Method and apparatus for acquiring beam book for RIS control in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data rate than a 4G communication system such as LTE. According to an embodiment of the present disclosure, a method for generating a beam book for controlling a beam when a beam transmitted from a base station is reflected by an RIS and transmitted to a UE in a wireless communication system is provided. The method may include receiving information about an RIS ID from an RIS control unit (RCU), the RCU being a communication entity controlling an RIS that reflects a beam transmitted from a BS and transmits the reflected beam to a user equipment (UE); identifying an angle of incidence from the BS to the RIS corresponding to the RIS ID based on the information on the RIS ID; and determining information on a beam for scanning the preset area based on the identified incident angle, in which a beam for RIS control in the RCU is obtained based on the identified incident angle and the determined information on the beam.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for generating a beam book for controlling a beam transmitted from a Base Station (BS). Background Art

[0002] Considering the development of wireless communication from generation to generation, technology mainly used for services targeting humans, such as voice calls, multimedia services and data services, has been developed. The connection devices that have exploded after the commercialization of the fifth generation (5G) communication system are expected to be connected to the communication network. Examples of things connected to the network can include vehicles, robots, drones, household appliances, displays, smart sensors installed in various infrastructures, construction machinery and factory equipment. Mobile devices are expected to evolve in various form factors, such as augmented reality glasses, virtual reality headsets and holographic devices. In the sixth generation (6G) era, efforts are being made to develop improved 6G communication systems so as to provide various services by connecting millions of devices and things. For this reason, 6G communication systems are called super 5G systems.

[0003] In the 6G communication system expected to be realized around 2030, the peak data rate is 1 tera (i.e., 1,000 gigabits) bps, and the wireless delay time is 100 microseconds (μsec). That is, the data rate in the 6G communication system is 50 times higher than that in the 5G communication system, and the wireless delay time is reduced to 1 / 10.

[0004] In order to achieve such high data rates and ultra-low latency, it is considered to implement 6G communication systems in the terahertz band (e.g., 95 gigahertz (GHz) to 3 terahertz (THz) band). It is expected that since the path loss and atmospheric absorption in the terahertz band are more serious than those in the mmWave (millimeter wave) band introduced in 5G, the technology that can ensure the signal transmission distance (i.e., coverage) will become more critical. As the main technology for ensuring coverage, it is necessary to develop radio frequency (RF) elements, antennas, and novel waveforms with better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, and multi-antenna transmission technologies (such as massive antennas). In addition, discussions have been ongoing on new technologies for improving the coverage of terahertz band signals, such as lenses and antennas based on metamaterials, high-dimensional spatial multiplexing using orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS).

[0005] In addition, in order to improve frequency efficiency and system network performance, the following technologies have been developed for 6G communication systems: full-duplex technology for enabling uplink transmission and downlink transmission to use the same frequency resources at the same time; network technology for utilizing satellites, high altitude platform stations (HAPS), etc. in an integrated manner; improved network structure for supporting mobile base stations, etc. and realizing network operation optimization and automation, etc.; dynamic spectrum sharing technology for avoiding collisions based on spectrum usage prediction; artificial intelligence (AI)-based communication technology for system optimization by utilizing AI from the design stage and internalizing end-to-end AI support functions; and next-generation distributed computing technology for providing services with complexity beyond the computing power limit of user equipment (UE) through ultra-high performance communication and computing resources (such as mobile edge computing (MEC), cloud, etc.). In addition, attempts continue to be made to strengthen connectivity between devices, optimize networks, promote the softening of network entities, and increase the openness of wireless communications by designing new protocols to be used in 6G communication systems, developing mechanisms for realizing hardware-based security environments and secure use of data, and developing technologies for maintaining privacy.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity (including human-to-machine and machine-to-machine) will allow the next hyper-connected experience. In particular, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital copies can be provided through 6G communication systems. In addition, services such as remote surgery, industrial automation, and emergency response for enhanced safety and reliability will be provided through 6G communication systems and applied to various fields such as industry, healthcare, automobiles, and home appliances. Summary of the invention

[0007] Technical issues

[0008] The disclosed embodiments may provide a method and apparatus for generating a beambook for controlling a beam when a beam transmitted from a base station (BS) is reflected by a reconfigurable smart surface (RIS) and transmitted to a user equipment (UE) in a wireless communication system.

[0009] Technical Solution

[0010] In an embodiment of the present disclosure, a method by which a base station (BS) performs communication in a wireless communication system may include receiving information about a RIS identification (ID) from a reconfigurable smart surface (RIS) control unit (RCU), the RIS control unit (RCU) being a communication entity that controls a RIS that reflects a beam transmitted from the BS and transmits the reflected beam to a user equipment (UE). The method may include: based on the information about the RIS ID, identifying an incident angle from the BS to the RIS corresponding to the RIS ID. The method may include determining beam-related information for scanning a preset area based on the identified incident angle, wherein the beam for RIS control in the RCU is obtained based on the identified incident angle and the determined beam-related information.

[0011] In an embodiment of the present disclosure, a base station (BS) for performing communication in a wireless communication system, the BS may include a transceiver and at least one processor connected to the transceiver. In an embodiment of the present disclosure, the at least one processor may be configured to: receive information about a RIS identification (ID) from a reconfigurable smart surface (RIS) control unit (RCU), the RIS control unit (RCU) being a communication entity of the RIS that controls the reflection of a beam sent from the BS and sends the reflected beam to a user equipment (UE); based on the information about the RIS ID, identify an incident angle from the BS to the RIS corresponding to the RIS ID; and based on the identified incident angle, determine beam-related information for scanning a preset area, wherein the beam for RIS control in the RCU is obtained based on the identified incident angle and the determined beam-related information.

[0012] In an embodiment of the present disclosure, there may be provided a computer-readable recording medium having recorded thereon a program for executing the method on a computer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram for describing a method of performing beam transmission using a reconfigurable smart surface (RIS) according to an embodiment.

[0014] Figure 2 is a flowchart for describing a method for generating a beamline according to an embodiment.

[0015] Figure 3 is a flowchart for describing a method by which a RIS control unit (RCU) generates a beam book according to an embodiment.

[0016] Figure 4 is a flowchart for describing a method by which a base station (BS) generates a beamform according to an embodiment.

[0017] Figure 5is a flowchart for describing a method by which an RCU generates a beam when an incident angle is variable according to an embodiment.

[0018] Figure 6 is a flowchart for describing a method by which a BS generates a beamform when an incident angle is variable according to an embodiment.

[0019] Figure 7 FIG. 1 is a flowchart for describing an embodiment of generating a beamform by reflecting a scanning range according to an embodiment.

[0020] Figure 8 is a diagram for describing a beam transmission path using RIS according to an embodiment.

[0021] Fig.9A and Fig. 9B is a diagram for describing a system for supporting a plurality of areas by using a beamform according to an embodiment.

[0022] Fig. 10A and Fig. 10B is a diagram for describing a system using a plurality of RISs according to an embodiment.

[0023] Fig.11A and Fig. 11B is a diagram for describing a system using a plurality of BSs according to an embodiment.

[0024] Fig.12 is a diagram for describing an example of a predetermined beam book according to an embodiment.

[0025] Fig.13 is a diagram for describing a scanning range according to an embodiment.

[0026] Fig.14 is a diagram for describing a method of estimating an incident angle according to an embodiment.

[0027] Fig.15 is a block diagram schematically illustrating a configuration of a BS according to an embodiment.

[0028] Fig.16 is a block diagram schematically illustrating a configuration of an RCU according to an embodiment. DETAILED DESCRIPTION

[0029] Embodiments of the present disclosure will now be described more fully with reference to the accompanying drawings.

[0030] Since the present disclosure allows various changes and many examples, the specific embodiments of the present disclosure will be shown in the drawings and described in detail in the written description. However, this is not intended to limit the present disclosure to a specific mode of practice, and it will be understood that all changes, equivalents and substitutes that do not depart from the spirit and technical scope of the various embodiments are included in the present disclosure.

[0031] In the description of the embodiments, when it is considered that some detailed explanations of the related art may unnecessarily obscure the essence of the present disclosure, some detailed explanations of the related art are omitted. In addition, the numbers (e.g., first and second) used in the description of the specification are merely identifier codes for distinguishing one element from another element.

[0032] The terms used herein are those common terms currently widely used in the art in view of the functions in the present disclosure, but the terms may vary according to the intention of a person of ordinary skill in the art, precedents, or new technologies in the art. In addition, some of the terms used herein may be arbitrarily selected by the applicant, and in this case, these terms are defined in detail below. Therefore, the specific terms used herein should be defined based on their unique meanings and the entire context of the present disclosure.

[0033] The scope of the present disclosure may be defined by the claims described below rather than by the detailed description. Various features included only in one claim category of the present disclosure (e.g., method claims) may be claimed in other claim categories (e.g., system claims). In addition, the embodiments of the present disclosure may include not only the combination of features specified in the attached claims, but also various combinations of the individual features within the claims. The scope of the present disclosure is defined by the following claims, and the present disclosure is intended to cover modifications or variations of the present disclosure as long as they fall within the scope of the attached claims and their equivalents.

[0034] Furthermore, in the present disclosure, it will be understood that, unless otherwise stated, when elements are "connected" or "coupled" to each other, the elements may be directly connected or coupled to each other, but may alternatively be connected or coupled to each other through an intermediate element therebetween. Furthermore, an element being referred to as being "connected" to another element will be understood to include the element being "directly connected" or "physically connected" to another element, or "electrically connected" to another element with another element therebetween. The terms "send," "receive," and "communicate" encompass both direct and indirect communications.

[0035] When a component “includes” an element in the present disclosure, unless otherwise described, another element may be further included rather than excluding the presence of another element.

[0036] In addition, in the present disclosure, with respect to an element represented as a "unit" or "module", two or more elements may be combined into one element, or one element may be divided into two or more elements according to subdivided functions. These functions may be implemented as hardware, software, or a combination of hardware and software. In addition, each element described below may additionally perform some or all of the functions performed by another element in addition to its own main function, and some of the main functions of each element may be fully performed by another element.

[0037] The singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Terms (including technical or scientific terms) used herein may have the same meaning as commonly understood by one of ordinary skill in the art described in this disclosure.

[0038] Throughout this disclosure, unless otherwise described, "or" is inclusive rather than exclusive. Thus, unless otherwise expressly indicated or the context indicates otherwise, the statement "A or B" may include A, may include B, or may include both A and B. In this disclosure, the phrase "at least one of" or "one or more" when used with a list of items means that different combinations of one or more of the listed items may be used, or only one item in the list may be required. For example, "at least one of A, B, and C" may include any of the following combinations: A, B, C, A and B, A and C, B and C, or A and B and C.

[0039] It will be understood that each box of the flowchart illustration and the combination of boxes in the flowchart illustration can be implemented by computer program instructions. Because these computer program instructions can be loaded into a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, the instructions executed by the processor of the computer or other programmable data processing device generate components for performing the functions specified in the flowchart box (or multiple). Because these computer program instructions can also be stored in a computer executable or computer readable memory that can instruct a computer or other programmable data processing device to function in a specific manner, the instructions stored in the computer executable or computer readable memory can produce an article including instruction components for performing the functions stored in the flowchart box (or multiple). Because the computer program instructions can also be loaded into a computer or other programmable data processing device, a series of operating steps can be performed on a computer or other programmable data processing device to produce a computer-implemented process, and therefore, the instructions executed on the computer or other programmable data processing device can provide steps for implementing the functions specified in the flowchart box (or multiple).

[0040] In addition, each frame can represent a module, a fragment or a part of a code, which includes one or more executable instructions for realizing a specified logical function (or multiple). It should also be noted that in some alternative implementations, the functions mentioned in the frame may not occur in order. For example, two frames shown in succession can actually be performed substantially simultaneously, or frames can sometimes be performed in reverse order, depending on the functions involved.

[0041] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure can be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the accompanying drawings, in order to clearly describe the present disclosure, parts not related to the description are omitted, and the same reference numerals represent the same elements throughout the specification.

[0042] In addition, in the following, long term evolution (LTE), advanced LTE (LTE-A) or 5th generation (5G) systems may be described as examples, but embodiments of the present disclosure may also be applied to other communication systems with similar technical backgrounds or channel types. For example, other communication systems may include advanced 5G or 6th generation mobile communication technology (6G) developed after 5G mobile communication technology (or new radio (NR)), and the 5G described below may be a concept including traditional LTE and LTE-A and other services similar thereto. In addition, according to the judgment of ordinary technicians in this field, the present disclosure may be applied to other communication systems with some modifications without departing from the scope of the present disclosure.

[0043] Terms used herein will be briefly described, and embodiments of the present disclosure will be described in detail.

[0044] The terms used herein are terms defined in consideration of functions in the present disclosure, but the terms may vary depending on the intention of a user or operator, precedents, etc. Therefore, the terms used herein should be defined based on the meanings of the terms and descriptions throughout the specification.

[0045] In the present disclosure, a base station (BS) is a subject configured to perform resource allocation for a user equipment (UE), and may be, but is not limited to, at least one of a gNodeB, an eNodeB, a Node B (or an xNode B (x is a character including "g" and "e")), a base station (BS), a wireless access unit, a BS controller, a satellite, an air vehicle, or a node on a network. The BS in the present disclosure may indicate the BS itself, a cell, or a radio unit (RU) according to interpretation, and a target for exchanging messages with the UE may be a distributed unit (DU) or a centralized unit (CU), depending on its structure.

[0046] Furthermore, in the present disclosure, a user equipment (UE) may include a mobile station (MS), a cellular phone, a smart phone, a computer, a vehicle, a satellite, or a multimedia system capable of performing a communication function.

[0047] In the following, for the convenience of explanation, terms indicating broadcast information, terms indicating control information, terms related to communication coverage, terms indicating a change in state (e.g., an event), terms indicating a network entity, terms indicating a message, and terms indicating a component of a device are exemplified. Therefore, the present disclosure is not limited to the terms described below, and other terms indicating objects having equivalent technical meanings may be used.

[0048] For ease of explanation below, terms and names defined in the LTE and NR standards are used, wherein the LTE and NR standards are the latest standards defined by the Third Generation Partnership Project (3GPP) organization among the currently existing communication standards. However, the present disclosure is not limited to the terms and names, and can also be applied to systems that comply with other standards.

[0049] With the development of mobile communication technology, new methods are being proposed for efficiently transmitting beams transmitted from a base station (BS) to a user equipment (UE). When considering the implementation of 6G in the terahertz band, coverage problems may occur due to path loss and atmospheric absorption that are more severe than those in the mmWave band of 5G. Therefore, a reconfigurable smart surface (RIS), which is one of the proposed technologies, can extend the range of an area that a single BS can cover by reflecting a beam in a shadow area and transmitting data to the UE. In addition, RIS can prevent data loss caused by beam blocking due to obstacles such as buildings that exist between the UE and the BS.

[0050] A beambook for existing analog beamforming can be set by considering only the angle of departure (AoD) because there is only a single path from the BS to the UE. For example, the BS can set a beambook including 56 beams by adjusting the AoD at 6° intervals, and the UE can set a beambook including 14 beams by adjusting the AoD using 7 azimuth angles and 2 zenith angles. However, during beam transmission using RIS, there are two paths from the BS to the UE. Therefore, a new beambook needs to be introduced for RIS control.

[0051] Figure 1 is a diagram for describing a method of performing beam transmission using RIS according to an embodiment.

[0052] refer to Figure 1, a wireless communication system for performing a beam transmission method using a RIS according to an embodiment may include, but is not limited to, a BS 10, a RIS control unit (RCU) 20, at least one UE 30 (e.g., 30a and 30b), and a RIS 40. Although the apparatus for controlling the RIS by signal transmission / reception to / from the BS is the RCU in the present disclosure, this is merely an example for convenience of explanation, and the apparatus for controlling the RIS according to the present disclosure is not limited to the RCU.

[0053] The RCU 20 is a unit for controlling the RIS 40, and can transmit and receive a signal 110 for controlling the RIS 40 to and from the BS 10, and can transmit a signal 120 for RIS control to the RIS 40. The RCU 20 can control one RCU 40 or can control a plurality of RCUs. The RCU 20 can perform wireless communication with one BS 10 or can perform wireless communication with a plurality of BSs.

[0054] The RIS 40 controlled by the RCU 20 may reflect the beam transmitted from the BS 10 and may transmit the reflected beam to the UE 30 located in the shadow area. In the present disclosure, the angle formed by the beam transmitted from the BS 10 and the RIS 40 is referred to as an incident angle (θ r ) 130. In addition, the angle formed by the beam transmitted from the BS 10 and reflected by the RIS 40 and the UE 30 is referred to as a reflection angle (θ t ) 140. The incident angle 130 may be recognized by the BS 10 or the RCU 20, or may be estimated by the RCU 20.

[0055] In order to transmit a beam from the BS 10 to the UE 30, the BS 10 and the RCU 20 may obtain a beam book for controlling the RIS 40. The RIS 40 may include a plurality of elements, and the beam book may include beam information corresponding to each element. The beam book may be generated based on the incident angle 130 and beam related information determined by the BS 10 according to the system operation purpose. In the present disclosure, the beam related information may include a scanning range and beam operation information.

[0056] The scanning range refers to the area that the BS 10 is to search in the shadow area 160 according to the system operation purpose. In the embodiment of the present disclosure, the scanning range can be indicated by the angle information of the reflection angle 140. For example, the scanning range can be indicated by using the minimum value of the reflection angle (θ t，min )140a and the maximum value of the reflection angle (θ t，max )140b to indicate (for example, θ t，min to θ t，max), or may be indicated by a specific value (e.g., -10° to 10°). The reflection angle 140 may be determined according to the capability of the RIS 40. The capability of the RIS 40 may include, but is not limited to, the hardware characteristics of the RIS 40 and the number of phase shift bits. In an embodiment of the present disclosure, the scanning range may be indicated in the form of a flag signal.

[0057] The beam operation information may be determined according to the operation purpose of the BS 10. In the present disclosure, the beam operation information may include but is not limited to the number of beams, bandwidth, and beam spacing. The beam operation information may be determined by considering the scanning range and the incident angle 130.

[0058] In an embodiment of the present disclosure, the BS 10 may generate a beam book based on the identified incident angle 130 and the determined beam-related information. The BS 10 may generate a beam book by reflecting the information about the hardware characteristics of the RIS 40 received from the RCU 20. In an embodiment of the present disclosure, the BS 10 may send the identified incident angle 130 and the determined beam-related information to the RCU 20, and the RCU 20 may generate a beam book based on the received information. The RCU 20 may generate a beam book by reflecting the information about the hardware characteristics of the RIS 40.

[0059] In an embodiment of the present disclosure, the incident angle 130 may be variable. When the incident angle 130 is variable, this may include a case where the BS 10 has mobility or the RIS 40 has mobility or rotation. In addition, when the incident angle 130 is variable, this may include a case where the angle of the BS 10 or the RIS 40 changes due to weather influences. When the incident angle 130 between the BS 10 and the RIS 40 changes, the BS 10 or the RCU 20 may estimate the incident angle 130. For example, the BS 10 or the RCU 20 may estimate the incident angle 130 by using a channel estimated by a channel state information reference signal (CSI-RS) or by using a beam scanning or an angle of arrival (AOA) estimation algorithm. When the incident angle 130 is estimated, it is assumed that the boresight values ​​of the RIS 40 and the RCU 20 are the same.

[0060] The UE 30 may receive a beam transmitted from the BS 10 by using the RIS 40. In an embodiment of the present disclosure, the UE 30 may measure a reference signal received power (RSRP) of a received signal to obtain an RSRP measurement value, and may send the RSRP measurement value to the BS 10. The BS 10 may set a specific area to be scanned based on the RSRP measurement value. In an embodiment of the present disclosure, a wireless communication system for performing a beam transmission method using the RIS may include a plurality of UEs 30. The plurality of UEs 30 may share one RIS 40.

[0061] In an embodiment of the present disclosure, in a wireless communication system using RIS to perform a beam transmission method, BS10 may perform scanning on multiple areas. BS10 may set beam related information differently for each of the multiple areas according to an operation purpose. In an embodiment of the present disclosure, BS10 may perform scanning on the entire scanning area according to the capability of RIS 40, and may perform scanning on a specific area where UE 30 exists.

[0062] In an embodiment of the present disclosure, a wireless communication system that uses RIS to perform a beam transmission method may include multiple RIS. When there are multiple RIS, the incident angle 130 formed with the BS10 may be different for each RIS, and the BS10 may set the number of beams and the beam width differently for each RIS according to the operation purpose. The BS10 may select the RIS 40 to be used from among the multiple RIS, and the RCU 20 may identify the ID of the RIS 20 to be used, and may send the ID of the RIS 20 to the BS 10. In order to perform beam scanning by using another RIS different from the currently used RIS, the BS10 and the RCU 20 may perform switching to the beam book obtained for the other RIS. Multiple RIS may be controlled by one RCU 20, or may each be controlled by a separate RCU 20.

[0063] In an embodiment of the present disclosure, a wireless communication system for performing a beam transmission method using a RIS may include a plurality of BSs. The plurality of BSs may operate the system by sharing one RIS 40. Since the location of each BS is different, the incident angle 130 may be recognized differently, and the range to be scanned by each BS and the beam operation information may be set differently.

[0064] The process of obtaining a beam book for RIS operation between the BS 10 and the RCU 20 will be described in detail in the following flowchart.

[0065] Figure 2 is a flowchart for describing a method for generating a beamline according to an embodiment.

[0066] In operation S210, the BS 10 may receive information about the RIS ID from the RCU 20. Hereinafter, for convenience of explanation, the information about the RIS ID is referred to as the RIS ID. The RIS ID is an identifier indicating the RIS to be used by the RCU 20. The RCU 20 may determine the RIS to be used according to the beam purpose and may identify the RIS ID corresponding to the RIS.

[0067] In operation S220, the BS 10 may identify an incident angle.

[0068] The incident angle is an angle formed by a beam transmitted from the BS 10 and the RIS, and refers to an angle of departure (AoD). In an embodiment of the present disclosure, when the location of the BS 10 and the RIS to be used are determined, the incident angle may correspond to the RIS ID. For example, when the BS 10 and the RIS are fixed, the BS 10 receiving information about the RIS ID may identify the incident angle mapped to the RIS in a one-to-one manner. In an embodiment of the present disclosure, when the RCU 20 is an entity registered in the wireless communication system, the BS 10 may receive information about the RIS ID and information about the incident angle through system information provided in the initial access process. In this case, operations S210 and S220 may be omitted.

[0069] In operation S230, the BS10 may determine beam related information. The beam related information may include information about a scanning range through beam reflection by the RIS. Hereinafter, for ease of explanation, the scanning range through beam reflection by the RIS is referred to as the scanning range of the beam. In addition, the beam related information may include beam operation information. The beam related information may be determined based on the incident angle identified by the BS10. For example, when the incident angle is 30°, the scanning range may be determined to be a maximum of -60° to 60°. The number of beams to be used, the beam width, and the beam spacing may be determined according to the scanning range.

[0070] In an embodiment of the present disclosure, the scanning range of the beam may include the entire scanning area or a specific area in the entire area according to the capability of the RIS. Hereinafter, for the convenience of explanation, the entire scanning area is referred to as the global scanning range, and the specific area in the entire area is referred to as the local scanning area. The global scanning range may be determined according to the capability of the RIS. The capability of the RIS may include, but is not limited to, the hardware characteristics of the RIS and the number of phase shift bits. In an embodiment of the present disclosure, it is possible to check whether there is a UE in the shadow area by using the global scanning range. When the surrounding area of ​​the UE determined to be located in the shadow area needs to be scanned, the local scanning range may be used. In an embodiment of the present disclosure, the local scanning range may be determined by a beam scanning result based on a beam book generated according to the global scanning range. For example, according to the global scanning, an area corresponding to a preset angle range (e.g., -20° to 20°) based on a beam with the highest reference signal received power (RSRP) or a beam with an RSRP higher than a preset reference value may be set as a local scanning range. In an embodiment of the present disclosure, the BS10 and the RCU 20 may obtain a first beam book according to the global scanning range and obtain a second beam book according to the local scanning range, which will be referred to below. Figure 7 Detailed description.

[0071] In an embodiment of the present disclosure, the scanning range of the beam may be indicated by the angle information of the reflection angle or a flag signal. The angle of arrival (AoA) as the angle of the beam reflected by the RIS is referred to as the reflection angle (θ t ) 140. The scanning range of the beam can be indicated by the angle information based on the reflection angle (θ t ), such as the minimum reflection angle (θ t，min ) to the maximum reflection angle (θ t，max ) (e.g., -60° to 60°). When the RCU 20 knows a plurality of scanning ranges in advance, the scanning range of the beam can be determined in the form of a flag signal indicating the scanning range. For example, when "global scanning range = 1" is set, "1" can be used to indicate scanning of the entire area.

[0072] In an embodiment of the present disclosure, the beam operation information may include at least one of the number of beams to be operated, the beam width, or the beam spacing. The number of beams to be operated may refer to the number of beams set by the BS in consideration of the synchronization signal broadcast block (SSB) resource. In an embodiment of the present disclosure, the number of beams to be operated may be indicated in the form of an integer. The beam width refers to the width of the beam reflected by the RIS. In an embodiment of the present disclosure, when the beam width is predefined, the BS10 may indicate the beam width by an index. The BS10 may indicate the beam width according to the beam purpose. For example, the BS10 may narrow the beam width according to the beam purpose in order to increase the SINR. The beam spacing may be set according to the scanning range of the beam and the number of beams. In an embodiment of the present disclosure, the beam spacing may be set to be uniform by the BS10, or the beam spacing may be set to be uneven.

[0073] In an embodiment of the present disclosure, information about the identified incident angle and the determined beam-related information may be transmitted to the RCU 20. In an embodiment of the present disclosure, information about the identified incident angle may be transmitted together with the determined beam-related information, or may be transmitted separately.

[0074] In operation S240, the BS 10 or the RCU 20 may obtain a beam book based on the identified incident angle and the determined beam-related information. The beam book may include information about a beam reflected to the UE by considering two paths by the RIS and reflecting beam-related information such as a scanning range and the number of beams.

[0075] In an embodiment of the present disclosure, the beam may be generated by the RCU 20, which receives information about the identified incident angle and the determined beam-related information. In an embodiment of the present disclosure, the beam may be generated by the BS 10 based on the identified incident angle and the determined beam-related information. The beam generated by the BS 10 may be sent to the RCU 20, which will be referred to below. Figure 3 and Figure 4 Detailed description.

[0076] In operation S250, the BS 10 and the RCU 20 may control the RIS based on the acquired beam book. The BS 10 and the RCU 20 may transmit and receive a signal for controlling the RIS, and the RCU 20 may transmit a signal for controlling the RIS to the RIS based on the acquired beam book.

[0077] Figure 3 1 is a flowchart for describing a method by which an RCU generates a beam according to an embodiment. Figure 2 The operations are the same as those in the detailed description.

[0078] refer to Figure 3 The RCU 20 that receives the identified incident angle and the determined beam-related information may generate a beam book.

[0079] In operation S310, the BS 10 may receive information about a RIS ID from the RCU 20. The RIS ID is an identifier indicating a RIS to be used by the RCU 20. The RCU 20 may determine a RIS to be used according to a beam purpose, and may identify a RIS ID corresponding to the RIS.

[0080] In operation S320, the BS 10 may identify an incident angle.

[0081] The incident angle is an angle formed by a beam transmitted from the BS 10 and the RIS, and indicates an angle of departure (AoD). In an embodiment of the present disclosure, the incident angle may correspond to the RIS ID. For example, when the BS 10 and the RIS are fixed, the BS 10 receiving information about the RIS ID may identify the incident angle corresponding to the RIS in a one-to-one manner. In an embodiment of the present disclosure, when the RCU 20 itself is an entity registered in the wireless communication system, the BS 10 may receive information about the RIS and the RCU 20.

[0082] In operation S330, the BS 10 may determine beam-related information. The beam-related information may include information about a scanning range reflected by a beam of the RIS. In addition, the beam-related information may include beam operation information. The beam-related information may be determined based on the identified incident angle.

[0083] In operation S340, the BS 10 may transmit the information about the incident angle and the beam-related information to the RCU 20. In detail, the BS 10 may transmit the information about the incident angle identified in operation S320 and the beam-related information determined in operation S330.

[0084] In an embodiment of the present disclosure, information about the identified incident angle and the determined beam-related information may be sent together from the BS 10 to the RCU 20. In an embodiment of the present disclosure, information about the identified incident angle and the determined beam-related information may be sent separately from the BS 10 to the RCU 20. In an embodiment of the present disclosure, information about the identified incident angle may be sent from the BS 10 to the RCU 20 before the beam-related information is determined.

[0085] In operation S350, the RCU 20 may generate a beam book. The beam book may be generated based on the identified incident angle received from the BS 10 and the determined beam-related information.

[0086] The beam generated by the RCU 20 may reflect the hardware characteristics of the RIS. For example, the hardware characteristics of the RIS may include at least one of the size of the RIS, the RIS unit cell pattern, the RIS unit cell phase error, the specular reflection loss, or the unit cell reflection loss.

[0087] In an embodiment of the present disclosure, when there are multiple scanning ranges to be searched by the BS 10, multiple beam books for the multiple scanning ranges may be generated. For example, when a first beam book for a first area and a second beam book for a second area are generated, the first beam book may include information about 6 beams based on a global scanning range (e.g., -60° to 60°), and the second beam book may include information about 4 beams based on a local scanning range (e.g., -10° to 10° based on a beam with a highest RSRP).

[0088] In operation S360, the BS 10 and the RCU 20 may control the RIS based on the beambook. The BS 10 and the RCU 20 may receive a signal for controlling the RCU, and the RCU 20 may transmit a signal for controlling the RIS to the RIS based on the acquired beambook. The RCU 20 may perform effective RIS control via the beambook generated by reflecting the hardware characteristics of the RIS.

[0089] Figure 4 1 is a flowchart for describing a method by which a BS generates a beam according to an embodiment. Figure 2 The operations are the same as those in the detailed description.

[0090] refer to Figure 4 BS10 can generate a beam based on the identified incident angle and the determined beam-related information.

[0091] In operation S410, the BS 10 may receive information about a RIS ID from the RCU 20. The RIS ID is an identifier indicating a RIS to be used by the RCU 20. The RCU 20 may determine a RIS to be used according to a beam purpose, and may identify a RIS ID corresponding to the RIS.

[0092] In operation S420, the BS 10 may identify an incident angle.

[0093] The incident angle is an angle formed by the beam transmitted from the BS 10 and the RIS and indicates an angle of departure (AoD). In an embodiment of the present disclosure, the incident angle may correspond to the RIS ID. When the BS 10 and the RIS are fixed, the BS 10 receiving information about the RIS ID may recognize the incident angle.

[0094] In operation S430, the BS 10 may determine beam-related information. The beam-related information may include information about a scanning range reflected by a beam of the RIS. In addition, the beam-related information may include beam operation information. The beam-related information may be determined based on the identified incident angle.

[0095] In operation S440, the BS 10 may generate a beam book. The beam book may be generated based on the identified incident angle and the determined beam-related information. In an embodiment of the present disclosure, when there are multiple scanning ranges to be searched by the BS 10, multiple beam books may be generated for the multiple scanning ranges. In an embodiment of the present disclosure, the BS 10 may receive information about hardware characteristics of the RIS from the RCU 20, and may generate a beam book by reflecting the information about the hardware characteristics of the RIS.

[0096] In operation S450, the BS 10 may transmit a beam book to the RCU 20. The beam book generated by the BS 10 may be transmitted to the RCU 20 to control the RIS. The BS 10 may transmit and receive a RIS control signal to and from the RCU 20 to control the RIS. In an embodiment of the present disclosure, the beam book may be transmitted through at least one of a RIS control signal or a MAC-CE.

[0097] In operation S460, the BS 10 and the RCU 20 may control the RIS based on the beambook. The BS 10 and the RCU 20 may transmit and receive a signal for controlling the RIS, and the RCU 20 may transmit a signal for controlling the RIS based on the acquired beambook.

[0098] Figure 5 1 is a flowchart for describing a method by which an RCU generates a beam when an incident angle is variable according to an embodiment. Figure 2 and Figure 3The operations are the same as those in the detailed description.

[0099] refer to Figure 5 When the incident angle is variable, the incident angle can be estimated and identified, and the RCU can generate a beam based on the identified incident angle and the determined beam-related information. When the incident angle is variable, this may include but is not limited to the case where the BS 10 has mobility or the RIS has mobility or rotation, or the case where the angle of the BS 10 or the RIS changes due to weather influences, etc.

[0100] In operation S510, the BS 10 may transmit a channel state information reference signal (CSI-RS) to the RCU 20. The CSI-RS is a reference signal for estimating an incident angle through channel estimation when the incident angle is variable.

[0101] The CSI-RS is a reference signal for estimating a channel through which the BS 10 transmits a downlink. The RCU 20 can estimate a channel between the BS 10 and the RCU 20 based on the received CSI-RS. Figure 8 Let's describe channel estimation in detail.

[0102] In an embodiment of the present disclosure, the BS10 may set an incident angle estimation period. The BS10 may set the incident angle estimation period differently according to the purpose of system operation. For example, when information needs to be updated frequently for a sharp area, the BS10 performs incident angle estimation in a short period. In an embodiment of the present disclosure, when the BS 10 or the RIS has mobility or rotation, the BS10 may set the incident angle estimation period by considering the mobile speed or the rotation periodicity. For example, when the rotation period is constant with w, the BS10 may set the same incident angle estimation period and may adjust the incident angle error caused by signal distortion.

[0103] In operation S520, the RCU 20 may estimate the incident angle. The estimation of the incident angle is based on the assumption that the boresight values ​​of the RCU 20 and the RIS are the same. Since the boresight values ​​are the same, the incident angles between the BS 10 and the RCU 20 and between the BS 10 and the RIS are the same.

[0104] In an embodiment of the present disclosure, the angle of incidence may be estimated by using the channel estimated in operation S510. RCU20 may estimate the angle of incidence by using the phase difference between adjacent antennas, which may be obtained from the channel estimated by the CSI-RS sent to RCU 20. In an embodiment of the present disclosure, the angle of incidence may be estimated by beam scanning between BS10 and RCU 20. BS10 may send beams to angle of incidence candidates to obtain an RSRP value for each beam, and may estimate the angle of the beam with the highest RSRP value as the angle of incidence. In an embodiment of the present disclosure, the angle of incidence may be estimated by using an AOA estimation algorithm through multi-antenna processing. For example, the AOA estimation algorithm may include a multiple signal classification (MUSIC) algorithm and a signal parameter estimation via rotational invariance technique (ESPRIT) algorithm. Reference will be made below to Fig.15 To describe the specific method of estimating the incident angle.

[0105] In operation S530 , the BS 10 may receive information about the incident angle from the RCU 20 .

[0106] In an embodiment of the present disclosure, the BS 10 may receive information about the incident angle identified by the estimation of the incident angle performed in operation S520. In an embodiment of the present disclosure, the BS 10 may receive multiple pieces of incident angle estimation information estimated in operation S520 to identify the incident angle. For example, when CSI-RS is used, channel information may be received; when beam scanning is used, a measured RSRP value may be received; and when the algorithm is used, a measured power value or information about the direction of arrival (DOA) may be received. The BS 10 may identify the incident angle based on multiple pieces of incident angle estimation information received from the RCU 20.

[0107] In operation S540, the BS 10 may determine beam related information. The beam related information may include information on a scanning range of an area that may be scanned by the BS through beam reflection of the RIS. In addition, the beam related information may include beam operation information. The beam related information may be determined based on the identified incident angle.

[0108] In operation S550, the BS 10 may transmit the beam-related information to the RCU 20. In detail, the BS 10 may transmit the beam-related information determined in operation S540. In an embodiment of the present disclosure, when identification of the incident angle is performed by the BS 10 based on the incident angle estimation information, information about the identified incident angle may be transmitted together with the determined beam-related information. In an embodiment of the present disclosure, the determined beam-related information and the information about the identified incident angle may be transmitted separately.

[0109] In operation S560, the RCU 20 may generate a beam book. The beam book may be generated based on the information on the identified incident angle received from the BS 10 and the determined beam-related information.

[0110] The beambook generated by the RCU 20 may reflect the hardware characteristics of the RIS. For example, the hardware characteristics of the RIS may include at least one of the size of the RIS, the RIS unit cell pattern, the RIS unit cell phase error, the specular reflection loss, or the unit cell reflection loss. In an embodiment of the present disclosure, when there are multiple scanning ranges to be searched by the BS 10, multiple beambooks may be generated for the multiple scanning ranges.

[0111] In operation S570, the BS 10 and the RCU 20 may control the RIS based on the obtained beam book. The BS 10 and the RCU 20 may transmit and receive a signal for controlling the RIS, and the RCU 20 may transmit a signal for controlling the RIS to the RIS based on the obtained beam book. The RCU 20 may perform effective RIS control via the beam book generated by reflecting the hardware characteristics of the RIS.

[0112] Figure 6 1 is a flowchart for describing a method by which a BS generates a beam when an incident angle is variable according to an embodiment. Figure 2 , Figure 4 and Figure 5 The operations are the same as those in the detailed description.

[0113] refer to Figure 6 When the incident angle is variable, the incident angle may be estimated and identified, and the BS 10 may generate a beam based on information about the identified incident angle and determined beam-related information.

[0114] In operation S610, the BS 10 may transmit a channel state information reference signal (CSI-RS) to the RCU 20. The CSI-RS is a reference signal for estimating an incident angle when the incident angle is variable.

[0115] The CSI-RS is a reference signal for estimating a channel through which the BS transmits a downlink. The RCU 20 may estimate a channel between the BS 10 and the RCU 20 based on the received CSI-RS. The BS 10 may set an incident angle estimation period.

[0116] In operation S620, the RCU 20 may estimate the incident angle. The estimation of the incident angle is based on the assumption that the boresight values ​​of the RCU 20 and the RIS are the same. Since the boresight values ​​are the same, the incident angle between the BS 10 and the RCU 20 and the incident angle between the BS 10 and the RIS are the same. The incident angle may be estimated by using a channel estimated by the CSI-RS, or may be estimated by using a beam scanning or AOA estimation algorithm.

[0117] In operation S630 , the BS 10 may receive information about the incident angle from the RCU 20 .

[0118] In an embodiment of the present disclosure, the BS 10 may receive information about the incident angle identified by the estimation of the incident angle performed in operation S620. In an embodiment of the present disclosure, the BS 10 may receive a plurality of pieces of incident angle estimation information estimated to identify the incident angle in operation S620. The BS 10 may identify the incident angle based on the plurality of pieces of incident angle estimation information received from the RCU 20.

[0119] In operation S640, the BS 10 may determine beam related information. The beam related information may include information on a scanning range of an area that may be scanned by the BS 10 through beam reflection of the RIS. In addition, the beam related information may include beam operation information. The beam related information may be determined based on the identified incident angle.

[0120] In operation S650, the BS 10 may generate a beam book. The beam book may be generated based on the identified incident angle and the determined beam-related information. In an embodiment of the present disclosure, when there are multiple scanning ranges to be searched by the BS 10, multiple beam books may be generated for the multiple scanning ranges. In an embodiment of the present disclosure, the BS 10 may receive information about hardware characteristics of the RIS from the RCU 20, and may generate a beam book by reflecting the hardware characteristics of the RIS.

[0121] In operation S660, the BS 10 may transmit a beam book to the RCU 20. The beam book generated by the BS 10 is transmitted to the RCU 20 to control the RIS. The BS 10 may transmit a RIS control signal to the RCU 20 and receive a RIS control signal from the RCU 20 to control the RIS. In an embodiment of the present disclosure, the beam book may be transmitted through at least one of a RIS control signal or a MAC-CE.

[0122] In operation S670, the BS 10 and the RCU 20 may control the RIS based on the beam book. The BS 10 and the RCU 20 may transmit and receive a signal for controlling the RIS, and the RCU 20 may transmit a signal for controlling the RIS to the RIS based on the obtained beam book.

[0123] Figure 7 FIG. 1 is a flowchart for describing an embodiment of generating a beam by reflecting a scanning range according to an embodiment. Figure 2 The operations are the same as those in the detailed description.

[0124] refer to Figure 7 , a beam book may be generated for each of a case where the scanning range is a global scanning range and a case where the scanning range is a local scanning range.

[0125] In operation S710, the BS 10 may receive information about a RIS ID from the RCU 20. The RIS ID is an identifier indicating a RIS to be used by the RCU 20. The RCU 20 may determine a RIS to be used according to a beam purpose, and may identify a RIS ID corresponding to the RIS.

[0126] In operation S715 , the BS 10 may identify an incident angle.

[0127] The incident angle is an angle formed by the beam transmitted from the BS 10 and the RIS and indicates an angle of departure (AoD). In an embodiment of the present disclosure, the incident angle may correspond to the RIS ID. When the BS 10 and the RIS are fixed, the BS receiving the information about the RIS ID may recognize the incident angle.

[0128] In operation S720, the BS 10 may transmit information about the incident angle to the RCU 20. In detail, the BS 10 may transmit information about the incident angle identified in operation S715. In an embodiment of the present disclosure, the information about the incident angle may be transmitted together with beam-related information.

[0129] In operation S725, the BS 10 may determine beam-related information including an indicator indicating that reflection for the entire area is supported. Hereinafter, for convenience of explanation, searching the entire area is referred to as global scanning.

[0130] The global scan range may be determined according to the capability of the RIS. The capability of the RIS may include the hardware characteristics of the RIS and the number of phase shift bits. The hardware characteristics of the RIS may include at least one of the size of the RIS, the RIS unit cell pattern, the RIS unit cell phase error, the mirror reflection loss, or the unit cell reflection loss. In an embodiment of the present disclosure, it may be checked whether a UE exists in a shadow area by global scanning.

[0131] In an embodiment of the present disclosure, the global scanning range may be indicated by angle information or a flag signal. For example, the global scanning range may be indicated by the capability of the RIS, such as by a minimum reflection angle (θ t，min ) to the maximum reflection angle (θ t，max) (eg, -60° to 60°). When the RCU 20 knows the global scanning range of the RIS in advance, the global scanning range may be indicated in the form of a flag signal (eg, global scanning mode=1).

[0132] The beam-related information may include beam operation information. In an embodiment of the present disclosure, the beam operation information may include at least one of the number of beams to be operated, the beam width, or the beam spacing. The beam-related information may be determined based on the identified incident angle.

[0133] In operation S730, the BS 10 may transmit beam-related information including an indicator indicating support for reflection of the entire area to the RCU 20. In detail, the BS 10 may transmit beam-related information including an indicator indicating support for global scanning determined in operation S725. In an embodiment of the present disclosure, the incident angle identified in operation S715 may be transmitted to the RCU 20 together with the beam-related information.

[0134] In operation S735, the RCU 20 may generate a first beam book. The first beam book is a beam book for scanning the entire area generated based on beam-related information including an indicator indicating that global scanning is supported and the identified incident angle.

[0135] The first beam generated in the RCU 20 may reflect the hardware characteristics of the RIS. For example, the hardware characteristics of the RIS may include at least one of the size of the RIS, the RIS unit cell pattern, the RIS unit cell phase error, the specular reflection loss, or the unit cell reflection loss.

[0136] In operation S740, RIS beam scanning may be performed based on the first beam. RIS beam scanning indicates a method of covering the entire area by changing the beam via beamforming using multiple antennas. This is a method for solving the problem of narrow cell coverage of a high frequency band by using multiple antennas. A beam may be sent to the entire area to be scanned using multiple beams via beam scanning.

[0137] In operation S745, the RCU 20 may report the result of the RIS beam scanning to the BS 10. The RCU 20 may report the result of the RIS beam scanning performed based on the first beam book to the BS 10.

[0138] In an embodiment of the present disclosure, when beam scanning is performed on the entire area based on the first beam, the RCU 20 receiving the beam may receive a response from the UE. The response from the UE may include information about the received signal strength. The RCU 20 may report to the BS 10 that the UE is located in the entire area. In an embodiment of the present disclosure, when there are multiple UEs in the entire area, the RCU 20 may report information about the beam with the maximum received signal strength or the beam with a received signal strength equal to or greater than a certain value.

[0139] In operation S750, the BS 10 may determine beam-related information including an indicator indicating that reflection to a specific area is supported. Hereinafter, for convenience of explanation, searching for a specific area is referred to as local scanning.

[0140] Based on the result received in operation S745, the local scan range may refer to a surrounding area based on a beam with a large received signal strength. For example, when there are multiple UEs in the entire area, the local scan range may be determined based on three beams with a large received signal strength among the multiple beams.

[0141] In an embodiment of the present disclosure, the local scanning range may be indicated by angle information or a flag signal. For example, the local scanning range may be indicated by angle information of -10° to 10° based on the beam with the maximum received signal strength. When the RCU 20 sets a reference signal for scanning a narrow area, the local scanning range may be indicated in the form of a flag signal (e.g., -10° to 10° = 4).

[0142] The beam-related information may include beam operation information. In an embodiment of the present disclosure, the beam operation information may include at least one of the number of beams to be operated, the beam width, or the beam spacing. The beam-related information may be determined based on the identified incident angle. In an embodiment of the present disclosure, when there are multiple local scanning ranges, the BS 10 may determine the operation information of each scanning range.

[0143] In operation S755, the BS 10 may transmit beam-related information including an indicator indicating support of reflection for a specific area to the RCU 20. In detail, the BS 10 may transmit beam-related information including an indicator indicating support of local scanning determined in operation S750. When there are multiple local scanning ranges, the indicator indicating support of local scanning may be transmitted together with operation information determined corresponding to each local scanning range.

[0144] In operation S760, the RCU 20 may generate a second beam book. The second beam book is a beam book for scanning a specific area generated based on beam-related information including a local scan range indicator and the identified incident angle.

[0145] The second beam generated in the RCU 20 may reflect the hardware characteristics of the RIS. For example, the hardware characteristics of the RIS may include at least one of the size of the RIS, the RIS unit cell pattern, the RIS unit cell phase error, or the unit cell reflection loss. In an embodiment of the present disclosure, when a plurality of local scanning ranges to be searched by the BS 10 are set, a plurality of beams for the plurality of local scanning ranges may be generated.

[0146] In operation S765, the RIS may be controlled based on the second beambook. The BS 10 and the RCU 20 may transmit and receive a signal for controlling the RIS, and the RCU 20 may transmit a signal for controlling the RIS based on the acquired beambook. The RCU 20 may perform effective RIS control via the beambook generated by reflecting the hardware characteristics of the RIS.

[0147] Figure 8 is a diagram for describing a beam transmission path using RIS according to an embodiment.

[0148] refer to Figure 8 , the beam transmitted from the BS 10 is reflected by the RIS 40 and transmitted to the UE 30. In the embodiment of the present disclosure, there may be M elements in the RIS 40. Hereinafter, for the convenience of explanation, the beam reflected by the m-th element 810 will be mainly described.

[0149] In the case of beamforming using RIS, there are two paths, namely, a first path from BS 10 to RIS 40 and a second path from RIS 40 to UE 30. In the first path, an angle (θ ) formed by a beam transmitted from BS 10 and RIS 40 is r ) is the angle of departure (AoD) and is referred to as the angle of incidence. In the second path, the angle (θ t ) is the angle of arrival (AoA) and is referred to as the reflection angle. Since there are multiple (M) RIS elements, the phase difference between the incident angles can be obtained from Equation 1, and the phase difference between the reflected angles can be obtained from Equation 2.

[0150] φ m (θ r )=exp(-j2π(m-1)d cosθ r / λ) (1)

[0151]

[0152] In the embodiment of the present disclosure, the beam spacing according to the presence of M RIS elements is referred to as d840. In the embodiment of the present disclosure, the beam spacing d840 may be set by the BS 10 to be uniform, or may be set to be non-uniform. M phases may be generated according to the M RIS elements, and b including the M phases may be generated. b=[b 1 , b 2 , …, b M ] T , and b m represents the phase of the mth element 810. During transmission to the UE, a beam localization including information of the RIS beam with the minimum data loss may be determined for each of the M phases. (opt) .

[0153]

[0154] According to Equation 3, the most effective RIS beam of the mth element 810 can be determined as According to Equation 3, the most effective RIS beam can be determined by considering the incident angle, reflection angle, scanning range, number of RIS beams, beam width and beam spacing.

[0155] Fig.9A and Fig. 9B A diagram and a flowchart for describing a system for supporting a plurality of areas by using a beamform according to an embodiment, respectively.

[0156] refer to Fig.9A According to the embodiment, the wireless communication system for performing the beam transmission method using RIS can scan multiple areas. The BS 10 and the RCU 20 can perform a process of obtaining a beam book for each of the multiple areas.

[0157] When the wireless communication system includes one BS 10 and one RCU 20, the incident angle (θ r ), but the beam-related information may be determined differently according to the operation purpose of the BS 10. In an embodiment of the present disclosure, the first area 910 may be a case where a specific area including the first UE needs to be scanned in the entire area that can be scanned by considering the capability of the RIS. For the first area, the process of obtaining the first beam book may be performed on the area including the first UE by using the local scanning range described above. For the second area 920, when scanning is required for the specific area including the second UE, the second beam book may be obtained by using the local scanning range regarding the area including the second UE. The BS may control the RIS by using the first beam book or the second beam book according to the target to be searched.

[0158] In the embodiment of the present disclosure, BS10 may have mobility. When BS10 has mobility, the incident angle (θ r ) is variable, and information about the incident angle can be obtained by estimation. When the incident angle changes, the scanning area reflected by the beam can change.

[0159] In the embodiment of the present disclosure, the RIS 40 may be mobile or rotatable. When the RIS 40 is mobile or rotatable, even if a beam is received from a fixed BS 10, the incident angle (θ r ) can also be changed. When the incident angle changes, the scanning range through beam reflection can be changed.

[0160] In the embodiment of the present disclosure, the BS 10 may have mobility, and the RIS 40 may have mobility or rotation. When the positions of both the BS 10 and the RIS 40 change, the incident angle (θ r ) is variable, therefore, the scanning range can also be changed.

[0161] refer to Fig. 9B When scanning is required for a plurality of areas, the BS 10 may perform a search for another shadow area by changing the beambook through beambook switching.

[0162] In operation S910, the BS 10 and the RCU 20 may set a first beam book for the first area 910. The process of obtaining the beam book is similar to the process of obtaining the beam book. Figures 2 to 7 The described process is the same. When the BS 10 is to perform beam scanning on the first area 910 based on the obtained first beam book, the BS 10 and the RCU 20 may set the first beam book to control the RIS.

[0163] In an embodiment of the present disclosure, the first area 910 may be an entire area scanned by using a global scan range to check whether there is a UE in a shadow area. In an embodiment of the present disclosure, the first area 910 may be a specific area scanned by using a local scan range including a specific UE.

[0164] In operation S920, the BS 10 and the RCU 20 may perform beam scanning based on the first beam book. Beam scanning refers to a method of covering the entire area by changing the beam through beam forming using multiple antennas. This is a method for solving the problem of narrow cell coverage of high frequency bands by using multiple antennas. The BS 10 and the RCU 20 may perform beam scanning by adjusting the beam interval, beam width, and scanning range based on the first beam book.

[0165] In an embodiment of the present disclosure, when the first beam is obtained based on the global scanning range, the RCU 20 may report the beam scanning result to the BS 10. As the beam scanning result, the RCU 20 may report the beam or candidate beam having the highest RSRP to the BS 10 and may determine the local scanning range.

[0166] In operation S930, the RCU 20 may perform beam book switching. When it is determined that the beam scanning for the first area 910 is completed, the RCU 20 may obtain a second beam book for the second area 920, and may perform beam switching from the first beam book to the second beam book. In an embodiment of the present disclosure, when a response signal is received from the UE, the RCU 20 may determine that the beam scanning is completed. In an embodiment of the present disclosure, when reflection of all beams is performed based on the first beam book, the RCU 20 may determine that the beam scanning is completed.

[0167] In an embodiment of the present disclosure, the RCU 20 may determine a shadow area to be searched according to an operation purpose of the BS 10, and may determine a beam source based on a scanning range and operation information.

[0168] In operation S940, the BS 10 and the RCU 20 may set a second beam book for the second area 920. The process of obtaining the second beam book is similar to the process of obtaining the second beam book. Figures 2 to 7 The described process is the same. When the BS 10 is to perform beam scanning on the second area 920 based on the obtained second beam book, the BS 10 and the RCU 20 may set the second beam book to control the RIS.

[0169] In an embodiment of the present disclosure, when a beam book for a first area 910 is obtained based on a global scan range, a second beam book for a second area 920 may be obtained based on a local scan range. The BS 10 receiving a beam report according to the beam scan based on the first beam book may obtain a second beam book for a sharp area based on a beam with a high RSRP. The specific process of obtaining a beam according to a scan range is similar to that of reference 1. Figure 7 The process described is the same.

[0170] In operation S950, the BS 10 and the RCU 20 may perform beam scanning based on the second beam book. Beam scanning refers to a method of covering a desired area by changing a beam through beamforming using multiple antennas. The BS 10 and the RCU 20 may perform beam scanning according to a beam interval, a beam width, and a scanning range of a specific area based on the second beam book.

[0171] Fig. 10A and Fig. 10B A diagram and a flowchart are respectively used to describe a system using a plurality of RIS according to an embodiment.

[0172] refer to Fig. 10A According to the embodiment, the wireless communication system for performing the beam transmission method using RIS may use a plurality of RIS. The BS 10 and the RCU 20 may perform a process of obtaining a beam book of each RIS to control the plurality of RIS.

[0173] When there are a plurality of RIS 40a, 40b, and 40c, the incident angles formed with the BS 10 may be different from each other. α ,θ β and θ γ When each incident angle is identified, the BS 10 may determine the beam-related information of each RIS according to the operation purpose. The BS 10 may obtain the beam book of each of the RIS 40a, 40b, and 40c based on the identified incident angle and the determined beam-related information. The process of obtaining the beam book is similar to that of the reference ISP. Figures 2 to 7 The process described is the same.

[0174] The BS 10 may set the operation purpose of each of the RIS 40a, 40b, and 40c differently. In an embodiment of the present disclosure, the BS 10 may obtain a beam book for scanning the entire area for one RIS, and may obtain a beam book for scanning a specific area for another RIS. In an embodiment of the present disclosure, the BS 10 may obtain multiple beam books to scan multiple areas for one RIS.

[0175] refer to Fig. 10B , when the beam transmission method is performed by using a plurality of RISs, the BS 10 may perform the beam transmission method by determining a RIS to be used.

[0176] In operation S1010, the BS 10 and the RIS 20 may set a first beam book of the first RIS. The process of obtaining the first beam book of the first RIS is similar to that of the reference numeral 1010. Figures 2 to 7 The described process is the same. When the BS 10 is to control the first RIS based on the obtained first beam book, the BS 10 and the RCU 20 may set the first beam book.

[0177] In an embodiment of the present disclosure, when there are multiple RISs, a RIS ID may be used to identify each RIS. In detail, the RCU 20 may determine the RIS to be used according to the operation purpose of the BS 10, and may identify an ID corresponding to the RIS. The RCU 20 may send the identified RIS ID to the BS 10. The BS 10 and the RCU 20 may set a beam based on the identified RIS ID.

[0178] In an embodiment of the present disclosure, the BS 10 and the RCU 20 may generate multiple beam books according to the operation purpose of one RIS. The BS 10 and the RCU 20 may determine the RSC to be used among the multiple RISs according to the system operation purpose, and may set a beam book suitable for the operation purpose from among the multiple beam books in the determined RIS.

[0179] In operation S1020, the BS 10 and the RCU 20 may perform beam scanning based on the first beam book. Beam scanning refers to a method of covering the entire area by changing the beam through beam forming using multiple antennas. This is a method for solving the problem of narrow cell coverage of a high frequency band by using multiple antennas. The BS 10 and the RCU 20 may perform beam scanning by controlling the RIS according to the beam spacing, beam width, and scanning range based on the first beam book.

[0180] In operation S1030, the RCU 20 may perform beam book switching. When it is determined that the beam scanning based on the first beam book is completed, the RCU 20 may change to the second beam book of the second RIS. In an embodiment of the present disclosure, when the RCU 20 receives a response to a signal from the UE, the RCU 20 may determine that the beam scanning is completed. In an embodiment of the present disclosure, when reflection of all beams is performed based on the first beam book, the RCU 20 may determine that the beam scanning is completed.

[0181] In an embodiment of the present disclosure, the RCU 20 may determine the RIS to be used according to the operation purpose of the BS 10, and may determine the beam based on the scanning range and operation information in the RIS.

[0182] In operation S1040, the BS 10 and the RCU 20 may set a second beam book of the second RIS. The process of obtaining the second beam book of the second RIS is similar to that of the reference numeral 1040. Figures 2 to 7 The described process is the same. When the BS 10 is to control the second RIS based on the obtained second beam book, the BS 10 and the RCU 20 may set the second beam book.

[0183] In operation S1050, the BS 10 and the RCU 20 may perform beam scanning based on the second beambook. Beam scanning refers to a method of covering a desired area by changing a beam through beamforming using multiple antennas. The BS 10 and the RCU 20 may perform beam scanning by controlling the second RIS according to a beam interval, a beam width, and a scanning range based on the second beambook.

[0184] Fig.11A and Fig. 11B A diagram and a flowchart for describing a system using a plurality of BSs according to an embodiment, respectively.

[0185] refer to Fig.11AAccording to an embodiment, a wireless communication system for performing a beam transmission method using RIS may include a plurality of BSs. Each of the plurality of BSs (eg, 10a and 10b) may obtain a beam book for controlling RIS 40.

[0186] When there are multiple BSs (e.g., 10a and 10b), the incident angle between the BS and the RIS may be different. When each incident angle is identified, each of the BSs (e.g., 10a and 10b) may determine beam-related information according to an operation purpose. Each of the BSs (e.g., 10a and 10b) may transmit and receive a control signal to and from the RCU 20 to control the RIS.

[0187] The operation purposes of the plurality of BSs (eg, 10a and 10b) may be different from each other. In an embodiment of the present disclosure, the first BS 10a may have a purpose of scanning the entire area, and the second BS 10b may have a purpose of scanning a specific area.

[0188] In an embodiment of the present disclosure, a BS (e.g., 10a and 10b) may obtain a plurality of beam books to scan a plurality of areas according to an operation purpose of one RIS 40. In an embodiment of the present disclosure, a BS (e.g., 10a and 10b) may perform a beam transmission method by sharing a plurality of RIS 40. Each BS may obtain a beam book for each of the plurality of RIS 40.

[0189] refer to Fig. 11B , when the beam transmission method is performed by using a plurality of BSs, the RCU may perform beam setting for each BS.

[0190] In operation S1110, the first BS 10a and the RCU 20 may set a first beam book for the first BS 10a. Figures 2 to 7 The described process is the same. When the RIS is to be controlled based on the obtained first beam book, the BS 10 and the RCU 20 may set the first beam book.

[0191] In operation S1120, the first BS 10a and the RCU 20 may perform beam scanning based on the first beambook. Beam scanning refers to a method of covering an entire area by changing a beam through beamforming using multiple antennas. Beam scanning is a method for solving the problem of narrow cell coverage of a high frequency band by using multiple antennas. The first BS 10a and the RCU 20 may perform beam scanning by controlling the RIS according to a beam interval, a beam width, and a scanning range based on the first beambook.

[0192] In an embodiment of the present disclosure, the first BS 10a may obtain multiple beam books to scan multiple areas. The first BS 10a may obtain multiple beam books according to beam transmission using multiple RIS. The first BS 10a may determine a beam book to be used among the multiple beam books according to a system operation purpose.

[0193] In operation S1130, the RCU 20 may perform beam book switching. When it is determined that the beam scanning based on the first beam book is completed, the RCU 20 may change to the second beam book for the second BS 10b. In an embodiment of the present disclosure, when the RCU 20 receives a response signal from the UE, the RCU 20 may determine that the beam scanning is completed. In an embodiment of the present disclosure, when reflection of all beams is performed based on the first beam book, the RCU 20 may determine that the beam scanning is completed.

[0194] In an embodiment of the present disclosure, the RCU 20 may receive a signal for RIS control from the BS 10b and may perform beam switching. In an embodiment of the present disclosure, when there are multiple RISs, the RCU 20 may determine the RIS to be used according to the operation purpose of the second BS 10b and may determine the beam according to the scanning range and operation information in the RIS.

[0195] In operation S1140, the second BS 10b and the RCU 20 may set a second beam book for the second BS 10b. Figures 2 to 7 The described process is the same. When the second BS 10b is to control the RIS, the second BS 10b and the RCU 20 may set a second beam book.

[0196] In operation S1150, the second BS 10b and the RCU 20 may perform beam scanning based on the second beam book. Beam scanning refers to a method of covering a desired area by changing a beam through beamforming using multiple antennas. The second BS 10b may perform beam sweeping by controlling the RIS according to the beam interval, beam width, and scanning range based on the obtained second beam book.

[0197] Fig.12 is a diagram for describing an example of a predetermined beam book according to an embodiment.

[0198] refer to Fig.12 , the BS 10 and the RCU 20 may control the RIS 40 using a predetermined beam. The BS 10 may receive a RIS ID corresponding to the RIS 40 to be used from the RCU 20. The RCU 20 may identify the RIS to be used according to the beam purpose, and may identify the RIS ID corresponding to the RIS.

[0199] BS10 may identify an angle of incidence, which is an angle between a beam transmitted from BS10 and RIS. In an embodiment of the present disclosure, BS10 or RIS 40 may have mobility or rotation. The angle of incidence is variable according to mobility or rotation. In order to estimate a variable angle of incidence, the angle of incidence may be identified by using a channel estimated by CSI-RS. In addition, the angle of incidence may be identified by measuring received power via beam scanning, or the angle of incidence may be identified by using an AOA estimation algorithm.

[0200] The BS 10 may determine the beam-related information according to the operation purpose. The beam-related information may include a scanning range, the number of beams, a beam width, or a beam interval. The BS 10 may determine the index of the preset beam book based on the identified incident angle and the determined operation information.

[0201] In an embodiment of the present disclosure, in the beam related information, when the scanning range of the operation information is 30° to 60° and the number of beams is 4, the candidate table 1210 may be determined in the beam book. r According to block 1220, the most effective RIS beam corresponding to the scanning range may be determined (e.g., ), and may reflect it to the UE. In an embodiment of the present disclosure, the BS 10 may determine the most effective RIS beam in the beam book by using the index of the determined beam book. In an embodiment of the present disclosure, the BS 10 may send the identified incident angle and the determined operation information to the RCU 20. The RCU 20 may determine the most effective RIS beam in the preset beam book based on the received information.

[0202] Fig.13 is a diagram for describing a scanning range according to an embodiment.

[0203] refer to Fig.13 , BS10 can determine the scanning range by using the transmitted beam. The scanning range can be determined according to the capability of the RIS. The capability of the RIS may include hardware characteristics of the RIS, the number of phase shift bits, etc. The entire area that can be scanned according to the capability of the RIS is called a global scanning range. When only a specific area is scanned according to the beam purpose in the global scanning range, the specific area is called a local scanning range.

[0204] In an embodiment of the present disclosure, the beam may perform scanning 1310 for the shadow area 1320 according to the capability of the RIS 40. The global scan may be to check whether there is a UE in the area. The scanning range may be indicated by using angle information or a flag signal. According to the global scanning range, there may be multiple UEs in the shadow area 1320.

[0205] In an embodiment of the present disclosure, the beam may perform scanning 1330 and 1350 for specific areas 1340 and 1360 according to the beam operation purpose. Local scanning may be scanning only a specific area where a UE exists and obtaining information. The scanning range may be indicated by using angle information or a flag signal.

[0206] In an embodiment of the present disclosure, BS10 and RCU 20 may obtain a first beam copy by using a global scan range, and may perform beam scanning based on the obtained first beam copy. BS10 may receive a report on the result of the beam scanning from RCU 20. Based on the report, BS10 may determine a local scan range of the surrounding area based on the beam with the highest RSRP. Alternatively, BS10 and RCU 20 may determine multiple local scan ranges of the surrounding area based on multiple beams with RSRP equal to or greater than a specific value. BS10 and RCU 20 may use local scanning to obtain a second beam copy, and may perform beam scanning based on the obtained second beam copy. The specific process is the same as reference 1. Figure 7 The process described is the same.

[0207] Fig.14 is a diagram for describing a method of estimating an incident angle according to an embodiment.

[0208] refer to Fig.14 , when the incident angle is variable, the BS 10 and the RCU 20 can estimate and identify the incident angle.

[0209] In an embodiment of the present disclosure, the incident angle may be estimated by using a channel state information reference signal (CSI-RS). The channel h may be estimated as shown in Equation 4 by using the CSI-RS transmitted from the BS 10 to the RCU 20.

[0210]

[0211] The phase difference Δφ between adjacent antennas can be obtained from the estimated channel h. The incident angle θ can be obtained from Equation 5 by using the phase difference Δφ between adjacent antennas r .

[0212]

[0213] The RCU 20 may transmit the estimated incident angle itself to the BS 10, or may transmit channel information for estimating the incident angle to the BS 10. The BS 10 may identify the incident angle θ based on the received channel information. r .

[0214] In an embodiment of the present disclosure, the estimation of the incident angle may be performed by using beam scanning. The BS 10 may measure RSRP by beam scanning to the RCU 20 and may estimate the incident angle using RSRP. In an embodiment of the present disclosure, the BS 10 may transmit N beams to estimate the incident angle θ r The RCU may measure the RSRP of each of the N beams 1410, 1420, and 1430, and may send a report on the RSRP to the BS 10. The BS 10 may estimate the angle of the beam 1420 having the highest RSRP among the multiple beams as the incident angle θ according to the received report. r In an embodiment of the present disclosure, the RCU 20 may transmit the incident angle itself according to the beam 1420 having the highest RSRP to the BS 10, or may transmit RSRP values ​​of a plurality of beams or information about the beam 1420 having the highest RSRP value. The BS 10 may identify the incident angle θ based on the received RSRP-related information. r .

[0215] In an embodiment of the present disclosure, the angle of incidence can be estimated by using an AOA estimation algorithm through multi-antenna processing. The multiple signal classification (MUSIC) algorithm is an algorithm for estimating the maximum power and direction of arrival (DOA) of a received signal by using a covariance matrix of a received signal obtained from an array antenna. For a beam sent from a BS, the RCU 20 can obtain the maximum power of the received signal and can estimate the angle of incidence. In an embodiment of the present disclosure, the RCU 20 can send the estimated angle of incidence to the BS 10 and can receive information about the maximum power of the received signal. Compared to the MUSIC algorithm, the signal parameter estimation via rotational invariance technique (ESPRIT) algorithm is a DOA estimation algorithm that has geometric limitations but computational advantages. The ESPRIT algorithm can estimate frequency and DOA by determining the parameters of a mixture of sinusoidal waves in background noise. In an embodiment of the present disclosure, the RCU 20 can estimate the angle of incidence θ r The BS 10 may transmit the incident angle itself to the BS 10, or may transmit information for estimating the incident angle. The BS 10 may recognize the incident angle based on the received information.

[0216] In an embodiment of the present disclosure, BS10 may set an incident angle estimation period. BS10 may set the incident angle estimation period differently according to the purpose of system operation. For example, when information needs to be updated frequently for a sharp area, BS10 performs incident angle estimation in a short period. In an embodiment of the present disclosure, when BS 10 or RIS has mobility or rotation, BS10 may set the incident angle estimation period by considering the mobile speed or rotation periodicity. For example, when the rotation period is constant with w, BS10 may set the same incident angle estimation period and may adjust the incident angle error caused by signal distortion. In an embodiment of the present disclosure, when the incident angle is estimated by using CSI-RS, the BS may set the incident angle estimation period by considering the periodicity of the channel. For example, the period of the channel and the incident angle estimation period may be set to be the same.

[0217] refer to Fig.15 , BS1500 may include a processor 1510, a transceiver 1520 and a memory (not shown). The transceiver 1520, the processor 1510 and the memory of BS1500 may operate according to the communication method of BS1500 described above. However, the elements of BS1500 are not limited thereto. For example, BS 1500 may include more or less elements than the elements described above. In an embodiment of the present disclosure, the transceiver 1520, the processor 1510 and the memory may be implemented as a single chip. In addition, the processor 1510 may include one or more processors.

[0218] The processor 1510 can control a series of processes so that the BS 1500 operates according to the embodiments of the present disclosure described above. For example, the processor 1510 can receive control signals and data signals through the transceiver 1520, and can process the received control signals and data signals. The processor 1510 can send the processed control signals and data signals through the transceiver 1520. In addition, the processor 1510 can write data to the memory and read data from the memory. In addition, the processor 1510 can perform the functions of the protocol stack required by the communication standard. To this end, the processor 1510 may include at least one processor or microprocessor. In an embodiment of the present disclosure, a part of the transceiver 1520 or the processor 1510 may be referred to as a communication processor (CP).

[0219] The processor 1510 may include one or more processors. In this case, the one or more processors may include a central processing unit (CPU), an application processor (AP), or a digital signal processor.

[0220] The receiver of BS1500 and the transmitter of BS1500 are collectively referred to as transceiver 1520, which can send signals to UE, RCU or network entity and receive signals from UE, RCU or network entity. In this regard, the signals sent to UE, RCU or network entity and received from UE, RCU or network entity may include control information and data. To this end, transceiver 1520 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplification and down-conversion of the frequency of the received signal. However, this is only an example of transceiver 1520, and the elements of transceiver 1520 are not limited to RF transmitters and RF receivers.

[0221] In addition, the transceiver 1520 may perform a function for transmitting and receiving signals via a wireless channel. For example, the transceiver 1520 may receive a signal through a wireless channel and output the signal to the processor 1510, and may transmit a signal output from the processor 1510 through a wireless channel.

[0222] The memory may store programs and data required for operating the BS 1500. In addition, the memory may store control information or data included in a signal obtained by the BS. The memory may include a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a compact disk (CD)-ROM, or a digital versatile disk (DVD) or any combination thereof. In addition, the memory may not exist alone, but may be included in the processor 1510. The memory may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The memory may provide stored data according to a request of the processor 1510.

[0223] Fig.16 is a block diagram schematically showing a configuration of an RCU according to an embodiment.

[0224] refer to Fig.16 According to the present disclosure, the RCU 1600 may include a processor 1610, a transceiver 1620, and a memory (not shown). However, the elements of the RCU 1600 are not limited thereto. For example, the RCU 1600 may include more or fewer elements than those described above. In an embodiment of the present disclosure, the processor 1610, the memory, and the transceiver 1620 may be implemented as a single chip.

[0225] The processor 1610 may include one or more processors. In this case, the one or more processors may include a CPU, an AP, or a digital signal processor (DSP).

[0226] The processor 1610 may control a series of processes so that the RCU 1600 operates according to the embodiments of the present disclosure described above. For example, the processor 1610 may receive control signals and data signals through the transceiver 1620, and may process the received control signals and data signals. The processor 1610 may send the processed control signals and data signals through the transceiver 1620, and may detect events. In addition, the processor 1610 may control the input data derived from the received control signals and data signals to be processed according to the predefined operation rules or artificial intelligence (AI) models stored in the memory. The processor 1610 may write data to the memory and read data from the memory. The processor 1610 may perform the functions of the protocol stack required by the communication standard. According to an embodiment, the processor 1610 may include at least one processor. In an embodiment of the present disclosure, the transceiver 1620 or a part of the processor 1610 may be referred to as a communication processor (CP). The processor 1610 may enable the RCU 1610 to perform RIS control according to the embodiments of the present disclosure described above. The processor 1610 may generate a beam for controlling RIS through communication with the BS.

[0227] The memory may store programs and data required for the operation of the RCU 1600. In addition, the memory may store control information or data included in the signal obtained by the RCU 1600. In addition, the memory may store predefined operating rules or AI models used in the RCU 1600. The memory may include a storage medium such as a ROM, RAM, hard disk, CD-ROM, or DVD, or any combination thereof. In addition, the memory may not exist alone and may be included in the processor 1610. The memory may include a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The memory may provide stored data according to a request of the processor 1610.

[0228] The transmitter and the receiver are collectively referred to as the transceiver 1620, and the transceiver 1620 of the RCU 1600 can send a signal to a BS or a network entity and receive a signal from the BS or the network entity. The signal sent or received may include control information and data. To this end, the transceiver 1620 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplification and down-conversion of the frequency of the received signal. However, this is only an example of the transceiver 1620, and the elements of the transceiver 1620 are not limited to the RF transmitter and the RF receiver. In addition, the transceiver 1620 can receive a signal through a wireless channel and output the signal to the processor 1610, and can send a signal output from the processor 1610 through a wireless channel. The transceiver 1620 can send a signal output from the processor 1610 to the BS to obtain a beam book, and can receive a signal from the BS. In addition, the transceiver 1620 can send a signal to the RIS through a wireless channel to control the RIS based on the obtained beam book.

[0229] The machine-readable storage medium may be provided as a non-transitory storage medium. Here, "non-transitory" means that the storage medium does not include a signal (e.g., an electromagnetic wave) and is tangible, but does not distinguish whether the data is stored in the storage medium semi-permanently or temporarily. For example, a "non-transitory storage medium" may include a buffer that temporarily stores data.

[0230] According to an embodiment, the method according to various embodiments of the present disclosure may be provided in a computer program product. The computer program product may be a product that can be purchased between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., a compact disc read-only memory (CD-ROM)), or distributed online (e.g., downloaded or uploaded) via an application store or distributed (e.g., downloaded or uploaded) directly between two user devices (e.g., smart phones). When distributed online, at least a portion of the computer program product (e.g., a downloadable application) may be temporarily generated or at least temporarily stored in a machine-readable storage medium, such as a memory of a manufacturer's server, an application store's server, or a relay server.

[0231] In an embodiment of the present disclosure, a method by which a BS performs communication in a wireless communication system may include receiving information about a RIS ID from a RIS control unit (RCU), which is a communication entity that reflects a beam transmitted from the BS and transmits the reflected beam to a user equipment (UE). The method may include: based on the information about the RIS ID, identifying an incident angle from the BS to the RIS corresponding to the RIS ID. The method may include determining beam-related information for scanning a preset area based on the identified incident angle, wherein the beam for RIS control in the RCU is obtained based on the identified incident angle and the determined beam-related information.

[0232] In an embodiment of the present disclosure, a method by which a BS performs communication in a wireless communication system may include transmitting a channel state information reference signal (CSI-RS) from the BS to an RCU. The method may also include receiving information related to an incident angle estimated by using the CSI-RS, wherein the incident angle is identified based on the information related to the incident angle estimated by using the CSI-RS.

[0233] In an embodiment of the present disclosure, the beam-related information may include information related to a scanning range through beam reflection by the RIS. In addition, the scanning range may be indicated by a flag signal or angle information of a beam reflection angle by the RIS.

[0234] In an embodiment of the present disclosure, based on the capability of the RIS, the information related to the scanning range may include an indicator indicating that the RIS supports reflection of the beam on the entire scanning area or an indicator indicating that the RIS supports reflection of the beam on a specific area in the entire area.

[0235] In an embodiment of the present disclosure, a method by which a BS performs communication in a wireless communication system may include obtaining a first beam book for scanning an entire area based on an indicator indicating that a reflection of a beam is supported for an entire scanning area. The method may also include obtaining a second beam book for scanning a specific area based on an indicator indicating that a reflection of a beam is supported for a specific area in the entire area.

[0236] In an embodiment of the present disclosure, the beam-related information may include information on at least one of the number of beams set by the BS, the width of the beam reflected by the RIS, or the beam interval.

[0237] In an embodiment of the present disclosure, the method by which the BS performs communication in the wireless communication system may further include generating a beam book based on the identified incident angle and the determined beam-related information, and transmitting the generated beam book to the RCU.

[0238] In an embodiment of the present disclosure, the method by which the BS performs communication in the wireless communication system may also include sending the identified incident angle and determined beam-related information to the RCU, wherein the beam is generated based on the identified incident angle and determined beam-related information in the RCU.

[0239] In an embodiment of the present disclosure, the method by which the BS performs communication in the wireless communication system may also include, in a case where beam books are respectively obtained for multiple RISs controlled by the RCU, setting a beam book for the RIS to be used by the BS from among the beam books for the multiple RISs.

Claims

1. A method for a base station (BS) to perform communication in a wireless communication system, the method comprising: receiving information about a reconfigurable smart surface (RIS) identification (ID) from a RIS control unit (RCU), the RIS control unit (RCU) being a communication entity that controls the RIS, the RIS reflecting a beam transmitted from a BS and transmitting the reflected beam to a user equipment (UE); Based on the information about the RIS ID, identifying an incident angle from the BS to the RIS corresponding to the RIS ID; as well as Based on the identified incident angle, determining beam-related information for scanning a preset area, Therein, a beam for RIS control in the RCU is obtained based on the identified incident angle and determined beam-related information.

2. The method according to claim 1, further comprising: Sending a channel state information reference signal (CSI-RS) to the RCU; as well as receiving information related to an incident angle estimated by using a CSI-RS, Here, the incident angle is identified based on information related to the incident angle estimated by using the CSI-RS.

3. The method according to claim 1 or 2, wherein: The beam-related information includes information related to the scanning range through the beam reflection by the RIS, The scanning range is indicated by the angle information of the reflection angle of the marker signal or the beam of the RIS.

4. The method according to claim 3, wherein: Information related to the scan range includes: an indicator indicating that the RIS supports beam reflection for the entire scan area, or Indicator indicating that based on the capability of RIS, RIS supports beam reflection to a specific area in the whole area, Wherein, the method further comprises: Based on the indicator indicating that beam reflection for the entire scanning area is supported, obtaining a first beam book for scanning the entire area; and Based on the indicator indicating that beam reflection to a specific area among the entire area is supported, a second beam book for scanning the specific area is obtained.

5. The method according to any one of claims 1 to 4, wherein: The beam-related information includes information on at least one of the number of beams set by the BS, the width of the beam reflected by the RIS, and the beam interval.

6. The method according to any one of claims 1 to 5, further comprising: generating a beam based on the identified incident angle and the determined beam-related information; as well as The generated beam book is sent to the RCU.

7. The method according to any one of claims 1 to 6, further comprising: The identified incident angle and the determined beam-related information are sent to the RCU, The beam is generated based on the identified incident angle and the determined beam-related information in the RCU.

8. The method according to any one of claims 1 to 7, further comprising: In the case where beam books are respectively obtained for a plurality of RISs controlled by the RCU, a beam book for the RIS to be used by the BS is set from among the beam books for the plurality of RISs.

9. A base station (BS) for performing communication in a wireless communication system, the BS comprising: Transceiver; as well as At least one processor, coupled to the transceiver and configured to: receiving information about a RIS identification (ID) from a RIS control unit (RCU), the RIS control unit (RCU) being a communication entity that controls the RIS, the RIS reflecting a beam transmitted from a BS and transmitting the reflected beam to a user equipment (UE), Based on the information about the RIS ID, identifying the incident angle from the BS to the RIS corresponding to the RIS ID, and Based on the identified incident angle, determining beam-related information for scanning a preset area, Therein, a beam for RIS control in the RCU is obtained based on the identified incident angle and determined beam-related information.

10. The BS according to claim 9, wherein: The at least one processor is further configured to: Sending a channel state information reference signal (CSI-RS) to the RCU, and receiving information related to an incident angle estimated by using a CSI-RS, Here, the incident angle is identified based on information related to the incident angle estimated by using the CSI-RS.

11. The BS according to claim 9 or 10, wherein: The beam-related information includes information related to a scanning range by reflection of the beam by the RIS. The scanning range is indicated by the angle information of the reflection angle of the marker signal or the beam of the RIS.

12. The BS according to any one of claims 9 to 11, wherein: The beam-related information includes information on at least one of the number of beams set by the BS, the width of the beam reflected by the RIS, and the beam interval.

13. The BS according to any one of claims 9 to 12, wherein: The at least one processor is further configured to: generating a beam based on the identified incident angle and the determined beam-related information; and The generated beam book is sent to the RCU.

14. The BS according to any one of claims 9 to 13, wherein: The at least one processor is further configured to send the identified incident angle and the determined beam-related information to the RCU, The beam is generated based on the identified incident angle and the determined beam-related information in the RCU. 15 . A computer-readable recording medium having recorded thereon a program for executing the method according to claim 1 on a computer.

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