Method and apparatus for beam management in wireless communication system

Abstract

The method for beam adjustment in a base station disclosed herein may comprise the steps of: allocating a first resource for transmitting a candidate beam determined on the basis of the number of scans and the number of subcarriers of a beam skewed in an angle search space; sending first resource information indicating the allocated first resource to the terminal; mapping a beam index to each of the candidate beams; transmitting, to the terminal, information on a beam index mapped to each of the candidate beams; transmitting the reference signal by using the first resource; receiving reception quality information for the reference signal from the terminal; and determining a transmission beam on the basis of the receiving quality information.

Description

Technical Field

[0001] The present invention relates to enhanced communication technology, and more particularly, to beam management technology in a wireless communication system. Background Art

[0002] Communication networks (e.g., 5G communication networks or 6G communication networks) are being developed to provide enhanced communication services compared to existing communication networks (e.g., long term evolution (LTE), LTE-Advanced, etc.). 5G communication networks (e.g., New Radio (NR) communication networks) can support frequency bands below 6 GHz and frequency bands above 6 GHz. In other words, 5G communication networks can support frequency region 1 (FR1) bands and / or FR2 bands. Compared with LTE communication networks, 5G communication networks can support various communication services and scenarios. For example, usage scenarios of 5G communication networks may include enhanced Mobile BroadBand (eMBB), UltraReliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), etc.

[0003] Compared with 5G communication networks, 6G communication networks can support a wide variety of communication services and scenarios. 6G communication networks can meet the requirements of ultra-performance, ultra-bandwidth, ultra-space, ultra-precision, ultra-intelligence and / or ultra-reliability. 6G communication networks can support multiple broadband bands and can be applied to various usage scenarios, such as terrestrial communication, non-terrestrial communication, sidelink communication, etc.

[0004] On the other hand, in 5G NR, the operating frequency band is defined as being divided into FR1 band n1 to n99 and FR2 band n257 to n262. In addition, 5G NR has introduced and adopted beamforming technology to solve the path loss problem that occurs when utilizing a higher frequency band such as FR2, and effectively deliver desired information in a specific direction.

[0005] According to the 5G NR standard, the beam management process for beamforming includes an initial beam establishment process, a beam adjustment process, and a beam recovery process. The initial beam establishment process selects a wide beam by combining a synchronization signal block (SSB) time index and a RACH opportunity; the beam adjustment process refines a narrower and more precise beam after the initial beam establishment process; and the beam recovery process selects a new beam when performance deteriorates due to beam misalignment.

[0006] In the initial beam establishment and beam adjustment process, the base station or terminal sequentially changes its beams one by one based on beam scanning, measures the performance of its candidate beams, and identifies the best beam. Since only one beam is formed at a time for performance measurement during beam scanning, existing beam management methods require time proportional to the number of candidate beams formed by the base station and the terminal to identify the best beam.

[0007] In future 6G communication systems, it is expected that the millimeter wave unlicensed frequency band or the terahertz frequency band will be utilized to realize ultra-high capacity, ultra-wideband and ultra-low latency communication services. When utilizing extremely high frequency bands in 6G communications, it is expected that more antennas than in 5G NR will be used to form highly directional beams to solve the significant path loss problem inherent in high frequency bands.

[0008] Furthermore, if 6G employs more antennas than 5G NR, it is expected that narrower beams will be formed than those used in the beam management process of 5G NR, requiring a greater number of SSB / CSI-RS candidate beams. If the current 5G NR beam scanning scheme is used to identify the best beam in a 6G system, significantly more time resources may be required compared to 5G, potentially resulting in a substantial increase in time overhead.

[0009] Therefore, in 6G communication systems that require a higher level of ultra-low latency communication, the current 5G NR beam management process is not suitable, and it is necessary to define a beam management process and required parameters dedicated to low latency communication in the terahertz band, which is different from the beam scanning-based method of 5G NR. Summary of the invention

[0010] Technical issues

[0011] The present invention is directed to providing a method and apparatus for beam management in a communication system utilizing a high frequency band.

[0012] Technical Solution

[0013] A method of a base station according to an exemplary embodiment of the present invention may include: allocating a first resource for sending a candidate beam, wherein the candidate beam is determined based on the number of subcarriers to be deflected by the beam within an angle search space and the number of beam scans formed using the subcarriers to be deflected by the beam; sending first resource information indicating the allocated first resource to a user equipment (UE); mapping a beam index to each of the candidate beams; sending information about the beam index mapped to each of the candidate beams to the UE; sending a first reference signal through the candidate beam using the first resource; receiving reception quality information for the first reference signal from the UE; and determining a transmitting beam based on the reception quality information.

[0014] The first resource information may indicate frequency resources and time resources, each of the frequency resources may correspond to the frequency of each of the subcarriers used to form the candidate beams, and each of the time resources may correspond to the transmission time of each of the candidate beams based on the number of scans.

[0015] The frequencies of the subcarriers may be configured such that the differences between the frequencies of adjacent subcarriers have the same value.

[0016] When the first reference signal is transmitted through the candidate beams, a time delay network (TDN) function may be controlled so that main lobes of the candidate beams do not overlap with each other and angles between the candidate beams have a uniform angle difference.

[0017] First resource information allocated to candidate beams and information about each of the beam indexes mapped to the candidate beams may be sent to the UE using at least one of downlink control information (DCI), medium access control-control element (MAC-CE), or radio resource control (RRC) reconfiguration information.

[0018] The method may further include: receiving information about the number of candidate beams of the UE from the UE; determining a second resource for sending a second reference signal based on the number of candidate beams of the UE; and sending the second reference signal to the UE using the determined second resource.

[0019] The method may further include, when sending the second reference signal through the transmit beam, indicating that the transmit beam is fixed by utilizing a repetition parameter in an information element of a reference signal resource set of RRC reconfiguration information before sending the second reference signal to the UE.

[0020] The information about the number of candidate beams of the UE may be received using at least one of uplink control information (UCI), UE assistance information, or UE performance information.

[0021] A method of a user equipment (UE) according to an exemplary embodiment of the present invention may include: receiving first resource information from a base station, the first resource information indicating a first resource allocated to a candidate beam sent by the base station; receiving information about a beam index mapped to each of the candidate beams from the base station; receiving a first signal from the base station through the candidate beam using a preconfigured receiving beam, the first signal including a first reference signal and information about a beam index corresponding to each of the candidate beams; measuring the reception quality of the first reference signal received through each of the candidate beams; and sending information about the measured reception quality and information about the index of each of the candidate beams corresponding to the measured reception quality to the base station, wherein the candidate beam can be determined based on the number of subcarriers to be beam-deflected within an angle search space and the number of beam scans formed using the subcarriers to be beam-deflected.

[0022] The first resource information may indicate frequency resources and time resources, each of the frequency resources may correspond to the frequency of each of the subcarriers used to form the candidate beams, and each of the time resources may correspond to the transmission time of each of the candidate beams based on the number of scans.

[0023] The frequencies of the subcarriers may be configured such that the differences between the frequencies of adjacent subcarriers have the same value.

[0024] First resource information allocated to candidate beams and each of information of a beam index indicated by a first signal received through each of the candidate beams can be received using at least one of downlink control information (DCI), medium access control-control element (MAC-CE), or radio resource control (RRC) reconfiguration information.

[0025] The method may further include: determining a UE candidate beam group by dividing a preconfigured receiving beam into a plurality of subdivided beams; sending information about the number of beams of the UE candidate beam group to a base station; receiving a second reference signal using a beam belonging to the UE candidate beam group; measuring a signal quality of the second reference signal; and determining the receiving beam based on the measured signal quality of the second reference signal.

[0026] The method may further include: receiving second information before receiving the second reference signal, the second information indicating that the transmit beam is fixed.

[0027] The second information may be indicated by using a repetition parameter in an information element of a reference signal resource set of the RRC reconfiguration information.

[0028] The information about the number of candidate beams of the UE may be transmitted using at least one of uplink control information (UCI), UE assistance information, or UE performance information.

[0029] According to an exemplary embodiment of the present invention, a user equipment (UE) may include at least one processor, wherein the at least one processor enables the UE to execute: receiving first resource information from a base station, the first resource information indicating a first resource allocated to a candidate beam sent by the base station; receiving information about a beam index mapped to each of the candidate beams from the base station; receiving a first signal from the base station through the candidate beam using a preconfigured receiving beam, the first signal including a first reference signal and information about a beam index corresponding to each of the candidate beams; measuring the reception quality of the first reference signal received through each of the candidate beams; and sending information about the measured reception quality and information about the index of each of the candidate beams corresponding to the measured reception quality to the base station, wherein the candidate beam may be determined based on the number of subcarriers to be beam deflected within an angle search space and the number of beam scans formed using the subcarriers to be beam deflected.

[0030] The first resource information may indicate frequency resources and time resources, each of the frequency resources may correspond to the frequency of each of the subcarriers used to form the candidate beams, and each of the time resources may correspond to the transmission time of each of the candidate beams based on the number of scans.

[0031] At least one processor may further cause the UE to perform: determining a UE candidate beam group by dividing a preconfigured receive beam into a plurality of subdivided beams; sending information about the number of beams of the UE candidate beam group to a base station; receiving a second reference signal using a beam belonging to the UE candidate beam group; measuring a signal quality of the second reference signal; and determining a receive beam based on the measured signal quality of the second reference signal.

[0032] At least one processor may further cause the UE to execute: receiving second information before receiving a second reference signal, wherein the second information indicates that the transmit beam is fixed, wherein the second information may be indicated by utilizing a repetition parameter in an information element of a reference signal resource set of the RRC reconfiguration information.

[0033] Beneficial Effects

[0034] According to the present invention, multiple beams can be sent simultaneously in different directions using beam deflection. By controlling the angles of the beams sent simultaneously via the TDN function, the beam angles can be controlled to be uniform. In addition, when beam adjustment and beam recovery processes are performed using beams sent simultaneously, beam adjustment and recovery can be performed faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0036] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0037] Figure 3 is a block diagram illustrating a first exemplary embodiment of a communication node performing communications.

[0038] Figure 4a is a block diagram illustrating a first exemplary implementation of a transmit path.

[0039] Figure 4b is a block diagram illustrating a first exemplary implementation of a receive path.

[0040] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a system frame in a communication system.

[0041] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a subframe in a communication system.

[0042] Figure 7 is a conceptual diagram illustrating a first exemplary embodiment of a time slot in a communication system.

[0043] Figure 8 is a conceptual diagram illustrating a first exemplary implementation of time-frequency resources in a communication system.

[0044] Figure 9a is a conceptual diagram illustrating a beam skew phenomenon when a base station transmits beams using multiple antennas.

[0045] Figure 9b is a conceptual diagram showing a situation in which, when beams are transmitted using a plurality of antennas at a base station, a slanted beam is aligned with a direction of a reference beam.

[0046] Fig.10 is a conceptual diagram showing a case where, when beams are transmitted using multiple antennas at a base station, a TDN function is dynamically controlled to simultaneously form multiple beams in desired directions.

[0047] Fig.11 This is a conceptual diagram showing a case where a base station allocates transmission beam resources using beam deflection.

[0048] Fig.12 is a conceptual diagram showing the overall process of low-latency beam adjustment using beam deflection.

[0049] Fig.13 is a sequence diagram illustrating a method of low-latency beam adjustment using beam deflection.

[0050] Fig.14 is a conceptual diagram showing the overall process of low-latency beam recovery using beam deflection.

[0051] Fig.15 is a sequence diagram illustrating a low-latency beam adjustment method using beam deflection. DETAILED DESCRIPTION

[0052] Since the present invention can be variously modified and can have multiple forms, specific exemplary embodiments will be shown in the drawings and described in detail in the specific embodiments. However, it should be understood that it is not intended to limit the present invention to specific exemplary embodiments, but on the contrary, the present invention covers all modifications and alternative forms that fall within the spirit and scope of the present invention.

[0053] Relational terms such as first, second, etc. can be used to describe various elements, but these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, a first component can be named as a second component, and the second component can also be similarly named as the first component. The term "and / or" means any one or combination of multiple related and described matters.

[0054] In the present invention, "at least one of A and B" may mean "at least one of A or B" or "at least one of a combination of one or more of A and B". In addition, "one or more of A and B" may mean "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0055] In the present invention, "(re)transmission" may refer to "transmission", "retransmission" or "transmission and retransmission", "(re)configuration" may refer to "configuration", "reconfiguration" or "configuration and reconfiguration", "(re)connection" may refer to "connection", "reconnection" or "connection and reconnection", and "(re)access" may refer to "access", "reaccess" or "access and reaccess".

[0056] When it is mentioned that a certain component is "coupled" or "connected" to another component, it should be understood that the certain component is directly "coupled" or "connected" to the other component, or another component may be provided therebetween. On the contrary, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it should be understood that no other component is provided therebetween.

[0057] The terms used in the present invention are only used to describe specific exemplary embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "including" or "having" are intended to indicate the presence of features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, but it should be understood that these terms do not exclude the presence or addition of one or more features, quantities, steps, operations, components, parts, or combinations thereof.

[0058] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as those generally understood by those of ordinary skill in the art to which the present invention belongs. Terms commonly used in dictionaries and already in dictionaries should be interpreted as having meanings that match the contextual meanings in the art. In this specification, unless explicitly defined, terms are not necessarily interpreted as having formal meanings.

[0059] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate a comprehensive understanding of the present invention, the same reference numerals refer to the same elements in the description of the entire accompanying drawings, and repeated descriptions thereof will be omitted. Operations of the exemplary embodiments clearly described in the present invention and combinations of the exemplary embodiments, expansions of the exemplary embodiments, and / or variants of the exemplary implementations may be performed. Some operations may be omitted, and the sequence of operations may be changed.

[0060] Even when a method (e.g., transmission or reception of a signal) performed at a first communication node among communication nodes is described in an exemplary embodiment, a corresponding second communication node may perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when the operation of a user equipment (UE) is described, a base station corresponding thereto may perform an operation corresponding to the operation of the UE. Conversely, when the operation of a base station is described, a corresponding UE may perform an operation corresponding to the operation of the base station.

[0061] A base station may be referred to by various terms, such as node B, evolved node B, next generation node B (gNodeB), gNB, equipment, device, node, communication node, base transceiver station (BTS), radio remote head (RRH), transmission reception point (TRP), radio unit (RU), roadside unit (RSU), radio transceiver, access point, access node, etc. User equipment (UE) may be referred to by various terms, such as terminal, equipment, device, node, communication node, end node, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, on-board unit (OBU), etc.

[0062] In the present invention, signaling may be one of higher layer signaling, MAC signaling and physical (PHY) signaling, or a combination of two or more. A message for higher layer signaling may be referred to as a "higher layer message" or a "higher layer signaling message". A message for MAC signaling may be referred to as a "MAC message" or a "MAC signaling message". A message for PHY signaling may be referred to as a "PHY message" or a "PHY signaling message". Higher layer signaling may refer to the operation of sending and receiving system information (e.g., a master information block (MIB), a system information block (SIB)) and / or an RRC message. MAC signaling may refer to the operation of sending and receiving a MAC control element (CE). PHY signaling may refer to the operation of sending and receiving control information (e.g., downlink control information (DCI), uplink control information (UCI) or sidelink control information (SCI)).

[0063] In the present invention, "configuration of an operation (e.g., sending an operation)" may refer to configuration information (e.g., information element, parameter) required for the operation and / or signaling of information indicating the execution of the operation. "Configuration of an information element (e.g., parameter)" may refer to signaling of an information element. In the present invention, "signal and / or channel" may refer to a signal, a channel, or both a signal and a channel, and "signal" may be used to mean "signal and / or channel".

[0064] The communication network to which the exemplary embodiment is applied is not limited to the communication network described below, and the exemplary embodiment can be applied to various communication networks (e.g., 4G communication network, 5G communication network and / or 6G communication network). Here, "communication network" can be used interchangeably with the term "communication system".

[0065] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0066] like Figure 1 As shown, the communication system 100 may include a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6. In addition, the communication system 100 may further include: a core network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (PDN gateway, P-GW), a mobility management entity (MME)). When the communication system 100 is a 5G communication (e.g., an NR system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc.

[0067] The plurality of communication nodes 110 to 130 may support communication protocols specified in the 3rd Generation Partnership Project (3GPP) standard (eg, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support the following technologies: code division multiple access (CDMA), wideband CDMA (WCDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiplexing (OFDM), filtered OFDM, cyclic prefix OFDM (CP-OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), orthogonal frequency division multiple access (OFDMA), single carrier FDMA (SC-FDMA), non-orthogonal multiple access (NOMA), generalized frequency division multiplexing (GFDM), filter bank multi-carrier (filter bank The communication nodes may include the following: multi-carrier (FBMC) technology, universal filtered multi-carrier (UFMC) technology, space division multiple access (SDMA) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0068] Figure 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0069] like Figure 2As shown, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network for performing communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. Each component included in the communication node 200 can communicate with each other when connected through a bus 270.

[0070] The processor 210 may execute a program stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which a method according to an embodiment of the present invention is executed. Each of the memory 220 and the storage device 260 may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0071] Reference again Figure 1 , the communication system 100 may include a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. The communication system 100 including the base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and the terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may be referred to as an "access network". Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell, and each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3 and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. In addition, the second terminal 130-2, the fourth terminal 130-4 and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. In addition, the fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5 and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. In addition, the first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1, and the sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

[0072] Here, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 may refer to a Node-B, an evolved Node-B (eNB), a gNB, an advanced base station (ABS), a high reliability base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multihop relay-base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (transmission point point (TP), transmission and reception point (TRP), etc.

[0073] Each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 may refer to user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability-mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, on-board unit (OBU), etc.

[0074] On the other hand, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can operate in the same frequency band or in different frequency bands. The multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can be connected to each other via an ideal backhaul or a non-ideal backhaul, and exchange information with each other via an ideal or non-ideal backhaul. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can be connected to the core network via an ideal or non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1 and 120-2 may transmit a signal received from the core network to a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6, and transmit a signal received from a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 to the core network.

[0075] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can support multiple-input multi-output (MIMO) transmission (for example, single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in unlicensed frequency bands, sidelink communication (for example, device-to-device (D2D) communication, proximity service (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operations corresponding to the following: operations of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and operations supported by the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 in a SU-MIMO manner, and the fourth terminal 130-4 may receive a signal from the second base station 110-2 in a SU-MIMO manner. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 in a MU-MIMO manner, and the fourth terminal 130-4 and the fifth terminal 130-5 may receive a signal from the second base station 110-2 in a MU-MIMO manner.

[0076] The first base station 110-1, the second base station 110-2 and the third base station 110-3 can send signals to the fourth terminal 130-4 in a CoMP transmission manner, and the fourth terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2 and the third base station 110-3 in a CoMP manner. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can exchange signals with the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 belonging to its cell coverage in a CA manner. Each of base stations 110-1, 110-2 and 110-3 can control the sidelink communication between the fourth terminal 130-4 and the fifth terminal 130-5, so the fourth terminal 130-4 and the fifth terminal 130-5 can perform sidelink communication under the control of the second base station 110-2 and the third base station 110-3, respectively.

[0077] On the other hand, a communication node that performs communication in a communication network may be configured as follows. Figure 3 The communication nodes shown may be Figure 2 A specific exemplary embodiment of a communication node is shown.

[0078] Figure 3 is a block diagram illustrating a first exemplary embodiment of a communication node performing communications.

[0079] like Figure 3 As shown, each of the first communication node 300a and the second communication node 300b can be a base station or a UE. The first communication node 300a can send a signal to the second communication node 300b. The transmission processor 311 included in the first communication node 300a can receive data (e.g., data unit) from the data source 310. The transmission processor 311 can receive control information from the controller 316. The control information may include at least one of system information, RRC configuration information (e.g., information configured by RRC signaling), MAC control information (e.g., MAC CE) or PHY control information (e.g., DCI, SCI).

[0080] The transmit processor 311 may generate data symbols by performing processing operations on data (e.g., encoding operations, symbol mapping operations, etc.). The transmit processor 311 may generate control symbols by performing processing operations on control information (e.g., encoding operations, symbol mapping operations, etc.). In addition, the transmit processor 311 may generate synchronization / reference symbols for synchronization signals and / or reference signals.

[0081] The Tx MIMO processor 312 may perform spatial processing operations (e.g., pre-coding operations) on data symbols, control symbols, and / or synchronization / reference symbols. The output (e.g., symbol stream) of the Tx MIMO processor 312 may be provided to a modulator (MOD) included in the transceivers 313a to 313t. The modulator may generate modulation symbols by performing processing operations on the symbol stream, and may generate signals by performing additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, up-conversion operations, etc.) on the modulation symbols. The signals generated by the modulators of the transceivers 313a to 313t may be transmitted through the antennas 314a to 314t.

[0082] The signal transmitted by the first communication node 300a may be received at the antenna 364a to the antenna 364r of the second communication node 300b. The signal received at the antenna 364a to the antenna 364r may be provided to a demodulator (DEMOD) included in the transceiver 363a to the transceiver 363r. The demodulator (DEMOD) may obtain samples by performing processing operations (e.g., filtering operations, amplification operations, down-conversion operations, digital conversion operations, etc.) on the signal. The demodulator may perform additional processing operations on the samples to obtain symbols. The MIMO detector 362 may perform MIMO detection operations on the symbols. The receiving processor 361 may perform processing operations (e.g., deinterleaving operations, decoding operations, etc.) on the symbols. The output of the receiving processor 361 may be provided to the data sink. 360 and controller 366. For example, data may be provided to data sink 360, and control information may be provided to controller 366.

[0083] On the other hand, the second communication node 300b can send a signal to the first communication node 300a. The transmission processor 368 included in the second communication node 300b can receive data (e.g., data unit) from the data source 367, and perform processing operations on the data to generate data symbols. The transmission processor 368 can receive control information from the controller 366, and perform processing operations on the control information to generate control symbols. In addition, the transmission processor 368 can generate reference symbols by performing processing operations on reference signals.

[0084] The Tx MIMO processor 369 may perform spatial processing operations (e.g., pre-coding operations) on data symbols, control symbols, and / or reference symbols. The output (e.g., symbol stream) of the Tx MIMO processor 369 may be provided to a modulator (MOD) included in the transceiver 363a to the transceiver 363t. The modulator may generate modulation symbols by performing processing operations on the symbol stream, and may generate signals by performing additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, up-conversion operations) on the modulation symbols. The signals generated by the modulators of the transceivers 363a to the transceivers 363t may be transmitted via the antennas 364a to the antennas 364t.

[0085] The signal transmitted by the second communication node 300b can be received at the antenna 314a to the antenna 314r of the first communication node 300a. The signal received at the antenna 314a to the antenna 314r can be provided to the demodulator (DEMOD) included in the transceiver 313a to the transceiver 313r. The demodulator can obtain samples by performing processing operations (e.g., filtering operations, amplification operations, down-conversion operations, digital conversion operations) on the signal. The demodulator can perform additional processing operations on the samples to obtain symbols. The MIMO detector 320 can perform MIMO detection operations on the symbols. The receiving processor 319 can perform processing operations (e.g., deinterleaving operations, decoding operations, etc.) on the symbols. The output of the receiving processor 319 can be provided to the data sink 318 and the controller 316. For example, data can be provided to the data sink 318, and control information can be provided to the controller 316.

[0086] Memory 315 and storage 365 may store data, control information and / or program codes. Scheduler 317 may perform scheduling operations for communications. Figure 3 The processors 311, 312, 319, 361, 368, 369 and the controllers 316 and 366 shown may be Figure 2 The processor 210 shown may be configured to execute the methods described in the present invention.

[0087] Figure 4a is a block diagram illustrating a first exemplary embodiment of a transmit path, Figure 4b is a block diagram illustrating a first exemplary implementation of a receive path.

[0088] like Figure 4a and Figure 4bAs shown, the transmission path 410 can be implemented in a communication node that transmits a signal, and the reception path 420 can be implemented in a communication node that receives a signal. The transmission path 410 may include: a channel coding and modulation block 411, a serial-to-parallel (S to P) block 512, an N-point inverse fast Fourier transform (N-point IFFT) block 413, a parallel-to-serial (P to S) block 414, a cyclic prefix (CP) adding block 415 and an up-converter (UC) 416. The reception path 420 may include a down-converter (DC) 421, a CP deletion block 422, an S to P block 423, an N-point FFT block 424, a P to S block 425 and a channel decoding and demodulation block 426. Here, N may be a natural number.

[0089] In the transmission path 410, the information bits may be input to the channel coding and modulation block 411. The channel coding and modulation block 411 may perform coding and decoding operations (e.g., low-density parity check (LDPC) coding and decoding operations, polar coding and decoding operations, etc.) and modulation operations (e.g., quadrature phase shift keying (OPSK), quadrature amplitude modulation (QAM), etc.) on the information bits. The output of the channel coding and modulation block 411 may be a modulation symbol sequence.

[0090] The S to P block 412 may convert the frequency domain modulation symbols into parallel symbol streams to generate N parallel symbol streams. N may be an IFFT size or an FFT size. The N-point IFFT block 413 may generate a time domain signal by performing an IFFT operation on the N parallel symbol streams. The P to S block 414 may convert the output (e.g., parallel signals) of the N-point IFFT block 413 into a serial signal to generate a serial signal.

[0091] The CP adding block 415 may insert the CP into the signal. The UC 416 may up-convert the frequency of the output of the CP adding block 415 to a radio frequency (RF) frequency. In addition, the output of the CP adding block 415 may be filtered in baseband before up-conversion.

[0092] The signal transmitted from the transmission path 410 may be input to the reception path 420. The operation in the reception path 420 may be the reverse operation of the operation in the transmission path 410. The DC 421 may down-convert the frequency of the received signal to the baseband frequency. The CP removal block 422 may remove the CP from the signal. The output of the CP removal block 422 may be a serial signal. The S to P block 423 may convert the serial signal into a parallel signal. The N-point FFT block 424 may generate N parallel signals by performing an FFT algorithm. The P to S block 425 may convert the parallel signal into a modulation symbol sequence. The channel decoding and demodulation block 426 may perform a demodulation operation on the modulation symbol, and may recover the data by performing a decoding operation on the result of the demodulation operation.

[0093] exist Figure 4a and Figure 4b In the present invention, discrete Fourier transform (DFT) and inverse DFT (IDFT) can be used to replace FFT and IFFT. Figure 4a and Figure 4b Each of the blocks (eg, components) in the embodiment may be implemented by at least one of hardware, software, or firmware. Figure 4a and Figure 4b Some blocks in the can be implemented by software, and other blocks can be implemented by hardware or a combination of hardware and software. Figure 4a and Figure 4b In the , a block can be subdivided into multiple blocks, multiple blocks can be integrated into one block, some blocks can be omitted, and blocks that support other functions can be added.

[0094] Figure 5 is a conceptual diagram illustrating a first exemplary embodiment of a system frame in a communication system.

[0095] like Figure 5 As shown, the time resources in the communication system can be divided on a frame basis. For example, the system frame of the communication system can be configured continuously in the time domain. The length of the system frame can be 10 milliseconds (ms). The system frame number (SFN) can be set to one of #0 to #1023. In this case, 1024 system frames can be repeated in the time domain of the communication system. For example, the SFN of the system frame after system frame #1023 can be #0.

[0096] One system frame may include two half frames. The length of the half frame may be 5 ms. The half frame located at the start area of ​​the system frame may be referred to as "half frame #0", and the half frame located at the end area of ​​the system frame may be referred to as "half frame #1". One system frame may include 10 subframes. The length of one subframe may be 1 ms. The 10 subframes within one system frame may be referred to as subframe #0-subframe #9.

[0097] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a subframe in a communication system.

[0098] like Figure 6 As shown, a subframe may include n time slots, where n may be a natural number. Accordingly, a subframe may consist of one or more time slots.

[0099] Figure 7 is a conceptual diagram illustrating a first exemplary embodiment of a time slot in a communication system.

[0100] like Figure 7 As shown, a time slot may include one or more symbols. For example, Figure 7 One slot shown in may include 14 symbols. The length of the slot may vary according to the number of symbols included in the slot and the length of the symbol. Alternatively, the length of the slot may vary according to a parameter set.

[0101] The parameter set applied to the physical signal and channel in the communication system can be variable. The parameter set can be adjusted to meet various technical requirements of the communication system. In a communication system applying OFDM waveform technology based on cyclic prefix (CP), the parameter set may include subcarrier spacing and CP length (or CP type). Table 1 may show a first exemplary embodiment of a method for configuring a parameter set of a communication system based on CP-OFDM. Depending on the frequency band in which the communication system operates, at least some of the parameter sets in Table 1 may be supported. In addition, the communication system may support parameter sets not listed in Table 1.

[0102] [Table 1]

[0103]

[0104] When the subcarrier spacing is 15kHz (e.g., μ=0), the length of the time slot may be 1ms. In this case, one system frame may include 10 time slots. When the subcarrier spacing is 30kHz (e.g., μ=1), the length of the time slot may be 0.5ms. In this case, one system frame may include 20 time slots.

[0105] When the subcarrier spacing is 60kHz (e.g., μ=2), the length of the time slot may be 0.25ms. In this case, one system frame may include 40 time slots. When the subcarrier spacing is 120kHz (e.g., μ=3), the length of the time slot may be 0.125ms. In this case, one system frame may include 80 time slots. When the subcarrier spacing is 240kHz (e.g., μ=4), the length of the time slot may be 0.0625ms. In this case, one system frame may include 160 time slots.

[0106] A symbol may be configured as a downlink (DL) symbol, a flexible (FL) symbol, or an uplink (UL) symbol. A time slot consisting only of DL symbols may be referred to as a "DL time slot", a time slot consisting only of FL symbols may be referred to as a "FL time slot", and a time slot consisting only of UL symbols may be referred to as a "UL time slot".

[0107] The slot format can be semi-statically configured by higher layer signaling (e.g., RRC signaling). Information indicating the semi-static slot format can be included in the system information, and the semi-static slot format can be configured to be cell-specific. In addition, the semi-static slot format can be further configured for each terminal by terminal-specific high-layer signaling (e.g., RRC signaling). The flexible symbols in the cell-specific slot format can be overwritten as downlink symbols or uplink symbols by terminal-specific high-layer signaling. In addition, the slot format can be dynamically indicated by physical layer signaling (e.g., a slot format indicator (SFI) included in the DCI). The semi-statically configured slot format can be overwritten by the dynamically indicated slot format. For example, the semi-statically configured flexible symbols can be overwritten by the SFI as downlink symbols or uplink symbols.

[0108] Reference signals may include a Channel State Information-Reference Signal (CSI-RS), a Sounding Reference Signal (SRS), a Demodulation-Reference Signal (DM-RS), and a Phase Tracking-Reference Signal (PT-RS). Channels may include a Physical Broadcast Channel (PBCH), a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Control Channel (PUCCH), a Physical Uplink Shared Channel (PUSCH), a Physical Sidelink Control Channel (PSCCH), and a Physical Sidelink Shared Channel (PSSCH). In the present invention, the control channel may refer to PDCCH, PUCCH or PSCCH, and the data channel may refer to PDSCH, PUSCH or PSSCH.

[0109] Figure 8 is a conceptual diagram illustrating a first exemplary implementation of time-frequency resources in a communication system.

[0110] like Figure 8 As shown, a resource consisting of one OFDM symbol on the time axis and one subcarrier on the frequency axis can be defined as a "resource element (RE)". A resource consisting of one OFDM symbol on the time axis and K subcarriers on the frequency axis can be defined as a "resource element group (REG)". A REG may include K REs. REG may be used as a basic unit for resource allocation in the frequency domain. K may be a natural number. For example, K may be 12. N may be a natural number. Figure 7 In the illustrated time slot, N may be 14. N OFDM symbols may be used as a basic unit for resource allocation in the time domain.

[0111] In the present invention, RB may refer to a common RB (CRB). Alternatively, RB may refer to a physical RB (PRB) or a virtual RB (VRB). In a communication system, CRB may refer to an RB that constitutes a set of continuous RBs (e.g., a common RB grid) based on a reference frequency (e.g., point A). A carrier and / or bandwidth part may be mapped to a common RB grid. That is, a carrier and / or bandwidth part may be configured with CRBs. An RB or CRB constituting a bandwidth part may be referred to as a PRB, and a CRB index may be appropriately converted to a PRB index within a bandwidth part.

[0112] Downlink data can be transmitted through PDSCH. The base station can send configuration information (e.g., scheduling information) of PDSCH to the terminal through PDCCH. The terminal can obtain the configuration information of PDSCH by receiving PDCCH (e.g., downlink control information (DownlinkControl Information, DCI)). For example, the configuration information of PDSCH may include the modulation coding scheme (MCS) used for sending / receiving PDSCH, the time resource information of PDSCH, the frequency resource information of PDSCH, and the feedback resource information of PDSCH. PDSCH may refer to the radio resources for sending and receiving downlink data. Alternatively, PDSCH may refer to the downlink data itself. PDCCH may refer to the radio resources for sending and receiving downlink control information (e.g., DCI). Alternatively, PDCCH may refer to the downlink control information itself.

[0113] The terminal may perform a monitoring operation on the PDCCH to receive the PDSCH sent from the base station. The base station may notify the terminal of configuration information for the PDCCH monitoring operation using a high-level message (e.g., a Radio Resource Control (RRC) message). The configuration information for the PDCCH monitoring operation may include control resource set (ControlResource Set, CORESET) information and search space information.

[0114] CORESET information may include PDCCH DMRS information, PDCCH precoding information, and PDCCH timing information, etc. PDCCH DMRS may be a DMRS used to demodulate PDCCH. PDCCH timing refers to an area where PDCCH may potentially exist, which means that it is an area where DCI can be transmitted. PDCCH timing may also be referred to as a PDCCH candidate. PDCCH timing information may include time resource information and frequency resource information for PDCCH timing. In the time domain, the length of the PDCCH timing may be indicated in symbols. In the frequency domain, the size of the PDCCH timing may be indicated in RB units (e.g., in PRB units or CRB units).

[0115] The search space information may include a CORESET identifier (ID) associated with the search space, a periodicity of PDCCH monitoring, and / or an offset of PDCCH monitoring. The periodicity and offset of PDCCH monitoring may each be indicated in units of time slots. In addition, the search space information may further include an index of a symbol at which the PDCCH monitoring operation starts.

[0116] The base station may configure a bandwidth part (Bandwidth Part, BWP) for downlink communication. The BWP may be configured differently for each terminal. The base station may notify the terminal of BWP configuration information using high-level signaling. High-level signaling may refer to a transmission operation of system information and / or a transmission operation of an RRC message. The number of BWPs configured for a single terminal may be one or more. The terminal may receive BWP configuration information from the base station and identify the configured BWP based on the received configuration information. When multiple BWPs are configured for downlink communication, the base station may activate one or more BWPs in the multiple BWPs. The base station may send configuration information of the activated BWP to the terminal using at least one of high-level signaling, a medium access control (MAC) control element (CE) or a DCI. The base station may perform downlink communication using the activated BWP. The terminal may identify the activated BWP by receiving configuration information from the base station and perform a downlink reception operation on the activated BWP.

[0117] On the other hand, TR 38.912 of the 3GPP specification specifies the multi-antenna scheme in 5G NR. For example, it defines beam determination, beam measurement, beam reporting, and beam scanning processes related to downlink (DL) and uplink (UL) as a set of L1 / L2 processes for beam management. The beam management process is described as being supported by one or more TRxPs.

[0118] On the other hand, as mentioned above, the 5G NR beam management process includes an initial beam establishment process, a beam adjustment process, and a beam recovery process. According to the current standard, during the initial beam establishment and beam adjustment process, beam scanning is used to sequentially change the beams one by one, measure the performance of the corresponding beams, and compare the measured performance to identify the best transmit or receive beam. However, in 6G terahertz communications that require highly directional beams due to high path loss, a larger number of beams need to be formed compared to 5G NR. Therefore, it is expected that the existing beam management scheme based on beam scanning will require significant time overhead. In addition, in high-frequency band communications, such as terahertz frequencies expected to be used for 6G, the expected channel coherence time is shorter. This makes it increasingly difficult to measure the signal quality of all candidate beams between the base station and the terminal using existing schemes. In the following description, the signal quality is described as reference signal received power (RSRP). However, other information as an indicator of channel quality, such as channel state information (CSI) or channel quality information (CQI), may also be used.

[0119] The present invention proposes a beam management process for utilizing an environment of a high frequency band such as a terahertz band in a future 6G communication system. In particular, the present invention proposes a beam management process utilizing a beam deflection phenomenon observed in the terahertz band.

[0120] The beam skew phenomenon refers to the difference in spatial direction observed for each subcarrier, which becomes more pronounced due to the high frequency and wide bandwidth of the terahertz band when beams are formed based on the center frequency using conventional methods.

[0121] The farther the subcarrier is from the center frequency, the more its signal direction deviates from the signal direction of the center frequency. Therefore, when such beam deflection is not compensated, even if beamforming is performed to transmit a beam in a single direction, the beam is formed in multiple directions according to the frequency band, making it difficult to achieve the desired received signal strength.

[0122] One solution derived from various studies for compensating for the beam skew phenomenon involves using a Time Delay Network (TDN) to apply different phase shifts to corresponding subcarriers so that the beams for all subcarriers are ultimately aligned in the same direction.

[0123] However, the present invention proposes a solution that does not completely compensate for the beam deflection phenomenon, and dynamically controls the TDN function based on multiple subcarriers to simultaneously form multiple beams in the desired direction. The base station and the terminal using the method proposed in the present invention can reduce the number of beam scans by simultaneously forming beams in multiple directions without sequentially scanning all candidate beams. In addition, the method according to the present invention can solve the significant time overhead problem that occurs when the sequential beam search method based on beam scanning is applied to terahertz communication.

[0124] In the present invention described below, a specific process required to perform beam management using the beam deflection phenomenon is provided. In addition, the parameters required therefor are also specified. As mentioned above, the 5G NR beam management process includes initial beam establishment, beam adjustment, and beam recovery processing. The present invention described below can be applied to all of these processes. Specifically, the present invention considers a scenario in which an initial beam establishment process has been performed in advance, and beam adjustment and beam recovery processes are subsequently performed. In addition, the present invention can also be applied to the initial beam establishment process. Accordingly, the present invention assumes a situation in which the base station and the terminal have already selected a wide beam for transmission and reception, and will describe a beam adjustment process for selecting the best beam from the wide beam selected during the initial beam establishment process, and a beam recovery process for selecting a new beam when beam misalignment occurs.

[0125] Figure 9a is a conceptual diagram illustrating a beam skew phenomenon when a base station transmits beams using multiple antennas.

[0126] like Figure 9a As shown, the base station 910 can use multiple antennas 911, 912, ..., 91M-1 and 91M in a specific frequency band f c For ease of description, Figure 9a A case where multiple antennas 911, 912, ..., 91M-1 and 91M are included in a single panel of a uniform linear array (ULA) is shown. As previously mentioned, compared to conventional systems, wireless communication systems are expected to utilize a significantly larger number of antennas when using wider frequency bands (e.g., unlicensed millimeter wave bands or terahertz bands). As the number of antennas increases, the distance between antennas within the antenna structure becomes larger, resulting in a larger difference in propagation delays between antennas.

[0127] In general, a time delay can result in a linear phase shift with respect to frequency. Beamforming can form a beam in a specific direction (the desired beam direction) by applying a specific phase shift. These phase shifts can vary with frequency. To elaborate, the phase shift for the desired beam direction can be expressed as a function of frequency.

[0128] As the frequency band allocated in wireless communication systems becomes wider, the difference between the frequency allocated to each subcarrier and the center frequency increases. In particular, in the terahertz band where communication is performed based on multiple subcarriers, the center frequency f c A beam transmitted at a frequency other than the frequency of the RF signal may be transmitted to propagate in an unintended direction. As described above, this phenomenon is defined as a beam deflection phenomenon.

[0129] Accordingly, if Figure 9a As shown, a desired direction at a frequency f can be formed. 3 (i.e., f c ) and the reference beam at frequency f based on the propagation delay 1 、f 2 、f 4 and f 5 As a result, beam deflection can occur in the spatial direction of subcarriers within the same frequency band, such as Figure 9a shown.

[0130] In order to fully deliver the expected information from the base station to the terminal and achieve the desired received signal strength, the direction of the deflected beam needs to be aligned with the center frequency f c Reference Figure 9a , we need to change f 1 、f 2 、f 4 and f 5 The deflected beam at f 3 =f c Hereinafter, the desired beam will be referred to as the reference beam.

[0131] In the case of the hybrid beamforming architecture used in 5G NR, it is not possible to resolve the beam skew phenomenon using a conventional hybrid beamforming structure because the analog phase shifter cannot produce different phase changes for each frequency.

[0132] In order to solve the beam deflection phenomenon, a TDN function has been proposed. The TDN function refers to a structure composed of multiple True Time Delay (TTD) elements located between a digital precoder and an analog phase shifter. Each TTD element constituting the TDN function has a specific delay value, and the TDN function composed of these TTD elements can generate different phase changes for each frequency.

[0133] Assume a scenario in which a base station transmits a signal based on a hardware structure including a digital precoder, an analog phase shifter, and a TDN function located therebetween, and a transmission signal through a wireless channel at an mth subcarrier may be expressed as shown in Equation 1 below.

[0134] [Equation 1]

[0135]

[0136] In Equation 1, H m represents the channel matrix, A represents the phase change caused by the analog phase shifter, represents the phase change caused by the TDN function, D m represents the digital precoder matrix, s m Represents the information to be sent, and n m Represents noise.

[0137] In this case, when the time delay value for each TTD element is expressed, It can be expressed as shown in Equation 2 below.

[0138] [Equation 2]

[0139]

[0140] In Equation 2, "blkdiag" refers to a block diagonal matrix whose diagonal elements are the values ​​within the brackets.

[0141] Comparing the phase changes caused by the analog phase shifters with the TDN function based on Equation 2, the phase changes caused by the analog phase shifters in Equation 1 are independent of the subcarrier index because they induce frequency-independent phase changes, so they are expressed as A.

[0142] In contrast, the phase change matrix of the TDN function It shows the time delay value of its main diagonal component according to the corresponding TTD element and the frequency f of the mth subcarrier m Both change. Therefore, it is clear that the TDN function generates frequency-dependent phase changes. By utilizing this characteristic of the TDN function, namely its ability to induce frequency-dependent phase changes, it is possible to compensate for the beam deflection phenomenon that occurs in the THz band.

[0143] In previous studies, the beam deflection phenomenon has been mainly compensated by configuring the TDN function so that the deflected beam is aligned with the direction of the reference beam, such as Figure 9b shown.

[0144] Figure 9b is a conceptual diagram showing a situation in which, when beams are transmitted using a plurality of antennas at a base station, a slanted beam is aligned with a direction of a reference beam.

[0145] like Figure 9b As shown, the base station 910 uses multiple antennas 911, 912, ..., 91M-1 and 91M to transmit signals in a specific frequency band f.c Send a signal in . Similar to Figure 9a , these multiple antennas are included in a single panel of ULA.

[0146] Compare Figure 9a and Figure 9b , Figure 9b Shows the frequency f of all subcarriers 1 、f 2 、f 3 、f 4 、f 5 and f 6 In contrast, at Figure 9a In the case of all subcarrier frequencies f 1 、f 2 、f 3 、f 4 、f 5 and f 6 The beam at f is based on the position of each subcarrier relative to the reference beam at f c =f 3 The frequencies at are skewed in different directions.

[0147] Previous research has mainly focused on Figure 9b In the method shown in , the TDN function is configured to align the deflected beam with the direction of the reference beam, thereby compensating for the beam deflection phenomenon.

[0148] The present invention proposes a method for dynamically controlling the TDN function to simultaneously form multiple beams in desired directions.

[0149] Fig.10 is a conceptual diagram showing a case where, when beams are transmitted using multiple antennas at a base station, a TDN function is dynamically controlled to simultaneously form multiple beams in desired directions.

[0150] like Fig.10 As shown, a base station 1010 and a plurality of antennas 1011, 1012, ..., 101M-1 and 101M are shown included in a single panel of a ULA. Fig.10 and Figure 9a For comparison, the difference is Fig.10 All beams in f 1 、f 2 、f 3 、f 4 and f 5 The deflected beam at the

[0151] In the present invention, the base station 1010 does not fully compensate for the beam skew phenomenon. Instead, it dynamically controls the TDN function to form beams so that those beams generated across multiple subcarriers are simultaneously pointed in different directions. Fig.10 In the example in FIG. 1 , the base station 1010 can configure a range for beam scanning, which is called an angle search space 1020. Based on predefined conditions, it can simultaneously transmit multiple beams in different directions within the angle search space 1020 using multiple subcarriers.

[0152] In the following description, the present invention will describe a process for configuring a reference signal as a channel state information reference signal (CSI-RS) to use the beam deflection phenomenon for beam adjustment and beam recovery processing, and for determining the best transmit and receive beams. Although other types of signals besides CSI-RS can be used as reference signals, for ease of description, the present invention will describe the case of using CSI-RS. In addition, the parameters used in the process will be described. The following description mainly assumes a downlink environment, but can be extended to an uplink environment, which will be apparent to those skilled in the art.

[0153] In addition, the present invention considers the scenario where the initial beam establishment process has been performed. However, the method proposed in the present invention can be extended to simultaneously form multiple beams during the process of selecting a wide beam by using a combination of SSB time index and RACH opportunity in the base station and the terminal to achieve low-latency initial beam establishment process.

[0154] [Low-latency beam steering using beam skewing]

[0155] In the present invention, during the initial beam establishment process, the base station and the terminal use a combination of the SSB time index and the RACH opportunity to determine the approximate beam direction. Based on the beam direction determined between the base station and the terminal, a beam adjustment process can be performed to select the best beam through a more refined beamforming process.

[0156] The beam adjustment process in the present invention can be divided into two stages.

[0157] In the first stage, the terminal uses a fixed beam. The terminal uses the fixed beam to evaluate the performance of each candidate beam belonging to the candidate beam group of the base station. Based on the performance evaluation, the terminal can select the best beam, which can be one of the transmission beams of the base station.

[0158] In the second stage, the beam of the base station may be fixed. The terminal may evaluate the performance of each candidate beam belonging to its own candidate beam group relative to the fixed beam of the base station. Based on the performance evaluation, the terminal may select the best beam, which may be one of the receiving beams of the terminal.

[0159] The first stage will be described in more detail.

[0160] The first stage may be performed during the initial beam establishment process. In the initial beam establishment process, the terminal may fix its receive beam to a wide beam. In the first stage, the base station may send a reference signal (e.g., CSI-RS) through a candidate beam. The terminal may measure the reference signal sent through the corresponding candidate beam and report the measurement result to the base station. Therefore, the base station may select the best transmit beam based on the measurement result reported by the terminal.

[0161] In the second stage, the transmission beam of the base station can be fixed to the beam selected in the first stage. The terminal can use multiple reception beams to measure the reference signal (e.g., CSI-RS) transmitted by the best transmission beam of the base station. Based on the measurement results, the terminal can select the best reception beam.

[0162] In the first stage in which the base station forms a transmit beam, and in the second stage in which the terminal forms a receive beam, the conventional method defined in the 5GNR standard involves sequentially changing the beams one by one, that is, performing beam scanning for measurement. In contrast, the present invention utilizes the beam deflection phenomenon to simultaneously form multiple beams in different directions. In other words, by utilizing the beam deflection phenomenon, different subcarriers can undergo beam deflection in changing directions, enabling them to form multiple beams instead of a single beam. Therefore, the base station and the terminal can utilize the beam deflection phenomenon to simultaneously measure the performance of beams formed in multiple directions, thereby significantly reducing time overhead.

[0163] Fig.11 This is a conceptual diagram showing a case where a base station allocates transmission beam resources using beam deflection.

[0164] like Fig.11 As shown, base station 1101 is shown as including multiple antennas within a single panel 1110 of a ULA. Fig.11 and Fig.10 The difference is that the base station is at f 1 、f 2 、f 3 、f 4 and f 5 A deflected beam is configured at t 1 ,t 2 and t 3 Send in different directions. Fig.10As shown, the base station 1101 according to the present invention does not completely compensate for the beam deflection phenomenon. Instead, the base station 1101 can dynamically control the TDN function to form a beam so that multiple subcarriers are deflected, thereby enabling beams to be formed in multiple directions at the same time. Fig.11 In the embodiment, a range for beam scanning, called an angle search space 1120, may be configured with a predefined angle θ. The base station 1101 may simultaneously transmit multiple beams pointing to different directions via multiple subcarriers within the angle search space 1120. Here, it may happen that the base station 1101 cannot cover the entire angle search space 1120 in a single transmission of a slanted beam. In this case, the base station 1101 may transmit the slanted beam multiple times to cover the entire angle search space 1120. For example, the base station 1101 may transmit the slanted beam multiple times at time t 1 In f 1 、f 2 、f 3 、f 4 and f 5 Send a skewed beam at time t 2 In f 1 、f 2 、f 3 、f 4 and f 5 The deflected beam is sent at time t 3 In f 1 、f 2 、f 3 、f 4 and f 5 A skewed beam is sent at each location to cover the entire angular search space 1120.

[0165] exist Fig.11 In the angular search space 1120, the predefined angle θ may correspond to the range over which beam scanning is performed during the beam adjustment process. 1 f 1 ) to the bottom position (at t 3 f 5 ) can correspond to the candidate beams of the base station (i.e., BS Beam #1 to BS Beam #15). Fig.11 A case is shown where candidate beams are transmitted in three sectors, where each transmission utilizes a different five frequencies to transmit the beam as a skewed beam.

[0166] At time t 1 , the base station 1101 can dynamically control the TDN function to utilize the five frequency resources f 1 to f 5 Generate a skewed beam. In other words, Figure 9a As stated, at time t1 , the base station 1101 can control the TDN function so that other beams (for example, in f 1 Beam #1 at f 2 Beam #2 at f 4 Beam #4 at f 5 Beam #5 at ) is obtained by using the beam corresponding to the center frequency f c The third subcarrier f 3 The formed central beam #3 spreads outward. The base station 1101 can 2 and time t 3 The TDN function is controlled in the same way.

[0167] In this case, if Fig.11 As shown, in order to transmit beams symmetrically around a specific beam, the frequency resource intervals corresponding to the corresponding beams need to be consistent. In other words, assuming that the frequency is from f 1 Increase to f 5 , in order to Fig.11 The transmit beam shown, f 2 With f 1 The frequency interval between 3 With f 2 The frequency interval between 4 With f 3 The frequency interval between 5 With f 4 Therefore, the frequency resources used for CSI-RS transmission need to have equal intervals between adjacent frequencies.

[0168] If the transmission band is configured differently, then at time t 1 The transmitted frequency band {f 1 ,…,f 5}, at time t 2 The transmitted frequency band {f 6 ,…,f 10} and at time t 3 The transmitted frequency band {f 11 ,…,f 15} need to be configured so that the beam angles of the candidate beams are equally spaced, such as Fig.11 In this case, the main lobes of the candidate beams need to be configured not to overlap with each other, and the TDN function needs to be configured so that all angles within the angle search space 1120 transmitted at a single time belong to a specific main lobe.

[0169] On the other hand, Fig.11 The method shown is compared with a conventional method.

[0170] From the perspective of time overhead, the beam management processing in 5G NR is compared with Fig.11 In the 5G NR beam management process, the base station sends beams one by one to evaluate the performance of each candidate beam, performing a total of 15 beam scans. In contrast, using Fig.11 The beam deflection phenomenon according to the present invention is shown, where beams are sent simultaneously in five different directions, and the number of beam scans can be reduced to three. Therefore, this process can be considered as a low-latency beam adjustment method suitable for the terahertz frequency band.

[0171] Tables 2 to 4 below show the process in which the base station 1101 allocates frequency and time resources to its candidate beams during the beam adjustment process and sends allocation information to the terminal. Fig.11 shown.

[0172] [Table 2]

[0173]

[0174] [Table 3]

[0175]

[0176] [Table 4]

[0177]

[0178]

[0179] Table 2 shows the beam index at time t 1 is assigned to the frequency f 1 、f 2 、f 3 、f 4 and f 5 Table 3 shows the beam index at time t. 2 is assigned to the frequency f 1 、f 2 、f 3 、f 4 and f 5 Table 4 shows the beam index at time t. 3 is assigned to the frequency f 1 、f 2 、f 3 、f 4 and f 5 A similar situation is presented for a skewed beam at .

[0180] Tables 2 to 4 may be tables corresponding to examples of utilizing a skewed beam within the angle search space 1120 during the initial beam establishment process, such as Fig.11 As shown. In the angle search space 1120 at time t 1 The total beam transmitted may be a wide beam, and each deflected beam may be a narrow beam. Similarly, within the angular search space 1120 at time t 2 and t 3 The total beam transmitted may be a wide beam, and each deflected beam may be a narrow beam. Tables 2 to 4 assume that the use of Fig.11 The number of candidate beams for the skewed beams shown is determined to be a total of 15 scenarios. Fig.11 Tables 2 to 4 show examples in which 15 candidate beams are transmitted in three groups over a total of 3 transmissions, each group including 5 beams.

[0181] Fig.11 Tables 2 to 4 are only examples, and the present invention is not limited thereto. In other words, if the base station 1101 has more frequency resources available for transmission to the terminal, and the entire angle search space 1120 can be covered in a single transmission according to the beam deflection of the frequency resources, all 15 candidate beams can be transmitted in a single transmission. As another example, even when there are sufficient frequency resources, if the beam deflection of the frequency resources cannot cover the entire angle search space 1120, or if the frequency resources are less than Fig.11 If the frequency resources shown in , a larger number of transmissions may be required.

[0182] As shown in Tables 2 to 4, the base station 1101 may need to allocate frequency and time resources to corresponding candidate beams to evaluate the performance of the candidate beams for beam adjustment.

[0183] In addition, the base station 1101 may need to allocate frequency and time resources for sending a total of 15 candidate beams, and send information about the allocated frequency and time resources to the terminal. The frequency and time resources allocated by the base station 1101 may be notified by various types of messages or signals. For example, such a message or signal may utilize downlink control information (DCI), medium access control-control element (MAC-CE), radio resource control (RRC) reconfiguration, or one of the RRC signaling newly defined according to the present invention.

[0184] The terminal can receive the information shown in Tables 2 to 4 from the base station 1101, and perform CSI-RS measurement result reporting based on the following description using the allocated frequency and time resources. However, the delivery of the information in Tables 2 to 4 can be flexibly performed according to the situation and necessity as the base station 1101 performs the preparation processing required for CSI-RS transmission to the terminal, such as when the terminal requests or for beam management of the base station.

[0185] On the other hand, the terminal can receive the CSI-RS for the corresponding beam through the beam mapped as shown in Table 5 based on the frequency and time resources notified by the base station 1101. In Tables 2 to 4, the corresponding beam is identified using an index such as beam #1, beam #2, ..., and beam #15. However, in an actual wireless communication system, the beam index can be expressed in a binary format. An example of such a beam index is shown in Table 5 below.

[0186] [Table 5]

[0187] Candidate beams for base stations Beam Index Candidate beams for base stations Beam Index BS beam #1 0000 BS beam #9 1000 BS beam #2 0001 BS beam #10 1001 BS beam #3 0010 BS beam #11 1010 BS beam #4 0011 BS beam #12 1011 BS beam #5 0100 BS beam #13 1100 BS beam #6 0101 BS beam #14 1101 BS beam #7 0110 BS beam #15 1110 BS beam #8 0111

[0188] During the beam adjustment process, the base station 1101 may map the beam index illustrated in Table 5 to the candidate beam, and transmit the CSI-RS using the resources (time and frequency resources) illustrated in Tables 2 to 4 together with the beam index.

[0189] When beam deflection is used, the beam direction changes according to the frequency band assigned to the beam. Therefore, the base station 1101 may need to deliver information about the frequency and time resources allocated to implement the candidate beam to the terminal to ensure accurate performance measurement of the candidate beam. Fig.11 As shown, in order to send the candidate beams, the base station 1101 may need to inform the terminal in advance of the frequency and time resources allocated for the CSI-RS of the corresponding beam, as described in Tables 2 to 4. Accordingly, the base station 1101 can share with the terminal information about its candidate beams used in the beam adjustment process by notifying the terminal in advance in a format such as the example in Table 5 by using the message or signal as described above.

[0190] Assuming that the total number of candidate beams of the base station 1101 used in the beam adjustment process is n, the bit length of the beam index can be determined using a ceiling function (ceil) to distinguish each candidate beam. For example, a ceiling function as shown in the following equation 3 can be used.

[0191] [Equation 3]

[0192] ceil(log 2 n)

[0193] Equation 3 determines the bit length of the beam index. When n is 1, 1 bit may be allocated. Based on the determined bit length, beams may be identified in a binary manner starting from the first beam.

[0194] When 15 beams are used based on Equation 3, 4 bits are required, and each beam may be assigned an index as shown in Table 5. Accordingly, the base station 1101 may transmit the CSI-RS together with the beam index when transmitting the CSI-RS. Then, the terminal may identify the beam that transmits the CSI-RS received from the base station 1101 using the beam index.

[0195] In addition, the terminal can measure the performance of the received CSI-RS and send the beam index together when reporting the measurement result to the base station 1101. Accordingly, when the base station 1101 receives the RSRP value of the CSI-RS, the base station 1101 can identify each beam by the beam index.

[0196] During the beam adjustment process of the base station 1101, the terminal may need to fix the receiving beam to the beam selected during the initial beam establishment process. Therefore, the terminal may need to configure the TDN function to fully compensate for the beam deflection phenomenon, such as Fig.10 Then, the terminal may need to form a beam in one direction through the configured TDN function to receive the CSI-RS.

[0197] On the other hand, the beam index has been used to describe the mapping of frequency and time resources to the beam, as exemplified in Table 5. However, since the frequency and time information have been determined, the beam can also be identified only by relying on the frequency and time information without using the beam index. Therefore, the beam index exemplified in Table 5 may not be used. In other words, only the base station 1101 may know the index in Table 5, or only the base station 1101 may know the information in Tables 2 to 4. In this case, the terminal may send the RS index to the base station 1101 when reporting the CSI-RS measurement results, such as in the 5G NR system. In this case, the base station 1101 may utilize Table 5 in the process of identifying the beam corresponding to the RS index. For ease of description, the following description assumes the use of the beam index in Table 5.

[0198] Through the above processing, the terminal can receive the CSI-RS through the frequency and time resources notified by the base station 1101 for the corresponding beam index exemplified in Table 5. The terminal can measure the CSI-RS sent by the base station 1101 for multiple beams, and report the RSRP value of the CSI-RS to the base station together with the beam index. An example of the RSRP value of the CSI-RS reported by the terminal to the base station can be as shown in Table 6 below.

[0199] [Table 6]

[0200]

[0201] The terminal may measure the RSRP of each received CSI-RS from the candidate beams transmitted by the base station 1101 and transmit the result to the base station 1101, as illustrated in Table 6.

[0202] Table 6 provides an example in which base station 1101 has a total of 15 candidate beams. The terminal can measure the performance of the CSI-RS transmitted by base station 1101 through the 15 candidate beams, and report the measurement result together with the beam index to base station 1101. In Table 6, the beam index corresponds to the beam index of each candidate beam of base station 1101 described in Table 5, and the RSRP value represents the RSRP for each candidate beam.

[0203] The terminal may report the RSRP value of the CSI-RS to the base station through a CSI reporting process, and transmit information about a beam index associated with the CSI-RS to the base station through uplink control information (UCI).

[0204] The reporting process of the RSRP of the CSI-RS sent by the candidate beam of the base station may involve the base station transmitting information about the performance reporting instructions of its candidate beams to the terminal through the UEInformationRequest in the RRC signaling. If the UEInformationRequest in the RRC signaling is configured with the performance reporting instructions for the candidate beams of the base station 1101, the terminal can send information about the RSRP of the candidate beams of the base station 1101. In addition, the information about the performance reporting instructions of the candidate beams of the base station can also be sent through the SIB designed to apply the present invention or the newly defined RRC signaling. The terminal can respond to the reporting instruction using a measurement report or UE auxiliary information. As another example, if new RRC signaling is defined for reporting according to the present invention, the newly defined RRC signaling can also be used.

[0205] Based on the above description, the base station 1101 can identify the beam index of the beam with the best performance among multiple candidate beams based on the RSRP feedback from the terminal. In addition, the base station 1101 can determine the transmission beam using the beam index of the beam with the best performance obtained during the beam adjustment process.

[0206] As exemplified in Table 6, since the RSRP of BS beam #7 corresponding to beam index '0110' has the highest value, base station 1101 may select BS beam #7 as the best beam.

[0207] Through the above-mentioned process, in other words, through the beam adjustment process described with reference to Tables 2 to 6, the base station 1101 can select the best beam among its candidate beams belonging to its beam candidate group.

[0208] Hereinafter, a process will be described in which, in the case where base station 1101 has fixed its transmit beam to BS beam #7, the terminal measures the performance of candidate beams within its beam candidate group and identifies the best receive beam.

[0209] The terminal may have a beam candidate group as illustrated in Table 7 below.

[0210] [Table 7]

[0211]

[0212] As described above, after the beam adjustment process in the base station 1101, the terminal may need to configure its beam candidate group to perform the beam adjustment process. Accordingly, the terminal may need to inform the base station 1101 of the number of its candidate beams.

[0213] In Table 7, each candidate beam belonging to the beam candidate group of the terminal may have a narrower beam width than the reception beam selected during the initial beam establishment process. The candidate beams of the terminal shown in Table 7 may be interpreted as narrower beams into which the reception beam established by the initial beam establishment process is subdivided.

[0214] In order to evaluate the CSI-RS reception performance of its candidate beams during the beam adjustment process, the terminal may notify the base station 1101 of the number of its candidate beams. For example, the terminal may use UCI, UE assistance information, or UE performance information to notify the base station of the number of its candidate beams. Alternatively, if the new RRC signaling according to the present invention is defined to send information about the number of candidate beams, the terminal may use the corresponding RRC signaling to send information about the number of its candidate beams to the base station 1101.

[0215] Upon receiving information about the number of candidate beams from the terminal, the base station 1101 may allocate CSI-RS frequency and time resources corresponding to the number of candidate beams of the terminal, and send CSI-RS to the terminal using the allocated resources.

[0216] When the base station 1101 transmits CSI-RS during the beam adjustment process at the terminal, the base station 1101 can use the parameter "ENUMERATED{on,off}" of the "repetition" in the NZP-CSI-ResourceSet IE of the RRC reconfiguration message, as defined in the 5GNR standard. In other words, by sending the number of repetitions of the configured beam using "ENUMERATED{on,off}" in the NZP-CSI-ResourceSet IE of the RRC reconfiguration message to the terminal, the base station 1101 can notify the terminal that the transmission beam currently used by the base station 1101 is fixed. In this case, the base station 1101 can determine the number of repetitions based on the number of candidate beams notified from the terminal.

[0217] In Table 7, an example is provided in which the terminal has a total of six candidate beams. Accordingly, the angular search space of the terminal can be composed of six narrow beams. In other words, during the receiving beam adjustment process of the terminal, there may be six narrow beams within the range in which the terminal performs beam scanning. Under the condition that the transmit beam of the base station is fixed to BS beam #7, the terminal can measure the performance of beams ranging from UE beam #1 to UE beam #6, and select the best receiving beam based on the results.

[0218] In order to perform receive beam adjustment at the terminal, the base station 1101 may need to allocate time and frequency resources to the terminal to measure the performance of its receive beam. Table 8 provides an example of time and frequency resources allocated by the base station 1101 for receive beam adjustment of the terminal.

[0219] [Table 8]

[0220]

[0221] When the terminal has a total of six candidate beams as described in reference Table 6, Table 8 provides the 4 and t 5 An example of frequency resource information to which the CSI-RS is allocated is used to measure the performance of a reception beam of a terminal.

[0222] At time t 4 , base station 1101 can allocate frequency f′ 1 , f′ 2 and f′ 3 To send CSI-RS for measuring the receiving beam performance of the terminal. Similarly, at time t 5 , the base station can allocate frequency f′ 1 , f′ 2 and f′ 3 To send CSI-RS.

[0223] Using UE beam #1, UE beam #2 and UE beam #3, the terminal can pass the frequency f′ 1 , f′ 2 and f′ 3 Measured at time t 4 Similarly, using UE beam #4, UE beam #5, and UE beam #6, the terminal can transmit CSI-RS through frequency f′ 1 , f′ 2 and f′ 3 Measured at time t 5 The transmitted CSI-RS.

[0224] As shown in Table 8, during the measurement of the receiving beam performance of the terminal, the transmitting beam of the base station 1101 can remain fixed to BS beam #7. Therefore, the base station 1101 can control the TDN function to send CSI-RS to the terminal using a beam that fully compensates for the beam deflection phenomenon, such as Figure 9b shown.

[0225] On the other hand, the terminal can receive CSI-RS through multiple receive beams at a specific time. In other words, the terminal can use multiple receive beams to receive the beam that transmits CSI-RS without configuring the TDN function to fully compensate for the beam deflection phenomenon. Configuring the TDN function to fully compensate for the beam deflection phenomenon can be used Fig.11 For example, as described in Fig.11 In the transmit beam alignment process of the base station described in , the TDN function can be controlled to align the deflected beam toward a direction near the reference beam, thereby forming multiple receive beams at the same time. In Table 8, the base station 1101 can 4 Through three frequency resources f′ 1 to f′ 3 (ie, three subcarriers) transmit beams. Therefore, according to Table 8, the terminal can use the beam deflection phenomenon to simultaneously form three beams in different directions and receive signals.

[0226] Table 8 provides an example in which the base station 1101 transmits CSI-RS in two rounds, three beams at a time, so that the terminal can measure the performance of a total of six reception beams. However, this is only an example, and the present invention is not limited to the example of Table 8.

[0227] The above method will be described in comparison with 5G NR.

[0228] From the perspective of time overhead, in 5G NR beam management, the terminal needs to perform six rounds of beam scanning to evaluate the performance of each candidate beam by receiving CSI-RS through one receiving beam at a time. In contrast, based on the beam deflection phenomenon in the present invention, the terminal can simultaneously form beams in different directions, thereby reducing the number of beam scanning rounds to two. Therefore, this can achieve low-latency beam adjustment processing suitable for wireless communication systems in the terahertz band.

[0229] By referring to the process described in Table 8, the terminal can measure the performance of its candidate beams during the beam adjustment process, as defined in Table 7.

[0230] In the process described with reference to Table 8, the terminal may measure RSRP values ​​for its candidate beams, as illustrated in Table 9.

[0231] [Table 9]

[0232] Candidate beams for the terminal RSRP Value UE beam #1 RSRP_77 UE beam #2 RSRP_50 UE beam #3 RSRP_65 UE beam #4 RSRP_98 UE beam #5 RSRP_106 UE beam #6 RSRP_84

[0233] Table 9 provides an example of the result of the terminal using each of its candidate beams to measure the RSRP of the CSI-RS transmitted by the base station 1101. As shown in Table 9, the terminal can receive the CSI-RS for each of its candidate beams and measure the RSRP of the CSI-RS. Based on the measured RSRP value, the terminal can select the best reception beam.

[0234] Table 9 provides an example in which, assuming that the terminal has a total of six candidate beams, the terminal measures the performance of its reception beam for the CSI-RS transmitted by the base station 1101. In Table 9, the candidate beam of the terminal refers to each candidate beam within the beam candidate group defined in Table 7, and the RSRP value represents the RSRP of the measured CSI-RS transmitted by the base station 1101 using each candidate beam.

[0235] The base station 1101 may receive information about the number of reception beams of the terminal and transmit the CSI-RS one or more times to ensure that the terminal can receive the CSI-RS through its reception beam.

[0236] After receiving the CSI-RS through its candidate beams, the terminal may measure the RSRP of the CSI-RS transmitted by the base station 1101 for each candidate beam, and determine the best reception beam based on the measurement result.

[0237] According to the example in Table 9, since the RSRP of UE beam #5 is the highest, the terminal can select UE beam #5 as the best reception beam during the beam adjustment process.

[0238] When the operations described in Tables 7 to 9 are collectively described, these operations can be understood as a process in which the terminal selects the best beam from the candidate beams in its beam candidate group during the beam adjustment process. In other words, the terminal can measure the performance of the candidate beams for receiving the fixed beam transmitted by the base station 1101 using the CSI-RS, and determine the best reception beam based on the measured performance.

[0239] The above description has covered the low-latency beam adjustment method using beam deflection. In other words, the operations described with reference to Tables 2 to 9 may correspond to the process of the base station 1101 and the terminal selecting a narrower beam after the initial beam is established. Specifically, Tables 2 to 6 relate to the process for the base station to select the best transmit beam by beam scanning, and Tables 7 to 9 relate to the process for the terminal to select the best receive beam by beam scanning.

[0240] In addition, according to the present invention, by appropriately controlling the TDN function in the high frequency band where the beam deflection phenomenon occurs, multiple beams can be formed simultaneously in the desired direction. In addition, the performance of multiple beams can be measured simultaneously. Therefore, during beam adjustment, the method according to the present invention can be considered to be different from the sequential beam search scheme used in 5G NR.

[0241] [Low-latency beam recovery using beam deflection]

[0242] Already referenced Fig.11 Tables 2 to 9 describe the beam adjustment process for identifying the best beam from the transmit beam or receive beam formed based on the beam deflection phenomenon. Through the above processing, the best beam can be found without performing a beam scanning process separately for the corresponding candidate beams. This makes it possible to meet the high-level low-latency communication requirements required by the 6G communication system.

[0243] Hereinafter, a beam recovery process considering the delay requirement of the terminal will be described in the case where the channel state between the base station and the terminal changes, making it difficult to continue to use the previously identified best beam obtained through the previous process.

[0244] If a beam failure occurs in the communication link between the base station and the terminal, the terminal may send a beam failure recovery request message to the base station. Upon receiving the beam failure recovery request message, the base station may determine the number of beam scans to be performed during the beam recovery process based on the delay requirement of the terminal. In this case, the delay requirement may be determined based on the data served to the terminal. As another example, the delay requirement may be included in the beam failure recovery request message pre-received from the terminal or pre-configured based on the level of the terminal. In addition, the number of beam scans may be determined based on the beam direction to which the CSI-RS is transmitted within the angle search space.

[0245] A beam failure condition refers to a situation where the beam failure instance (BFI) for a communication link established between a terminal and a base station exceeds the maximum allowed count. When a beam failure occurs, a beam recovery process needs to be performed. The terminal and / or the base station may be equipped with a beam failure instance counter (BFI_COUNTER) to detect beam failures. When the number of beam failure instances exceeds or equals a predefined maximum count value (i.e., BFI_COUNTER ≥ BeamFailureInstanceMaxCount), the BFI_COUNTER declares a beam failure. Here, BFI refers to a situation where the block error rate (BLER) exceeds a certain threshold. Each time a BFI occurs, the value of the BFI_COUNTER increases by 1. If the BFI_COUNTER does not increase during a predefined time period after being incremented by 1, the BFI_COUNTER may be reset to zero and interpreted as no further BFI occurring.

[0246] The beam failure recovery request information can be sent from the terminal to the base station via the BeamFailureRecoveryConfig including information such as rach-ConfigBFR, rsrp-ThresholdSSB, and candidateBeamRSList of RRC signaling. Upon receiving the beam failure recovery request information, the base station can determine the number of beam scans to be performed during the beam recovery process based on the waiting time requirement value requested by the terminal.

[0247] Table 10 illustrates the determination of the number of beam scans and beam directions within the angle search space based on the waiting time requirement value of the terminal during beam recovery.

[0248] [Table 10]

[0249]

[0250] In Table 10, it is assumed that LR UE is the waiting time requirement of the terminal, and T is the time required to perform a single beam scanning process, giving the determination of the corresponding LR UE Example of the number of beam scans that can be performed within a given time period.

[0251] As shown in Table 10, when the waiting time requirement value of the terminal is larger, more time resources can be allocated to the beam recovery process. Therefore, the base station can perform more beam scans. Performing more beam scans increases the number of measurable angles in the angle search space.

[0252] It will be described in Fig.11During the beam adjustment process in the environment described in , it is assumed that up to five frequency resources are available for simultaneous CSI-RS transmission.

[0253] For example, when considering the terminal's waiting time requirement LR UE If the time required to perform two beam scanning processes is less than 2T, since the base station can only perform one beam scanning, if the entire angle search space range is from θ 1 to θ 2 , five frequency resources need to be used to cover the entire angle space. Accordingly, the entire angle search space 1120 needs to be divided into five sections, as shown in the following equation 4.

[0254] [Equation 4]

[0255]

[0256] As shown in Equation 4, the entire angular search space can be divided into five angular segments, and the beam can be configured to be transmitted at the midpoint of each divided angular segment. This can correspond to the first case (LR UE <2T).

[0257] As another example, when the waiting time requirement of the terminal satisfies 3T≤LR UE <4T, the number of possible beam scans may be three. Accordingly, as in the last case of Table 10, the beam direction may be measured over three scans.

[0258] Subsequently, the base station may perform a beam recovery process on the beam direction within the angle search space 1120 determined based on the waiting time requirement of the terminal, as shown in Table 10. During the beam recovery process, the base station 1101 may transmit the CSI-RS using each candidate beam group pointing to the corresponding angle. The terminal may then measure the RSRP of the CSI-RS received through the candidate beam. The terminal may feed back the measured RSRP to the base station. Based on the RSRP fed back by the terminal, the base station 1101 may reselect the transmit beam.

[0259] As described above with reference to Table 10, base station 1101 may determine the number of possible transmit beam scans based on the latency requirement of the terminal.Base station 1101 may then determine the beam direction within angle search space 1120 of the transmit beam based on the determination.

[0260] The base station can determine the number of beam scans based on the method defined in the 5G NR standard. The number of beam scans can be configured differently according to the waiting time requirements of the terminal. Once the number of beam scans is determined, the angle search space can be configured, and the beam can be sent according to the determined number of beam scans, as shown in Table 10.

[0261] The above-mentioned beam recovery process relates to the transmit beam recovery process. However, the present invention can also be extended to also be applied to the receive beam recovery process.

[0262] As described with reference to Table 10, the base station 1101 may determine a candidate beam group to be used for beam recovery based on the waiting time requirement of the terminal. Once the base station 1101 determines the candidate beam group to be used, the base station 1101 may need to allocate frequency and time resources for CSI-RS transmission. Table 11 illustrates a case where the base station 1101 allocates frequency and time resources for CSI-RS transmission.

[0263] [Table 11]

[0264]

[0265] Table 11 shows a modified form of information about the BS restoring beam compared to the previously described Table 5. In addition, the beam index may be configured as described in Table 5, and the CSI-RS resource allocation information may be configured as described in Tables 2 to 4.

[0266] Table 11 corresponds to the waiting time requirement LR of the terminal in Table 10 UE This results in a situation where the possible beam scan count is 1. The base station 1101 can determine a candidate beam group to be used for beam recovery, thereby focusing on the best transmission beam used during the beam adjustment process. In addition, as described in Table 10, the number of beams included in the candidate beam group for the beam recovery process can vary according to the number of possible beam scans and the number of beams that can be transmitted simultaneously.

[0267] In other words, Table 11 assumes a situation where a beam failure occurs to the best transmit beam (BS beam #7) identified during the beam adjustment process at the base station. In this example, the terminal's waiting time requirement LR UE This corresponds to the first case in Table 10, where the number of possible beam scans at base station 1101 is 1. Accordingly, the beam candidate group for beam recovery processing within angle search space 1120 may be newly configured from BS recovery beam #1 to BS recovery beam #5.

[0268] Therefore, the base station 1101 can allocate time resources t to the candidate beams from BS recovery beam #1 to BS recovery beam #5. 6 and frequency resource f″ 1 to f″ 5 , and uses the allocated resources to send CSI-RS to the terminal through these beams.

[0269] If the terminal's waiting time requirement satisfies the second case (i.e., 2T ≤ LRUE <3T), the number of possible beam scans at base station 1101 may be 2. In addition, base station 1101 is able to use 10 candidate beams. Candidate beams (i.e., BS recovery beam #1 to BS recovery beam #10) may be newly configured within the angle search space shown in Table 10. Base station 1101 may transmit CSI-RS through these candidate beams, wherein the corresponding candidate beams are allocated frequency and time resources as described above.

[0270] In Table 11, as an example of resource allocation, the time resource t 6 and frequency resource f″ 1 to f″ 5 Assigned to the corresponding candidate beams from BS recovery beam #1 to BS recovery beam #5. Time resource t 7 and frequency resource f″ 1 to f″ 5 The case of being additionally allocated to the corresponding candidate beams from BS recovery beam #6 to BS recovery beam #10 can correspond to the second case in Table 10.

[0271] The base station 1101 may pre-send information about which candidate beams have been used for CSI-RS transmission to the terminal through a specific message, signal, or signaling. For example, the base station may use DCI, RRC reconfiguration, or newly defined RRC signaling (if newly defined RRC signaling is introduced to apply the present invention) to send information about the beam identifier of the beam used for CSI-RS transmission. In addition, during the process of sending CSI-RS to the terminal, the base station 1101 may send the beam index of its beam recovery candidate beam together with the CSI-RS. The terminal may identify the recovered beam sent by the base station 1101 based on the beam index.

[0272] According to the 5G NR standard, the base station may need to send beams one by one to measure the performance of each candidate beam, thereby performing beam scanning on all candidate beams during the beam recovery process. However, by applying the present invention, beams can be sent simultaneously in different directions based on the beam deflection phenomenon. Therefore, the method according to the present invention can solve the time overhead problem in the beam recovery process of high-frequency band communication systems such as 6G terahertz, which requires a higher level of low-latency communication.

[0273] As described above, when the base station 1101 transmits the recovery beam, the terminal can receive the CSI-RS through the recovery beam. Then, the terminal can receive the CSI-RS transmitted by the base station 1101 and measure the RSRP of the CSI-RS.

[0274] The terminal may report the measured RSRP together with the beam index to the base station. An example of such reported RSRP may be shown in Table 12 below.

[0275] [Table 12]

[0276] Beam recovery candidate beams of the base station (beam index) RSRP Value BS restores beam #1 (000) RSRP_85 BS restores beam #2 (001) RSRP_50 BS restores beam #3 (010) RSRP_61 BS recovery beam #4 (011) RSRP_68 BS recovery beam #5 (100) RSRP_102

[0277] Table 12 provides an example of measuring the RSRP value when the terminal receives five CSI-RS transmissions from the base station 1101, as shown in Table 11. In Table 11, the beam index represents the index of each beam within the candidate beam group configured during the beam recovery process, and the RSRP corresponds to the RSRP measured for each beam index.

[0278] The terminal may report the CSI-RS RSRP of the CSI-RS transmitted by the base station 1101 through the CSI reporting process. The terminal may transmit information about the beam index through the UCI. The reporting process of the RSRP of the CSI-RS transmitted by the recovery candidate beam of the base station may be configured by the base station through the RRC signaling of the UEInformationRequest indicating that the terminal reports the performance of the candidate beam of the base station. The terminal may transmit information about the RSRP of the candidate beam of the base station based on the configuration of the candidate beam performance reporting instruction delivered by the base station through the RRC signaling of the UEInformationRequest.

[0279] As another example, information about the candidate beam performance report instruction from base station 1101 can also be delivered to the terminal via SIB or RRC signaling newly defined according to the present invention. In response to the report instruction, the terminal can use measurement report, UE auxiliary information or RRC signaling newly defined as described above.

[0280] The base station 1101 may then receive information about the performance of the five CSI-RS beams that are candidate beams configured during the beam recovery process. Based on the received performance information and beam index, the base station may identify the best candidate beam. The base station may then reselect the transmit beam based on the best candidate beam reported by the terminal.

[0281] According to Table 12, since the RSRP of the BS-recovered beam #5 corresponding to the beam index 100 is the highest, the base station can determine that the direction in which the BS-recovered beam #5 is the optimal beam direction during the beam recovery process.

[0282] The above process relates to a transmit beam recovery process when a beam failure occurs in a communication link established between the base station 1101 and the terminal. However, the same method can also be extended and applied to a receive beam recovery process.

[0283] Fig.12 is a conceptual diagram showing the overall process of low-latency beam adjustment using beam deflection.

[0284] In step S1200, the base station may send frequency / time resource information for each candidate beam to the terminal. The frequency / time resource information for each candidate beam sent in step S1200 may correspond to the information shown in Tables 2 to 4. In other words, the base station may send information about BS beams, frequency resources, and time resources to the terminal. In this case, the candidate beam may be a frequency-skewed beam as described above. Such a frequency-skewed beam may need to be allocated with equally spaced frequency resource intervals to achieve a uniformly spread pattern from a center frequency, such as Fig.11 In addition, the base station may need to allocate frequency / time resources to ensure full coverage of the angular search space, such as Fig.11 shown.

[0285] In step S1210, the base station may send index mapping information for each candidate beam to the terminal, and send the CSI-RS to the terminal. The process involves assigning a beam index to the corresponding candidate beam of the base station, and sending the CSI-RS together with the beam index, as described in Table 5. As described above, each beam that sends the CSI-RS may be a frequency-skewed beam. In addition, the base station may need to appropriately control the TDN function to ensure that each skewed BS beam is configured to have a predetermined fixed angle. In this case, the base station may simultaneously send the CSI-RS through multiple subcarriers based on the frequency resource allocation information. For example, as shown in Tables 2 to 4, the base station may send the CSI-RS in different directions through 5 subcarriers in a single transmission.

[0286] In step S1220, the terminal may receive CSI-RS through each of the BS beams transmitted by the base station based on the frequency / time resources allocated in step S1200. In this case, as described above, the beam of the terminal may be a fixed beam, and the BS beam is a frequency-skewed beam. The terminal may measure the RSRP of the CSI-RS and report the measured RSRP and its beam index to the base station. The information reported by the terminal to the base station may be in the form of mapping the beam index of the candidate beam of the base station to the RSRP, as described in Table 6.

[0287] The above steps S1210 and S1220 may be repeatedly performed. For example, if the time resource is configured for more than two scans, steps S1210 and S1220 may be repeated. In other words, Fig.11 As shown, if the system is configured for three scans, the base station can 1 Send candidate beams, as described in step S1210. Accordingly, as described in step S1220, the terminal can 1 The corresponding reporting time reports the RSRP of the CSI-RS for the candidate beam. Then, the base station can2 Send candidate beams, as described in step S1210. Similarly, as described in step S1220, the terminal may 2 The corresponding reporting time reports the RSRP of the CSI-RS for the candidate beam. Finally, the base station can 3 Send candidate beams, as described in step S1210. Accordingly, as described in step S1220, the terminal can 3 The corresponding reporting time reports the RSRP of the CSI-RS for the candidate beam.

[0288] As described above, CSI-RS transmission and CSI-RSRSRP reporting between the base station and the terminal may be performed according to the number of scanning times.

[0289] In step S1230, the base station may select the best transmit beam based on the CSI-RS RSRP reported by the terminal. For example, if the information mapping the beam index of the candidate beam to the RSRP reported by the terminal corresponds to Table 6, the base station may select BS beam #7 with the highest RSRP as the best transmit beam. In this case, as described above, when the number of scans between the base station and the terminal has been determined, the best transmit beam may be selected after all reports for the determined number of scans are received from the terminal.

[0290] Through the process described in the above steps S1200 to S1230, the process for adjusting the transmission beam of the base station can be performed. Hereinafter, the process for adjusting the reception beam will be described.

[0291] In step S1240, the terminal may configure its candidate beam group and report (or deliver) the number of candidate beams to the base station. In this case, the candidate beam may be a narrower beam that subdivides the fixed beam in step S1220. The candidate beam group may include information such as that described in Table 7.

[0292] In step S1250, the base station may allocate frequency / time resources for CSI-RS transmission based on the information about the number of candidate beams for receiving beam adjustment provided by the terminal. Using the allocated resources, the base station may transmit CSI-RS to the terminal. In this case, the base station may fix its beam to the best transmission beam configured in step S1230.

[0293] In step S1260, the terminal may form a receive beam to receive the CSI-RS transmitted by the base station, and receive the CSI-RS through the frequency / time resources allocated in step S1250. Then, the terminal may measure the RSRP of the CSI-RS transmitted by the base station. If the base station determines that the number of scans is 2 or more, steps S1250 and S1260 may be repeated.

[0294] In step S1270, the terminal may select the best beam based on the RSRP of the CSI-RS transmitted by the base station. In this case, as described above, if the number of scans is set to 2 or more, the terminal may receive beams for the number of scans and determine the best beam based on the RSRP of the measured CSI-RS.

[0295] Fig.13 is a sequence diagram illustrating a method of low-latency beam adjustment using beam deflection.

[0296] exist Fig.13 In FIG. 1 , a base station 1301 and a terminal 1302 are shown. The base station 1301 and the terminal 1302 may each include Figure 2 All or part of the components of the communication node described in.

[0297] like Fig.13 As shown, in step S1310, base station 1301 may allocate frequency / time resources to corresponding candidate beams. Allocating such candidate resources may involve information as described in Tables 2 to 4. In this case, the candidate beam may be a frequency-skewed beam as described above. The frequency-skewed beam may need to be allocated with uniformly spaced frequency resources to achieve a uniform spreading pattern from a center frequency, such as Fig.11 In addition, the base station may need to allocate frequency / time resources to ensure full coverage of the angular search space, such as Fig.11 described.

[0298] In step S1315, the base station 1301 may send resource allocation information of the frequency / time resources for the candidate beam to the terminal 1302. The resource allocation information of the frequency / time resources for the candidate beam may be sent using DCI, MAC-CE, RRC reconfiguration message, or RRC signaling newly defined according to the present invention. Therefore, in step S1315, the terminal 1302 may receive resource allocation information for the candidate beam from the base station 1301.

[0299] In step S1320, the base station 1301 may map the beam index to each of the candidate beams. As described in Table 5, the number of bits required to allocate the beam index may be determined based on the number of candidate beams, and the beam index may be determined based on the calculated number of bits. In addition, when mapping the beam index to the corresponding candidate beams, the base station 1301 may map them sequentially within the angle search space.

[0300] In step S1325, the base station 1301 may send a beam index and a CSI-RS through the corresponding candidate beam. In this case, the candidate beam may be a beam based on the deflection of the subcarrier frequency, as described above. In addition, the degree of deflection for each subcarrier may be appropriately adjusted using the TDN function, as described above. Therefore, Fig.11 As shown, the beam may be deflected and transmitted in a single transmission to cover a specific range. In step S1325, the base station 1302 may receive a beam index and a CSI-RS transmitted by the base station through the candidate beam.

[0301] In step S1330, the terminal 1302 may measure the RSRP of the CSI-RS included in the received beam. The RSRP measured for the corresponding candidate beam may be exemplified as shown in Table 6. In this case, the terminal 1302 may use a single fixed reception beam.

[0302] In addition, as described above, if the candidate beams of the base station 1301 cannot be transmitted at once, in other words, if they need to be transmitted by beam scanning, steps S1325 and S1330 may be repeated the number of times of scanning.

[0303] In step S1335, the terminal 1302 may report the measured RSRP for the corresponding candidate beam to the base station 1301. If the terminal 1302 is preconfigured to report only a preconfigured number of RSRPs, the terminal may sort the RSRPs in descending order and send only the preconfigured number of top RSRPs and their mapped beam indexes. For ease of description, the present invention assumes a case where all RSRPs for all candidate beams are reported, as illustrated in Table 6.

[0304] In step S1340, the base station 1301 may select the best transmission beam based on all RSRPs of all candidate beams reported from the terminal 1302. In this case, the best transmission beam may be the beam with the highest RSRP. If the beam overlaps with a specific other terminal, the base station may select the beam with the second highest RSRP, or select the beam with the highest RSRP in another direction among the beams that do not cause interference.

[0305] Based on the above operation, it is possible to determine the transmission beam of the base station 1301. Hereinafter, an operation for determining the reception beam of the terminal will be described.

[0306] In step S1350, the terminal 1302 may determine its candidate beam group. In this case, the candidate beam group may include a finer receiving beam into which the fixed receiving beam used in step S1330 is subdivided. In other words, the fixed receiving beam used in step S1330 may be subdivided into narrower beams. The candidate beam group may be configured as described with reference to Table 7. In addition, Table 7 is only an example, and the number of candidate beams included in the beam candidate group may vary. For example, the candidate beam group may be configured with 5 or fewer beams. Alternatively, the candidate beam group may be configured with 7 or more beams.

[0307] In step S1355, the terminal 1302 may transmit information about the number of its candidate beams to the base station 1301. Accordingly, in step S1355, the base station 1301 may obtain information about the number of candidate beams transmitted by the terminal 1302.

[0308] In step S1360, the base station 1301 may allocate frequency / time resources for CSI-RS transmission based on the number of candidate beams of the terminal. In this case, the beam used for CSI-RS transmission may be the best transmission beam determined in step S1340.

[0309] In step S1365, the base station 1301 may transmit the CSI-RS through the optimal transmission beam. Accordingly, in step S1365, the terminal 1302 may receive the CSI-RS transmitted by the base station 1301.

[0310] In step S1370, the terminal 1302 may measure the CSI-RS transmitted by the base station 1301 using the reception beam belonging to its candidate beam group. In this case, the terminal 1302 may use beam deflection to simultaneously receive multiple beams. The terminal 1302 may measure the RSRP of the received CSI-RS and select the best reception beam based on the measured RSRP.

[0311] Fig.14 is a conceptual diagram showing the overall process of low-latency beam recovery using beam deflection.

[0312] In step S1410, the base station may determine a candidate beam group to be measured based on the delay requirement of the terminal. In other words, the base station may determine a beam direction within the angle search space based on the delay requirement of the terminal and the time required for beam scanning, as described in Table 10, and then determine a candidate beam group to be transmitted based on the determined beam direction.

[0313] In step S1420, the base station may map the beam index based on the beam direction in the angular search space. The beam index mapping may represent the relationship between the beam recovery candidate beams of the base station and their beam indexes, as described in Table 11. Therefore, the method described in Equation 3 may be used to determine the number of binary bits required to identify the beam index.

[0314] On the other hand, despite Fig.14 Not shown in the figure, before executing step S1430, the base station may send information instructing the terminal to report the performance of the restored candidate beam. Since the reporting instruction information has been described above, redundant description is omitted.

[0315] In step S1430, the base station may allocate frequency / time resources for CSI-RS transmission, and transmit the CSI-RS to the terminal using the allocated frequency / time resources.

[0316] In step S1440, the terminal may receive the CSI-RS transmitted by the base station. In other words, the terminal may measure the RSRP of the CSI-RS transmitted by the base station and report the measured RSRP and beam index to the base station. The report may be performed as described with reference to Table 11. Alternatively, if the number of RSRPs to be reported is preconfigured, the terminal may sort the RSRPs in descending order and report only the preconfigured number of RSRPs starting from the highest RSRP.

[0317] In step S1450, the base station may reselect an optimal transmission beam based on the RSRP of the CSI-RS reported from the terminal.

[0318] Fig.15 is a sequence diagram illustrating a low-latency beam adjustment method using beam deflection.

[0319] exist Fig.15 In FIG. 1 , a base station 1501 and a terminal 1502 are shown. The base station 1501 and the terminal 1502 may each include Figure 2 In addition, when a beam failure occurs in the communication link between the base station and the terminal, the following may be performed: Fig.15 Therefore, Fig.15 The sequence diagram assumes a scenario in which the terminal 1502 has sent a beam failure recovery request message to the base station 1501.

[0320] like Fig.15 As shown in , in step S1510, the base station 1501 can determine the candidate beam group to be measured based on the delay requirement of the terminal. In this case, the candidate beam group can be determined based on the delay requirement, the number of beam scans and the angle search space.

[0321] In step S1520, the base station 1501 may map the beam index based on the beam direction in the angle search space. The beam index mapping may correspond to the relationship between the beam recovery candidate beams of the base station and the beam index, as described in Table 11. Accordingly, the method described in Equation 3 may be used to determine the number of binary bits required to identify the beam index.

[0322] In step S1530, the base station 1501 may allocate frequency / time resources to the corresponding candidate beams. The frequency / time resources may be allocated using the same or similar methods as those described with reference to Tables 2 to 4. In addition, as described in the beam adjustment process, frequency resources may be selected and allocated to ensure that the beams are evenly distributed.

[0323] Despite Fig.15 Not shown in the figure, before executing step S1540, the base station may send information instructing the terminal to report the performance of the restored candidate beam. Since the reporting instruction information has been described above, redundant description is omitted.

[0324] In step S1540, the base station 1501 can use the allocated resources to send the beam index and CSI-RS through the beam. In this case, as described above, the beam using the allocated resources can be a deflected beam, and can be a beam adjusted to have an appropriate angle using the TDN function. Accordingly, the terminal 1502 can receive the deflected beam using the allocated resources. In other words, the terminal 1502 can receive the beam index and CSI-RS through the candidate beam.

[0325] In step S1550, the terminal 1502 may measure the RSRP of the received CSI-RS. The measured RSRP of the CSI-RS may be stored in the terminal 1502 as described in Table 12. If necessary, the terminal 1502 may sort the RSRP in descending or ascending order.

[0326] In step S1560, the terminal 1502 may report the beam index and RSRP of the CSI-RS to the base station 1501. If only a predetermined number of RSRPs are configured for reporting, the terminal 1502 may only report the predetermined number of RSRPs starting from the highest RSRP and their corresponding beam indexes.

[0327] In step S1570, the base station 1501 may select the best transmission beam based on the RSRP of the received CSI-RS. The best transmission beam may be the beam with the highest RSRP.

[0328] Although Fig.15 Only the method for recovering the transmit beam is shown, and the method for recovering the receive beam may also be performed in the same or similar manner based on the above-mentioned beam adjustment method.

[0329] The operation of the method according to the exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include a recording device of all types having data that can be read by a computer system. In addition, the computer-readable recording medium can store and execute programs or codes, which can be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0330] Computer readable recording media may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM or flash memory. Program instructions may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0331] Although some aspects of the present invention have been described in the context of a device, these aspects may indicate the corresponding description according to the method, and a block or device may correspond to the step of the method or the feature of the step. Similarly, the aspects described in the context of the method may be represented as the feature of a corresponding block or project or a corresponding device. Some or all steps of the method may be performed by (or using) a hardware device such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important steps of the method may be performed by such a device.

[0332] In some exemplary embodiments, a programmable logic device such as a field programmable gate array can be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the field programmable gate array can be operated with a microprocessor to perform one of the methods described herein. Typically, the method is preferably performed by a specific hardware device.

[0333] The description of the present invention is merely exemplary in nature, and therefore variant forms that do not deviate from the essence of the present invention are intended to be within the scope of the present invention. Such variant forms should not be considered as departing from the spirit and scope of the present invention. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of a base station, comprising: allocating a first resource for transmitting a candidate beam, the candidate beam being determined based on a number of subcarriers to be deflected by the beam within an angle search space and a number of scans of a beam formed using the subcarriers to be deflected by the beam; sending first resource information indicating an allocated first resource to a user equipment (UE); Mapping a beam index to each of the candidate beams; sending information about a beam index mapped to each of the candidate beams to the UE; Sending a first reference signal using a first resource through a candidate beam; receiving reception quality information for a first reference signal from the UE; as well as A transmission beam is determined based on the reception quality information.

2. The method according to claim 1, wherein: The first resource information indicates frequency resources and time resources, each of the frequency resources corresponds to a frequency of each of subcarriers used to form a candidate beam, and each of the time resources corresponds to a transmission time of each of the candidate beams based on a number of scans.

3. The method according to claim 1, wherein: The frequencies of the subcarriers are arranged such that differences between frequencies of adjacent subcarriers have the same value.

4. The method according to claim 1, wherein: When the first reference signal is transmitted through the candidate beams, a time delay network (TDN) function is controlled so that main lobes of the candidate beams do not overlap with each other and angles between the candidate beams have a uniform angle difference.

5. The method according to claim 1, wherein: First resource information allocated to candidate beams and information about beam indexes mapped to each of the candidate beams are sent to the UE using at least one of downlink control information (DCI), medium access control-control element (MAC-CE), or radio resource control (RRC) reconfiguration information.

6. The method according to claim 1, further comprising: receiving, from the UE, information about a number of candidate beams for the UE; determining a second resource for sending a second reference signal based on the number of candidate beams of the UE; as well as The second reference signal is sent to the UE using the determined second resource.

7. The method according to claim 6, further comprising: When the second reference signal is transmitted through the transmit beam, before the second reference signal is transmitted to the UE, it is indicated that the transmit beam is fixed by using a repetition parameter in an information element of a reference signal resource set of RRC reconfiguration information.

8. The method according to claim 6, wherein: The information about the number of candidate beams of the UE is received using at least one of uplink control information (UCI), UE assistance information, or UE performance information.

9. A method of a user equipment (UE), comprising: receiving first resource information from a base station, the first resource information indicating a first resource allocated to a candidate beam sent by the base station; receiving, from a base station, information about a beam index mapped to each of the candidate beams; receiving a first signal from a base station through a candidate beam using a preconfigured reception beam, the first signal including a first reference signal and information about a beam index corresponding to each of the candidate beams; measuring a reception quality of each received first reference signal through the candidate beams; as well as transmitting information about the measured reception quality and information about an index of each of the candidate beams corresponding to the measured reception quality to the base station, The candidate beams are determined based on the number of subcarriers to be deflected by the beam in the angle search space and the number of beam scans formed using the subcarriers to be deflected by the beam.

10. The method according to claim 9, wherein: The first resource information indicates frequency resources and time resources, each of the frequency resources corresponds to a frequency of each of subcarriers used to form a candidate beam, and each of the time resources corresponds to a transmission time of each of the candidate beams based on a number of scans.

11. The method according to claim 9, wherein: The frequencies of the subcarriers are arranged such that differences between frequencies of adjacent subcarriers have the same value.

12. The method according to claim 9, wherein: Using at least one of downlink control information (DCI), medium access control-control element (MAC-CE), or radio resource control (RRC) reconfiguration information, each of first resource information allocated to candidate beams and information of a beam index indicated by a first signal received through each of the candidate beams is received.

13. The method according to claim 9, further comprising: Determine a UE candidate beam group by dividing a pre-configured receive beam into a plurality of subdivided beams; Sending information about the number of beams of the UE candidate beam group to the base station; receiving a second reference signal using a beam belonging to a UE candidate beam group; measuring a signal quality of a second reference signal; as well as A receive beam is determined based on the measured signal quality of the second reference signal.

14. The method according to claim 13, further comprising: Second information is received before receiving the second reference signal, the second information indicating that the transmit beam is fixed.

15. The method according to claim 14, wherein: The second information is indicated by using a repetition parameter in an information element of a reference signal resource set of the RRC reconfiguration information.

16. The method according to claim 13, wherein: The information about the number of candidate beams of the UE is transmitted using at least one of uplink control information (UCI), UE assistance information, or UE performance information.

17. A user equipment (UE) comprising at least one processor, wherein the at least one processor causes the UE to perform: receiving first resource information from a base station, the first resource information indicating a first resource allocated to a candidate beam sent by the base station; receiving, from a base station, information about a beam index mapped to each of the candidate beams; receiving a first signal from a base station through a candidate beam using a preconfigured reception beam, the first signal including a first reference signal and information about a beam index corresponding to each of the candidate beams; measuring a reception quality of each received first reference signal through the candidate beams; as well as transmitting information about the measured reception quality and information about an index of each of the candidate beams corresponding to the measured reception quality to the base station, The candidate beams are determined based on the number of subcarriers to be deflected by the beam in the angle search space and the number of beam scans formed using the subcarriers to be deflected by the beam.

18. The UE according to claim 17, wherein: The first resource information indicates frequency resources and time resources, each of the frequency resources corresponds to a frequency of each of subcarriers used to form a candidate beam, and each of the time resources corresponds to a transmission time of each of the candidate beams based on a number of scans.

19. The UE according to claim 17, wherein: The at least one processor further causes the UE to execute: Determine a UE candidate beam group by dividing a pre-configured receive beam into a plurality of subdivided beams; Sending information about the number of beams of the UE candidate beam group to the base station; receiving a second reference signal using a beam belonging to a UE candidate beam group; measuring a signal quality of a second reference signal; as well as A receive beam is determined based on the measured signal quality of the second reference signal.

20. The UE according to claim 19, wherein: The at least one processor further causes the UE to perform: receiving second information before receiving the second reference signal, the second information indicating that the transmit beam is fixed, The second information is indicated by using a repetition parameter in an information element of a reference signal resource set of the RRC reconfiguration information.

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