Method and apparatus for recovering beam failure

Abstract

A method of a terminal comprises the steps of: receiving beams from a base station; receiving system information including indication information indicating a correspondence relationship between each of the beams and a type of an electromagnetic field; obtaining first information used to determine the type of the electromagnetic field to which the terminal belongs on the basis of the system information; detecting a beam failure after obtaining the first information; determining the type of the electromagnetic field to which the terminal belongs on the basis of the first information in response to the beam failure; and performing a beam failure recovery procedure with the base station on the basis of the determined type of the electromagnetic field.

Description

Beam failure recovery method and device

[0001] The present disclosure relates to a beam failure recovery technique, and more particularly, to a beam failure recovery technique based on the classification of types of electromagnetic fields.

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

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

[0004] The types of areas (hereinafter referred to as "electromagnetic fields") radiated by radio waves transmitted from a base station antenna can be divided into near fields and far fields. In the far field, radio waves can be assumed to be planar waves (hereinafter referred to as "plane wave assumptions"). The boundary between the far field and the near field can be determined based on the Rayleigh distance. The Rayleigh distance can increase as the frequency of the signal used for wireless communication increases. The Rayleigh distance can increase as the maximum length of the antenna array of the terminal and / or base station increases.

[0005] In 6G communication networks, the terahertz (THz) band, which is a higher frequency band than FR2 (frequency range 2), can be utilized, and an XL-MIMO (extra-large multiple input multiple output) system can be utilized. In an XL-MIMO system, the size of the antenna array of the terminal / base station may be larger than the size of the antenna array used in the existing FR2 band. Considering the influence of the signal frequency and the size of the antenna array of the terminal / base station on the Rayleigh distance, the electromagnetic field that was previously considered the far-field may be considered the near-field in the terahertz band. The beam failure recovery technology that was previously used in the far-field may not be applicable in the terahertz band. Therefore, a beam failure recovery method in the near-field that does not assume the plane wave assumption may be required.

[0006] The purpose of the present disclosure to solve the above problems is to provide a method and device for beam failure recovery in the near field.

[0007] According to a first embodiment of the present disclosure for achieving the above object, a method of a terminal includes the steps of receiving beams from a base station, receiving system information including indication information indicating a correspondence between each of the beams and a type of electromagnetic field, obtaining first information used to determine a type of electromagnetic field to which the terminal belongs based on the system information, detecting a beam failure after obtaining the first information, determining a type of electromagnetic field to which the terminal belongs based on the first information in response to the beam failure, and performing a beam failure recovery procedure with the base station based on the determined type of electromagnetic field.

[0008] The above correspondence relationship can be established based on the correspondence relationship between each of the SSBs (synchronization signal blocks) associated with the beams and the type of electromagnetic field.

[0009] The method of the terminal may further include a step of measuring RSRP (reference signal received power) values ​​of the beams after receiving the beams, and determining candidate beams among the beams based on the RSRP values, and the step of performing the beam failure recovery procedure may include a step of determining first beams corresponding to the determined type of electromagnetic field among the candidate beams based on the indication information, a step of transmitting a beam failure recovery request to the base station in a RO (random access channel occasion) corresponding to SSBs associated with the first beams, a step of receiving a response to the beam failure recovery request from the base station, and a step of performing communication with the base station through one or more beams determined by the response among the first beams.

[0010] The system information includes a set of parameters associated with the first information, and the set of parameters may include at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information.

[0011] The first information may include at least one of information on the distance between the base station and the terminal or information on the maximum phase difference between the beams received by antennas belonging to the terminal.

[0012] The step of acquiring the first information may be performed according to a period indicated by the period parameter, and the step of determining the type of the electromagnetic field to which the terminal belongs may be performed based on a comparison result between the number of times the type of the electromagnetic field to which the terminal belongs is determined as a near-field and the number of times the type of the electromagnetic field to which the terminal belongs is determined as a far-field within a time window indicated by the time window parameter.

[0013] The step of obtaining the first information may include a step of transmitting a request for information on the distance between the base station and the terminal to the base station after receiving the system information, and a step of obtaining information on the distance between the base station and the terminal from the base station in response to the request.

[0014] The step of obtaining the first information may include a step of measuring phase differences between the beams received by the antennas belonging to the terminal after receiving the system information, and a step of determining a maximum phase difference among the phase differences to obtain information on the maximum phase difference.

[0015] The step of determining the type of electromagnetic field to which the terminal belongs may be performed based on at least one of a comparison result between the maximum phase difference indicated by the information on the maximum phase difference and a phase difference threshold or a comparison result between the distance between the base station and the terminal indicated by the information on the distance and a distance threshold.

[0016] A method of a base station according to a first embodiment of the present disclosure for achieving the above object includes the steps of transmitting beams to a terminal, establishing a correspondence between each of SSBs associated with the beams and a type of electromagnetic field, transmitting system information including indication information indicating the correspondence, and performing a beam failure recovery procedure with the terminal that detects a beam failure after transmitting the system information.

[0017] In the step of establishing the above correspondence relationship, each of the SSBs associated with the beams can be determined as either a near field SSB or a far field SSB.

[0018] The method of the base station may further include, before setting the correspondence, a step of determining an average Rayleigh distance between terminals belonging to a cell formed by the base station and the base station, and a ratio of one or more SSB(s) determined as the near-field SSB among the SSBs and one or more SSB(s) determined as the far-field SSB among the SSBs may be determined based on the average Rayleigh distance, and the average Rayleigh distance may be determined based on at least one of a maximum length of an antenna array belonging to the base station, a maximum length of an antenna array belonging to the terminals, or a frequency band used for communication between the base station and the terminals.

[0019] The method of the base station may further include a step of setting a parameter set associated with first information used to determine the type of the electromagnetic field to which the terminal belongs after setting the correspondence relationship, wherein the system information includes the parameter set.

[0020] The above parameter set may include at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information.

[0021] The method of the base station may include a step of receiving a request for information on the distance between the base station and the terminal from the terminal after transmitting the system information, a step of measuring the distance between the base station and the terminal in response to the request, and a step of transmitting distance information indicating the distance to the terminal.

[0022] The above distance may be measured based on at least one of a delay time of a PRACH (physical random access channel) preamble received from the terminal or one or more signals used to set timing advance between the terminal and the base station.

[0023] The step of performing the beam failure recovery procedure may include the steps of receiving a beam failure recovery request from the terminal that detected the beam failure in a random access channel occasion (RO) corresponding to SSBs associated with first beams corresponding to a type of electromagnetic field to which the terminal belongs as determined by the terminal, transmitting a response to the beam failure recovery request to the terminal, and performing communication with the terminal using one or more beams determined by the response.

[0024] According to a first embodiment of the present disclosure for achieving the above object, a terminal includes at least one processor, wherein the at least one processor causes the terminal to receive beams from a base station, receive system information including indication information indicating a correspondence between each of the beams and a type of electromagnetic field, obtain first information used to determine a type of electromagnetic field to which the terminal belongs based on the system information, detect a beam failure after obtaining the first information, determine a type of electromagnetic field to which the terminal belongs based on the first information in response to the beam failure, and perform a beam failure recovery procedure with the base station based on the determined type of electromagnetic field.

[0025] The system information includes a set of parameters associated with the first information, and the set of parameters may include at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information.

[0026] The first information may include at least one of information on the distance between the base station and the terminal or information on the maximum phase difference between the beams received by antennas belonging to the terminal.

[0027] According to the present disclosure, a base station can determine synchronization signal blocks (SSBs) as either near-field SSBs or far-field SSBs and establish a correspondence between SSBs and types of electromagnetic fields. The base station can set a parameter set so that the terminal can measure information used to determine the type of electromagnetic field to which the terminal belongs. The base station can transmit association information and the parameter set including the above-described correspondence to the terminal through system information. The terminal can obtain information on the distance between the terminal and the base station or information on the maximum phase difference between beams received by antennas belonging to the terminal based on a measurement operation of the terminal or a transmission from the base station. The terminal can determine the type of electromagnetic field to which the terminal belongs based on the obtained information. The terminal can transmit an RPACH preamble in a random access channel occasion (RO) corresponding to SSBs matching the determined type of electromagnetic field. The base station and the terminal can communicate based on beams matching the type of electromagnetic field to which the terminal belongs. Through the above-described procedure, the base station and terminal can perform a beam failure recovery procedure even if the electromagnetic field previously considered as a long-range field is considered as a short-range field.

[0028] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0029] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0030] Figure 3 is a block diagram illustrating a first embodiment of communication nodes performing communication.

[0031] Figure 4a is a block diagram illustrating a first embodiment of a transmission path.

[0032] Figure 4b is a block diagram illustrating a first embodiment of a receiving path.

[0033] Figure 5 is a conceptual diagram illustrating a first embodiment of a system frame in a communication system.

[0034] Figure 6 is a conceptual diagram illustrating a first embodiment of a subframe in a communication system.

[0035] Figure 7 is a conceptual diagram illustrating a first embodiment of a slot in a communication system.

[0036] Figure 8 is a conceptual diagram illustrating a first embodiment of time-frequency resources in a communication system.

[0037] Figure 9 is a conceptual diagram illustrating an embodiment of a method for distinguishing types of electromagnetic fields.

[0038] Figure 10 is a flowchart illustrating an embodiment of a beam failure recovery procedure.

[0039] Fig. 11 is a conceptual diagram illustrating an embodiment of a method for corresponding between a random access channel occasion (RO) and a synchronization signal block (SSB) on a resource grid.

[0040] FIG. 12a is a flowchart illustrating a first embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0041] FIG. 12b is a flowchart illustrating a first embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0042] FIG. 13a is a flowchart illustrating a second embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0043] FIG. 13b is a flowchart illustrating a second embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0044] This disclosure may be subject to various modifications and various embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the disclosure.

[0045] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" may refer to a combination of multiple related items described herein or to any of multiple related items described herein.

[0046] In the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Additionally, in the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.”

[0047] In the present disclosure, (re)transmission may mean “transmission,” “retransmission,” or “transmission and retransmission,” (re)setting may mean “setting,” “resetting,” or “setting and resetting,” (re)connection may mean “connection,” “reconnection,” or “connection and reconnection,” and (re)connection may mean “connection,” “reconnection,” or “connection and reconnection.”

[0048] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0049] The terminology used in this disclosure is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0050] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0051] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding in describing the present disclosure, the same reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted. In addition to the embodiments explicitly described in the present disclosure, operations may be performed according to combinations of embodiments, extensions of embodiments, and / or modifications of embodiments. The performance of some operations may be omitted, and the order of operation may be changed.

[0052] In an embodiment, even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, if an operation of a UE (user equipment) is described, a corresponding base station can perform an operation corresponding to the operation of the UE. Conversely, if an operation of a base station is described, a corresponding UE can perform an operation corresponding to the operation of the base station.

[0053] A base station may be referred to as a NodeB, an evolved NodeB, a gNodeB (next generation node B), a gNB, a device, an apparatus, a node, a communication node, a BTS (base transceiver station), a RRH (radio remote head), a TRP (transmission reception point), a RU (radio unit), an RSU (road side unit), a radio transceiver, an access point, an access node, etc. A UE may be referred to as a terminal, a device, an apparatus, a node, a communication node, an end node, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, an OBU (on-broad unit), etc.

[0054] In the present disclosure, signaling may be at least one of upper layer signaling, MAC signaling, or PHY (physical) signaling. A message used for upper layer signaling may be referred to as an "upper layer message" or an "upper layer signaling message." A message used for MAC signaling may be referred to as a "MAC message" or a "MAC signaling message." A message used for PHY signaling may be referred to as a "PHY message" or a "PHY signaling message." Upper layer signaling may refer to a transmission and reception operation of system information (e.g., a master information block (MIB), a system information block (SIB)) and / or an RRC message. MAC signaling may refer to a transmission and reception operation of a MAC control element (CE). PHY signaling may refer to a transmission and reception operation of control information (e.g., downlink control information (DCI), uplink control information (UCI), sidelink control information (SCI)).

[0055] In the present disclosure, “an operation (e.g., a transmission operation) is set” may mean that “setting information for the operation (e.g., an information element, a parameter)” and / or “information instructing the performance of the operation” is signaled. “An information element (e.g., a parameter) is set” may mean that the information element is signaled. In the present disclosure, “a signal and / or a channel” may mean a signal, a channel, or “a signal and a channel,” and a signal may be used to mean “a signal and / or a channel.”

[0056] The communication network to which the embodiment is applied is not limited to what is described below, and the embodiment may be applied to various communication networks (e.g., 4G communication networks, 5G communication networks, and / or 6G communication networks). Here, the communication network may be used in the same sense as the communication system.

[0057] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0058] Referring to FIG. 1, the communication system (100) may include a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system (100) may further include a core network (e.g., a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), a mobility management entity (MME)). If the communication system (100) is a 5G communication system (e.g., a new radio (NR) system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc.

[0059] A plurality of communication nodes (110 to 130) can support a communication protocol (e.g., LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.) specified in the 3GPP (3rd generation partnership project) standard. The plurality of communication nodes (110 to 130) may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (non-orthogonal multiple access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (space division multiple access) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0060] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0061] Referring to FIG. 2, a communication node (200) may include at least one processor (210), a memory (220), and a transmission / reception device (230) that is connected to a network and performs communication. In addition, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) and communicate with each other.

[0062] The processor (210) can execute program commands stored in at least one of the memory (220) and the storage device (260). The processor (210) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which the methods according to embodiments of the present disclosure are performed. Each of the memory (220) and the storage device (260) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0063] Referring again to FIG. 1, the communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) may form a macro cell. Each of the fourth base station (120-1) and the fifth base station (120-2) may form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) may be within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be within the cell coverage of the third base station (110-3). The first terminal (130-1) may be within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be within the cell coverage of the fifth base station (120-2).

[0064] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as a NodeB (NB), an evolved NodeB (eNB), a gNB, an advanced base station (ABS), a high reliability-base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multihop relay-base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability-relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), etc.

[0065] Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability-mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, on board unit (OBU), etc.

[0066] Meanwhile, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to the core network via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0067] Additionally, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may support MIMO transmission (e.g., single user (SU)-MIMO, multi user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, sidelink communication (e.g., device to device communication (D2D), proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO scheme, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) by the SU-MIMO scheme. Alternatively, the second base station (110-2) can transmit signals to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive signals from the second base station (110-2) based on the MU-MIMO method.

[0068] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP scheme, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) based on the CoMP scheme. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive a signal with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage based on the CA scheme. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control sidelink communication between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform sidelink communication under the control of the second base station (110-2) and the third base station (110-3), respectively.

[0069] Meanwhile, communication nodes performing communication in a communication network may be configured as follows. The communication node illustrated in Fig. 3 may be a specific embodiment of the communication node illustrated in Fig. 2.

[0070] Figure 3 is a block diagram illustrating a first embodiment of communication nodes performing communication.

[0071] Referring to FIG. 3, each of the first communication node (300a) and the second communication node (300b) may be a base station or a UE. The first communication node (300a) may transmit a signal to the second communication node (300b). The transmission processor (311) included in the first communication node (300a) may receive data (e.g., a data unit) from a data source (310). The transmission processor (311) may receive control information from the controller (316). The control information may include at least one of system information, RRC configuration information (e.g., information configured by RRC signaling), MAC control information (e.g., MAC CE), or PHY control information (e.g., DCI, SCI).

[0072] The transmitting processor (311) may perform a processing operation on data (e.g., an encoding operation, a symbol mapping operation, etc.) to generate data symbol(s). The transmitting processor (311) may perform a processing operation on control information (e.g., an encoding operation, a symbol mapping operation, etc.) to generate control symbol(s). In addition, the transmitting processor (311) may generate synchronization / reference symbol(s) for a synchronization signal and / or a reference signal.

[0073] The Tx MIMO processor (312) may perform a spatial processing operation (e.g., a precoding operation) on data symbol(s), control symbol(s), and / or synchronization / reference symbol(s). The output (e.g., a symbol stream) of the Tx MIMO processor (312) may be provided to modulators (MODs) included in the transceivers (313a to 313t). The modulators (MODs) may perform a processing operation on the symbol stream to generate modulation symbols, and may perform an additional processing operation (e.g., an analog conversion operation, an amplification operation, a filtering operation, an upconversion operation) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (313a to 313t) may be transmitted via the antennas (314a to 314t).

[0074] Signals transmitted by the first communication node (300a) may be received by antennas (364a to 364r) of the second communication node (300b). Signals received by the antennas (364a to 364r) may be provided to demodulators (DEMODs) included in transceivers (363a to 363r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (362) may perform a MIMO detection operation on the symbols. The receiving processor (361) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (361) may be provided to a data sink (360) and a controller (366). For example, data may be provided to the data sink (360), and control information may be provided to the controller (366).

[0075] Meanwhile, the second communication node (300b) can transmit a signal to the first communication node (300a). The transmitting processor (368) included in the second communication node (300b) can receive data (e.g., data units) from a data source (367) and perform a processing operation on the data to generate data symbol(s). The transmitting processor (368) can receive control information from the controller (366) and perform a processing operation on the control information to generate control symbol(s). In addition, the transmitting processor (368) can perform a processing operation on a reference signal to generate reference symbol(s).

[0076] The Tx MIMO processor (369) may perform spatial processing operations (e.g., precoding operations) on data symbol(s), control symbol(s), and / or reference symbol(s). The output (e.g., symbol stream) of the Tx MIMO processor (369) may be provided to modulators (MODs) included in the transceivers (363a to 363t). The modulators (MODs) may perform processing operations on the symbol streams to generate modulation symbols, and may perform additional processing operations (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations) on the modulation symbols to generate signals. The signals generated by the modulators (MODs) of the transceivers (363a to 363t) may be transmitted via the antennas (364a to 364t).

[0077] Signals transmitted by the second communication node (300b) may be received by the antennas (314a to 314r) of the first communication node (300a). The signals received by the antennas (314a to 314r) may be provided to demodulators (DEMODs) included in the transceivers (313a to 313r). The demodulator (DEMOD) may perform a processing operation (e.g., a filtering operation, an amplification operation, a downconversion operation, a digital conversion operation) on the signal to obtain samples. The demodulator (DEMOD) may perform an additional processing operation on the samples to obtain symbols. The MIMO detector (320) may perform a MIMO detection operation on the symbols. The receiving processor (319) may perform a processing operation (e.g., a deinterleaving operation, a decoding operation) on the symbols. The output of the receiving processor (319) may be provided to a data sink (318) and a controller (316). For example, data may be provided to the data sink (318) and control information may be provided to the controller (316).

[0078] Memories (315 and 365) can store data, control information, and / or program code. Scheduler (317) can perform scheduling operations for communication. The processors (311, 312, 319, 361, 368, 369) and controllers (316, 366) illustrated in FIG. 3 may be the processor (210) illustrated in FIG. 2 and may be used to perform the methods described in the present disclosure.

[0079] FIG. 4a is a block diagram illustrating a first embodiment of a transmission path, and FIG. 4b is a block diagram illustrating a first embodiment of a reception path.

[0080] Referring to FIGS. 4A and 4B, a transmission path (410) may be implemented in a communication node that transmits a signal, and a reception path (420) may be implemented in a communication node that receives a signal. The transmission path (410) may include a channel coding and modulation block (411), an S-to-P (serial-to-parallel) block (512), an N IFFT (Inverse Fast Fourier Transform) block (413), a P-to-S (parallel-to-serial) block (414), a CP (cyclic prefix) addition block (415), and an UC (up-converter) (UC) (416). The receiving path (420) may include a DC (down-converter) (421), a CP removal block (422), an S-to-P block (423), an N FFT block (424), a P-to-S block (425), and a channel decoding and demodulation block (426). Here, N may be a natural number.

[0081] In the transmission path (410), information bits may be input to a channel coding and modulation block (411). The channel coding and modulation block (411) may perform a coding operation (e.g., a low-density parity check (LDPC) coding operation, a polar coding operation, etc.) and a modulation operation (e.g., a quadrature phase shift keying (QPSK), a quadrature amplitude modulation (QAM), etc.) on the information bits. The output of the channel coding and modulation block (411) may be a sequence of modulation symbols.

[0082] The S-to-P block (412) can convert modulation symbols in the frequency domain into parallel symbol streams to generate N parallel symbol streams. N can be an IFFT size or an FFT size. The N IFFT block (413) can perform an IFFT operation on the N parallel symbol streams to generate signals in the time domain. The P-to-S block (414) can convert the output (e.g., parallel signals) of the N IFFT block (413) into a serial signal to generate a serial signal.

[0083] The CP addition block (415) can insert a CP into a signal. The UC (416) can up-convert the frequency of the output of the CP addition block (415) to an RF (radio frequency) frequency. Additionally, the output of the CP addition block (415) can be filtered at the baseband before up-conversion.

[0084] A signal transmitted from a transmission path (410) may be input to a reception path (420). An operation in the reception path (420) may be the reverse operation of the operation in the transmission path (410). A DC (421) may down-convert the frequency of the received signal to a baseband frequency. A CP removal block (422) may remove a CP from a signal. The output of the CP removal block (422) may be a serial signal. An S-to-P block (423) may convert the serial signal into parallel signals. An N FFT block (424) may perform an FFT algorithm to generate N parallel signals. A P-to-S block (425) may convert the parallel signals into a sequence of modulation symbols. A channel decoding and demodulation block (426) may perform a demodulation operation on the modulation symbols and perform a decoding operation on the result of the demodulation operation to restore data.

[0085] In FIGS. 4A and 4B , Discrete Fourier Transform (DFT) and Inverse DFT (IDFT) may be used instead of FFT and IFFT. Each of the blocks (e.g., components) in FIGS. 4A and 4B may be implemented by at least one of hardware, software, or firmware. For example, some of the blocks in FIGS. 4A and 4B may be implemented by software, and the remaining blocks may be implemented by hardware or a “combination of hardware and software.” In FIGS. 4A and 4B , a block may be subdivided into multiple blocks, multiple blocks may be integrated into a single block, some blocks may be omitted, and blocks supporting other functions may be added.

[0086] Figure 5 is a conceptual diagram illustrating a first embodiment of a system frame in a communication system.

[0087] Referring to FIG. 5, time resources in a communication system can be divided into frame units. For example, system frames can be set consecutively in the time domain of the communication system. The length of a system frame can be 10 ms (milliseconds). The system frame number (SFN) can be set from #0 to #1023. In this case, 1024 system frames can be repeated in the time domain of the communication system. For example, the SFN of the system frame after system frame #1023 can be #0.

[0088] A system frame may include two half frames. A half frame may be 5 ms long. A half frame located at the beginning of the system frame may be referred to as "half frame #0," and a half frame located at the end of the system frame may be referred to as "half frame #1." A system frame may include 10 subframes. A subframe may be 1 ms long. The 10 subframes within a system frame may be referred to as "subframes #0-9."

[0089] Figure 6 is a conceptual diagram illustrating a first embodiment of a subframe in a communication system.

[0090] Referring to FIG. 6, one subframe may include n slots, where n may be a natural number. Accordingly, one subframe may be composed of one or more slots.

[0091] Figure 7 is a conceptual diagram illustrating a first embodiment of a slot in a communication system.

[0092] Referring to Figure 7, a single slot may include one or more symbols. A single slot illustrated in Figure 7 may include 14 symbols. The length of a slot may vary depending on the number and length of symbols contained in the slot. Alternatively, the length of a slot may vary depending on the numerology.

[0093] In a communication system, the numerology applied to physical signals and channels may be variable. The numerology may be variable to meet various technical requirements of the communication system. In a communication system applying CP (cyclic prefix)-based OFDM waveform technology, the numerology may include subcarrier spacing and CP length (or CP type). Table 1 may be a first embodiment of a method for configuring a numerology for a CP-OFDM-based communication system. At least some of the numerologies in Table 1 may be supported depending on the frequency band in which the communication system operates. In addition, the communication system may additionally support numerologies not listed in Table 1.

[0094]

[0095] When the subcarrier spacing is 15 kHz (e.g., μ=0), the slot length can be 1 ms. In this case, one system frame can contain 10 slots. When the subcarrier spacing is 30 kHz (e.g., μ=1), the slot length can be 0.5 ms. In this case, one system frame can contain 20 slots.

[0096] When the subcarrier spacing is 60 kHz (e.g., μ=2), the slot length can be 0.25 ms. In this case, one system frame can contain 40 slots. When the subcarrier spacing is 120 kHz (e.g., μ=3), the slot length can be 0.125 ms. In this case, one system frame can contain 80 slots. When the subcarrier spacing is 240 kHz (e.g., μ=4), the slot length can be 0.0625 ms. In this case, one system frame can contain 160 slots.

[0097] A symbol may be configured as a downlink (DL) symbol, a flexible (FL) symbol, or an uplink (UL) symbol. A slot consisting solely of DL symbols may be referred to as a "DL slot," a slot consisting solely of FL symbols may be referred to as an "FL slot," and a slot consisting solely of UL symbols may be referred to as a "UL slot."

[0098] The slot format can be semi-statically configured by higher layer signaling (e.g., RRC signaling). Information indicating the semi-static slot format can be included in the system information, and the semi-static slot format can be configured cell-specifically. In addition, the semi-static slot format can be additionally configured for each terminal through terminal-specific higher layer signaling (e.g., RRC signaling). The flexible symbol of the cell-specifically configured slot format can be overridden to a downlink symbol or an uplink symbol by terminal-specific higher layer signaling. In addition, the slot format can be dynamically indicated by physical layer signaling (e.g., a slot format indicator (SFI) included in DCI). The semi-statically configured slot format can be overridden by a dynamically indicated slot format. For example, the semi-statically configured flexible symbol can be overridden to a downlink symbol or an uplink symbol by the SFI.

[0099] The reference signal may be a channel state information-reference signal (CSI-RS), a sounding reference signal (SRS), a demodulation-reference signal (DM-RS), a phase tracking-reference signal (PT-RS), etc. The channel may be a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), etc. In the present disclosure, a control channel may mean a PDCCH, a PUCCH, or a PSCCH, and a data channel may mean a PDSCH, a PUSCH, or a PSSCH.

[0100] Figure 8 is a conceptual diagram illustrating a first embodiment of time-frequency resources in a communication system.

[0101] Referring to FIG. 8, a resource consisting of one symbol (e.g., an OFDM symbol) in the time domain and one subcarrier in the frequency domain may be defined as a "RE (resource element)". Resources consisting of one OFDM symbol in the time domain and K subcarriers in the frequency domain may be defined as a "REG (resource element group)". A REG may include K REs. A REG may be used as a basic unit for resource allocation in the frequency domain. K may be a natural number. For example, K may be 12. N may be a natural number. In the slot illustrated in FIG. 7, N may be 14. N OFDM symbols may be used as a basic unit for resource allocation in the time domain.

[0102] In the present disclosure, RB may mean CRB (common RB). Alternatively, RB may mean PRB or VRB (virtual RB). In a communication system, CRB may mean RB that constitutes a set of consecutive RBs (e.g., a common RB grid) based on a reference frequency (e.g., point A). Carriers and / or bandwidth portions may be arranged on the common RB grid. That is, the carrier and / or bandwidth portions may be composed of CRB(s). RBs or CRBs that constitute the bandwidth portions may be referred to as PRBs, and within the bandwidth portions, the CRB index may be appropriately converted to the PRB index.

[0103] Downlink data can be transmitted via the PDSCH. The base station can transmit PDSCH configuration information (e.g., scheduling information) to the terminal via the PDCCH. The terminal can obtain the PDSCH configuration information by receiving the PDCCH (e.g., downlink control information (DCI)). For example, the PDSCH configuration information can include the MCS (modulation coding scheme) used for transmitting and receiving the PDSCH, time resource information of the PDSCH, frequency resource information of the PDSCH, feedback resource information for the PDSCH, etc. The PDSCH can refer to a radio resource through which downlink data is transmitted and received. Alternatively, the PDSCH can refer to the downlink data itself. The PDCCH can refer to a radio resource through which downlink control information (e.g., DCI) is transmitted and received. Alternatively, the PDCCH can refer to the downlink control information itself.

[0104] A terminal can perform a monitoring operation on the PDCCH to receive a PDSCH transmitted from a base station. The base station can inform the terminal of the configuration information for the PDCCH monitoring operation using a higher layer message (e.g., an RRC (radio resource control) message). The configuration information for the PDCCH monitoring operation can include CORESET (control resource set) information and search space information.

[0105] CORESET information may include PDCCH DMRS (demodulation reference signal) information, PDCCH precoding information, PDCCH occasion information, etc. The PDCCH DMRS may be a DMRS used to demodulate the PDCCH. The PDCCH occasion may be a region where the PDCCH can exist. That is, the PDCCH occasion may be a region where DCI can be transmitted. The PDCCH occasion may be referred to as a PDCCH candidate. The PDCCH occasion information may include time resource information and frequency resource information of the PDCCH occasion. In the time domain, the length of the PDCCH occasion may be indicated in symbol units. In the frequency domain, the size of the PDCCH occasion may be indicated in RB units (e.g., in PRB (physical resource block) units or CRB (common resource block) units).

[0106] The search space information may include a coreset identifier (ID) associated with the search space, a period of PDCCH monitoring, and / or an offset. The period and offset of PDCCH monitoring may each be indicated on a slot-by-slot basis. In addition, the search space information may further include an index of the symbol at which the PDCCH monitoring operation begins.

[0107] A base station can configure a bandwidth part (BWP) for downlink communication. The BWP can be configured differently for each terminal. The base station can inform the terminal of the BWP configuration information using higher layer signaling. The higher layer signaling can mean "transmission operation of system information" and / or "transmission operation of RRC (radio resource control) message." The number of BWPs configured for one terminal can be one or more. The terminal can receive BWP configuration information from the base station and check the BWP(s) configured by the base station based on the BWP configuration information. When multiple BWPs are configured for downlink communication, the base station can activate one or more BWPs among the multiple BWPs. The base station can transmit the configuration information of the activated BWP(s) to the terminal using at least one of higher layer signaling, a medium access control (MAC) control element (CE), or DCI. The base station can perform downlink communication using the activated BWP(s). The terminal can identify the activated BWP(s) by receiving configuration information of the activated BWP(s) from the base station, and perform a downlink reception operation in the activated BWP(s).

[0108] Figure 9 is a conceptual diagram illustrating an embodiment of a method for distinguishing types of electromagnetic fields.

[0109] Referring to FIG. 9, a communication system may include a base station (910) and terminals. The terminals (920, 930) may belong to an area (hereinafter referred to as an "electromagnetic field") in which signals radiated from antennas (915) of the base station propagate. The type of electromagnetic field may be classified into a near field or a far field. The type of electromagnetic field may be classified based on the Rayleigh distance. The Rayleigh distance may be expressed as in the following mathematical equation 1.

[0110]

[0111] In mathematical expression 1, R may denote the Rayleigh distance. D_BS may be the maximum length of an antenna array (915) belonging to a transmitter (e.g., a base station (910)), and D_UE may be the maximum length of an antenna array belonging to receivers (e.g., terminals (920, 930)). Lambda may denote the wavelength of a signal used for communication between the base station (910) and terminals (920, 930). Referring to mathematical expression 1, the Rayleigh distance may increase as the length of the antenna array belonging to the base station (910) or the terminals (920, 930) increases. The Rayleigh distance may increase as the wavelength of the signal used for communication between the terminal and the base station (910) becomes shorter. Since frequency and wavelength are inversely proportional to each other, the Rayleigh distance may increase as the frequency of the signal used for communication between the terminals (920, 930) and the base station (910) increases.

[0112] 5G communication (e.g., new radio (NR)) can support communication using frequency range (FR) 1 or FR 2. NR can support beamforming to prevent path attenuation in FR 2 and a multiple input multiple output (MIMO) system to increase data transmission rate. It can be expected that future 6G communication will use a frequency band higher than FR 2 (e.g., a terahertz band). Since 6G communication uses a terahertz band higher than FR 2, a signal having a frequency higher than the frequency of a signal used in NR can be used for communication between terminals (920, 930) and a base station (910) in 6G communication. 6G communication can introduce an extra-large multiple input multiple output (XL-MIMO) system to compensate for path attenuation due to an increase in the frequency band. When the XL-MIMO system is introduced, the size of the antenna array belonging to nodes participating in communication can be increased.

[0113] Due to the aforementioned characteristics of 6G communications (e.g., terahertz bands or XL-MIMO), the Rayleigh distance in NR may be longer in 6G. Therefore, electromagnetic fields considered far-field in NR may be considered near-field in 6G.

[0114] The signals radiated from the antennas (915) of the base station may be spherical waves in the near field. The signals radiated from the antennas (915) of the base station may be considered as planar waves in the far field. A terminal (930) belonging to the far field may consider the signals transmitted from the antennas (915) of the base station as planar waves. The terminal (930) belonging to the far field considering the received signals as planar waves may be referred to as the plane wave assumption. The plane wave assumption will be described below.

[0115] As described above, the type of electromagnetic field can be classified into a near field or a far field. The criterion for distinguishing the type of electromagnetic field may be the distance (hereinafter referred to as the “reference distance”) from the transmission source of the signals (e.g., the antennas (915) of the base station). The reference distance may be as shown in Mathematical Expression 2 below. In Mathematical Expression 2, R, D, phi, and lambda may each represent the reference distance, the maximum length of the antenna array, the maximum allowable phase error, and the wavelength of the signal. The maximum allowable phase error may represent the maximum phase difference between signals received by the antennas belonging to the antenna array or transmitted from the antennas (915).

[0116]

[0117] If the maximum allowable phase error is greater than pi / 8, the plane wave assumption may not be established, and if the plane wave assumption is not established, the Fraunhofer approximation may not be applied. The Fraunhofer approximation may be a method of predicting the diffraction pattern of a signal when the signal is assumed to be a plane wave. If the Fraunhofer approximation is not applied, signals received at receivers (e.g., terminals (920, 930)) may not be determined as a linear function for the index of each antenna belonging to the terminal. The Rayleigh distance in Equation 1 may mean a reference distance when the wavelength in Equation 2 is pi / 8. When signals transmitted from a base station (910) further than the Rayleigh distance are received at the terminal (930), the phase difference between the signals received at the terminal (930) may not exceed pi / 8. If the phase difference between the signals received at the terminal (930) does not exceed , the plane wave assumption may be established.

[0118] If the plane wave assumption holds, the terminal (930) can determine the phase values ​​of the received signals as a linear function for the index of each antenna belonging to the terminal (930). If the plane wave assumption does not hold (for example, if the terminal (920) belongs to the near field), the terminal (920) cannot determine the phase values ​​of the received signals as a linear function for the index of each antenna belonging to the terminal (920). If the plane wave assumption does not hold, the phase values ​​of the signals received at the terminal (920) can be determined as a nonlinear function for the index of each antenna belonging to the terminal (920). If the above-described phase values ​​are determined as a nonlinear function, the factors considered in determining the phase values ​​may be not only the index of each antenna belonging to the terminal (920), but also the incident angle of the signals received at the terminal (920) or the distance between the base station (910) and the terminal. Therefore, the design of the beamforming vector for the terminal (930) belonging to the far field may be different from the design of the beamforming vector for the terminal (920) belonging to the near field. Therefore, the beam failure recovery procedure, which is part of the beam management procedure in 6G communication, may need to be defined differently from the beam failure recovery procedure used in the existing NR. In the beam failure recovery procedure in 6G communication, the procedure for determining the type of electromagnetic field to which the terminals (920, 930) belong or the parameter set used to determine the type of electromagnetic field may be newly defined.

[0119] In NR, beam management procedures may include an initial beam establishment procedure, a beam adjustment procedure, and a beam failure recovery procedure. The initial beam establishment procedure and the beam adjustment procedure may be procedures for determining a transmit beam-receive beam combination having the largest RSRP (reference signal received power) value among transmit beam-receive beam combinations through beam sweeping. The beam failure recovery procedure may be a procedure for determining a new beam when a previously used beam can no longer be used due to environmental factors, etc. The beam failure recovery procedure will be described below.

[0120] Figure 10 is a flowchart illustrating an embodiment of a beam failure recovery procedure.

[0121] Referring to FIG. 10, a base station may transmit one or more synchronization signal blocks (SSBs) for downlink synchronization to a terminal using one or more beams (S1000). The terminal may measure the RSRP values ​​of one or more received beams. Based on the measured RSRP values, the terminal may determine one or more candidate beams (S1010).

[0122] The terminal can determine whether the measured RSRP values ​​fall below a threshold. If the measured RSRP values ​​fall below the threshold, the terminal can determine that a beam failure instance has occurred. A beam failure instance can occur due to poor channel conditions or a temporary phenomenon. The terminal may not determine that a beam failure has occurred simply because a beam failure instance has occurred. The terminal can detect a beam failure when a predetermined number of beam failure instances (e.g., BeamFailureInstanceMaxCount) or more occur.

[0123] A terminal that detects a beam failure can transmit a beam failure recovery request to a base station through a physical random access channel (PRACH) preamble (S1015). The PRACH preamble can be transmitted in an RO (RACH occasion) corresponding to SSBs associated with candidate beams. The base station that receives the PRACH preamble can determine the random access radio network temporary identifier (RA-RNTI) of the terminal based on the RO in which the PRACH preamble is transmitted. The base station can transmit a physical downlink shared channel (PDCCH) including a DCI in which a cyclic redundancy check (CRC) is scrambled with the RA-RNTI to the terminal (S1020). The terminal can decode the PDCCH (S1025). The terminal that decodes the PDCCH can receive a physical uplink shared channel (PDSCH) from the base station.

[0124] A base station that receives a PRACH preamble can obtain identification information about candidate beams (e.g., SSBs associated with the candidate beams or RSRP values ​​of the candidate beams) from the PRACH preamble. The base station can determine one or more beams among the candidate beams to be used for communicating with a terminal. The base station can transmit configuration information about one or more beams used for communicating with the terminal to the terminal through a random access response (RAR) (S1030). The RAR can be included in a PDSCH. A terminal that decodes a PDCCH can receive a PDSCH including an RAR. A terminal that receives a PDSCH can communicate with the base station through one or more newly configured beams (S1035).

[0125] As mentioned in the description of FIG. 9, an electromagnetic field considered as a far-field in NR may be considered a near-field in 6G communications. Since the beamforming vector design for 6G communications is different from that for NR, beams suitable for beamforming in the near-field and beams suitable for beamforming in the far-field may be distinguished. A beam failure recovery procedure in the near-field may need to be redefined. In the newly defined beam failure recovery procedure, a procedure for determining the type of electromagnetic field to which a terminal belongs and parameters required for determining the type of electromagnetic field to which the terminal belongs may be redefined. The operation for determining the type of electromagnetic field to which a terminal belongs may be performed by either a base station or a terminal.

[0126] Fig. 11 is a conceptual diagram illustrating an embodiment of a method for corresponding between a random access channel occasion (RO) and a synchronization signal block (SSB) on a resource grid.

[0127] After transmitting SSBs to a terminal, the base station may transmit system information (e.g., system information block (SIB) 1). The system information may include RACH configuration information. The RACH configuration information may include parameters for RACH configuration (e.g., msg1-fdm or ssb-perRACH-Occasion). msg1-fdm may indicate the number of frequency domains to which ROs are allocated. ssb-perRACH-Occasion may indicate the number of SSBs allocated to one RO. Referring to FIG. 11, it can be confirmed that msg1-fdm is set to 2 and ssb-perRACH-Occasion is set to 1.

[0128]

[0129] Referring to Table 2, the correspondence between SSBs and types of electromagnetic fields can be confirmed when ssb-perRACH-Occasion is 1. Since ssb-perRACH-Occasion is set to 1, one SSB can be mapped to one RO.

[0130] Before establishing a correspondence between SSBs and types of electromagnetic fields, the base station can determine an average Rayleigh distance between terminals belonging to a cell formed by the base station. The Rayleigh distance can be determined between one base station and one terminal. The average Rayleigh distance can mean an average value of the Rayleigh distances between the base station and each terminal. The average value can be one of the arithmetic mean, geometric mean, harmonic mean, weighted mean, median, mode, square mean, and quantile mean. The average Rayleigh distance can be determined based on at least one of the size (or length) of an antenna array belonging to the base station, the size (or length) of each antenna array of terminals belonging to a cell formed by the base station, or a frequency band used for communication between the base station and the terminals.

[0131] The base station can classify each of the 64 SSBs as either a near field SSB (NF SSB) or a far field SSB (FF SSB). The base station can classify each of the SSBs as either an NF SSB or an FF SSB to establish a correspondence between the SSBs and the types of electromagnetic fields. For example, the base station can classify SSBs #0 to SSB 31 as NF SSBs. The base station can classify SSBs #32 to SSB 64 as NF SSBs. Since the beams that the base station transmits to the terminal are associated with the SSBs, once the correspondence between the SSBs and the types of electromagnetic fields is established, the correspondence between the beams and the types of electromagnetic fields can be established.

[0132] Referring to Table 2, 32 NF SSBs and 32 FF SSBs can be identified. However, the number of NF SSBs and the number of FF SSBs may be different. The ratio of the number of NF SSBs to the number of FF SSBs may not be 1:1. The base station can determine the number of NF SSBs and the number of FF SSBs (or the ratio of the number of NF SSBs to the number of FF SSBs) based on the average Rayleigh distance determined before establishing the correspondence between the SSBs and the types of electromagnetic fields. For example, the average Rayleigh distance may increase if the size of the antenna array of the base station (or terminals) increases or the frequency band of the signal used for communication between the base station and terminals increases. If the average Rayleigh distance increases, the base station can determine that the terminals performing communication with the base station are likely to belong to the near field. A base station that determines that terminals communicating with the base station are likely to belong to the near field can set a correspondence relationship between the types of SSBs and electromagnetic fields so that the number of NF SSBs is greater than the number of FF SSBs.

[0133] Once the correspondence between SSBs and electromagnetic field types is established, the base station can generate association information indicating the aforementioned correspondence. The association information can be included in system information and transmitted to the terminal.

[0134]

[0135] Referring to Table 2, a parameter set including parameters associated with information used by a terminal to determine the type of electromagnetic field to which the terminal belongs (hereinafter referred to as "first information") can be identified. The parameters associated with the first information may be parameters necessary for the terminal to obtain the first information. The first information may be information on the distance between the terminal and the base station or information on the maximum phase difference between beams received by antennas belonging to the terminal.

[0136] The parameter set associated with the first information may include at least one of FieldDecisionTimePeriod or FieldDecisionTimeWindow. FieldDecisionTimePeriod may be a period during which the terminal acquires the first information. The terminal may measure the maximum phase difference between beams received by antennas belonging to the terminal according to a period set based on FieldDecisionTimePeriod. The base station may measure the distance between the terminal and the base station according to a period set based on FieldDecisionTimePeriod. The base station may measure the distance between the base station and the terminal based on at least one of a delay time of a PRACH preamble, a positioning reference signal (PRS) for measuring downlink timing, or a sounding reference signal (SRS) for measuring uplink timing. The above-described PRS may be used by the base station to measure downlink time difference of arrival (DL-TDOA), and the SRS may be used to measure uplink time difference of arrival (UL-TDOA). The above-described PRS or SRS can be used to set timing advance between a terminal and a base station. The terminal can send a request to the base station for information on the distance between the terminal and the base station, and the base station can transmit the distance information between the terminal and the base station to the terminal through DCI (downlink control information), MAC (medium access control)-CE (control element), or other RRC (radio resource control) signaling in response to the request.

[0137] FieldDecisionTimeWindow may be a time interval (e.g., a time window) during which the terminal uses the first information. The terminal can determine the type of electromagnetic field to which the terminal belongs based on the first information acquired within the time window.

[0138] The above-described parameter set can be configured by the base station. The base station can configure the parameter set according to the channel status with the terminal. For example, if the base station determines that the channel status with the terminal is poor, the base station can set at least one of FieldDecisionTimePeriod or FieldDecisionTimeWindow to a short value. The base station can transmit the parameter set to the terminal. The base station can transmit the parameter set to the terminal via system information. Alternatively, the base station can transmit the parameter set to the terminal via DCI, MAC-CE, or other RRC signaling.

[0139]

[0140] Referring to Table 4, the first information acquired by the terminal can be confirmed according to the parameter set set according to Table 3. The terminal can measure the maximum phase difference (e.g., phi_1, phi_2, ..., phi_n) between beams received by antennas belonging to the terminal according to the period (e.g., 1 / (t_2 - t_1), ..., 1 / (t_n - t_n-1)) indicated by the set parameter set. The base station can measure the distance (e.g., d_1, d_2, ..., d_n) between the terminal and the base station according to the period indicated by the set parameter set, and can transmit information on the measured distance between the terminal and the base station to the terminal.

[0141]

[0142] The terminal can determine the type of electromagnetic field to which the terminal belongs using the first information within a time window indicated by a parameter set received from the base station. For example, if the time window indicated by the parameter set is [t_1, t_2], the terminal can determine the type of electromagnetic field to which the terminal belongs based on at least one of phi_1 or d_1 at t_1, and can determine the type of electromagnetic field to which the terminal belongs using at least one of phi_2 or d_2 at t_2.

[0143] Hereinafter, a method for determining the type of electromagnetic field by a terminal will be described. The terminal can determine the type of electromagnetic field to which the terminal belongs based on information about the maximum phase difference between beams received by antennas belonging to the terminal, or can determine the type of electromagnetic field to which the terminal belongs based on information about the distance between the terminal and a base station. Information about the maximum phase difference between beams received by antennas belonging to the terminal can be used in a 'phase difference-based electromagnetic field type determination method', and information about the distance between the terminal and a base station can be used in a 'distance-based electromagnetic field type determination method'.

[0144] A method for determining the type of electromagnetic field based on phase difference may be as follows. The terminal may measure the phase values ​​of beams received by antennas belonging to the terminal. The terminal may determine the maximum difference among the differences between the measured phase values. If the maximum difference exceeds pi / 8, the terminal may determine the type of electromagnetic field to which the terminal belongs as a near-field. If the maximum difference is equal to or less than pi / 8, the terminal may determine the type of electromagnetic field to which the terminal belongs as a far-field.

[0145] A distance-based electromagnetic field type determination method may be as follows. The maximum size of the antenna array belonging to the base station may be notified to the terminal through system information transmitted by the base station. The wavelength may be notified to the terminal through the wavelength of the signal received by the base station, and the maximum size of the antenna array belonging to the terminal may be obtained by the terminal itself. Therefore, the terminal may obtain the Rayleigh distance to the base station currently performing communication based on mathematical equation 1. The terminal may obtain the distance between the base station and the terminal based on the distance information between the base station and the terminal received from the base station. If the distance between the base station and the terminal is shorter than the Rayleigh distance, the terminal may determine the type of electromagnetic field to which the terminal belongs as a near-field. If the distance between the base station and the terminal is equal to or longer than the Rayleigh distance, the terminal may determine the type of electromagnetic field to which the terminal belongs as a far-field.

[0146] The following three methods can be considered as a method for determining the type of electromagnetic field to which a terminal belongs based on a phase difference-based electromagnetic field type determination method or a distance-based electromagnetic field type determination method. First, the terminal can determine the type of electromagnetic field to which the terminal belongs based on the first information most recently acquired based on the current time. Second, the terminal can determine the type of electromagnetic field to which the terminal belongs two or more times within a time window indicated by a set of parameters. The terminal can compare the number of times the type of electromagnetic field to which the terminal belongs has been determined as a near-field with the number of times the type of electromagnetic field to which the terminal belongs has been determined as a far-field to derive a comparison result. The terminal can determine the type of electromagnetic field to which the terminal belongs based on the above-described comparison result. For example, the terminal can acquire the first information three times within the time window [t_1, t_3]. Based on the acquired first information, the terminal can determine the type of electromagnetic field to which the terminal belongs three times within the time window [t_1, t_3]. If the number of times the type of electromagnetic field to which the terminal belongs has been determined as a near-field is twice, and the number of times the type of electromagnetic field to which the terminal belongs has been determined as a far-field is once, the terminal can ultimately determine the type of electromagnetic field to which the terminal belongs as a near-field. Third, if the terminal detects a beam failure, the terminal can perform a first information acquisition procedure. The terminal can determine the type of electromagnetic field to which the terminal belongs based on the first information newly acquired through the first information acquisition procedure described above. In the third method, the method by which the terminal uses the newly acquired first information can be the first method described above or the second method described above.

[0147] Referring to Table 5, it can be confirmed that the terminal has determined the type of electromagnetic field to which the terminal belongs as a near-field based on a phase difference-based electromagnetic field type determination method or a distance-based electromagnetic field type determination method.

[0148]

[0149] A terminal can receive beams associated with SSBs from a base station. The terminal can measure RSRP of the received beams. The terminal can determine beams for which an RSRP greater than or equal to a threshold (e.g., 90 dBm) is measured as candidate beams. The terminal may not determine beams for which an RSRP less than or equal to 90 dBm is measured as candidate beams. When the terminal determines the type of electromagnetic field to which the terminal belongs, the terminal can determine first beams that match the determined type of electromagnetic field among the candidate beams based on the determined type of electromagnetic field. The terminal can transmit a PRACH preamble to the base station in an RO corresponding to the SSBs associated with the first beams. The transmitted PRACH preamble may include a beam failure recovery request. The operations of the terminal described above will be described below with reference to Table 6.

[0150] Referring to Table 6, the terminal can receive 64 beams associated with SSB #1 to SSB #64 from the base station. The terminal can measure the RSRP of each of the 64 beams associated with SSB #1 to SSB #64. The terminal can determine beams for which an RSRP of 90 dBm or more is measured as candidate beams.

[0151] For example, the terminal may not determine the beam associated with SSB #0 as a candidate beam because the RSRP of the beam associated with SSB #0 is 87 dBm. The terminal may not transmit a PRACH preamble in RO #0 corresponding to SSB #0. The terminal may determine the beam associated with SSB #1 as a candidate beam because the RSRP of the beam associated with SSB #1 is 103 dBm. Referring to Table 2, SSB #1 is NF SSB, and referring to Table 5, it can be confirmed that the terminal has determined the type of electromagnetic field to which the terminal belongs as a near-field. Therefore, the terminal may determine the beam associated with SSB #1, which is an NF SSB, as the first beam that matches the type of electromagnetic field to which the terminal belongs. The terminal may transmit a PRACH preamble in RO #1 corresponding to SSB #1. The terminal may determine the beam associated with SSB #63 as a candidate beam because the RSRP of the beam associated with SSB #63 is 95 dBm. However, referring to Table 2, it can be confirmed that SSB #63 is FF SSB, and referring to Table 5, it can be confirmed that the terminal has determined the type of electromagnetic field to which the terminal belongs as a near-field field. Therefore, the terminal that has determined the type of electromagnetic field to which the terminal belongs as a near-field field may not determine the beam associated with SSB #63, which is FF SSB, as the first beam that matches the type of electromagnetic field to which the terminal belongs. The terminal may not transmit the PRACH preamble in RO #63 corresponding to SSB #63. If, unlike Table 6, the RSRP of the beam associated with SSB #63 is less than or equal to the threshold, the terminal may not determine the beam associated with SSB #63 as a candidate beam. Therefore, the terminal may not transmit the PRACH preamble in RO #63 corresponding to SSB #63.

[0152] Tables 4 to 6 may be written on the assumption that the terminal determines the type of electromagnetic field to which the terminal belongs. The operation in which the base station establishes the correspondence between SSBs (or beams) and the type of electromagnetic field (e.g., the operation deriving Table 2) and the operation in which the base station sets a parameter set (e.g., the operation deriving Table 3) may be performed in the same manner even when the base station determines the type of electromagnetic field to which the terminal belongs. However, after the correspondence between SSBs and the type of electromagnetic field is established, the base station may not generate or transmit to the terminal the association information indicating the correspondence described above. Below, a beam failure recovery procedure will be described when the base station determines the type of electromagnetic field to which the terminal belongs.

[0153]

[0154] Referring to Table 7, first information (e.g., a distance between a terminal and a base station or a maximum phase difference between beams received by antennas belonging to the terminal) acquired by the base station can be confirmed according to a parameter set set according to Table 3. The base station can measure a distance between the terminal and the base station (e.g., d_1, d_2, ..., d_n) according to a period (e.g., 1 / (t_2 - t_1), ..., 1 / (t_n - t_n-1)) indicated by the set parameter set. The terminal can measure a maximum phase difference (e.g., phi_1, phi_2, ..., phi_n) between beams received by antennas belonging to the terminal according to a period indicated by the set parameter set. The terminal can transmit information on the maximum phase difference between beams received by antennas belonging to the terminal to the base station at a request of the base station. The terminal can transmit information on the maximum phase difference between beams received by antennas belonging to the terminal to the base station through UCI (uplink control information), Msg 1 in a contention-based random access procedure, Msg A in a non-contention-based random access procedure, or other RRC signaling.

[0155]

[0156] A terminal may receive beams associated with SSBs from a base station. The terminal may measure the RSRP of the received beams. The terminal may determine beams for which an RSRP greater than a threshold (e.g., 90 dBm) is measured as candidate beams. The terminal may transmit a PRACH preamble to the base station in an RO corresponding to the SSBs associated with the candidate beams. The transmitted PRACH preamble may include a beam failure recovery request. The terminal may not determine beams for which an RSRP less than 90 dBm is measured as candidate beams. The operations of the terminal described above will be described below with reference to Table 8.

[0157] Referring to Table 8, the terminal can receive 64 beams associated with SSB #1 to SSB #64 from the base station. The terminal can measure the RSRP of each of the 64 beams associated with SSB #1 to SSB #64. The terminal can determine beams for which an RSRP of 90 dBm or more is measured as candidate beams.

[0158] For example, the terminal may not determine the beam associated with SSB #0 as a candidate beam because the RSRP of the beam associated with SSB #0 is 63 dBm. The terminal may not transmit a PRACH preamble in RO #0 corresponding to SSB #0. The terminal may determine the beam associated with SSB #1 as a candidate beam because the RSRP of the beam associated with SSB #1 is 109 dBm. The terminal may transmit a PRACH preamble in RO #1 corresponding to SSB #1. The terminal may determine the beam associated with SSB #63 as a candidate beam because the RSRP of the beam associated with SSB #63 is 99 dBm. The terminal may transmit a PRACH preamble in RO #63 corresponding to SSB #63.

[0159]

[0160] A base station that receives a PRACH preamble from a terminal can determine the type of electromagnetic field to which the terminal belongs using the first information within a time window indicated by a parameter set. For example, if the time window indicated by the parameter set is [t_1, t_2], the base station can determine the type of electromagnetic field to which the terminal belongs based on at least one of phi_1 or d_1 at t_1, and can determine the type of electromagnetic field to which the terminal belongs using at least one of phi_2 or d_2 at t_2.

[0161] Hereinafter, a method for determining the type of electromagnetic field by a base station will be described. The base station can determine the type of electromagnetic field to which a terminal belongs based on information about the maximum phase difference between beams received by antennas belonging to the terminal, or can determine the type of electromagnetic field to which a terminal belongs based on information about the distance between the terminal and the base station. Information about the maximum phase difference between beams received by antennas belonging to the terminal can be used in a 'method for determining the type of electromagnetic field based on a phase difference', and information about the distance between the terminal and the base station can be used in a 'method for determining the type of electromagnetic field based on a distance'.

[0162] A method for determining the type of electromagnetic field based on a phase difference may be as follows. A terminal may measure the phase values ​​of beams received by antennas belonging to the terminal. The terminal may determine the maximum difference value among the differences between the measured phase values. A base station that has received information indicating the maximum difference value from the terminal may determine the type of electromagnetic field to which the terminal belongs as a near field if the maximum difference value exceeds pi / 8. The base station may determine the type of electromagnetic field to which the terminal belongs as a far field if the maximum difference value is equal to or less than pi / 8.

[0163] The method for determining the type of electromagnetic field based on distance can be as follows. The maximum size of the antenna array belonging to the base station can be obtained by the base station itself. The maximum size of the antenna array belonging to the terminal can be notified to the base station through a PRACH preamble, etc. The wavelength can be obtained by the base station itself from the wavelength of the signal transmitted by the base station. Therefore, the base station can obtain the Rayleigh distance with the terminal currently performing communication based on mathematical equation 1. If the distance between the base station and the terminal measured by the base station itself is shorter than the Rayleigh distance, the base station can determine the type of electromagnetic field to which the terminal belongs as a near-field. If the distance between the base station and the terminal is equal to or longer than the Rayleigh distance, the base station can determine the type of electromagnetic field to which the terminal belongs as a far-field.

[0164] The following three methods can be considered as a method for a base station to determine the type of electromagnetic field to which a terminal belongs based on a phase difference-based electromagnetic field type determination method or a distance-based electromagnetic field type determination method. First, the base station can determine the type of electromagnetic field to which a terminal belongs based on the most recently acquired first information as of the current time. Second, the base station can determine the type of electromagnetic field to which a terminal belongs two or more times within a time window indicated by a set of parameters. The base station can compare the number of times the type of electromagnetic field to which a terminal belongs has been determined as a near-field with the number of times the type of electromagnetic field to which a terminal belongs has been determined as a far-field, and derive a comparison result. The base station can determine the type of electromagnetic field to which a terminal belongs based on the above-described comparison result. For example, the base station can acquire the first information three times within a time window [t_1, t_3]. Based on the acquired first information, the base station can determine the type of electromagnetic field to which a terminal belongs three times within the time window [t_1, t_3]. If the number of times the type of electromagnetic field to which the terminal belongs has been determined as a near-field is twice, and the number of times the type of electromagnetic field to which the terminal belongs has been determined as a far-field is once, the base station can finally determine the type of electromagnetic field to which the terminal belongs as a near-field. Third, if the base station receives a PRACH preamble from the terminal, the base station can perform a first information acquisition procedure. The base station can determine the type of electromagnetic field to which the terminal belongs based on the first information newly acquired through the first information acquisition procedure described above. In the third method, the method by which the base station uses the newly acquired first information can be the first method described above or the second method described above.

[0165] Referring to Table 9, it can be confirmed that the base station has determined the type of electromagnetic field to which the terminal belongs as a near-field based on a phase difference-based electromagnetic field type determination method or a distance-based electromagnetic field type determination method.

[0166] A base station that determines the type of electromagnetic field to which a terminal belongs as a near-field can check candidate beams from a PRACH preamble transmitted from the terminal. The base station can determine first beams that match the type of electromagnetic field to which the terminal belongs (e.g., a near-field according to Table 9) among the candidate beams. The base station can transmit an RAR to the terminal for a PRACH preamble transmitted in an RO corresponding to an SSB associated with the first beams. The terminal and the base station can communicate using the first beams. Alternatively, the base station can transmit an RAR to the terminal for a PRACH preamble transmitted in an RO corresponding to an SSB associated with second beams among the first beams having an RSRP exceeding a threshold.

[0167] The operations of the terminal or base station derived from Tables 2 to 9 can be performed identically to the operations presented in the description of FIGS. 12A to 13B below, as long as they are not technically inconsistent. The embodiments illustrated in FIGS. 12A and 12B may be embodiments in which the terminal determines the type of electromagnetic field to which the terminal belongs. The embodiments illustrated in FIGS. 13A and 13B may be embodiments in which the base station determines the type of electromagnetic field to which the terminal belongs.

[0168] FIG. 12a is a flowchart illustrating a first embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0169] Referring to FIG. 12A, the base station can establish a correspondence between each SSB (or beam) and the type of electromagnetic field (S1205). The base station, which has established a correspondence between each SSB (or beam) and the type of electromagnetic field, can transmit SSBs to a terminal using the beams (S1210). A terminal that receives beams associated with SSBs can measure the RSRP of the beams. The terminal can determine candidate beams based on the measured RSRP values ​​(S1215).

[0170] The base station may transmit system information to the terminal (S1220). The system information may include at least one of a parameter set including parameters associated with associated information indicating the above-described correspondence relationship or information used to determine the type of electromagnetic field to which the terminal belongs (hereinafter referred to as “first information”). The terminal receiving the system information may obtain first information (e.g., information on the distance between the terminal and the base station or information on the maximum phase difference between beams received by antennas belonging to the terminal) according to the parameter set (S1225). In order to obtain information on the distance between the terminal and the base station, the terminal may transmit a request for information on the distance between the terminal and the base station to the base station.

[0171] FIG. 12b is a flowchart illustrating a first embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0172] Referring to FIG. 12b, the terminal can detect a beam failure when a predetermined number of beam failure instances (e.g., BeamFailureInstanceMaxCount) or more occur (S1230). The terminal can determine the type of electromagnetic field to which the terminal belongs using first information within a time window indicated by a parameter set received from the base station (S1235). The terminal can transmit a PRACH preamble to the base station in the RO corresponding to SSBs associated with the first beams that match the type of electromagnetic field to which the terminal belongs among the candidate beams (S1240).

[0173] A base station that receives a PRACH preamble can determine an RA-RNTI of a terminal based on an RO in which the PRACH preamble is transmitted. The base station can transmit a DCI with a CRC scrambled with the RA-RNTI to the terminal (S1245). The terminal that receives the DCI can decode the DCI (S1250), and the terminal that decodes the DCI can receive a PDSCH. The base station can obtain identification information for the first beams (e.g., SSBs associated with the first beams or RSRP values ​​of the first beams) from the PRACH preamble transmitted from the terminal. The base station that obtains the identification information for the first beams can transmit an RAR to the terminal for the PRACH preamble transmitted in an RO corresponding to the SSBs associated with the first beams (S1255). The base station can transmit a PDSCH including an RAR to the terminal using the first beams. A terminal and a base station that have received a PDSCH including an RAR may communicate with the terminal using one or more new beams (e.g., first beams) (S1260). Alternatively, the base station may transmit an RAR to the terminal for a PRACH preamble transmitted in an RO corresponding to SSBs associated with second beams among the first beams having an RSRP exceeding a threshold.

[0174] FIG. 13a is a flowchart illustrating a second embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0175] Referring to FIG. 13A, the base station can establish a correspondence between each SSB (or beam) and the type of electromagnetic field (S1305). The base station, which has established a correspondence between each SSB (or beam) and the type of electromagnetic field, can transmit SSBs to a terminal using the beams (S1310). The terminal, which has received the beams associated with the SSBs, can measure the RSRP of the beams. The terminal can determine candidate beams based on the measured RSRP values ​​(S1315).

[0176] A base station can transmit system information to a terminal (S1320). The base station that transmitted the system information can set a parameter set including parameters associated with information used to determine the type of electromagnetic field to which the terminal belongs (hereinafter referred to as “first information”) (S1325). The base station can obtain first information (e.g., information on the distance between the terminal and the base station or information on the maximum phase difference between beams received by antennas belonging to the terminal) according to the parameter set (S1330). In order to obtain information on the maximum phase difference between beams received by antennas belonging to the terminal, the base station can transmit a request to the terminal for information on the maximum phase difference between the beams received by the terminal and the antennas belonging to the terminal.

[0177] FIG. 13b is a flowchart illustrating a second embodiment of a beam failure recovery procedure performed based on the type of electromagnetic field.

[0178] Referring to FIG. 13b, the terminal can detect a beam failure when a predetermined number of beam failure instances (e.g., BeamFailureInstanceMaxCount) or more occur (S1335). The terminal can transmit a PRACH preamble to the base station in the RO corresponding to the SSBs associated with the candidate beams (S1340). The transmitted PRACH preamble can include a beam failure recovery request.

[0179] The base station that receives the PRACH preamble can determine the type of electromagnetic field to which the terminal belongs based on the first information (S1345). The base station can determine the RA-RNTI of the terminal from the RO where the PRACH preamble is transmitted. The base station can transmit the DCI with the CRC scrambled with the RA-RNTI to the terminal (S1350). The terminal that receives the DCI can decode the DCI (S1355), and the terminal that decodes the DCI can receive the PDSCH.

[0180] The base station can identify the candidate beams based on the identification information of the candidate beams included in the PRACH preamble (e.g., SSBs associated with the candidate beams or RSRP values ​​of the candidate beams). The base station can determine the first beams that match the type of electromagnetic field to which the terminal belongs among the candidate beams. The base station can transmit an RAR for the PRACH preamble transmitted in an RO corresponding to the SSBs associated with the first beams (S1360). The terminal that receives the RAR can perform communication with the base station using one or more beams (e.g., the first beams) (S1365). Alternatively, the base station can transmit an RAR to the terminal for the PRACH preamble transmitted in an RO corresponding to the SSBs associated with the second beams among the first beams having an RSRP exceeding a threshold.

[0181] The operations of the method according to the present disclosure can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores information readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0182] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0183] While some aspects of the present disclosure have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most significant method steps may be performed by such a device.

[0184] A programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described in the present disclosure. The field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described in the present disclosure. In general, the methods are preferably performed by some hardware device.

[0185] Although the present disclosure has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present disclosure without departing from the spirit and scope of the present disclosure as set forth in the claims below.

Claims

1. As a terminal method, A step of receiving beams from a base station; A step of receiving system information including instruction information indicating a correspondence between each of the above beams and a type of electromagnetic field; A step of obtaining first information used to determine the type of electromagnetic field to which the terminal belongs based on the above system information; A step of detecting beam failure after acquiring the above first information; A step of determining the type of electromagnetic field to which the terminal belongs based on the first information in response to the beam failure; and Comprising a step of performing a beam failure recovery procedure with the base station based on the type of the determined electromagnetic field, Terminal method.

2. In claim 1, The above correspondence relationship is established based on the correspondence relationship between each of the SSBs (synchronization signal blocks) associated with the beams and the type of electromagnetic field. Terminal method.

3. In claim 1, After receiving the beams, the method further includes a step of measuring RSRP (reference signal received power) values ​​of the beams and determining candidate beams among the beams based on the RSRP values. The steps for performing the above beam failure recovery procedure are: A step of determining first beams corresponding to the determined type of electromagnetic field among the candidate beams based on the above instruction information; A step of transmitting a beam failure recovery request to the base station in a random access channel occasion (RO) corresponding to the SSBs associated with the first beams; receiving a response to the beam failure recovery request from the base station; and Comprising a step of performing communication with the base station through one or more beam(s) determined by the response among the first beams, Terminal method.

4. In claim 1, The system information includes a set of parameters associated with the first information, and the set of parameters includes at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information. Terminal method.

5. In claim 1, The first information includes at least one of information on the distance between the base station and the terminal or information on the maximum phase difference between the beams received by the antennas belonging to the terminal. Terminal method.

6. In claim 4, The first information is obtained according to a period indicated by the period parameter, and the type of the electromagnetic field to which the terminal belongs is determined based on a comparison result between the number of times the type of the electromagnetic field to which the terminal belongs is determined as a near field and the number of times the type of the electromagnetic field to which the terminal belongs is determined as a far field within a time window indicated by the time window parameter. Terminal method.

7. In claim 5, The step of obtaining the above first information is: A step of transmitting a request for information on the distance between the base station and the terminal to the base station after receiving the above system information; and In response to the request, comprising a step of obtaining information on the distance between the base station and the terminal from the base station, Terminal method.

8. In claim 5, The step of obtaining the above first information is: A step of measuring phase differences between the beams received by the antennas belonging to the terminal after receiving the above system information; and A step of determining the maximum phase difference among the above phase differences and obtaining information on the maximum phase difference, Terminal method.

9. In claim 5, The step of determining the type of electromagnetic field to which the terminal belongs is performed based on at least one of a comparison result between the maximum phase difference indicated by the information on the maximum phase difference and a phase difference threshold or a comparison result between the distance between the base station and the terminal indicated by the information on the distance and a distance threshold. Terminal method.

10. As a method of base station, A step of transmitting beams to a terminal; A step of establishing a correspondence between each of the SSBs associated with the above beams and the type of electromagnetic field; A step of transmitting system information including instruction information indicating the above correspondence relationship; and A step of performing a beam failure recovery procedure with the terminal that detects a beam failure after transmitting the above system information, Base station method.

11. In claim 10, In the step of establishing the above correspondence relationship, each of the SSBs associated with the beams is determined to be either a near field SSB or a far field SSB. Base station method.

12. In claim 11, Before setting the above correspondence relationship, further comprising a step of determining an average Rayleigh distance between terminals belonging to a cell formed by the base station and the base station, A ratio of one or more SSB(s) determined as the near-field SSB among the above SSBs and one or more SSB(s) determined as the far-field SSB among the above SSBs is determined based on the average Rayleigh distance, and the average Rayleigh distance is determined based on at least one of the maximum length of the antenna array belonging to the base station, the maximum length of the antenna array belonging to the terminals, or the frequency band used for communication between the base station and the terminals. Base station method.

13. In claim 10, After setting the above correspondence relationship, further comprising a step of setting a set of parameters associated with the first information used to determine the type of the electromagnetic field to which the terminal belongs, The above system information includes the above parameter set, Base station method.

14. In claim 13, The above parameter set includes at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information. Base station method.

15. In claim 10, A step of receiving a request for information on the distance between the base station and the terminal from the terminal after transmitting the above system information; A step of measuring the distance between the base station and the terminal in response to the request; and Comprising a step of transmitting distance information indicating the distance to the terminal, Base station method.

16. In claim 15, The above distance is measured based on at least one of the delay time of the PRACH (physical random access channel) preamble received from the terminal or one or more signal(s) used to set timing advance between the terminal and the base station. Base station method.

17. In claim 10, The steps for performing the above beam failure recovery procedure are: A step of receiving a beam failure recovery request from the terminal that has detected the beam failure in a RO (random access channel occasion) corresponding to the SSBs associated with the first beams corresponding to the type of electromagnetic field to which the terminal belongs as determined by the terminal; a step of transmitting a response to the beam failure recovery request to the terminal; and Comprising a step of performing communication with the terminal using one or more beam(s) determined by the above response, Base station method.

18. As a terminal, Contains at least one processor, At least one processor of the terminal, Receive beams from a base station; Receive system information including instruction information indicating a correspondence between each of the above beams and the type of electromagnetic field; Obtaining first information used to determine the type of electromagnetic field to which the terminal belongs based on the above system information; After acquiring the above first information, detecting beam failure; In response to the beam failure, determining the type of electromagnetic field to which the terminal belongs based on the first information; and Causing the base station to perform beam failure recovery procedures based on the type of electromagnetic field determined above, Terminal.

19. In claim 18, The system information includes a set of parameters associated with the first information, and the set of parameters includes at least one of a period parameter indicating a period in which the terminal acquires the first information or a time window parameter indicating a time window in which the terminal uses the first information. Terminal.

20. In claim 18, The first information includes at least one of information on the distance between the base station and the terminal or information on the maximum phase difference between the beams received by the antennas belonging to the terminal. Terminal.

Images