Communication method and user equipment

Abstract

A communication method according to the present invention, which is executed by user equipment in a mobile communication system supporting L1 / L2-Triggered Mobility (LTM), includes: performing event evaluation as to whether or not an event condition for transmitting a measurement report Medium Access Control (MAC) Control Element (CE) to a network node is satisfied, the measurement report MAC CE having stored therein a beam measurement value obtained by measuring the wireless quality of a beam; in response to the event condition being satisfied, performing priority ranking processing for selecting, according to prescribed priority ranks, a beam measurement value to be stored in the measurement report MAC CE among a plurality of beam measurement values obtained by wireless quality measurement; and performing transmission processing for transmitting, to the network node, the measurement report MAC CE having stored therein the beam measurement value selected through the priority ranking processing.

Description

Communication method and user device

[0001] This disclosure relates to a communication method and user equipment used in a mobile communication system.

[0002] The 3GPP (3rd Generation Partnership Project) (registered trademark; hereinafter the same) defines the technical specifications for NR (New Radio), a fifth-generation (5G) wireless access technology. In 3GPP mobile communication systems, the switching of serving cells (serving cell change) of a user device in a Radio Resource Control (RRC) connected state is instructed by sending an RRC layer message (a so-called handover command) corresponding to Layer 3 (L3) from the network node to the user device.

[0003] Meanwhile, in 3GPP Release 18, a technical specification for LTM (L1 / L2-Triggered Mobility), a new procedure for serving cell switching, has been established. LTM is a procedure in which a network node receives a Layer 1 (L1) measurement report from a user device, and based on that, the network node signals a cell switching command to the user device via a Media Access Control (MAC) control element (CE), thereby changing the serving cell of the user device.

[0004] 3GPP Technical Specification "3GPP TS 38.300 V18.2.0"

[0005] This disclosure provides technology for improving LTM.

[0006] A communication method according to a first aspect of this disclosure is a communication method performed by a user device in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), and includes: performing an event evaluation to determine whether an event condition has been met for transmitting a measurement report MAC (Medium Access Control) CE (Control Element) containing beam measurement values ​​obtained by radio quality measurement of a beam to a network node; performing a prioritization process to select beam measurement values ​​from a plurality of beam measurement values ​​obtained by radio quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order, in response to the event condition being met; and performing a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to the network node.

[0007] A user device according to a second aspect of this disclosure is a user device used in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), comprising: a control unit that performs an event evaluation to determine whether an event condition has been met for transmitting a measurement report MAC (Medium Access Control) CE (Control Element) containing beam measurement values ​​obtained by radio quality measurement of a beam to a network node, and performs a prioritization process to select beam measurement values ​​from a plurality of beam measurement values ​​obtained by radio quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order; and a transmission unit that performs a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to a network node.

[0008] This figure shows an example configuration of a mobile communication system according to an embodiment. This figure shows an example configuration of a UE (User Equipment) according to an embodiment. This figure shows an example configuration of a gNB (Network Node) according to an embodiment. This figure shows the configuration of the protocol stack of the wireless interface of the user plane that handles data. This figure shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals). This figure shows the configuration related to measurement by the UE according to an embodiment. This figure shows an example of a cell switching procedure by LTM in an intraCU (i.e., within the same gNB) according to an embodiment. This figure shows an example of an L1 measurement report for an event trigger according to an embodiment. This figure is for explaining the types of beams according to an embodiment. This figure shows an example of a UL MAC PDU according to an embodiment. This figure shows an overview of operation example 1 of the UE according to an embodiment. This figure shows an overview of operation example 2 of the UE according to an embodiment. This figure shows an overview of operation example 2 of the UE according to an embodiment. This figure shows an example configuration 1 of the measurement report MAC CE according to an embodiment. This figure shows an example operation of the mobile communication system 1 according to an embodiment. This figure shows an example configuration 2 of the measurement report MAC CE according to an embodiment. This figure shows an example configuration 3 of the measurement report MAC CE according to an embodiment. This figure shows an example configuration 4 of the measurement report MAC CE according to an embodiment. This figure shows an example configuration 5 of the measurement reporting MAC CE according to the embodiment.

[0009] A mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0010] (1) The mobile communication system configuration diagram 1 is a diagram showing an example of the configuration of the mobile communication system 1 according to this embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. In the following explanation, 5GS will be used as an example, but the mobile communication system may also have an LTE (Long Term Evolution) system applied to it at least partially, or a 6th Generation (6G) system applied at least partially.

[0011] The mobile communication system 1 comprises User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20. Hereinafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as core network (CN) 20. RAN 10 and CN 20 constitute the network 5 of the mobile communication system 1.

[0012] UE100 is a mobile wireless communication device. UE100 can be any device used by a user. For example, UE100 can be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or a device attached to a sensor, a vehicle or a device attached to a vehicle (Vehicle UE), or an aircraft or a device attached to an aircraft (Aerial UE). The link from UE100 to network 5 in the transmission direction is called the uplink (UL), and the link from network 5 to UE100 in the transmission direction is called the downlink (DL).

[0013] NG-RAN10 includes a base station (referred to as "gNB" in the 5G system) 200, which is a type of network node. The gNBs 200 are interconnected via the Xn interface, which is an inter-base station interface. The gNBs 200 manage one or more cells. The gNBs 200 perform wireless communication with UEs 100 that have established a connection with their own cell. The gNBs 200 have radio resource management (RRM) functions, user data (hereinafter simply referred to as "data") routing functions, measurement and control functions for mobility control and scheduling, etc. "Cell" is used as a term to indicate the smallest unit of a wireless communication area. "Cell" is also used as a term to indicate a function or resource that performs wireless communication with a UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0014] Furthermore, gNBs can also connect to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also connect to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0015] The 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE100. The AMF manages the mobility of the UE100 by communicating with it using NAS (Non-Access Stratum) signaling. The UPF controls data transfer. The AMF and UPF are connected to the gNB200 via the NG interface, which is the base station-core network interface.

[0016] Figure 2 shows an example configuration of UE100 (user device) according to this embodiment. UE100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit 140 that performs wireless communication with gNB200.

[0017] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130.

[0018] The transmitting unit 120 performs various types of transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 130 into a wireless signal and transmits it from the antenna.

[0019] The control unit 130 performs various control and processing operations in the UE 100. Such processing includes processing in each layer described later. The operation of the UE 100 described above and later may also be controlled by the control unit 130. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing operations.

[0020] Figure 3 shows an example configuration of a gNB200 (network node) according to this embodiment. The gNB200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a network communication unit 240. The transmitting unit 210 and the receiving unit 220 constitute a wireless communication unit 250 that performs wireless communication with the UE100. The network communication unit 240 includes a transmitting unit 241 that performs transmission and a receiving unit 242 that performs reception.

[0021] The transmitting unit 210 performs various types of transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a wireless signal and transmits it from the antenna.

[0022] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0023] The control unit 230 performs various control and processing operations in the gNB 200. Such processing includes processing in each layer described later. The operation of the gNB 200 described above and later may also be controlled by the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, decoding, etc. of the baseband signal. The CPU executes programs stored in memory and performs various processing operations.

[0024] The network communication unit 240 is connected to an adjacent base station via the Xn interface, which is an inter-base station interface. The network communication unit 240 is connected to the AMF / UPF 300 via the NG interface, which is an inter-base station-core network interface. The gNB 200 may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected by the F1 interface, which is a front-haul interface.

[0025] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0026] The user plane radio interface protocol consists of a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0027] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on the physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from gNB200 has a CRC (Cyclic Redundancy Check) parity bit added, which is scrambled by the RNTI.

[0028] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ: Hybrid Automatic Repeat reQuest), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of gNB200 via the transport channel. The MAC layer of gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0029] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of gNB200 via a logical channel.

[0030] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0031] The SDAP layer maps IP flows, which are the units under which the core network performs QoS (Quality of Service) control, to wireless bearers, which are the units under which the AS (Access Stratum) performs QoS control. Note that if the RAN is connected to the EPC, the SDAP is not required.

[0032] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0033] The protocol stack of the control plane's wireless interface includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 4.

[0034] RRC signaling for various settings is transmitted between the RRC layer of the UE100 and the RRC layer of the gNB200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of the UE100 and the RRC of the gNB200, the UE100 is in the RRC idle state. If the connection between the RRC of the UE100 and the RRC of the gNB200 is suspended, the UE100 is in the RRC inactive state.

[0035] The NAS layer (also simply referred to as "NAS"), located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the NAS layer of the UE100 and the NAS layer of the AMF300A. The UE100 also has an application layer in addition to the wireless interface protocol. Furthermore, the layer below the NAS layer is called the AS layer (also simply referred to as "AS").

[0036] (2) Measurement by UE The UE 100 in the RRC connected state measures at least one beam of the cell, and derives the radio quality of the cell by averaging the measurement results (power values). At this time, the UE 100 is set to consider a subset of the detected beams.

[0037] Here, filtering for measurement averaging is performed at two different levels. The UE 100 first derives the beam quality by L1 filtering which is filtering at the physical layer (PHY, layer 1 (L1)), and then derives the cell quality from a plurality of beams by L3 filtering which is filtering at the RRC layer (layer 3 (L3)) level. Note that the cell quality from beam measurement is derived in the same way for both the serving cell and non-serving cells. The UE 100 may include the measurement results of X best beams in the L3 measurement report according to the setting by the gNB 200.

[0038] FIG. 6 is a diagram showing a configuration related to the measurement by the UE 100.

[0039] The control unit 130 of the UE 100 includes an L1 filter 11, a beam integration / selection unit 12, an L3 filter 13, an evaluation unit 14, an L3 beam filter 15, and a beam selection unit 16.

[0040] The L1 filter 11 includes K L1 filters 11 corresponding to K beams. The L1 filter 11 receives K beam measurement values A obtained by the UE 100 (reception unit 110) measuring the radio quality for each of the K beams. The K beam measurement values A of the K beams are measurement values inside the physical layer (beam-specific samples), and are measurement values of the SSB (SS / PBCH block) or CSI (Channel State Information) reference signal resource detected by the UE 100 (reception unit 110) at L1. The L1 filter 11 performs L1 filtering on the K measurement values A of the K beams at L1, and outputs the beam-specific measurement value A after L1 filtering １ to the beam integration / selection unit 12 and the L3 beam filter 15.

[0041] The beam integration / selection unit 12 integrates the measurement value A specific to the beam １ to derive the radio quality (Cell quality) B of the cell, and outputs the cell quality B to the L3 filter 13. The operation setting of the beam integration / selection unit 12 is provided by RRC signaling from the gNB 200.

[0042] The L3 filter 13 performs filtering at L3 on the measurement value (cell quality B) output by the beam integration / selection unit 12, and outputs the measured value C after L3 filtering to the evaluation unit 14. The operation setting of the L3 filter 13 is provided by RRC signaling from the gNB 200. The measured value C after L3 filtering is used as an input for one or more evaluations of the L3 measurement report from the UE 100 to the gNB 200.

[0043] The L3 filter 13 filters the measurement results for each cell measurement quantity and each beam measurement quantity by the following formula (1) before evaluating the reporting criteria or using them in the L3 measurement report: F ｎ =(1 - a)×F ｎ－１ + a×M ｎ ...(1) Here, M ｎ is the latest measurement result from the physical layer (L1). F ｎ is the updated filtered measurement result, which is used for evaluating the reporting criteria or the L3 measurement report. F ｎ－１ is the old filtered measurement result, and when receiving the first measurement result from the physical layer (L1), F ０ is set to M １ .

[0044] When MeasObjectNR is set in RRC, a = 1 / 2 （ｋｉ／４） is used. Here, k ｉ is the filter coefficient (filterCoefficient) of the corresponding measurement quantity of the i-th QuantityConfigNR in the quantityConfigNR-List, and i is indicated by the quantityConfigIndex in MeasObjectNR. For other measurement values, a = 1 / 2 （ｋ／４）Here, k is the filter coefficient of the corresponding measured quantity received by quantityConfig.

[0045] The L3 filter 13 adapts the filter so that the filter's time characteristics are preserved at different input rates, assuming a sample rate where the filter coefficient k is equal to X milliseconds. The value of X corresponds to the L1 measurement period within one frequency assuming non-DRX operation and is frequency range dependent.

[0046] Note that if the filter coefficient k is set to 0 (zero), L3 filtering will not be applied.

[0047] The evaluation unit 14 evaluates whether an L3 measurement report D to the gNB200 is necessary. This evaluation can be performed based on multiple measurement flows at a reference point C, for example, a comparison of different measurement values. This is done by comparing input C and input C １ This is shown. The evaluation unit 14 determines that at least the new measurement results are at points C, C １ Each time a report is made, an event evaluation corresponding to the reporting criteria is performed. The setting of the reporting criteria is provided by RRC signaling from gNB200. L3 Measurement Report D represents the measurement report information (RRC message) sent from UE100 to gNB200. L3 Measurement Report D includes the measurement ID of the associated measurement setting that triggered the report.

[0048] The L3 beam filter 15 measures k values ​​A １ (That is, beam-specific measurements) are filtered on a beam-by-beam basis, and k measurement values ​​E (that is, beam-specific measurements) are output to the beam selection unit 16. The measurement values ​​E are used as input for selecting X measurement values ​​to be reported.

[0049] The beam selection unit 16 selects X measurement values ​​F from k measurement values ​​E and outputs the X measurement values ​​F. The X measurement values ​​F are beam measurement information included in the measurement report information (RRC message) transmitted from UE100 to gNB200.

[0050] (3) Overview of LTM Mobile communication system 1 supports LTM (L1 / L2-triggered mobility).

[0051] In a typical handover procedure, the serving cell switch is triggered by signaling at the higher layer, L3, specifically the RRC layer. This type of typical handover is also called an L3 handover. In an L3 handover, an RRC message, specifically an L3 Measurement Report (MR) message, is sent from UE100 to gNB200. Based on this Measurement Report message, gNB200 decides to hand over UE100 and instructs the cell switch by sending a handover command (specifically, an RRC Reconfiguration message) from gNB200 to UE100.

[0052] On the other hand, LTM is a technique for reducing mobility delays (specifically, serving cell switching delays) compared to general handover procedures by triggering serving cell switching through signaling at the lower layers, Layer 1 (L1) and / or Layer 2 (L2). In LTM, the gNB200 receives an L1 measurement report from the UE100, and based on this, the gNB200 instructs the UE100 to switch serving cells by signaling a cell switching command via MAC CE.

[0053] Specifically, in LTM, firstly, gNB200 prepares LTM settings for candidate cells to be switched to, and provides LTM settings to UE100 via RRC signaling.

[0054] Secondly, UE100 performs synchronization with LTM candidate cells through early sync.

[0055] Thirdly, the gNB200 receives the L1 measurement report from the UE100, decides to switch the serving cell to the target cell based on the L1 measurement report, and sends a Cell Switch Command indicating the target cell (LTM setting) to the UE100 via the MAC control element (CE). The serving cell switching trigger is transmitted by the MAC CE, which includes at least a candidate setting index (ID) along with the beam indicator.

[0056] Fourthly, the UE100 switches the serving cell in response to the MAC CE cell switching command from the gNB200 (source cell).

[0057] Thus, the gNB200 triggers a serving cell switch by selecting the LTM setting as the target setting. The LTM setting can be added, modified, and released by the gNB200 via RRC signaling.

[0058] The following principles apply to LTM:

[0059] Each LTM setting can be provided as a differential setting (delta setting) relative to a baseline setting used to form the complete LTM setting.

[0060] - When the full LTM configuration is applied, the current UE configuration is replaced when the serving cell switches. The reconfiguration procedure performs the replacement, but does not necessarily reset the MAC, RLC, or PDCP layers.

[0061] - The user plane will continue without resetting if configured with RRC signaling, in order to avoid additional delays in data recovery.

[0062] - Security updates are not provided in LTM versions.

[0063] - LTMs between subsequent LTM settings can be executed without RRC reconfiguration. In other words, the UE100 does not release other LTM settings after an LTM has been triggered.

[0064] Figure 7 shows an example of a cell switching procedure by LTM within an intraCU (i.e., within the same gNB200). In the illustrated example, UE100 performs a serving cell switch from the first cell to the second cell of gNB200.

[0065] Here, the first cell and the second cell may be formed by different TRPs (Transmission and Reception Points). In the following description of the embodiments, the second cell will also be referred to as the "LTM candidate cell (or candidate cell)" until the LTM decides to switch the serving cell, and the second cell will also be referred to as the "target cell" after the LTM decides to switch the serving cell. The first cell will also be referred to as the "source cell" or the "(current) serving cell".

[0066] In step S1, UE100 is in an RRC connected state in the cell of gNB200 (the first cell).

[0067] In step S2, UE100 sends a Measurement Report message, which is an RRC message, to gNB200 (the first cell). The Measurement Report sent via RRC message is also referred to as the "L3 Measurement Report".

[0068] In step S3, gNB200 decides to use LTM based on the Measurement Report message and begins preparing the LTM candidate cell.

[0069] In step S4, gNB200 (the first cell) sends an RRC message, specifically an RRC Reconfiguration message, to UE100 containing the LTM Candidate Configurations of one or more LTM candidate cells. The LTM configuration may include a Random Access Channel (RACH) configuration used for sending RA preambles to the corresponding LTM candidate cells, such as a Conflict-Free Random Access (CFRA) configuration. Such a RACH configuration may be referred to as an Early Ul Sync Configuration. CFRA is a random access procedure in which UE100 is allocated dedicated RACH resources (e.g., dedicated preamble sequences and / or dedicated time and frequency resources) and no RACH conflicts occur between UE100s.

[0070] In step S5, UE100 saves the LTM configuration and sends an RRC Reconfiguration Complete message to gNB200 (the first cell).

[0071] In step S6, UE100 may perform synchronization with the LTM candidate cell (second cell) before receiving the cell switching command MAC CE from the first cell. Such synchronization may be called Early Sync. Here, UE100 may perform Downlink Synchronization (DL Synchronization) with the LTM candidate cell and then perform Early Timing Advance (TA) acquisition (i.e., UL Early Sync) with the LTM candidate cell requested by gNB200 (serving cell). This is performed by a CFRA triggered by a PDCCH order from the first cell. Note that if DCI Format 1_0 is used and all "Frequency domain resource assignment" fields in the DCI are set to "1", the DCI is treated as a PDCCH order. Furthermore, if Early Ul Sync Config is set on UE100, the PDCCH order may include a cell indicator that indicates the corresponding RACH transmission cell, i.e., which LTM candidate cell UE100 should send a random access preamble (RA preamble) to.

[0072] UE100 transmits an RA preamble to the designated LTM candidate cell (second cell). To minimize the interruption of serving cell communication by CFRA to the LTM candidate cell, during early synchronization, UE100 does not receive a Random Access Response (RAR) from the LTM candidate cell for the purpose of obtaining the TA value. The TA value of the LTM candidate cell (target cell) is indicated by the cell switching command MAC CE in step S9. The TA value is used to adjust the uplink transmission timing of UE100.

[0073] In step S7, UE100 performs Layer 1 (L1) measurements on the configured LTM candidate cell and transmits a physical layer measurement report (also referred to as the "L1 measurement report") to gNB200 (the first cell). The L1 measurement report is transmitted and received at L1, which is the PHY layer. For example, UE100 transmits L1-RSRP and / or L1-SINR to gNB200 via PUCCH (Physical Uplink Control Channel) and / or PUSCH (Physical Uplink Shared Channel).

[0074] In step S8, the gNB200 decides to switch the serving cell to the target cell (second cell).

[0075] In step S9, gNB200 (the first cell) sends a cell switching command MAC CE to UE100, which includes a candidate setting index for the target cell. The cell switching command MAC CE may include a TA value obtained by UL early synchronization (i.e., a TA value derived based on the RA preamble).

[0076] In step S10, UE100 switches to the settings for the target cell (second cell). Specifically, UE100 detaches from the first cell and applies the settings for the target cell (second cell).

[0077] In step S11, if the serving cell switch requires the execution of a random access procedure (for example, if the cell switch command MAC CE does not contain a valid TA value), UE 100 executes a random access procedure on the target cell (RACH (Random Access Channel) based LTM cell switch). However, if UE 100 does not need to obtain the TA of the target cell during the serving cell switch (for example, if the cell switch command MAC CE contains a valid TA value), the random access procedure can be skipped (RACH-less LTM cell switch).

[0078] In step S12, UE100 indicates that the serving cell switch to the target cell has been successfully completed, for example, by sending an RRC Reconfiguration Complete message to the target cell (the second cell). Subsequently, UE100 may perform steps S6 to S12 multiple times for subsequent LTM serving cell switches based on the settings provided in step S4.

[0079] (4) Basic Operation Example Regarding L1 Measurement Report Based on the above configuration and operation, a basic operation example regarding the L1 measurement report according to the embodiment will be described.

[0080] As described above, in LTM, the gNB200 performs LTM-related control (also referred to as "LTM control") based on the L1 measurement report from the UE100. For example, the gNB200 selects a target beam (and / or target cell) based on the L1 measurement report and triggers an LTM cell switch for the selected target. Furthermore, the gNB200 may select a candidate beam (and / or target cell) to trigger early synchronization based on the L1 measurement report.

[0081] The L1 measurement results included in the L1 measurement report include the reference signal received power (RSRP). Such an RSRP is also called L1-RSRP. There are two types of L1-RSRP: SS-RSRP, which is obtained by measuring the SSB as the reference signal, and CSI-RSRP, which is obtained by measuring the CSI-RS as the reference signal. SS-RSRP is defined as the linear average of the power levels (in [W]) of the resource elements carrying the secondary synchronization signal (SSS). The measurement time resources for SS-RSRP are limited to the SS / PBCH block measurement time setting (SMTC) window period. When SS-RSRP is used as the L1-RSRP by the reporting settings, the limitation of measurement time resources by the SMTC window period may not apply. On the other hand, CSI-RSRP is defined as the linear average of the power levels (in watts) of resource elements of the antenna port carrying the CSI reference signal set up for RSRP measurement, over set CSI-RS opportunities within the measurement frequency band under consideration.

[0082] 3GPP Release 18 envisions the use of periodic L1 measurement reports. Such periodic L1 measurement reports may require the UE100 to transmit L1 measurement reports at a high transmission frequency, potentially increasing the load on the UE100 (power consumption, etc.). On the other hand, 3GPP Release 19 is considering the introduction of event-triggered L1 measurement reports (also referred to as "event-triggered L1 measurement").

[0083] In event-triggered L1 measurements, the use of beam-level measurement results for event evaluation is fundamental. However, event-triggered L1 measurements may also be performed at the cell level. In event-triggered L1 measurement reports, UE100 transmits an L1 measurement report to gNB200 when the radio quality conditions (also referred to as "entering conditions" or "first radio quality conditions") corresponding to the L1 LTM measurement event are met. In other words, in event-triggered L1 measurement reports, UE100 does not need to transmit an L1 measurement report during periods when the set radio quality conditions are not met, thus reducing the load on UE100. UE100 also performs an LTM event evaluation at L1 or L2, which evaluates whether the L1 LTM measurement event has been met. Furthermore, UE100 transmits the L1 measurement report at L1 or L2.

[0084] L1 LTM measurement events may support beam-specific quality-based events such as: - Event LTM1: The serving cell's beam is better than the absolute threshold; - Event LTM2: The serving cell's beam is worse than the absolute threshold; - Event LTM3: The LTM candidate cell's beam is better than the serving cell's beam by a certain offset; - Event LTM4: The LTM candidate cell's beam is better than the absolute threshold; - Event LTM5: The serving cell's beam is worse than absolute threshold 1, and the LTM candidate cell's beam is better than another absolute threshold 2.

[0085] Furthermore, the UE100 uses either a beam from the serving cell or an adjacent cell for event evaluation. The L1 measurement resource settings in the LTM configuration support SSB and CSI-RS beam configurations. For event LTM3 and event LTM5, the same reference signal type is used for the serving cell and adjacent cells. Also, the L1 measurement results included in the L1 measurement report, as shown in Figure 6, are beam-specific measurement values ​​A after L1 filtering. １ That's fine.

[0086] Figure 8 shows an example of an L1 measurement report for an event trigger according to the embodiment. In the illustrated example, it is assumed that event LTM4 is set from gNB200 to UE100 as the L1 LTM measurement event.

[0087] The UE100 evaluates (determines) whether the L1 wireless quality conditions (entering conditions, leaving conditions) corresponding to the set L1 LTM measurement event have been met. Hereinafter, these L1 wireless quality conditions will also be referred to as "L1 event conditions" and "L1 events." Note that "meeting the event conditions" is synonymous with "meeting the entering conditions" or "entering into the event," and "not meeting the event conditions" is synonymous with "meeting the leaving conditions" or "leaving from the event." The state in which the event conditions are met (i.e., the state in which the entering conditions are met) will also be referred to as the "entered state," and the state in which the event conditions are not met (i.e., the state in which the leaving conditions are met) will also be referred to as the "leaved state."

[0088] When a UE100 receives an L1 LTM measurement event from gNB200, it sends an L1 measurement report to gNB200 when the entering conditions corresponding to the L1 LTM measurement event are met. The entering conditions may also be conditions in which a hysteresis value (offset value) is assigned to the reference value (threshold) in the L1 LTM measurement event.

[0089] Such L1 measurement reports may be periodic L1 measurement reports. That is, UE100 may start transmitting periodic L1 measurement reports when the entering conditions corresponding to the set L1 LTM measurement event are met.

[0090] By receiving an L1 measurement report triggered by such an event, the gNB200 can determine that the entering condition has been met in the UE100 and, for example, initiate LTM control. It is also desirable that the gNB200 be able to determine when the L1 LTM measurement event is no longer met in the UE100. If the gNB200 can determine that the L1 LTM measurement event is no longer met in the UE100, it can, for example, terminate LTM control, which could enable appropriate and efficient LTM control.

[0091] UE100 starts (triggers) the transmission of periodic L1 measurement reports when the entering condition is met. At least one of the following can be set for UE100: hysteresis value (offset value), TTT (Time To Trigger), reporting interval (reportInterval), and reporting amount (reportAmount). If TTT is set, UE100 may start (trigger) the transmission of L1 measurement reports in accordance with the duration that the first radio quality condition (entering condition) has been met for the TTT time. If reporting interval (reportInterval) is set, UE100 may transmit L1 measurement reports at a frequency corresponding to the reporting interval (reportInterval). If reporting amount (reportAmount) is set, UE100 may transmit L1 measurement reports a number of times corresponding to the reporting amount (reportAmount).

[0092] On the other hand, when the radio quality conditions corresponding to the L1 LTM measurement event (also referred to as "leaving conditions" or "second radio quality conditions") are met, the transmission of periodic L1 measurement reports may be terminated. The leaving conditions may be conditions to which a hysteresis value (offset value) is assigned to the reference value (threshold, etc.) in the L1 LTM measurement event. Therefore, if gNB200 is unable to receive periodic L1 measurement reports from UE100, it can be inferred that the leaving conditions have been met at UE100.

[0093] 3GPP Release 19 considers evaluating the TTT (Threshold Time) entry conditions for each beam. That is, when multiple beams are measured simultaneously, the measurement results will only be reported for beams that meet the TTT conditions. TTT is also applicable to the leaving conditions (second radio quality condition).

[0094] The gNB200 can set the type of reference signal used for LTM event evaluation. The gNB200 includes the reference signal type setting in the LTM setting and provides it to the UE100 via RRC signaling. The reference signal types are classified according to the beam type and include two types: an SSB (Synchronization Signal Block) reference signal corresponding to an SSB beam, and a CSI-RS (Channel State Information-Reference Signal) corresponding to a CSI-RS beam. In the LTM setting, the gNB200 can set either a CSI-RS beam or an SSB beam as the candidate beam. Figure 9 is a diagram illustrating the beam types according to the embodiment. As shown in Figure 9, there are two types of beams included in the Serving Cell and Candidate Cell, respectively: an SSB beam and a CSI-RS beam. In each cell, the two types of beams are grouped according to the QCL (Quasi-Colocation) information that gNB200 notifies UE100 of via the TCI (Transmission Configuration Indication) state.

[0095] QCL information is information about the positional relationship between the antennas of the gNB200, indicating how close the multiple antennas are positioned. This information can be used by the UE100 to estimate characteristics such as phase and / or delay when processing the received signal. QCL is mainly used for the following purposes: ・Channel estimation: The UE100 uses information about the positional relationship between the antennas of the gNB200 to accurately estimate the phase and / or delay of the received signal. With QCL information, more accurate channel estimation is possible, improving reception performance. ・Frequency offset estimation: The UE100 uses QCL information to estimate the frequency offset of the signal received from the gNB200. With QCL information, more accurate frequency offset estimation is possible, improving synchronization performance. ・Synchronization: The UE100 uses QCL information to establish synchronization with the gNB200. With QCL information, more accurate synchronization is possible, improving communication stability.

[0096] In an event-triggered L1 measurement, the UE100 measures a candidate beam of the same type as the candidate beam type set by the gNB200. For example, if the gNB200 sets the candidate beam type of an LTM candidate cell to CSI-RS, the UE100 will measure the CSI-RS beam of the serving cell grouped by the same QCL information as the currently used SSB beam, even if the beam type used for communication with the serving cell is SSB. Also, in an event-triggered L1 measurement, if the gNB200 sets the candidate beam type of an LTM candidate cell to, for example, CSI-RS, the UE100 will measure the CSI-RS beam of the candidate cell.

[0097] UE100 can transmit event-triggered L1 measurement reports to gNB200 via MAC CE in the available area of ​​MAC PDU (Protocol Data Unit). The MAC CE containing the L1 measurement report is referred to as the measurement report MAC CE. In the measurement report MAC CE, the candidate beam identification information (ID) may be SSBRI (SSB Reference signal Beam Identifier) ​​or CRI (CSI-RS Resource Indicator). In addition, the L1 measurement report contains two types of beam measurement values: SSB and CSI-RS (Channel State Information-Reference Signal). Beam measurement values ​​using the SSB reference signal are SSB type beam measurement values, and beam measurement values ​​using CSI-RS are CSI-RS type beam measurement values. The two types of beam measurements, SSB and CSI-RS, may be stored in a single measurement report MAC CE.

[0098] A MAC PDU is a unit of data exchanged in the MAC layer, and is a byte-aligned (for example, aligned to octet boundaries) bit sequence. Figure 10 shows an example of an uplink (UL) MAC PDU according to an embodiment. The UL MAC PDU includes one or more MAC subPDUs, as shown in Figure 10. The configuration of a MAC subPDU can be one of the following patterns: MAC subPDU patterns: ・A MAC subheader + a MAC SDU (Service Data Unit) ・A MAC subheader + a MAC CE ・A MAC subheader + padding area ・A MAC subheader (including padding area) only Here, the MAC SDU (Service Data Unit) is an RLC PDU (RLC Protocol Data Unit) passed from the RLC layer. The padding area is the free space located at the end of the MAC PDU.

[0099] The above MAC subheader format is one of the following formats: • R / F / LCID / (eLCID) / L: A general MAC subheader format. • (LX) / R / LCID / (eLCID): A format used for fixed-size MAC CEs and / or padding. • (LX) / R / LCID: A format used for MAC SDUs including UL CCCH (Uplink Common Control Channel). Here, LCID (Logical Channel ID) indicates the identification information of the logical channel. F (Format) indicates the MAC subheader format. L (Length) indicates the length of the MAC SDU or MAC CE. R / F are reserved bits or bits used for future extensions. eLCID (extended LCID) is a field for extending the LCID.

[0100] As shown in Figure 10, in the UL MAC PDU, the MAC subPDU containing the MAC CE is placed after all MAC subPDUs, including the MAC SDU, and before the MAC subPDU containing the padding area. The measurement report MAC CE of this disclosure is stored in the empty area contained in the MAC subPDU at the end of the MAC PDU, i.e., the padding area. For this reason, the empty area of ​​the MAC PDU is also referred to as the "padding area".

[0101] There is a limit to the maximum size (TBS: Transport Block Size) of the MAC PDU allocated to UE100. Therefore, if the size of the measurement report MAC CE is larger than the available space in the MAC PDU, it may not be possible to transmit the entire measurement report MAC CE. In such cases, UE100 transmits a portion of the measurement report MAC CE using the available space in the MAC PDU, discarding the remaining portion, or transmitting it in the next MAC PDU. Specifically, UE100 stores a number of beam measurement values ​​that can be stored in the available space of the MAC PDU into a truncated measurement report MAC CE (a smaller version of the normal measurement report MAC CE) corresponding to the size of the available space in the MAC PDU, and transmits it. Therefore, the challenge lies in determining which beam measurement values ​​to store in the truncated measurement report MAC CE, and based on what criteria.

[0102] Furthermore, similar issues arise not only when sending a truncated measurement report MAC CE, but also when UE100 cannot store all beam measurement values ​​in the measurement report MAC CE. Specifically, for example, gNB200 sets the number of measurement beams that can be stored in the measurement report MAC CE (report beam capacity) to "M", includes the report beam capacity setting in the LTM setting, and sends it to UE100 via RRC signaling. In this case, only beam measurement values ​​less than or equal to M can be stored in the measurement report MAC CE. For example, if the number of beam measurement values ​​that satisfy the entering conditions measured by UE100 exceeds M, and not all beam measurement values ​​can be stored in the measurement report MAC CE, the same issues as described above will occur.

[0103] Furthermore, the gNB200 can also be configured to allow the storage of beam measurement values ​​that do not meet the enterring conditions in the measurement report MAC CE. For example, the gNB200 can be configured to allow the storage of beam measurement values ​​that do not meet the enterring conditions in the measurement report MAC CE. Also, the number of beams measured by the UE100 that meet the enterring conditions is less than M. In this case, the same problem as described above occurs when the UE100 attempts to store beam measurement values ​​that do not meet the enterring conditions in the remaining storage space after storing all beam measurement values ​​that meet the enterring conditions in the measurement report MAC CE.

[0104] Furthermore, the gNB200 can also set the maximum number of beams that can be reported to the UE100 (maximum reportable beam count). For example, the gNB200 sets the maximum reportable beam count to "N", includes it in the LTM setting, and transmits it to the UE100 via RRC signaling. If the number of measured beams that satisfy the entering conditions measured by the UE100 exceeds the maximum reportable beam count N, the same problem as described above will occur.

[0105] Therefore, in the embodiments described in (4.1) and (4.2) below, event-triggered LTM measurement is introduced, and the operation of UE100 to identify beam measurement values ​​in order to achieve optimal reporting (transmission) when it is not possible to transmit all beam measurement values ​​that satisfy the entering condition, or all beam measurement values ​​measured by UE100 to gNB200, is described. In the following description, each example of operation of UE100 is described when beam measurement values ​​are stored in the measurement report MAC CE, but each example of operation of UE100 can also be applied when beam measurement values ​​are stored in the truncated measurement report MAC CE.

[0106] In this embodiment, firstly, UE 100 performs an event evaluation to determine whether the event conditions for transmitting a measurement report MAC CE containing beam measurement values ​​obtained from wireless quality measurement to gNB 200 have been met. Secondly, depending on whether the event conditions have been met, UE 100 performs a prioritization process to select beam measurement values ​​from among a plurality of beam measurement values ​​obtained from wireless quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order. Thirdly, UE 100 performs a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to gNB 200.

[0107] Here, the beam measurement values ​​obtained by the radio quality measurement of the beam are the measured radio quality values ​​for the SSB (SS / PBCH block) or CSI (Channel State Information) reference signal detected by UE100 from each of the candidate beams set by gNB200. The event evaluation to determine whether the event conditions for transmitting the measurement report MAC CE to gNB200 have been met is an evaluation (determination) by UE100 of whether the L1 radio quality conditions (entering conditions, leaving conditions) corresponding to the set L1 LTM measurement event (any of event LTM1 to event LTM5) have been met.

[0108] The predetermined priority order may, depending on the circumstances, be one or more of the following priorities (a) to (e).

[0109] (a) Prioritizing beam measurement values ​​in descending order. Here, the predetermined priority is to store the beam measurement values ​​in the measurement report MAC CE in descending order of value. Examples of beam measurement values ​​include RSRP, SINR (Signal to Interference plus Noise Ratio), RSRQ (Reference Signal Received Quality), etc. By prioritizing beam measurement values ​​in descending order, beams with good communication quality can be detected preferentially.

[0110] (b) Prioritizing beam measurement values ​​that satisfy the event conditions Here, the predetermined priority is to prioritize storing beam measurement values ​​that satisfy the event conditions in the event evaluation in the measurement report MAC CE. By prioritizing the reporting of beams that satisfy the event conditions, important information is quickly transmitted to the gNB200 when an event occurs, allowing the gNB200 to understand the situation and take appropriate action. After prioritizing the storage of beam measurement values ​​that satisfy the event conditions in the measurement report MAC CE, the UE100 may, if there is sufficient storage space, also store beam measurement values ​​that do not satisfy the event conditions in the measurement report MAC CE. Alternatively, the UE100 may, for example, store only beam measurement values ​​that satisfy the event conditions in the measurement report MAC CE. Furthermore, the UE100 can also, for example, filter beam measurement values ​​by event type. Specifically, the UE100 selects the beam measurement values ​​to report according to the event type, for example, as follows. - Events LTM1, LTM2 (serving cell beam only): Since these events relate to changes in the state of the serving cell, only the beam measurement information of the serving cell needs to be reported. - Event LTM4 (candidate cell beam only): Since these events relate to changes in the state of the candidate cell, only the beam measurement information of the candidate cell needs to be reported. - Events LTM3, LTM5 (including beams of both serving cell and candidate cell): Since these events relate to changes in the state between the serving cell and the candidate cell, beam measurement information for both is reported. By using the mechanism described above and reporting only the necessary information, the consumption of wireless resources can be reduced and efficient communication can be achieved. Note that the event type is not limited to the above L1 / L2 events, but may also be an L3 (RRC) event.

[0111] (c) Prioritizing beam measurements in order of the duration of event condition satisfaction Here, the predetermined priority is to store beam measurement values ​​in the measurement report MAC CE in order of the duration of event condition satisfaction in the event evaluation. Specifically, for example, beam measurement values ​​may be prioritized as follows: - UE100 may start measuring time for each beam from the time it enters or leaves the event condition, and prioritize the beam measurement values ​​in order from the time the event is triggered, or the time the measurement report MAC CE is generated / reported. - UE100 may record the time it enters or leaves the event, or the time the event is triggered, for each beam, and prioritize the beam measurement values ​​in order from the time the oldest. Note that if a measurement beam enters / leaves the event condition and then leaves / enters again during time measurement, UE100 will reset the measurement time for the measurement beam and restart measurement from the time the measurement beam enters / leaves the event condition again. By prioritizing beam measurements in this way, we can capture stable state changes and detect more appropriate beams by considering the duration of time that the event conditions are met, rather than temporary fluctuations.

[0112] (d) Prioritizing the order of beam identifiers (IDs) Here, the predetermined priority is to store the beam measurement values ​​in the measurement report MAC CE in order of the beam identifier values ​​set by the gNB200, either in descending order or in descending order. Specifically, for example, the beam IDs "1, 2, 3" exist among the measured beams or beams that meet the event conditions. If the gNB200 sets the priority to descending order of beam identifier values, the UE100 stores the beam measurement values ​​in the measurement report MAC CE according to the priority of the beam IDs "3, 2, 1". On the other hand, if the gNB200 sets the priority to descending order of beam identifier values, the UE100 stores the beam measurement values ​​in the measurement report MAC CE according to the priority of the beam IDs "1, 2, 3". The gNB200 may, for example, control the priority by assigning beam IDs in descending order or in descending order starting with the beams that it wants to prioritize.

[0113] Furthermore, the predetermined priority order may be, for example, a priority order in which beam measurement values ​​are stored in the measurement report MAC CE in order of priority of beam identifier type. For example, if two types of beams, SSB beams and CSI-RS beams, are mixed in one measurement report MAC CE, the priority order is set as follows: ・CSI-RS beam priority: The CSI-RS beam with a narrower bandwidth is given priority. This is set, for example, when prioritizing a beam that has the specific characteristics of UE100. ・SSB beam priority: If they are the same RSRP, the SSB beam with a wider bandwidth is more stable than the CSI-RS beam with a narrower bandwidth, so the SSB beam is given priority. Note that UE100 may set whether to prioritize the CSI-RS beam or the SSB beam. gNB200 may set it and notify UE100.

[0114] (e) Prioritizing beams in order of the most recent time when the event condition is met. Here, the predetermined priority is the priority given to storing beam measurement values ​​in the measurement report MAC CE in order of the most recent time when the event condition is met during event evaluation. When a beam that meets the event condition at the most recent time (the latest beam) is detected, the highest priority is assigned to that latest beam, the beam that previously had the highest priority is changed to the second priority, and the priority of past beams is similarly lowered. For example, if the event condition is that TTT is met, assigning the highest priority to a new beam that meets the event condition as described above allows the beam that triggered the event condition in the current channel state to be extracted with the highest priority, thereby improving the reliability of the beam measurement values.

[0115] UE100 may set which of the above priorities (a) to (e) to apply, or any combination thereof. gNB200 may set the priorities and include the prioritization information in the LTM settings and notify UE100. Alternatively, gNB200 does not need to set priorities for storing beam measurement values ​​in the measurement report MAC CE. In this case, UE100 may store beam measurement values ​​in the measurement report MAC CE according to a predetermined priority, for example, any of the predetermined priorities (a) to (e) above, or any combination thereof.

[0116] As described above, when an event condition is met, UE100 stores beam measurement values ​​from among multiple beam measurement values ​​into the measurement report MAC CE according to a predetermined priority order. This operation allows UE100 to store the optimal beam measurement values ​​for reporting into the measurement report MAC CE and report them to gNB200, thereby improving LTM.

[0117] (4.1) Example of operation of UE100 1 Based on the above-described configuration and operation, an example of operation of UE100 according to the embodiment will be described. Figure 11 is a diagram showing an overview of the example of operation of UE100 according to the embodiment.

[0118] First, the receiving unit 110 of UE100 receives the LTM settings from gNB200 (step S101). Here, the LTM settings include the L1 measurement report settings. The L1 report measurement settings include setting information such as event condition settings, measurement target settings, and measurement report settings. The LTM settings are transmitted to UE100 from gNB200, for example, by an RRC Reconfiguration message.

[0119] The event condition setting includes, for example, at least one of the following settings: • Event Type: Information that is one of Event LTM1 to Event LTM5 - Event LTM1: The serving cell's beam is better than the absolute threshold; - Event LTM2: The serving cell's beam is worse than the absolute threshold; - Event LTM3: The LTM candidate cell's beam is better than the serving cell's beam by a certain offset; - Event LTM4: The LTM candidate cell's beam is better than the absolute threshold; - Event LTM5: The serving cell's beam is worse than absolute threshold 1, AND the LTM candidate cell's beam is better than another absolute threshold 2. • Offset Value: Used to adjust the priority of a particular cell; cells with larger offset values ​​are more likely to be selected. • TTT Value • Report on Leave Required: Setting whether or not to report to gNB200 when UE100 leaves a cell.

[0120] The measurement target settings include, for example, at least one of the following setting values: • Candidate cell ID: LTM candidate ID or candidate cell setting ID • Type of beam to be measured for the candidate cell: SSB or CSI-RS • Beam ID: SSBRI, CRI, TCI state ID, etc.

[0121] The measurement reporting settings include, for example, at least one of the following settings: • Maximum number of reporting beams • Number of reporting beams that the measurement reporting MAC CE can accommodate

[0122] Furthermore, the LTM settings may include identification information for the measurement settings, such as a measurement ID, for linking with the L1 measurement report settings described above.

[0123] Next, the control unit 130 of the UE 100 performs beam measurement according to the received LTM settings (step S102). The beam measurement measures, for example, the RSRP and / or SINR of the reference signal detected from the beam.

[0124] Next, the control unit 130 of the UE100 performs an event evaluation using the beam measurement values ​​(step S103). There are two types of event conditions: entering conditions and leaving conditions. Below, we will explain each operation using the entering condition as an example, but each operation can also be applied to the leaving condition.

[0125] Next, the control unit 130 of the UE 100 detects a beam that has entered the event conditions during the event evaluation (step S104). In this process, the UE 100 detects at least one beam. If the UE 100 fails to detect a beam that has entered the event after a predetermined time has elapsed, the beam measurement and event evaluation may be repeated.

[0126] Next, the control unit 130 of the UE 100 determines whether the entering state of each detected beam has continued for a certain period of time (TTT) (step S105).

[0127] In the process of step S105, if the control unit 130 of UE100 determines that the beam entering state has not continued for a certain period of time (TTT) (in the case of a NO determination in step S105), it repeatedly executes the process of step S105.

[0128] On the other hand, in the process of step S105, if the control unit 130 of UE100 determines that the beam entering state has continued for a certain period of time (TTT) (in the case of a YES determination in step S105), it triggers the transmission of the measurement report MAC CE (step S106).

[0129] Next, the control unit 130 of UE100 starts generating the measurement report MAC CE (step S107).

[0130] Next, the control unit 130 of the UE 100 determines whether all beam measurement values ​​can be stored in the measurement report MAC CE (step S108). In this process, the control unit 130 of the UE 100 determines whether all held beam measurement values ​​can be stored in the measurement report MAC CE based on the maximum number of reported beams (N) included in the LTM settings received from the gNB, or the number of reported beams (M) of the measurement report MAC CE.

[0131] In the process of step S108, if the control unit 130 of UE100 determines that all beam measurement values ​​can be stored in the measurement report MAC CE (in the case of a YES determination in step S108), it stores all beam measurement values ​​in the measurement report MAC CE and executes the process of step S111 described below.

[0132] On the other hand, in the process of step S108, if the control unit 130 of UE100 determines that it is not possible to store all beam measurement values ​​in the measurement report MAC CE (in the case of a NO determination in step S108), it selects beam measurement values ​​to be stored in the measurement report MAC CE according to a predetermined priority order (step S109).

[0133] Next, the control unit 130 of UE100 stores the beam measurement values ​​selected according to a predetermined priority order into the measurement report MAC CE (step S110). The processes described in steps S104 to S110 above are referred to as "prioritization processing".

[0134] If the NO determination is made in step S108, or after the processing in step S110, the transmission unit 120 of UE100 transmits the measurement report MAC CE to gNB200 (step S111). In this process, the transmission unit 120 of UE100 performs a transmission process to send the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to gNB200.

[0135] In the above description, the series of operations of UE100 related to LTM measurement and measurement result reporting were explained using the entering condition as an example, but this disclosure is not limited thereto. For example, if Report on Leave is set to "Required" in the event condition setting, the processing of each of the above steps may correspond to the leaving condition. Also, the above example of UE100 operation 1 can be applied to truncated measurement reporting MAC CE.

[0136] (4.2) Example of operation of UE100 2 In Example of operation of UE100 described above, if not all beam measurement values ​​can be stored in the measurement report MAC CE, UE100 stores some beam measurement values ​​in the measurement report MAC CE according to a predetermined priority and reports them to gNB200. Therefore, the challenge is how to handle the remaining unreported beam measurement values. In view of this challenge, in Example of operation 2 described below, the UE100 according to the embodiment stores the unreported beam measurement values ​​in the measurement report MAC CE to be sent as a continuation of the previously sent measurement report MAC CE according to a predetermined priority, depending on whether the predetermined reset conditions are not met, and sends it to gNB200. Hereinafter, the measurement report MAC CE sent as a continuation of the previously sent measurement report MAC CE will be referred to as the "Subsequent measurement report MAC CE".

[0137] Figures 12 and 13 show an overview of Operation Example 2 of UE100 according to the embodiment. In Operation Example 2 of UE100, as shown in Figures 12 and 13, the processing of each step other than steps S201, S210, and S212 to S214 is the same as the processing of these steps in Operation Example 1 of UE100 shown in Figure 11. In the following description, explanations that overlap with the processing of each step that is the same as in Operation Example 1 of UE100 will be omitted, and only steps S201, S210, and S212 to S214 will be described.

[0138] In step S201 shown in Figure 12, UE100 receives LTM settings from gNB200 (step S201). In this process, the LTM settings include the L1 measurement report settings described in step S101 of Operation Example 1, and further include information regarding predetermined reset conditions. Here, the predetermined reset conditions are information for determining whether or not to reset the measurement report MAC CE to its initial transmission state, and include, for example, at least one of the following conditions: Each condition: - No unreported beam measurement values ​​exist - The maximum number of reportable beams (N) has been reached - A certain period of time has elapsed since the last measurement report MAC CE transmission - New beam measurement values ​​have been acquired (the next measurement has been performed) - Transmission of Subsequent measurement report MAC CE is not set

[0139] Note that the initial transmission state of the measurement report MAC CE is not a continuation of the previously transmitted measurement report MAC CE, but rather the initial transmission state corresponding to a new L1 measurement report. In addition, UE100 may receive information from gNB200 specifying some or all of the conditions included in the predetermined reset conditions.

[0140] The above conditions may also be conditions for sending a Subsequent measurement report MAC CE, rather than reset conditions. In this case, the conditions for sending a Subsequent measurement report MAC CE may include at least one of the following conditions: Each condition: - There are unreported beam measurements - The maximum number of reported beams (N) has not been reached - A certain period of time has not elapsed since the last measurement report MAC CE was sent - No new beam measurements have been acquired (the next measurement has not been performed) - Sending a Subsequent measurement report MAC CE is set

[0141] After the processing in step S201, UE100 executes the processing in steps S102 to S109, similar to the operation example 1.

[0142] After processing in step S109, UE100 executes the process in step S210. In the process of step S210, UE100 stores the selected beam measurement values ​​in the measurement report MAC CE and stores information regarding the number of beam measurement values ​​stored. Here, the information regarding the number of beam measurement values ​​stored in the measurement report MAC CE is, for example, the number of beam measurement values ​​stored in the measurement report MAC CE among all beam measurement values ​​held by UE100. Alternatively, the information regarding the number of beam measurement values ​​stored in the measurement report MAC CE may be, for example, the index of the last beam measurement value stored in the measurement report MAC CE, and / or the index of the beam measurement value following the last stored beam measurement value. In addition, in this process, UE100 may store the held beam measurement values ​​or unreported beam measurement values ​​in association with a predetermined priority order.

[0143] After processing in step S210, UE100 performs the processing in step S111, similar to operation example 1, and sends the measurement report MAC CE to gNB200.

[0144] Next, UE100 determines whether a predetermined reset condition has been met (step S212). In this process, if UE100 determines that the predetermined reset condition has been met (in the case of a YES determination in step S212), it terminates the current L1 measurement report and starts receiving the next UL grant.

[0145] On the other hand, in the process of step S212, if UE100 determines that the predetermined reset condition is not met (in the case of a NO determination in step S212), it executes the Subsequent measurement report MAC CE transmission process, that is, the processes of steps S213 and S214 described later. Here, when the predetermined reset condition is set as the transmission condition for the Subsequent measurement report MAC CE, the meaning of each condition and the IF statement (conditional statement) are reversed. Specifically, if UE100 determines that the transmission condition for the Subsequent measurement report MAC CE is met (in the case of a YES determination), it executes the Subsequent measurement report MAC CE transmission process (steps S213 and S214 described later). On the other hand, if UE100 determines that the conditions for sending the Subsequent measurement report MAC CE are not met (i.e., a NO determination is made), it terminates the current LTM measurement report and begins receiving the next UL grant.

[0146] If the determination in step S212 is NO, UE100 stores the unreported beam measurement values ​​in the Subsequent measurement report MAC CE according to a predetermined priority order (step S213).

[0147] Next, UE100 sends the Subsequent measurement report MAC CE to gNB200 (step S214). After processing in step S214, UE100 returns to and executes the processing in step S212.

[0148] As described above, in the operation example 2 of the embodiment of UE100, UE100 stores unreported beam measurement values ​​in the Subsequent measurement report MAC CE according to a predetermined priority order and transmits them to gNB200, depending on whether a predetermined reset condition is not met. This operation of UE100 allows all beam measurement values ​​to be reported to gNB200, widening the selection range of candidate beams and enabling the selection of beams with better wireless quality, thereby improving LTM. Furthermore, the operation example 2 of UE100 described above can also be applied to the truncated measurement report MAC CE.

[0149] (5) Example of Measurement Report MAC CE Configuration In 3GPP Release 19, it is being considered to include the following various types of information as basic information in the Measurement Report MAC CE: ・ Beam information: SSBRI / CRI, or LTM setting identification information + SSBRI / CRI ・ Beam radio quality information: L1-RSRP, or L1-SINR for each beam ・ L1 LTM measurement event information: L1 LTM measurement event identification information, or measurement report setting identification information (ReportConfigID) ・ Maximum number of reportable beams (N) of the Measurement Report MAC CE: The maximum number of reportable beams (N) is set by gNB200

[0150] Additionally, as optional information, the measurement report MAC CE may include information regarding the currently serving beam of UE100 and information regarding the radio quality of the beam. It has also been considered that whether or not the measurement report MAC CE includes this optional information may be determined by gNB200.

[0151] Furthermore, 3GPP Release 19 is considering using SSBRI and CRI as beam identification information in the measurement report MAC CE, and setting the maximum number of reported beams (N) in event-triggered L1 LTM measurement reports to be the number of beams that can be stored in the measurement report MAC CE. In addition, 3GPP Release 19 is considering allowing the network to control (set) whether or not to report beam measurement values ​​that do not meet the event conditions, including two types of beam measurement values, SSB and CSI-RS, in a single measurement report MAC CE, and supporting truncated measurement report MAC CEs.

[0152] Furthermore, since the maximum number of beams (N) to be reported in the measurement report MAC CE can be set by the gNB200, it can be assumed that the format of the measurement report MAC CE is variable length. Therefore, if the number of beams measured is smaller than the set maximum number of beams (N), the efficiency of wireless resource utilization can be improved by reducing the size of the measurement report MAC CE. Thus, the challenge becomes how to reduce the size of the measurement report MAC CE.

[0153] (5.1) Example Configuration of Measurement Report MAC CE 1 In view of the above issues, the format of the measurement report MAC CE according to the embodiment is configured as shown in Figure 14. Figure 14 is Example Configuration 1 of the format of the measurement report MAC CE according to the embodiment. Here, it is assumed that the LTM settings transmitted from gNB200 to UE100 include Beam ID (beam identification information: 4 bits), Triggered event info. (identification information of measurement report settings such as ReportConfigID: 6 bits), N (maximum number of reported beams: 4 bits), and Current beam report setting (current serving beam report: True / False).

[0154] As shown in Figure 14, the variable-length measurement report MAC CE includes Common field, Variable field, and Optional field.

[0155] The Common field includes a 2-bit reserved (R) area and a 6-bit triggered event info area. The triggered event info area stores identification information for the triggered L1 LTM measurement event, such as the ReportConfigID.

[0156] The Variable field includes a 1-bit SSBRI / CRI area, a 4-bit Beam ID area, and a 7-bit L1-RSRP or L1-SINR area for each beam. Figure 14 shows an example where four beams are stored in the Variable field. The SSBRI / CRI area stores identification information indicating whether the stored beam measurement value is an SSB measurement value or a CSI-RS measurement value. The Beam ID area stores identification information of the stored beam measurement value, such as SSBRI, CRI, etc. The L1-RSRP or L1-SINR area stores the beam measurement value corresponding to the Beam ID, i.e., the L1 measurement result (L1-RSRP, L1-SINR, etc.).

[0157] The Optional field has the same region as the Variable field. The SSBRI / CRI region of the Optional field stores identification information indicating whether the beam measurement value of the UE100's current serving beam is an SSB measurement value or a CSI-RS measurement value. The Beam ID region of the Optional field stores identification information of the beam measurement value of the UE100's current serving beam, such as SSBRI, CRI, etc. The L1-RSRP or L1-SINR region stores the beam measurement value of the UE100's current serving beam (L1-RSRP, L1-SINR, etc.). Furthermore, if the Current beam report in the LTM settings sent from gNB200 to UE100 is "False", the measurement report MAC CE will not include the Optional field.

[0158] Here, the SSBRI / CRI region in the Variable field and Optional field is newly provided, and UE100 stores identification information in this region indicating whether the type of beam measurement value stored in the measurement report MAC CE is an SSB measurement value or a CSI-RS measurement value. The information stored in the SSBRI / CRI region is, for example, flag information, where if "1" is stored, it indicates that the type of beam measurement value is SSB, and if "0" is stored, it indicates that the type of beam measurement value is CSI-RS.

[0159] Furthermore, the SSBRI / CRI information in the format of the measurement report MAC CE described above may be unnecessary in some cases. For example, if UE100 stores only beam measurement values ​​of the same type in the measurement report MAC CE, the identification information of the beam measurement value type (SSBRI / CRI area) may be omitted. Specifically, for example, UE100 stores only beam measurement values ​​of the same type as the beam measurement value that triggered the generation of the measurement report MAC CE in accordance with the LTM setting from gNB200, and does not store beam measurement values ​​of different types. This operation eliminates the need for beam measurement value type information in the measurement report MAC CE, thereby improving the efficiency of wireless resource utilization. The following describes an example of the operation of the mobile communication system 1 in this case.

[0160] Figure 15 shows an example of the operation of the mobile communication system 1 according to the embodiment. The example of operation shown in Figure 15 is performed, for example, between step S6 (synchronization processing with LTM candidate cells) and step S8 (LTM cell switching decision) of the example of the cell switching procedure by LTM in the intraCU shown in Figure 7. Also, the processing of steps S102 to S107 shown in Figure 15 is the same as the processing of each step shown in Figure 11, so redundant explanations are omitted.

[0161] After step S6 (synchronization process with LTM candidate cell) shown in Figure 7, UE100 executes steps S102 to S107 shown in Figure 15. Subsequently, UE100 stores the beam measurement values ​​that triggered the generation of the measurement report MAC CE into the measurement report MAC CE (step S701). Here, an example has been described in which the operation example shown in Figure 15 starts after the process of step S6 shown in Figure 7, but the operation example shown in Figure 15 may start before the process of step S6 shown in Figure 7. The operation example shown in Figure 15 may also start after the process of step S5 (sending of RRC Reconfiguration Complete message).

[0162] Next, UE 100 selects only beam measurement values ​​of the same type as the beam measurement value that triggered the generation of the measurement report MAC CE and stores them in the measurement report MAC CE (step S702). In this process, as explained in Figure 11, UE 100 may store only beam measurement values ​​of the same type as the beam measurement value that triggered the generation of the measurement report MAC CE in the measurement report MAC CE according to a predetermined priority order.

[0163] Next, UE100 sends a measurement report MAC CE (i.e., L1 Measurement Report) to gNB (step S703). In this process, UE100 may also send a Subsequent measurement report MAC CE depending on whether the predetermined reset conditions are not met, as described in Figures 12 and 13.

[0164] Next, the gNB200 identifies the type of beam measurement value associated with the event ID (e.g., ReportConfigID) stored in the Triggered event info. area of ​​the measurement report MAC CE from the LTM settings (step S801). Note that when the gNB200 performs LTM settings, it sets the information on the type of beam measurement value by associating it with the identification information of the LTM measurement event or the identification information of the measurement report settings (e.g., ReportConfigID).

[0165] Next, the gNB200 associates the beam ID in the measurement report MAC CE with the type of beam measurement value identified and reads each beam measurement value (step S802).

[0166] After the processing in step S802, the gNB200 uses the beam measurement values ​​in the MAC CE measurement report and the identified beam measurement values ​​to perform the processing in step S8 (LTM cell switching determination) shown in Figure 7.

[0167] On the other hand, 3GPP Release 19 considers determining the type of measurement beam for serving cells by setting the type of measurement beam for LTM candidate cells. However, if the event condition for LTM measurement is set to event LTM2 (the serving cell beam deteriorates below the absolute threshold), the event condition only relates to the serving cell beam, and it becomes impossible to set the type of measurement beam for serving cells by setting the type of measurement beam for LTM candidate cells.

[0168] In light of the above situation, the UE 100 according to the embodiment stores a beam measurement value of the same type as the current serving beam type in the measurement report MAC CE when the event condition for LTM measurement is a condition in which the serving cell beam deteriorates below an absolute threshold (event LTM2). This operation eliminates the need to set the beam type and also eliminates the need for beam measurement value type information in the measurement report MAC CE, thereby improving the utilization efficiency of wireless resources.

[0169] Alternatively, instead of the SSBRI / CRI area in the measurement report MAC CE shown in Figure 14, a 1-bit area for storing identification information of the type of L1 measurement result may be provided. In this case, UE 100 stores, for example, identification information indicating whether the type of L1 measurement result of the beam measurement value stored in the measurement report MAC CE is L1-RSRP or L1-SINR in that area of ​​the measurement report MAC CE. Similar to the beam type identification information described above, there are cases where the identification information of the type of L1 measurement result is unnecessary. For example, if UE 100 stores only beam measurement values ​​in the measurement report MAC CE that have the same type of L1 measurement result, the identification information of the type of L1 measurement result may not be necessary. Specifically, for example, UE100 stores only beam measurement values ​​that have the same type of L1 measurement result as the beam measurement value that triggered the generation of the measurement report MAC CE, in accordance with the LTM setting from gNB200, and does not store beam measurement values ​​that have a different type of L1 measurement result. This operation allows for the selection of a more appropriate target cell (target beam). Note that the operation of the mobile communication system 1 in this case is the same as the operation when "type of beam measurement value" is replaced with "type of L1 measurement result" in the operation example described in Figure 15, so a detailed explanation is omitted here.

[0170] (5.2) Example of MAC CE Configuration 2 When UE100 reports beam measurement values ​​from multiple candidate cells, it assigns candidate cell identification information (LTM candidate ID or MeasID) to each beam measurement value. When multiple beam measurement values ​​exist from the same candidate cell, there is a problem that the size of the MAC CE measurement report increases due to the repeated assignment of the same candidate cell identification information.

[0171] Therefore, the configuration example 2 of the measurement report MAC CE according to the embodiment includes flag information for each beam measurement value indicating whether or not it is the same candidate cell as the previous beam measurement value. When UE 100 stores multiple beam measurement values ​​in the measurement report MAC CE, it stores in the measurement report MAC CE information indicating whether or not each beam measurement value stored in the measurement report MAC CE is a beam measurement value for the same cell as the previous beam measurement value.

[0172] Figure 16 shows an example configuration 2 of the measurement reporting MAC CE according to the embodiment. As shown in Figure 16, the measurement reporting MAC CE includes a Common field, a Variable field, and an Optional field. The Common field is the same as the Common field in the measurement reporting MAC CE configuration example 1 described in Figure 14, so its explanation is omitted.

[0173] The Variable field includes, for each beam, a 3-bit LTM candidate ID area, a 1-bit SSBRI / CRI area, a 4-bit Beam ID area, a 7-bit L1-RSRP or L1-SINR area, and a 1-bit Cont area. Figure 16 shows an example where five beams from four candidate cells are stored. The SSBRI / CRI area, Beam ID area, and L1-RSRP or L1-SINR area are the same as those described in Figure 14, so their explanation is omitted.

[0174] The LTM candidate ID area stores identification information for the cell to which the stored beam measurement value belongs. The Cont area stores information, such as flag information, indicating whether the stored beam measurement value is for the same cell as the previous beam measurement value. For example, if the flag information is "1", it indicates that the beam measurement value is for the same cell as the previous beam measurement value, and if it is "0", it indicates that the beam measurement value is not for a different cell than the previous beam measurement value. The UE100 prevents each beam measurement value from having an LTM candidate ID area depending on whether it is a beam measurement value for the same cell as the previous beam measurement value (the value in the Cont area is "1"). For example, the second and fifth beam measurement values ​​in the Variable field shown in Figure 16 do not have an LTM candidate ID stored because the corresponding Cont area value is "1". This operation reduces the size of the measurement report MAC CE by avoiding the duplication of identification information for the same candidate cell into the measurement report MAC CE, thereby improving the efficiency of wireless resource utilization.

[0175] (5.3) Example of MAC CE Configuration 3 When UE100 reports beam measurement values ​​from multiple candidate cells together, a Ci field as shown in Figure 17 may be provided as a method for compressing the identifier information of the multiple candidate cells. Figure 17 is a diagram showing an example of MAC CE configuration 3 according to the embodiment.

[0176] Configuration Example 3 of the Measurement Report MAC CE has the same regions as Configuration Example 1 of the Measurement Report MAC CE shown in Figure 14, and eight 1-bit Ci fields are provided at the beginning of the Variable field. The "i" in the Ci field corresponds to "0" to "7", which are identification information for LTM candidate cells. The Ci field stores information indicating whether or not the beam measurement value for the candidate cell corresponding to "i" is included, for example, flag information. For example, if the flag information is "1", it indicates that the beam measurement value for the candidate cell is included, and if it is "0", it indicates that the beam measurement value for the candidate cell is not included. Also, if information indicating that the beam measurement value for a candidate cell is included (for example, flag "1") is stored in the Ci field, one beam measurement value for the candidate cell corresponding to that Ci is stored in the Variable field.

[0177] By using the configuration of the measurement report MAC CE shown in Figure 17, only one beam measurement value can be reported for each candidate cell. Therefore, when UE 100 stores the beam measurement values ​​of multiple cells in the measurement report MAC CE, it stores the highest beam measurement value for each of the multiple cells in the measurement report MAC CE. This operation reduces the size of the measurement report MAC CE by compressing the identifier information of multiple candidate cells, thereby improving the efficiency of wireless resource utilization.

[0178] (5.4) Example of Measurement Report MAC CE Configuration Example 4 of the Measurement Report MAC CE is an example of a Measurement Report MAC CE configuration with the minimum number of bits to further reduce the size of the Measurement Report MAC CE. Figure 18 is a diagram showing the Measurement Report MAC CE Configuration Example 4 according to the embodiment.

[0179] As shown in Figure 18, Configuration Example 4 of the Measurement Report MAC CE has a Common field and a Fixed field. The Common field is the same as the Common field in each of the above-described Configuration Examples. The Fixed field stores only one beam measurement value. In Configuration Examples 1 to 3 of the Measurement Report MAC CE described above, the Optional field stores the beam measurement information of the current serving (including the type of beam measurement value, beam identification information, beam measurement value, etc.). This information is not necessary for selecting a target cell (beam), so it can be saved. For this reason, Configuration Example 4 of the Measurement Report MAC CE does not include an Optional field. When UE100 transmits a measurement report MAC CE with the minimum number of bits, it controls the UE100 not to store the beam measurement information of the current serving beam in the measurement report MAC CE, even if gNB200 has configured it to do so. Similarly, when UE100 transmits a normal truncated measurement report MAC CE, it may also control the UE100 not to store the beam measurement information of the current serving beam in the truncated measurement report MAC CE, even if gNB200 has configured it to do so. This operation reduces the size of the measurement report MAC CE to the minimum number of bits, further improving the efficiency of wireless resource utilization.

[0180] (5.5) Example Configuration 5 of the Measurement Report MAC CE Figure 19 shows an example configuration 5 of the Measurement Report MAC CE according to the embodiment. As shown in Figure 19, Example Configuration 5 of the Measurement Report MAC CE has a Common field and a Variable field, but does not have an Optional field. The Common field is the same as the Common field in each of the above-described configuration examples. The Variable field has each of the configuration regions of the Variable field in Example Configuration 2 of the Measurement Report MAC CE shown in Figure 16, and further has a 4-bit Length region.

[0181] The Length region is located at the beginning of the Variable field and stores information indicating the number of beam measurement values ​​to be stored in the measurement report MAC CE. By providing the Length region in the measurement report MAC CE, the gNB200 can determine the number of beam measurement values ​​to be reported. In particular, when a Subsequent measurement report MAC CE is transmitted, the gNB200 can determine the number of unreported beam measurement values ​​by knowing the number of beam measurement values ​​to be reported from the beginning, and can receive all measurement reports without omission.

[0182] Furthermore, the above-mentioned MAC CE measurement report configuration examples can be implemented not only individually but also in combination of two or more. Additionally, when combining the above-mentioned MAC CE measurement report configuration examples, some of the configurations may be modified.

[0183] Furthermore, the above-mentioned configuration examples for measurement reporting MAC CE can also be applied to truncated measurement reporting MAC CE.

[0184] (6) Other Embodiments In the embodiments described above, in the L1 event evaluation, cell-level measurement results may be used in addition to beam-level measurement results. Cell-level L1 measurement results are more stable than beam-level measurement results. There are two types of cell-level measurements: - Measurement results originating from the beam, but without L3 filtering; - Legacy L3 measurement results, i.e., measurement results after L3 filtering.

[0185] In either case, event evaluation based on measurement results at both the beam level and the cell level is considered to contribute to the stability of the evaluation results. For example, when a beam-level event LTM3 and a cell-level event LTM4 (or event A4) are combined, the LTM decision based on event LTM3 (i.e., cell switching) will only occur after event LTM4 is met (i.e., the quality of this LTM candidate cell is better than a certain level). Therefore, a composite event based on measurements at both the beam level and the cell level can improve the stability of the event evaluation.

[0186] In the embodiments described above, there are three possible options for the layer that performs L1 event evaluation (i.e., evaluation of enter and leave conditions): • L1 (PHY layer): This is a feasible option because conventional L1 measurement reports are performed at the PHY layer. The drawback is that it is expected to have a significant impact on the PHY layer specifications; • L2 (MAC layer): This is a feasible option because LTM determination is performed at the gNB200's DU and cell switching commands are sent as MAC CE. The drawback is a significant impact on the MAC specifications, including several inter-layer interactions. For example, MAC needs to control the start / stop of L1 measurement reporting to PHY; • L3 (RRC layer): Functionality for event-triggered L3 measurement reporting is available at the RRC layer, so it may be reusable with relatively little effort / modification. The drawback is that it requires inter-layer interactions, such as RRC instructing PHY to start / stop L1 measurement reporting.

[0187] Each of these three options has its advantages and disadvantages, and all are technically feasible. However, since the cell switching command is processed at the MAC layer, the MAC layer is the appropriate layer, and the impact of PHY can be minimized.

[0188] In the embodiments described above, there are three possible options for the layer that performs L1 measurement reporting: • L1 (UCI): This is a valid option because there is an existing periodic L1 measurement reporting mechanism. Therefore, from the perspective of the reporting mechanism, it may be necessary to modify the specifications, such as turning periodic L1 measurement reporting on / off when entering / leaving an event state. The drawback is that it may be unclear whether this contributes to a significant improvement in radio resource efficiency; • L2 (MAC CE): This is a reasonable option because subsequent cell switching commands are transmitted by the MAC layer, and the procedure including LTM determination can be handled at the same layer. Furthermore, MAC CE is fast enough for the gNB200 to perform LTM determination. The drawback is that it is assumed that a new MAC CE will need to be specified; • L3 (RRC message): This is a possible option because an L3 measurement reporting framework already exists. However, since LTM is a low-latency cell switching mechanism and the LTM decision is made by the gNB200's DU, RRC messages experience considerable delay on both the radio interface and the network interface (i.e., F1-AP).

[0189] Therefore, from a latency perspective, RRC messages are difficult to apply to LTM, making either UCI or MAC CE a viable option. However, MAC CE is preferable because it has less complexity regarding inter-layer interactions and minimizes the impact of the PHY specification.

[0190] In the embodiments described above, UE100 preferably includes at least one of the following pieces of information in the L1 measurement report: • Beam measurement results (i.e., L1 measurement results, which may be measurement results for multiple beams and multiple cells) • Beam information (i.e., reference signal identifier, e.g., SSB index or CSI-RS index) • Triggered event information (event ID, e.g., information indicating event LTM3).

[0191] The LTM in the above-described embodiment may be read as a conditional LTM. For example, the LTM of the interCU or intraCU described above may be a conditional LTM of the interCU or intraCU. In a conditional LTM, for example, the RRC Reconfiguration message in step S4 of Figure 6 includes information indicating the execution conditions for LTM cell switching (e.g., wireless quality conditions) for each LTM candidate cell. Instead of receiving the cell switching command MAC CE transmitted from the gNB 200, the UE 100 performs LTM cell switching for LTM candidate cells that meet the pre-configured execution conditions (wireless quality conditions). This enables faster LTM cell switching.

[0192] The above-described operation flows can be performed not only independently, but also in combination of two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. It is not necessary to execute all steps in each flow; only some steps may be executed. Furthermore, the order of steps in each flow may be changed as appropriate.

[0193] In the embodiments and examples described above, an example in which the base station is an NR base station (gNB) was described, but the base station may also be an LTE base station (eNB) or a 6G base station. Furthermore, the base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU of an IAB node. Furthermore, UE100 may be an MT (Mobile Termination) of an IAB node. That is, UE100 may be a terminal function unit (a type of communication module) for the base station to control a relay device that performs signal relay. Such a terminal function unit is referred to as an MT. Examples of multi-transmission architectures (MTs) include IAB-MT, NCR (Network Controlled Repeater)-MT, and RIS (Reconfigurable Intelligent Surface)-MT.

[0194] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU). Additionally, a network node may consist of a combination of at least a part of the core network device and at least a part of a base station.

[0195] A program may be provided that causes a computer to execute each process performed by the UE100 or gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM and / or DVD-ROM. Alternatively, the circuits that execute each process performed by the UE100 or gNB200 may be integrated, and at least a part of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0196] The functions realized by the above-described communication device (UE100 or gNB200, etc.) may be implemented in a circuit or processing circuit, including a general-purpose processor, application-specific processor, integrated circuit, ASICs (Application Specific Integrated Circuits), CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to realize the described functions. The processor includes transistors and / or other circuits and is considered a circuit or processing circuit. The processor may also be a programmed processor that executes a program stored in memory. In this specification, circuit, unit, and means are hardware programmed to perform or execute the functions described herein. Such hardware may be any hardware disclosed herein, or any hardware known to be programmed to perform or execute the functions described herein. If such hardware is a processor that is considered to be of the type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0197] The phrases “based on” and “depending on / in response to” as used in this disclosure do not mean “based solely on” or “in response solely” unless otherwise specified. “Based on” means both “based solely on” and “at least partially on.” Similarly, “depending” means both “at least partially on” and “at least partially on.” The terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included, but that they may include only the listed items or may include additional items in addition to the listed items. Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR. Moreover, any reference to elements using designations such as “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0198] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention.

[0199] This application claims priority to U.S. Provisional Application No. 63 / 754119 (filed February 5, 2025), the entirety of which is incorporated into the specification of this application.

[0200] (7) First Supplementary Notes The features of the above-described embodiment are described below.

[0201] - Appendix 1 A communication method performed by a user device in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), comprising: performing an event evaluation to determine whether an event condition has been met for transmitting a measurement report MAC (Medium Access Control) CE (Control Element) containing beam measurement values ​​obtained by radio quality measurement of a beam to a network node; performing a prioritization process to select beam measurement values ​​from a plurality of beam measurement values ​​obtained by the radio quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order, in response to the event condition being met; and performing a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to the network node.

[0202] - Appendix 2 The communication method described in Appendix 1, wherein the measurement report MAC CE is a truncated measurement report MAC CE that can be placed in the available area of ​​the MAC PDU (Protocol Data Unit).

[0203] - Appendix 3 The communication method described in Appendix 1 or 2, wherein the predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in descending order of value.

[0204] - Appendix 4 The communication method described in Appendix 1 or 2, wherein the predetermined priority is to prioritize storing beam measurement values ​​that satisfy the event conditions in the event evaluation into the measurement report MAC CE.

[0205] - Appendix 5 The communication method described in any of Appendix 1 to 4, wherein the predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in order of the longest duration of the event conditions being met in the event evaluation.

[0206] - Appendix 6 The communication method described in any of Appendix 1 to 5, wherein the predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in descending order of the beam identifier values ​​set by the network node.

[0207] - Appendix 7 The communication method described in any of the appendices 1 to 6, wherein the predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in the order of the most recent time when the event conditions were met in the event evaluation.

[0208] - Appendix 8 The communication method described in any of Appendix 1 to 7, wherein the user device, in response to the fact that a predetermined reset condition has not been met, transmits unreported beam measurement values ​​to the network node in accordance with the priority order, and stores them in the measurement report MAC CE that is transmitted as a continuation of the previously transmitted measurement report MAC CE.

[0209] - Appendix 9 The predetermined reset conditions are information for determining whether or not to reset the measurement report MAC CE to its initial transmission state, and the predetermined reset conditions include at least one of the following: there are no unreported beam measurement values ​​to the network node; the maximum number of reportable beams set by the network node has been reached; a certain period of time has elapsed since the previous transmission of the measurement report MAC CE; new beam measurement values ​​have been acquired; and the network node has not set to continue transmitting the measurement report MAC CE, as described in Appendix 8 of the communication method.

[0210] - Appendix 10 The communication method described in Appendix 9, wherein the user device receives information from the network node specifying some or all of the conditions included in the predetermined reset conditions.

[0211] - Appendix 11 The communication method according to Appendix 1 or 2, wherein the user device stores identification information in the measurement report MAC CE indicating whether the type of beam measurement value stored in the measurement report MAC CE is an SSB (Synchronization Signal Block) measurement value or a CSI-RS (Channel State Information - Reference Signal) measurement value.

[0212] - Appendix 12 The communication method described in any of Appendix 1, 2, or 11, wherein the user device stores the beam measurement values ​​of the same type in the measurement report MAC CE.

[0213] - Appendix 13 The communication method described in any of Appendix 1, 2, 11 to 12, wherein the user device stores identification information in the measurement report MAC CE indicating whether the type of L1 measurement result of the beam measurement value stored in the measurement report MAC CE is L1-RSRP (Reference Signal Received Power) or L1-SINR (Signal to Interference plus Noise Ratio).

[0214] - Appendix 14 The communication method described in any of Appendix 1, 2, 11 to 13, wherein the user device stores the beam measurement values ​​of the same type as the L1 measurement results in the measurement report MAC CE.

[0215] - Appendix 15 The communication method described in any of Appendix 1, 2, 11 to 14, wherein the user device stores the beam measurement values ​​of the same type of beam as the currently serving beam in the measurement report MAC CE when the event condition is a condition in which the serving cell beam deteriorates below an absolute threshold.

[0216] - Appendix 16 The communication method according to any one of Appendix 1, 2, 11 to 15, wherein when the user device stores a plurality of beam measurement values ​​in the measurement report MAC CE, information indicating whether each stored beam measurement value is a beam measurement value for the same cell as the previous beam measurement value is stored in the measurement report MAC CE.

[0217] - Appendix 17 When the user device stores the beam measurement values ​​of each of the multiple cells in the measurement report MAC CE, the communication method described in any of the appendices 1, 2, 11 to 16 stores the highest beam measurement value for each of the multiple cells in the measurement report MAC CE.

[0218] - Appendix 18 A communication method according to any of the appendices 1, 2, 11 to 17, which controls the user device so that it does not store the beam measurement information of the current serving beam in the measurement report MAC CE, even if the network node has configured the user device to store the beam measurement information of the current serving beam in the measurement report MAC CE.

[0219] - Appendix 19 A user device used in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), comprising: a control unit that performs an event evaluation to determine whether or not an event condition has been met for transmitting a measurement report MAC (Medium Access Control) CE (Control Element) containing beam measurement values ​​obtained by radio quality measurement of a beam to a network node, and performs a prioritization process to select beam measurement values ​​from a plurality of beam measurement values ​​obtained by the radio quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order; and a transmission unit that performs a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to the network node.

[0220] (8) Second Addendum 1. Introduction In RAN#102, a work item relating to NR Mobility Expansion Phase 4 was approved. This included the objective of defining event-triggered L1 measurement reporting. In RAN2#128, the details of this topic were discussed and the following agreements were reached.

[0221] Agreements regarding L1 Event-Driven Measurement Reporting (MR): "1. The Time To Trigger (TTT) is evaluated per beam, and the measurement report is triggered only by beams that meet the conditions (entry / exit) for the entire duration of the TTT." "2. If the current beam is changed and the entry conditions are still met with the new current beam, the TTT timer is not restarted." "3. The TTT applies to the exit conditions." "4. The network can configure which RS type (SSB or CSI-RS) to use for LTM event evaluation." "5. Either CSI-RS or SSB can be configured as a candidate beam, and the measurement RS of the serving cell beam is determined based on the candidate beam to ensure the same RS type. That is, in accordance with the agreement in RAN1, the RS for the current beam of the serving cell is the QCL of the indicated TCI state. "It is either identical to RS or QCL (Quasi-Collocation)." "6. SSBRI and CRI are used to represent candidate beam IDs in LTM MR MAC CE." "7. In event-triggered L1 LTM measurement reports, Max N is the total number of beams included in MR MAC CE." "8. In event-triggered L1 LTM measurement reports, NW controls whether beams that do not satisfy the event can be reported according to N beams in MR MAC CE." "9. A single MAC CE format for event-triggered L1 measurement reports is used for both SSB and CSI-RS reference signals." "10. Supports truncated measurement report MAC CE."

[0222] This addendum discusses the details of event-triggered L1 measurement reporting.

[0223] 2. Discussion 2.1. Cell RAN2 reported in MR MAC CE agreed to support events LTM2, 3, 4, and 5 as follows: During event evaluation, event LTM2 involves only the serving cell, event LTM4 involves only the candidate cell, and events LTM3 and 5 involve both the serving cell and the candidate cell.

[0224] "3. As L1 LTM measurement events, the following LTM events are supported based on the beam-specific quality of the serving cell and candidate cell: • Event LTM2: The serving cell beam falls below the absolute threshold. • Event LTM3: The candidate cell beam is better than the serving cell beam by an offset amount. • Event LTM4: The candidate cell beam is better than the absolute threshold. • Event LTM5: The serving cell beam falls below absolute threshold 1, and the candidate cell beam is better than another absolute threshold 2."

[0225] Regarding the serving beam's measurement RS (i.e., CSI-RS or SSB), RAN2 agreed that it would be implicitly indicated by the candidate beam's measurement RS.

[0226] "5. Either CSI-RS or SSB can be configured as the candidate beam, and the measured RS of the serving cell beam is determined based on the candidate beam to ensure the same RS type. That is, in accordance with the agreement in RAN1, the RS of the serving cell for the current beam is either identical to the QCL RS of the indicated TCI state, or QCL."

[0227] Regarding Event LTM2, it is natural to assume that the current beam (either CSI-RS or SSB) is the measurement target, since the current beam is the most important beam for Event LTM2 (e.g., to constitute the subsequent Event LTM3 / 5), and the candidate cell beam is not involved in the evaluation of Event LTM2.

[0228] Proposal 1: RAN2 should clearly indicate in the configuration of Event LTM2 that the measured RS of the serving cell beam is the current beam corresponding to the object being measured (i.e., it should not have a configuration to indicate whether to use CSI-RS or SSB).

[0229] Regarding the current beam from the serving cell, RAN2 agreed that it is configurable whether the current beam information and quantity are included in MR MAC CE as follows:

[0230] "14. Additional information included in MR MAC CE: • Current beam information and quantity based on the NW configuration."

[0231] Even if the network configured the measurement report triggered by event LTM2 in that way, it is somewhat unusual that the MR MAC CE does not include "current beam information and quantity."

[0232] Proposal 2: RAN2 should clarify that the MR MAC CE triggered by event LTM2 always includes the L1 measurement result of the current beam (i.e., it is not configurable).

[0233] For events LTM3 and LTM5, since both the serving cell beam and the candidate cell beam are involved in the evaluation, it is assumed that the beam quantities from both the serving cell and the candidate cell will be included in the MR MAC CE. On the other hand, it remains unclear whether the MR MAC CE should further include the quantities of other beams from other cells (i.e., adjacent cells that are not candidate cells). Technically, it is possible to report the quantities from adjacent cells if there is sufficient space in the MR MAC CE, but this would incur additional signaling overhead. Therefore, it is somewhat preferable to include only the beam quantities from the serving cell and candidate cell in the MR MAC CE rather than leaving the inclusion of adjacent cell quantities to the network configuration.

[0234] Proposal 3: RAN2 should discuss whether the MR MAC CE triggered by either event LTM3 or event LTM5 includes only the L1 measurement results of beams from the serving cell and candidate cells (i.e., does not include beams from other cells / adjacent cells).

[0235] 2.2. It was agreed that the beam RAN2 reported at MR MAC CE would consist of the total number of beams included in MR MAC CE (i.e., "N"), and whether or not beams that do not meet the event criteria would be reported, as determined by gNB.

[0236] "7. In the event-triggered L1 LTM measurement report, the maximum N is the total number of beams included in the MR MAC CE." "8. In the event-triggered L1 LTM measurement report, NW controls whether or not to report beams that do not satisfy the event, according to the N beams in the MR MAC CE."

[0237] These agreements suggest that even if a UE has L1 measurement results for M beams and M > N, the MR MAC CE will only report with L1 measurement results for N beams. In this case, the UE needs to choose which beams to report and which not to report. The following three options are considered for the UE to determine which beams to report.

[0238] Option 1: The beam that triggered the event has the highest priority in MR MAC CE, beams that satisfy the event have the second highest priority, and the other beams (those that do not satisfy the event) have the lowest priority.

[0239] Option 2: The beams are sorted by L1-RSRP (or L1-SINR) and included in MR MAC CE in this order.

[0240] Option 3: The beams are sorted from the first (and still fulfilling) event to the last, and are included in MR MAC CE in this order.

[0241] Since it is clear that the beams that trigger / satisfy the event are the most useful information for network decisions, option 1 is considered direct.

[0242] Options 2 and 3 may, in some cases, be considered similar to option 1. Generally, option 2 would be beneficial because good beam measurement results are considered in the network. Option 3 may indicate how long each beam has satisfied the event, i.e., how stable each beam is.

[0243] The beam measurement results reported by MR MAC CE are directly related to appropriate decisions made on the network. Therefore, which beams should be included in MR MAC CE should be specified, rather than left to the UE implementation. RAN2 should discuss how the UE should select the beams to be reported.

[0244] Proposal 4: RAN2 should agree to always include the beam that triggered the event in MR MAC CE.

[0245] Proposal 5: RAN2 should discuss how the UE determines which other beams to report (i.e., beams other than the one that triggered the event) (e.g., based on whether they satisfy the event criteria, the order of beam quality, and / or the order of beam stability).

[0246] 2.3. The truncated MR MAC CE RAN2 agreed to the introduction of the truncated MR MAC CE. "10. Support the truncated measurement reporting MAC CE."

[0247] However, the reasons and methods for using the shortened MR MAC CE have not been sufficiently discussed. According to the paper proposing the above agreement, the shortened MR MAC CE is intended for use when the uplink (UL) grant is limited, i.e., when the transport block size (TBS) is not sufficient to carry a "normal" MR MAC CE.

[0248] Proposal 6: RAN2 should ensure that a shortened MR MAC CE is triggered if the "normal" MR MAC CE is not delivered in this UL grant.

[0249] The paper further suggests that "subsequent" shortened MR MAC CEs could report the remaining beam measurement results, making it possible for multiple MR MAC CEs to report all beams. This would be useful, for example, when the network needs more beam measurements for better decisions, but delays in reporting (i.e., waiting for the next UL grant) could cause the measurements to become outdated. RAN2 should discuss whether it is beneficial for multiple MR MAC CEs across different UL grants to report all beam measurement results that a UE has at a given time.

[0250] Proposal 7: RAN2 should discuss whether the “subsequent” shortened MR MAC CE reports the remaining beam that was not reported by the “initial” shortened MR MAC CE.

[0251] According to the current specifications, two types of shortened MAC CEs are defined: shortened BSR and shortened BFR. A shortened BSR is used as a padding BSR when multiple LCGs (Logical Channel Groups) have transmittable data, while a shortened BFR is used when there are no candidate beams in that MAC CE. Considering measurement reports, it may be useful if an MR MAC CE is transmittable within the padding bits (like a padding BSR), but it does not make sense if there are no candidate beams in an MR MAC CE triggered by a particular event (like a shortened BFR). Therefore, RAN2 should discuss whether shortened MR MAC CEs can be transmitted within the padding bits of a MAC PDU.

[0252] Proposal 8: RAN2 should discuss whether a shortened MR MAC CE can be transmitted within the padding bits (like the padding BSR).

[0253] 2.4. MR MAC CE Format RAN2 agreed that beam information and beam quantities for up to N beams could be included in the measurement report MAC CE. It is clear that triggered event information is not related to N beams (i.e., only one piece of information is needed per MAC CE).

[0254] "14. Basic information included in MR MAC CE: • Beam information: Further consideration is needed regarding whether to use SSBRI / CRI or (LTM configuration ID + SSB / CSI-RS ID) for N beams. • Beam quantity: L1-RSRP or SINR (according to RAN1) for N beams. • Triggered event information (e.g., ReportConfigID). MR MAC CE can contain up to N beams (further consideration is needed regarding whether beams should satisfy the event). N can be configured by NW."

[0255] "15. Additional information included in MR MAC CE: • Current beam information and quantity based on the NW configuration."

[0256] RAN2 further agreed that SSBRI and CRI would be used as beam IDs for MR MAC CE, and that a single MAC CE format would be defined for both SSB and CSI-RS.

[0257] "6. In the LTM MR MAC CE, SSBRI and CRI are used to represent candidate beam IDs." "7. In the event-triggered L1 LTM measurement report, Maximum N is the total number of beams included in the MR MAC CE." "8. In the event-triggered L1 LTM measurement report, NW controls whether beams that do not satisfy the event can be reported, according to the N beams in the MR MAC CE." "9. A single MAC CE format for event-triggered L1 measurement reports is used for both the SSB and CSI-RS reference signals."

[0258] Regarding the reporting of "N beams," it is quite natural to assume that the MAC CE should be variable length, since "N" is configurable (and therefore variable), and it is efficient to reduce the MAC CE size when the number of beam measurement results is less than the configured "N". To begin examining the details of the MR MAC CE format, RAN2 should first agree that the MR MAC CE should be variable length.

[0259] Proposal 9: RAN2 should agree that MR MAC CE should be of variable length.

[0260] Regarding the current beam included as additional information, it is unclear whether it should be counted as one of the "N beams." Furthermore, since the current beam is evident from the perspective of the serving cell, it should also be clarified whether information about the current beam (i.e., SSBRI or CRI) is truly necessary.

[0261] Proposal 10: RAN2 should clarify whether the current beam counts as "N beams" and whether beam information (i.e., SSBRI / CRI) is truly necessary.

[0262] For the beam information field and beam quantity field, it should be assumed that the definition / specification of the CSI feedback should be reused. For the current bit widths, SSBRI and CRI depend on the configuration (i.e., the number of SSB / CSI-RS resources in the corresponding resource set), while RSRP and SINR are 7 bits each for absolute values ​​and 4 bits each for differential values.

[0263] RAN2 agreed that "a single MAC CE format for event-triggered L1 measurement reporting will be used for both SSB and CSI-RS reference signals." This is certainly possible because the bit widths of SSBRI and CRI are the same (when the same number of SSB and CSI-RS resources are configured). In this case, it will be discussed how the network knows whether the beam ID reported in MR MAC CE refers to SSBRI or CRI. If "triggered event information" is associated with a beam ID type (SSB or CSI-RS), the beam ID type reported in MR MAC CE can be implicitly known. However, this is only applicable to beams involved in event evaluation. Since RAN2 agreed that "the network controls whether beams that do not satisfy an event can report," "beams that do not satisfy an event" may not be involved in event evaluation (e.g., beams from serving cells / LTM candidate cells for different event evaluations, or beams from other neighboring cells). Therefore, depending on the type of beam the MR MAC CE can report, an explicit one-bit designation will be required for each beam ID within the MR MAC CE to distinguish whether the beam ID refers to SSBRI or CRI.

[0264] Furthermore, since the bit widths of L1-RSRP and L1-SINR are similarly the same, it is also possible to consider using the same format for both. In that case, a similar argument would be applicable, namely, a separate explicit one-bit designation would be needed for each beam quantity in MR MAC CE to distinguish whether the quantity refers to L1-RSRP or L1-SINR.

[0265] Proposal 11: RAN2 should agree that the same MR MAC CE format should be used for both measurements (i.e., L1-RSRP and L1-SINR).

[0266] Proposal 12: RAN2 should discuss whether an explicit one-bit indication is required in MR MAC CE to distinguish between SSB and CSI-RS (and, if agreed, to distinguish between L1-RSRP and L1-SINR).

[0267] Currently, the L1 filter is left to the implementation of the UE, and for Rel-19, "RAN2 assumes that filtering of the L1 measurement results is necessary. Whether a defined L1 filtering is required or whether it can be left to the implementation of the UE is up to RAN1." Regardless of whether the L1 filter is standardized or not, the filter coefficients change dynamically, for example, due to the movement speed of the UE. Therefore, reporting "L1 filter information," such as the number of L1-RSRP samples, may be useful because the gNB may optimize its own L1 filter when making cell switch decisions.

[0268] Proposal 13: RAN2 should discuss whether or not to report L1 filter information in MR MAC CE.

[0269] 1: Mobile communication system 5: Network 10: RAN 11: L1 filter 12: Beam integration / selection unit 13: L3 filter 14: Evaluation unit 15: L3 beam filter 16: Beam selection unit 20: CN 100: UE 110: Receiving unit 120: Transmitting unit 130: Control unit 140: Wireless communication unit 200: gNB 210: Transmitting unit 220: Receiving unit 230: Control unit 240: Network communication unit 241: Transmitting unit 242: Receiving unit 250: Wireless communication unit 300: AMF / UPF

Claims

A communication method performed by a user device in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), This involves performing event evaluation to determine whether the event conditions for sending a measurement report MAC (Medium Access Control) CE (Control Element), which stores beam measurement values ​​obtained from wireless quality measurements of the beam, to a network node have been met, and In response to the fulfillment of the aforementioned event conditions, a prioritization process is performed to select beam measurement values ​​from among the multiple beam measurement values ​​obtained by the wireless quality measurement to be stored in the measurement report MAC CE according to a predetermined priority order. This includes performing a transmission process to send the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to the network node. Communication method. 　 The aforementioned measurement report MAC CE is a truncated measurement report MAC CE that can be placed in the available space of a MAC PDU (Protocol Data Unit). The communication method according to claim 1. 　 The predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in descending order of value. The communication method according to claim 1. 　 The predetermined priority order is to prioritize storing beam measurement values ​​that satisfy the event conditions in the event evaluation into the measurement report MAC CE. The communication method according to claim 1. 　 The predetermined priority order is to store beam measurement values ​​in the measurement report MAC CE in order of the longest duration of the event conditions being met in the event evaluation. The communication method according to claim 1. 　 The predetermined priority order is to store the beam measurement values ​​in the measurement report MAC CE in descending order of the beam identifier values ​​set by the network node, either in descending order of value or in descending order of value. The communication method according to claim 1. 　 The aforementioned predetermined priority order is to store beam measurement values ​​in the measurement report MAC CE in the most recent order of the time when the event conditions were met during event evaluation. The communication method according to claim 1. 　 The user device, in response to the failure to meet predetermined reset conditions, stores unreported beam measurement values ​​in a measurement report MAC CE that is transmitted to the network node as a continuation of the previously transmitted measurement report MAC CE according to the priority order. The communication method according to claim 1. 　 The predetermined reset conditions are information for determining whether or not to reset the measurement report MAC CE to its initial transmission state. The predetermined reset conditions include at least one of the following: there are no unreported beam measurement values ​​for the network node; the maximum number of reportable beams set by the network node has been reached; a certain period of time has elapsed since the previous measurement report MAC CE transmission; new beam measurement values ​​have been acquired; and the network node has not set to continue transmitting the measurement report MAC CE. The communication method according to claim 8. 　 The user device receives information from the network node specifying some or all of the conditions included in the predetermined reset conditions. The communication method described in claim 9. 　 The user device stores SSBRI (SSB Reference signal Beam Identifier) ​​or CRI (CSI-RS Resource Indicator) as information regarding the type of beam measurement in the measurement report MAC CE. The communication method according to claim 1. 　 The user device stores beam measurement values ​​of the same type in the measurement report MAC CE. The communication method according to claim 1. 　 The user device stores identification information in the measurement report MAC CE indicating whether the type of L1 measurement result of the beam measurement value stored in the measurement report MAC CE is L1-RSRP (Reference Signal Received Power) or L1-SINR (Signal to Interference plus Noise Ratio). The communication method according to claim 1. 　 The user device stores beam measurement values ​​in the measurement report MAC CE that have the same L1 measurement result type as the beam measurement values ​​stored in the measurement report MAC CE. The communication method according to claim 1. 　 The user device, when the event condition is such that the serving cell beam deteriorates below an absolute threshold, stores the beam measurement value of the same type as the currently serving beam in the measurement report MAC CE. The communication method according to claim 1. 　 When the user device stores multiple beam measurement values ​​in the measurement report MAC CE, it stores information in the measurement report MAC CE indicating whether each stored beam measurement value is a beam measurement value for the same cell as the previous beam measurement value. The communication method according to claim 1. 　 When the user device stores the beam measurement values ​​of each of the multiple cells in the measurement report MAC CE, it stores the highest beam measurement value for each of the multiple cells in the measurement report MAC CE. The communication method according to claim 1. 　 Even if the network node has configured the user device to store the beam measurement information of the current serving beam in the measurement report MAC CE, the user device is controlled not to store the beam measurement information of the current serving beam in the measurement report MAC CE. The communication method according to claim 1. A user device used in a mobile communication system that supports LTM (L1 / L2-Triggered Mobility), A control unit performs an event evaluation to determine whether the event conditions for transmitting a measurement report MAC (Medium Access Control) CE (Control Element), which stores beam measurement values ​​obtained by wireless quality measurement of the beam, to a network node have been met, and performs a prioritization process to select beam measurement values ​​from among the multiple beam measurement values ​​obtained by the wireless quality measurement to be stored in the measurement report MAC CE, according to a predetermined priority order. The system includes a transmission unit that performs a transmission process to transmit the measurement report MAC CE containing the beam measurement values ​​selected by the prioritization process to the network node. User device.

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