Method and apparatus for determining RIS association in wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting a data rate higher than that of a 4G communication system such as Long Term Evolution (LTE). According to one embodiment of the present disclosure, a method performed by a terminal in a wireless communication system is provided. The method comprises the steps of: receiving information on a first beam set and a second beam set and information on a first threshold value from a base station; determining whether the terminal is in a reconfigurable intelligent surface (RIS) association based on measurement results of the first beam set and the second beam set and the first threshold; and transmitting, to the base station, information indicating whether the terminal is in the RIS association. Beam scanning is performed based on one of the first set of beams and the second set of beams depending on whether the terminal is in the RIS association.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for efficient data transmission of a base station and a terminal in a sixth generation mobile communication (6G) system. Background Art

[0002] As wireless communication technology has evolved over generations, it has primarily focused on providing human services such as voice calls, multimedia services, and data services. With the commercialization of 5G (fifth-generation) communication systems, the number of connected devices is expected to grow exponentially, with an increasing number of devices connected to communication networks. Examples of connected devices include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructure, construction machinery, and factory equipment. Mobile devices are expected to evolve into various forms, such as augmented reality glasses, virtual reality headsets, and holographic devices. To provide a variety of services in the 6G (sixth-generation) era by connecting hundreds of billions of devices and items, efforts are underway to develop improved 6G communication systems. Consequently, 6G communication systems are being referred to as systems beyond 5G.

[0003] The 6G communication system, which is expected to be commercialized around 2030, will have a peak data rate of terabit (1000 gigabits) per second and a wireless delay of less than 100 microseconds, so its speed will be 50 times that of the 5G communication system and the wireless delay will be 1 / 10 of that.

[0004] To achieve such high data rates and ultra-low latency, 6G communication systems are being considered in the terahertz (THz) frequency band (e.g., 95 GHz to 3 THz). Because the THz band suffers from more severe path loss and atmospheric absorption than the millimeter-wave (mmW) band introduced in 5G, technologies that ensure signal transmission distance (i.e., coverage) are expected to become even more critical. Key technologies for ensuring coverage include radio frequency (RF) components, antennas, new waveforms with improved coverage compared to 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. Furthermore, new technologies to improve THz signal coverage are under ongoing discussion, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS).

[0005] Furthermore, to improve spectrum efficiency and overall network performance, the following technologies are being developed for 6G communication systems: full-duplex technology that enables uplink and downlink transmissions to use the same frequency resources simultaneously; network technologies that integrate and utilize satellites, high-altitude platform stations (HAPS), and other technologies; improved network architectures that support mobile base stations and achieve network operation optimization and automation; dynamic spectrum sharing technology that avoids conflicts based on spectrum usage prediction; the application of artificial intelligence (AI) in wireless communications by leveraging the design phase of 6G development and integrating end-to-end AI support to improve overall network operation; and next-generation distributed computing technologies that overcome the computing power limitations of UEs through network-accessible ultra-high-performance communication and computing resources such as mobile edge computing (MEC) and the cloud. Furthermore, efforts are ongoing to strengthen device connectivity, optimize networks, promote the softwareization of network entities, and enhance the openness of wireless communications by designing new protocols for 6G communication systems, developing hardware-based security environments and mechanisms for secure data use, and developing technologies to maintain privacy.

[0006] Research and development of 6G communication systems are expected to usher in the next generation of hyperconnected experiences, encompassing both human-to-machine (P2M) and machine-to-machine (M2M) connectivity. Specifically, 6G communication systems are expected to enable services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, services such as remote surgery, industrial automation, and emergency response for enhanced safety and reliability will also be enabled by 6G communication systems, enabling the application of these technologies in various fields, including industry, healthcare, automotive, and home appliances.

[0007] Meanwhile, reconfigurable smart surfaces (RIS) are reflective panels or antennas that can respond to real-time changes in the wireless environment and dynamically control propagation paths in the absence of line-of-sight (LoS) links. RIS consists of reflective elements (REs) contained within a reflective plane, which can control the reflection, refraction, and absorption of incident radio waves by forming a reflection pattern defined by the phase and / or amplitude combination of the radio waves. Summary of the Invention

[0008] Technical issues

[0009] In 5G / 6G systems, the use of high frequency bands increases the technical requirements for compensating for path loss. One aspect of the present disclosure is to allow a terminal and / or base station in a wireless communication system to determine a RIS association, thereby operating the system more efficiently.

[0010] Technical Solution

[0011] According to an embodiment of the present disclosure, a method performed by a terminal in a wireless communication system is provided. The method includes: receiving information about a first beam set and a second beam set and information about a first threshold from a base station; determining whether the terminal is associated with a reconfigurable smart surface (RIS) based on measurement results for the first beam set and the second beam set and the first threshold; and transmitting information indicating whether the terminal is associated with the RIS to the base station. Beam scanning is performed based on one of the first beam set and the second beam set, depending on whether the terminal is associated with the RIS.

[0012] According to an embodiment of the present disclosure, a method performed by a base station in a wireless communication system is provided. The method includes: transmitting information about a first beam set and a second beam set to a terminal; receiving measurement results for the first beam set and the second beam set from the terminal; and determining whether the terminal is in a RIS association based on the measurement results and a predetermined threshold. Beam scanning is performed based on one of the first beam set and the second beam set, depending on whether the terminal is in the RIS association.

[0013] According to an embodiment of the present disclosure, a terminal in a wireless communication system is provided. The terminal includes a transceiver and a controller. The controller is configured to control the transceiver to receive information about a first beam set and a second beam set and information about a first threshold from a base station; determine whether the terminal is in a RIS association based on measurement results for the first beam set and the second beam set and the first threshold; and control the transceiver to send information indicating whether the terminal is in the RIS association to the base station. Beam scanning is performed based on one of the first beam set and the second beam set, depending on whether the terminal is in the RIS association.

[0014] According to an embodiment of the present disclosure, a base station in a wireless communication system is provided. The base station includes a transceiver and a controller. The controller is configured to control the transceiver to transmit information about a first beam set and a second beam set to a terminal; control the transceiver to receive measurement results for the first beam set and the second beam set from the terminal; and determine whether the terminal is in a RIS association based on the measurement results and a predetermined threshold. Beam scanning is performed based on one of the first beam set and the second beam set, depending on whether the terminal is in the RIS association.

[0015] Beneficial effects

[0016] According to the embodiments of the present disclosure, a terminal and / or a base station may identify whether the terminal is in a RIS association, thereby operating a wireless communication system more efficiently.

[0017] According to an embodiment of the present disclosure, a network may reduce reference signal overhead of a terminal in a RIS association by configuring a terminal (UE)-specific reference signal.

[0018] According to an embodiment of the present disclosure, when a terminal is in a RIS association, the network can improve performance gain by reducing the interval between beams used for beam management.

[0019] The beneficial effects obtainable from the present disclosure are not limited to the above-mentioned effects, and those skilled in the art can clearly understand other effects not mentioned herein from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 shows a scenario in which a terminal is located outside a shadow area in a wireless communication system including a RIS; Figure 2 shows a scenario in which a terminal is located inside a shadow area in a wireless communication system including a RIS; Figure 3 An example of a configuration for determining a synchronization signal set associated with a RIS according to an embodiment of the present disclosure is shown; Figure 4 Another configuration example for determining a synchronization signal set associated with a RIS according to an embodiment of the present disclosure is shown; Figure 5 FIG. 1 shows a synchronization signal having a maximum RSRP value in each synchronization signal set for determining a RIS association according to an embodiment of the present disclosure; Figure 6 A timing diagram showing a method for a base station to determine RIS association based on a synchronization signal measurement value when a terminal initially accesses according to an embodiment of the present disclosure is shown; Figure 7 A timing diagram showing a method for a terminal to determine RIS association based on a synchronization signal measurement value during initial access according to an embodiment of the present disclosure is shown; Figure 8 A timing diagram illustrating a method in which a base station determines a RIS association based on an RS measurement value of a terminal in a connected mode according to an embodiment of the present disclosure; Figure 9 A timing diagram illustrating a method for a terminal in a connected mode to determine a RIS association based on an RS measurement value according to an embodiment of the present disclosure is shown; Figure 10 The structure of the UE according to an embodiment of the present disclosure is shown; Figure 11 The structure of a base station according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0022] When describing the embodiments, descriptions related to well-known technologies in the related art and not directly related to the present disclosure will be omitted.

[0023] Such omission of unnecessary description is intended to avoid obscuring the main points of the present disclosure and to convey the main points more clearly.

[0024] For the same reason, in the accompanying drawings, some elements may be amplified, omitted or schematically shown. In addition, the size of each element does not fully reflect the actual size. In each of the accompanying drawings, identical or corresponding elements are given identical or similar reference numerals.

[0025] The advantages and features of the present disclosure and their implementation will become more apparent from the embodiments described in detail below with reference to the accompanying drawings.

[0026] However, the present disclosure is not limited to the following embodiments, but can be implemented in various forms. The present embodiment is provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the appended claims. Throughout the specification, the same or similar reference numerals represent the same or similar elements.

[0027] It should be understood that each block in the flowchart illustration, as well as combinations of blocks in the flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, thereby generating a machine, such that the instructions executed by the processor of the computer or other programmable data processing device create a device for implementing the functions specified in the flowchart blocks. These computer program instructions can also be stored in a computer-usable or computer-readable memory, which can direct the computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-usable or computer-readable memory produce an article of manufacture including instruction means for implementing the functions in the flowchart blocks. The instructions executed on the computer or other programmable data processing device can perform a series of operational steps on the computer or other programmable data processing device, thereby generating a computer-implemented process, such that the instructions executed on the computer or other programmable data processing device provide steps for implementing the functions in the flowchart blocks.

[0028] In addition, each block in the flowchart diagram may represent a code module, code segment, or code portion containing one or more executable instructions for implementing a specified logical function. It should be noted that in some alternative implementations, the functions noted in the blocks may occur in a different order. For example, two blocks shown in succession may actually be executed substantially in parallel, or may sometimes be executed in reverse order depending on the functions involved.

[0029] As used in the embodiments of the present disclosure, the term "unit" refers to a software element or a hardware element, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and a "unit" can perform a specific function. However, the meaning of "unit" is not always limited to software or hardware. A "unit" can be configured to be stored in an addressable storage medium or executed on one or more processors. Therefore, a "unit" includes, for example, a software element, an object-oriented software element, a class element, or a task element, a process, a function, a property, a program, a subroutine, a program code segment, a driver, firmware, microcode, a circuit, data, a database, a data structure, a table, an array, and a parameter. The elements and functions provided by a "unit" can be combined into fewer elements or units, or divided into more elements or units. In addition, elements and "units" can replicate one or more CPUs in a device or secure multimedia card. Furthermore, a "unit" in the embodiments may include one or more processors.

[0030] In the following description, for convenience, some terms and names defined in the Third Generation Partnership Project (3GPP) standards (standards for 5G, NR, Long Term Evolution (LTE), or similar systems) may be used. Furthermore, terms and names used in existing communication systems to which the present disclosure applies, or newly defined terms and names in next-generation communication systems (e.g., 6G systems and beyond 5G systems), may also be used. The use of these terms and names is not intended to limit the present disclosure, and the present disclosure can be applied in the same manner to systems conforming to other standards and can be modified into other forms without departing from the technical concepts of the present disclosure.

[0031] As used in the embodiments of the present disclosure, it should be understood that the singular expression "the" also includes the plural expression unless the context clearly indicates otherwise.

[0032] As used in the embodiments of the present disclosure, terms including ordinal numbers (such as "first" and "second") may be used to describe various elements, but the corresponding elements should not be limited by these terms. The above terms are only used to distinguish one element from other elements. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of protection of the present disclosure.

[0033] As used in the embodiments of the present disclosure, the term "and / or" includes any one or combination of the listed multiple related items.

[0034] The terms used in the embodiments of the present disclosure are only used to describe specific embodiments and are not intended to limit the present disclosure. Singular expressions may include plural expressions unless they are clearly different in context. As used herein, the expression "including" or "having" is intended to specify the presence of the mentioned features, quantities, steps, operations, elements, components or combinations thereof, and should be interpreted as not excluding the possible presence or addition of one or more other features, quantities, steps, operations, elements, components or combinations thereof.

[0035] As used in the present disclosure, the expression “greater than” or “less than” is used to determine whether a specific condition is satisfied, but this is intended to illustrate examples only and does not exclude “greater than or equal to” or “equal to or less than.” A condition indicated by the expression “greater than or equal to” may be replaced by a condition indicated by “greater than,” a condition indicated by the expression “equal to or less than” may be replaced by a condition indicated by “less than,” and a condition indicated by “greater than and equal to or less than” may be replaced by a condition indicated by “greater than and less than.”

[0036] Before describing the present disclosure in detail, examples of the interpretable meanings of some terms used herein are given below. However, it should be noted that these terms are not limited to the examples of the interpretable meanings given below.

[0037] In the present disclosure, a terminal (or communication terminal) is an entity that communicates with a base station or any other terminal and may be referred to as a node, user equipment (UE), next generation UE (NG UE), mobile station (MS), device, terminal, etc. A terminal may include at least one of a smartphone, a tablet computer (PC), a mobile phone, a video phone, an e-book reader, a desktop PC, a laptop PC, a netbook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), an MP3 player, a medical device, a camera, and a wearable device. Furthermore, a terminal may include at least one of a television, a digital video disc (DVD) player, an audio device, a refrigerator, an air conditioner, a vacuum cleaner, an oven, a microwave oven, a washing machine, an air purifier, a set-top box, a home automation control panel, a security control panel, a media box, a game console, an electronic dictionary, an electronic key, a camera, and an electronic photo frame. Furthermore, a terminal may include at least one of various medical devices (e.g., various portable medical measurement devices (blood glucose monitoring devices, heart rate monitoring devices, blood pressure measurement devices, body temperature measurement devices, etc.), magnetic resonance angiography (MRA), magnetic resonance imaging (MRI), computed tomography (CT) machines, ultrasound machines, etc.), navigation equipment, global positioning system (GPS) receivers, event data recorders (EDRs), flight data recorders (FDRs), vehicle infotainment equipment, marine electronic equipment (e.g., marine navigation equipment, gyrocompasses, etc.), avionics equipment, security equipment, automotive head units, home or industrial robots, drones, automated teller machines (ATMs) in banks, point-of-sale (POS) devices in stores, or IoT devices (e.g., light bulbs, various sensors, electricity or gas meters, sprinklers, fire alarms, thermostats, streetlights, toasters, sports equipment, hot water tanks, heaters, boilers, etc.). Furthermore, a terminal may include various multimedia systems with communication capabilities. The present disclosure is not limited to the above examples, and a terminal may also be referred to by terms having the same or similar meanings.

[0038] In the present disclosure, a base station is an entity that communicates with a terminal and allocates resources to the terminal, and may be referred to as a base station (BS), a node B (NB), a next-generation radio access network (NG RAN), an access point (AP), a transmission reception point (TRP), a radio access unit, a base station controller, a node on a network, etc. Alternatively, depending on the functional separation, a base station may be referred to as a central unit (CU) or a distributed unit (DU). However, the present disclosure is not limited to the above examples, and a base station may also be referred to by terms having the same or similar meanings.

[0039] As used herein, control information may be referred to as a control message or control signaling depending on the context, or may be referred to as a medium access control (MAC) control element (CE), downlink control information (DCI), uplink control information (UCI), or radio resource control (RRC) message, and the present disclosure is not limited to the above examples, and control information may also be referred to by terms having the same or similar meanings.

[0040] As used herein, transmitting a physical channel (e.g., a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), or a physical uplink shared channel (PUSCH)) may mean transmitting a signal (or data) via the corresponding physical channel. In the present disclosure, for example, transmitting or receiving a PDCCH may mean transmitting or receiving a signal (e.g., DCI) via the PDCCH. Alternatively, transmitting or receiving a PDSCH may mean transmitting or receiving a signal (e.g., downlink data) via the PDSCH. Alternatively, transmitting or receiving a PUCCH may mean transmitting or receiving a signal (e.g., UCI) via the PUCCH. Alternatively, transmitting or receiving a PUSCH may mean transmitting or receiving a signal (e.g., uplink data) via the PUSCH.

[0041] Traditional wireless communication systems are designed to compensate for the wireless environment by optimizing transmitting and receiving nodes. However, with recent advances in wireless communication technology, research is underway to design systems capable of real-time control of the wireless environment. Wireless environments constructed using this approach can be referred to as intelligent radio environments (SRE / IRE). Various terms have been proposed for technologies implementing SRE, including reconfigurable metasurfaces, smart large-scale intelligent surfaces (SLIS), large-scale intelligent surfaces (LIS), reconfigurable intelligent surfaces (RIS), and intelligent reflective surfaces (IRS). In this disclosure, the term RIS is primarily used to describe this technology.

[0042] Reconfigurable smart surfaces (RIS) are reflective panels or antennas that can respond to real-time changes in the wireless environment and control propagation paths in real time without a line-of-sight (LoS) link. RIS consists of reflective elements (REs) embedded in a reflective plane and can control the reflection, refraction, and absorption of radio waves reaching the RIS by forming a reflection pattern defined by the phase and / or amplitude combination of the radio waves.

[0043] Figure 1 A scenario is shown in which a UE is located outside a shadow area in a wireless communication system including a RIS.

[0044] In the present disclosure, an area where the strength of a signal transmitted from a base station is significantly attenuated due to blocking in a wireless communication system may be defined as a shadow area.

[0045] refer to Figure 1 , when UE 110 is outside of shadow area 130, UE 110 and base station 100 may operate in a manner of directly transmitting and receiving signals to and from each other. Figure 1 As shown, if UE 110 is located outside shadow area 130 , even if a signal to which a reflection mode is applied is transmitted and received through RIS 120 , the strength of the signal transmitted and received through RIS 120 may be similar to the strength of the signal directly transmitted and received from base station 100 .

[0046] Figure 2 A scenario is shown in which a UE is located inside a shadow area in a wireless communication system including a RIS.

[0047] refer to Figure 2 , when the UE 110 is located inside the shadow area 130, the UE 110 may transmit and receive signals to which the reflection mode is applied by the RIS 120. Figure 2 As shown, if UE 110 is located within shaded area 130, the strength of signals directly transmitted and received between UE 110 and base station 100 may be low due to obstruction, while the strength of signals transmitted and received via RIS 120 may be high. As described above, the state in which UE 110 is located within shaded area 130, whereby signals directly transmitted and received from base station 100 are attenuated and signals with a reflection pattern applied by RIS 120 are transmitted and received, can be defined as the UE being in RIS association. Furthermore, the state of being in RIS association may also be referred to as "RIS on," and the state of not being in RIS association may also be referred to as "RIS off."

[0048] At the same time, the signal applied by the reflection pattern of RIS 120 may be measured as the strongest both when UE 110 is outside shadow area 130 and when UE 110 is inside shadow area 130. Therefore, the present disclosure provides a method by which a UE and / or a base station determines a RIS association based on the above background, thereby enabling the system to operate more efficiently.

[0049] For example, the number of beams a base station can operate can be defined as M, and the number of reflection modes operated via RIS can be defined as K. If it is unknown whether the UE is associated with RIS, beam management may require the use of M+K reference signals (RS). Here, RS can be a channel state information reference signal (CSI-RS), a synchronization signal block (SSB), a sounding reference signal (SRS), or a newly defined reference signal. If it is determined whether the UE is associated with RIS, the following operations can be performed.

[0050] First, if the UE is not in RIS association and transmits and receives signals directly with the base station, the base station can configure the RS so that the UE only scans the beam set transmitted directly from the base station. In the above example, the base station can configure up to M RSs.

[0051] Secondly, if the UE is associated with a RIS and therefore transmits and receives signals that use a reflection pattern applied by the RIS, the base station can configure the RS so that the UE scans only the reflection pattern of the RIS or only the beam set corresponding to the reflection pattern. In the above example, the base station can configure up to K RSs. In this case, performance gains can be improved by reducing the spacing between beams used for beam management.

[0052] The following describes a method for determining RIS association during initial access.

[0053] According to an embodiment of the present disclosure, a synchronization signal (or SSB, hereinafter used interchangeably) for determining RIS association at the time of initial access may be configured.

[0054] Figure 3 A configuration example for determining a synchronization signal set associated with a RIS according to an embodiment of the present disclosure is shown.

[0055] refer to Figure 3 , the base station may operate SSB by separating an SSB set 300 (hereinafter referred to as beam set 1) associated with a beam transmitted directly from the base station and an SSB set 310 (hereinafter referred to as beam set 2) associated with a reflection pattern of the RIS (or a beam corresponding to the reflection pattern).

[0056] In an example, the base station may explicitly indicate to the UE for each SSB whether the SSB is included in beam set 1 300 or beam set 2 310 .

[0057] For example, the base station may include information in the form of a bitmap indicating the RIS association of the SSB in the physical broadcast channel (PBCH) payload or the master information block (MIB) and send the information to the UE. In the bitmap, the SSB corresponding to beam set 1 300 is indicated as "0", and the SSB corresponding to beam set 2 310 is indicated as "1". Figure 3 As shown, the bitmap is set to {01001110} and can be sent to the UE through the PBCH payload or MIB. Alternatively, the SSB corresponding to beam set 1 300 in the bitmap is indicated as "1" and the SSB corresponding to beam set 2 310 is indicated as "0". Figure 3 As shown, the bitmap is set to {10110001} and can be sent to the UE through the PBCH payload or MIB.

[0058] As another example, a pattern configured by a combination of beam set 1 300 and beam set 2 310 may be predefined, and the base station may transmit a PBCH payload or MIB containing information indicating one of the predefined patterns to the UE.

[0059] As another example, a pattern configured by a combination of beam set 1 300 and beam set 2 310 may be predefined, and the base station may transmit downlink control information (DCI) including information indicating one of the predefined patterns to the UE. Alternatively, a pattern configured by a combination of beam set 1 300 and beam set 2 310 may be predefined, and the base station may transmit a PBCH payload or MIB including information indicating at least one candidate pattern among the predefined patterns to the UE, and then transmit DCI including information indicating one of the at least one candidate pattern to the UE.

[0060] Figure 4 Another configuration example for determining a RIS-associated synchronization signal set according to an embodiment of the present disclosure is shown.

[0061] refer to Figure 4 , the base station can operate SSB by separating a synchronization signal set 400 associated with a beam transmitted directly from the base station (hereinafter referred to as beam set 1) and a synchronization signal set 410 associated with a reflection pattern of RIS (or a beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2).

[0062] In one example, the base station may indicate to the UE the time point at which beam set 1 400 and beam set 2 410 are separated from each other.

[0063] For example, the base station may send 1-bit information to the UE through the MIB, where the information is flipped at the time when beam set 1 400 changes to beam set 2 410 (or beam set 2 410 changes to beam set 1 400).

[0064] As another example, the base station may transmit N bits of information through the MIB, which indicates the SSB index before or after changing from beam set 1 400 to beam set 2 410 (or changing from beam set 2 410 to beam set 1 400). Here, when the total number of SSBs included in beam set 1 400 and beam set 2 410 is N ssb When , the value of N can be shown as in the following equation 1.

[0065] (Equation 1)

[0066] As another example, the base station may transmit N bits of information through the PBCH payload or system information block 1 (SIB 1), indicating the SSB index before or after changing from beam set 1 400 to beam set 2 410 (or from beam set 2 410 to beam set 1 400). Here, the value of N may be as shown in Equation 1 above.

[0067] As another example, the base station may transmit N-bit information through DCI (e.g., DCI format 1_0), indicating the SSB index before or after changing from beam set 1 400 to beam set 2 410 (or from beam set 2 410 to beam set 1 400). Here, the value of N may be as shown in Equation 1 above.

[0068] In the example, the locations of beam set 1 400 and beam set 2 410 are predefined in the specification, and SSBs can be transmitted at the predefined locations. The UE can select an SSB for synchronization and determine the index of the selected SSB and which beam set the SSB corresponds to.

[0069] According to an embodiment of the present disclosure, the base station may determine whether the UE is in RIS association based on a synchronization signal measurement value when the UE initially accesses.

[0070] Figure 5 The synchronization signal having the maximum RSRP value in each synchronization signal set used to determine the RIS association according to an embodiment of the present disclosure is shown.

[0071] By reference Figure 3 and Figure 4 The described method can configure a synchronization signal set 500 associated with a beam transmitted directly from a base station (hereinafter referred to as beam set 1) and a synchronization signal set 510 associated with a reflection pattern of a RIS (or a beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2) for a UE.

[0072] In this example, the UE may measure the SSB of beam set 1 500 to derive a maximum reference signal received power (RSRP) value 501. Furthermore, the UE may measure the SSB of beam set 2 510 to derive a maximum RSRP value 511. The UE may report two maximum RSRP values 501 and 511 corresponding to beam set 1 500 and beam set 2 510, respectively, to the base station. The UE may report these two maximum RSRP values 501 and 511 to the base station via the physical uplink shared channel (PUSCH) of message 3 (Msg 3) during the random access procedure. The base station may determine whether the UE is in a RIS association based on the two maximum RSRP values 501 and 511 received from the UE. For example, if the maximum RSRP value 501 corresponding to beam set 1 500 is greater than (or greater than or equal to) the maximum RSRP value 511 corresponding to beam set 2 510, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value 511 corresponding to beam set 2 510 is greater than (or greater than or equal to) the maximum RSRP value 501 corresponding to beam set 1 500, the base station may calculate the difference between the two maximum RSRP values 501 and 511. Thereafter, if the difference is greater than (or greater than or equal to) a specific threshold for determining RIS association, the base station may determine that the UE is in RIS association. The threshold may be a predefined fixed value and may vary depending on the time point at which the RIS association is determined.

[0073] In this example, the UE may measure the SSB of beam set 1 500 to derive an RSRP value exceeding a first threshold. Furthermore, the UE may measure the SSB of beam set 2 510 to derive an RSRP value exceeding a second threshold. The first and second thresholds may be equal or different. Furthermore, the first and second thresholds may be preconfigured for the UE via the PBCH payload, MIB, or SIB1. The UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 500 and the RSRP value exceeding the second threshold for beam set 2 510. In this case, the UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 500 and the RSRP value exceeding the second threshold for beam set 2 510 via the PUSCH in Msg 3 during the random access procedure. The base station may differentiate the RSRP values received from the UE for each beam set and then derive the two maximum RSRP values 501 and 511 corresponding to beam set 1 500 and beam set 2 510, respectively. The base station can determine whether the UE is in a RIS association based on the two derived maximum RSRP values 501 and 511. For example, if the maximum RSRP value 501 corresponding to beam set 1 500 is greater than (or greater than or equal to) the maximum RSRP value 511 corresponding to beam set 2 510, the base station can determine that the UE is not in a RIS association. For example, if the maximum RSRP value 511 corresponding to beam set 2 510 is greater than (or greater than or equal to) the maximum RSRP value 501 corresponding to beam set 1 500, the base station can calculate the difference between the two maximum RSRP values 501 and 511. Thereafter, if this difference is greater than (or greater than or equal to) a third threshold for determining RIS association, the base station can determine that the UE is in a RIS association. The third threshold can be a predefined fixed value and can vary depending on the time point when the RIS association is determined.

[0074] According to an embodiment of the present disclosure, the UE may determine the RIS association based on a synchronization signal measurement value during initial access.

[0075] refer to Figure 5 , the UE may measure the SSB of beam set 1 500 to obtain a maximum RSRP value 501. In addition, the UE may measure the SSB of beam set 2 510 to obtain a maximum RSRP value 511.

[0076] The UE can determine RIS association based on the two derived maximum RSRP values 501 and 511. For example, if the maximum RSRP value 501 corresponding to beam set 1 500 is greater than (or greater than or equal to) the maximum RSRP value 511 corresponding to beam set 2 510, the UE can determine that the UE is not RIS associated. For example, if the maximum RSRP value 511 corresponding to beam set 2 510 is greater than (or greater than or equal to) the maximum RSRP value 501 corresponding to beam set 1 500, the UE can calculate the difference between the two maximum RSRP values 501 and 511. Thereafter, if this difference is greater than (or greater than or equal to) a specific threshold for determining RIS association, the UE can determine that the UE is RIS associated. This threshold can be a predefined fixed value, can vary depending on the time point of determining RIS association, or can be configured by the base station via the PBCH payload or MIB.

[0077] Thereafter, the UE may report to the base station whether the UE is in RIS association.

[0078] For example, the UE may transmit at least one of the maximum RSRP value 501 corresponding to beam set 1 500, the maximum RSRP value 511 corresponding to beam set 2 510, and information indicating whether the UE is in RIS association to the base station through the PUSCH of Msg 3 in the random access procedure.

[0079] As another example, the UE may transmit information indicating whether the UE is in a RIS association to the base station via a random access channel (RACH) resource. Here, the RACH resource may be mapped to an SSB, so the base station can identify the RACH resource that transmits the information, and thereby identify information about a beam (or SSB index) corresponding to one of the maximum RSRP values 501 and 511 of each beam set.

[0080] The UE and / or base station determine the RIS association according to the above method and can then perform a beam scanning method based on the presence or absence of the RIS association for a predetermined time period. The time period value can be predefined or configured via the PBCH payload or MIB. For example, if the UE is not associated with a RIS, scanning can be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is associated with a RIS, scanning can be performed only for the reflection mode of the RIS or only for the beam sets corresponding to the reflection mode.

[0081] The following describes a method for determining RIS association when the UE is in a connected mode with a base station.

[0082] According to an embodiment of the present disclosure, a base station can separate the RS set associated with the beam transmitted directly from the base station (hereinafter referred to as Beam Set 1) and the RS set associated with the reflection pattern of the RIS (or the beam corresponding to the reflection pattern) (hereinafter referred to as Beam Set 2) to configure Beam Set 1 and Beam Set 2 for the UE. Here, the RS included in Beam Set 1 and Beam Set 2 can be configured with only SSBs, only CSI-RS, or a combination of SSBs and CSI-RS. Alternatively, a newly defined reference signal can be used to determine the RIS association.

[0083] In the example, in the case where the RSs included in beam set 1 and beam set 2 are configured by only SSB, the base station can perform the same Figure 3 and Figure 4 The described method configures beam set 1 and beam set 2 for the UE.

[0084] In this example, when the RSs included in beam set 1 and beam set 2 are configured only by CSI-RS or by a combination of SSB and CSI-RS, the base station can semi-persistently configure beam set 1 and beam set 2 through RRC signaling. Alternatively, the base station can semi-persistently configure multiple beam sets for the UE through RRC signaling, and then dynamically indicate the beam set corresponding to beam set 1 (or beam set 2) among the configured beam sets through DCI.

[0085] According to an embodiment of the present disclosure, a base station may determine whether a UE is in RIS association based on an RS measurement value of the UE in connected mode.

[0086] In this example, the UE can measure the RS for beam set 1 to obtain the maximum RSRP value. Furthermore, the UE can measure the RS for beam set 2 to obtain the maximum RSRP value. The UE can report the two maximum RSRP values corresponding to beam set 1 and beam set 2, respectively, to the base station. In this case, the UE can report these two maximum RSRP values to the base station via the PUCCH, PUSCH, or MAC CE. The base station can determine whether the UE is in a RIS association based on the two maximum RSRP values received from the UE. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the base station can determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the base station can calculate the difference between the two maximum RSRP values. Thereafter, if this difference is greater than (or greater than or equal to) a specific threshold for determining RIS association, the base station can determine that the UE is in a RIS association. This threshold can be a predefined fixed value that can vary depending on the time when the RIS association is determined.

[0087] In this example, the UE may measure the RS for beam set 1 to obtain an RSRP value exceeding a first threshold. Furthermore, the UE may measure the RS for beam set 2 to obtain an RSRP value exceeding a second threshold. The first and second thresholds may be equal or different. Furthermore, the first and second thresholds may be pre-configured for the UE via RRC signaling. The UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 and the RSRP value exceeding the second threshold for beam set 2. In this case, the UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 and the RSRP value exceeding the second threshold for beam set 2 via the PUCCH, PUSCH, or MAC CE. The base station may differentiate the RSRP values received from the UE for each beam set and then derive the two maximum RSRP values for beam set 1 and beam set 2, respectively. The base station may determine whether the UE is in a RIS association based on the two derived maximum RSRP values. For example, if the maximum RSRP value for beam set 1 is greater than (or greater than or equal to) the maximum RSRP value for beam set 2, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the base station may calculate the difference between the two maximum RSRP values. Thereafter, if the difference is greater than (or greater than or equal to) a third threshold for determining RIS association, the base station may determine that the UE is in RIS association. The third threshold may be a predefined fixed value and may vary depending on the time point at which RIS association is determined.

[0088] According to an embodiment of the present disclosure, a UE in connected mode may determine a RIS association based on RS measurement values.

[0089] First, the base station may configure, for the UE, through RRC signaling, information regarding the time point and time period for the UE to perform an operation to determine the RIS association. For example, the RRC message sent to the UE may include information regarding the time offset and / or time period for determining the RIS association. Here, the time offset and / or time period may be indicated by a system frame number, a time slot, and / or an OFDM symbol.

[0090] The UE can measure the RS of beam set 1 to obtain the maximum RSRP value. In addition, the UE can measure the RS of beam set 2 to obtain the maximum RSRP value.

[0091] The UE can determine RIS association based on the two derived maximum RSRP values. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the UE can determine that the UE is not in RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the UE can calculate the difference between the two maximum RSRP values. Thereafter, if this difference is greater than (or greater than or equal to) a specific threshold used to determine RIS association, the UE can determine that the UE is in RIS association. This threshold can be a predefined fixed value, can vary depending on the time point of RIS association determination, or can be preconfigured by the base station through RRC signaling.

[0092] Thereafter, the UE may report to the base station whether the UE is in RIS association.

[0093] For example, the UE may transmit uplink control information (UCI) including at least one of a maximum RSRP value corresponding to beam set 1, a maximum RSRP value corresponding to beam set 2, and information indicating whether the UE is in RIS association to the base station through a physical uplink control channel (PUCCH).

[0094] As another example, the UE may transmit at least one of a maximum RSRP value corresponding to beam set 1, a maximum RSRP value corresponding to beam set 2, and information indicating whether the UE is in RIS association to the base station through a PUSCH or a MAC CE.

[0095] The UE and / or base station determine the RIS association according to the above method and can then perform a beam scanning method based on the presence or absence of the RIS association for a predetermined time period. The time period value can be predefined or configured via RRC signaling. For example, if the UE is not in a RIS association, scanning can be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is in a RIS association, scanning can be performed only for the reflection mode of the RIS or only for the beam sets corresponding to the reflection mode.

[0096] The following describes a method for (re)determining RIS association when a UE in connected mode moves.

[0097] In an example, when beam failure, radio link failure (RLF), or handover failure (HOF) occurs due to movement of the UE in connected mode, the same method as the method of determining RIS association at the time of initial access described above may be applied.

[0098] In an example, the base station may configure a time period value for determining RIS association for the UE via RRC signaling, and the UE may periodically determine whether the UE is in RIS association based on the configured time period value. In this case, the same method as the method for determining RIS association for a UE in connected mode described above may be applied. Alternatively, the base station may periodically determine whether the UE is in RIS association based on a predetermined time period. In this case, the same method as the method for determining RIS association for a UE in connected mode described above may be applied.

[0099] In an example, the base station may indicate the search space and / or beam set to the UE via DCI at a random time point to trigger the determination of the RIS association.

[0100] Figure 6 A timing diagram shows a method in which a base station determines a RIS association based on a synchronization signal measurement value when a terminal initially accesses according to an embodiment of the present disclosure.

[0101] In operation S600, the base station may transmit a PBCH payload or MIB containing configuration information on a synchronization signal set for determining an RIS association to the UE.

[0102] In the example, by referring to Figure 3 and Figure 4 According to the method described in the present invention, the base station can configure, for the UE, an SSB set associated with a beam transmitted directly from the base station (hereinafter referred to as beam set 1) and an SSB set associated with the reflection pattern of the RIS (or a beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2).

[0103] In operation S605, the UE may report a maximum RSRP value obtained from each beam set or an RSRP value exceeding a specific threshold in each beam set to the base station.

[0104] In this example, the UE can measure the SSB of beam set 1 to derive the maximum reference signal received power (RSRP) value. Additionally, the UE can measure the SSB of beam set 2 to derive the maximum RSRP value. The UE can report the two maximum RSRP values corresponding to beam set 1 and beam set 2, respectively, to the base station. In this case, the UE can report these two maximum RSRP values to the base station via the physical uplink shared channel (PUSCH) of message 3 (Msg 3) during the random access procedure.

[0105] In this example, the UE may measure the SSB of beam set 1 to obtain an RSRP value exceeding a first threshold. In addition, the UE may measure the SSB of beam set 2 to obtain an RSRP value exceeding a second threshold. The first threshold and the second threshold may be equal or different. In addition, the first threshold and the second threshold may be pre-configured for the UE via a PBCH payload, MIB, or SIB1. For example, the first threshold and the second threshold may be included in the PBCH payload or MIB of the above-mentioned operation S600. The UE may report to the base station the RSRP value exceeding the first threshold corresponding to beam set 1 and the RSRP value exceeding the second threshold corresponding to beam set 2. In this case, the UE may report to the base station the RSRP value exceeding the first threshold corresponding to beam set 1 and the RSRP value exceeding the second threshold corresponding to beam set 2 via a PUSCH of Msg 3 in the random access procedure.

[0106] In operation S610, the base station may determine whether the UE is in RIS association based on information reported by the UE.

[0107] In this example, the base station may determine whether the UE is in a RIS association based on the respective maximum RSRP values for beam set 1 and beam set 2 received from the UE in operation S605. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the base station may calculate the difference between the two maximum RSRP values. Thereafter, if the difference is greater than (or greater than or equal to) a specific threshold for determining RIS association, the base station may determine that the UE is in a RIS association. The threshold may be a predefined fixed value and may vary depending on the time point when the RIS association is determined.

[0108] In an example, the base station may differentiate the RSRP values received from the UE in operation S605 (the RSRP value exceeding a first threshold for beam set 1 and the RSRP value exceeding a second threshold for beam set 2) for each beam set, and then derive two maximum RSRP values for beam set 1 and beam set 2, respectively. The base station may determine whether the UE is in a RIS association based on the two derived maximum RSRP values. For example, if the maximum RSRP value for beam set 1 is greater than (or greater than or equal to) the maximum RSRP value for beam set 2, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value for beam set 2 is greater than (or greater than or equal to) the maximum RSRP value for beam set 1, the base station may calculate the difference between the two maximum RSRP values. Thereafter, if this difference is greater than (or greater than or equal to) a third threshold for determining RIS association, the base station may determine that the UE is in a RIS association. The third threshold may be a predefined fixed value that may vary depending on the time at which the RIS association is determined.

[0109] In operation S615, the base station may determine the UE's RIS association according to operation S610 and then perform a beam scanning method based on the presence or absence of the RIS association for a predetermined time period. Here, the time period value may be predefined or configured via the PBCH payload or MIB. For example, if the UE is not associated with a RIS, scanning may be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is associated with a RIS, scanning may be performed only for the reflection mode of the RIS or only for the beam sets corresponding to the reflection mode.

[0110] Figure 7 A timing diagram illustrating a method in which a terminal determines a RIS association based on a synchronization signal measurement value during initial access according to an embodiment of the present disclosure is shown.

[0111] In operation S700 , the base station may transmit a PBCH payload or MIB containing configuration information on a synchronization signal set for determining RIS association and a specific threshold for determining RIS association to the UE.

[0112] In the example, by referring to Figure 3 and Figure 4 In the method described, the base station can configure, for the UE, a set of SSBs associated with a beam transmitted directly from the base station (hereinafter referred to as beam set 1) and a set associated with a reflection pattern of a RIS (or a beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2), as well as a specific threshold for determining RIS association.

[0113] In operation S705 , the UE may determine whether the UE is in RIS association based on the measurement value of the synchronization signal.

[0114] In this example, the UE may measure the SSB of beam set 1 to obtain the maximum RSRP value. Furthermore, the UE may measure the SSB of beam set 2 to obtain the maximum RSRP value. The UE may determine that it is in a RIS association based on the two obtained maximum RSRP values. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the UE may determine that it is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the UE may calculate the difference between the two maximum RSRP values. Thereafter, if the difference is greater than (or greater than or equal to) a specific threshold configured in operation S700, the UE may determine that it is in a RIS association.

[0115] In operation S710 , the UE may report to the base station whether the UE is in RIS association.

[0116] In an example, the UE may transmit at least one of a maximum RSRP value corresponding to beam set 1, a maximum RSRP value corresponding to beam set 2, and information indicating whether the UE is in RIS association to the base station through the PUSCH of Msg 3 in the random access procedure.

[0117] In an example, the UE may transmit information indicating whether the UE is in a RIS association to the base station via a RACH resource. Here, the RACH resource may be mapped to an SSB, so the base station can identify the RACH resource on which the information is transmitted, and thereby identify information about a beam (or SSB index) corresponding to one of the maximum RSRP values of each beam set.

[0118] In operation S715, the UE may determine its RIS association according to operation S710 and then, for a predetermined time period, perform a beam scanning method based on the presence or absence of a RIS association. Here, the time period value may be predefined or configured via the PBCH payload or MIB. For example, if the UE is not associated with a RIS, scanning may be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is associated with a RIS, scanning may be performed only for the reflection mode of the RIS or only for the beam sets corresponding to the reflection mode.

[0119] Figure 8 A timing diagram illustrating a method in which a base station determines a RIS association based on an RS measurement value of a UE in a connected mode according to an embodiment of the present disclosure is shown.

[0120] In operation S800, the base station may configure an RS set associated with the RIS through RRC signaling and / or DCI.

[0121] For example, the base station can separate the RS set associated with the beam transmitted directly from the base station (hereinafter referred to as beam set 1) and the RS set associated with the reflection pattern of the RIS (or the beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2) to configure beam set 1 and beam set 2 for the UE. Here, the RS included in beam set 1 and beam set 2 can be configured with only SSB, only CSI-RS, or a combination of SSB and CSI-RS. Alternatively, a newly defined reference signal can be used to determine the RIS association.

[0122] In the example, in the case where the RSs included in beam set 1 and beam set 2 are configured only by SSB, the base station can Figure 3 and Figure 4 A similar method is described to configure beam set 1 and beam set 2 for the UE.

[0123] In this example, when the RSs included in beam set 1 and beam set 2 are configured only by CSI-RS or by a combination of SSB and CSI-RS, the base station can semi-persistently configure beam set 1 and beam set 2 through RRC signaling. Alternatively, the base station can semi-persistently configure multiple beam sets for the UE through RRC signaling, and then dynamically indicate the beam set corresponding to beam set 1 (or beam set 2) among the configured beam sets through DCI.

[0124] In operation S805, the UE may report a maximum RSRP value obtained from each beam set or an RSRP value exceeding a specific threshold in each beam set to the base station.

[0125] In this example, the UE can measure the RS of beam set 1 to obtain the maximum RSRP value. In addition, the UE can measure the RS of beam set 2 to obtain the maximum RSRP value. The UE can report the two maximum RSRP values corresponding to beam set 1 and beam set 2 to the base station. In this case, the UE can report the two maximum RSRP values to the base station via PUCCH, PUSCH, or MAC CE.

[0126] In this example, the UE may measure the RS of beam set 1 to obtain an RSRP value exceeding a first threshold. Furthermore, the UE may measure the RS of beam set 2 to obtain an RSRP value exceeding a second threshold. The first threshold and the second threshold may be equal or different. Furthermore, the first threshold and the second threshold may be pre-configured for the UE via RRC signaling in operation S800. The UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 and the RSRP value exceeding the second threshold for beam set 2. In this case, the UE may report to the base station the RSRP value exceeding the first threshold for beam set 1 and the RSRP value exceeding the second threshold for beam set 2 via PUCCH, PUSCH, or MAC CE.

[0127] In operation S810, the base station may determine whether the UE is in RIS association based on information reported by the UE.

[0128] In an example, a base station may determine whether a UE is in a RIS association based on the two maximum RSRP values received from the UE. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the base station may calculate the difference between the two maximum RSRP values. Thereafter, if this difference is greater than (or greater than or equal to) a specific threshold for determining RIS association, the base station may determine that the UE is in a RIS association. This threshold may be a predefined fixed value and may vary depending on the time at which the RIS association is determined.

[0129] In an example, the base station may differentiate the RSRP values received from the UE for each beam set and then derive the two maximum RSRP values corresponding to beam set 1 and beam set 2, respectively. The base station may determine whether the UE is in a RIS association based on the two derived maximum RSRP values. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the base station may determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the base station may calculate the difference between the two maximum RSRP values. Thereafter, if this difference is greater than (or greater than or equal to) a third threshold for determining RIS association, the base station may determine that the UE is in a RIS association. The third threshold may be a predefined fixed value that may vary depending on the time at which the RIS association is determined.

[0130] In operation S815, the base station may determine the RIS association of the UE according to operation S810 and then perform a beam scanning method based on the presence or absence of the RIS association for a predetermined time period. The time period may be predefined or configured via RRC signaling in operation S800. For example, if the UE is not associated with a RIS, scanning may be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is associated with a RIS, scanning may be performed only for the reflection mode of the RIS or only for beam sets corresponding to the reflection mode.

[0131] Figure 9 A timing diagram illustrating a method in which a terminal in a connected mode determines a RIS association based on an RS measurement value according to an embodiment of the present disclosure is shown.

[0132] In operation S900 , the base station may configure an RS set associated with the RIS through RRC signaling and / or DCI.

[0133] For example, the base station can separate the RS set associated with the beam transmitted directly from the base station (hereinafter referred to as beam set 1) and the RS set associated with the reflection pattern of the RIS (or the beam corresponding to the reflection pattern) (hereinafter referred to as beam set 2) to configure beam set 1 and beam set 2 for the UE. Here, the RS included in beam set 1 and beam set 2 can be configured with only SSB, only CSI-RS, or a combination of SSB and CSI-RS. Alternatively, a newly defined reference signal can be used to determine the RIS association.

[0134] In the example, in the case where the RSs included in beam set 1 and beam set 2 are configured only by SSB, the base station can Figure 3 and Figure 4 A similar method is described to configure beam set 1 and beam set 2 for the UE.

[0135] In this example, when the RSs included in beam set 1 and beam set 2 are configured only by CSI-RS or by a combination of SSB and CSI-RS, the base station can semi-persistently configure beam set 1 and beam set 2 through RRC signaling. Alternatively, the base station can semi-persistently configure multiple beam sets for the UE through RRC signaling, and then dynamically indicate the beam set corresponding to beam set 1 (or beam set 2) among the configured beam sets through DCI.

[0136] In addition, the base station may configure a specific threshold for determining RIS association through RRC signaling in operation S900.

[0137] In addition, the base station may configure information about the time point and time period for the UE to perform the operation of determining the RIS association through RRC signaling in operation S900. For example, the RRC message sent to the UE may include information about the time offset and / or time period for determining the RIS association. Here, the time offset and / or time period may be indicated by a system frame number, a time slot, and / or an OFDM symbol.

[0138] In operation S905 , the UE may determine whether the UE is in RIS association based on the RS measurement value.

[0139] In this example, the UE may measure the RS of beam set 1 to obtain the maximum RSRP value. Furthermore, the UE may measure the RS of beam set 2 to obtain the maximum RSRP value. Based on the two obtained maximum RSRP values, the UE may determine whether the UE is in a RIS association. For example, if the maximum RSRP value corresponding to beam set 1 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 2, the UE may determine that the UE is not in a RIS association. For example, if the maximum RSRP value corresponding to beam set 2 is greater than (or greater than or equal to) the maximum RSRP value corresponding to beam set 1, the UE may calculate the difference between the two maximum RSRP values. Thereafter, if the difference is greater than (or greater than or equal to) a specific threshold configured in operation S900, the UE may determine that the UE is in a RIS association. Alternatively, the threshold may be a predefined fixed value or may vary depending on the time at which the RIS association is determined.

[0140] In operation S910 , the UE may report to the base station whether the UE is in RIS association.

[0141] In an example, the UE may transmit UCI including at least one of a maximum RSRP value corresponding to beam set 1, a maximum RSRP value corresponding to beam set 2, and information indicating whether the UE is in RIS association to the base station through the PUCCH.

[0142] In an example, the UE may transmit at least one of a maximum RSRP value corresponding to beam set 1, a maximum RSRP value corresponding to beam set 2, and information indicating whether the UE is in RIS association to the base station through a PUSCH or a MAC CE.

[0143] In operation S915, the UE may determine its RIS association according to operation S910 and then perform a beam scanning method based on the presence or absence of a RIS association for a predetermined time period. The time period may be predefined or configured via RRC signaling in operation S900. For example, if the UE is not associated with a RIS, scanning may be performed only for beam sets directly transmitted from the base station. Alternatively, if the UE is associated with a RIS, scanning may be performed only for the reflection mode of the RIS or only for beam sets corresponding to the reflection mode.

[0144] Figure 10 The structure of a UE according to an embodiment of the present disclosure is shown.

[0145] refer to Figure 10 , the UE may include a transceiver 1010, a controller 1020, and a memory 1030. In the present disclosure, the controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

[0146] The transceiver 1010 may transmit / receive signals with other network entities. For example, the transceiver 1010 may receive system information, control information, synchronization signals, or reference signals from a base station.

[0147] The controller 1020 may control the overall operation of the UE according to the embodiments of the present disclosure. For example, the controller 1020 may control the signal flow between the various modules to perform the operations according to the above-described flowchart. Specifically, the controller 1020 may control the transceiver to receive information about the first beam set and the second beam set and information about the first threshold from the base station. The controller 1020 may also control the transceiver to determine whether the UE is associated with a reconfigurable smart surface (RIS) based on the first threshold and measurement results of the first beam set and the second beam set, and transmit information indicating whether the UE is associated with the RIS to the base station. Depending on whether the UE is associated with the RIS, beam scanning is performed based on one of the first beam set and the second beam set.

[0148] The memory 1030 may store at least one of information transmitted / received by the transceiver 1010 and information generated by the controller 1020 .

[0149] Figure 11 The structure of a base station according to an embodiment of the present disclosure is shown.

[0150] refer to Figure 11 , the base station may include a transceiver 1110, a controller 1120, and a memory 1130. In the present disclosure, the controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

[0151] The transceiver 1110 may transmit / receive signals with other network entities. For example, the transceiver 1110 may transmit system information, control information, data, synchronization signals, or reference signals to the UE.

[0152] The controller 1120 can control the overall operation of the base station according to the embodiments of the present disclosure. For example, the controller 1120 can control the signal flow between various modules to perform the operations according to the above-described flowchart. Specifically, the controller 1120 can control the transceiver to transmit information about the first beam set and the second beam set, can control the transceiver to receive measurement results of the first beam set and the second beam set from the UE, and can determine whether the UE is in a RIS association based on the measurement results and a predetermined threshold. Depending on whether the UE is in the RIS association, beam scanning is performed based on one of the first beam set and the second beam set.

[0153] In addition, the memory 1130 may store at least one of information transmitted / received by the transceiver 1110 and information generated by the controller 1120 .

[0154] In the method of the present disclosure, part or all of the content of each embodiment may be combined and implemented without departing from the essential spirit and scope of the present disclosure.

[0155] The embodiments of the present disclosure described and illustrated in the specification and drawings are merely specific examples provided to facilitate explanation of the technical content of the present disclosure and to aid understanding, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other variations can be implemented based on the technical ideas of the present disclosure.

[0156] In addition, although specific terms are used in the specification and drawings to describe and illustrate exemplary embodiments of the present disclosure, these terms are used only in a general sense and are intended only to facilitate explanation of the technical content of the present disclosure and to aid understanding, and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that in addition to the embodiments described herein, other variations may be implemented based on the technical ideas of the present disclosure.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, information about the first beam set and the second beam set and information about a first threshold; Determining whether the terminal is in a reconfigurable smart surface (RIS) association based on measurement results for the first beam set and the second beam set and the first threshold; as well as sending information indicating whether the terminal is in the RIS association to the base station, The beam scanning is performed based on one of the first beam set and the second beam set according to whether the terminal is in the RIS association.

2. The method according to claim 1, wherein The first beam set includes at least one synchronization signal block (SSB) or at least one channel state information reference signal (CSI-RS) associated with a beam transmitted by the base station, and the second beam set includes at least one SSB or at least one CSI-RS associated with a reflection pattern of a RIS. The information about the first beam set and the second beam set is received through a physical broadcast channel PBCH payload, a master information block MIB, or a radio resource control RRC signaling.

3. The method according to claim 1, wherein Determining whether the terminal is in RIS association includes: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; identifying a difference between the first RSRP value and the second RSRP value if the first RSRP value is less than or equal to the second RSRP value; and In a case where the difference between the first RSRP value and the second RSRP value is greater than or equal to the first threshold, it is determined that the terminal is in the RIS association.

4. The method according to claim 1, wherein Determining whether the terminal is in the RIS association includes: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; and When the first RSRP value is greater than or equal to the second RSRP value, it is determined that the terminal is not in the RIS association.

5. A method performed by a base station in a wireless communication system, the method comprising: sending information about the first beam set and the second beam set to the terminal; receiving, from the terminal, measurement results for the first beam set and the second beam set; as well as Based on the measurement result and a predetermined threshold, determining whether the terminal is in a reconfigurable smart surface (RIS) association; The beam scanning is performed based on one of the first beam set and the second beam set according to whether the terminal is in the RIS association.

6. The method according to claim 5, wherein: The first beam set includes at least one synchronization signal block (SSB) or at least one channel state information reference signal (CSI-RS) associated with a beam transmitted by the base station, and the second beam set includes at least one SSB or at least one CSI-RS associated with a reflection pattern of a RIS. The information about the first beam set and the second beam set is sent through a physical broadcast channel PBCH payload, a master information block MIB, or a radio resource control RRC signaling.

7. The method according to claim 5, wherein: Determining whether the terminal is in the RIS association includes: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; identifying a difference between the first RSRP value and the second RSRP value if the first RSRP value is less than or equal to the second RSRP value; and In a case where the difference between the first RSRP value and the second RSRP value is greater than or equal to the predetermined threshold, it is determined that the terminal is in the RIS association.

8. The method according to claim 5, wherein Determining whether the terminal is in the RIS association includes: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; and When the first RSRP value is greater than or equal to the second RSRP value, it is determined that the terminal is not in the RIS association.

9. A terminal in a wireless communication system, the terminal comprising: transceiver; as well as controller, Wherein, the controller is configured as follows: controlling the transceiver to receive information about the first beam set and the second beam set and information about the first threshold from the base station; Determining whether the terminal is in a reconfigurable smart surface (RIS) association based on measurement results for the first beam set and the second beam set and the first threshold; and controlling the transceiver to send information indicating whether the terminal is in the RIS association to the base station, and The beam scanning is performed based on one of the first beam set and the second beam set according to whether the terminal is in the RIS association.

10. The terminal according to claim 9, wherein: The first beam set includes at least one synchronization signal block (SSB) or at least one channel state information reference signal (CSI-RS) associated with a beam transmitted by the base station, and the second beam set includes at least one SSB or at least one CSI-RS associated with a reflection pattern of a RIS. The information about the first beam set and the second beam set is received through a physical broadcast channel PBCH payload, a master information block MIB, or a radio resource control RRC signaling. The terminal according to claim 9 , wherein: The controller is configured as follows: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; identifying a difference between the first RSRP value and the second RSRP value if the first RSRP value is less than or equal to the second RSRP value; as well as In a case where the difference between the first RSRP value and the second RSRP value is greater than or equal to the first threshold, it is determined that the terminal is in the RIS association.

12. The terminal according to claim 11, wherein The controller is configured as follows: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; as well as When the first RSRP value is greater than or equal to the second RSRP value, it is determined that the terminal is not in the RIS association.

13. A base station in a wireless communication system, the base station comprising: transceiver; as well as controller, Wherein, the controller is configured as follows: controlling the transceiver to send information about the first beam set and the second beam set to the terminal; controlling the transceiver to receive measurement results for the first beam set and the second beam set from the terminal; and Based on the measurement result and a predetermined threshold, determining whether the terminal is in a reconfigurable smart surface (RIS) association; and The beam scanning is performed based on one of the first beam set and the second beam set according to whether the terminal is in the RIS association.

14. The base station according to claim 13, wherein: The first beam set includes at least one synchronization signal block (SSB) or at least one channel state information reference signal (CSI-RS) associated with a beam transmitted by the base station, and the second beam set includes at least one SSB or at least one CSI-RS associated with a reflection pattern of a RIS. The information about the first beam set and the second beam set is sent through a physical broadcast channel PBCH payload, a master information block MIB, or a radio resource control RRC signaling.

15. The base station according to claim 13, wherein: The controller is configured as follows: identifying a first RSRP value corresponding to the first beam set and a second RSRP value corresponding to the second beam set; When the first RSRP value is greater than or equal to the second RSRP value, determining that the terminal is not in the RIS association; identifying a difference between the first RSRP value and the second RSRP value if the first RSRP value is less than or equal to the second RSRP value; as well as In a case where the difference between the first RSRP value and the second RSRP value is greater than or equal to the predetermined threshold, it is determined that the terminal is in the RIS association.

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