Terminal and communication method

Abstract

This terminal comprises: a reception unit that receives, from a radio access network (RAN) node of a first radio access technology (RAT), a radio resource control (RRC) message including information pertaining to an execution condition for inter-RAT lower layer triggered mobility (LTM); and a control unit that monitors whether the execution condition is satisfied within a period based on a parameter indicating a period until the execution condition is satisfied. When the execution condition is satisfied within the period based on the parameter indicating the period until the execution condition is satisfied, the control unit executes an LTM handover to an RAN node of a second RAT.

Description

Terminal and Communication Method

[0001] The present invention relates to a terminal and a communication method in a communication system.

[0002] In 3GPP (registered trademark) (3rd Generation Partnership Project), studies on a radio communication scheme called 5G or NR (New Radio) (hereinafter, this radio communication scheme is referred to as "5G" or "NR") are progressing, in order to achieve further increase in system capacity, further increase in data transmission speed, further reduction of latency in a radio section, and the like. In 5G, various radio technologies are being studied to satisfy the requirement that the latency of the radio section is 1 ms or less while achieving a throughput of 10 Gbps or more.

[0003] In NR, a network architecture including 5GC (5G Core Network) corresponding to EPC (Evolved Packet Core) which is a core network in the network architecture of LTE (Long Term Evolution) and NG-RAN (Next Generation - Radio Access Network) corresponding to E-UTRAN (Evolved Universal Terrestrial Radio Access Network) which is RAN (Radio Access Network) in the network architecture of LTE is being studied (for example, Non-Patent Document 1).

[0004] Furthermore, various requirements are being studied for next-generation 6G. For example, the requirements include ultra broadband communication, mission critical communication, ultra massive connection, universal coverage, intelligent connection, ubiquitous sensing, and the like.

[0005] To meet these requirements, the new concept aims for extensibility (e.g., making it more effective for future use), ease of operation, customizability (e.g., making it easier to operate), and sustainability (e.g., cost reduction, a more robust configuration, and resilience). Furthermore, guaranteed communication, ensuring a minimum level of performance at all times, is being considered.

[0006] Furthermore, to enhance mobility, functional enhancements are expected to be made to support cases where inter-Central Unit (CU) LTM (Lower Layer Triggered Mobility) and DC (Dual Connectivity) are performed while maintaining LTM (for example, Non-Patent Document 2).

[0007] 3GPP TS 23.501 V18.7.0 (2024-09)3GPP TSG-RAN Meeting #101 RP-232618, Bengaluru, India, 11-15 September 2023

[0008] Initially, when 6G is deployed, it is expected that 6G cell coverage will be localized. Therefore, frequent switching from 6G cells to 5G cells or from 5G cells to 6G cells is anticipated. To improve the user experience, inter-RAT-LTM handover with minimal downtime is required.

[0009] This invention has been made in view of the above points, and aims to implement InterRAT (Radio Access Technology) LTM (Lower layer Triggered Mobility).

[0010] According to the disclosed technology, a terminal is provided which includes a receiving unit that receives an RRC (Radio Resource Control) message containing information relating to the execution conditions of an inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) from a RAN (Radio Access Network) node of a first RAT, and a control unit that monitors whether the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, and if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, the control unit performs an LTM handover to the RAN node of a second RAT.

[0011] According to the disclosed technology, it is possible to perform InterRAT (Radio Access Technology) LTM (Lower layer Triggered Mobility).

[0012] This is a diagram illustrating an example of a communication system. This is a diagram illustrating an example of a communication system in a roaming environment. This is a sequence diagram illustrating an example of mobility (1) in an embodiment of the present invention. This is a sequence diagram illustrating an example of mobility (2) in an embodiment of the present invention. This is a sequence diagram illustrating an example of mobility (3) in an embodiment of the present invention. This is a sequence diagram illustrating an example of mobility (4) in an embodiment of the present invention. This is a sequence diagram illustrating an example of mobility (5) in an embodiment of the present invention. This is a sequence diagram illustrating an example of mobility (6) in an embodiment of the present invention. This is a diagram illustrating an example of the functional configuration of the base station 10 and network node 30 in an embodiment of the present invention. This is a diagram illustrating an example of the functional configuration of the terminal 20 in an embodiment of the present invention. This is a diagram illustrating an example of the hardware configuration of the base station 10 and terminal 20 in an embodiment of the present invention.

[0013] Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to those described below.

[0014] In the operation of the wireless communication system according to the embodiments of the present invention, existing technologies may be used as appropriate. However, such existing technologies include, for example, existing LTE, but are not limited to existing LTE. Furthermore, the term "LTE" as used herein has a broad meaning that includes LTE-Advanced, LTE-Advanced and later technologies (e.g., NR), or wireless LAN (Local Area Network), unless otherwise specified.

[0015] Furthermore, in the embodiments of the present invention, "configuring" wireless parameters means that predetermined values ​​are pre-configured, or that wireless parameters notified from the network node 30 or terminal 20 are configured.

[0016] Figure 1 is a diagram illustrating an example of a communication system. As shown in Figure 1, the communication system consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assumed to correspond to each function, but one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0017] The RAN (Radio Access Network) is a network node 30 having wireless access functionality, which may include a base station 10, and is connected to a UE, AMF (Access and Mobility Management Function), and UPF (User plane function). The AMF is a network node 30 having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 interconnected with the DN (Data Network) and having functions such as a PDU (Protocol Data Unit) session point to the outside, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network in the embodiment of the present invention, multiple network slices are constructed.

[0018] AMF is connected to UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0019] The SMF is a network node 30 that has functions such as session management, IP (Internet Protocol) address allocation and management for UEs, DHCP (Dynamic Host Configuration Protocol) functionality, ARP (Address Resolution Protocol) proxy, and roaming functionality. The NEF is a network node 30 that has the function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 that has functions such as selecting the network slice to which the UE connects, determining the allowed NSSAI (Network Slice Selection Assistance Information), determining the NSSAI to be set, and determining the AMF set to which the UE connects. The PCF is a network node 30 that has the function of controlling network policies. The AF is a network node 30 that has the function of controlling application servers. The NRF is a network node 30 that has the function of discovering NF instances that provide services. The UDM is a network node 30 that manages subscriber data and authentication data. The UDM is connected to the UDR (User Data Repository) that holds the said data.

[0020] Figure 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Figure 2, the network consists of a terminal 20 (UE) and multiple network nodes 30. Hereafter, one network node 30 will be assigned to each function, but one network node 30 may implement multiple functions, or multiple network nodes 30 may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0021] The RAN is a network node 30 having wireless access functionality and is connected to the UE, AMF, and UPF. The AMF is a network node 30 having functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 interconnected with the DN, having functions such as external PDU session point, packet routing and forwarding, and user plane QoS handling. The UPF and DN constitute a network slice. In the wireless communication network according to the embodiment of the present invention, multiple network slices are constructed.

[0022] AMF is connected to UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0023] SMF is a network node 30 that has functions such as session management, IP address allocation and management for UEs, DHCP functionality, ARP proxy, and roaming functionality. NEF is a network node 30 that has the function of notifying other NFs of capabilities and events. NSSF is a network node 30 that has functions such as selecting the network slice to which the UE connects, determining which NSSAIs are allowed, determining which NSSAIs are configured, and determining which AMF set the UE connects to. PCF is a network node 30 that has the function of controlling network policies. AF is a network node 30 that has the function of controlling application servers. NRF is a network node 30 that has the function of discovering NF instances that provide services. SEPP is an opaque proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). In Figure 2, vSEPP is the SEPP in the visited network, and hSEPP is the SEPP in the home network.

[0024] As shown in Figure 2, the UE is in a roaming environment connected to the RAN and AMF in the Visited PLMN. The Visited PLMN and Home PLMN are connected via vSEPP and hSEPP. The UE can communicate with the UDM of the Home PLMN, for example, via the AMF of the Visited PLMN.

[0025] Furthermore, in an NG-RAN (Next Generation Radio Access Network), a gNB, which is a RAN node, may have an architecture separated into gNB-CU (Central Unit) and gNB-DU (Distributed Unit). One gNB-CU may accommodate multiple gNB-DUs, and one gNB-DU may accommodate multiple cells.

[0026] Initially, when 6G is deployed, it is expected that 6G cell coverage will be localized. Therefore, frequent switching from 6G cells to 5G cells or from 5G cells to 6G cells is anticipated. To improve the user experience, inter-RAT-LTM handover with minimal downtime is required.

[0027] 6G is expected to use the FR3 or FR2 frequency band. Mobility robustness is improved when the UE triggers the execution of mobility at high frequencies. However, the details of how to implement Conditional Inter-RAT LTM or Conditional inter-RAT HO for the UE to trigger mobility were not specified.

[0028] When a UE connects to a 6GRAN node and receives an InterRAT mobility configuration (e.g., RRCReconfiguration for conditional InterRAT-LTM or conditional InterRAT handover), it may obtain the execution condition for conditional InterRAT-LTM or conditional InterRAT handover to a 5GRAN node. For example, if the execution conditions shown in 1)-4) below are satisfied within the time period (TimeToTrigger) that indicates the time until the trigger condition is met, the UE may autonomously trigger InterRAT-LTM or InterRAT handover.

[0029] Alternatively, when the UE connects to a 5GRAN node and receives an InterRAT mobility configuration (e.g., an RRCReconfiguration for a conditional InterRAT-LTM or conditional InterRAT handover), it may obtain the execution condition for a conditional InterRAT-LTM or conditional InterRAT handover to a 6GRAN node. For example, if the execution conditions shown in 1)-4) below are satisfied within the time period (TimeToTrigger) that indicates the time until the trigger condition is met, the UE may autonomously trigger an InterRAT-LTM or InterRAT handover.

[0030] 1) Execution condition (inter-RAT LTM1): The beam quality of the inter-RAT neighbor cell becomes better than the threshold (the L1 / L3 measurement quality (RSRP / RSRQ / SINR) of the beam (SSB / CSI-RS) becomes better than the threshold).

[0031] 2) Execution condition (inter-RAT LTM2): The quality of the serving cell's beam deteriorates below threshold 1, and the quality of the inter-RAT neighbor cell's beam improves above threshold 2.

[0032] 3) Execution condition (event B1): The quality of the inter-RAT neighbor cell (L3 measurement quality of the cell (RSRP / RSRQ / SINR)) becomes better than the threshold.

[0033] 4) Execution condition (event B2): The quality of the primary cell deteriorates below threshold 1, and the quality of the inter-RAT neighbor cell improves above threshold 2.

[0034] Figure 3 is a sequence diagram illustrating an example of mobility (1) in an embodiment of the present invention. In step S101, the UE performs RRC Reconfiguration of Inter-RAT Mobility (e.g., RRC Reconfiguration of Conditional Inter-RAT LTM or conditional inter-RAT HO including execution conditions) The condition is received from the 6GRAN node. Note that RRCReconfiguration is just one example and may be replaced with other RRC messages such as system information. In step S102, the UE monitors the execution conditions for interRAT-LTM or interRAT handover. In step S103, the execution conditions for interRAT-LTM or interRAT handover are satisfied. Note that step S103 may be satisfied within a parameter (TimeToTrigger) that indicates the period until the trigger condition is met. In step S104, the UE and the 5GRAN node execute the random access procedure.

[0035] Figure 4 is a sequence diagram illustrating an example (2) of mobility in an embodiment of the present invention. In step S201, the UE receives the configuration of Inter-RAT Mobility (RRC Reconfiguration of Conditional Inter-RAT LTM or Conditional Inter-RAT Handover including execution conditions) from the 5GRAN node. In step S202, the UE monitors the execution conditions of Inter-RAT LTM or Inter-RAT Handover. In step S203, the execution conditions of Inter-RAT LTM or Inter-RAT Handover are satisfied. Step S203 may be satisfied within a parameter (TimeToTrigger) indicating the period until the trigger condition is met. In step S204, the UE and the 6GRAN node execute a random access procedure.

[0036] Figure 5 is a sequence diagram illustrating an example of mobility (3) in an embodiment of the present invention. Figure 5 shows an NG-based inter-RAT-LTM procedure. In step S301, the UE sends an inter-RAT measurement report (L1 / L3 inter-RAT measurement reporting (6G L1 / L3 cell / beam measurement results)) including 6GL1 / L3 cell and / or beam measurement results to the source 5GNB. In step S302, the source 5GNB sends a handover request (HO required (Source NG-RAN Node to Target NG-RAN Node Transparent Container (LTM info setup)))) including LTM setup information from the source NG-RAN node to the target NG-RAN node to the 5GC.

[0037] In step S303, 5GC sends a handover request (Inter 5GC and 6GC signaling (containing Source NG-RAN Node to Target NG-RAN Node Transparent Container (LTM info setup))) containing LTM setup information from the source NG-RAN node to the target NG-RAN node to 6GC via signaling between 5GC and 6GC. In step S304, 6GC sends a handover request (HO request (Source NG-RAN Node to Target NG-RAN Node Transparent Container (LTM info setup))) containing LTM setup information from the source NG-RAN node to the target NG-RAN node to the target 6GNB.

[0038] In step S305, the target 6GNB sends a handover request acknowledgment (HO request Ack (Target NG-RAN Node to Source NG-RAN Node Transparent Container)) from the target NG-RAN node to the source NG-RAN node to the 6GC. In step S306, the 6GC sends a handover request acknowledgment (HO request Ack (Target NG-RAN Node to Source NG-RAN Node Transparent Container)) from the target RAN node to the source NG-RAN node to the 5GC via signaling between the 5GC and the 6GC.

[0039] In step S307, the 5GC sends a handover command (HO command (Target NG-RAN Node to Source NG-RAN Node Transparent Container(SSB info, cell config info, complete candidate config indicator, LTM CFRA resource config, LTM CFRA resource config for SUL)) from the target NG-RAN node to the source NG-RAN node, which includes SSB information, cell configuration information, a complete candidate config indicator, LTM CFRA resource configuration, and LTM CFRA resource configuration for SUL) to the source 5GNB.

[0040] In step S308, source 5GNB sends RRCReconfiguration (including Inter-RAT LTM execution condition) to UE. In step S309, UE sends RRCReconfigurationComplete to source 5GNB.

[0041] In step S310, source 5GNB sends a Random Access Channel (RACH) order via PDCCH (Physical Downlink Control Channel) including the 6G cell ID to UE. In step S311, UE sends a RACH preamble to target 6GNB.

[0042] In step S312, the target 6GNB transmits a TA info transfer (6G cell ID, TA value, preamble index, RA-RNTI, source gNB DU ID, Tag ID pointer) including the 6G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU-ID, and Tag ID pointer to the 6GC. In step S313, the 6GC transmits a TA info transfer (6G cell ID, TA value, preamble index, RA-RNTI, source gNB DU ID, Tag ID pointer) including the 6G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU-ID, and Tag ID pointer to the 5GC via signaling between the 5GC and the 6GC.

[0043] In step S314, the 5GC transmits a TA info transfer (6G cell ID, TA value, preamble index, RA-RNTI, source gNB DU ID, Tag ID pointer) including the 6G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU-ID, and Tag ID pointer to the source 5GNB.

[0044] In step S315, the UE detects that the inter-RAT-LTM execution condition is satisfied. In step S316, the UE transmits a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) including the 6G cell ID, TCI state ID, TA value, and Tag ID pointer to the source 5GNB.

[0045] In step S317, source 5GNB sends a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) to 5GC, which includes the 6G cell ID, TCI state ID, TA value, and Tag ID pointer.

[0046] In step S318, 5GC sends a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) to 6GC via signaling between 5GC and 6GC.

[0047] In step S319, 6GC sends a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) to target 6GNB, which includes the 6G cell ID, TCI state ID, TA value, and Tag ID pointer. In step S320, UE sends an RRC reconfiguration complete message to target 6GNB.

[0048] Figure 6 is a sequence diagram for explaining a mobility example (4) in an embodiment of the present invention. Note that FIG. 6 illustrates an NG-based inter-RAT-LTM procedure. In step S401, the UE transmits an inter-RAT measurement report (L1 / L3 inter-RAT measurement reporting(5G L1 / L3 cell / beam measurement results)) including 5G L1 / L3 cell and / or beam measurement reports to the source 6GNB. In step S402, the source 6GNB transmits a handover request (HO required(Source NG-RAN Node to Target NG-RAN Node Transparent Container(LTM info setup))) including LTM setup information from the source NG-RAN node to the target NG-RAN node to 6GC.

[0049] In step S403, the 6GC transmits a handover request (Inter 5GC and 6GC signaling (containing Source NG-RAN Node to Target NG-RAN Node Transparent Container(LTM info setup )) including LTM setup information from the source NG-RAN node to the target NG-RAN node to the 5GC via signaling between the 5GC and the 6GC. In step S404, the 5GC transmits a handover request (HO request (Source NG-RAN Node to Target NG-RAN Node Transparent Container(LTM info setup))) including LTM setup information from the source NG-RAN node to the target NG-RAN node to the target 5GNB.

[0050] In step S405, the target 5GNB sends a handover request acknowledgment (HO request Ack (Target NG-RAN Node to Source NG-RAN Node Transparent Container)) from the target NG-RAN node to the source NG-RAN node to the 5GC. In step S406, the 5GC sends a handover request acknowledgment (HO request Ack (Target NG-RAN Node to Source NG-RAN Node Transparent Container)) from the target RAN node to the source NG-RAN node to the 6GC via signaling between the 5GC and the 6GC.

[0051] In step S407, 6GC sends a handover command (HO command (Target NG-RAN Node to Source NG-RAN Node Transparent Container(SSB info, cell config info, complete candidate config indicator, LTM CFRA resource config, LTM CFRA resource config for SUL))) from the target NG-RAN node to the source NG-RAN node, which includes SSB information, cell configuration information, a complete candidate config indicator, LTM CFRA resource configuration, and LTM CFRA resource configuration for SUL.

[0052] In step S408, source 6GNB sends RRCReconfiguration (including Inter-RAT LTM execution condition) to UE. In step S409, UE sends RRCReconfigurationComplete to source 6GNB.

[0053] In step S410, source 6GNB sends a PDCCH ordered RACH (including 5G cell ID) to UE. In step S411, UE sends a RACH preamble to target 5GNB.

[0054] In step S412, target 5GNB transmits TA info transfer (5G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, Tag ID pointer) to 5GC. In step S413, 5GC transmits TA info transfer (5G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, Tag ID pointer) to 6GC via signaling between 5GC and 6GC.

[0055] In step S414, 6GC sends TA info transfer (5G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU-ID, Tag ID pointer) to source 6GNB.

[0056] In step S415, the UE detects that the inter-RAT-LTM execution conditions are met. In step S416, the UE sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) to the source 6GNB, which includes the 5G cell ID, TCI state ID, TA value, and Tag ID pointer.

[0057] In step S417, source 6GNB sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) to 6GC, which includes the 5G cell ID, TCI state ID, TA value, and Tag ID pointer.

[0058] In step S418, 6GC sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) to 5GC via signaling between 5GC and 6GC.

[0059] In step S419, the 5GC sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) to the target 5GNB, which includes the 5G cell ID, TCI state ID, TA value, and Tag ID pointer. In step S420, the UE sends an RRC reconfiguration complete message to the target 5GNB.

[0060] Figure 7 is a sequence diagram illustrating an example (5) of mobility in an embodiment of the present invention. Figure 7 shows an Xn-based inter-RAT-LTM procedure. In step S501, the UE sends an inter-RAT measurement report (L1 / L3 inter-RAT measurement reporting (6G L1 / L3 cell / beam measurement results)) including 6GL1 / L3 cell and / or beam measurement results to the source 5GNB. In step S502, the source 5GNB sends a handover request (LTM info setup) including LTM setup information to the 6GC.

[0061] In step S503, candidate 6GNB sends a Handover request Ack(LTM config(SSB info, cell config info, complete candidate config indicator, LTM CFRA resource config, LTM CFRA resource config for SUL)) to source 5GNB, which includes SSB information, cell configuration information, complete candidate config indicator, LTM CFRA resource config, and LTM CFRA resource config for SUL.

[0062] In step S504, source 5GNB sends an LTM configuration update to candidate 6GNB. In step S505, candidate 6GNB sends an LTM configuration update Ack to candidate 6GNB.

[0063] In step S506, source 5GNB sends RRCReconfiguration (including Inter-RAT LTM execution condition) to UE. In step S507, UE sends RRCReconfigurationComplete to source 5GNB.

[0064] In step S508, source 5GNB sends a PDCCH ordered RACH to UE. In step S509, UE sends a RACH preamble to candidate 6GNB.

[0065] In step S510, candidate 6GNB sends TA information transfer (TA info transfer (6G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, Tag ID pointer)) to source 5GNB, which includes the 6G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, and Tag ID pointer.

[0066] In step S511, the UE detects that the inter-RAT-LTM execution conditions are met. In step S512, the UE sends a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) to the source 5GNB, which includes the 6G cell ID, TCI state ID, TA value, and Tag ID pointer.

[0067] In step S513, source 5GNB sends a cell switch notification (6G Cell ID, TCI state ID, TA value, Tag ID pointer) including the 6G cell ID, TCI state ID, TA value, and tag ID pointer to candidate 6GNB.

[0068] In step S514, candidate 6GNB sends a Handover success message to source 5GNB. In step S515, the core network forwards user data from source 5GNB to candidate 6GNB. In step S516, UE sends an RRCReconfigurationComplete message to candidate 6GNB.

[0069] Figure 8 is a sequence diagram illustrating an example (6) of mobility in an embodiment of the present invention. Figure 8 shows an Xn-based inter-RAT-LTM procedure. In step S601, the UE sends an inter-RAT measurement report (L1 / L3 inter-RAT measurement reporting (6G L1 / L3 cell / beam measurement results)) including 6GL1 / L3 cell and / or beam measurement results to the source 6GNB. In step S602, the source 6GNB sends a handover request (LTM info setup) including LTM setup information to the 6GC.

[0070] In step S603, candidate 5GNB sends a Handover request Ack(LTM config(SSB info, cell config info, complete candidate config indicator, LTM CFRA resource config, LTM CFRA resource config for SUL)) to source 6GNB, which includes SSB information, cell configuration information, a complete candidate configuration indicator, LTM CFRA resource configuration, and LTM CFRA resource configuration for SUL.

[0071] In step S604, source 6GNB sends an LTM configuration update to candidate 5GNB. In step S605, candidate 5GNB sends an LTM configuration update Ack to candidate 5GNB.

[0072] In step S606, source 6GNB sends RRCReconfiguration (including Inter-RAT LTM execution condition) to UE. In step S607, UE sends RRCReconfigurationComplete to source 6GNB.

[0073] In step S608, source 6GNB sends a PDCCH ordered RACH to UE. In step S609, UE sends a RACH preamble to candidate 5GNB.

[0074] In step S610, candidate 5GNB sends TA information transfer (TA info transfer (5G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, Tag ID pointer)) to source 6GNB, which includes the 5G cell ID, TA value, preamble index, RA-RNTI, source gNB-DU ID, and Tag ID pointer.

[0075] In step S611, the UE detects that the inter-RAT-LTM execution conditions are met. In step S612, the UE sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) to the source 6GNB, which includes the 5G cell ID, TCI state ID, TA value, and Tag ID pointer.

[0076] In step S613, source 6GNB sends a cell switch notification (5G Cell ID, TCI state ID, TA value, Tag ID pointer) including the 5G cell ID, TCI state ID, TA value, and tag ID pointer to candidate 5GNB.

[0077] In step S614, candidate 5GNB sends a Handover success message to source 6GNB. In step S615, the core network forwards user data to source 6GNB to candidate 5GNB. In step S616, UE sends an RRCReconfigurationComplete message to candidate 5GNB.

[0078] As a result of the above operation, when 6G is introduced, it is possible to perform inter-RAT-LTM or inter-RAT handover between 5G-RAT and 6G-RAT with improved robustness.

[0079] In other words, it can perform InterRAT (Radio Access Technology) LTM (Lower Layer Triggered Mobility).

[0080] (Device Configuration) Next, an example of the functional configuration of the base station 10, network node 30, and terminal 20 that perform the processing and operations described above will be explained. The base station 10, network node 30, and terminal 20 include the functions to perform the embodiments described above. However, the base station 10, network node 30, and terminal 20 may each be equipped with only some of the functions in the embodiments.

[0081] <Base Station 10 and Network Node 30> Figure 9 shows an example of the functional configuration of a base station 10 and a network node 30. As shown in Figure 9, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Figure 9 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. The network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having multiple different functions on the system architecture may be composed of multiple network nodes 30 separated by function.

[0082] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 or other network node 30 and transmitting the signal by wire or wireless. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 or other network node 30 and obtaining information from the received signal, for example, information from a higher layer. A communication unit including the transmitting unit 110 and the receiving unit 120 may be configured.

[0083] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The transmitting unit 110 also transmits setting information, instructions, and notifications related to the low-power wake-up signal to the terminal 20. The transmitting unit 110 also transmits notifications to the terminal regarding the switching of monitoring operations. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 and obtaining information from the received signals, for example, information from a higher layer. The transmitting unit 110 also has the function of transmitting PSS, SSS, PBCH, DL / UL control signals, etc. to the terminal 20. The receiving unit 120 also receives inter-network node messages from other network nodes.

[0084] The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20. The contents of the setting information include, for example, information related to the operation described in the embodiment.

[0085] The control unit 140 performs control related to setting, instructing, and notifying the operations described in the embodiment. The signal transmission function unit of the control unit 140 may be included in the transmission unit 110, and the signal reception function unit of the control unit 140 may be included in the reception unit 120.

[0086] <Terminal 20> Figure 10 is a diagram showing an example of the functional configuration of terminal 20 in an embodiment of the present invention. As shown in Figure 10, terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Figure 10 is merely an example. Any functional classification and name of functional unit is acceptable as long as it can perform the operations according to the embodiment of the present invention. The transmitting unit 210 and the receiving unit 220 may be collectively referred to as the communication unit.

[0087] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The transmitting unit 210 also transmits capability information related to the low-power wake-up signal to the base station 10. The receiving unit 220 wirelessly receives various signals and acquires signals from higher layers from the received physical layer signals. The receiving unit 220 also has the function of receiving PSS, SSS, PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10. The receiving unit 220 also receives setting information, instructions, and notifications related to paging notification information and the low-power wake-up signal from the base station 10. For example, the receiving unit 220 receives the low-power wake-up signal from the base station 10. The setting unit 230 stores various setting information received from the base station 10 by the receiving unit 220. The setting unit 230 also stores pre-set setting information. The content of the setting information is, for example, information related to the operation described in the embodiment.

[0088] As described in the embodiment, the control unit 240 performs control related to setting, instructing, and notifying the operations described in the embodiment. The signal transmission function unit of the control unit 240 may be included in the transmission unit 210, and the signal reception function unit of the control unit 240 may be included in the reception unit 220.

[0089] (Hardware Configuration) The block diagrams (Figures 9 and 10) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by hardware, software, or a combination thereof. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired, wireless, etc.). A functional block may also be realized by combining the above one device or the above multiple devices with software.

[0090] For example, a base station, terminal, network node, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 11 is a diagram showing an example of the hardware configuration of a base station and a terminal according to one embodiment of the present disclosure. The base station 10 and terminal 20 described above may be physically configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc.

[0091] In this disclosure, any two terms selected from the set of terms such as circuit, device, unit, module, chip, and means may be used interchangeably. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figures, or it may be configured to omit some of the devices.

[0092] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations and control communication by the communication device 1004, or to control the reading, writing, or both of the reading and writing of data in the memory 1002 and storage 1003.

[0093] The processor 1001 controls the entire computer, for example, by running the operating system. The processor 1001 may be composed of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the baseband signal processing unit, call processing unit, etc., may be implemented by the processor 1001. Although only one processor 1001 is shown in the diagram, there may be multiple processors.

[0094] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from the storage 1003, the communication device 1004, or both the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 401 of the terminal 20 may be implemented by a control program stored in the memory 1002 and running on the processor 1001, and other functional blocks may be implemented similarly. The above-described various processes have been explained as being executed by one processor 1001, but they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line, or provided to the computer device via the communication device 1004, for example.

[0095] Furthermore, this disclosure also provides a computer program product, which includes a computer program. This computer program product may implement the steps of the method described in the above embodiments when the computer program is executed by a computer (for example, a processor 1001).

[0096] The memory 1002 is a computer-readable recording medium and may be composed of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), or at least a combination of these. The memory 1002 may also be called a register, cache, main memory, etc. The memory 1002 can store executable programs (program code), software modules, etc., for implementing a wireless communication method according to one embodiment of the present disclosure.

[0097] The storage 1003 is a computer-readable recording medium and may consist of, for example, an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., Compact Disc, Digital Multipurpose Disc, Blu-ray® Disc), a smart card, flash memory (e.g., card, stick, key drive), a floppy® disk, a magnetic strip, or a combination of at least two of these. The storage 1003 may also be called an auxiliary storage device. The above-mentioned storage medium may be, for example, a database, server, or other suitable medium including memory 1002, storage 1003, or both memory 1002 and storage 1003.

[0098] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via a wired network, a wireless network, or both wired and wireless networks, and is also referred to as a network device, network controller, network card, or communication module, for example. The communication device 1004 may include a high-frequency switch, duplexer, filter, frequency synthesizer, or a combination of at least two of these. For example, a transmit / receive antenna, amplifier section, transmit / receive section, or transmission path interface may be implemented by the communication device 1004. The transmit / receive section may be implemented in a physically or logically separated manner, consisting of a transmit section and a receive section.

[0099] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, or a combination of at least two of these). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, or a combination of at least two of these). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0100] Furthermore, each device, such as the processor 1001 and memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0101] Furthermore, the base station 10 and terminal 20 may be configured with hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), a GPU (Graphics Processing Unit), an NPU (Neural Processing Unit), or a combination of at least two of these, and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0102] <Configuration relating to this embodiment> (1) A terminal comprising: a receiving unit that receives an RRC (Radio Resource Control) message containing information relating to the execution conditions of an inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) from the RAN (Radio Access Network) node of a first RAT; and a control unit that monitors whether the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, wherein the control unit performs an LTM handover to the RAN node of a second RAT if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied. (2) The terminal according to paragraph 1, wherein the control unit performs a random access procedure with the RAN node of a second RAT if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied. (3) The terminal according to paragraph 1, wherein the control unit transmits a cell switching notification including the cell ID of the second RAT to the RAN node of the first RAT if the execution condition is satisfied within a period based on a parameter indicating the period until the execution condition is satisfied. (4) The terminal according to paragraph 1, wherein the control unit, upon receiving the RRC message, further receives a PDCCH (Physical Downlink Control Channel) order including the cell ID of the second RAT and transmits a RACH (Random Access Channel) preamble to the RAN node of the second RAT. (5) The terminal according to paragraph 1, wherein the control unit transmits the inter-RAT measurement result of the beam of the second RAT to the RAN node of the first RAT.(Clause 6) A communication method in which a terminal performs the following steps: receiving an RRC (Radio Resource Control) message containing information relating to the execution conditions of an inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) from a RAN (Radio Access Network) node of a first RAT; monitoring whether the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied; and, if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, performing an LTM handover to a RAN node of a second RAT.

[0103] Inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) can be implemented by any of the above configurations. Furthermore, according to paragraphs 2 through 5, when 6G is introduced, an improved robustness-enhanced 5G-RAT and 6G-RAT inter-RAT LTM or inter-RAT handover can be implemented.

[0104] (Supplement to Embodiments) Embodiments of the present invention have been described above, but the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium.

[0105] Each aspect / embodiment described in this disclosure is an LTE (Long Term Evolution), LTE-A (LTE-Advanced), IMT-Advanced (International Mobile Telecommunications-Advanced), 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 5G-A (5G-Advanced), 6G (6th generation mobile communication system), xG (xth generation mobile communication system (where x is, for example, an integer or decimal)), FRA (Future Radio Access), NR (new Radio), NX (New radio access), FX (Future generation radio access), O-RAN (Open Radio Access Network), W-CDMA (Wideband Code Division Multiple Access) (registered trademark), GSM (Global System for Mobile communications) (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE (Institute of Electrical and Electronics Technology) Engineers) 802.11, IEEE 802.11x (where x is any string such as b, a, g, n, ac, ax, be, bn, etc., and x=n is also called Wi-Fi 4, x=ac is Wi-Fi 5, x=ax is Wi-Fi 6 or Wi-Fi 6E, x=be is Wi-Fi 7, x=bn is Wi-Fi 8, etc. Note that Wi-Fi is a registered trademark.This may be applied to systems based on technologies such as IEEE 802.16 (WiMAX®), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth®, network virtualization technologies (e.g., NFV (Network Function Virtualization), SFC (Service Function Chaining), SDN (Software Defined Networking)), or LPWA (Low Power Wide Area). Furthermore, each aspect / embodiment described in this disclosure may be applied to systems based on a combination of at least two of these technologies. Of course, "based on" means not only systems that utilize the technology, but also systems that utilize extensions or modifications of the technology.

[0106] In this disclosure, any two terms selected from the set of terms such as "Base Station (BS)", "Radio Base Station", "Fixed Station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "Access Point (AP)", "Transmission Point (TP)", "Reception Point (RP)", "Transmission / Reception Point (TRP)", "Radio Unit (RU)", "Remote Unit (RU)", "Control Unit (CU)", "Distributed Unit (DU)", "Remote Radio Head (RRH)", "Node", "Gateway", "Ground Base Station", "Stratospheric Base Station", "Unmanned Aerial Vehicle", "High Altitude Platform Station (HAPS)", "Airborne Platform", "Panel", "Cell", "Radio Access Network (RAN)", and "Network" may be used interchangeably.

[0107] Each cell contained within a base station may be referred to as a macrocell, small cell, femtocell, picocell, serving cell, or supercell, among other terms. In this disclosure, any two terms selected from the set of terms such as “cell,” “sector,” “cell group,” “carrier,” “component carrier,” “cluster,” “bandwidth part (BWP),” and “carrier bandwidth” may be used interchangeably.

[0108] In this disclosure, any two terms selected from the set of terms such as "Mobile Station (MS)", "user terminal", "User Equipment (UE)", "Device", "module", and "Terminal" may be used interchangeably.

[0109] The terminal may be called a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, router (e.g., home router, mobile router, etc.), TCU (Telematics Control Unit), or some other appropriate term.

[0110] A base station and a terminal may each consist of one or more devices. Devices that constitute at least a part of each base station and terminal may be called transmitting devices, receiving devices, communication devices, etc. Furthermore, the devices constituting at least a part of each base station and terminal may be, but are not limited to, objects themselves such as vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, unmanned aerial vehicles, stratospheric base stations (e.g., High Altitude Platform Stations (HAPS)), artificial satellites (e.g., Low Earth Orbit (LEO) satellites, Middle Earth Orbit (MEO) satellites, Geostationary Earth Orbit (GEO) satellites), drones (registered trademark), multicopters, quadcopters, balloons, and IoT (Internet of Things) devices (e.g., smart meters, sensors), or include, but are not limited to, objects or devices mounted on such objects. Furthermore, the object in question may be a moving object (hereinafter referred to as a "moving object"; this does not exclude the possibility of the moving object being in a stationary state) or a fixedly positioned object (hereinafter referred to as a "non-moving object").

[0111] Furthermore, the term "base station" in this disclosure may be interpreted as "terminal." For example, the various aspects / embodiments of this disclosure may be applied to configurations in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.) or communication over a non-terrestrial network (NTN). In this case, the terminal 20 may have at least some of the functions of the base station 10 described above. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "sidelink") or terms corresponding to NTN (for example, feeder link or service link). For example, an uplink channel or a downlink channel may be interpreted as a sidelink channel.

[0112] Furthermore, this disclosure is also applicable when at least some of the equipment constituting the base station and terminal operates outside of the ground (for example, in the atmosphere or in outer space).

[0113] Furthermore, the term "terminal" in this disclosure may be interpreted as "base station." In this case, the base station 10 may be configured to have the same functions as the terminal 20 described above.

[0114] Information notification is not limited to the embodiments described herein and may be carried out by other means. For example, information notification may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block), SIB (System Information Block))), other signals, or at least two combinations thereof. Physical layer signaling may also be called L1 (Layer 1) control information. MAC signaling may be called, for example, a MAC control element (CE) or a MAC PDU (Protocol Data Unit). RRC signaling may also be called an RRC message or an information element (IE) within the RRC message. The RRC message may be a message used for, for example, controlling an RRC connection (e.g., setup, reconfiguration, establishment, reestablishment, release, or resume), mobility, measurement reporting, or notification of terminal capability, or it may be an information element within the message. Furthermore, the notification of information may be explicit or implicit. An explicit notification of information is the notification of the information itself, while an implicit notification of information may be the notification of information other than the information in question, or the fulfillment of certain conditions which constitutes notification of the information in question.Furthermore, notification of information may include not only notification between the same layer of different devices (e.g., between lower layers or upper layers of base station 10 and terminal 20), but also notification between different layers within the same or different devices (e.g., between lower and upper layers within base station 10 or terminal 20). Also, notification of information from one device to another may be carried out via one or more devices. With respect to any information described in this disclosure (e.g., variables, constants, parameters, settings), information indicating / specifying (or relating to) the value of such arbitrary information may be notified from any first device (e.g., terminal / base station) to any second device (e.g., base station / terminal), even if not specifically stated in the embodiments described above.

[0115] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be reordered, provided they are consistent. For example, the methods described in this disclosure present various step elements using exemplary order and are not limited to the specific order presented.

[0116] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node, or by a part of it (e.g., CU, RU, or DU). It is clear that various operations performed for communication with terminals in a RAN or core network may be performed by at least a part of the base station and other network nodes other than the base station. The other network nodes may be a single node or a combination of multiple nodes. A network node is, for example, a node provided in various core networks such as EPC (Evolved Packet Core) or 5GC (5G Core Network), and provides one or more network functions (NFs).

[0117] Furthermore, in this disclosure, the action of "a terminal receiving information from a base station" is accompanied by the actions of "a base station transmitting the information to the terminal," "a base station generating the information," or both. Similarly, the action of "a terminal transmitting information to a base station" is accompanied by the action of "a base station receiving the information from the terminal." In addition, actions such as "a terminal is configured to..." or "a terminal is configured to..." may include the actions of "a base station transmitting configuration information regarding the terminal's settings" and "the terminal setting a predetermined action based on the configuration information."

[0118] Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during execution.

[0119] The above description of the disclosure is illustrative, and the present invention is not limited to the embodiments described herein. The disclosure can be implemented as modified and altered forms without departing from the spirit of the invention. The disclosure and its modifications and altered forms are included within the scope of the present invention and its equivalents.

[0120] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0121] Radio resources can be defined by a combination of units of resources in one or more domains, such as the time domain, frequency domain, spatial domain, code domain, and power domain.

[0122] For example, resources in the time domain may be defined by one or more time units. These one or more time units include, but are not limited to, radio frames, subframes, slots, symbols, transmission time intervals (TTIs), or at least two combinations thereof. Furthermore, these time units may be fixed-length time units independent of numerology, variable-length time units dependent on numerology, or both. Examples of fixed-length time units include, but are not limited to, subframes consisting of one or more slots, and radio frames containing multiple subframes. Examples of variable-length time units include, but are not limited to, symbols and slots containing a fixed number of symbols. A certain time unit may be divided into shorter time units. Examples of shorter time units include, but are not limited to, mini-slots consisting of fewer symbols than the number of symbols that make up a slot. The time units described above may include, for example, time units used as units for scheduling, link adaptation, etc. Furthermore, any time unit in this disclosure may be interpreted as being interchangeable with other time units.

[0123] Numerology refers to parameters that define the physical layer structure, and may be parameters based on at least one of the following: subcarrier spacing (SCS), symbol length, cyclic prefix length, and sampling time.

[0124] Resources in the frequency domain may be defined, for example, by one or more frequency units. Such one or more frequency units may include, for example, subcarriers, resource blocks (RBs), bandwidth parts (BWPs), carrier bandwidths, or a combination of at least two of these, but the names of frequency units are not limited to these. Furthermore, the number of subcarriers included in a frequency unit may be a fixed number regardless of the neurology, or a variable number that changes depending on the neurology. For example, an RB consists of a predetermined number of consecutive subcarriers in the frequency domain, and the number of subcarriers included in the RB may be the same regardless of the neurology, for example, 12, but is not limited to this. Similarly, a BWP may consist of, for example, one or more consecutive RBs within a carrier bandwidth, but is not limited to this. For terminal 20, one or more BWPs may be set within one carrier, and at least one of the BWPs may be activated. Furthermore, any frequency unit in this disclosure may be interpreted as another frequency unit.

[0125] Furthermore, resources in both the time domain and the frequency domain may be defined, for example, by one or more time / frequency units composed of time units and frequency units. Such time / frequency units are, but are not limited to, resource elements (REs) consisting of one symbol and one subcarrier, resource element groups (REGs) consisting of a predetermined number of REs, and control resource sets (CORESETs) consisting of a predetermined number of symbols and a predetermined number of RBs.

[0126] Furthermore, resources in the spatial domain may be defined, for example, by one or more spatial units. Such spatial units include, but are not limited to, beams, MIMO (Multi Input Multi Output) layers, antenna ports, or at least two combinations thereof.

[0127] Furthermore, resources in the code domain may be defined, for example, by one or more code units. Such code units may be, but are not limited to, cyclic shifts (CS), orthogonal cover codes (OCC), or combinations thereof.

[0128] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0129] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0130] 10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device

Claims

1. A terminal comprising: a receiving unit that receives an RRC (Radio Resource Control) message containing information relating to the execution conditions of an inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) from a RAN (Radio Access Network) node of a first RAT; and a control unit that monitors whether the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, wherein the control unit performs an LTM handover to the RAN node of a second RAT if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied.

2. The terminal according to claim 1, wherein the control unit executes a random access procedure with the RAN node of the second RAT if the execution condition is satisfied within a period based on a parameter indicating the period until the execution condition is satisfied.

3. The terminal according to claim 1, wherein the control unit transmits a cell switching notification including the cell ID of the second RAT to the RAN node of the first RAT if the execution condition is satisfied within a period based on a parameter indicating the period until the execution condition is satisfied.

4. The terminal according to claim 1, wherein, upon receiving the RRC message, the control unit further receives a PDCCH (Physical Downlink Control Channel) order including the cell ID of the second RAT and transmits a RACH (Random Access Channel) preamble to the RAN node of the second RAT.

5. The terminal according to claim 1, wherein the control unit transmits the inter-RAT measurement result of the beam of the second RAT to the RAN node of the first RAT.

6. A communication method in which a terminal performs the following steps: receiving an RRC (Radio Resource Control) message containing information relating to the execution conditions of an Inter-RAT (Radio Access Technology) LTM (Lower layer Triggered Mobility) from a RAN (Radio Access Network) node of a first RAT; monitoring whether the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied; and, if the execution conditions are satisfied within a period based on a parameter indicating the period until the execution conditions are satisfied, performing an LTM handover to a RAN node of a second RAT.

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