Method and apparatus for improving layer 1 measurement and reporting for supporting inter-cell mobility based on layer 1 / layer 2 in next generation mobile communication system

Abstract

The present disclosure relates to: a communication technology in which a 5G communication system for supporting a higher data transmission rate than a 4G system is integrated with an IoT technology; and a system therefor. The present disclosure can be applied to intelligent services (e.g., smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security and safety-related services, etc.) based on the 5G communication technology and the IoT-related technology. The invention discloses a method and apparatus for measurement setting and reporting for inter-cell mobility.

Description

Technical Field

[0001] The present disclosure relates to measurement configuration and reporting for mobility between cells. Background Art

[0002] In order to meet the demand for wireless data services that have increased since the deployment of 4G communication systems, efforts have been made to develop improved 5G or quasi-5G communication systems. Therefore, 5G or quasi-5G communication systems are also referred to as "super 4G network" communication systems or "post-LTE" systems. 5G communication systems are considered to be implemented in ultra-high frequency (mmWave) bands (e.g., 60GHz bands) to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance of radio waves in ultra-high frequency bands, beamforming, massive multiple input multiple output (massive MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are being discussed in 5G communication systems. In addition, in 5G communication systems, based on evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, collaborative communications, coordinated multi-point (CoMP), receiving-end interference elimination, etc., technology development for system network improvement is underway. In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have also been developed as advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) have been developed as advanced access technologies.

[0003] The Internet is a human-centered connected network in which humans generate and consume information, and is now evolving into the Internet of Things (IoT), in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of IoT technology and big data processing technology through connection with cloud servers, etc., has emerged. Since IoT implementation requires technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology" and "security technology", sensor networks, machine-to-machine (M2M) communication, machine type communication (MTC), etc. have been studied recently. Such an IoT environment can provide intelligent Internet technology (IT) services that create new value for human life by collecting and analyzing data generated among connected things. Through the integration and combination between existing information technology (IT) and various industrial applications, IoT can be applied to various fields including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, health care, smart appliances, and advanced medical services.

[0004] In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine type communication (MTC), and machine-to-machine (M2M) communication are implemented through beamforming, MIMO, and array antenna technologies as 5G communication technologies. The application of cloud radio access network (cloud RAN), which is the above-mentioned big data processing technology, can also be considered as an example of the fusion of 5G technology and IoT technology.

[0005] Meanwhile, in order to support the communication of the UE using the best beam, the UE may be configured to measure the beam of a neighboring cell supporting beam switching while maintaining a connection state with a specific serving cell. At this time, it is required to improve the measurement and reporting method of the UE for cell switching. Summary of the invention

[0006] Technical issues

[0007] One aspect of the present disclosure is to provide a method for measuring and reporting beams belonging to other cells when a terminal receives a service from a current serving cell through a specific beam, and performing cell switching to the corresponding beam when the beam of the neighboring cell is better. The present disclosure is to solve the inefficiency caused by the long delay time according to the traditional cell switching process, and particularly proposes a method for measuring and reporting beams in order to move to a neighboring cell.

[0008] Solution to the problem

[0009] According to an embodiment of the present disclosure, a method for a base station in a wireless communication system for solving the problem may include: sending a radio resource control (RRC) message to a terminal, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell switching process, and receiving a report on layer 1 (L1) measurements of the candidate cell from the terminal based on the RRC message, wherein the second information may include cell configuration information of the candidate cell, and the report may be received by the serving cell based on the configuration of the measurement report included in the first information.

[0010] According to an embodiment of the present disclosure, a method for a terminal in a wireless communication system may include receiving a radio resource control (RRC) message from a base station, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell switching process, performing layer 1 (L1) measurement on the candidate cell based on the RRC message, and sending a report about the L1 measurement to the base station based on a configuration of the measurement report included in the first information, wherein the second information may include cell configuration information of the candidate cell.

[0011] According to an embodiment of the present disclosure, a base station in a wireless communication system may include a transceiver and a controller, the controller being configured to control the transceiver to send a radio resource control (RRC) message to a terminal, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell switching process, and to control the transceiver to receive a report on layer 1 (L1) measurement of the candidate cell from the terminal based on the RRC message, wherein the second information may include cell configuration information of the candidate cell, and the report may be received by the serving cell based on the configuration of the measurement report included in the first information.

[0012] According to an embodiment of the present disclosure, a terminal in a wireless communication system may include a transceiver and a controller, the controller being configured to control the transceiver to receive a radio resource control (RRC) message from a base station, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell switching process, perform layer 1 (L1) measurement on the candidate cell based on the RRC message, and control the transceiver to send a report about the L1 measurement to the base station based on a configuration of the measurement report included in the first information, wherein the second information may include cell configuration information of the candidate cell.

[0013] Advantageous Effects of the Invention

[0014] The present disclosure may provide a method that allows a terminal to measure a beam of a cell that is not a serving cell, and to determine a handover operation through such beam measurement by proposing a layer 1 measurement and reporting method for beam switching and handover based on layer 1 and layer 2 (L1 / L2). Therefore, there is an effect of supporting beam switching and handover operations to a neighboring cell through layer 1-based beam measurement, and enabling data transmission and reception after switching a beam to another cell by reducing a delay time compared to a conventional process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The structure of a next-generation mobile communication system to which the present disclosure is applied is shown.

[0016] Figure 2 A radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown.

[0017] Figure 3 The structure of another next-generation mobile communication system to which the present disclosure can be applied is shown.

[0018] Figure 4This is a scenario of beam management between cells involved in the present disclosure, and shows a scenario in which a user equipment (UE) sends and receives data based on L1 / L2 through the beam of a transmit / receive point (TRP) of an adjacent cell that supports beam change while maintaining a connection with a serving cell.

[0019] Figure 5a A scenario is shown in which an example UE according to the present disclosure switches a serving cell and a beam to the TRP of a cell supporting L1 / L2-based beam switching and sends and receives data.

[0020] Figure 5b A scenario is shown in which an example UE according to the present disclosure switches a serving cell and a beam to the TRP of a cell supporting L1 / L2-based beam switching and sends and receives data.

[0021] Figure 6 This disclosure shows Figure 4 The overall operation of inter-cell beam management in .

[0022] Figure 7 is Example 1 applied to the present disclosure, and shows the overall operation of performing switching after applying L1 / L2 inter-cell beam management.

[0023] Figure 8 is Example 2 applied to the present disclosure, and shows the overall operation of performing L1 / L2 inter-cell switching.

[0024] Fig. 9 An overall UE operation applied to an example of the present disclosure and in which L1 / L2-based beam switching and handover are performed, and specifically, a UE operation including a channel measurement and reporting method of the UE is shown.

[0025] Fig.10 An example BS operation applicable to the present disclosure is shown.

[0026] Fig.11 is a block diagram showing the internal structure of a UE to which the present disclosure is applied.

[0027] Fig.12 is a block diagram showing the configuration of a BS according to the present disclosure. DETAILED DESCRIPTION

[0028] Hereinafter, the operating principle of the present disclosure will be described in detail in conjunction with the accompanying drawings. When describing the present disclosure below, when it is determined that the description may make the subject matter of the present disclosure unnecessarily unclear, the detailed description of the known functions or configurations incorporated herein will be omitted. The terms to be described below are terms defined in consideration of the functions in the present disclosure, and may differ according to the user, the user's intention or habit. Therefore, the definition of the terms should be based on the content in the entire specification. In the following description, for the convenience of description, terms for identifying access nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are illustratively used. Therefore, the present disclosure is not limited by the terms described below, and other terms referring to subjects with equivalent technical meanings may also be used.

[0029] In the following description, for the convenience of description, the terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard will be used. However, the present disclosure is not limited to these terms and names and can be applied to systems conforming to other standards in the same manner.

[0030] Figure 1 The structure of a next-generation mobile communication system to which the present disclosure is applied is shown.

[0031] refer to Figure 1 As shown therein, the radio access network of the next generation mobile communication system includes a next generation base station (new radio node B, hereinafter referred to as NR NB) 1a-10, and a new radio core network (NR CN) or a next generation core network (NG CN) 1a-05. The user terminal (new radio user equipment, hereinafter referred to as NR UE or NR terminal) 1a-15 accesses the external network via the NR NB 1a-10 and the NR CN 1a-05.

[0032] exist Figure 1In the LTE system, NR NB 1a-10 corresponds to the evolved Node B (eNB) of the conventional LTE system. NR NB is connected to NR UE 1a-15 through a radio channel and can provide excellent services compared to the conventional Node B. In the LTE system, since all user services including real-time services (such as Voice over IP (VoIP) via Internet Protocol) are served through a shared channel, a device that collects status information (such as buffer status, available transmission power status, and channel status of UE) and performs scheduling accordingly is required, and NR NB 1a-10 is used as the device. Typically, one NR NB controls multiple cells. In order to achieve ultra-high-speed data transmission beyond the current LTE, the next generation mobile communication system can provide a wider bandwidth than the existing maximum bandwidth, can adopt orthogonal frequency division multiplexing (hereinafter referred to as OFDM) as a radio access technology, and can additionally integrate beamforming technology with it. In addition, the next generation mobile communication system adopts an adaptive modulation and coding (hereinafter referred to as AMC) scheme for determining the modulation scheme and channel coding rate according to the channel status of the UE. NR CN 1a-05 performs functions such as mobility support, bearer configuration, and QoS configuration. NR CN is a device responsible for various control functions and mobility management functions of UE, and is connected to multiple base stations. In addition, the next-generation mobile communication system can interoperate with the existing LTE system, and NR CN is connected to MME 1a-25 via a network interface. The mobility management entity (MME) is connected to eNB 1a-30, which is a traditional base station.

[0033] Figure 2 A radio protocol structure of a next-generation mobile communication system to which the present disclosure is applicable is shown.

[0034] refer to Figure 2 The radio protocols of the next-generation mobile communication system include NR Service Data Adaptation Protocol (SDAP) 1b-01 or 1b-45, NR Packet Data Convergence Protocol (PDCP) 1b-05 or 1b-40, NR Radio Link Control (RLC) 1b-10 or 1b-35, and NR Medium Access Control (MAC) 1b-15 or 1b-30 on each of the UE and NR base station sides.

[0035] The main functions of NR SDAP 1b-01 or 1b-45 may include some of the following.

[0036] User plane data transmission

[0037] Mapping between QoS flows and DRBs for both DL and UL

[0038] Marking QoS flow ID in DL and UL packets

[0039] Reflective QoS flow to DRB mapping for UL SDAP PDU

[0040] Regarding the SDAP layer device, whether the UE uses the header of the SDAP layer device or whether to use the function of the SDAP layer device for each PDCP layer device or each bearer or each logical channel can be configured through an RRC message, and if the SDAP header is configured, the non-access layer (NAS) QoS reflection configuration 1-bit indicator (NAS reflection QoS) and AS QoS reflection configuration 1-bit indicator (AS reflection QoS) of the SDAP header can be indicated, so that the UE can update or reconfigure the mapping information of the QoS flow and data bearer for the uplink and downlink. The SDAP header may include QoS flow ID information indicating QoS. QoS information can be used as data processing priority, scheduling information, etc. for smoothly supporting services.

[0041] The main functions of NR PDCP 1b-05 or 1b-40 may include the following functions.

[0042] Header compression and decompression: ROHC only

[0043] User plane data transmission

[0044] In-sequence delivery of upper layer PDUs

[0045] Out-of-order delivery of upper layer PDUs

[0046] · Reordering of received PDCP PDUs

[0047] Duplicate detection of lower layer SDUs

[0048] Retransmission of PDCP SDU

[0049] Encryption and decryption

[0050] Timer-based SDU discard in uplink

[0051] The reordering of the NR PDCP device refers to the function of reordering the PDCP PDU received from the lower layer in an order based on the PDCP sequence number (SN), and may include the function of transmitting data to the upper layer according to the rearranged order, may include the function of directly transmitting data without considering the order, may include the function of rearranging the order to record the lost PDCP PDU, may include the function of reporting the status of the lost PDCP PDU to the transmitting side, or may include the function of requesting retransmission of the lost PDCP PDU.

[0052] The main functions of NR RLC 1b-10 or 1b-35 may include some of the following functions.

[0053] Transmission of upper layer PDU

[0054] In-sequence delivery of upper layer PDUs

[0055] Out-of-order delivery of upper layer PDUs

[0056] Error correction through ARQ

[0057] Concatenation, segmentation and reassembly of RLC SDU

[0058] Re-segmentation of RLC data PDUs

[0059] Reordering of RLC data PDUs

[0060] Duplicate detection

[0061] Protocol error detection

[0062] RLC SDU discarded

[0063] RLC re-establishment

[0064] The in-sequence delivery of the NR RLC device refers to the function of transmitting the RLC SDU received from the lower layer to the upper layer in sequence, and may include the following functions: if an original RLC SDU is divided into several RLC SDUs and then an RLC SDU is received, then the several RLC SDUs are reassembled and the reassembled RLC SDU is transmitted, it may include the function of rearranging the received RLC PDU with reference to the RLC sequence number (SN) or the PDCP sequence number (SN), it may include the function of rearranging the order to record the lost RLC PDU, it may include the function of reporting the status of the lost RLC PDU to the transmitting side, it may include the following functions: if there is a lost RLC SDU, only the RLC SDU before the lost RLC SDRU is transmitted to the upper layer in sequence, it may include the following functions: although there is a lost RLC SDU, if the predetermined timer has expired, all RLC SDUs received before the timer is started are transmitted to the upper layer in sequence or it may include the following functions: although there is a lost RLC SDU, if the predetermined timer has expired, all RLC SDUs received until now are transmitted to the upper layer in sequence. In addition, the in-order delivery of the NR RLC device may include the function of processing the RLC PDU in the order of reception (regardless of the sequence number order, in the order of arrival) and delivering it to the PDCP device regardless of the order (out-of-order delivery), and may include the function of receiving the segment stored in the buffer or to be received later in the case of segmentation, reconfiguring it into a complete RLC PDU, processing it and delivering it to the PDCP device. The NR RLC layer may not include a cascading function, which may be performed in the NR MAC layer or replaced by a multiplexing function of the NR MAC layer.

[0065] Out-of-order delivery of the NR RLC device refers to the function of delivering the RLC SDU received from the lower layer to the upper layer immediately regardless of the order, which may include the function of reassembling and delivering multiple RLC SDUs into which an original RLC SDU has been segmented if it is received, and may include the function of storing the RLC SN or PDCP SN of the received RLC PDU and recording the RLC PDU lost due to reordering.

[0066] NR MAC 1b-15 or 1b-30 can be connected to multiple NR RLC layer devices configured in one UE, and the main functions of NR MAC can include some of the following functions.

[0067] Mapping between logical channels and transport channels

[0068] MAC SDU multiplexing / demultiplexing

[0069] Dispatch information report

[0070] Error correction through HARQ

[0071] Priority handling between logical channels of a UE

[0072] Priority handling between UEs with the help of dynamic scheduling

[0073] MBMS service identification

[0074] Transmission format selection

[0075] ·filling

[0076] The NR PHY layer 1b-20 or 1b-25 can perform operations of channel coding and modulating upper layer data to obtain OFDM symbols and deliver the OFDM symbols through the radio channel, or demodulate the OFDM symbols received through the radio channel, channel-decode them, and deliver them to the upper layer.

[0077] Figure 3 The structure of another next-generation mobile communication system to which the present disclosure can be applied is shown.

[0078] refer to Figure 3, a cell served by a beam-based NR gNB 1c-05 may include multiple transmit receive points (TRPs) 1c-10, 1c-15, 1c-20, 1c-25, 1c-30, 1c-35, and 1c-40. TRPs 1c-10 to 1c-40 indicate blocks that separate some functions of sending and receiving physical signals through a conventional NR gNB (eNB) and include multiple antennas. The NRgNB 1c-05 may be represented as a central unit (CU), and the TRP may be represented as a distributed unit (DU). The functions of the NR gNB 1c-05 and the TRP may be configured by separation of layers 1c-45 such as PDCP / RLC / MAC / PHY layers. That is, the TRP may have only a PHY layer and perform the functions of the corresponding layers, as shown in reference numerals 1c-15 and 1c-25, the TRP may have only a PHY layer and a MAC layer and perform the functions of the corresponding layers, as shown in reference numerals 1c-10, 1c-35, and 1c-40, and the TRP may have only a PHY layer, a MAC layer, and an RLC layer and perform the functions of the corresponding layers, as shown in reference numerals 1c-20 and 1c-30. Specifically, TRPs 1c-10 to 1c-40 can send and receive data using a beamforming technology that generates narrow beams in various directions through multiple transmit and receive antennas. UE 1c-50 accesses NR gNB 1c-05 and an external network through TRPs 1c-10 to 1c-40. In order to provide services to users, NR gNB 1c-05 collects and schedules UE status information such as buffer status, available transmit power status and channel status, and supports the connection between the UE and the core network (CN) (specifically, access and mobility management function (AMF) / session management function (SMF) 1c-50).

[0079] The TRP in the present disclosure is described based on structures 1c-15 and 1c-25 having only a PHY layer to perform the functions of the corresponding layer.

[0080] Figure 4 This is a scenario of beam management between cells involved in the present disclosure, and shows a scenario in which the UE sends and receives data based on L1 / L2 through the beam of the transmit / receive point (TRP) of an adjacent cell that supports beam switching while maintaining a connection with the serving cell.

[0081] Figure 4The case where multiple cells (TRP1-Cell1 and TRP2-Cell2) 1d-10 and 1d-15 exist within a distributed unit (DU) 1d-05 is shown, but the overall content of the present disclosure can be applied to the case between DUs (each DU constitutes a TRP-Cell). In addition, in the entirety of the present disclosure, a cell (TRP 2, Cell 2) that is not a service cell and supports L1 / L2-based mobility (beam switching and service cell switching) can be used interchangeably with an adjacent cell, a non-service cell, an additional cell with a physical cell ID (PCI) different from the service cell, etc.

[0082] In the conventional UE beam switching process 1d-45, the UE 1d-20 may send and receive data in a connected state through the TRP 1 1d-10 of the serving cell 1, and may be in a transmission configuration indicator (TCI) state 1 1d-25 and 1-30 corresponding to the best beam. In this operation, the UE may receive an indication of configuration information for L3 channel measurement (radio resource management (RRM)) of an additional cell (TRP2-cell 2) 1d-15 having a PCI different from that of the serving cell from the serving cell 1d-10 through RRC configuration information, and based thereon, perform an L3 measurement operation 1d-46 on the corresponding frequency and cell. Thereafter, in operation 1d-47, the serving cell (TRP 1-cell 1) 1d-10 may indicate a handover to the corresponding cell (TRP 2-cell 2) 1d-15 based on the measurement value reported by the UE, after which the handover of the UE is completed, and in operation 1d-48, additional RRC configuration information may be transmitted to the UE 1d-20 through TRP1-cell 2 1d-15. The RRC configuration information may include uplink (UL) / downlink (DL) configuration information and L1 measurement-related configuration (channel state information (CSI)-reference signal (RS) measurement and reporting) in the corresponding cell, and specifically, includes TCI state configuration information for the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH). In operation 1d-49, the UE performs L1 measurement according to the configuration, and in operation 1d-50, the gNB updates the TCI state through L1 / L2 signaling according to the measurement report of the UE. The TCI state 2 1d-40 corresponding to the best beam can be indicated to the UE. At this time, the serving cell of the UE is cell 1 before the handover, and cell 2 is the serving cell of the UE after the handover. That is, even after the handover, a lot of procedures and time are required to indicate the best beam to the UE.

[0083] Unlike the traditional UE beam switching process 1d-45, the improved beam switching scheme 1d-55 considered in the present disclosure is described below. Through the RRC configuration information 1d-56 from the serving cell 1d-10, the UE can refer to the corresponding serving cell to transmit the beam configuration associated with the additional cell (TRP 2-cell 2) 1d-15 having a PCI different from that of the serving cell. For example, a method for indicating the beam configuration associated with the additional cell (TRP 2-cell 2) 1d-15 having a PCI different from that of the serving cell is applied, that is, the TCI state corresponding to TRP2 associated with the new cell ID (physical cell ID (PCI); additional PCI-r17) is applied.

[0084]

[0085]

[0086] In addition, in order to manage the corresponding inter-cell beams, a unified TCI state framework is applied. The unified TCI state framework corresponds to applying a common TCI state framework to uplink and downlink as well as common channels and dedicated channels, where one of a joint UL / DL mode and a separate UL / DL mode can be configured.

[0087]

[0088] 1. Joint UL / DL mode: UL and DL are configured to share the same TCI configuration (in PDSCH-Config)

[0089]

[0090] 2. Separate UL / DL mode: UL and DL provide corresponding TCI configurations. The TCI state of DL follows the configuration in dl-OrJoint-TCIStateList-r17 (in PDSCH-Config), and the TCI state of UL follows ul-TCI-StateList-r17 (in BWP-UplinkDedicated).

[0091]

[0092]

[0093] In the RRC connection state with the serving cell 1, after providing the configuration for TRP 2-cell 2, in operation 1d-57, the UE performs L1 measurement on the corresponding TRP 2-cell 2 according to the configuration, and reports the corresponding result to the serving cell (cell 1) 1d-10. In operation 1d-58, when it is determined according to the measurement result that it is necessary to switch to a specific beam (TCI state 2) 1d-35 or 1d-40 of TRP 2 (cell 2) 1d-15 instead of the serving cell beam (TCI state 1) 1d-25 or 1d-30, the serving cell triggers beam switching and indicates the beam switching to the UE through L1 / L2 signaling. The UE can switch to the specific beam (TCI state 2) 1d-40 of TRP 2 (cell 2) 1d-15 through the corresponding indication, and perform physical channel configuration and higher layer configuration related to the configured beam. Due to the corresponding operation, the UE is in a connected state with the serving cell (cell 1) 1d-10, but performs data transmission and reception (receiving PDCCH / PDSCH and sending physical uplink control channel (PUCCH) / physical uplink shared channel (PUSCH)) through the channel link of TRP 2 (cell 2) 1d-15. That is, transmission and reception of common control channels are performed through the serving cell (cell 1) 1d-10. Thereafter, in operation 1d-59, the UE performs L3 measurement operation according to the measurement configuration configured in the independent service cell, and receives a switching command message from the serving base station (BS) (cell 1) (cell 1) in operation 1d-60 and can perform serving cell switching to cell 2. Through scheme 1d-55, the UE can perform data transmission and reception with a specific TRP 2 of cell 2 that supports L1 / L2-based mobility in a connected state with the serving cell, and continuously use the corresponding beam even after switching.

[0094] For reference, the configuration related to L1 measurement and reporting in operation 1d-57 and the RRC configuration used for the operation are described below. The corresponding contents are basically applied to the following embodiments of the present disclosure, and improved schemes can be added to the following embodiments.

[0095] 1.CSI measurement configuration

[0096] - CSI-RS resources and resource pools to be measured (NZP-CSI-RS, CSI-Interference Management (IM), and CSI-Synchronization Signal Block (SSB))

[0097] - CSI-RS resource configuration (aperiodic, semi-persistent) and trigger configuration to be measured

[0098] - When CSI-RS resources refer to SSB resources, additional PCI information can be provided to enable L1 measurements from neighboring cells (up to 7 neighboring cells (PCI) can be added to one serving cell)

[0099]

[0100]

[0101] 2.CSI report configuration

[0102] - Reporting types: periodic reporting, semi-persistent reporting for PUCCH, semi-persistent reporting for PUSCH, and aperiodic reporting for PUSCH

[0103] - Report quantity

[0104] - Other configurations required for reporting

[0105] Figure 5a and 5b is an embodiment considered in the present disclosure, and shows a scenario in which the UE switches the serving cell and beam to the TRP of a cell supporting L1 / L2 beam switching and sends and receives data.

[0106] The figure shows a situation in which multiple cells (TRP1-Cell1 and TRP2-Cell2) 1e-10, 1e-15, 1e-40 and 1e-45 exist within a distributed unit (DU) 1e-05 or 1e-35, but the overall content of the present disclosure can be applied to the situation between DUs (each DU constitutes a TRP-cell).

[0107] and Figure 4 Different from the traditional UE beam switching processes 1d-45 and 1d-55 described in the specification, the improved beam switching schemes 1e-25 and 1e-75 considered in the embodiments are described below.

[0108] 1. Example 1 1e-25: Performing L1 / L2 switching after inter-cell beam management (switching) operation

[0109] 2. Example 2 1e-75: Direct L1 / L2 switching

[0110] First, in reference Figure 5aIn the description of the overall operation of Example 1, in operation 1e-26, the UE may receive public configuration and dedicated configuration information about an additional cell (TRP 2-cell 2) 1e-15 having a PCI different from that of the serving cell from the serving cell 1e-10 through RRC configuration information. That is, configuration information corresponding to ServingCellID or candidateCellID (cell ID associated with PCI), ServingCellConfigCommon, and ServingCellConfig may be provided to the UE in advance. The corresponding configuration information may be provided in the form of a pre-configuration in the RRC configuration, and may include configuration information about multiple cells. In addition, the corresponding configuration includes all configuration information (cell configuration, bearer configuration, security key configuration, etc.) that is applied when the UE moves to (switches) the corresponding cell. The corresponding configuration includes Figure 4 The unified TCI state configuration and configuration related to L1 measurement and reporting described in operation 1d-56 of Figure 4 Compared with the conventional L1 / L2 measurement and reporting configuration and UE operation according thereto described in operation 1d-56 of FIG, the example of this figure details the L1 measurement and reporting configuration and the later UE operation for supporting L1 / L2-based switching. The detailed features are described in detail with reference to the following figures.

[0111] In the RRC connection state with the serving cell 1, after providing the configuration for TRP 2-cell 2 1e-15, in operation 1e-27, the UE performs L1 measurement on the corresponding TRP 2-cell 2 1e-15 according to the received configuration, and reports the corresponding result to the serving cell (cell 1) 1e-10. In operation 1e-28, when it is determined according to the measurement result that it is necessary to switch to a specific beam (TCI state 2) 1e-40 of TRP 2 (cell 2) 1e-15 instead of switching to the serving cell beam (TCI state 1) 1e-25, the serving cell triggers beam switching and indicates the beam switching to the UE through L1 / L2 signaling. The UE performs beam switching to TRP 2 (cell 2) 1e-15 through the corresponding indication, and performs data transmission and reception through the corresponding TRP 2 (cell 2) 1e-15 based on the switched beam. At this time, the serving cell switching is not performed, and the UE is still in the RRC connection state with the serving cell (cell 1) 1e-10. Thereafter, the UE performs L1 measurement on TRP 2-cell 2 1e-15 and reports the corresponding result to the serving cell (cell 1) 1e-10. When the L1 measurement reported by the UE meets the triggering condition for switching to TRP 2-cell 2 1e-15 (the detailed operation is described in detail below), the serving cell (cell 1) 1e-10 instructs the UE to switch. The corresponding indication may be an L1 / L2 message. That is, the MAC control element (CE) or the downlink control information (DCI) may include an indicator indicating the switching.

[0112] In reference Figure 5b In the description of the overall operation of Example 2, in operation 1e-76, the UE may receive public configuration and dedicated configuration information about an additional cell (TRP 2-cell 2) 1e-45 having a PCI different from that of the serving cell from the serving cell 1e-40 through RRC configuration information. That is, configuration information corresponding to ServingCellID or candidateCellID (cell ID associated with PCI), ServingCellConfigCommon, and ServingCellConfig may be provided to the UE in advance. The corresponding configuration information may be provided in the form of a pre-configuration in the RRC configuration, and may include configuration information about multiple cells. In addition, the corresponding configuration includes all configuration information (cell configuration, bearer configuration, security key configuration, etc.) that is applied when the UE moves to (switches) the corresponding cell. The corresponding configuration includes Figure 4 The unified TCI state configuration and configuration related to L1 measurement and reporting described in operation 1d-56 of Figure 4Compared with the conventional L1 measurement and reporting configuration described in operation 1d-56 of FIG. 1 and UE operation according thereto, the example of this figure details the L1 measurement and reporting configuration and the later UE operation for supporting L1 / L2-based switching. The detailed features are described in detail with reference to the following figures.

[0113] In the RRC connection state with the serving cell 1, after providing the configuration for TRP 2-cell 2 1e-45, in operation 1e-77, the UE performs L1 measurement on the corresponding TRP 2-cell 2 1e-45 according to the received configuration, and reports the corresponding result to the serving cell (cell 1) 1e-40. In operation 1e-78, when it is determined according to the measurement result that beam switching and switching to a specific beam (TCI state 2) 1e-70 of TRP 2 (cell 2) 1e-45 instead of to the serving cell beam (TCI state 1) 1e-45 are simultaneously required, the serving cell triggers the beam switching and switching, and indicates the beam switching and switching to the UE through L1 / L2 signaling. The UE simultaneously performs beam switching and switching to TRP 2 (cell 2) 1e-15 through the corresponding indication, and performs data transmission and reception through the corresponding TRP 2 (cell 2) 1e-15. At this time, in operation 1e-76, the UE applies the pre-configured configuration information to the target cell for handover. In the corresponding operation, the UE can perform random access to the target cell or omit the random access process according to whether uplink synchronization is required. The detailed operation is described in the following figures.

[0114] Figure 6 The present disclosure relates to Figure 4 The overall operation of inter-cell beam management in .

[0115] In the resident state 1f-10, in operation 1f-15, UE 1f-01 receives system information from cell 1 1f-02, and performs a transition process to the connected state (RRC connection establishment) in operation 1f-20. Thereafter, in operation 1f-25, the serving cell 1f-02 requests UE capabilities from the UE (sends a UE capability query message), and the UE transmits a UE capability information message including UE capabilities to the BS according to the request from the BS. The capability information of the corresponding UE may include information on whether L1 / L2-based inter-cell beam switching / management and switching are supported, and the UE sends at least one of UE-specific capabilities, frequency band-specific capabilities, and frequency band combination-specific capabilities as the corresponding UE capabilities through signaling. The serving cell 1f-02 may make a request (configuration request 1f-25) to the neighboring cell 2 1f-03 supporting L1 / L2-based mobility for the configuration information required for the corresponding UE to perform L1 / L2-based beam switching and switching, and in operation 1f-30, cell 2 1f-03 transmits a response (configuration response) message including the relevant configuration information to cell 1 1f-02 in response to the corresponding request. When cell 1 1f-02 and cell 2 1f-03 exist in one DU in the implementation of the network (intra-DU scenario), processes 1f-30 and 1f-35 may be omitted. In operation 1f-40, the serving cell may transmit the public / dedicated configuration information applied after the L1 / L2-based mobility (beam switching) to cell 2 1f-03 is indicated to the UE via an RRC reconfiguration message. For detailed configuration methods and contents, see Figure 4 Specifically, for the TCI state configuration, L1 measurement and reporting configuration provided in operation 1f-40, refer to Figure 4 In the above description, the number of neighboring cells may be multiple, and the serving cell may perform the same process as the multiple neighboring cells. For example, one serving cell may receive configurations of up to 7 neighboring cells.

[0116] Thereafter, in operation 1f-45, the UE performs L1 measurements associated with TRP2-cell 2 while maintaining a connection state with the serving cell 1f-02, and reports the corresponding measurement results to the serving cell 1f-02 according to a preset L1 measurement report configuration method in operation 1f-50. The serving cell 1f-02 can determine the beam switching of the corresponding UE based on the measurement results received from the UE, and when it is determined that a beam switching to a specific beam of TRP 2-cell 2 rather than to a specific beam of the serving cell (TRP1-cell 1) is required, in operation 1f-55, the TCI state switching of the UE to the target cell (TRP 2-cell 2) is indicated by L1 / L2 signaling. The L1 / L2 signaling in operation 1f-55 can be a MAC CE or a DCI, and information indicating the switching to the specific beam of TRP2-cell 2 is included in the corresponding signaling. At this time, when multiple TCI states are activated, the MAC CE can be used and one of the activated TCI states can be indicated by the DCI. Different from this, MAC CE can indicate only one TCI state. In this case, DCI is omitted. In operation 1f-60, the UE switches the beam to the indicated beam in TRP 2-cell 2 1f-03 and performs data transmission and reception through the corresponding beam. The UE maintains an RRC connection with the serving cell even during the operation.

[0117] Figure 7 is Example 1 applied to the present disclosure, and shows the overall operation of performing switching after applying L1 / L2 inter-cell beam management.

[0118] In the camping state 1g-10, in operation 1g-15, the UE 1g-01 receives system information from the cell 1 1g-02, and performs a transition process to the connected state in operation 1g-20. Thereafter, in operation 1g-25, the serving cell 1f-02 requests the UE for UE capabilities (sends a UE capability query message), and the UE transmits a UE capability information message including the UE capabilities according to the request from the BS. The capability information of the corresponding UE may include information indicating whether L1 / L2-based inter-cell beam switching / management and switching are supported, and the UE transmits at least one of UE-specific capabilities, frequency band-specific capabilities, and frequency band combination-specific capabilities as the capabilities of the corresponding UE through signaling. In operation 1g-25, the serving cell 1g-02 may make a request to the neighboring cell 2 1g-03 supporting L1 / L2-based mobility for configuration information required to perform L1 / L2-based beam switching and switching by the corresponding UE, and in operation 1g-30, the cell 2 1g-03 transmits a response message including the relevant configuration information in response to the corresponding request. When the cell 1 1g-02 and the cell 2 1g-03 exist in one DU in the implementation of the network (intra-DU scenario), the processes 1g-30 and 1g-35 may be omitted.

[0119] In operation 1g-40, the serving cell may transmit to the UE common / dedicated configuration information to be applied after L1 / L2-based mobility (beam switching and handover) to cell 2 1g-03 is indicated. Figure 6 The difference is that the common configuration and dedicated configuration information for the additional cell (TRP 2-cell 2) 1g-03 having a PCI different from the serving cell is included in operation 1g-40. That is, the configuration information corresponding to ServingCellID or candidateCellID (cell ID related to PCI), ServingCellConfigCommon and ServingCellConfig can be provided to the UE in advance. The corresponding configuration information can be provided in the form of pre-configuration in the RRC configuration, and can include configuration information about multiple cells. In addition, the corresponding configuration includes all configuration information (cell configuration, bearer configuration, security key configuration, etc.) that is applied when the UE moves to (switches) the corresponding cell. The corresponding configuration includes Figure 4 The unified TCI state configuration described in operation 1d-56 and the configuration related to L1 measurement and reporting.

[0120] This embodiment also proposes an improved method from the perspective of robustness to determine the movement (handover) between cells based on the L1 measurement of the UE. Typically, the L1 measurement includes a temporary report on the measured CSI-RS resource, and does not report the average or trend of the measurement value, and therefore when the L1 measurement is applied to the movement (handover) between cells, frequent handover operations (ping-pong phenomenon) between cells may occur. In order to solve this problem, the following method is proposed.

[0121] 1. First L1 measurement improvement method: BS processes and applies L1 measurement values ​​reported by UE

[0122] 1) The case where the L1 measurement value of the target cell reported by the UE is better than the L1 value of the serving cell for longer than a predetermined time (the reported L1 measurement of the target cell is large enough compared to the beam quality of the serving cell during the static time)

[0123] 2) The L1 measurement value of the target cell reported by the UE is better than the L1 value of the serving cell by a configured threshold for more than a predetermined number of times (the number of times the L1 measurement (e.g., counter) reported by the target cell is better than the beam of the serving cell exceeds a static value, e.g., 5 times in a row)

[0124] 3) BS derives cell quality from L1 measurements of target cell reported by UE and compares it with serving cell (NW derives cell quality using its own method based on reported L1 measurements and applies the same logic as 1) and 2) above). For example, N best beams exceeding a threshold are averaged to determine cell quality.

[0125] 2. Second L1 measurement improvement method: UE also sends additional information when reporting L1 measurement values

[0126] - Basically, L1 measurement and reporting configuration is provided separately in CSI measurement configuration. In CSI resource configuration, periodic, aperiodic or semi-periodic transmission of CSI resources can be configured, and UE measures the corresponding resources according to the configuration. In CSI reporting configuration, report types (periodic reporting, semi-periodic reporting for PUCCH, semi-periodic reporting for PUSCH and aperiodic reporting for PUSCH) are provided.

[0127] 1) The UE reports a timer value to indicate how long the L1 measurement value reported by the L1 measurement report is better than the L1 value of the serving cell by a threshold.

[0128] 2) The UE reports a counter value to indicate how many times the L1 measurement value reported by the L1 measurement report is better than the L1 value of the serving cell by a threshold. When the beam quality of the target cell is less than the L1 value of the serving cell or a value obtained by adding the L1 value to the threshold, the counter value is reset to 0. That is, it corresponds to the case where ping-pong occurs.

[0129] Note: If the beam quality between the serving cell and the target cell experiences ping-pong, the UE sets the counter to 0 whenever a ping-pong occurs.

[0130] 3) When a specific condition for allowing cell movement provided by the BS is met, the UE includes a 1-bit indicator indicating that the cell movement is met. The specific condition can be determined using the threshold of the timer and counter value described in 1) and 2). That is, the UE compares the threshold of the received timer and counter value with its own L1 measurement value and determines whether to include a 1-bit indicator.

[0131] 3. The third L1 measurement improvement method: applying both UE-based and BS-based methods

[0132] 4. Fourth L1 measurement improvement method: New conditions for triggering L1 reports (introduction of event-based L1 reports)

[0133] 1) The measurement values ​​of N beams of the neighboring cell are measured to exceed the threshold (N is configured by the BS, and the best beam of the neighboring cell is used when N is not configured)

[0134] 2) The measured values ​​of N beams of the neighboring cell are measured to be greater than the best beam of the serving cell by a threshold (N is configured by the BS, and the best beam of the neighboring cell is used when N is not configured)

[0135] - For both conditions, filtering configured by the BS can be applied to the L1 measurements (the filtering aims to increase robustness through the time averaging effect of the measurements and filtering with this effect is applied to the metric used)

[0136] - In addition, the condition can be triggered only when the quality of the serving cell is equal to or less than a certain threshold. The BS sends the relevant threshold as a configuration. This can be used to restrict movement between cells when the quality of the serving cell remains at a predetermined level.

[0137] - That is, when the quality of the serving cell is worse than the threshold (serving cell < threshold), the UE applies the criteria for L1 measurement value reporting for neighboring cells. The UE sends L1 measurement reports for neighboring cells. In cases other than this condition, the UE does not perform L1 measurement reporting for neighboring cells.

[0138] -For reference, the serving cell may be a cell linked to a neighboring cell or may be a SpCell.

[0139] Thereafter, the UE performs L1 measurements associated with TRP 2-cell 2 while maintaining a connection state with the serving cell 1g-02 in operation 1g-45, and reports the corresponding measurement results to the serving cell 1g-02 according to a preset L1 measurement report configuration method in operation 1g-50. One of the above methods (L1 measurement improvement method) can be applied to the L1 measurement value report. The serving cell 1g-02 can determine the beam switching of the UE based on the received measurement results, and when it is determined that a beam switching to a specific beam of TRP2-cell 2 rather than a specific beam of the serving cell (TRP1-cell 1) is required, instructs the UE to switch the TCI state to the target cell (TRP 2-cell 2) through L1 / L2 signaling in operation 1g-55. The L1 / L2 signaling in operation 1g-55 can be a MAC CE or a DCI, and information indicating switching to a specific beam of TRP 2-cell 2 is included in the corresponding signaling. At this time, when multiple TCI states are activated, MAC CE can be used and one of the activated TCI states can be indicated by DCI. Different from this, MAC CE can indicate only one TCI state. In this case, DCI is omitted. In operation 1g-60, the UE switches the beam to the indicated beam in TRP 2-cell 2 1g-03 and performs data transmission and reception through the corresponding beam. Even during operation, the UE maintains an RRC connection with the serving cell.

[0140] The UE even thereafter performs L1 measurements associated with TRP 2-cell 2 while maintaining a connection state with the serving cell 1g-02 according to the configuration, and reports the corresponding measurement results to the serving cell 1g-02 according to the preset L1 measurement report configuration method in operation 1g-65. One of the above methods (L1 measurement improvement method) can be applied to the L1 measurement value report. The serving cell 1g-02 can determine the cell switching (handover) of the UE based on the received measurement results, and simultaneously indicate the TCI state switching and switching of the UE to the target cell (TRP 2-cell 2) through L1 / L2 signaling in operation 1g-70. The L1 / L2 signaling in operation 1g-70 can be a MAC CE or a DCI, and information indicating the switching to a specific beam of TRP 2-cell 2 and the switching is included in the corresponding signaling. At this time, when multiple TCI states are activated, the MAC CE can be used and one of the activated TCI states can be indicated by the DCI. Alternatively, the MAC CE can indicate only one TCI state. In this case, the DCI is omitted. In operation 1g-75, the UE switches to TRP 2-Cell 2 1g-03, switches the beam to the indicated beam, and performs data transmission and reception through the corresponding beam.

[0141] Figure 8 is Example 2 applied to the present disclosure, and shows the overall operation of performing L1 / L2 inter-cell switching.

[0142] In operation 1h-15, in the resident state 1h-10, the UE 1h-01 receives system information from the cell 1 1h-02, and performs a transition process to the connected state in operation 1h-20. Thereafter, in operation 1h-25, the serving cell 1h-02 requests the UE for UE capabilities (sends a UE capability query message), and the UE transmits a UE capability information message including the UE capabilities to the BS according to the request from the BS. The capability information of the corresponding UE may include information indicating whether L1 / L2-based inter-cell beam switching / management and switching are supported, and the UE transmits at least one of UE-specific capabilities, band-specific capabilities, and band combination-specific capabilities as the capabilities of the corresponding UE through signaling. In operation 1h-25, the serving cell 1h-02 may make a request to the neighboring cell 2 1h-03 supporting L1 / L2-based mobility for configuration information required for performing beam switching and switching based on L1 / L2 through the corresponding UE, and in operation 1h-30, the cell 2 1h-03 transmits a response message including the relevant configuration information in response to the corresponding request. When the cell 1 1h-02 and the cell 2 1h-03 exist in one DU in the implementation of the network (intra-DU scenario), the processes 1h-30 and 1h-35 may be omitted.

[0143] In operation 1h-40, the serving cell may transmit to the UE common / dedicated configuration information to be applied after L1 / L2-based mobility (beam switching and handover) to cell 2 1h-03 is indicated. Figure 6 The difference is that the common configuration and dedicated configuration information for the additional cell (TRP 2-cell 2) 1h-03 having a PCI different from the serving cell is included in operation 1h-40. That is, the configuration information corresponding to ServingCellID or candidateCellID (cell ID related to PCI), ServingCellConfigCommon and ServingCellConfig can be provided to the UE in advance. The corresponding configuration information can be provided in the form of pre-configuration in the RRC configuration, and can include configuration information about multiple cells. In addition, the corresponding configuration includes all configuration information (cell configuration, bearer configuration, security key configuration, etc.) that is applied when the UE moves to (switches) the corresponding cell. The corresponding configuration includes Figure 4 The unified TCI state configuration described in operation 1d-56 and the configuration related to L1 measurement and reporting. This embodiment also proposes an improved method from the perspective of robustness to determine the movement (switching) between cells based on the L1 measurement of the UE. Typically, the L1 measurement includes a temporary report on the measured CSI-RS resources, and does not report the average value or trend of the measurement value, and therefore when the L1 measurement is applied to the movement (switching) between cells, frequent switching operations (ping-pong phenomenon) between cells may occur. In order to solve this problem, the following method is proposed.

[0144] 1. First L1 measurement improvement method: BS processes and applies L1 measurement values ​​reported by UE

[0145] 1) The case where the L1 measurement value of the target cell reported by the UE is better than the L1 value of the serving cell by a configured threshold for longer than a predetermined time (the reported L1 measurement of the target cell is large enough compared to the beam quality of the serving cell during the static time)

[0146] 2) The L1 measurement value of the target cell reported by the UE is better than the L1 value of the serving cell by a configured threshold for more than a predetermined number of times (the number of times the L1 measurement (e.g., counter) reported by the target cell is better than the beam of the serving cell exceeds a static value, e.g., 5 times in a row)

[0147] 3) BS derives cell quality from L1 measurements of target cell reported by UE and compares it with serving cell (NW derives cell quality using its own method based on reported L1 measurements and applies the same logic as 1) and 2) above). For example, N best beams exceeding a threshold are averaged to determine cell quality.

[0148] 2. The second L1 measurement improvement method: the UE also sends additional information when reporting the L1 measurement value.

[0149] - Basically, L1 measurement and reporting configuration is provided separately in CSI measurement configuration. In CSI resource configuration, periodic, aperiodic or semi-periodic transmission of CSI resources can be configured, and UE measures the corresponding resources according to the configuration. In CSI reporting configuration, report types (periodic reporting, semi-periodic reporting for PUCCH, semi-periodic reporting for PUSCH and aperiodic reporting for PUSCH) are provided.

[0150] 1) The UE reports a timer value to indicate how long the L1 measurement value reported by the L1 measurement report is better than the L1 value of the serving cell by a threshold.

[0151] 2) The UE reports a counter value to indicate how many times the L1 measurement value reported by the L1 measurement report is better than the L1 value of the serving cell by a threshold. When the beam quality of the target cell is less than the L1 value of the serving cell or a value obtained by adding the L1 value to the threshold, the counter value is reset to 0. That is, it corresponds to the case where ping-pong occurs.

[0152] Note: If the beam quality between the serving cell and the target cell experiences ping-pong, the UE sets the counter to 0 whenever a ping-pong occurs.

[0153] 3) When a specific condition for allowing cell movement provided by the BS is met, the UE includes a 1-bit indicator indicating that the cell movement is met. The specific condition can be determined using the threshold of the timer and counter value described in 1) and 2). That is, the UE compares the threshold of the received timer and counter value with its own L1 measurement value and determines whether to include a 1-bit indicator.

[0154] 3. The third L1 measurement improvement method: applying both UE-based and BS-based methods

[0155] 4. Fourth L1 measurement improvement method: New conditions for triggering L1 reports (introduction of event-based L1 reports)

[0156] 1) The measurement values ​​of N beams of the neighboring cell are measured to exceed the threshold (N is configured by the BS, and the best beam of the neighboring cell is used when N is not configured)

[0157] 2) The measured values ​​of N beams of the neighboring cell are measured to be greater than the best beam of the serving cell by a threshold (N is configured by the BS, and the best beam of the neighboring cell is used when N is not configured)

[0158] - For both conditions, filtering configured by the BS may be applied to the L1 measurements (the filtering aims to increase robustness through the time averaging effect of the measurements, and filtering with this effect is applied to the used metric).

[0159] - In addition, the condition can be triggered only when the quality of the serving cell is equal to or less than a certain threshold. The BS sends the relevant threshold as a configuration. This can be used to restrict inter-cell mobility when the quality of the serving cell remains at a predetermined level.

[0160] - That is, when the quality of the serving cell is worse than the threshold (serving cell < threshold), the UE applies the criteria for L1 measurement value reporting of neighboring cells. The UE performs L1 measurement reporting for neighboring cells. In cases other than this condition, the UE does not send L1 measurement reports for neighboring cells.

[0161] -For reference, the serving cell may be a cell linked to a neighboring cell or may be a SpCell.

[0162] Thereafter, the UE performs L1 measurements associated with TRP 2-cell 2 while maintaining a connection state with the serving cell 1h-02 in operation 1h-45, and reports the corresponding measurement results to the serving cell 1h-02 according to a preset L1 measurement report configuration method in operation 1h-50. One of the above methods (L1 measurement improvement method) can be applied to the L1 measurement value report. The serving cell 1h-02 can determine the cell switching (handover) of the UE based on the received measurement results, and in operation 1h-55, a handover negotiation process with the target cell is performed through a handover request 1h-55, and a configuration message receiving process 1h-60 is performed, and then in operation 1h-65, the TCI state switching and switching of the UE to the target cell TRP 2-cell 2 are simultaneously indicated through L1 / L2 signaling. For reference, operations 1h-50 and 1h-55 can be omitted, which corresponds to the situation within the DU in the network implementation or the situation where the relevant information in operation 1h-40 has been shared. The L1 / L2 signaling in operation 1h-70 may be a MAC CE or a DCI, and information indicating switching to a specific beam of TRP 2-cell 2 and switching is included in the corresponding signaling. At this time, when multiple TCI states are activated, MAC CE may be used and one of the activated TCI states may be indicated by DCI. Different from this, MAC CE may indicate only one TCI state. In this case, DCI is omitted. In operation 1h-75, the UE switches to TRP2-cell 2 1h-03, switches the beam to the indicated beam, and performs data transmission and reception through the corresponding beam.

[0163] Fig. 9An overall UE operation applied to an example of the present disclosure and in which L1 / L2-based beam switching and handover are performed, and specifically, a UE operation including a channel measurement and reporting method of the UE is shown.

[0164] In operation 1i-05, the UE in the connected state may receive the common / dedicated configuration information in the neighboring cell applied after the L1 / L2-based mobility is indicated from the serving cell through the RRC reconfiguration message. For detailed configuration method and content, refer to Figure 4 , Figure 5a , Figure 5b .

[0165] Thereafter, in operation 1i-10, the UE performs L1 measurement related to the candidate neighboring cell while maintaining the connection state with the serving cell, and reports the corresponding measurement result to the serving cell according to the preset L1 measurement report configuration method. Specifically, the detailed operations related to the L1 measurement configuration and reporting method in this operation can follow the above Figure 7 and Figure 8 .

[0166] The serving cell can determine whether to perform beam switching and switching of the UE based on the measurement results received from the UE, and when it is determined that switching to a specific beam of a neighboring cell is required instead of switching to a specific beam of the serving cell, the TCI state switching of the UE is indicated by L1 / L2 signaling in operation 1i-15. At this time, L1 / L2 signaling is different from traditional operation actions in that it can also trigger switching. L1 / L2 signaling can be MAC CE or DCI, and information indicating the switching of a specific beam of a neighboring cell and a serving cell is included in the corresponding signaling.

[0167] In operation 1i-20, the UE checks whether there is a handover indicator to a non-serving cell in the L1 / L2 signaling received in operation 1i-15, and performs different operations according to it. If it is configured to always perform a handover to the corresponding cell or a standard operation is determined when the L1 / L2 signaling is received, the UE operation of checking a separate handover indicator can be omitted.

[0168] When the switching indicator is included in the received MAC CE, the UE performs switching to the cell associated with the TCI state indicated in operation 1i-25, applies the configuration of the corresponding cell stored as preconfiguration according to the switching, and performs data transmission and reception using the indicated beam.

[0169] When the switching indicator is not included in the received MAC CE, the UE maintains the connection with the current serving cell and switches the beam to the TCI state of the indicated cell, and then performs data transmission and reception through the corresponding beam in operation 1i-30. After the beam switching, the UE performs data transmission and reception through the dedicated channels (PDCCH / PDSCH and PUCCH / PUSCH) of the corresponding beam.

[0170] In operation 1i-35, the UE performs L1 measurement and reporting for neighboring cells, as well as radio resource management (RRM) procedures, namely L2 measurement and channel reporting operations. Through the UE's L1 measurement report or L3 measurement report, the serving cell can indicate the need for handover to the neighboring cell by indicating to the UE in this operation.

[0171] In operation 1i-40, the UE may receive a switching command through L1 / L2 signaling or an RRC message, and when the UE receiving the switching command is already performing beam switching to a neighboring cell and performing data transmission and reception with the corresponding cell, operations related to random access may be omitted. The UE switches the serving cell according to the switching indication and releases the configuration of the previous serving cell.

[0172] Fig.10 An example BS operation applicable to the present disclosure is shown.

[0173] In operation 1j-05, the BS provides system information to the UE, and in operation 1j-10, the public / dedicated configuration information about the neighboring cells applied after the L1 / L2-based mobility is indicated is transmitted to the UE in the connected state through the RRC reconfiguration message provided by the serving cell. For detailed configuration methods and contents, refer to Figure 4 , Figure 5a , Figure 5b .

[0174] Thereafter, in operation 1j-15, the BS receives an L1 measurement value from the UE, in which case the measurement value may be a measurement value of a neighboring cell (non-serving cell) supporting L1 / L2-based mobility.

[0175] The serving cell can determine whether to perform beam switching of the UE based on the measurement results received from the UE, and when it is determined that switching to a specific beam of a neighboring cell rather than switching to a specific beam of the serving cell is required, the TCI state switching of the UE is indicated through L1 / L2 signaling in operation 1j-20. The L1 / L2 signaling can be a MAC CE or a DCI, and information indicating switching to a specific beam of the neighboring cell is included in the corresponding signaling. In addition, in the corresponding operation, the switching can also be indicated (simultaneously) through L1 / L2 signaling. When the switching is indicated at the same time, the serving cell performs the switching process, and deletes the context of the UE and releases the connection when the switching with the target cell is completed. At this time, the measurement value used to determine whether to perform the switching is the L1 measurement, and reference is made to the various methods proposed in connection with this. Figure 7 and Figure 8 .

[0176] When the L1 / L2 signaling does not include a handover process, in operation 1j-25, the serving cell maintains a connection state with the UE. In the corresponding operation, the UE performs data transmission and reception through dedicated channels (PDCCH / PDSCH and PUCCH / PUSCH) by applying the configuration information for presetting the neighboring cell. At this time, the UE can return to the current serving cell from the link to the neighboring cell.

[0177] In operation 1j-25, the serving cell may receive an additional L1 / L3 measurement report from a UE that is in a connected state with the UE, and when determining that the UE needs to be handed over to a neighboring cell, send a handover message to the corresponding UE and indicate the handover of the serving cell.

[0178] In operation 1j-30, when the UE switches the serving cell according to the switching indication, the UE releases the configuration of the previous serving cell.

[0179] Fig.11 is a block diagram showing the internal structure of a UE to which the present disclosure is applied.

[0180] refer to Fig.11 , the UE includes a radio frequency (RF) processing unit 1k-10, a baseband processing unit 1k-20, a storage unit 1k-30 and a controller 1k-40.

[0181] The RF processing unit 1k-10 performs functions for sending and receiving signals through a radio channel, such as frequency band conversion and amplification of signals. That is, the RF processing unit 1k-10 up-converts the baseband signal provided by the baseband processing unit 1k-20 to an RF band signal, transmits the RF band signal through an antenna, and then down-converts the RF band signal received by the antenna to a baseband signal. For example, the RF processing unit 1k-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Although only one antenna is shown in the accompanying drawings, the UE may include multiple antennas. The RF processing unit 1k-10 may include multiple RF chains. In addition, the RF processing unit 1k-10 may perform beamforming. For beamforming, the RF processing unit 1k-10 may control the phase and size of each signal sent / received by multiple antennas or antenna elements. The RF processing unit may perform MIMO and receive multiple layers when performing MIMO operations.

[0182] The baseband processing unit 1k-20 performs the function of conversion between the baseband signal and the bit stream according to the physical layer standard of the system. For example, in data transmission, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating the transmission bit stream. In addition, in data reception, the baseband processor 1k-20 reconstructs the received bit stream by demodulating and decoding the baseband signal provided from the RF processor 1k-10. For example, in an orthogonal frequency division multiplexing (OFDM) scheme, when transmitting data, the baseband processing unit 1k-20 generates complex symbols by encoding and modulating the transmission bit stream, maps the complex symbols to subcarriers, and then configures OFDM symbols by inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. In addition, when receiving data, the baseband processing unit 1k-20 divides the baseband signal provided from the RF processing unit 1k-10 in units of OFDM symbols, reconstructs the signal mapped to the subcarriers by a fast Fourier transform (FFT) operation, and then reconstructs the received bit stream by demodulation and decoding.

[0183] The baseband processing unit 1k-20 and the RF processing unit 1k-10 can send and receive signals as described above. Therefore, each of the baseband processing unit 1k-20 and the RF processing unit 1k-10 can be referred to as a transmitter, a receiver, a transceiver or a communication unit. In addition, at least one of the baseband processing unit 1k-20 and the RF processing unit 1k-10 may include a plurality of communication modules for supporting a plurality of different radio access technologies. At least one of the baseband processing unit 1k-20 and the RF processing unit 1k-10 may include different communication modules for processing signals in different frequency bands. For example, different radio access technologies may include wireless LANs (e.g., IEEE 802.11) and cellular networks (e.g., LTE). In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.NRHz, NRhz) bands and millimeter (mm) wave (e.g., 60GHz) bands.

[0184] The storage unit 1k-30 stores data such as basic programs, applications, and configuration information for the operation of the UE. Specifically, the storage unit 1k-30 can store information related to a second access node that performs wireless communication via a second radio access technology. The storage unit 1k-30 provides the stored data in response to a request from the controller 1k-40.

[0185] The controller 1k-40 controls the overall operation of the UE. For example, the controller 1k-40 sends and receives signals through the baseband processing unit 1k-20 and the RF processing unit 1k-10. The controller 1k-40 records data in the storage unit 1k-30 and reads the data. To this end, the controller 1k-40 may include at least one processor. For example, the controller 1k-40 may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls a higher layer such as an application layer.

[0186] Fig.12 is a block diagram showing a configuration of a base station according to the present disclosure.

[0187] like Fig.12 As shown, the base station includes an RF processing unit 1l-10, a baseband processing unit 1l-20, a backhaul communication unit 1l-30, a storage unit 1l-40 and a controller 1l-50.

[0188] The RF processor 11-10 performs functions for sending and receiving signals through a wireless channel, such as frequency band conversion and signal amplification. That is, the RF processing unit 11-10 up-converts the baseband signal provided by the baseband processing unit 11-20 into an RF band signal, transmits the RF band signal through an antenna, and then down-converts the RF band signal received by the antenna into a baseband signal. For example, the RF processing unit 11-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. Although only one antenna is shown in the accompanying drawings, the first access node may include multiple antennas. In addition, the RF processing unit 11-10 may include multiple RF chains. The RF processing unit 11-10 may perform beamforming. For beamforming, the RF processing unit 11-10 may control the phase and size of each signal sent and received by multiple antennas or antenna elements. The RF processing unit may perform downlink MIMO operations by sending one or more layers.

[0189] The baseband processing unit 11-20 performs the function of performing conversion between the baseband signal and the bit stream according to the physical layer standard of the first radio access technology. For example, when sending data, the baseband processing unit 11-20 generates complex symbols by encoding and modulating the transmission bit stream. In addition, when receiving data, the baseband processing unit 11-20 reconstructs the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit 11-10. For example, in the OFDM scheme, when sending data, the baseband processing unit 11-20 can generate complex symbols by encoding and modulating the transmission bit stream, mapping the complex symbols to subcarriers, and then configuring OFDM symbols through IFFT operations and CP insertion. In addition, when receiving data, the baseband processing unit 11-20 divides the baseband signal provided from the RF processing unit 11-10 in units of OFDM symbols, recovers the signal mapped with subcarriers through FFT operations, and then recovers the received bit string through demodulation and decoding. As described above, the baseband processing unit 11-20 and the RF processing unit 11-10 transmit and receive signals. Therefore, the baseband processing unit 11-20 and the RF processing unit 11-10 can be referred to as a transmitter, a receiver, a transceiver, a communication unit, or a wireless communication unit.

[0190] The backhaul communication unit 11-30 provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit 11-30 converts a bit stream sent from the master base station to another node (e.g., a secondary base station or a core network) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0191] The storage unit 11-40 stores data such as basic programs, applications, and setting information for the operation of the main base station. Specifically, the storage unit 11-40 can store information about the bearer assigned to the accessed UE and the measurement results reported from the accessed UE. In addition, the storage unit 11-40 can store information as a reference for determining whether to allow or interrupt multiple accesses to the UE. The storage unit 11-40 provides the stored data according to a request from the controller 11-50.

[0192] The controller 11-50 controls the overall operation of the main base station. For example, the controller 11-50 sends and receives signals through the baseband processor 11-20 and the RF processor 11-10 or through the backhaul communication unit 11-30. In addition, the controller 11-50 records data in the storage unit 11-40 and reads data. To this end, the controller 11-50 may include at least one processor.

[0193] The embodiments of the present disclosure described and shown in the specification and the drawings are only specific examples presented to easily explain the technical content of the embodiments of the present disclosure and to help understand the embodiments of the present disclosure, and are not intended to limit the scope of the embodiments of the present disclosure. That is, it is obvious to those skilled in the art that other variations based on the technical ideas of the present disclosure can be implemented. In addition, the above-mentioned various embodiments can be used in combination as needed. For example, a part of an embodiment of the present disclosure can be combined with a part of another embodiment to operate a base station and a terminal. In addition, the embodiments of the present disclosure can be applied to other communication systems, and other variations based on the technical ideas of the embodiments can also be implemented. For example, the embodiments can be applied to LTE, 5G, NR or 6G systems. Therefore, the scope of the present disclosure should not be limited to the embodiments set forth herein, but should be defined by the attached claims and their equivalents.

Claims

1. A method for a base station in a wireless communication system, the method comprising: sending a radio resource control (RRC) message to a terminal, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell handover procedure; as well as receiving, from the terminal, a report on layer 1 (L1) measurements for a candidate cell based on an RRC message, The second information includes the cell configuration information of the candidate cell, and The report is received by the serving cell based on a configuration of the measurement report included in the first information.

2. The method according to claim 1, wherein: L1 measurements are based on the configuration of the Transmission Configuration Indicator (TCI) state associated with the candidate cell.

3. The method according to claim 1, comprising: sending information to the terminal about the conditions for triggering the transmission of the report, The information is configured for at least one of a threshold of the strength of the L1 measurement and a time of the L1 measurement.

4. The method according to claim 3, wherein: The report includes a timer value indicating the time of the L1 measurement.

5. A method for a terminal in a wireless communication system, the method comprising: receiving a radio resource control (RRC) message from a base station, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell handover procedure; Based on the RRC message, perform layer 1 (L1) measurement on the candidate cell; as well as sending a report on L1 measurement to the base station based on the configuration of the measurement report included in the first information, The second information includes cell configuration information of the candidate cell.

6. The method according to claim 5, wherein: L1 measurements are performed based on the configuration of the Transmission Configuration Indicator (TCI) state associated with the candidate cell.

7. The method according to claim 5, comprising: receiving information from a base station regarding conditions for triggering transmission of a report, The information is configured for at least one of a threshold of the strength of the L1 measurement and a time of the L1 measurement.

8. The method according to claim 6, wherein: The report includes a timer value indicating the time of the L1 measurement.

9. A base station in a wireless communication system, the base station comprising: Transceiver; and a controller configured to control the transceiver to send a radio resource control (RRC) message to a terminal, the RRC message including first information about a serving cell for serving the terminal and second information about a candidate cell related to a cell handover procedure, and to control the transceiver to receive a report about layer 1 (L1) measurement for the candidate cell from the terminal based on the RRC message, The second information includes the cell configuration information of the candidate cell, and The report is received by the serving cell based on a configuration of the measurement report included in the first information.

10. The base station according to claim 9, wherein: L1 measurements are based on the configuration of the Transmission Configuration Indicator (TCI) state associated with the candidate cell.

11. The base station according to claim 9, wherein: The controller is configured to control the transceiver to send information about a condition for triggering transmission of a report to the terminal, and The information is configured for at least one of a threshold of the strength of the L1 measurement and a time of the L1 measurement.

12. The base station according to claim 11, wherein: The report includes a timer value indicating the time of the L1 measurement.

13. A terminal in a wireless communication system, the terminal comprising: Transceiver; and a controller configured to control the transceiver to receive a radio resource control (RRC) message from a base station, the RRC message including first information about a serving cell for serving a terminal and second information about a candidate cell related to a cell handover procedure, perform layer 1 (L1) measurement on the candidate cell based on the RRC message, and control the transceiver to send a report on the L1 measurement to the base station based on a configuration of a measurement report included in the first information, The second information includes cell configuration information of the candidate cell.

14. The terminal according to claim 13, wherein: L1 measurements are performed based on the configuration of the Transmission Configuration Indicator (TCI) state associated with the candidate cell.

15. The terminal according to claim 13, wherein: The controller is configured to control the transceiver to receive information about conditions for triggering transmission of a report from the base station, wherein the information is configured for at least one of a threshold value of the intensity of the L1 measurement and a time of the L1 measurement, and Among other things, the report includes a timer value indicating the time of the L1 measurement.

Images