based on the fact that a synchronization timer for the LTM target cell is operating, apply the index value T_A indicated by the TA command associated with the synchronization timer to the PTAG of the LTM target cell. In addition or alternatively, the UE122 may, based on the fact that a UE-based TA (Timing Advance) measurement has not been set for the LTM target cell or the TA (Timing Advance) of the LTM target cell has not been successfully measured, set the value of the synchronization timer associated with the LTM target cell to the value of the TA timer associated with the PTAG, and start the TA timer.

[0229] The embodiments described above may be combined with each other. Furthermore, although the examples of the embodiments described above describe the operation in a conditional LTM cell switching procedure, the embodiments are not limited to this, and may also describe the operation in a normal LTM cell switching procedure, i.e., a procedure that performs cell switching based on the receipt of an LTM cell switching command (MAC CE) from the base station device. In other words, the conditional LTM cell switching procedure and the LTM cell switching procedure may be interchangeable. Also, in the embodiments described above, applying the LTM candidate cell setting may mean executing the RRC reset procedure using a message regarding the reset of the RRC connection included in the LTM candidate cell setting. Also, in the embodiments described above, the SpCell among one or more LTM candidate cells associated with the setting of the selected LTM candidate cell may be a single SpCell set by the terminal device using the cell group setting included in the LTM candidate cell setting. Also, in the embodiments described above, "execute," "start," and "trigger" may be interchangeable. In addition to or instead of the above, the RRC reset procedure in the embodiments described above may be performed independently in each cell group in the case of NR-DC. For example, if the LTM candidate cell settings associated with an LTM target cell are included in the LTM candidate target settings associated with the MCG (e.g., the LTM-Config information element described above), the RRC processing unit of UE122 will execute the RRC reset procedure in the MCG, but will not need to execute the RRC reset procedure in the SCG. Also, in each of the embodiments described above, "when it is determined that all conditions A, B, C, ... are met" may be rephrased as "when all conditions A, B, C, ... are met," etc. Also, in each of the embodiments described above, "when it is determined that any of conditions A, B, C, ... are not met" may be rephrased as "when any of conditions A, B, C, ... are not met" or "when it is not determined that all conditions A, B, C, ... are met," etc.

[0230] Furthermore, unless otherwise specified, the term "wireless bearer" in the above description may refer to a DRB, an SRB, or both a DRB and an SRB.

[0231] Furthermore, in the above explanation, terms such as "user plane," "user plane protocol," and "user plane interface" may be used interchangeably.

[0232] Furthermore, in the above description, "receiving a DCI or MAC control element that instructs a change in the serving cell to one or more target cells" may be rephrased as "being instructed to change the serving cell to one or more target cells."

[0233] Furthermore, in the above explanation, expressions such as "terminal device variable," "terminal variable," and "variable" may be interchangeable.

[0234] Furthermore, unless otherwise specified, the serving cell change described above may refer to a change in a Layer 1 or Layer 2 serving cell.

[0235] Furthermore, in the above explanation, expressions such as "provided," "signaled," and "selected" may be interchangeable.

[0236] Furthermore, in the above explanation, expressions such as "LTM candidate target identifier" and "LTM candidate target entry identifier" may be interchangeable.

[0237] Furthermore, in the above explanation, expressions such as "to be notified" and "to be pointed out" may be used interchangeably.

[0238] Furthermore, in the above explanation, expressions such as "link," "correspond," and "associate" may be used interchangeably.

[0239] Furthermore, in the above explanation, expressions such as "included," "included," and "was included" may be interchangeable.

[0240] Furthermore, in the above explanation, "the aforementioned..." may be replaced with "the aforementioned...".

[0241] Furthermore, in the above explanation, expressions such as "it has been confirmed that...", "it is set that...", and "it includes..." can be used interchangeably.

[0242] Furthermore, in the examples of processes or process flows described above, some or all of the steps may not be executed. Also, in the examples of processes or process flows described above, the order of the steps may differ. Also, in the examples of processes or process flows described above, some or all of the processes within each step may not be executed. Also, in the examples of processes or process flows described above, the order of the processes within each step may differ. Furthermore, in the above description, "perform B based on the fact that A is true" may be rephrased as "perform B." That is, "performing B" may be performed independently of "being true A."

[0243] Furthermore, in the above explanation, "A may be replaced with B" may include not only replacing A with B, but also replacing B with A. Also, in the above explanation, if it states "C may be D" and "C may be E", it may also include "D may be E". Also, in the above explanation, if it states "F may be G" and "G may be H", it may also include "F may be H".

[0244] Furthermore, in the above explanation, if condition "A" and condition "B" are contradictory conditions, condition "B" may be expressed as an "other" condition of condition "A".

[0245] The program running in the device according to this embodiment may be a program that controls the Central Processing Unit (CPU), etc., to make the computer function in order to realize the functions of this embodiment. The program or the information handled by the program is temporarily loaded into volatile memory such as Random Access Memory (RAM) during processing, or stored in non-volatile memory such as flash memory or a Hard Disk Drive (HDD), and read, modified, and written by the CPU as needed.

[0246] Furthermore, some parts of the apparatus in the above-described embodiment may be implemented using a computer. In that case, the program for implementing this control function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" here refers to a computer system built into the apparatus, and includes hardware such as an operating system and peripheral devices. The "computer-readable recording medium" may be any of the following: a semiconductor recording medium, an optical recording medium, a magnetic recording medium, etc.

[0247] Furthermore, "computer-readable recording media" may include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, as well as those that hold programs for a certain period of time, such as volatile memory inside computer systems that act as servers or clients in such cases. In addition, the above-mentioned programs may be for the purpose of realizing some of the functions described above, and may also be programs that can realize the above-mentioned functions in combination with programs already recorded in the computer system.

[0248] Furthermore, each functional block or feature of the apparatus used in the embodiments described above may be implemented or executed by an electrical circuit, typically an integrated circuit or a combination of integrated circuits. Electrical circuits designed to perform the functions described herein may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or combinations 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 consist of digital or analog circuits. Also, if advances in semiconductor technology lead to the emergence of integrated circuit technologies that replace current integrated circuits, it may be possible to use integrated circuits based on such technologies.

[0249] It should be noted that this embodiment is not limited to the embodiments described above. Although the embodiments describe an example of a device, this embodiment is not limited to this and can be applied to stationary or non-movable electronic devices installed indoors or outdoors, such as terminal devices or communication devices for AV equipment, kitchen equipment, cleaning and washing machines, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0250] Although this embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of this embodiment are also included. Furthermore, this embodiment can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this embodiment. In addition, configurations in which elements described in the above embodiment that produce similar effects are substituted for each other are also included.

[0251] One aspect of the present invention can be used, for example, in communication systems, communication equipment (e.g., mobile phone devices, base station devices, wireless LAN devices, or sensor devices), integrated circuits (e.g., communication chips), or programs.

[0252] 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 Processing Unit 504, 600 Transmitter

Claims

1. A terminal device that communicates with a base station device, comprising: a receiving unit that receives RRC (Radio Resource Control) signaling from the base station device; and a processing unit, wherein the RRC signaling includes one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements; the receiving unit receives MAC (Medium Access Control) signaling from the base station device, which includes information identifying one LTM candidate information element and information identifying the value of TA (Timing Advance) associated with the one LTM candidate information element; the processing unit starts a synchronization timer associated with the one LTM candidate information element based on the receipt of the MAC signaling; and, based on the determination that the conditions associated with the one LTM candidate information element have been met, (a) applies the value of the TA associated with the one LTM candidate information element as the value of TA in the PTAG; (b) applies the value of the synchronization timer associated with the one LTM candidate information element as the value of the TA timer; and (c) starts the TA timer.

2. A base station device that communicates with a terminal device, comprising: a transmitting unit that transmits RRC (Radio Resource Control) signaling to the terminal device; and a processing unit, wherein the processing unit includes in the RRC signaling one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements; and by applying the RRC signaling to the terminal device, the terminal device receives MAC (Medium Access) information including information identifying one LTM candidate information element and information identifying the TA (Timing Advance) value associated with the one LTM candidate information element. A base station device that receives a Control signaling from the base station device, starts a synchronization timer associated with one LTM candidate information element based on the reception of the MAC signaling, and, based on the determination that one of the conditions associated with one LTM candidate information element has been met, (a) applies the value of the TA associated with one LTM candidate information element as the value of the TA of the PTAG, (b) applies the value of the timer associated with one LTM candidate information element as the value of the TA timer, and (c) starts the TA timer.

3. A method for a terminal device to communicate with a base station device, comprising the steps of: receiving an RRC (Radio Resource Control) signaling from the base station device; receiving a MAC (Medium Access Control) signaling from the base station device, wherein the RRC signaling includes one or more LTM (L1 / L2 Triggered Mobility) candidate information elements and settings relating to conditions associated with each of the one or more LTM candidate information elements, and including information identifying one LTM candidate information element and information identifying the value of TA (Timing Advance) associated with one LTM candidate information element; and the processing unit starting a synchronization timer associated with one LTM candidate information element based on the receipt of the MAC signaling; and determining that the conditions associated with one LTM candidate information element have been met, (a) applying the value of the TA associated with one LTM candidate information element as the value of TA in the PTAG; (b) applying the value of the synchronization timer associated with one LTM candidate information element as the value of the TA timer; and (c) starting the TA timer.

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