Method and apparatus for beam management in communication system having extra-large scale multiple input and multiple output

Abstract

A method of a terminal according to the present disclosure comprises the steps of: transmitting a first signal including a terminal beam index and a first RS for each beam to a base station by beam sweeping terminal beams; receiving scatterer information existing on a communication path between the terminal and the base station from the base station; receiving information on the number of estimation steps for antenna estimation from the base station; performing a first procedure of hierarchically estimating, for each scatterer included in the scatterer information and the base station, VRs among antennas of the base station as many as the information on the number of estimation steps; and performing a second procedure for determining a base station beam to be used by the base station and each VR.

Description

Method and device for beam management in a communication system having ultra-large-scale multiple input multiple output

[0001] The present disclosure relates to improved communication technologies, and more particularly to technologies for beam management in communication systems having extra-large scale multiple input multiple output (XL-MIMO).

[0002] Communication networks (e.g., 5G communication networks, 6G communication networks, etc.) are being developed to provide improved communication services compared to existing communication networks (e.g., long term evolution (LTE), advanced LTE-A (LTE-A), etc.). 5G communication networks (e.g., new radio (NR) communication networks) can support frequency bands above 6 GHz as well as frequency bands below 6 GHz. That is, 5G communication networks can support FR1 bands and / or FR2 bands. 5G communication networks can support various communication services and scenarios compared to LTE communication networks. For example, usage scenarios of 5G communication networks can include enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), etc.

[0003] Compared to 5G, 6G communication networks can support a wider range of communication services and scenarios. 6G communication networks can meet requirements for ultra-high performance, ultra-high bandwidth, ultra-high space, ultra-high precision, ultra-intelligence, and / or ultra-reliability. 6G communication networks can support diverse and wide frequency bands and be applied to various usage scenarios (e.g., terrestrial communications, non-terrestrial communications, sidelink communications, etc.).

[0004] Meanwhile, 5G communication systems utilize a massive multiple input multiple output (MIMO) system to simultaneously service multiple devices and achieve higher data transmission rates. When a base station utilizes a massive MIMO system, it focuses its beams on specific locations when transmitting information to a device. This not only enables higher data transmission rates but also lower inter-user interference and higher energy efficiency.

[0005] When using Frequency Range 2 (FR2) in 5G systems and / or the higher frequency bands expected for 6G systems, transmitted signals experience high path attenuation, resulting in reduced communication range. One way to compensate for this reduced communication range is through the use of a massive MIMO system.

[0006] Despite the advantages described above, current massive MIMO systems have the limitation of having difficulty achieving sufficient spatial dimensionality because they utilize a very large number of antennas placed in a narrow space. Future 6G communication systems are considering deploying multiple antennas on the walls of large buildings, such as airports, shopping malls, and stadiums, to achieve additional spatial dimensionality beyond massive MIMO systems. Systems that deploy even more antennas over a wide area to achieve additional spatial dimensionality than massive MIMO systems are defined as extra-large scale massive MIMO (XL-MIMO) systems.

[0007] Therefore, a method and device for managing beams in an XL-MIMO system are required.

[0008] The purpose of the present disclosure to solve the above problems is to provide a method and device for beam management in a communication system having XL-MIMO.

[0009] In order to achieve the above object, a method of a terminal according to a first embodiment of the present disclosure comprises the steps of beam-sweeping terminal beams and transmitting a first signal including a terminal beam index and a first reference signal (RS) for each beam to a base station; receiving, from the base station, information on scatterers existing on a communication path between the terminal and the base station; receiving, from the base station, information on the number of estimation steps for antenna estimation; performing a first procedure for hierarchically estimating visibility regions (VRs) among antennas of the base station for each scatterer included in the base station and the scatterer information as much as the number of estimation steps information; and performing a second procedure for determining a base station beam to be used in the base station and each VR.

[0010] The above scatterer information may include a scatterer identifier and a terminal beam index corresponding to the scatterer.

[0011] After receiving the above scattering information, the method may further include a step of transmitting service information and VR-related information to be provided from the terminal to the base station.

[0012] The above VR-related information may include at least one of information on whether the VR supports hierarchical estimation or information on the number of beams that the terminal can form simultaneously.

[0013] The above first procedure is,

[0014] The method may further include receiving an RS transmission instruction from the base station through a terminal beam corresponding to at least one scatterer among the scatterers included in the scatterer information; and transmitting an RS based on the RS transmission instruction.

[0015] The above RS transmission instructions are:

[0016] It may include at least one of a period for transmitting the RS, a time point for transmitting the RS, or a number of times for transmitting the RS.

[0017] The second procedure above is:

[0018] The method may further include: receiving an RS transmission instruction from the base station through a terminal beam corresponding to at least one scatterer among the scatterer information included in the scatterer information; transmitting a second signal including a second RS based on the RS transmission instruction; receiving a reference signals received power (RSRP) measurement report instruction message including terminal beam information from the base station; measuring an RSRP of an RS received from the base station through the terminal beam indicated in the terminal beam information; and reporting the measured RSRP to the base station.

[0019] The base station has an extra-large scale multiple input multiple output (XL-MIMO) antenna, and the scattering objects may include at least one of a building, a vehicle, a person, a sculpture, an intelligent reflecting surface (IRS), a reconfigurable intelligent surface (RIS), or airborne particles.

[0020] A method of a base station according to an embodiment of the present disclosure may include: receiving a first signal including a reference signal from a terminal by beam-sweeping the first signal through an entire antenna array of an extra-large scale multiple input multiple output (XL-MIMO) antenna; obtaining scatterer information by measuring a first reference signal received power (RSRP) of the first signal; transmitting the obtained scatterer information to the terminal; determining a number of steps for estimating the XL-MIMO antenna; transmitting the determined number of steps information to the terminal; performing a first procedure for hierarchically estimating visibility regions (VRs) among the XL-MIMO antennas for each scatterer included in the scatterer information by the number of estimation steps information; and performing a second procedure for determining a base station beam to be used in one or more VR regions with the terminal.

[0021] The above scatterer information may include a scatterer identifier and a terminal beam index corresponding to the scatterer.

[0022] After transmitting the scattering information, a step of receiving service information and VR-related information of the terminal from the terminal may be further included.

[0023] The above VR-related information may include at least one of information on whether the VR supports step-by-step estimation or information on the number of beams that the terminal can form simultaneously.

[0024] The above first procedure is,

[0025] A step of determining the number of estimation steps of the VRs; and a step of performing a third procedure for determining VRs in the entire array of XL-MIMO antennas as many times as the number of estimation steps may be further included.

[0026] The estimated number of steps of the above VRs can be determined based on at least one of the delay requirement received from the terminal or the number of antenna ports that the base station can simultaneously transmit and receive.

[0027] The above third procedure is for each of the above scatterers:

[0028] The method may further include: dividing the entire XL-MIMO antenna array into a predetermined number of first antenna regions; selecting first representative antennas for each of the divided first antenna regions; measuring a second RSRP of an RS received from the terminal through the first representative antennas; determining the first antenna region(s) including the first representative antennas having the second RSRP exceeding a preset first threshold as a VR candidate region; dividing each of the VR candidate regions into a predetermined number of second antenna regions; selecting second representative antennas for each of the divided second antenna regions; measuring a third RSRP of an RS received from the terminal through the second representative antennas; and determining the second antenna region(s) including the second representative antennas having the third RSRP exceeding a preset second threshold as a VR region.

[0029] The second procedure above, for each scatterer:

[0030] The method may further include: transmitting an RS transmission instruction message through a terminal beam corresponding to the scatterer; measuring a fourth RSRP of an RS received from the terminal through antennas in the VR region; determining a combination between the measured scatterer and the VR region based on the measured fourth RSRP; and performing a fourth procedure of determining a segmented beam to communicate with the terminal based on the combination between the scatterer and the VR region.

[0031] The above fourth procedure is:

[0032] The method may further include: transmitting combination information between the determined scatterer and VR region to the terminal; subdividing each of the base station beams to be transmitted through the VR regions into a predetermined number; transmitting an RSRP measurement report instruction message including the terminal beam information to the terminal; determining combinations composed of pairs of subdivided beams of the different VR regions; transmitting RS to the terminal through beams based on the combinations of pairs of the subdivided beams; receiving an RSRP report message corresponding to beams based on the combinations of the subdivided beams from the terminal; and determining a base station beam from among the subdivided beams based on the received RSRP report message.

[0033] A terminal according to an embodiment of the present disclosure comprises at least one processor, wherein the at least one processor:

[0034] A method of transmitting a first signal including a terminal beam index and a first reference signal (RS) for each beam to a base station by beam-sweeping terminal beams; receiving, from the base station, information on scatterers existing on a communication path between the terminal and the base station; receiving, from the base station, information on the number of estimation steps for antenna estimation; performing a first procedure for hierarchically estimating visibility regions (VRs) among antennas of the base station for each scatterer included in the base station and the scatterer information as much as the number of estimation steps information; and performing a second procedure for determining a base station beam to be used in the base station and each VR.

[0035] The above scatterer information may include a scatterer identifier and a terminal beam index corresponding to the scatterer.

[0036] At least one processor of the above:

[0037] After receiving the above scattering information, the service information and VR-related information to be provided from the terminal may be further transmitted to the base station.

[0038] The above VR-related information may include at least one of information on whether the VR supports step-by-step estimation or information on the number of beams that the terminal can form simultaneously.

[0039] At least one processor, in the first procedure:

[0040] Receive an RS transmission instruction from the base station through a terminal beam corresponding to at least one scatterer among the scatterers included in the scatterer information; and further cause an RS to be transmitted based on the RS transmission instruction.

[0041] The above RS transmission instructions are:

[0042] It may include at least one of a period for transmitting the RS, a time point for transmitting the RS, or a number of times for transmitting the RS.

[0043] At least one processor in the second procedure,

[0044] The method may further cause the base station to receive an RS transmission instruction through a terminal beam corresponding to at least one scatterer among the scatterer information included in the scatterer information; and transmit a second signal including a second RS based on the RS transmission instruction; receive a reference signals received power (RSRP) measurement report instruction message including terminal beam information from the base station; measure an RSRP of an RS received from the base station through the terminal beam indicated in the terminal beam information; and report the measured RSRP to the base station.

[0045] According to the present disclosure, a communication path through scatterers can be established in a base station and a terminal having XL-MIMO antennas. Furthermore, when there are two or more scatterers, a communication path through an optimal scatterer can be established. A terminal beam corresponding to the optimal scatterer can be selected. Furthermore, by gradually finding a VR area in an XL-MIMO antenna array, there is an advantage in that the area of ​​antenna arrays capable of communicating with a terminal can be reduced. Furthermore, by further segmenting the beams in the selected antenna array, there is an advantage in that interference with other terminals can be reduced.

[0046] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0047] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0048] Figure 3 is a block diagram illustrating a first embodiment of communication nodes performing communication.

[0049] Figure 4a is a block diagram illustrating a first embodiment of a transmission path.

[0050] Figure 4b is a block diagram illustrating a first embodiment of a receiving path.

[0051] Figure 5 is a conceptual diagram illustrating a first embodiment of a system frame in a communication system.

[0052] Figure 6 is a conceptual diagram illustrating a first embodiment of a subframe in a communication system.

[0053] Figure 7 is a conceptual diagram illustrating a first embodiment of a slot in a communication system.

[0054] Figure 8 is a conceptual diagram illustrating a first embodiment of time-frequency resources in a communication system.

[0055] Figure 9 is a conceptual diagram illustrating a case where a base station having XL-MIMO communicates with a terminal.

[0056] Figure 10 is a conceptual diagram illustrating a method for finding scatterers existing in a communication link between a base station and a terminal.

[0057] FIG. 11a is a flowchart according to a first embodiment for detecting scatterers present on a communication path between a base station and a terminal.

[0058] Figure 11b is a flowchart according to a second embodiment for detecting scatterers present on a communication path between a base station and a terminal.

[0059] Figure 12a is a flowchart of part of the operation for hierarchical VR estimation at a base station.

[0060] Figure 12b is a flowchart of the remaining hierarchical VR estimation operation at the base station.

[0061] Figure 13a is a conceptual diagram for explaining the division of antenna areas in the entire antenna array of an XL-MIMO antenna panel and the representative antenna settings for each area.

[0062] Figure 13b is a conceptual diagram illustrating the procedure for dividing the antenna array and selecting a representative antenna in the second stage of VR estimation.

[0063] FIG. 14a is a flowchart of part of an operation for selecting a base station beam and a terminal beam in a communication system using an XL-MIMO antenna.

[0064] Figure 14b is a remaining flowchart of operations for selecting a base station beam and a terminal beam in a communication system using an XL-MIMO antenna.

[0065] Figure 15 is a conceptual diagram for explaining a beam management method considering VR in a communication system using an XL-MIMO antenna.

[0066] This disclosure may be subject to various modifications and various embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the disclosure.

[0067] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" may refer to a combination of multiple related items described herein or to any of multiple related items described herein.

[0068] In the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Additionally, in the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.”

[0069] In the present disclosure, (re)transmission may mean “transmission,” “retransmission,” or “transmission and retransmission,” (re)setting may mean “setting,” “resetting,” or “setting and resetting,” (re)connection may mean “connection,” “reconnection,” or “connection and reconnection,” and (re)connection may mean “connection,” “reconnection,” or “connection and reconnection.”

[0070] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0071] The terminology used in this disclosure is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0072] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0073] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding in describing the present disclosure, the same reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted. In addition to the embodiments explicitly described in the present disclosure, operations may be performed according to combinations of embodiments, extensions of embodiments, and / or modifications of embodiments. The performance of some operations may be omitted, and the order of operation may be changed.

[0074] In an embodiment, even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, if an operation of a UE (user equipment) is described, a corresponding base station can perform an operation corresponding to the operation of the UE. Conversely, if an operation of a base station is described, a corresponding UE can perform an operation corresponding to the operation of the base station.

[0075] A base station may be referred to as a NodeB, an evolved NodeB, a gNodeB (next generation node B), a gNB, a device, an apparatus, a node, a communication node, a BTS (base transceiver station), a RRH (radio remote head), a TRP (transmission reception point), a RU (radio unit), an RSU (road side unit), a radio transceiver, an access point, an access node, etc. A UE may be referred to as a terminal, a device, an apparatus, a node, a communication node, an end node, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, an OBU (on-broad unit), etc.

[0076] In the present disclosure, signaling may be at least one of upper layer signaling, MAC signaling, or PHY (physical) signaling. A message used for upper layer signaling may be referred to as an "upper layer message" or an "upper layer signaling message." A message used for MAC signaling may be referred to as a "MAC message" or a "MAC signaling message." A message used for PHY signaling may be referred to as a "PHY message" or a "PHY signaling message." Upper layer signaling may refer to a transmission and reception operation of system information (e.g., a master information block (MIB), a system information block (SIB)) and / or an RRC message. MAC signaling may refer to a transmission and reception operation of a MAC control element (CE). PHY signaling may refer to a transmission and reception operation of control information (e.g., downlink control information (DCI), uplink control information (UCI), sidelink control information (SCI)).

[0077] In the present disclosure, “an operation (e.g., a transmission operation) is set” may mean that “setting information for the operation (e.g., an information element, a parameter)” and / or “information instructing the performance of the operation” is signaled. “An information element (e.g., a parameter) is set” may mean that the information element is signaled. In the present disclosure, “a signal and / or a channel” may mean a signal, a channel, or “a signal and a channel,” and a signal may be used to mean “a signal and / or a channel.”

[0078] The communication network to which the embodiment is applied is not limited to what is described below, and the embodiment may be applied to various communication networks (e.g., 4G communication networks, 5G communication networks, and / or 6G communication networks). Here, the communication network may be used in the same sense as the communication system.

[0079] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0080] Referring to FIG. 1, 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, 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 (P-GW), a mobility management entity (MME)). If the communication system (100) is a 5G communication system (e.g., a new radio (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.

[0081] A plurality of communication nodes (110 to 130) can support a communication protocol (e.g., LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.) specified in the 3GPP (3rd generation partnership project) standard. The plurality of communication nodes (110 to 130) may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (non-orthogonal multiple access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (space division multiple access) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0082] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0083] Referring to FIG. 2, a communication node (200) may include at least one processor (210), a memory (220), and a transmission / reception device (230) that is connected to a network and performs 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) may be connected by a bus (270) and communicate with each other.

[0084] The processor (210) can execute program commands 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 in which the methods according to embodiments of the present disclosure are performed. Each of the memory (220) and the storage device (260) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0085] Referring again to FIG. 1, the communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). 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. 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 be within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be within the cell coverage of the third base station (110-3). The first terminal (130-1) may be within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be within the cell coverage of the fifth base station (120-2).

[0086] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as a NodeB (NB), an evolved NodeB (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 (TP), a transmission and reception point (TRP), etc.

[0087] Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a 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.

[0088] Meanwhile, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to the core network via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0089] Additionally, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may support MIMO transmission (e.g., single user (SU)-MIMO, multi user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, sidelink communication (e.g., device to device communication (D2D), proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO scheme, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) by the SU-MIMO scheme. Alternatively, the second base station (110-2) can transmit signals to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive signals from the second base station (110-2) based on the MU-MIMO method.

[0090] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP scheme, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) based on the CoMP scheme. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive a signal with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage based on the CA scheme. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control sidelink communication between the fourth terminal (130-4) and the fifth terminal (130-5), and each of 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.

[0091] Meanwhile, communication nodes performing communication in a communication network may be configured as follows. The communication node illustrated in Fig. 3 may be a specific embodiment of the communication node illustrated in Fig. 2.

[0092] Figure 3 is a block diagram illustrating a first embodiment of communication nodes performing communication.

[0093] Referring to FIG. 3, each of the first communication node (300a) and the second communication node (300b) may be a base station or a UE. The first communication node (300a) may transmit a signal to the second communication node (300b). The transmission processor (311) included in the first communication node (300a) may receive data (e.g., a data unit) from a data source (310). The transmission processor (311) may 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).

[0094] The transmitting processor (311) may perform a processing operation on data (e.g., an encoding operation, a symbol mapping operation, etc.) to generate data symbol(s). The transmitting processor (311) may perform a processing operation on control information (e.g., an encoding operation, a symbol mapping operation, etc.) to generate control symbol(s). In addition, the transmitting processor (311) may generate synchronization / reference symbol(s) for a synchronization signal and / or a reference signal.

[0095] The Tx MIMO processor (312) may perform a spatial processing operation (e.g., a precoding operation) on data symbol(s), control symbol(s), and / or synchronization / reference symbol(s). The output (e.g., a symbol stream) of the Tx MIMO processor (312) may be provided to modulators (MODs) included in the transceivers (313a to 313t). The modulators (MODs) may perform a processing operation on the symbol stream to generate modulation symbols, and may perform an additional processing operation (e.g., an analog conversion operation, an amplification operation, a filtering operation, an upconversion operation) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (313a to 313t) may be transmitted via the antennas (314a to 314t).

[0096] Signals transmitted by the first communication node (300a) may be received by antennas (364a to 364r) of the second communication node (300b). Signals received by the antennas (364a to 364r) may be provided to demodulators (DEMODs) included in transceivers (363a to 363r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (362) may perform a MIMO detection operation on the symbols. The receiving processor (361) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (361) may be provided to a data sink (360) and a controller (366). For example, data may be provided to the data sink (360), and control information may be provided to the controller (366).

[0097] Meanwhile, the second communication node (300b) can transmit a signal to the first communication node (300a). The transmitting processor (368) included in the second communication node (300b) can receive data (e.g., data units) from a data source (367) and perform a processing operation on the data to generate data symbol(s). The transmitting processor (368) can receive control information from the controller (366) and perform a processing operation on the control information to generate control symbol(s). In addition, the transmitting processor (368) can perform a processing operation on a reference signal to generate reference symbol(s).

[0098] The Tx MIMO processor (369) may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and / or reference symbol(s). The output (e.g., symbol stream) of the Tx MIMO processor (369) may be provided to modulators (MODs) included in the transceivers (363a to 363t). The modulators (MODs) may perform processing operations on the symbol streams to generate modulation symbols, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (363a to 363t) may be transmitted via the antennas (364a to 364t).

[0099] Signals transmitted by the second communication node (300b) may be received by the antennas (314a to 314r) of the first communication node (300a). The signals received by the antennas (314a to 314r) may be provided to demodulators (DEMODs) included in the transceivers (313a to 313r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (320) may perform a MIMO detection operation on the symbols. The receiving processor (319) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (319) may be provided to a data sink (318) and a controller (316). For example, data may be provided to the data sink (318) and control information may be provided to the controller (316).

[0100] Memories (315 and 365) can store data, control information, and / or program code. Scheduler (317) can perform scheduling operations for communication. The processors (311, 312, 319, 361, 368, 369) and controllers (316, 366) illustrated in FIG. 3 may be the processor (210) illustrated in FIG. 2 and may be used to perform the methods described in the present disclosure.

[0101] FIG. 4a is a block diagram illustrating a first embodiment of a transmission path, and FIG. 4b is a block diagram illustrating a first embodiment of a reception path.

[0102] Referring to FIGS. 4A and 4B, a transmission path (410) may be implemented in a communication node that transmits a signal, and a reception path (420) may be implemented in a communication node that receives a signal. The transmission path (410) may include a channel coding and modulation block (411), an S-to-P (serial-to-parallel) block (512), an N IFFT (Inverse Fast Fourier Transform) block (413), a P-to-S (parallel-to-serial) block (414), a CP (cyclic prefix) addition block (415), and an UC (up-converter) (UC) (416). The receiving path (420) may include a DC (down-converter) (421), a CP removal block (422), an S-to-P block (423), an N FFT block (424), a P-to-S block (425), and a channel decoding and demodulation block (426). Here, N may be a natural number.

[0103] In the transmission path (410), information bits may be input to a channel coding and modulation block (411). The channel coding and modulation block (411) may perform a coding operation (e.g., a low-density parity check (LDPC) coding operation, a polar coding operation, etc.) and a modulation operation (e.g., a quadrature phase shift keying (QPSK), a quadrature amplitude modulation (QAM), etc.) on the information bits. The output of the channel coding and modulation block (411) may be a sequence of modulation symbols.

[0104] The S-to-P block (412) can convert modulation symbols in the frequency domain into parallel symbol streams to generate N parallel symbol streams. N can be an IFFT size or an FFT size. The N IFFT block (413) can perform an IFFT operation on the N parallel symbol streams to generate signals in the time domain. The P-to-S block (414) can convert the output (e.g., parallel signals) of the N IFFT block (413) into a serial signal to generate a serial signal.

[0105] The CP addition block (415) can insert a CP into a signal. The UC (416) can up-convert the frequency of the output of the CP addition block (415) to an RF (radio frequency) frequency. Additionally, the output of the CP addition block (415) can be filtered at the baseband before up-conversion.

[0106] A signal transmitted from a transmission path (410) may be input to a reception path (420). An operation in the reception path (420) may be the reverse operation of the operation in the transmission path (410). A DC (421) may down-convert the frequency of the received signal to a baseband frequency. A CP removal block (422) may remove a CP from a signal. The output of the CP removal block (422) may be a serial signal. An S-to-P block (423) may convert the serial signal into parallel signals. An N FFT block (424) may perform an FFT algorithm to generate N parallel signals. A P-to-S block (425) may convert the parallel signals into a sequence of modulation symbols. A channel decoding and demodulation block (426) may perform a demodulation operation on the modulation symbols and perform a decoding operation on the result of the demodulation operation to restore data.

[0107] In FIGS. 4A and 4B , Discrete Fourier Transform (DFT) and Inverse DFT (IDFT) may be used instead of FFT and IFFT. Each of the blocks (e.g., components) in FIGS. 4A and 4B may be implemented by at least one of hardware, software, or firmware. For example, some of the blocks in FIGS. 4A and 4B may be implemented by software, and the remaining blocks may be implemented by hardware or a “combination of hardware and software.” In FIGS. 4A and 4B , a block may be subdivided into multiple blocks, multiple blocks may be integrated into a single block, some blocks may be omitted, and blocks supporting other functions may be added.

[0108] Figure 5 is a conceptual diagram illustrating a first embodiment of a system frame in a communication system.

[0109] Referring to FIG. 5, time resources in a communication system can be divided into frame units. For example, system frames can be set consecutively in the time domain of the communication system. The length of a system frame can be 10 ms (milliseconds). The system frame number (SFN) can be set from #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.

[0110] A system frame may include two half frames. A half frame may be 5 ms long. A half frame located at the beginning of the system frame may be referred to as "half frame #0," and a half frame located at the end of the system frame may be referred to as "half frame #1." A system frame may include 10 subframes. A subframe may be 1 ms long. The 10 subframes within a system frame may be referred to as "subframes #0-9."

[0111] Figure 6 is a conceptual diagram illustrating a first embodiment of a subframe in a communication system.

[0112] Referring to FIG. 6, one subframe may include n slots, where n may be a natural number. Accordingly, one subframe may be composed of one or more slots.

[0113] Figure 7 is a conceptual diagram illustrating a first embodiment of a slot in a communication system.

[0114] Referring to Figure 7, a single slot may include one or more symbols. A single slot illustrated in Figure 7 may include 14 symbols. The length of a slot may vary depending on the number and length of symbols contained in the slot. Alternatively, the length of a slot may vary depending on the numerology.

[0115] In a communication system, the numerology applied to physical signals and channels may be variable. The numerology may be variable to meet various technical requirements of the communication system. In a communication system applying CP (cyclic prefix)-based OFDM waveform technology, the numerology may include subcarrier spacing and CP length (or CP type). Table 1 may be a first embodiment of a method for configuring a numerology for a CP-OFDM-based communication system. At least some of the numerologies in Table 1 may be supported depending on the frequency band in which the communication system operates. In addition, the communication system may additionally support numerologies not listed in Table 1.

[0116] Subcarrier spacing 15 kHz 30 kHz 60 kHz 120 kHz 240 kHz 480 kHz OFDM symbol length [μs] 66.733.316.78.34.22.1 CP length [μs] 4.762.381.190.600.300.151 Number of OFDM symbols in ms 142856112224448

[0117] When the subcarrier spacing is 15 kHz (e.g., μ=0), the slot length can be 1 ms. In this case, one system frame can contain 10 slots. When the subcarrier spacing is 30 kHz (e.g., μ=1), the slot length can be 0.5 ms. In this case, one system frame can contain 20 slots.

[0118] When the subcarrier spacing is 60 kHz (e.g., μ=2), the slot length can be 0.25 ms. In this case, one system frame can contain 40 slots. When the subcarrier spacing is 120 kHz (e.g., μ=3), the slot length can be 0.125 ms. In this case, one system frame can contain 80 slots. When the subcarrier spacing is 240 kHz (e.g., μ=4), the slot length can be 0.0625 ms. In this case, one system frame can contain 160 slots.

[0119] A symbol may be configured as a downlink (DL) symbol, a flexible (FL) symbol, or an uplink (UL) symbol. A slot consisting solely of DL symbols may be referred to as a "DL slot," a slot consisting solely of FL symbols may be referred to as an "FL slot," and a slot consisting solely of UL symbols may be referred to as a "UL slot."

[0120] 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 cell-specifically. In addition, the semi-static slot format can be additionally configured for each terminal through terminal-specific higher layer signaling (e.g., RRC signaling). The flexible symbol of the cell-specifically configured slot format can be overridden to a downlink symbol or an uplink symbol by terminal-specific higher layer signaling. In addition, the slot format can be dynamically indicated by physical layer signaling (e.g., a slot format indicator (SFI) included in DCI). The semi-statically configured slot format can be overridden by a dynamically indicated slot format. For example, the semi-statically configured flexible symbol can be overridden to a downlink symbol or an uplink symbol by the SFI.

[0121] The reference signal may be a channel state information-reference signal (CSI-RS), a sounding reference signal (SRS), a demodulation-reference signal (DM-RS), a phase tracking-reference signal (PT-RS), etc. The channel may be 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), a physical sidelink shared channel (PSSCH), etc. In the present disclosure, a control channel may mean a PDCCH, a PUCCH, or a PSCCH, and a data channel may mean a PDSCH, a PUSCH, or a PSSCH.

[0122] Figure 8 is a conceptual diagram illustrating a first embodiment of time-frequency resources in a communication system.

[0123] Referring to FIG. 8, a resource consisting of one symbol (e.g., an OFDM symbol) in the time domain and one subcarrier in the frequency domain may be defined as a "RE (resource element)". Resources consisting of one OFDM symbol in the time domain and K subcarriers in the frequency domain may be defined as a "REG (resource element group)". A REG may include K REs. A 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. In the slot illustrated in FIG. 7, N may be 14. N OFDM symbols may be used as a basic unit for resource allocation in the time domain.

[0124] In the present disclosure, RB may mean CRB (common RB). Alternatively, RB may mean PRB or VRB (virtual RB). In a communication system, CRB may mean RB that constitutes a set of consecutive RBs (e.g., a common RB grid) based on a reference frequency (e.g., point A). Carriers and / or bandwidth portions may be arranged on the common RB grid. That is, the carrier and / or bandwidth portions may be composed of CRB(s). RBs or CRBs that constitute the bandwidth portions may be referred to as PRBs, and within the bandwidth portions, the CRB index may be appropriately converted to the PRB index.

[0125] Downlink data can be transmitted via the PDSCH. The base station can transmit PDSCH configuration information (e.g., scheduling information) to the terminal via the PDCCH. The terminal can obtain the PDSCH configuration information by receiving the PDCCH (e.g., downlink control information (DCI)). For example, the PDSCH configuration information can include the MCS (modulation coding scheme) used for transmitting and receiving the PDSCH, time resource information of the PDSCH, frequency resource information of the PDSCH, feedback resource information for the PDSCH, etc. The PDSCH can refer to a radio resource through which downlink data is transmitted and received. Alternatively, the PDSCH can refer to the downlink data itself. The PDCCH can refer to a radio resource through which downlink control information (e.g., DCI) is transmitted and received. Alternatively, the PDCCH can refer to the downlink control information itself.

[0126] A terminal can perform a monitoring operation on the PDCCH to receive a PDSCH transmitted from a base station. The base station can inform the terminal of the configuration information for the PDCCH monitoring operation using a higher layer message (e.g., an RRC (radio resource control) message). The configuration information for the PDCCH monitoring operation can include CORESET (control resource set) information and search space information.

[0127] CORESET information may include PDCCH DMRS (demodulation reference signal) information, PDCCH precoding information, PDCCH occasion information, etc. The PDCCH DMRS may be a DMRS used to demodulate the PDCCH. The PDCCH occasion may be a region where the PDCCH can exist. That is, the PDCCH occasion may be a region where DCI can be transmitted. The PDCCH occasion may be referred to as a PDCCH candidate. The PDCCH occasion information may include time resource information and frequency resource information of the PDCCH occasion. In the time domain, the length of the PDCCH occasion may be indicated in symbol units. In the frequency domain, the size of the PDCCH occasion may be indicated in RB units (e.g., in PRB (physical resource block) units or CRB (common resource block) units).

[0128] The search space information may include a coreset identifier (ID) associated with the search space, a period of PDCCH monitoring, and / or an offset. Each of the PDCCH monitoring period and offset may be indicated on a slot-by-slot basis. In addition, the search space information may further include an index of the symbol at which the PDCCH monitoring operation begins.

[0129] A base station can configure a bandwidth part (BWP) for downlink communication. The BWP can be configured differently for each terminal. The base station can inform the terminal of the BWP configuration information using higher layer signaling. The higher layer signaling can mean "transmission operation of system information" and / or "transmission operation of RRC (radio resource control) message." The number of BWPs configured for one terminal can be one or more. The terminal can receive BWP configuration information from the base station and check the BWP(s) configured by the base station based on the BWP configuration information. When multiple BWPs are configured for downlink communication, the base station can activate one or more BWPs among the multiple BWPs. The base station can transmit the configuration information of the activated BWP(s) to the terminal using at least one of higher layer signaling, a medium access control (MAC) control element (CE), or DCI. The base station can perform downlink communication using the activated BWP(s). The terminal can identify the activated BWP(s) by receiving configuration information of the activated BWP(s) from the base station, and perform a downlink reception operation in the activated BWP(s).

[0130] Meanwhile, future 6G communication systems are considering deploying even larger numbers of antennas on the walls of large buildings, such as airports, shopping malls, and stadiums, to achieve additional spatial dimensions beyond the capabilities of massive MIMO systems. Systems that deploy even larger numbers of antennas over a wider area to achieve additional spatial dimensions beyond those of massive MIMO systems are defined as extra-large scale massive MIMO (XL-MIMO) systems.

[0131] XL-MIMO systems can achieve not only the high data transmission rate, low inter-device interference, and high energy efficiency that massive MIMO systems can achieve, but also spatial gains that massive MIMO systems cannot achieve by widely distributing a much larger number of antennas than massive MIMO systems. XL-MIMO systems exhibit a phenomenon in which specific terminals have different physical channel characteristics depending on their antenna regions, which is defined as channel non-stationary. Channel non-stationary can occur in both downlink and uplink. In the uplink, due to channel non-stationary, signals transmitted by terminals can be received only in specific antenna regions within the XL-MIMO system. In the downlink, due to channel non-stationary characteristics, the reference signal received power (RSRP) of a terminal exceeds the RSRP threshold only for signals transmitted from specific antenna regions among the signals transmitted by the base station.

[0132] Due to the channel non-locking phenomenon, only specific antenna regions within an XL-MIMO system can effectively transmit and receive signals during communication between a terminal and a base station. In the following description, the antenna regions for downlink (DL) and uplink (UL) where communication between a specific terminal and a base station is possible are defined as the visibility region (VR). Therefore, finding the VR for each terminal in a given environment in an XL-MIMO system can be very important.

[0133] In the 5G NR communication system, which is currently being standardized and commercialized, base stations utilize a massive MIMO system. Therefore, when a 5G NR communication system communicates with a terminal, it does not identify the antenna area for a specific terminal and provide service based on that area. In other words, the 5G NR communication system utilizes the entire antenna array of the base station to transmit and receive signals. Let's first examine the operation of the current 5G NR communication system using a massive MIMO system, as follows.

[0134] In a 5G NR communication system, a base station can transmit a channel state information reference signal (CSI-RS) for downlink (DL) channel estimation of a terminal. At this time, the base station can select a few different antenna ports from among all antenna ports to transmit the CSI-RS. Specifically, according to section 7.4.1.5 of the 3GPP TS 38.211 standard, the CSI-RS can be transmitted through specific antenna ports among multiple antennas. The antenna port p through which the CSI-RS is transmitted can be calculated as shown in Equation 1 below.

[0135]

[0136] In mathematical expression 1, s may be a sequence index determined from tables 7.4.1.5.3-2 to 7.4.1.5.3-5 of the 3GPP TS 38.211 standard, L having {1, 2, 4, 8} as elements may be a code division multiplexing (CDM) group size, and N may mean the number of CSI-RS ports.

[0137] For example, if the number of CSI-RS ports N is 8, the CDM group size L is 2, and the sequence index s has the values ​​{0, 1}, the values ​​of j can be 0, 1, 2, and 3. Therefore, the antenna port p through which the CSI-RS is transmitted can be expressed as in Equation 2 below.

[0138]

[0139] If we solve Equation 2 again, the antenna port p through which the CSI-RS is transmitted can be determined as {3000, 3001, 3002, 3003, 3004, 3005, 3006, 3007}.

[0140] The maximum number of CSI-RS antenna ports defined in the current 5G NR standard is 32. When there are two panels, up to 16 antenna ports can be used per panel, and when there are four panels, up to 8 antenna ports can be used per panel.

[0141] However, in a base station with an XL-MIMO system, if CSI-RS is transmitted by selecting some of the total antenna ports as in the current standard, the number of total antenna ports increases as the number of antennas increases. In contrast, the effective communication area with a specific terminal in an XL-MIMO system is limited to the VR. Therefore, if the base station does not transmit the CSI-RS through the correct VR, the possibility that the terminal will not receive the CSI-RS increases. As the number of antennas that make up the antenna array of the XL-MIMO system increases, the ratio of the VR of the terminal to the total antenna array decreases. Therefore, as the number of antennas that make up the antenna array of the XL-MIMO system increases, the possibility that the terminal will not receive the CSI-RS increases further. Therefore, when a base station with XL-MIMO performs communication with a terminal, it is necessary to efficiently identify the VR of the terminal in advance and allocate resources based on the identified VR.

[0142] Figure 9 is a conceptual diagram illustrating a case where a base station having XL-MIMO communicates with a terminal.

[0143] Referring to FIG. 9, a communication system may include an XL-MIMO antenna panel (910), a terminal (901), and a plurality of scatterers (920, 930, 940). The XL-MIMO antenna panel (910) or a base station having the XL-MIMO antenna panel (910) may also be referred to as an "XL-MIMO antenna system" or an "XL-MIMO system." It should be noted that the configuration of devices of the base station connected to the XL-MIMO antenna panel (910) is not illustrated in the example of FIG. 9. As described above, the XL-MIMO antenna panel (910) may be arranged on a wide wall surface such as an airport, a shopping mall, or a stadium. Each square of the XL-MIMO antenna panel (910) illustrated in FIG. 9 may be one antenna element or one small antenna panel. For convenience of explanation, the antenna element will be described below as including small antenna panels. Scatterers (920, 930, 940) may be present in the communication link between the XL-MIMO antenna panel (910) of the base station and the terminal (901). The scatterers (920, 930, 940) may be any materials that allow signals transmitted / received on the communication link between the XL-MIMO antenna panel (910) of the base station and the terminal (901) to reach the base station and / or the terminal (901) through reflection, scattering, refraction, and / or diffraction. Therefore, scatterers may be determined according to a given communication environment. For example, scatterers may include buildings, vehicles, people, structures, intelligent reflecting surfaces (IRS), reconfigurable intelligent surfaces (RIS), and / or particles in the air.

[0144] Some antenna elements (911, 912, 913) of the XL-MIMO antenna panel (910) may form a channel to the terminal (901) through the scatterers (920, 930, 940). For example, a channel may be formed between the antenna elements (911) of the first group of the XL-MIMO antenna panel (910) and the first scatterer (920) and a channel (922) between the first scatterer (920) and the terminal (901). Additionally, another channel may be formed between the second group of antenna elements (912) and the terminal (901) through a channel (931) between the second group of antenna elements (912) of the XL-MIMO antenna panel (910) and the second scatterer (930) and a channel (932) between the second scatterer (930) and the terminal (901). In addition, another channel may be formed between the third group of antenna elements (913) and the terminal (901) through a channel (931) between the third group of antenna elements (913) of the XL-MIMO antenna panel (910) and the third scatterer (940) and a channel (932) between the third scatterer (940) and the terminal (901). In this way, the number of scatterers may be interpreted as the number of valid paths existing in the communication link between the base station and the terminal.

[0145] In Fig. 9, only three different scatterers (920, 930, 940) are illustrated, but the number of scatterers may be more or less than that illustrated in Fig. 9. As illustrated in Fig. 9, a signal transmitted by a base station having an XL-MIMO antenna panel (910) can be transmitted to a terminal (901) through the scatterer(s). In addition, as illustrated in Fig. 9, a signal transmitted from a base station having an XL-MIMO antenna panel (910) to a terminal (901) is not observed evenly throughout the entire XL-MIMO antenna panel (910), but rather a phenomenon occurs in which the signal is concentrated on some antenna elements. In other words, transmission / reception of a signal to / from the terminal (901) is possible only through some antenna elements, that is, the VR defined above, in the XL-MIMO antenna panel (910).

[0146] As discussed above, the XL-MIMO antenna panel (910) has a very large number of antenna elements and communication with the terminal (901) is possible only through some of the VRs, so consideration of VRs is essential for a communication system having the XL-MIMO antenna panel (910).

[0147] The present disclosure described below will describe a method and devices for finding scatterers and scatterer-VR combinations existing in a communication link between a base station and a terminal based on VR when communicating using an XL-MIMO antenna panel. In addition, the present disclosure described below will describe a beam management method and devices for finding a base station beam and a terminal beam by forming a base station beam based on VR.

[0148] The method according to the present disclosure can perform the following three procedures for beam management. The procedure according to the present disclosure can perform beam selection between a base station and a terminal by first sensing scatterers existing between an XL-MIMO antenna panel and a terminal, second estimating VR on the XL-MIMO antenna panel for the sensed scatterers, and third forming a group of beam candidates between the XL-MIMO antenna panel and the terminal and measuring the performance.

[0149] [1]. Scatterer sensing method existing in the communication link between the base station and the terminal in the XL-MIMO system.

[0150] A method for detecting scatterers present in a communication link between a base station and a terminal in an XL-MIMO system can be composed of two sub-steps. First, a step of finding scatterer(s) present in the communication link between the base station and the terminal; second, a step of finding base station beams and terminal beams corresponding to the scatterer(s).

[0151] Figure 10 is a conceptual diagram illustrating a method for finding scatterers existing in a communication link between a base station and a terminal.

[0152] Referring to FIG. 10, a terminal (1001), a base station (1010), and scatterers (1021, 쪋, 102N) are illustrated. First, the base station (1010) may be a base station having an XL-MIMO antenna panel (not shown in FIG. 10) as described above with reference to FIG. 9. In addition to the XL-MIMO antenna panel, the base station (1010) may include all or part of the configuration described above with reference to FIG. 2, and may further include additional configurations in addition to the configurations illustrated in FIG. 2. For example, the base station (1010) may further include an interface for communicating with a core network, an interface for communicating with an adjacent base station, an interface for communicating with other communication devices connected thereto (e.g., remote transceiver device(s)), etc.

[0153] The base station (1010) can perform beam sweeping using all antenna elements (or antenna panels) of the XL-MIMO antenna panel. As illustrated in FIG. 10, when the base station (1010) performs beam sweeping using all antenna elements, it can assign a beam index to each beam. In the following description, in order to identify the base station beam, the index of the beams transmitted (or received) by the base station (1010) will be referred to as base station beam index. When the number of beams that the base station (1010) can transmit is n, the base station (1010) can sequentially transmit (or receive) by beam steepening base station beam index #1, base station beam index #2, base station beam index #3, …, base station beam index #n-1, base station beam index #n. Each of the beams transmitted by beam steepening by the base station (1010) can include base station information and / or a reference signal (RS). The signal transmitted through the base station beams may include information in a form identical or similar to the synchronization signal block (SSB) of the current 5G NR system. When the base station (1010) transmits a signal including base station information and RS to the terminal (1001), the base station (1010) may transmit the signal to the terminal (1001) using only some antenna elements or some antenna panels included in the XL-MIMO antenna panel.

[0154] The terminal (1001) has multiple antennas and can form a transmission beam and / or a reception beam using the multiple antennas. The terminal (1001) may include all or part of the configuration described in FIG. 2 above, and may further include additional configurations in addition to the configuration exemplified in FIG. 2. The terminal (1001) may further include various devices for the convenience of the user, such as various sensors (e.g., a geomagnetic sensor, an altitude sensor, etc.) and a graphical user interface (GUI).

[0155] The terminal (1001) can receive a signal transmitted by the base station (1010) through beam formation by forming a reception beam using a plurality of antennas. In addition, the terminal (1001) can transmit a signal to the base station (1010) by forming a transmission beam using a plurality of antennas. As illustrated in FIG. 10, the terminal (1001) can assign a beam index to each of the beams to identify the plurality of beams. In the following description, the index of the beams transmitted (or received) by the terminal (1001) to identify the terminal beams will be referred to as terminal beam indexes. When the number of beams that the terminal (1001) can transmit (or receive) is m, the terminal (1001) can sequentially beam sweep the beams from terminal beam index #1, terminal beam index #2, …, terminal beam index #m to transmit (or receive) a signal.

[0156] The scatterers (1021, 쪋, 102N) illustrated in Fig. 10 may exist one or more, or may not exist at all. It should be noted that the scatterers (1021, 쪋, 102N) are indicated with dotted lines to indicate that the scatterers (1021, 쪋, 102N) may or may not exist. The scatterers (1021, 쪋, 102N) may include buildings, vehicles, people, structures, IRS, RIS, and / or airborne particles, as described above in Fig. 9.

[0157] XL-MIMO systems, as exemplified in FIGS. 9 and 10, have a very large number of antenna elements. Therefore, the widely used method of transmitting signals through each antenna and determining VR based on RSRP measurement reports received from terminals may be very inefficient. This is because XL-MIMO systems have an incomparably large number of antenna elements compared to massive MIMO antennas. Therefore, in the case of XL-MIMO systems, estimating VR using the conventional method may not only take a very long time, but also greatly increase the complexity of the procedure. Therefore, in this disclosure, we propose a hierarchical VR estimation procedure capable of determining VR in XL-MIMO systems.

[0158] According to the hierarchical VR estimation process proposed in this disclosure, the entire VR estimation process can be divided into several VR estimation stages. In each VR estimation stage, the base station can receive the terminal's signal through a representative antenna among the antenna candidates, and form a group of antenna candidates for the next VR estimation stage based on the reception performance. The base station can estimate the VR by repeating this process multiple times and determining the final VR in the last VR estimation stage.

[0159] In conclusion, in the present disclosure, when performing a beam management process in a process of performing communication through an XL-MIMO system, scatterers existing in the communication link between the base station and the terminal can be found based on the beams formed by the base station and the terminal in order to select a beam in a resource-efficient manner. In addition, the base station can find a scatterer-VR combination for each scatterer(s). Thereafter, the base station selects the scatterer-VR combination with the largest RSRP among the possible scatterer-VR combinations, thereby proposing a beam management technique to find the optimal base station beam and terminal beam.

[0160] Hereinafter, based on the contents described in FIGS. 9 and 10, a procedure for sensing scatterers that may exist on a communication path with a terminal in an XL-MIMO system according to the present disclosure will be examined.

[0161] FIG. 11a is a flowchart according to a first embodiment for detecting scatterers present on a communication path between a base station and a terminal.

[0162] The terminal and base station illustrated in Fig. 11a may be the terminal and base station described previously in Figs. 9 and 10.

[0163] In step S1100, the base station can determine candidate beams for transmitting signals through the entire antenna array of the XL-MIMO antenna panel. In other words, the base station can calculate the number of candidate beams for beam sweeping using the entire antenna array of the XL-MIMO antenna panel. Since step S1100 is before scatterer sensing, the base station must form a relatively wide beam when forming a beam using the entire antenna array of the XL-MIMO antenna panel. Therefore, when forming a beam using the entire antenna array of the XL-MIMO antenna panel, the base station can use a relatively small number of beams. In describing the following embodiments, it will be explained under the assumption that the number of candidate beams for transmitting signals through the entire antenna array of the XL-MIMO antenna panel is six. However, it should be noted that this is for the convenience of understanding and is not limited thereto.

[0164] In step S1102, the base station can beam sweep each of the candidate beams determined using the entire antenna array of the XL-MIMO antenna panel and transmit the first signal to the terminal(s) through the swept beams. At this time, each of the candidate beams can be transmitted to one terminal or multiple terminals. In addition, since the candidate beams are before scatterer sensing as described above, the base station can form a relatively wide beam using the entire antenna array of the XL-MIMO antenna panel.

[0165] The first signal transmitted through each of the candidate beams may be, for example, a signal such as a synchronization signal block (SSB) used in 5G NR. If SSB is not used, the base station may set a new reference signal (RS) to perform a procedure similar to the initial beam establishment process, and may include the new RS in the first signal and transmit it. Accordingly, the first signal transmitted through each of the candidate beams may include base station information, a new RS, and base station beam index information (or a beam index value). The base station information may include information for identifying the base station. Additionally, it may be a signal known in advance between the base station and the terminal for measuring the strength of the RS received signal. In the following description of the present disclosure, both the case where a new RS is used and the case where a signal such as SSB is used will be referred to as the first signal.

[0166] The first signal may be configured with different base station beam indices for each beam to identify each of the base station beams. For example, the base station may transmit the first signal through a beam having base station beam index #1 at a first time point (or a first slot or a first symbol), may transmit the first signal through a beam having base station beam index #2 at a second time point (or a second slot or a second symbol), and may transmit the first signal through a beam having base station beam index #3 at a third time point (or a third slot or a third symbol). In this case, the base station beam index included in the first signal transmitted at the first time point may be base station beam index #1, the base station beam index included in the first signal transmitted at the second time point may be base station beam index #2, and the base station beam index included in the first signal transmitted at the third time point may be base station beam index #3. In other words, each of the first signals transmitted by beam sweeping in step S1102 may have different beam indices and otherwise include the same information. Assuming that the number of candidate beams that the base station can transmit using the entire antenna array of the XL-MIMO antenna panel is n, the base station can transmit the first signal to the terminal through beams from beam index #1 to beam index #n.

[0167] In step S1102, the terminal can receive a first signal by beam-sweeping a plurality of terminal beams. The terminal can obtain base station information, RS, and base station beam index information from the received first signal. At this time, the terminal can identify the terminal beam on which the first signal is received through the terminal beam index set by the terminal. For example, if the number of beams that the terminal can beam-sweep is m, the terminal can sequentially beam-sweep the m beams to receive the first signal transmitted by the base station. In other words, when beam-sweeping, the terminal can sequentially beam-sweep the beams from terminal beam index #1 to terminal beam index #m to receive the first signal transmitted by the base station.

[0168] In step S1104, the terminal can measure the RSRP of the RS included in the received first signal. As previously assumed, the base station sets six base station beams using the entire antenna array of the XL-MIMO antenna panel. Therefore, the base station can transmit the first signal through beams of base station beam index #1 to base station beam index #6, and the terminal can receive each of the beams of base station beam index #1 to base station beam index #6. In addition, the terminal can receive the base station beams by beam sweeping a plurality of candidate beams that the terminal can form. Therefore, the terminal can map between the base station beam and the terminal beam using the base station beam index and the terminal beam index. In addition, the measured RSRP value can be mapped for each beam pair. If it is assumed that the number of candidate beams of the terminal is six, the mapping between each beam pair and the measured RSRP value can be exemplified as shown in Table 2 below.

[0169] Base station beam index Terminal beam index RSRP measurement value Base station beam index #1 Terminal beam index #1 RSRP_106… … … Base station beam index #1 Terminal beam index #6 RSRP_45 Base station beam index #2 Terminal beam index #1 RSRP_90… … … Base station beam index #6 Terminal beam index #6 RSRP_95

[0170] Referring to Table 2, the RSRP measurement values ​​of the first signal received using the beams of terminal beam index #1 to terminal beam index #6 can be mapped for the base station beam index #1, and the case where the base station beam index #2 to base station beam index #6 are mapped in the same manner as the base station beam index #1 is exemplified. In Table 2, for convenience of explanation, it is assumed that there are 6 base station beams and 6 terminal beams. However, the number of base station beams and / or the number of terminal beams can be a larger number or a smaller number of beams. The terminal can map and store beam pairs and RSRP measurement values ​​corresponding to each beam pair as shown in Table 2.

[0171] In step S1106, the terminal can generate an RSRP report message including information as shown in Table 2 and report it to the base station. At this time, the beam through which the terminal transmits the RSRP report message can be variously used. Since the time point of transmitting the report message in step S1106 is before scatterer sensing, the terminal may not be able to determine through which beam the RSRP report message should be transmitted. Therefore, the terminal can report RSRP sequentially (by beam sweeping) through all beams that the terminal can form. As another example, the terminal can select a random beam among the beams that the terminal can form, and if a response signal to the RSRP report is not received until a certain period of time has passed after the RSRP report through the selected beam, the terminal can select a different beam and retransmit.

[0172] Meanwhile, FIG. 11a illustrates a method for transmitting RSRP measurement values ​​for a first signal via a single RSRP report message. However, the terminal may also be configured to transmit an RSRP report message every time a first signal is received or at a specific point in time after a slot in which a predetermined number of first signals are transmitted.

[0173] For example, the terminal may receive base station beam index #0 through a specific terminal beam, and transmit to the base station an RSRP value that measures an RS included in a beam corresponding to base station beam index #0 and beam pair information corresponding to the measured RSRP.

[0174] As another example, when first signals are transmitted continuously in predetermined specific slot(s) through a beam corresponding to base station beam index #0, the terminal may measure the RSRP values ​​of the first signals received in the corresponding slot(s) and, at the RSRP measurement reporting time, include the beam pairs and the RSRP values ​​corresponding to each of the beam pairs in an RSRP reporting message and transmit it to the base station.

[0175] Additionally, the present disclosure allows a terminal to report performance (e.g., beam pairs and corresponding RSRP values) for a single base station transmission beam to the base station. As another example, if the terminal supports group-based beam reporting, the terminal can simultaneously receive multiple beams from the base station. Furthermore, a terminal supporting group-based beam reporting can also perform reporting for each of the multiple beams received simultaneously.

[0176] Meanwhile, the procedures from steps S1102 to S1106 described above assume operations between a single terminal and a base station. However, multiple terminals may exist within a base station cell. Therefore, each terminal within the base station can equally apply the information shown in Table 2 or the various forms and reporting methods for RSRP reporting described above.

[0177] In step S1106, the base station can receive an RSRP report message from the terminal(s) through at least one beam among the beams formed in step S1102.

[0178] In step S1108a, the base station can determine the presence of a scatterer based on the received RSRP value. Furthermore, in step S1108b, the terminal can also determine the presence of a scatterer based on the measured RSRP value. The presence of a scatterer can be determined by comparing it with a scatterer RSRP threshold, thereby determining whether a scatterer exists on a specific path.

[0179] Therefore, the scatterer RSRP threshold may be a predetermined value to determine whether a scatterer exists. The scatterer RSRP threshold may be determined by considering the line-of-sight (LoS) path between the base station and the terminal and all additional cases in which the beam may reach. Additional cases in which the beam may reach include reflection, diffraction, and refraction. In addition, the scatterer RSRP threshold may be set by comprehensively considering the number of antennas used to transmit the reference signal, the degree of signal attenuation due to the surrounding environment, etc.

[0180] The scatterer RSRP threshold may be transmitted to the terminal in advance by the base station. For example, the scatterer RSRP threshold may be transmitted to the terminal via at least one of a system information block (SIB), downlink control information (DCI), a medium access control (MAC) control element (CE), and / or radio resource control (RRC) signaling. Alternatively, the scatterer RSRP threshold may be included in the first signal according to the present disclosure and transmitted.

[0181] Therefore, the terminal and base station can use the scatterer RSRP threshold to determine whether a scatterer is present on a specific path. If the base station fails to transmit the scatterer RSRP threshold to the terminal, step S1108b may be omitted. The dotted line indicates that step S1108b may be omitted.

[0182] Let's examine a method for determining the presence of a scatterer using the scatterer RSRP threshold. The base station can obtain the measured RSRP value corresponding to the base station beam-terminal beam pair from the RSRP measurement report message from the terminal as described in Table 2. Therefore, if the measured RSRP value is greater than the scatterer RSRP threshold, it can be determined that a scatterer is present on the path of the corresponding beam pair.

[0183] Let's look at a specific example of how to determine the presence of a scatterer. First, as assumed in Table 2, it is assumed that the base station can form six beams using all antenna elements of the XL-MIMO antenna panel, and the terminal receives the first signal from the base station using the six terminal beams. In addition, in order to identify the beams that the base station can form, it is assumed that the base station beam index #1 to base station beam index #6, and the beams that the terminal can form are assumed to be terminal beam index #1 to terminal beam index #6. This may be the same assumption as Table 2 exemplified above.

[0184] Taking base station beam index #1 as an example, the beam pairs reported from the terminal and the measured RSRP values ​​can be illustrated as follows.

[0185] (1) Base station beam index #1 - Terminal beam index #1: RSRP_#11

[0186] (2) Base station beam index #1 - Terminal beam index #2: RSRP_#12

[0187] (3) Base station beam index #1 - terminal beam index #3: RSRP_#13

[0188] (4) Base station beam index #1 - terminal beam index #4: RSRP_#14

[0189] (5) Base station beam index #1 - terminal beam index #5: RSRP_#15

[0190] (6) Base station beam index #1 - terminal beam index #6: RSRP_#16

[0191] In (1) to (6), “RSRP_#AB” can be a specific value, and in the above, ‘A’ can be identified as a base station beam index number and ‘B’ can be identified as a terminal beam index number to explain the relationship with beam pairs.

[0192] Therefore, the base station can compare and determine whether there is at least one of RSRP_#11 to RSRP_#16 that exceeds the scatterer RSRP threshold. If all of RSRP_#11 to RSRP_#16 are below the scatterer RSRP threshold, it can be determined that no scatterer exists for the base station beam index #1. On the other hand, if at least one of RSRP_#11 to RSRP_#16 exceeds the scatterer RSRP threshold, it can be determined that a scatterer exists in the path of the beam pair corresponding to the corresponding RSRP value.

[0193] Next, taking base station beam index #3 as an example, the beam pairs reported from the terminal and the measured RSRP values ​​can be illustrated as follows.

[0194] (1) Base station beam index #3 - Terminal beam index #1: RSRP_#31

[0195] (2) Base station beam index #3 - Terminal beam index #2: RSRP_#32

[0196] (3) Base station beam index #3 - Terminal beam index #3: RSRP_#33

[0197] (4) Base station beam index #3 - Terminal beam index #4: RSRP_#34

[0198] (5) Base station beam index #3 - Terminal beam index #5: RSRP_#35

[0199] (6) Base station beam index #3 - Terminal beam index #6: RSRP_#36

[0200] Similarly to the example above, the presence of a scatterer can be determined by checking whether there is an RSRP value that exceeds the scatterer RSRP threshold for base station beam index #3. In this case, there may be cases where the values ​​of RSRP_#33 and RSRP_#34 exceed the scatterer RSRP threshold. In this case, one beam pair with a higher RSRP value among RSRP_#33 and RSRP_#34 can be selected. For example, if RSRP_#34 has a value greater than RSRP_#33, the beam pair corresponding to RSRP_#34 can be selected.

[0201] Through this method, both the base station and the terminal can determine the presence of a scatterer along a specific beam pair, or in other words, a specific path. Through the above inspection, the presence of three scatterers can be illustrated in Table 3 below.

[0202] Scatterer Base Station Beam Terminal Beam Scatterer #1 Base Station Beam Index #1 Terminal Beam Index #1 Scatterer #2 Base Station Beam Index #3 Terminal Beam Index #4 Scatterer #3 Base Station Beam Index #5 Terminal Beam Index #6

[0203] According to an example in Table 3, a case is exemplified where scatterer #1 exists on the communication path between base station beam index #1 and terminal beam index #1, scatterer #2 exists on the communication path between base station beam index #3 and terminal beam index #4, and scatterer #3 exists on the communication path between base station beam index #5 and terminal beam index #6. This may be the case where the value of RSRP_#11 corresponding to the pair of base station beam index #1 and terminal beam index #1 is greater than the scatterer RSRP threshold, the value of RSRP_#34 corresponding to the pair of base station beam index #3 and terminal beam index #4 is greater than the scatterer RSRP threshold, and the value of RSRP_#56 corresponding to the pair of base station beam index #5 and terminal beam index #6 is greater than the scatterer RSRP threshold.

[0204] Meanwhile, if the base station cannot transmit the scatterer RSRP threshold value to the terminal, the base station may transmit scatterer information to the terminal in step S1110. This scatterer information may be information as shown in Table 3 above. When the base station transmits the scatterer information to the terminal, the base station may transmit the scatterer information to the terminal using at least one of the beams in which the scatterers detected in Table 3 exist or the beams in which the scatterers exist. Alternatively, the base station may transmit the scatterer information to the terminal using all beams. Step S1110 may be omitted if the base station has transmitted the scatterer RSRP threshold value to the terminal in advance as described above.

[0205] In step S1112, the terminal may transmit service information and VR-related information to the base station. The service information and / or VR-related information may be used in the hierarchical VR estimation technique in the XL-MIMO system, which will be described later in section [2], and in the beam selection procedure, which will be described later in section [3]. The service information may be, for example, information such as latency requirement information. In other words, it may include information on the sensitivity of delay time and / or service grade for the service that the terminal wishes to receive. The VR-related information may include information indicating whether the terminal supports the VR estimation process, which will be described later in the present disclosure, and information on the number of beams that the terminal can form simultaneously.

[0206] Meanwhile, the above embodiments described a case where the base station senses scatterers by transmitting RSs to the terminal via beam sweeping. However, a similar operation can also be performed where the terminal transmits RSs via uplink beam sweeping and the base station receives and determines the RSs transmitted by the terminal.

[0207] Since the base station beam utilized in the scatterer sensing process illustrated in Fig. 11a is transmitted without information about VR, a beam formation process is required through the entire antenna array. Since the XL-MIMO system has a very large number of antenna elements (or antenna arrays), the computational complexity of the process in which the base station transmits beams can be very high. Therefore, when using the XL-MIMO system in the future, it may be difficult to perform the initial beam establishment process in a way that the base station transmits SSB and the terminal receives SSB, as in the current 5G NR standard.

[0208] To address these issues, the present disclosure proposes an RSRP measurement method based on uplink transmission, rather than on downlink transmission from a base station to a terminal. In other words, the initial beam establishment procedure can be performed by the terminal transmitting an uplink beam and the base station measuring the RSRP of the uplink beam.

[0209] Figure 11b is a flowchart according to a second embodiment for detecting scatterers present on a communication path between a base station and a terminal.

[0210] The terminal and base station illustrated in Fig. 11b may be the terminal and base station described previously in Figs. 9 and 10. In this disclosure, a scatterer sensing method on a communication path between a base station and a terminal having an XL-MIMO antenna panel will be examined.

[0211] In step S1130, the terminal may generate a second signal to be transmitted to the base station. This second signal may be generated when the terminal needs to communicate with the base station. Accordingly, the terminal may be in one of the following states: initial connection with the base station, RRC idle state, or RRC inactive state.

[0212] The second signal generated by the terminal in step S1130 may include terminal information and a reference signal (RS). The terminal information may include, for example, at least one of a transmitting beam identifier or a terminal identifier. The reason for including the terminal identifier in the second signal is to enable the base station to identify the terminals, as multiple terminals may perform uplink transmission. If the second signal is transmitted exclusively for a specific terminal, the second signal may be configured not to include the terminal identifier.

[0213] The terminal identifier can be configured in various forms. For example, if the terminal is in an RRC connection state, the terminal identifier assigned by the network can be used. As another example, if the terminal is not assigned a terminal identifier by the network, the terminal's unique ID, such as all or part of the International Mobile Subscriber Identity (IMSI), can be used. As another example, if the terminal is not assigned a terminal identifier by the network, the terminal can randomly select a portion of a preset sequence and identify the terminal through the selected sequence. In this way, if a portion of a sequence that can be commonly used by terminals is used, a collision resolution procedure that takes into account collisions with other terminals may be additionally required. In addition, the present disclosure does not place any particular restrictions on other methods for identifying the terminal.

[0214] In step S1132, the terminal can transmit the second signal in the uplink through multiple beams in a beam sweeping manner. As previously discussed in FIG. 11a, the second signal transmitted in the uplink can be set to have a different beam identifier for identifying the transmitted beam. In step S1132, the base station can receive the second signal in the beam sweeping manner or through a specific beam. In this case, the base station can receive the beam by beam sweeping using the entire antenna array of the XL-MIMO antenna panel. Therefore, in the case of FIG. 11a, the base station beam swept for the first signal transmission, but in the case of FIG. 11b, the base station can beam sweep for the second signal reception.

[0215] In step S1134, the base station can obtain RSRP by measuring the RS included in the second signal received from the terminal. At this time, the base station can map and store beam pairs in the form of Table 2 described above and the measured RSRP value corresponding to each beam pair.

[0216] In step S1136, the base station can compare the measured RSRP value with the scatterer RSRP threshold, and find the terminal beam(s) that exceed the scatterer RSRP threshold. At this time, the terminal beam index of the terminal can be interpreted as playing a similar role to the SSB index used in the SSB-based initial beam establishment process used in the 5G NR standard. The base station can obtain beam pair information that exceeds the scatterer RSRP threshold. Since this procedure can be performed in the same manner as the scatterer acquisition procedure of Table 3 described above in FIG. 11a, a duplicate description will be omitted. In other words, the base station can obtain scatterer information and its corresponding beam pair information as in Table 3.

[0217] In step S1138, the base station may transmit the acquired scatterer information as shown in Table 3 to the terminal. At this time, the base station beam information among the scatterer information may not be needed by the terminal. If the base station beam information is not needed, only the terminal beam indices and the RSRP values ​​measured at the base station corresponding to each index may be transmitted as scatterer information without the base station beam index among the scatterer information. In addition, the terminal may not need the RSRP values ​​measured at the base station. In this case, the scatterer information of FIG. 11b may be simply composed of the terminal beam index. In addition, the beam through which the scatterer information is transmitted may be beam-swept using the entire antenna array of the XL-MIMO antenna panel, or may utilize at least one beam among the beams acquired as shown in Table 3.

[0218] In step S1138, the terminal can receive scatterer information from the base station. Based on the scatterer information received from the base station, the terminal can confirm that three scatterers exist in the communication path between the base station and the terminal, and can confirm the terminal beam and base station beam corresponding to each scatterer.

[0219] In step S1140, the terminal may transmit service information and VR-related information to the base station. The service information and / or VR-related information may be the same information as described in step S1112 of FIG. 11a. In other words, it may be used in the hierarchical VR estimation technique in the XL-MIMO system, which will be described later in section [2], and in the beam selection procedure, which will be described later in section [3]. The service information may be, for example, information such as latency requirement information. In other words, it may include information on the sensitivity of delay time and / or service grade information for the service that the terminal wishes to receive. The VR-related information may include information indicating whether the terminal supports the VR estimation process, which will be described later in the present disclosure, and information on the number of beams that the terminal can form simultaneously.

[0220] [2]. Hierarchical VR estimation method

[0221] In the hierarchical VR estimation technique in the XL-MIMO system, the VR corresponding to each scatterer can be estimated based on the scatterer information identified in the scatterer sensing process existing in the communication link between the base station and the terminal in the XL-MIMO system.

[0222] Before performing the VR estimation process, the base station may receive information from the terminal, such as delay requirement information and / or whether the VR estimation process is supported. Information such as delay requirement information and / or whether the VR estimation process is supported may be performed as described in the last step of Section [1], or may be performed in the first step of the hierarchical VR estimation method described in Section [2].

[0223] Figure 12a is a flowchart of part of the operation for hierarchical VR estimation at a base station, and Figure 12b is a flowchart of the remaining operation for hierarchical VR estimation at a base station.

[0224] Figures 12a and 12b illustrate the operation of a base station. When the base station transmits a specific signal (or message or information) to a terminal, the terminal can receive the signal (or message or information) transmitted by the base station. Furthermore, when the base station receives a specific signal (or message or information) from a terminal, the terminal can generate a specific signal and transmit it to the base station.

[0225] In step S1200, the base station can determine whether the terminal supports VR estimation based on the service information and / or VR-related information received in step S1112 described in FIG. 11a of section [1] above, or based on the service information and / or VR-related information received in step S1140 described in FIG. 11b. If the terminal supports VR estimation, the base station can perform step S1220, and if the terminal does not support VR estimation, the base station can perform step S1210.

[0226] In step S1210, the base station may determine to perform a defined operation for a terminal that does not support VR estimation, and may perform an instruction according to the determined operation. The base station may transmit a signal including operation instruction information for a terminal that does not support VR estimation to the terminal. For example, the instruction information may include information for restricting communication with the XL-MIMO system for a terminal that does not support VR estimation. As another example, the instruction information may indicate a beam that the base station that does not support VR estimation has randomly allocated in advance. The reason why the base station assigns a random beam that it has previously set is because the consumption of communication resources is very high when performing a beam management process with a terminal that does not support VR estimation. Therefore, in order to avoid performing such an inefficient beam management process, the terminal that does not support VR estimation may be instructed to a preset beam.

[0227] Step S1220 can be performed if the terminal supports VR estimation. Therefore, the base station can determine the number of steps in the hierarchical estimation process by synthesizing information received from the terminal in step S1220, such as the terminal's delay requirement information and the number of antenna ports capable of simultaneous transmission and reception at the base station. Let's examine an example of how the factors used by the base station to determine the VR estimation steps are used.

[0228] The base station can determine the number of VR estimation steps based on the delay requirements of the terminal. If the delay requirements of the terminal are short, the base station should perform VR estimation quickly when the terminal requires a short delay. Therefore, the base station can set a smaller number of VR estimation steps. As another example, the fewer antenna ports the base station can simultaneously transmit and receive, the fewer representative antennas of VR candidates that can simultaneously transmit and receive in each VR estimation step. Therefore, the base station can set a larger number of steps in the VR estimation process by segmenting the number of antenna ports the base station can simultaneously transmit and receive. The base station can determine the VR estimation steps by comprehensively assessing these factors.

[0229] The number of steps in the VR estimation process determined based on the method described above can be exemplified as shown in Table 4 below.

[0230] Whether the VR estimation process is supported? Number of TrueVR estimation process steps 2

[0231] In step S1220, the base station can transmit information on the number of steps in the hierarchical estimation process to the terminal as shown in Table 4. At this time, the information on the number of steps in the hierarchical estimation process can be transmitted to the terminal via SIB, DCI, or RRC signaling.

[0232] The terminal can receive information on the number of steps of the hierarchical estimation process as shown in Table 4 from the base station. If information as shown in Table 4 is transmitted and "Whether VR estimation process is supported" is true, the "number of VR estimation process steps" may be valid. On the other hand, if "Whether VR estimation process is supported" is false, the "number of VR estimation process steps" may be ignored even if it is included. If the standard pre-defines that the information on the number of VR estimation process steps is transmitted only when the VR estimation process is supported, the information on whether VR estimation process is supported as shown in Table 4 may not be included. The terminal can check the VR estimation step by receiving a message as shown in Table 4 or simply including only the information on the number of VR estimation process steps.

[0233] Meanwhile, the base station can dynamically change the number of steps in the VR estimation process depending on the total amount of traffic generated when communicating with the terminal. If the base station wants to dynamically change the number of steps in the VR estimation process, it can do so by actively instructing the number of steps in the VR estimation process in the DCI format, or by dynamically setting the number of steps within the maximum number of VR estimation process steps supported by the terminal through MAC-CE or RRC signaling.

[0234] For convenience of explanation, below, we assume that VR estimation is performed in two stages, as shown in Table 4.

[0235] In step S1222, the base station can determine the scatterers on which VR estimation will be performed. In the following description, it will be assumed that three scatterers are detected in the scatterer sensing procedure as described above in Table 3. However, the method described below can also be applied in the same manner when the number of scatterers detected in the scatterer sensing procedure is two or four or more. In addition, in the following description, it is assumed that VR estimation for the scatterers is performed in the order of scatterer #1, scatterer #2, and scatterer #3. However, since the terminal does not know which scatterer to perform VR estimation on first, the base station can transmit to the terminal information on the scatterers on which VR estimation will be performed in step S1222. If the number of scatterers detected in the scatterer sensing procedure is one, step S1222 may be omitted.

[0236] In the example of Fig. 12, the number of steps of the hierarchical estimation process and the scatterer information are transmitted to the terminal in steps S1220 and S1222, respectively. However, the number of steps of the hierarchical estimation process and the scatterer information may also be transmitted from the base station to the terminal all at once.

[0237] In step S1224, the base station may set the VR estimation step (p) to 1. This may be a step set to distinguish that the estimation step is the first step.

[0238] In step S1226, the base station may divide the antenna region to receive a signal from the terminal in the VR estimation step #p, and select a representative antenna from each of the divided antenna regions. In step S1226, if the base station performs VR estimation for the first time, it may be VR estimation step #1. VR estimation step #1 may be the first procedure for VR estimation after the base station performs scatterer sensing as shown in FIG. 11a or FIG. 11b. Accordingly, the entire antenna of the XL-MIMO antenna panel, which is the base station, may be divided into a predetermined number of regions. And a representative antenna may be selected for each divided antenna region. The representative antenna may be a single antenna element or a small antenna panel.

[0239] In the VR estimation step #1, let us examine the case where the entire antenna of the XL-MIMO antenna panel is divided into a predetermined number of regions with reference to the attached drawing.

[0240] Figure 13a is a conceptual diagram for explaining the division of antenna areas in the entire antenna array of an XL-MIMO antenna panel and the representative antenna settings for each area.

[0241] Referring to Fig. 13a, the entire antenna array (1300) of the XL-MIMO antenna panel is illustrated. According to the example of Fig. 13a, the entire antenna array (1300) is illustrated as being divided into six regions: a first region (1310), a second region (1320), a third region (1330), a fourth region (1340), a fifth region (1350), and a sixth region (1360). In addition, each region (1310-1360) is illustrated as being composed of 25 antennas (or antenna panels).

[0242] The entire antenna array (1300) of the XL-MIMO antenna panel illustrated in FIG. 13a is, as previously described, positioned on walls in stadiums, shopping malls, and the like, and thus actually consists of a very large number of antenna elements. Accordingly, the six areas illustrated in FIG. 13a may also be quite large areas.

[0243] Each of the regions (1310, 1320, 1330, 1340, 1350, 1360) illustrated in FIG. 13a may be a case where the entire antenna array (1300) of the XL-MIMO antenna panel is divided into upper and lower halves, and the upper region is divided into three equal parts, a first region (1310), a second region (1320), and a third region (1330), and the lower region is divided into three equal parts, a fourth region (1340), a fifth region (1350), and a sixth region (1360). In FIG. 13a, for the convenience of explanation, a case where the region is divided into six regions is illustrated, but the region may be divided into a greater number of regions or a smaller number of regions. In addition, the method of dividing the regions illustrated in FIG. 13a is only one example, and the present disclosure is not limited thereto.

[0244] In step S1226, the base station can select representative antennas (1311, 1321, 1331, 1341, 1351, 1361) for each of the divided areas (1310-1360). In the example of Fig. 13a, an antenna located at the center of each area is selected. However, the representative antenna can be set in various ways, such as the first antenna from the top left, the first antenna from the top right, or an arbitrary antenna, rather than the center of each area.

[0245] In step S1228, the base station may instruct the terminal to transmit a reference signal (RS). The RS signal transmission instruction may be transmitted to the terminal via upper layer signaling dedicated to the terminal. The RS signal transmission instruction may include RS transmission timing and period information, and may indicate which beams to use. Looking into this in more detail using Table 3 described above, in the case of the VR estimation step for scatterer #1, the beam that the terminal should use should be the beam of terminal beam index #1, in the case of the VR estimation step for scatterer #2, the beam that the terminal should use should be the beam of terminal beam index #4, and in the case of the VR estimation for scatterer #3, the beam that the terminal should use should be the beam of terminal beam index #6. The base station may transmit this information to the terminal via upper layer signaling. The base station may transmit upper layer signaling for each scatterer measurement, or may include all information such as the period at which RS should be transmitted for VR measurement for all scatterers, the transmission timing, the total number of transmissions, and the beam index to be used.

[0246] As another example, RS signal transmission instructions may be sent via DCI whenever RS ​​reception is required from a terminal. In this case, the DCI may indicate the beam index (or scatterer information) to be used by the terminal and the transmission time point. If higher-layer signaling indicates that RSs should be transmitted at regular intervals, they may be transmitted separately at specific times.

[0247] In step S1230, the base station can receive the RS transmitted by the terminal via the representative antennas. The RS received from the terminal may be a sounding reference signal (SRS). Alternatively, the RS received from the terminal may be a newly defined RS for VR estimation by the terminal to the base station according to the present disclosure. The present disclosure does not impose any specific restrictions on the type of RS used.

[0248] Additionally, the base station can measure the RSRP for the received RS. The RSRP values ​​measured for each representative antenna at the base station can be mapped to the received antenna and stored in memory. An example of the mapping between each representative antenna and the measured RSRP values ​​is illustrated in Table 5 below.

[0249] Representative antenna RSRP measurements for VR candidate #1A #1-1RSRP_35A #1-2RSRP_62A #1-3RSRP_69A #1-4RSRP_65A #1-5RSRP_85A #1-6RSRP_97

[0250] In Table 5, VR candidate #1 can be, for example, a candidate for the VR path corresponding to scatterer #1. In addition, in Table 5, A #1-1 may be a representative antenna (1311) of the first region (1310) described above in FIG. 13a, A #1-2 may be a representative antenna (1321) of the second region (1320) described above in FIG. 13a, A #1-3 may be a representative antenna (1331) of the third region (1330) described above in FIG. 13a, A #1-4 may be a representative antenna (1341) of the fourth region (1340) described above in FIG. 13a, A #1-5 may be a representative antenna (1351) of the fifth region (1350) described above in FIG. 13a, and A #1-6 may be a representative antenna (1361) of the sixth region (1360) described above in FIG. 13a.

[0251] The RSRP values ​​measured at each representative antenna for each area can be mapped with the corresponding antenna and stored as shown in Table 5.

[0252] In step S1232, the base station can compare the RSRP values ​​measured for each representative antenna with a preset threshold. In the following description, for convenience of explanation, the preset threshold will be referred to as the "first-stage threshold for VR estimation." As previously explained, VR estimation can be performed through one or more stages. Therefore, thresholds for VR estimation can be set for each stage. The thresholds set for each stage can have the same or different values. In addition, the scatterer RSRP threshold described in the procedure for scatterer sensing above can have the same or different values ​​from the thresholds for each stage.

[0253] Through comparison, the base station can identify representative antennas with RSRP values ​​greater than the first-stage threshold for VR estimation. Therefore, the base station can determine antenna regions with values ​​greater than the first-stage threshold for VR estimation. The representative antennas and threshold values ​​determined based on the measured RSRP values, as shown in Table 5, are exemplified in Table 6 below.

[0254] First-stage threshold for VR estimation RSRP_80 First-stage VR candidate representative antenna(s) exceeding the first-stage threshold for VR estimation A #1-5, A #1-6

[0255] According to Table 6, the first-stage threshold for VR estimation is set to RSRP_80. In general, the first-stage threshold may require a higher RSRP than the scatterer RSRP threshold described above.

[0256] A base station that has acquired first-stage VR candidate representative antennas exceeding the first-stage threshold for VR estimation, as shown in Table 6, can set all antennas in the area(s) containing the corresponding representative antennas as VR candidate antennas. This is illustrated below with reference to Figure 13a.

[0257] According to FIG. 13a, representative antennas (1311, 1321, 1331, 1341, 1351, 1361) are selected from each of the first region (1310) to the sixth region (1360), and according to Table 6, the representative antenna (1351) of the fifth region (1350) and the representative antenna (1361) of the sixth region (1360) may be antennas having an RSRP value greater than or equal to the first-stage threshold for VR estimation. Therefore, the base station may set the VR candidate first region (1370) including the fifth region (1350) and the sixth region (1360) as a region for the second-stage VR estimation in step S1232.

[0258] In step S1234, the base station can determine whether the current VR estimation step (p) is equal to the number of steps (P) of the hierarchical estimation process determined in step 1220. If the determination result in step S1234 determines that the current VR estimation step (p) is not equal to the number of steps (P) of the hierarchical estimation process determined in step 1220, this may mean that additional VR estimation needs to be performed. Therefore, if additional VR estimation needs to be performed, the base station can proceed to step S1236, and if the current VR estimation step (p) is equal to the number of steps (P) of the hierarchical estimation process determined in step 1220, the base station can proceed to step S1240.

[0259] When proceeding to step S1236, the base station can increase the p value by 1 and proceed to step S1226. Since the initial p value is set to 1, the p value can be set to 2 in the second VR estimation step.

[0260] If VR estimation is performed only once, rather than two or more times, the base station may set the VR candidate first area (1370) as a VR area in step S1240. Since this disclosure assumes that the VR estimation step is performed in two steps, we will first examine the case where the VR estimation step proceeds to step S1226.

[0261] In step S1226, the base station can redistribute antenna areas for RS reception to perform the second stage of VR estimation and select a representative antenna for each area. This will be examined with reference to Figure 13b.

[0262] Figure 13b is a conceptual diagram illustrating the procedure for dividing the antenna array and selecting a representative antenna in the second stage of VR estimation.

[0263] The antenna array illustrated in Fig. 13b may be the VR candidate first region (1370) estimated in the VR estimation step 1 above. Accordingly, the VR candidate first region (1370) may be divided into multiple antenna regions, and a representative antenna may be set for each divided antenna region.

[0264] Referring to FIG. 13B, dividing dotted lines for dividing a VR candidate first region (1370) are illustrated. The first dividing dotted line (1381) and the second dividing dotted line (1382) may be dividing dotted lines for dividing the VR candidate first region (1370) into three equal parts along the vertical axis. In addition, the third dividing dotted line (1391) and the fourth dividing dotted line (1392) may be dividing dotted lines for dividing the VR candidate first region (1370) into two equal parts along the horizontal axis. The base station may further divide the VR candidate first region (1370) into six sub-regions based on criteria such as the dividing lines (1381-1384).

[0265] For example, the VR candidate first region (1370) may be composed of a 2-1 region consisting of nine antennas (or antenna panels) with the first representative antenna (1371) as the center, a 2-2 region consisting of nine antennas (or antenna panels) with the second representative antenna (1372) as the center, a 2-3 region consisting of nine antennas (or antenna panels) with the third representative antenna (1373) as the center, a 2-4 region consisting of nine antennas (or antenna panels) with the fourth representative antenna (1374) as the center, a 2-5 region consisting of nine antennas (or antenna panels) with the fifth representative antenna (1375) as the center, and a 2-6 region consisting of nine antennas (or antenna panels) with the sixth representative antenna (1376) as the center.

[0266] Then, there may be some overlapping antennas (1370a, 1370b, 1370c) along the third dividing dotted line (1383) and the fourth dividing dotted line (1384). In other words, the antennas (1370a, 1370b, 1370c) may be included in both the 2-1 region and the 2-4 region. Antennas that may be simultaneously included in different regions should not be selected as representative antennas.

[0267] In this disclosure, as shown in Fig. 13b, the VR candidate first region (1370) is divided into six sub-regions again, and a representative antenna for each sub-region is selected.

[0268] At step S1228, the base station can instruct the terminal to transmit an RS. At this time, the base station can instruct the terminal to transmit an RS via terminal beam index #1, as this is a procedure to identify a VR by distinguishing the detailed antenna area for scatterer #1. Furthermore, since the RS transmission instruction method has been previously explained, a detailed explanation will be omitted.

[0269] Therefore, the terminal can transmit an RS through the terminal beam index #1 to detect scatterer #1 based on the RS transmission instruction from the base station. The RS transmitted by the terminal may be an SRS as described above, or another RS.

[0270] In step S1230, the base station can receive the RS transmitted by the terminal using the representative antennas (1371-1376) and measure the RSRP for each RS received through each representative antenna. The RSRP values ​​received using each representative antenna (1371-1376) in the VR estimation step 2 can be exemplified as shown in Table 7 below.

[0271] Representative antenna RSRP measurements for VR candidate #2 A #2-1RSRP_48A #2-2RSRP_92A #2-3RSRP_73… … A #2-6RSRP_59

[0272] In Table 7, the representative antennas of VR candidate #2 may be representative antennas of the detailed antenna areas for scatterer #1 in the second stage of VR estimation, as described in Fig. 13b. Therefore, as illustrated in Table 7, the RSRP values ​​measured at each representative antenna for each detailed antenna area may be mapped with the corresponding antenna and stored as shown in Table 7.

[0273] Thereafter, the base station can compare the RSRP values ​​measured at each of the representative antennas for each detailed antenna area with a threshold value in step S1232. In the following description, for convenience of explanation, the threshold value for comparison with the RSRP values ​​measured at each of the representative antennas for each detailed antenna area will be referred to as a “second-stage threshold value for VR estimation.” The second-stage threshold value for VR estimation may be an RSRP value greater than the first-stage threshold value for VR estimation described above. As another example, the second-stage threshold value may use the same threshold value as the first-stage threshold value for VR estimation described above.

[0274] Through comparison, the base station can identify representative antennas with RSRP values ​​greater than the second-stage threshold for VR estimation. Therefore, the base station can determine antenna regions with values ​​greater than the second-stage threshold for VR estimation. The representative antennas and threshold values ​​determined based on the measured RSRP values, as shown in Table 7, are exemplified in Table 8 below.

[0275] Second-stage threshold for VR estimation RSRP_90 Second-stage VR candidate representative antenna(s) exceeding the second-stage threshold for VR estimation A #2-2, A #2-5

[0276] According to Table 8, the second-stage threshold for VR estimation is exemplified when RSRP_90 is set. Typically, the second-stage threshold may require a higher RSRP than the first-stage threshold described above.

[0277] A base station that has acquired second-stage VR candidate representative antennas exceeding the second-stage threshold for VR estimation, as shown in Table 8, can set all antennas in the area(s) containing the corresponding representative antennas as VR candidate antennas. This is illustrated below with reference to Figure 13b.

[0278] Referring to the example of Table 8 with reference to FIG. 13b, the representative antenna (1372) of the 2-2 region and the representative antenna (1375) of the 2-5 region can be representative antennas that exceed the second-stage threshold for VR estimation. In FIG. 13b, the 2-2 region and the 2-5 region, which include representative antennas that exceed the second-stage threshold for VR estimation, can be VR candidate second regions. The VR candidate second region can be a VR candidate region determined as a result of performing the second-stage VR estimation.

[0279] After determining the second-stage VR candidate area in this way, the base station can proceed to step S1234. In step S1234, the base station can determine whether the current VR estimation step (p) is equal to the number of steps (P) of the hierarchical estimation process determined in step 1220. If the result of the determination in step S1234 determines that the current VR estimation step (p) is not equal to the number of steps (P) of the hierarchical estimation process determined in step 1220, this may mean that additional VR estimation needs to be performed. Therefore, if additional VR estimation needs to be performed, the base station can proceed to step S1236, and if the current VR estimation step (p) is equal to the number of steps (P) of the hierarchical estimation process determined in step 1220, the base station can proceed to step S1240.

[0280] In the embodiment of the present disclosure, since a two-step procedure is assumed, and since the second VR estimation has been performed so far (p = 2), the base station can proceed to step S1240. In step S1240, the base station can set the second VR candidate region as the VR region. The determined VR region may be the VR region for scatterer #1. For convenience of explanation, this will be referred to as the "VR region of scatterer #1" hereinafter.

[0281] As described above, when performing VR estimation step 1 and VR estimation step 2, the first VR candidate region (1370) can be found from the entire antenna array of the XL-MIMO antenna in VR estimation step 1. Therefore, when performing VR estimation step 1, the antennas that can be used when selecting a VR region for communicating with the terminal can select an antenna region that is narrower than the entire antenna array of the XL-MIMO antenna. In addition, when performing VR estimation step 2, the second VR candidate antenna regions (region 2-2 and region 2-5) that are narrower than the first VR antenna candidate region (1370) can be found. Therefore, the more VR estimation steps are performed, the more detailed antenna candidate regions can be found.

[0282] As the VR estimation steps are repeated, the number of antennas in the same group as the representative antenna in the VR candidate region decreases, and accordingly, the average distance between one antenna in the same group and the representative antenna becomes closer. The closer the distance between two different antennas, the less the influence of channel non-locking, and thus the more similar the performance of the representative antenna will be to the performance of other antennas in the group. Therefore, the representative antenna can be considered to represent the group more accurately. In the hierarchical VR estimation process, since the nth stage of VR estimation is based on the results of the n-1th stage of VR estimation, the base station can measure performance in a narrower VR region with greater precision.

[0283] After step S1240, the base station can check whether the VR determination of all scatterers has been completed in step S1250. If the VR determination of all scatterers has been completed, the base station can terminate the flowcharts of FIGS. 12a and 12b. On the other hand, if the VR determination of all scatterers has not been completed, the base station can proceed to step S1260.

[0284] In step S1260, the base station may select the next scatterer for which the VR has not been determined. The base station may then proceed to step S1222 and perform a stepwise procedure for determining the VR for the corresponding scatterer. Since the number of steps in the hierarchical estimation process determined in step S1220 must be applied equally to all scatterers, the base station may perform step S1222 after step S1260.

[0285] Based on the method described above, the base station can find the VR area for all scatterers from scatterer #1 to scatterer #3 in the same way. When finding the VR area for scatterer #2, the terminal transmits the RS through the terminal beam index #4, and when finding the VR area for scatterer #3, the terminal transmits the RS through the terminal beam index #6. Otherwise, the VR area for each scatterer can be found through the same procedure as the procedure for finding scatterer #1 above. The VR area for each scatterer can be determined as shown in Table 9 below.

[0286] Scatterer VR Scatterer #1VR #1Scatterer #2VR #2Scatterer #3VR #3

[0287] The VR found in this way can be understood as follows with reference to FIG. 9 described above. Scatterer #1 can correspond to the first scatterer (920) of FIG. 9, scatterer #2 can correspond to the second scatterer (930) of FIG. 9, and scatterer #3 can correspond to the third scatterer (940) of FIG. 9.

[0288] The VRs corresponding to each of the scatterers may be the first group antenna elements (911), the second group antenna elements (912), and the third group antenna elements (913) of FIG. 9. In other words, VR #1 corresponding to scatterer #1 may be the first group antenna elements (911), VR #2 corresponding to scatterer #2 may be the second group antenna elements (912), and VR #3 corresponding to scatterer #3 may be the third group antenna elements (913).

[0289] The embodiments described above describe a case where three communication links exist between a terminal and a base station, each with three scatterers. However, the number of scatterers can be two or fewer, or four or more. Even in these cases, the VR for each scatterer can be determined in the same manner based on the above-described method.

[0290] The VRs described in the embodiment of FIG. 9 exemplify a case where VR #1, VR #2, and VR #3 do not overlap. However, during the VR estimation process, a situation may arise where two or more different VRs overlap, depending on the position of the representative antenna and the RSRP measurement value.

[0291] In addition, in the procedure for determining the combination of each scatterer and VR as shown in Table 9 in the above description, an example is shown in which each VR area is configured to have the same size as illustrated in Fig. 9. However, the sizes of VR #1, VR #2, and VR #3 may be set differently.

[0292] If VRs #1, #2, and #3 are all sized identically, the base station can determine the scatterer-VR combination while also considering antenna efficiency when selecting a VR. Conversely, if VRs #1, #2, and #3 are sized differently, there are no restrictions on the number of antennas per VR, allowing the base station to select the scatterer-VR combination that maximizes communication efficiency through the scatterer.

[0293] On the other hand, the VR estimation steps described above describe a procedure in which a base station measures a reference signal transmitted through a terminal beam and estimates VR based on reception performance. However, if a procedure in which a base station transmits a reference signal and a terminal measures and reports the reference signal is used, the procedure can also be performed in the same manner as described above. However, if the terminal measures the reference signal, an additional procedure for reporting information about the measured reference signal to the base station is required, and since the procedure for VR estimation is performed at the terminal, the performance and complexity of the terminal may increase. In addition, if the base station transmits the reference signal and the terminal performs the VR estimation step, the base station can transmit the reference signal using a narrower beam than the terminal, which has the advantage of allowing a more detailed setting of the VR area.

[0294] [3]. Method for selecting base station beam and terminal beam in XL-MIMO system

[0295] Based on the above description, after finding the VR region(s), the beam(s) to be used for actual communication between the base station and the terminal can be selected. The present disclosure, described below, will examine the procedure for selecting a base station beam and terminal beam pair to be used for communication in the VR region(s).

[0296] FIG. 14a is a flowchart of a portion of an operation for selecting a base station beam and a terminal beam in a communication system using an XL-MIMO antenna, and FIG. 14b is a flowchart of the remaining operations for selecting a base station beam and a terminal beam in a communication system using an XL-MIMO antenna.

[0297] Figures 14a and 14b illustrate the operation of a base station. When the base station transmits a specific signal (or message or information) to a terminal, the terminal can receive the signal (or message or information) transmitted by the base station. Furthermore, when the base station receives a specific signal (or message or information) from a terminal, the terminal can generate a specific signal and transmit it to the base station.

[0298] In step S1400, the base station can select one of the scatterer-VR combinations as previously discussed in Table 9. For example, one of the combinations of scatterer #1-VR #1, scatterer #2-VR #2, or scatterer #3-VR #3 can be selected. In the present disclosure, for the sake of convenience of explanation, it is assumed that the combination of scatterer #1-VR #1 is selected. The selection of the combination of scatterer #1-VR #1 can be understood in the same way as the selection of the base station beam index #1 and the terminal beam index #1 according to the example of Table 3 above.

[0299] In step S1402, the base station can transmit to the terminal the UE beam index and RS transmission instruction corresponding to the selected combination. This RS transmission instruction can be based on upper layer signaling so that all UE beams are transmitted sequentially at once, or can be separately instructed to transmit RS before the corresponding time for each UE beam index using DCI. The example of Fig. 14a illustrates a case where the instruction is transmitted at each time when RS transmission is required using DCI. In addition, the RS that the base station instructs the terminal to transmit can be, for example, an SRS or a separately defined RS.

[0300] When the base station instructs the terminal to transmit RS using a specific beam index, the terminal can transmit RS using the beam at a time when uplink transmission is permitted. In step S1404, the base station can receive the RS transmitted by the terminal, measure the RSRP, and store it. At this time, the storage method can store the RSRP measurement value by mapping it to the scatterer-VR combination.

[0301] At step S1406, the base station can check whether RSRP measurements of all scatterer-VR combinations have been completed. If RSRP measurements of all scatterer-VR combinations have been completed, the base station can proceed to step S1410. If RSRP measurements of all scatterer-VR combinations have not been completed, the base station can proceed to step S1408.

[0302] In step S1408, the base station may select a scatterer-VR combination for which RSRP measurement has not yet been completed. The base station may then proceed again from step S1402.

[0303] Based on the method described above, the RSRP values ​​measured for each scatterer-VR combination can be exemplified in a table as shown in Table 10 below.

[0304] Scatter-VR combination terminal beam RSRP measurements Scatter #1-VR #1 terminal beam index #1RSRP_109 Scatter #2-VR #2 terminal beam index #4RSRP_110 Scatter #3-VR #3 terminal beam index #6RSRP_96

[0305] The example in Table 10 illustrates a case where the base station and terminal measure the performance of three scatterer-VR combinations and map and store the RSRP measurement values ​​corresponding to each scatterer-VR combination. The results in Table 10 can be interpreted as follows.

[0306] The combination of scatterer #1-VR #1 can be understood as the combination of terminal beam index #1-VR #1, the combination of scatterer #2-VR #2 can be understood as the combination of terminal beam index #4-VR #2, and the combination of scatterer #3-VR #3 can be understood as the combination of terminal beam index #6-VR #3.

[0307] According to Table 10, the terminal can transmit an RS to the base station using the terminal beam corresponding to the terminal beam index #1, and the base station can receive the beam corresponding to the terminal beam index #1 through VR #1. Then, the base station can measure the RSRP of the RS transmitted through the terminal beam corresponding to the terminal beam index #1 using VR #1. In the same manner, the terminal can transmit an RS to the base station using the terminal beam corresponding to the terminal beam index #4, and the base station can receive the beam corresponding to the terminal beam index #4 through VR #2. Then, the base station can measure the RSRP of the RS transmitted through the terminal beam corresponding to the terminal beam index #4 using VR #2. The form corresponding to the terminal beam index #6 can be understood in the same way.

[0308] In step S1410, the base station may select scatterers based on the number of scatterers to be selected and the measured RSRP. At this time, if the number of scatterers to be selected is 1, the base station may select the scatterer with the highest RSRP value among the scatterers. According to the example in Table 10, if only one scatterer is selected, the base station may select scatterer #2. If the number of scatterers to be selected is 2, the base station may sequentially select 2 scatterers from among the scatterers starting from the scatterer with the highest RSRP value. According to the example in Table 10, if 2 scatterers are selected, the base station may sequentially select scatterer #2 and scatterer #1.

[0309] Meanwhile, when determining the number of scatterers to be selected, the base station may consider the traffic volume of the base station and the number of beams that the terminal can form simultaneously. At this time, information on the number of beams that the terminal can form simultaneously may be received and included in the VR-related information described in Section [1]. As another example, information on the number of beams that the terminal can form simultaneously may be transmitted through uplink control information (UCI) that the terminal transmits to the base station. As another example, a message transmitted when the terminal performs a random access (RA) procedure to the base station may be utilized. For example, when the terminal performs a 4-step RA procedure, information on the number of beams that the terminal can form simultaneously may be included in the first message (massage 1, Msg1) transmitted to the base station, or may be included in message A (massage A, MsgA) transmitted to the base station when the terminal performs a 2-step RA procedure. As another example, information on the number of beams that a terminal can form simultaneously may be transmitted by being included in UE Assistance Information transmitted by the terminal to the base station, or may be transmitted by being included in upper layer signaling (e.g., RRC signaling).

[0310] In step S1412, the base station may transmit the selected scatterer information to the terminal. The selected scatterer information may be transmitted to the terminal using any one of DCI, MAC-CE, or RRC signaling. Alternatively, the selected scatterer information may be transmitted via a SIB if a specific terminal-specific SIB can be configured. Transmitting the scatterer information to the terminal may be understood as transmitting the terminal beam index to be used by the terminal and / or the base station beam index information used in the scatterer sensing procedure to the terminal. Accordingly, the terminal can identify the terminal beam to be used based on the received scatterer information.

[0311] In step S1414, the base station can subdivide the base station beam(s) for the selected VR areas into a predetermined number. Since the base station beam used for scatterer sensing is formed by a relatively large number of antenna arrays, the beam width may also be a wide beam. Therefore, the base station can further subdivide the wide beam. For example, the beam corresponding to base station beam index #1 can be subdivided into n beams. Here, n can be a natural number greater than or equal to 1, and when n is 1, it can mean that subdivision is not applied. In the following description, for convenience of explanation, it is assumed that n is 3, that is, each base station beam is divided into three distinct beams.

[0312] As described above, if base station beam index #1 corresponding to VR #1 and base station beam index #3 corresponding to VR #2 are selected, the base station can split base station beam index #1 into three beams as candidate beams of VR #1.

[0313] In step S1416, the base station can instruct the terminal to perform an RSRP measurement report. Accordingly, the terminal can receive an RSRP measurement report instruction from the base station. The RSRP measurement report instruction may be indicated by upper layer signaling such as RRC signaling or MAC-CE, or may be transmitted as information such as DCI. The RSRP measurement report instruction may include information about the RSRP measurement time and report time. In addition, the RSRP measurement report instruction may include terminal beam information that the terminal should use. If the terminal can know the terminal beam information that the terminal should perform measurement on from the scatterer information transmitted in step S1412, the terminal beam information may not be included in the RSRP measurement report instruction.

[0314] In step S1418, the base station can select a combination of subdivided beams. For example, if the base station beam of base station beam index #1 corresponding to VR #1 is subdivided into three beams as described above, each of the subdivided base station beams can be distinguished as base station beam index #1-1, base station beam index #1-2, and base station beam index #1-3. In addition, if the base station beam of base station beam index #3 corresponding to VR #2 is subdivided into three beams as described above, each of the subdivided base station beams can be distinguished as base station beam index #3-1, base station beam index #3-2, and base station beam index #3-3.

[0315] In this way, since the base station beam corresponding to base station beam index #1 is divided into three subdivided beams, and the base station beam corresponding to base station beam index #3 is composed of three subdivided beams, there can be nine cases of combinations of subdivided beams.

[0316] At step S1418, the base station can select any one of the combinations of these nine base station segmentation beams.

[0317] In step S1420, the base station can transmit an RS to the terminal using the selected subdivided beam combination. For example, if the base station selects a subdivided beam combination of base station beam index #1-1 and base station beam index #3-1, the RS can be transmitted to the terminal through the beam corresponding to base station beam index #1-1 via VR #1 and the beam corresponding to base station beam index #3-1 via VR #2. As another example, if the base station selects a subdivided beam combination of base station beam index #1-1 and base station beam index #3-2, the RS can be transmitted to the terminal through the beam corresponding to base station beam index #1-1 via VR #1 and the beam corresponding to base station beam index #3-2 via VR #2.

[0318] Therefore, the terminal can receive the subdivided beams through VR #1 and the subdivided beams through VR #2. In addition, since each beam contains an RS, the terminal can receive the RS received from each beam and measure the RSRP. The terminal can report the measured RSRP to the base station at the RSRP reporting time based on the RSRP measurement report instruction received from the base station in step S1416.

[0319] In step S1422, the base station can receive an RSRP measurement report from the terminal, map it with the detailed beam pair information, and store it. Then, in step S1424, the base station can check whether RSRP measurements for all detailed beam combinations have been completed. If RSRP measurements for all detailed beam combinations have not been completed, the base station can proceed to step S1426. On the other hand, if RSRP measurements for all detailed beam combinations have been completed, the base station can proceed to step S1428.

[0320] In step S1426, the base station may select a subdivided beam combination for which RSRP measurement has not yet been completed. Step S1420 may then be performed again. If the RSRP measurement report instruction of step S1416 was previously transmitted via DCI, the base station may also retransmit the RSRP measurement report instruction to the terminal in step S1420 (not shown in FIG. 14b).

[0321] Through the above procedure, the pairs of each segmented beam and the RSRP measurement values ​​received from the terminal and the reception beams of the terminal can be exemplified in a table as shown in Table 11 below.

[0322] Candidate beam of VR #1 Candidate beam of VR #2 Terminal beam RSRP measurement value Base station beam index #1-1 Base station beam index #3-1 Terminal beam index #1, Terminal beam index #4 RSRP_79 Base station beam index #1-1 Base station beam index #3-2 Terminal beam index #1, Terminal beam index #4 RSRP_88 Base station beam index #1-1 Base station beam index #3-3 Terminal beam index #1, Terminal beam index #4 RSRP_97… … … … Base station beam index #1-3 Base station beam index #3-3 Terminal beam index #1, Terminal beam index #4 RSRP_64

[0323] According to Table 11, the pairs of candidate beams of VR #1 and VR #2 are switched, but the terminal beam index is the same as the beam index previously used for scatterer detection.

[0324] In step S1428, the base station may determine the subdivided beam combination with the highest RSRP value as the base station beam. According to the example in Table 11, when using the subdivided beam combination of base station beam index #1-1 and rhk base station beam index #3-3, it may be the case with the highest RSRP value. Therefore, the base station may determine the combination of base station beam index #1-1 and base station beam index #3-3 as the base station beam for communicating with the terminal.

[0325] Then, below, we will examine the entire operation of sections [1] to [3] described above with reference to the attached drawings.

[0326] Figure 15 is a conceptual diagram for explaining a beam management method considering VR in a communication system using an XL-MIMO antenna.

[0327] Step S1510 may be a scatterer sensing process. As previously explained, the scatterer sensing process may be a procedure for determining whether scatterers exist on the communication path between a base station and a terminal in a communication system using an XL-MIMO antenna. A more detailed description of this process is as follows.

[0328] In step S1511, either the base station or the terminal may be the subject and transmit a reference signal for scatterer sensing. For example, as described in FIG. 11a, the base station may be the subject and transmit a reference signal to the terminal. In the case of FIG. 11a, the terminal may be a receiving node that receives the reference signal transmitted by the base station. As another example, in the case of FIG. 11b, the terminal may be the subject and transmit a reference signal to the base station. In the case of FIG. 11b, the base station may be a receiving node that receives the reference signal transmitted by the terminal.

[0329] In step S1512, the base station and the terminal can select a base station beam and a terminal beam corresponding to the scatterer.

[0330] Steps S1511 and S1512 are the same as those described above in FIGS. 11a and 11b, so redundant descriptions will be omitted.

[0331] Step S1520 may be a hierarchical VR estimation process. As previously described, this may be a procedure for hierarchically estimating the VR area of ​​the XL-MIMO antenna corresponding to the sensed scatterers. Step S1520 may be structured as follows.

[0332] In step S1521, the base station can calculate (or determine) the number of steps in the hierarchical VR estimation process. The base station can perform the VR estimation process only if the terminal supports VR estimation. When calculating the number of steps in the VR estimation process, the base station may consider VR-related information received from the terminal, such as delay requirement information, and may also consider the number of antenna ports capable of transmitting and receiving simultaneously at the base station.

[0333] In step S1522, the base station can receive an RS signal from the terminal via the representative antenna. Therefore, at this time, the base station can instruct the terminal to transmit an RS signal in advance to receive the RS signal.

[0334] In step S1523, the base station can measure the RSRP of the RS received from the terminal. Then, the measured RSRP value can be compared with a threshold value to determine a set of antenna candidates. At this time, the antenna candidates can be determined in the same manner as described previously in FIGS. 13a and 13b.

[0335] In step S1524, the base station can estimate the VR for all scatterers. VR estimation can be performed in the same manner as the procedures described in FIGS. 12a and 12b and in FIGS. 13a and 13b.

[0336] In step S1520, the hierarchical VR estimation process is described from the base station perspective, but can also be performed from the terminal perspective as described above.

[0337] Step S1530 may be a base station beam and terminal beam selection process. The base station beam and terminal beam may have been determined in steps S1510 and S1520, respectively, for each scatterer. With the base station beam and terminal beam corresponding to each scatterer determined, the final base station beam and terminal beam may be selected as follows.

[0338] In step S1531, the base station can compare the performance of scatterer-VR combinations. The performance comparison operation may include a step in which the terminal transmits an RS to the base station, a step in which the base station receives the RS and measures the RSRP, and a step in which the base station selects a scatterer-VR combination with the highest RSRP value among the RSRPs measured, or a predetermined number of scatterer-VR combinations in descending order of RSRP values.

[0339] In step S1532, the base station transmits RS to the terminal through the candidate beams segmented by the selected VR, and selects the final base station beam based on the RSRP value received from the terminal. The operation of step S1530 described above may correspond to the operations of FIGS. 14a and 14b described above.

[0340] The operations of the method according to the present disclosure can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores information readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0341] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0342] While some aspects of the present disclosure have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most significant method steps may be performed by such a device.

[0343] A programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described in the present disclosure. The field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described in the present disclosure. In general, the methods are preferably performed by some hardware device.

[0344] Although the present disclosure has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the claims below.

Claims

1. In the terminal method, A step of beam sweeping terminal beams and transmitting a first signal including a terminal beam index and a first reference signal (RS) for each beam to a base station; A step of receiving information on scatterers existing on a communication path between the terminal and the base station from the base station; A step of receiving information on the number of estimation steps for antenna estimation from the above base station; A step of performing a first procedure for hierarchically estimating visibility regions (VRs) among antennas of the base station for each scatterer included in the base station and the scatterer information as much as the estimation step number information; and A step of performing a second procedure for determining a base station beam to be used in the above base station and each VR, The above scatter information includes a scatter identifier and a terminal beam index corresponding to the scatterer. Terminal method.

2. In claim 1, Further comprising a step of transmitting service information and VR-related information to be provided from the terminal to the base station after receiving the scattering information. Terminal method.

3. In claim 2, The VR-related information includes at least one of information on whether the VR supports hierarchical estimation or information on the number of beams that the terminal can form simultaneously. Terminal method.

4. In claim 1, The above first procedure is, A step of receiving an RS transmission instruction through a terminal beam corresponding to at least one of the scatterers included in the scatterer information from the base station; and Further comprising a step of transmitting RS based on the above RS transmission instruction, Terminal method.

5. In claim 4, The above RS transmission instructions are: Including at least one of a period for transmitting the RS, a time point for transmitting the RS, or a number of times for transmitting the RS. Terminal method.

6. In claim 1, The second procedure above is, A step of receiving an RS transmission instruction through a terminal beam corresponding to at least one of the scatterers included in the scatterer information from the base station; and A step of transmitting a second signal including a second RS based on the RS transmission instruction; A step of receiving a reference signals received power (RSRP) measurement report instruction message including terminal beam information from the base station; A step of measuring RSRP of RS received from the base station through the terminal beam indicated in the terminal beam information; and Further comprising a step of reporting the measured RSRP to the base station, Terminal method.

7. In claim 1, The above base station has an extra-large scale multiple input multiple output (XL-MIMO) antenna, The scatterer comprises at least one of a building, a vehicle, a person, a sculpture, an intelligent reflecting surface (IRS), a reconfigurable intelligent surface (RIS), or airborne particles. Terminal method.

8. In the method of the base station, A step of receiving a first signal including a reference signal from a terminal by beam sweeping the entire antenna array of an extra-large scale multiple input multiple output (XL-MIMO) antenna; A step of obtaining scatterer information by measuring the first reference signals received power (RSRP) of the first signal; A step of transmitting the acquired scattering information to the terminal; A step of determining the number of steps for the above XL-MIMO antenna estimation; A step of transmitting the determined step number information to the terminal; A step of performing a first procedure for hierarchically estimating visibility regions (VRs) among the XL-MIMO antennas for each scatterer included in the scatterer information as much as the estimation step number information; and Comprising a step of performing a second procedure for determining a base station beam to be used in the terminal and one or more VR areas, The above scatter information includes a scatter identifier and a terminal beam index corresponding to the scatterer. Method of base station.

9. In claim 8, Further comprising a step of receiving service information and VR related information of the terminal from the terminal after transmitting the scattering information. Method of base station.

10. In claim 9, The VR-related information includes at least one of information on whether the VR supports step-by-step estimation or information on the number of beams that the terminal can form simultaneously. Method of base station.

11. In claim 8, The above first procedure is, a step of determining the number of estimation steps of the above VRs; and Further comprising the step of performing a third procedure for determining VR in the entire array of XL-MIMO antennas as many times as the number of estimation steps, The estimated number of steps of the above VRs is determined based on at least one of the delay requirement received from the terminal or the number of antenna ports that the base station can simultaneously transmit and receive. Method of base station.

12. In claim 11, The third procedure above is for each of the above scatterers: A step of dividing the entire XL-MIMO antenna array into a predetermined number of first antenna regions; A step of selecting first representative antennas for each of the divided first antenna regions; A step of measuring a second RSRP of RS received from the terminal through the first representative antennas; A step of determining the first antenna area(s) including the first representative antennas having the second RSRP exceeding a preset first threshold as a VR candidate area; A step of dividing each of the above VR candidate areas into a predetermined number of second antenna areas; A step of selecting second representative antennas for each of the divided second antenna regions; A step of measuring a third RSRP of RS received from the terminal through the second representative antennas; and The third RSRP further comprises a step of determining a second antenna area(s) including a second representative antenna exceeding a preset second threshold as a VR area. Method of base station.

13. In claim 8, The second procedure above, for each scatterer: A step of transmitting an RS transmission instruction message through a terminal beam corresponding to the above scatterer; and A step of measuring the fourth RSRP of RS received from the terminal through antennas in the VR area; A step of determining a combination between the measured scatterer and the VR region based on the measured fourth RSRP; Further comprising a step of performing a fourth procedure for determining a segmented beam to be communicated with the terminal based on a combination between the scatterer and the VR region. Method of base station.

14. In claim 13, The above fourth procedure is: A step of transmitting combination information between the determined scatterer and the VR area to the terminal; A step of dividing each of the base station beams to be transmitted through the above VR areas into a predetermined number; A step of transmitting an RSRP measurement report instruction message including the terminal beam information to the terminal; A step of determining combinations of pairs of segmented beams of the different VR areas; A step of transmitting RS to the terminal through beams based on combinations of pairs of the above-described segmented beams; A step of receiving an RSRP report message corresponding to beams based on combinations of the above-described subdivided beams from the terminal; and Further comprising a step of determining a base station beam among the segmented beams based on the received RSRP report message. Method of base station.

15. At the terminal, Comprising at least one processor, said at least one processor comprising: Transmitting a first signal including a terminal beam index and a first reference signal (RS) to a base station by beam sweeping the terminal beams for each beam; Receive information on scatterers existing on the communication path between the terminal and the base station from the base station; Receive information on the number of estimation steps for antenna estimation from the above base station; A first procedure is performed for hierarchically estimating visibility regions (VRs) among antennas of the base station for each scatterer included in the base station and the scatterer information as much as the estimation step number information; and Causes the second procedure to be performed for determining the base station beam to be used at the above base station and each VR, The above scatter information includes a scatter identifier and a terminal beam index corresponding to the scatterer. Terminal.

16. In claim 15, At least one processor of the above: After receiving the above scattering information, it further causes the service information and VR related information to be provided from the terminal to be transmitted to the base station. Terminal.

17. In claim 16, The VR-related information includes at least one of information on whether the VR supports hierarchical estimation or information on the number of beams that the terminal can form simultaneously. Terminal.

18. In claim 15, At least one processor, in said first procedure: Receiving an RS transmission instruction from the base station through a terminal beam corresponding to at least one scatterer among the scatterers included in the scatterer information; and Further causing RS to be transmitted based on the above RS transmission instruction, Terminal.

19. In claim 18, The above RS transmission instructions are: Including at least one of a period for transmitting the RS, a time point for transmitting the RS, or a number of times for transmitting the RS. Terminal.

20. In claim 15, At least one processor in the second procedure, Receiving an RS transmission instruction from the base station through a terminal beam corresponding to at least one scatterer among the scatterers included in the scatterer information; and Transmitting a second signal including a second RS based on the above RS transmission instruction; Receive a reference signals received power (RSRP) measurement report instruction message including terminal beam information from the base station; Measure the RSRP of the RS received from the base station through the terminal beam indicated in the terminal beam information; and further causing the measured RSRP to be reported to the base station; Terminal.

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