Device and method for estimating direction in wireless communication system

Abstract

A communication system is provided. The communication system supports higher data rates of a fourth generation (4G) communication system beyond Long Term Evolution (LTE). A first device in a wireless communication system is provided. The device includes an antenna array, at least one transceiver, and at least one processor. The transceiver is configured to send a signal by using a beam set, and receive a signal indicating at least one beam in the beam set from a second device. The processor is configured to determine an auxiliary beam pair based on at least one beam. The transceiver is configured to send a reference signal to the second device by using the auxiliary beam pair, and receive feedback information related to the auxiliary beam pair from the second device. At least one processor is configured to determine a communication direction related to the second device based on the feedback information.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly to an apparatus and method for estimating a direction in a wireless communication system. Background Art

[0002] In order to meet the growing demand for wireless data traffic since the deployment of the fourth generation (4G) communication system, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "beyond 4G networks" or "post-LTE systems."

[0003] 5G communication systems are considered to be implemented in higher frequency (mmWave) bands (e.g., 60 GHz band) in order to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are discussed in 5G communication systems.

[0004] In addition, in the 5G communication system, development is underway for system network improvements based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, collaborative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc.

[0005] In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coded modulation (ACM) and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies have been developed.

[0006] To overcome the path loss problem caused by the characteristics of ultra-high frequency bands (e.g., mmWave), 5G communication systems are managed by using a beamforming scheme to increase signal gain. The direction of the transmitted or received signal needs to be determined more accurately to achieve smooth beamforming communication. At the same time, if the accuracy of direction estimation is increased by simply using many beams, the time required for direction determination may increase.

[0007] The above information is presented as background information only to assist with understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art to the present disclosure. Summary of the invention

[0008] Some aspects of the present disclosure are to solve at least the above problems and / or disadvantages and provide at least the advantages described below. Accordingly, one aspect of the present disclosure is to provide an apparatus and method for more accurately estimating the direction of a transmitted or received signal in a wireless communication system.

[0009] Another aspect of the present disclosure is to provide an apparatus and method for estimating a direction of a signal with low overhead in a wireless communication system.

[0010] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0011] According to one aspect of the present disclosure, a first device in a wireless communication system is provided. The device includes an antenna array, at least one transceiver, and at least one processor. At least one transceiver is configured to send a signal by using a beam set, and receive a signal indicating at least one beam in the beam set from a second device, and at least one processor is configured to determine an auxiliary beam pair based on at least one beam. At least one transceiver is configured to send a reference signal to the second device by using the auxiliary beam pair, and receive feedback information related to the auxiliary beam pair from the second device. At least one processor is configured to determine a communication direction related to the second device based on the feedback information.

[0012] According to another aspect of the present disclosure, a method for operating a first device in a wireless communication system is provided. The method includes: transmitting a signal by using a beam set, receiving a signal indicating at least one beam in the beam set from a second device, determining an auxiliary beam pair based on at least one beam, transmitting a reference signal to the second device by using the auxiliary beam pair, receiving feedback information related to the auxiliary beam pair from the second device, and determining a communication direction related to the second device based on the feedback information.

[0013] Apparatuses and methods according to various embodiments may more accurately determine the communication direction of a signal required to achieve smooth beamforming communication.

[0014] Apparatuses and methods according to various embodiments may estimate a direction to reduce overhead due to beam training by using an auxiliary beam pair.

[0015] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses various embodiments of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Certain embodiments and other aspects, features and advantages of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 A wireless communication system according to an embodiment of the present disclosure is illustrated;

[0018] Figure 2 FIG. 1 illustrates a configuration of a base station in a wireless communication system according to an embodiment of the present disclosure;

[0019] Figure 3 FIG. 1 illustrates a configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure;

[0020] Figure 4A illustrates a configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure;

[0021] Figure 4B illustrates a configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure;

[0022] Figure 4C illustrates a configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure;

[0023] Figure 5 A flowchart for direction estimation of a first device according to an embodiment of the present disclosure is illustrated;

[0024] Figure 6 illustrates an example of direction estimation according to an embodiment of the present disclosure;

[0025] Figure 7 A flowchart for determining a beam set by a first device according to an embodiment of the present disclosure is illustrated;

[0026] Figure 8 illustrates an example of a beam width according to an embodiment of the present disclosure;

[0027] Fig. 9 A flowchart of a first apparatus for determining an auxiliary beam pair according to an embodiment of the present disclosure is illustrated;

[0028] Fig.10 illustrates an example of an auxiliary beam pair according to an embodiment of the present disclosure;

[0029] Fig.11 illustrates an example of direction estimation in inter-vehicle communication according to an embodiment of the present disclosure;

[0030] Fig. 12A illustrates an example of direction tracking in inter-vehicle communication according to an embodiment of the present disclosure;

[0031] Fig. 12B An example of direction tracking by changing the traveling direction in inter-vehicle communication according to an embodiment of the present disclosure is illustrated;

[0032] Fig. 12C illustrates an example of direction estimation by changing a reference direction in inter-vehicle communication according to an embodiment of the present disclosure;

[0033] Fig.13A illustrates a graph showing the performance of beamwidth according to an embodiment of the present disclosure;

[0034] Fig. 13B illustrates a graph showing the performance of beamwidth according to an embodiment of the present disclosure;

[0035] Fig.14A FIGURES illustrate a graph showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure;

[0036] Fig. 14B FIGURES illustrate a graph showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure;

[0037] Fig. 14C FIGURES illustrate a graph showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure; and

[0038] Fig.14D FIGURES illustrate graphs showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure.

[0039] Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. DETAILED DESCRIPTION

[0040] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these specific details are considered to be exemplary only. Accordingly, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and configurations may be omitted for clarity and brevity.

[0041] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be clear to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0042] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0043] Hereinafter, various embodiments will be described from the perspective of hardware. However, various embodiments include techniques using both hardware and software, and thus various embodiments may not exclude the perspective of software.

[0044] Hereinafter, the present disclosure relates to an apparatus and method for more accurately estimating a communication direction of a signal in a wireless communication system. Specifically, the present disclosure includes a technology for obtaining information about a signal direction required for smooth communication by using a beamforming scheme in a wireless communication system.

[0045] In the following description, for the convenience of explanation, the following terms are exemplified, including terms indicating signals (e.g., signal, reference signal, information), terms indicating communication nodes (e.g., base station, terminal, vehicle, and electronic device), terms indicating elements of devices, etc. Accordingly, the present disclosure is not limited to the following terms, and other terms having the same technical meanings may be used.

[0046] In addition, the present disclosure includes terms used in some communication protocols (eg, the 3rd Generation Partnership Project (3GPP)) to explain various embodiments, but the terms correspond only to examples. Various embodiments can be easily modified and then applied to another communication system.

[0047] Figure 1 The wireless communication system according to an embodiment of the present disclosure is shown in FIG. Figure 1 The diagram shows a base station 110 , a terminal 120 , and a terminal 130 , which are some nodes using a wireless channel in a wireless communication system.

[0048] The base station 110 is a network infrastructure that provides wireless connections to the terminals 120 and 130. The base station 110 has a coverage area defined as a specific geographical area based on the distance at which the base station 110 can send signals. The base station 110 may be referred to as an "access point (AP)", "eNodeB (eNB)", "fifth generation node", "wireless point" or other terms having technical meanings equivalent thereto. According to various embodiments, the base station 110 may be connected to at least one "transmission / reception point (TRP)". The base station 110 may transmit a downlink signal to the terminal 120 or 130 or receive an uplink signal from the terminal 120 or 130 through at least one TRP.

[0049] Each of the terminals 120 and 130 is a device used by a user and communicates with the base station 110 through a wireless channel. In some cases, at least one of the terminals 120 and 130 may be operated without user involvement. That is, at least one of the terminals 120 and 130 is a device configured to perform machine type communication (MTC) and may not be carried by a user. Each of the terminals 120 and 130 may be referred to as a "user equipment (UE)", "mobile station", "subscriber station", "customer premises equipment (CPE)", "remote terminal", "wireless terminal", "electronic device", "vehicle terminal", "user equipment" or other terms having technical meanings equivalent thereto.

[0050] The base station 110 and the terminals 120 and 130 can transmit and receive wireless signals in a millimeter wave (mmWave) frequency band (e.g., 28 GHz, 30 GHz, 38 GHz, and 60 GHz). In order to improve channel gain, the base station 110 and the terminals 120 and 130 can perform beamforming. Beamforming may include transmit beamforming and receive beamforming. That is, the base station 110 and the terminals 120 and 130 may assign directionality to a transmitted signal or a received signal. To this end, the base station 110 and the terminals 120 and 130 may select service beams 112, 113, 121, and 131 through a beam search process or a beam management process. Communication after selecting the service beams 112, 113, 121, and 131 may be performed through resources having a quasi-co-location (QCL) relationship with resources used for transmission of the service beams 112, 113, 121, and 131.

[0051] If a large-scale characteristic of a channel through which symbols have been transmitted on a first antenna port can be inferred from a channel through which symbols have been transmitted on a second antenna port, then the first antenna port and the second antenna port may be considered to have a QCL relationship therebetween. For example, the large-scale characteristic may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial receiver parameters.

[0052] The base station 110 can send a signal to the terminal 120 by using a beam. The transmitted signal has a directional characteristic, and thus the beam direction needs to be appropriately configured for smooth beamforming communication. The base station 110 can estimate the direction related to the terminal 120, and send a signal by using a beam corresponding to the estimated direction. The direction related to the terminal 120 means the direction in which the signal of the base station 110 is transmitted to the terminal 120, that is, the angle of departure (AoD) from which the signal starts, or means the direction in which the signal of the terminal 120 is received, that is, the angle of arrival (AoA) from which the signal arrives. Hereinafter, the present disclosure describes a method for improving communication efficiency by more accurately estimating the communication direction of the actually transmitted signal.

[0053] According to various embodiments, a beam means a spatial stream of a signal in a wireless channel, and may be generated by one or more antennas (or antenna elements), and the generation process may be referred to as beamforming. According to various embodiments, an antenna array in which a plurality of antenna elements are concentrated may be used, and in this case, the shape (i.e., coverage) of the signal gain may have directivity. A beam for signal transmission may be indicated by a transmission beam, or a beam for signal reception may be indicated by a reception beam.

[0054] According to various embodiments, if a device (base station or terminal) transmits a signal in the direction of a transmit beam, the signal gain of the device can be increased. If a signal is transmitted by using a transmit beam, the signal can be transmitted through a spatial domain transmit filter of the signal transmitting side (ie, a transmitting node). If a signal is transmitted by using multiple transmit beams, the transmitting node can transmit the signal while changing the spatial domain transmit filter. For example, if the signal is transmitted by exactly the same transmit beam, the transmitting node can transmit the signal through the same spatial domain transmit filter. For example, if the terminal (UE) receives a CSI-RS for receive beam search (eg, 3GPP TS 38.214 repetition = "on"), the terminal can assume that the CSI-RS is transmitted through the same spatial domain transmit filter.

[0055] According to various embodiments, if a device (base station or terminal) receives a signal in the direction of a receive beam, the signal gain of the device can be increased. If a signal is transmitted by using a receive beam, the signal can be received by a spatial domain receive filter of a signal receiving side (ie, a receiving node). For example, if a terminal simultaneously receives several signals sent by using different beams, the terminal can receive the signal by using a single spatial domain receive filter, or can receive the signal by using multiple simultaneous spatial domain receive filters.

[0056] In addition, in the detailed description, according to various embodiments, the reference signal can be used as a signal transmitted by using a beam, and can include, for example, a demodulation reference signal (DM-RS), a channel state information reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), and a sounding reference signal (SRS). In addition, as a configuration of each reference signal, an IE such as a CSI-RS resource or an SRS resource can be used, and the above configuration may include beam-associated information. The beam-associated information may mean: whether the corresponding configuration (e.g., a CSI-RS resource) uses a spatial domain filter that is exactly the same as or different from another configuration (e.g., another CSI-RS resource in the same CSI-RS resource set); which reference signal the corresponding configuration is quasi-co-located (QCL); or if the corresponding configuration is already quasi-co-located (QCL), which QCL type (e.g., QCL type A, B, C, and D) the QCL corresponds to. The QCL type may be defined as follows.

[0057] - "QCL Type A": {Doppler shift, Doppler spread, average delay, delay spread}

[0058] - "QCL Type B": {Doppler shift, Doppler spread}

[0059] - "QCL Type C": {Doppler shift, average delay}

[0060] - "QCL Type D": {spatial reception parameters}

[0061] In the detailed description, according to various embodiments, the terminal may measure the quality of the beam in order to obtain the cell quality or the BWP quality. The terminal may obtain the quality of the beam based on the CSI-RS or the SS / PBCH block.

[0062] For example, reference has been made to Figure 1 The communication between the base station and the terminal is described as a system in which beamforming is operated, but various embodiments are not limited thereto. The direction estimation scheme in the present disclosure can be applied to side links including device-to-device (D2D), vehicle-to-everything (V2X), etc.

[0063] In a multiple-input multiple-output (MIMO) system using multiple antennas for a transmitter and / or a receiver, obtaining information for a channel is considered to be very important, and research has been conducted to utilize the MIMO technology. In particular, a beamforming communication system employing the MIMO technology is required to more accurately estimate a transmission direction or a reception direction of a signal (hereinafter, a communication direction), in other words, an angle of a transmitted signal (angle of departure, AoD) and an angle of a received signal (angle of arrival, AoA).

[0064] Figure 2FIG. 1 illustrates a configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0065] refer to Figure 2 It can be understood as the configuration of the base station 110. The term "... unit" or the end of a word (such as "... device (or)", "... device (er)", etc.) used hereinafter may indicate a unit that processes at least one function or operation, and this may be embodied by hardware, software, or a combination of hardware and software.

[0066] refer to Figure 2 , the base station 110 includes a wireless communication unit 210 , a backhaul communication unit 220 , a storage unit 230 and a control unit 240 .

[0067] The wireless communication unit 210 performs a function for sending or receiving a signal through a wireless channel. For example, the wireless communication unit 210 performs a conversion function between a baseband signal and a bit stream according to the physical layer protocol of the system. For example, when sending data, the wireless communication unit 210 generates a complex signal by encoding and modulating the transmission bit stream. In addition, when receiving data, the wireless communication unit 210 reconstructs the received bit stream by demodulating and decoding the baseband signal. In addition, the wireless communication unit 210 up-converts the baseband signal to a radio frequency (RF) band signal, and then transmits the converted RF band signal through an antenna, and down-converts the RF band signal received by the antenna to a baseband signal.

[0068] To this end, the wireless communication unit 210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. In addition, the wireless communication unit 210 may include multiple transmission / reception paths. In addition, the wireless communication unit 210 may include at least one antenna array configured by multiple antenna elements. Considering hardware, the wireless communication unit 210 may be configured by a digital unit and an analog unit, and the analog unit may include multiple subunits according to operating power, operating frequency, etc.

[0069] The wireless communication unit 210 may transmit or receive a signal. For example, the wireless communication unit 210 may transmit a synchronization signal, a reference signal, system information, a message, control information, or data. In addition, the wireless communication unit 210 may perform beamforming. The wireless communication unit 210 may apply a beamforming weight to the transmitted or received signal based on the configuration of the control unit 240 so as to give the signal directivity.

[0070] As described above, the wireless communication unit 210 can transmit and receive signals. Accordingly, all or part of the wireless communication unit 210 may be referred to as a "transmitting unit", "receiving unit" or "transceiver unit". In addition, in the following description, transmission and reception through a wireless channel may be understood as including the aforementioned processing of the wireless communication unit 210.

[0071] The backhaul communication unit 220 provides an interface for performing communication with other nodes within the network. That is, the backhaul communication unit 220 converts a bit stream sent from the base station 110 to another node (e.g., another access node, another base station, a higher node, a core network, etc.) into a physical signal, and converts a physical signal received from another node into a bit stream.

[0072] The storage unit 230 stores data such as basic programs, application programs, and configuration information for the operation of the base station 110. The storage unit 230 may be configured as a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 230 provides the stored data in response to a request of the control unit 240. According to various embodiments, the storage unit 230 may store direction information (or may be referred to as angle information) for each beam of an auxiliary beam pair (ABP) or each beam of a beam set to be operated in the base station 110. According to an embodiment, the direction information may be expressed as a type of array response vector.

[0073] The control unit 240 controls the overall operation of the base station 110. For example, the control unit 240 sends and receives signals through the wireless communication unit 210 or the backhaul communication unit 220. In addition, the control unit 240 records data in the storage unit 230 and reads data from the storage unit 230. In addition, the control unit 240 can perform the functions of the protocol stack required in the communication protocol. To this end, the control unit 240 may include at least one processor.

[0074] According to various embodiments, the control unit 240 may include a beam set determination unit 241, an auxiliary beam pair determination unit 243, and a direction determination unit 245. The beam set determination unit 241 may determine a beam set for performing beam training. According to various embodiments, the beam of the beam set may have a larger beam width than the beam of the auxiliary beam pair described later. The auxiliary beam pair determination unit 243 may determine an auxiliary beam pair for more accurately estimating a direction. The direction determination unit 245 may estimate a direction, that is, a transmission angle or a reception angle of a signal transmitted by using a beam of an auxiliary beam pair, the estimation being based on feedback information about the signal. The process of estimating a direction in the present disclosure may include a process of determining a suitable array response vector to be applied to an antenna array. The beam set determination unit 241, the auxiliary beam pair determination unit 243, and the direction determination unit 245 may be: instructions / codes that at least temporarily reside in the control unit 240 as a stored instruction set or code; a storage space for storing instructions / codes; a part of a circuit that configures the control unit 240; or a module that performs the functions of the control unit 240. According to various embodiments, the control unit 240 may control the base station 110 to perform operations according to various embodiments described later.

[0075] Figure 3 A configuration of a terminal in a wireless communication system according to an embodiment of the present disclosure is illustrated. Figure 3 The configuration illustrated in the figure may be understood as the configuration of the terminal 120. The term "... unit" or the end of a word (such as "... device (or)", "... device (er)", etc.) used hereinafter may indicate a unit that processes at least one function or operation, and this may be embodied by hardware, software, or a combination of hardware and software.

[0076] refer to Figure 3 The terminal 120 includes a communication unit 310 , a storage unit 320 and a control unit 330 .

[0077] The communication unit 310 performs a function for sending or receiving a signal through a wireless channel. For example, the communication unit 310 performs a conversion function between a baseband signal and a bit stream according to the physical layer protocol of the system. For example, when sending data, the communication unit 310 generates a complex signal by encoding and modulating the transmission bit stream. In addition, when receiving data, the communication unit 310 reconstructs the received bit stream by demodulating and decoding the baseband signal. In addition, the communication unit 310 up-converts the baseband signal to an RF band signal, and then transmits the converted RF band signal through an antenna, and down-converts the RF band signal received by the antenna to a baseband signal. For example, the communication unit 310 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0078] In addition, the communication unit 310 may include multiple transmit / receive paths. In addition, the communication unit 310 may include an antenna unit. The communication unit 310 may include at least one antenna array including multiple antenna elements. Considering the hardware, the communication unit 310 may be configured by a digital circuit and an analog circuit (e.g., a radio frequency integrated circuit (RFIC)). The digital circuit and the analog circuit may be implemented as a single package. In addition, the communication unit 310 may include multiple RF chains. In addition, the communication unit 310 may perform beamforming. The communication unit 310 may apply beamforming weights to the transmitted or received signal based on the configuration of the control unit 330 so as to give signal directivity. According to an embodiment, the communication unit 310 may include a radio frequency (RF) block (or RF unit). The RF block may include a first RF circuit (line) related to an antenna and a second RF circuit (line) related to baseband processing. The first RF circuit may be referred to as RF-A (antenna). The second RF circuit may be referred to as RF-B (baseband).

[0079] In addition, the communication unit 310 can send or receive a signal. The communication unit 310 can receive a downlink signal. The downlink signal may include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS) and a demodulation (DM)-RS), system information (e.g., MIB, SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data. In addition, the communication unit 310 may send an uplink signal. The uplink signal may include a signal related to random access (e.g., a random access preamble (RAP) (or message 1 (Msg1), message 3 (Msg3)), a reference signal (e.g., a sounding reference signal (SRS)), a DM-RS), etc. In addition, the communication unit 310 may include different communication modules to process signals in different frequency bands. In addition, the communication unit 310 may include multiple communication modules for supporting a variety of different wireless connection technologies. For example, different wireless connection technologies may include Bluetooth Low Energy (BLE), Wireless Fidelity (Wi-Fi), WiFi Gigabyte (WiGig), cellular networks (e.g., Long Term Evolution (LTE) and New Radio (NR)), etc. In addition, different frequency bands may include Super High Frequency (SHF) (e.g., 2.5 GHz and 5 GHz) bands and millimeter (mm) wave (e.g., 38 GHz, 60 GHz) bands. In addition, the communication unit 310 may use the same type of wireless connection technology for different frequency bands (e.g., unlicensed bands for Licensed Assisted Access (LAA), and Citizens Broadband Radio Service (CBRS) (e.g., 3.5 GHz)).

[0080] As described above, the communication unit 310 transmits and receives signals. Accordingly, all or part of the communication unit 310 may be referred to as a "transmitting unit", "receiving unit" or "transceiver unit". In addition, in the following description, transmission and reception through a wireless channel may be understood as including the aforementioned processing of the communication unit 310.

[0081] The storage unit 320 stores data such as basic programs, applications, and configuration information for the operation of the terminal 120. The storage unit 320 may be configured as a volatile memory, a nonvolatile memory, or a combination of a volatile memory and a nonvolatile memory. The storage unit 320 provides the stored data in response to a request of the control unit 330. According to various embodiments, the storage unit 320 may store the direction of each beam for the auxiliary beam pair or each beam of the beam set to be operated in the terminal 120.

[0082] The control unit 330 controls the overall operation of the terminal 120. For example, the control unit 330 sends and receives signals through the communication unit 310. In addition, the control unit 330 records data in the storage unit 320 and reads data from the storage unit 320. In addition, the control unit 330 can perform the functions of the protocol stack required in the communication protocol. To this end, the control unit 330 may include at least one processor or microprocessor, or may be a part of a processor. In addition, the control unit 330 and a part of the communication unit 310 may be referred to as a communication processor (CP). The control unit 330 may include various modules for performing communication.

[0083] According to various embodiments, the control unit 330 may include a beam set determination unit 331, an auxiliary beam pair determination unit 333, and a direction determination unit 335. The beam set determination unit 331, the auxiliary beam pair determination unit 333, and the direction determination unit 335 correspond to the beam set determination unit 241, the auxiliary beam pair determination unit 243, and the direction determination unit 245 of the base station 110, respectively, and thus a detailed description of overlapping elements will be omitted. The beam set determination unit 331, the auxiliary beam pair determination unit 333, and the direction determination unit 335 may be: instructions / codes at least temporarily residing in the control unit 330 as an instruction set or code stored in the storage unit 320; a storage space storing instructions / codes; a part of a circuit configuring the control unit 330; or a module performing the functions of the control unit 330. According to various embodiments, the control unit 330 may control the terminal to perform operations according to various embodiments described later.

[0084] Figure 3 The configuration of the terminal illustrated in FIG. 1 corresponds only to an example of the terminal, and the terminal is not limited to Figure 3 That is, according to various embodiments, a part of the configuration may be added, removed, or changed.

[0085] Figure 4A A configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0086] Figure 4B A configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0087] Figure 4C The diagram illustrates a configuration of a communication unit in a wireless communication system according to an embodiment of the present disclosure. Figure 4A , Figure 4B and Figure 4C Graphics Figure 2 The wireless communication unit 210 or Figure 3 An example of a specific configuration of the communication unit 310 is shown in FIG. Specifically, Figure 4A , Figure 4B and Figure 4C The element that performs beam forming is shown in FIG. Figure 2 The wireless communication unit 210 or Figure 3 Part of the communication unit 310 in.

[0088] refer to Figure 4A , the wireless communication unit 210 or the communication unit 310 includes a coding and modulation unit 402 , a digital beamforming unit 404 , a plurality of transmission paths 406 - 1 to 406 -N, and an analog beamforming unit 408 .

[0089] The coding and modulation unit 402 performs channel coding. For channel coding, at least one of a low density parity check (LDPC) code, a convolutional code, and a polar code may be used. The coding and modulation unit 402 generates modulation symbols by performing constellation mapping.

[0090] The digital beamforming unit 404 performs beamforming on a digital signal (e.g., a modulation symbol). To this end, the digital beamforming unit 404 multiplies the modulation symbol by a beamforming weight. The beamforming weight is used to change the size and phase of the signal and may be referred to as a "precoding matrix", "precoder", etc. The digital beamforming unit 404 outputs the modulation symbol that has been subjected to digital beamforming to a plurality of transmission paths 406-1 to 406-N. According to a multiple-input multiple-output (MIMO) transmission scheme, the modulation symbol may be multiplexed or the same modulation symbol may be provided to a plurality of transmission paths 406-1 to 406-N.

[0091] Multiple transmission paths 406-1 to 406-N convert digital signals that have been subjected to digital beamforming into analog signals. To this end, each of the multiple transmission paths 406-1 to 406-N may include an inverse fast Fourier transform (IFFT) calculation unit, a cyclic prefix (CP) insertion unit, a DAC, and an up-conversion unit. The CP insertion unit is designed for an orthogonal frequency division multiplexing (OFDM) scheme and may be excluded in another physical layer scheme (e.g., filter bank multi-carrier (FBMC)). That is, multiple transmission paths 406-1 to 406-N provide independent signal processing processes for multiple streams generated by digital beamforming, respectively. However, according to the implementation method, a portion of the elements of multiple transmission paths 406-1 to 406-N may be shared.

[0092] The analog beamforming unit 408 performs beamforming on the analog signal. To this end, the digital beamforming unit 404 multiplies the analog signal by the beamforming weight. The beamforming weight is used to change the magnitude and phase of the signal. Specifically, according to the connection structure between the multiple transmission paths 406-1 to 406-N and the antenna, it can be as follows: Figure 4B or Figure 4C The analog beamforming unit 408 is configured as shown in FIG.

[0093] refer to Figure 4B , the signal input to the analog beamforming unit 408 undergoes phase / size conversion and amplification operations, and is then sent through the antenna. The signal in the path is sent through different antenna groups (i.e., antenna arrays). Regarding the processing of the signal input through the first path, the signal is converted by the phase / size conversion unit (412-1-1 to 412-1-M) to (412-N-1 to 412-NM) into a signal stream including signals with exactly the same phase or size or different phases or sizes, and the converted signal included in the signal stream is amplified by the amplifier (414-1-1 to 414-1-M) to (414-N-1 to 414-NM), and then the amplified signal is sent through the antenna respectively.

[0094] refer to Figure 4C, the signal input to the analog beamforming unit 408 undergoes phase / size conversion and amplification operations, and is then sent through the antenna. The signal in the path is sent through exactly the same antenna group (i.e., antenna array). Regarding the processing of the signal input through the first path, the signal is converted by the phase / size conversion units 412-1-1 to 412-1-M into a signal stream including signals with exactly the same phase or size or different phases or sizes, and the converted signal included in the signal stream is amplified by amplifiers 414-1-1 to 414-1-M. In order to send through a single antenna array, the amplified signals are added together based on the antenna elements by adding units 416-1-1 to 416-1-M, and the added signals are then sent through the antennas respectively.

[0095] Figure 4B An example of using independent antenna arrays for transmit paths is shown, and Figure 4C An example of sharing a single antenna array between transmission paths is illustrated. However, according to another embodiment, some transmission paths may use independent antenna arrays, and the remaining transmission paths may share a single antenna array. In addition, according to yet another embodiment, a switchable structure between transmission paths and antenna arrays may be applied, thereby allowing the use of a structure that changes adaptively according to the situation.

[0096] Figures 1 to 4C The following is a diagram showing an example of a configuration of a communication environment, a base station or a terminal for direction estimation according to various embodiments. Figure 5 and Figure 6 The operation of an apparatus for direction estimation according to various embodiments is described.

[0097] In order to explain the direction estimation of the present disclosure, the first device will be described with an example of estimating the direction of a signal to be transmitted from the first device to the second device. That is, the first device may be a transmitting device, and the second device may be a receiving device. The above-mentioned estimated communication direction is a direction for improving the communication quality between the first device and the second device, and may indicate AoD.

[0098] A grid of beams (GoB) scheme may be used as a method for estimating a transmission direction (e.g., AoD) or a reception direction (e.g., AoA) of a signal required for communication. According to the GoB scheme, a first device may identify a beam having the highest signal quality (e.g., reference signal received power (RSRP)) among a plurality of beams of the first device, and may determine a reference direction (e.g., a line of sight) of the identified beam as the AoD. In order to increase the accuracy of the angle estimated in the GoB scheme, that is, to increase the resolution of the estimated direction, a beam having a narrow beam width may be used. As the number of antennas of the first device used for beamforming increases, a beam having a narrower beam width may be generated. However, the narrower the beam width, the greater the number of beams including the same coverage, and thus the GoB scheme used to estimate the direction by exhaustively searching all beams may increase overhead due to beam training for many beams.

[0099] Unlike the GoB scheme that satisfies the resolution by simply operating a beam with a narrow beam width, a scheme using an auxiliary beam pair (ABP) to obtain high resolution can be considered. The first device can form multiple beams. The first device can perform beam training by using multiple beams. The first device can send a signal to a second device as a relative device by using each of the multiple beams, and can receive feedback about the sent signal from the second device. In the scheme using ABP, the direction (angle) is estimated by using a pair of beams, the pair of beams including a first beam with a maximum received power (e.g., RSRP) and a second beam with a greater received power among two beams adjacent to the first beam. The multiple beams preformed in the first device may include a first beam and a second beam. The first device can identify the first beam and the second beam among the multiple beams through beam training. The first device can estimate the communication direction of the two beams through the direction information of the two beams and the power information of the two beams. Unlike the GoB scheme that determines the reference direction of the beam with the maximum received power as the AoD, the first device can use the auxiliary beam pair to obtain a direction between the reference direction of the first beam and the reference direction of the second beam different from the first beam as the AoD. Therefore, compared with the GoB scheme that provides a fixed resolution according to the number of beams, the first device can estimate the direction of the signal more accurately. The above scheme can be called a GoB-based ABP scheme.

[0100] However, even the GoB-based ABP scheme may have an estimated error between the actual communication direction and the estimated communication direction. Although the direction of the actual signal is close to the reference direction of the first beam, a second beam adjacent to the first beam may be used, which may result in an error between the optimal direction of the actual signal and the estimated direction (hereinafter, the estimation error). This phenomenon is particularly prominent under high signal-to-noise ratios (SNRs). In order to reduce the above-mentioned estimation error, the present disclosure proposes a direction estimation scheme through two stages, the two stages being: identifying the beam through beam training, and then determining the communication direction by using an auxiliary beam pair that is symmetrical about the direction of the identified beam. The direction estimation scheme through two stages may be referred to as a two-stage direction estimation scheme, a two-stage angle estimation scheme, a two-stage beamforming-based direction estimation scheme, a two-stage beam training-based direction estimation scheme, a beam reconfiguration scheme, and the like.

[0101] Two-stage direction estimation scheme

[0102] Figure 5 The flowchart of the first device for direction estimation according to an embodiment of the present disclosure is shown. The first device may include a base station 110 or a terminal 120. The second device may include a base station 110 or a terminal 120.

[0103] refer to Figure 5 In operation 501, the first device may determine a beam set. The first device may determine a beam set for beam training. Beam training may mean a process in which a specific device (e.g., the base station 110) sequentially transmits a signal to an opposing device using different beam directions, thereby identifying a beam suitable for communicating with the opposing device (e.g., another terminal 120) among a plurality of beams in the beam set. The beam of the beam set according to various embodiments has a larger beam width than the beam of the auxiliary beam pair described below, and thus may be referred to as a wide beam set.

[0104] As the number of beams included in the beam set increases, the accuracy of locating the direction of the second device can be increased. This is because an increase in the number of beams used for beam training may increase the resolution of the direction. At the same time, the larger the number of beams used for beam training, the larger the number of signals sent for beam training, and thus the overhead for estimating the communication direction increases. On the contrary, if the number of beams included in the beam set decreases, the accuracy of the direction estimation may be reduced. This is because a reduction in the number of beams used for beam training may reduce the resolution of the direction. Similarly, the smaller the number of beams used for beam training, the smaller the number of signals sent for beam training, and thus the overhead for finding the communication direction is reduced. Therefore, considering both the improvement in accuracy and the overhead generated due to beam training, the first device is required to determine an appropriate beam set.

[0105] According to various embodiments, the first device may determine a beam set including a beam generated to have a specified beam width. The specified beam width means that the beam width of each beam of the beam set satisfies a specific condition. The specific condition may be related to the beam gap of the auxiliary beam pair. The specific condition may be designed to satisfy the periodicity of the phase to allow the vector of the auxiliary beam pair to be simplified, and then expressed when the auxiliary beam pair is used for angle estimation. The first device may determine the beam set based on the number of antennas of the antenna array. According to an embodiment, the beam width may be a half-power beam width (HPBW). The beam width may be defined as the angle between two directions having a radiation power intensity of half the maximum value in a cross section of a pattern including the radiation beam direction.

[0106] According to various embodiments, the first device may determine the beam width based on the beam gap between the beams of the auxiliary beam pair. The beam gap may mean the angle physically formed by the central direction of the beam. In order to configure the auxiliary beam pair with a specific angle, the first device may determine the beam width based on the specific angle. The reason for this determination is that the auxiliary beam pair is determined based on the reference beam.

[0107] According to various embodiments, the first device may determine the beam set based on the beam width and coverage to be provided by the first device. The coverage may include a directional range of a signal to be sent by beamforming. In a fixed coverage, the wider the beam width, the smaller the number of beams in the beam set. Conversely, in a fixed coverage, the narrower the beam width, the larger the number of beams in the beam set.

[0108] In operation 503, the first device may transmit a signal by using a beam set. The beam set may include a plurality of beams. The plurality of beams may indicate different directions respectively. The first device may transmit a signal by using each of the plurality of beams. The first device may repeatedly transmit a signal by sequentially using beams having different beam directions in the beam set. For example, the first device may perform beam scanning.

[0109] The signal may be a beamformed signal. According to various embodiments, the beamformed signal may include a synchronization signal. For example, the synchronization signal may be at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and an extended synchronization signal (ESS). In addition, for example, the synchronization signal may be an SS block. According to various embodiments, the beamformed signal may include a reference signal. For example, the reference signal may be at least one of a BRS, a beam refinement reference signal (BRRS), a cell-specific reference signal (CRC), a channel state information reference signal (CSI-RS), and a demodulation reference signal (DM-RS).

[0110] In operation 505, the first device may receive a signal indicating at least one beam. The first device may receive a signal indicating at least one beam among beams in the beam set from the second device. The second device may receive the signal transmitted in operation 503. The second device may receive the signal transmitted by using a different beam in operation 503, and may measure the received signal.

[0111] In the present disclosure, the metric used for signal measurement may be, for example, at least one of beam reference signal received power (BRSRP), RSRP, reference signal received quality (RSRQ), received signal strength indicator (RSSI), signal to interference and noise ratio (SINR), carrier to interference and noise ratio (CINR), SNR, error vector magnitude (EVM), bit error rate (BER), and block error rate (BLER). In addition to the described examples, other terms having the same technical meaning as the examples or other metrics indicating channel quality may also be used. In the present disclosure, high channel quality means high channel quality related to signal size, or low channel quality related to error rate. This may mean that as channel quality improves, a smooth wireless communication environment is ensured. In addition, the optimal beam may indicate the beam with the highest channel quality among the beams. Hereinafter, an example in which the channel quality determining the size of the beamforming signal is RSRP will be described.

[0112] Based on the measurement result, the second device may send a signal indicating at least one of the multiple beams to the first device. The second device may send a signal to the first device indicating the beam (or resource) corresponding to the signal measured as having the highest channel quality among the signals, that is, the beam providing the best channel state. For example, the second device may feed back a reference signal having the highest RSRP among the multiple reference signals to the first device.

[0113] The first device may determine a beam that is relatively suitable for communicating with the second device among multiple beams in the beam set by receiving a signal indicating at least one beam from the second device. In some embodiments, the second device may send feedback information including information indicating at least one beam to the first device. The feedback information may explicitly indicate at least one beam. For example, the feedback information may include resources of a CSI-RS. In some other embodiments, the first device may receive a specific signal indicating at least one beam on a resource region. The specific signal may implicitly indicate at least one beam. For example, the specific signal may include a random access preamble.

[0114] In operation 507, the first device may determine an auxiliary beam pair. In various embodiments, the auxiliary beam pair may mean a beam pair for accurately estimating the direction of a physical path of a signal (hereinafter, a communication direction) required for communication between a device (e.g., the first device) and an opposite device (e.g., the second device). Based on the channel quality (e.g., received power (RSRP)) of each of the two beams of the auxiliary beam pair, the first device may more accurately estimate the communication direction between the directions of the two beams.

[0115] The first device may identify a reference beam among the beams in the beam set. In order to determine the reference beam, the first device may obtain information related to at least one beam, which is received from the second device in operation 505. The first device may identify the reference beam among the at least one beam. According to various embodiments, at least one beam may be identified among the multiple beams in the beam set according to the channel quality. The first device may determine the beam with the highest channel quality among the multiple beams in the beam set. This is because the direction of the beam providing higher channel quality is similar to the communication direction. The first device may determine the beam corresponding to the highest channel quality as the reference beam.

[0116] The first device may determine the direction of the reference beam as a reference direction. The direction of the reference beam may mean the center direction of the reference beam. For example, the direction of the reference beam may be determined as a boresight direction, that is, a direction corresponding to a main lobe in a radiation pattern of an antenna forming the reference beam. The first device may determine two beams symmetrical about the reference direction as an auxiliary beam pair.

[0117] According to various embodiments, the first device may determine two beams corresponding to two directions symmetric about a reference direction as a beam pair. In other words, the two beams of the auxiliary beam pair may be symmetric about the center direction of the reference beam obtained by operations 503 to 505. The first device may reshape the beam to be symmetric about the reference direction instead of using the beam in the beam set. In other words, the auxiliary beam pair according to various embodiments may be different from the beam in the beam set. Each beam in the auxiliary beam pair may have a different visual axis direction from the visual axis direction of the beam in the beam set.

[0118] According to various embodiments, the first device may newly determine a beam set for determining an auxiliary beam pair based on the determined reference direction, instead of identifying a beam for the auxiliary beam pair among the beams in the beam set determined in operation 501. After that, the first device may determine the auxiliary beam pair from the beams in the newly determined beam set. The beam set of operation 501 may be referred to as a primary beam set. The beams of at least one auxiliary beam pair may be referred to as a secondary beam set. The process of transmitting a reference signal and receiving a received power of the reference signal as feedback may also be considered as an example of beam training, and thus the beams of at least one auxiliary beam pair may be referred to as a secondary beam set to distinguish from the beam set of operation 501.

[0119] According to various embodiments, the first device may determine beams that provide two directions symmetrical to each other among directions at a specified angle to a reference direction as an auxiliary beam pair. The auxiliary beam pair may be determined based on the beam width of the beam set determined in operation 501. When the beam set is determined, the beam gap of the auxiliary beam pair is considered to determine the beam width. Therefore, the first device may determine the auxiliary beam pair based on the beam width of the reference beam. According to an embodiment, the first device may determine the auxiliary beam pair so that the beam width of the reference beam is exactly the same as the beam gap of the auxiliary beam pair. According to another embodiment, the first device may determine the auxiliary beam pair so that the beam width of the reference beam is a multiple of the beam gap of the auxiliary beam pair. According to yet another embodiment, the first device may determine the auxiliary beam pair so that the beam gap of the auxiliary beam pair is a multiple of the beam width of the reference beam. That is, the first device may determine the auxiliary beam pair based on the angle between the reference direction and the direction of each beam symmetrical about the reference direction, rather than simply determining the auxiliary beam pair based on the beam symmetrical about the reference direction. Twice the angle may correspond to a beam gap between beams of the auxiliary beam pair. In other words, the first device may determine the auxiliary beam pair based on the specified beam gap. In some embodiments, the first device may specify the beam gap based on the number of antennas of the antenna array used to form the beams of the auxiliary beam pair.

[0120] In operation 509, the first device may send a reference signal by using an auxiliary beam pair. The auxiliary beam pair may include a beam pair of the first device. The beam pair may include two beams of the first device. Hereinafter, for ease of explanation, the two-stage direction estimation scheme of the present disclosure will be described by using a single auxiliary beam pair, but the present disclosure is not limited thereto. In order to perform the two-stage direction estimation scheme, multiple auxiliary beam pairs may be used.

[0121] The auxiliary beam pair may include a first beam of the first device and a second beam of the first device. The communication angle may be located between the first beam and the second beam. The first device may send a reference signal by using each of the first beam and the second beam to estimate the precise communication angle. The first device may send a first reference signal by using the first beam. The second device may send a second reference signal by using the second beam. Each of the reference signals used may be at least one of a BRS, a BRRS, a CRS, a CSI-RS, and a DM-RS.

[0122] According to various embodiments, the beam width of each beam of the auxiliary beam pair may be smaller than the beam width of each beam of the beam set determined in operation 501. That is, the beam width of the first beam or the second beam may be smaller than the beam width of each of the plurality of beams in the beam set. After beam training is performed through the beam set, the auxiliary beam pair may be used to perform more accurate angle estimation.

[0123] In operation 511, the first device may receive feedback information. The first device may receive feedback information related to the auxiliary beam pair. The first device may receive feedback information related to the first beam. The feedback information may include channel quality related to the first beam. For example, the feedback information may include a received power value of a first reference signal sent by using the first beam. According to an example, the feedback information may include the RSRP of the first reference signal. The first device may receive feedback information related to the second beam. The feedback information may include channel quality related to the second beam. For example, the feedback information may include a received power value of a second reference signal sent by using the second beam. According to an example, the feedback information may include the RSRP of the second reference signal.

[0124] The first device may obtain the channel quality related to the first beam and the channel quality related to the second beam by using various methods. In some embodiments, the feedback information related to the first beam and the feedback information related to the second beam may be fed back as a message through one-time signaling. In some other embodiments, the feedback information related to the first beam and the feedback information related to the second beam may be sent as independent signals respectively.

[0125] In operation 513, the first device may determine a direction. According to various embodiments, the first device may determine a communication direction based on directional information of a reference beam. Because the reference beam provides the highest channel quality among the beams in the beam set of operation 501, the direction of the reference beam among the beams in the beam set may have a minimum error compared to the communication direction. The first device may obtain directional information related to the reference direction. The directional information related to the reference direction may include an absolute directional vector of a physical signal path generated by the reference beam.

[0126] The first device may determine a direction based on the feedback information. The direction may correspond to an optimal angle for allowing the first device to communicate with the second device. The optimal angle may mean a communication direction that provides optimal communication quality. The communication direction may be related to a physical path of a signal for optimal communication between the first device and the second device. For example, the communication direction may mean an AoD (or AoA) of a signal of the first device, which is required for the first device to communicate smoothly with the second device. In the present disclosure, the determination of the communication direction may be expressed as an estimation of the communication direction, an estimation of the angle, a determination of the communication angle, and the like. The determined communication direction may be expressed based on a vector of an antenna array that forms a beam in that direction.

[0127] According to various embodiments, the first device may determine the communication direction based on the channel quality associated with the first reference signal (e.g., the first RSRP) and the channel quality associated with the second reference signal (e.g., the second RSRP). The communication direction for the second device may be positioned between the direction in which the first reference signal is transmitted and the direction in which the second reference signal is transmitted. The first device may determine the communication direction based on the directional information of the auxiliary beam pair and the channel quality information (e.g., the first RSRP and the second RSRP).

[0128] Despite Figure 5 Although not shown in the figure, the first device may perform beamforming communication with the second device based on the obtained communication direction. The first device may form at least one beam corresponding to the communication direction. The first device may send data to the second device by using the beam corresponding to the communication direction. The first device may improve the quality of beamforming communication with the second device by obtaining a more accurate communication direction (communication angle). In addition, the first device may reduce the overhead caused by beam training by identifying at least one beam among the beams used for beam training based on the obtained communication direction.

[0129] exist Figure 5 In the embodiment, the reference signal is described as an example of a signal transmitted by using an auxiliary beam pair, but the present disclosure is not limited thereto. According to an embodiment, a synchronization signal may be used instead of the reference signal, or a beamforming signal including data may be used for direction estimation using an auxiliary beam pair. According to an embodiment, a wide beam such as an SS / PBCH block may be used for a beam set, and a CSI-RS may be used for reference signal transmission through an auxiliary beam pair. A relatively narrow beam width may result in a small direction determination.

[0130] exist Figure 5, operations 501 to 513 are described sequentially, but according to an embodiment, some operations may be described together, or some operations may be omitted. That is, the embodiments in the present disclosure are not to be understood as being limited to the order / operations illustrated in the flowchart. According to an embodiment, beam information for determining an auxiliary beam pair may be obtained by another scheme (e.g., AoA estimation using an uplink reference signal (e.g., SRS), beam information used previously and historically, etc., beam information used for previous data transmission (e.g., SRS resource ID, CSI-RS resource ID, SS / PBCH block ID)) instead of operations 501 to 505.

[0131] Figure 6 An example of direction estimation according to an embodiment of the present disclosure is illustrated. Figure 6 Will Figure 5 The communication direction estimation process illustrated in FIG. 1 is illustrated as direction estimation, which uses beam sets and auxiliary beam pairs. Figure 6 The first device estimating the AoD as a transmitting device and the second device estimating the AoA as a receiving device are shown in the figure.

[0132] refer to Figure 6 , the first device and the second device may communicate with each other through the channel 601. The first device may send a signal to the second device through the channel 601. The second device may receive a signal from the first device through the channel 601.

[0133] The first device may include a transmit antenna array 610. The transmit antenna array 610 may form transmit beams 611, 612, 613, 614, 615, and 616 of a beam set. Figure 7 and Figure 8 Determination of the beam set is explained in detail. The first device may determine the transmission beam 613 among the beams of the transmission antenna array 610 as a reference beam. The transmission beam 613 may be identified during a beam training process with the second device. For example, the transmission beam 613 may provide the highest channel quality among the transmission beams 611, 612, 613, 614, 615, and 616.

[0134] The first device may determine an auxiliary beam pair (a first beam 621 and a second beam 623) from the transmission beam 613 as a reference beam. The visual axis direction of the transmission beam 613 may be determined as a reference direction 625. The first device may determine a beam pair symmetrical about the reference direction 625 as an auxiliary beam pair. For example, the first device may determine a first beam 621 and a second beam 623 as a beam pair of the auxiliary beam pair, the first beam 621 and the second beam 623 being located at opposite ends of an angle formed by the transmission beam 613. The reason for the determination is that the communication direction is located within the coverage range of the transmission beam 613, that is, the angle range provided by the beam width of the transmission beam 613.

[0135] The second device may include a receive antenna array 630. The receive antenna array 630 may form receive beams 631, 632, 633, 634, 635, and 636 of a beam set. The second device may determine a receive beam 633 among the beams of the receive antenna array 630 as a reference beam. For example, the receive beam 633 may be determined through a beam training process.

[0136] The beam formed by the antenna array can be expressed as a vector. That is, all transmit beams and receive beams can be configured by the array response vector. Therefore, the first beam 621 and the second beam 623 (that is, the beams of the auxiliary beam pair determined by the first device) can be expressed by the following equation 1.

[0137]

[0138]

[0139] a t (v-δ t ) indicates a first array response vector of the first beam 621 of the auxiliary beam pair, and a t (v+δ t ) indicates the second array vector of the second beam 623 of the auxiliary beam pair. The directions of the two beams configuring the auxiliary beam pair can be respectively represented by v-δ t and v+δ t v indicates the reference direction 625, i.e., the boresight direction of the reference beam 613. v may be indicated as the direction of the auxiliary beam pair. t Indicates the direction difference between each beam (first beam 621 or second beam 623) of the auxiliary beam pair and the reference direction 625. N indicates the number of antennas of the corresponding transmitting node. Subscript t means transmitting node. In the following, in all equations, subscript t means transmitting node (e.g., first device), and subscript r means receiving node (e.g., second device).

[0140] According to various embodiments, the first device can determine δ according to Equation 2 t The first device may determine a δ that satisfies a specific condition t , so as to improve the accuracy of direction estimation by auxiliary beam pairs and reduce the complexity described later. The specific conditions may be referred to as monotone characteristic conditions, monotone attribute conditions, monotone function conditions, etc. Fig. 9 and Fig.10 to explain the detailed description of the specific condition.

[0141]

[0142] δ tIndicates the direction difference between each beam (first beam 621 or second beam 623) of the auxiliary beam pair and the reference direction 625, and is expressed in radians. N indicates the number of antennas of the transmitting node. k can be a natural number. According to various embodiments, 2δ t It can be the beam spacing of the auxiliary beam pair.

[0143] The channel 601 as the wireless communication path between the first device and the second device may be a single path as a MIMO channel. The channel 601 through which the actual communication signal passes may be expressed as a MIMO single path by the following Equation 3.

[0144] H=αa r (ψ)a t (μ) *

[0145] ...Equation 3

[0146] Wherein H indicates a channel 601, and α indicates a channel gain. μ indicates a transmission direction 650 of a communication direction, that is, a transmission angle AoD, and ψ indicates a reception direction 660 of a communication direction, that is, a reception angle AoA. If there is no noise, a signal transmitted by using two beams of an auxiliary beam pair can be expressed by the following equation 4.

[0147]

[0148]

[0149] where y Δ indicates a first reference signal transmitted by using a first beam of the auxiliary beam pair, and y Σ Indicates a second reference signal transmitted by using a second beam of the auxiliary beam pair. r (ψ) indicates the received response vector according to the direction ψ.

[0150] According to various embodiments, if the transmission angle (e.g., AoD (μ)) corresponding to the transmission direction 650 is estimated, the first device may obtain information related to the reception angle (e.g., AoA (ψ)) corresponding to the reception direction 660 in advance. In some embodiments, the first device may obtain information related to the reception angle from the second device. For example, the second device may feed back information related to the reception angle to the first device. In some other embodiments, the information related to the reception angle may be predetermined. For example, the receiving terminal may receive a signal through a beam with a wide beam width (e.g., an omnidirectional beam), so that the information related to the reception angle may be predetermined.

[0151] The power of a signal transmitted by using beams of the auxiliary beam pair according to Equation 4, that is, the first beam 621 and the second beam 623 , may be expressed by the following Equation 5.

[0152]

[0153]

[0154] x Δ Indicates the received power of the first reference signal transmitted by using the first beam of the auxiliary beam pair. Σ Indicates received power of a second reference signal transmitted by using the second beam of the auxiliary beam pair.

[0155] The received power of each beam (the first beam 621 and the second beam 623) of the auxiliary beam pair can be calculated as shown in the following equation 7 by using a of equation 5: t (μ) is expressed with the expression of the vector illustrated in Equation 1 and the following Equation 6.

[0156]

[0157]

[0158]

[0159] According to various embodiments, if the beam gap satisfies Equation 2, Equation 7 may be expressed as the following Equation 8.

[0160]

[0161]

[0162] The first device may obtain a ratio metric by using the received power of the beam of the auxiliary beam pair. The ratio metric may be a metric for determining a difference between the reference direction 625 and the actual estimated transmission direction 650. The ratio metric may be expressed by the following Equation 9.

[0163]

[0164] ζ AoD Indicates a ratio measurement.

[0165] By using Equation 8, Equation 9 can be expressed as the following Equation 10.

[0166]

[0167] μ is AoD, and indicates a transmission direction 650. v indicates a reference beam direction, in other words, a reference direction 625. The first device may estimate a transmission direction 650 of a communication path according to Equation 10.

[0168] exist Figure 6 In the description, a scheme for estimating AoD (i.e., the transmission direction 650 of the communication path through the auxiliary beam pair) has been described, but the present disclosure is not limited thereto. The second device may estimate AoA (i.e., the reception direction 660 of the communication path through the auxiliary beam pair) by a similar scheme. According to an embodiment, the second device may obtain information related to the angle corresponding to the transmission direction 650 (e.g., information related to AoD (μ)) from the first device. The second device may estimate AoA as a reception angle based on information related to the transmission angle corresponding to the transmission direction 650 and information related to the reception power of the auxiliary beam pair of the first device. According to another embodiment, the second device may identify a reference reception beam by reception beam scanning and estimate AoA as a reception angle by using an auxiliary beam vector determined according to the direction of the reference reception beam.

[0169] Figure 6 The diagram illustrates an angle estimation scheme based on a single beam pair using an auxiliary beam pair. However, as described above, the direction estimation according to the present disclosure may be performed by using a plurality of auxiliary beam pairs.

[0170] Beam set determination

[0171] According to various embodiments, the process of forming a beam set for identifying a reference beam and the process of determining an auxiliary beam pair based on the reference beam and estimating an angle by using the auxiliary beam pair may also be understood as an embodiment. That is, the two-stage angle estimation scheme of the present disclosure may include an embodiment related to the criteria for determining the optimal beam set, that is, in addition to newly forming an auxiliary beam pair from one of the beams of the beam set, determining which beam set. In the following, Figure 7 and 8 An embodiment for determining a beam set is illustrated.

[0172] Figure 7 The flowchart of a first apparatus for determining a beam set according to an embodiment of the present disclosure is illustrated. Figure 7 yes Figure 5 part of operation 501, and Figure 7 The flowchart of the embodiment of the present invention can be understood by the first device or the elements of the first device. The first device may include a base station 110 or a terminal 120.

[0173] refer to Figure 7In operation 701, the first device may determine a coverage range. The coverage range may include a physical range of a communication direction in which the first device will perform transmission. For example, the first device may determine a coverage range that is 180 degrees (ie, For example, the first device may determine an area corresponding to 120 degrees (e.g., a range from -60 degrees to +60 degrees) as the coverage range. For another example, the first device may determine an area corresponding to 360 degrees (i.e., all directions) as the coverage range.

[0174] In operation 703, the first device may determine a beam width. The first device may determine a beam width for facilitating determination of an auxiliary beam pair. If the first device determines a beam of a beam set for beam training as an auxiliary beam pair, a direction of another beam is considered instead of the direction of the beam providing the maximum received power, and thus an error may occur compared to an actual direction. Therefore, the first device may determine a beam width for a beam set so as to easily determine an auxiliary beam pair from an optimal beam (i.e., a beam providing the highest communication quality).

[0175] According to various embodiments, the first device may determine the beam width based on a specified angle. The specified angle may be determined based on the number of antennas of the antenna array. In addition, the specified angle may be configured so that the ratio metric satisfies a monotonic property. The ratio metric may indicate a relationship between a direction and a power. For example, the first device may determine the beam width based on an angle defined according to equation 2. That is, the first device may determine the beam width based on a beam gap of the auxiliary beam pair.

[0176] According to various embodiments, the first device may determine a multiple of the beam gap of the auxiliary beam pair as the beam width. For example, the first device may determine the beam width of the beam set as 2mδ t (m = 1, 2, 3, ..). The gap between auxiliary beam pairs can be 2δ t δ t It can be determined by Equation 2. The beam gap can be determined based on the number of antennas in the antenna array of the first device. That is, the first device can determine the beam width based on the number of antennas in the antenna array.

[0177] In operation 705, the first device may determine a beam set. The first device may determine the beam set based on the coverage range and the beam gap. Within the fixed coverage range, the wider the beam width, the fewer the number of beams in the beam set. Similarly, the narrower the beam width, the greater the number of beams. The first device may determine a beam set, i.e., a beam set covering a directional range corresponding to the determined coverage range. For example, if the size of the directional range corresponding to the fixed coverage range is 180 degrees (i.e., π radians) (e.g., from -90 to +90), and the beam gap is 30 degrees (i.e., radians), the beam set may include six beams.

[0178] Figure 7 The illustration shows that the coverage is determined before the beam gap is determined, but the coverage may be configured after the beam gap is determined or the coverage may be predetermined. Figure 7 The order shown in the figure.

[0179] Figure 8 An example of a beam width according to an embodiment of the present disclosure is illustrated.

[0180] refer to Figure 8 , the relationship between the beam gap of the auxiliary beam pair and the beam width of the beam set will be described by distinguishing between two cases when determining the beam set for beam training, including: a case where the beam set is determined to have a beam width for the auxiliary beam pair, and a case where the beam set is determined to have a beam width that is not associated with the auxiliary beam pair. For each of the cases, a reference beam has been identified by the beam set.

[0181] refer to Figure 8 , the first device may determine the first beam 801 and the second beam 803 based on the reference beam 800. The first device may determine the beam in the opposite end direction of the reference beam 800 as the auxiliary beam pair. Since the actual communication direction is between the directions of the beams of the auxiliary beam pair, the first device may determine the beam corresponding to the opposite end direction of the reference beam 800 as the auxiliary beam pair. The beam width of the reference beam 800 may be 2δ t δ t It can be determined by Equation 2.

[0182] The first device may determine the third beam 851 and the fourth beam 853 based on the reference beam 850. The first device may determine beams in opposite end directions of the reference beam 850 as auxiliary beam pairs. The beam width of the reference beam 850 may be 2δ t '. However, δ can be determined differently from Equation 2 t '. Since the beam width does not satisfy the condition of equation 2, equation 8 showing the received power cannot be applied. Figure 6 The direction estimation using the auxiliary beam pair illustrated in FIG may not be easy to perform. Since the first device performs direction estimation according to Equation 6, if the direction estimation is performed only by using given parameters (e.g., the received power value of the beam of the auxiliary beam pair and the direction of the received beam), the accuracy may be reduced.

[0183] If the first beam 801 and the second beam 803 are used as an auxiliary beam pair, the first device can obtain higher direction estimation accuracy than using the third beam 851 and the fourth beam 853 as the auxiliary beam pair. 2δ as the beam width of the reference beam 800 can be calculated based on Equation 2. t Determined as The present disclosure provides Equation 8 simplified from Equation 7, and thus the first device can estimate the communication direction from given parameters (e.g., the received power value of the beam of the auxiliary beam pair, and the direction of the received beam). The simplification of Equation 8 results in a monotonic function between the received power and the direction estimate, and thus the first device can obtain a high-precision direction estimate. By forming a beam set with an appropriate beam width size, the performance of beam estimation using the auxiliary beam pair can be improved. Referring to Fig.13A and 13B Describe the specific performance.

[0184] Determination of auxiliary beam pairs

[0185] Fig. 9 FIG. 1 is a flowchart of a first device for determining an auxiliary beam pair according to an embodiment of the present disclosure. Fig. 9 yes Figure 5 as part of operation 507, and Fig. 9 The flowchart of the embodiment of the present invention can be understood by the first device or the elements of the first device. The first device may include a base station 110 or a terminal 120.

[0186] In operation 901, the first device may identify a reference beam. The first device may perform beam training by using a beam set of the first device. The beam set may include a plurality of beams. In other words, the first device may perform beam training by using a plurality of beams of the first device. For example, the first device may transmit a reference signal (or a synchronization signal) using each of a plurality of beams and obtain a measurement result of a channel quality, thereby identifying a beam providing the highest channel quality among the plurality of beams. The first device may determine the identified beam as a reference beam. According to various embodiments, the first device may identify a reference beam providing the highest channel quality among the beams in the beam set used for beam training.

[0187] In operation 903, the first device may identify a reference direction. The first device may identify the reference direction based on a reference beam. The first device may identify the center direction (e.g., the boresight direction) of the reference beam as the reference direction. The boresight direction may mean a direction that provides maximum radiation gain when radiated from an antenna. According to various embodiments, the first device may obtain information related to the boresight direction of the beams of the beam set. The information related to the direction may be configured by expressing an array response vector used in an antenna array during beamforming.

[0188] In operation 905, the first device may determine an auxiliary beam pair. The first device may determine two beams that are symmetric about a reference direction as the auxiliary beam pair. If the auxiliary beam pair includes a first beam and a second beam, the direction of the first beam and the direction of the second beam may have an axisymmetric relationship with respect to the reference direction. The auxiliary beam pair is designed for accurate direction estimation, and thus according to various embodiments, the beam width of each of the two beams of the auxiliary beam pair may be smaller than the beam width of each beam of the beam set.

[0189] The first device may determine that a communication direction for communicating with the second device is within a range (hereinafter, an angular range) corresponding to a beam width of a reference beam. According to various embodiments, the first device may determine an auxiliary beam pair including beams corresponding to opposite ends of the angular range so as to identify the communication direction by using the auxiliary beam pair.

[0190] According to various embodiments, if the beamwidth of the reference beam satisfies Multiples of (i.e., beam width is 2mδ t (m=1, 2, 3, ..)), then the angle between the beams of the auxiliary beam pair (hereinafter, the beam gap) can be (Right now In some embodiments, the first device may determine the beam width of the beam set to be 2mδ t (m=2, 3, ..). That is, the beam width may be m≠1. The first device may determine two beams corresponding to opposite ends of the reference beam as an auxiliary beam pair based on the direction of the reference beam. The beam gap of the auxiliary beam pair is 2mδ t , and the angle between the direction of each of the beams of the beam pair and the reference direction is mδ t The angle between the beam direction of the auxiliary beam pair and the reference direction can satisfy the equation k' is a natural number which is m times k, and thus δ' t Satisfies equation 2.

[0191] In some embodiments, the first device may determine an additional beam pair instead of two beams corresponding to opposite ends of the reference beam as an auxiliary beam pair. The beam gap of the additional auxiliary beam pair may satisfy Equation 2. The first device may estimate the direction more accurately by forming the auxiliary beam pair in a narrower angular range. The first device may estimate the direction by the auxiliary beam pair corresponding to the opposite end of the reference beam (hereinafter, the primary beam pair), and additionally determine the auxiliary beam pair (hereinafter, the secondary beam pair) in a narrower angular range. The secondary beam pair may have a beam gap that satisfies Equation 2. For example, the beam gap of the primary beam pair may be 4δ t , and the beam gap of the secondary beam pair can be 2δ t .

[0192] Fig.10 An example of an auxiliary beam pair according to an embodiment of the present disclosure is illustrated.

[0193] refer to Fig.10 , the relationship between the gap of the auxiliary beam pair and the accuracy (or complexity) of the direction estimation will be described.

[0194] refer to Fig.10 , the first device may form a first auxiliary beam pair 1001. The gap of the first auxiliary beam pair 1001 may be 2δ 1 (in N is the number of antennas, and k is a natural number). Since the gap of the first auxiliary beam pair 1001 satisfies So, replace Equation 7 with Simplified to And replace Equation 7 with Simplified to The periodicity of the trigonometric function is satisfied by specifying the gap, and thus simplification can be achieved. μ indicates a transmission direction of a communication direction, and v indicates a reference direction.

[0195] Can be as Figure 8 The received power is simplified as shown in . Because the expression for received power is simplified, the monotonicity of the ratio metric can be satisfied. In other words, because the gap of the first auxiliary beam pair 1001 satisfies Therefore, the radio metric of the first auxiliary beam pair 1001 may follow a monotonic function. Specifically, referring to Equation 9, In this case, v is determined as the direction of the reference beam, and δ 1 pass Determine, and thus AoD is a monotonically decreasing function of μ. Since the ratio metric ζ AoD is a monotonic function, so the first device can be obtained from ζ AoD Obtain μ. The first device can estimate μ through Equation 10.

[0196] The first device may form a second auxiliary beam pair 1003. The gap of the second auxiliary beam pair 1003 may be 2δ 2 (in, N is the number of antennas, and k is a natural number). The second auxiliary beam pair 1003 may have a beam gap greater than the beam gap satisfying the condition according to Equation 2. For a relatively wide beam gap, it is not possible to provide a method of simplifying Equation 7 to Equation 8. Therefore, there is a difference between an actual operation and Equation 8 corresponding to the received power, and thus an error occurs between an actual optimal communication direction and an estimated communication direction. Specifically, according to various embodiments, if the gap of the auxiliary beam pair does not satisfy the condition (Equation 2), performance may deteriorate at a low SNR. Referring to FIG. 13A to FIG. 14D Describe the specific performance.

[0197] The first device may form a third auxiliary beam pair 1005. The gap of the third auxiliary beam pair 1005 may be 2δ 3 (in, N is the number of antennas, and k is a natural number). The third auxiliary beam pair 1005 may have a beam gap that is smaller than the beam gap that satisfies the condition according to Equation 2. For a relatively narrow beam gap, it is not possible to provide a method of simplifying Equation 7 to Equation 8. Therefore, there is a difference between the actual operation and Equation 8 corresponding to the received power, and thus an error occurs between the actual optimal communication direction and the estimated communication direction. If the auxiliary beam pair is generated to have a relatively narrow beam gap, the monotonicity of the radio metric used for direction estimation may no longer be maintained. Therefore, if the first device performs direction estimation through the third auxiliary beam pair 1005, an estimation error convergence phenomenon (estimation error flat bottom) may be caused at a high SNR. In other words, because monotonicity is not maintained, the estimation error may not be reduced even if the SNR increases.

[0198] Reference Figures 5 to 10 , a two-stage direction estimation scheme of the present disclosure has been described. For example, according to the present disclosure, by using the beams of the beam set, finding the rough angle range of the communication direction through the optimal beam, and generating an auxiliary beam pair based on the optimal beam, the first device is enabled to estimate the angle with high resolution. After beam training is performed using the beams of the beam set, beam training using the beams of the auxiliary beam pair is additionally performed, so that the resolution can be increased with less overhead. According to the above aspects and effects, in the present disclosure, conditions for the beam gap of the auxiliary beam pair for improving the accuracy of direction estimation are predefined, and the beam width of the beam set is determined according to the defined conditions in consideration of the beam gap, so that the resolution of the direction estimation can be improved, and a small estimation error can be achieved with a smaller number of beams.

[0199] According to various embodiments, the first device may estimate the communication direction and then form a beam corresponding to the estimated communication direction. The first device may communicate with the second device through the formed beam. The first device may provide higher communication quality to the second device by forming a beam with a more accurate direction. This is because as the direction of the beam is consistent with the actual communication direction, the path loss within a determined power range is minimized.

[0200] Various embodiments may also be applied to terminal-to-terminal communication (e.g., V2X communication) as well as base station-to-terminal communication. Figures 11 to 12C , the two-stage angle estimation scheme of the present disclosure will be described by taking the example of vehicle-to-vehicle (V2V) communication.

[0201] Fig.11 An example of direction estimation in inter-vehicle communication according to an embodiment of the present disclosure is illustrated.

[0202] refer to Fig.11 , the first vehicle 1110 can perform beamforming communication with the second vehicle 1120. If the vehicles (for example, the first vehicle 1110 and the second vehicle 1120) are traveling on the road, each of the vehicles moves in real time. In order to maintain beamforming communication between vehicles, each of the vehicles may need to find an appropriate beam based on information related to the travel of each vehicle (hereinafter, side information). Therefore, each vehicle needs to obtain side information. The second vehicle 1120 that sends a signal to the first vehicle 1110 will be described. The embodiment will be described mainly with respect to the operation of the second vehicle 1120, but the corresponding features can also be applied to the first vehicle 1110 in the same manner.

[0203] The second vehicle 1120 may obtain side information. The side information may include at least one of vehicle speed, steering wheel information, flash information, inertial sensor information, etc. In some embodiments, the second vehicle 1120 may obtain the side information of the first vehicle 1110. The second vehicle 1120 may obtain the side information from the first vehicle 1110. In some other embodiments, the second vehicle 1120 may obtain the side information of the second vehicle 1120. The second vehicle 1120 may obtain the side information through an internal sensor of the second vehicle 1120, etc.

[0204] The second vehicle 1120 may determine the range of the communication direction of the second vehicle 1120 based on the side information. For example, when the second vehicle 1120 transmits a signal to the first vehicle 1110, the second vehicle 1120 may determine the range of the AoD of the second vehicle 1120. Similarly, the first vehicle 1110 may determine the range of the communication direction of the second vehicle 1120 based on the side information. For example, when the first vehicle 1110 receives a signal from the second vehicle 1120, the first vehicle 1110 may determine the range of the AoA of the first vehicle 1110.

[0205] The second vehicle 1120 can determine the coverage range by determining the range of the communication direction. The coverage range can be Figure 7 The second vehicle 1120 may transmit the beams corresponding to the directions in the coverage area to the specified beam width (eg, ) is determined as a beam set.

[0206] The second vehicle 1120 predetermines the range of the communication direction (transmission direction) by using the side information, so that the number of candidate beams of the beam set can be reduced. The rough position of the vehicle can be identified by the side information, so that the coverage range can be reduced. The reduction in coverage can reduce the number of beams of the beam set and the beam overhead during beam training. In other words, the second vehicle 1120 can determine the beam set more efficiently through the side information. In the same way, the first vehicle 1110 also predetermines the range of the communication direction (reception direction) by using the side information, so that the number of candidate beams of the beam set can be reduced.

[0207] The second vehicle 1120 may perform beam training by using a beam set according to a reduced coverage. The second vehicle 1120 may identify beam 1130 as a reference beam. The second vehicle 1120 may determine beam 1131 and beam 1132 symmetrical about the direction of beam 1130 as an auxiliary beam pair. The second vehicle 1120 may estimate the communication direction (e.g., AoD) for the first vehicle 1110 through the auxiliary beam pair. The beam width of beam 1130 may be greater than the beam widths of beams 1131 and 1132. Similarly, the first vehicle 1110 may perform beam training by using a beam set according to a reduced coverage. The first vehicle 1110 may determine beam 1141 and beam 1142 symmetrical about the direction of beam 1140 as an auxiliary beam pair. The first vehicle 1110 may estimate the communication direction (e.g., AoA) for the second vehicle 1120 through the auxiliary beam pair.

[0208] Fig. 12AAn example of direction tracking in inter-vehicle communication according to an embodiment of the present disclosure is illustrated. The operation of determining the communication direction within the determined beam width of the reference beam may be referred to as direction tracking.

[0209] refer to Fig. 12A , the time domain behavior of the vehicle for direction tracking will be described. The direction tracking as described above includes direction estimation according to a two-stage angle estimation scheme, which is based on a reference Figures 5 to 10 Various embodiments described. A vehicle may determine a communication direction with respect to a coverage area of ​​a reference beam by using a beam of an auxiliary beam pair in relation to the reference beam.

[0210] refer to Fig. 12A , the second vehicle 1120 may perform periodic direction estimation 1210. The second vehicle 1120 may perform direction estimation with the first vehicle 1110 periodically.

[0211] Referring to the periodic time stream 1215, the second vehicle 1120 may perform channel estimation during a period 1221. Through the channel estimation, the second vehicle 1120 may identify a reference beam and determine a reference direction. During a period 1222, the second vehicle 1120 may send data to the first vehicle 1110 through a data channel (e.g., a dedicated data channel (DDC)). The period 1222 may be referred to as a data period. The second vehicle 1120 may perform a transition during a period 1223. Transition means that the communication channel transitions from a data channel to a tracking channel (e.g., a dedicated tracking channel (DTC)). The period 1223 may be referred to as a transition period (TP). The second vehicle 1120 may determine a communication direction, i.e., a direction for communicating with the first vehicle 1110 through a tracking channel during a period 1224. The second vehicle 1120 may determine the communication direction by directional tracking within the coverage of the reference direction. By determining an auxiliary beam pair according to the present disclosure, the second vehicle 1120 may determine a communication direction for the first vehicle 1110. The period 1224 may be referred to as a tracking period.

[0212] After the tracking period, the second vehicle 1120 may change the communication channel from the tracking channel to the data channel during the transition period. During the period 1225, the second vehicle 1120 may send data to the first vehicle 1110 again through the data channel. The second vehicle 1120 changes the communication channel to the tracking channel through the transition period, then determines the communication direction with the first vehicle 1110, and changes the communication channel to the data channel again through the transition period. During the period 1226, the second vehicle 1120 may send data to the first vehicle 1110 again through the data channel. In the same period (transition period → tracking period → transition period), the second vehicle 1120 may send data to the first vehicle 1110 again through the data channel during the period 1227. Periodically, the transition period, the tracking period, the transition period, and the data period are repeated, whereby the second vehicle 1120 may periodically track the direction of the first vehicle 1110. In addition, the second vehicle 1120 may periodically send data to the first vehicle 1110. When the next channel estimation period arrives, the second vehicle 1120 may identify the reference beam again and periodically perform direction tracking again.

[0213] The second vehicle 1120 may perform aperiodic direction estimation 1260. A trigger condition for performing the aperiodic direction estimation 1260 may be defined differently.

[0214] In some embodiments, when the movement range of the second vehicle 1120 exceeds a threshold range, the second vehicle 1120 may trigger the non-periodic direction estimation 1260. For example, the second vehicle 1120 may determine whether the movement range of the second vehicle 1120 exceeds the threshold range, and the determination is performed based on the movement range of the steering wheel of the second vehicle and the speed of the vehicle. If the movement speed of the second vehicle 1120 is greater than or equal to the threshold speed, and the movement angle of the steering wheel exceeds the threshold angle, the second vehicle 1120 determines that the movement range exceeds the threshold range. The second vehicle 1120 may start the non-periodic direction estimation 1260.

[0215] In some other embodiments, the second vehicle 1120 may trigger the non-periodic direction estimation 1260 of the second vehicle 1120 based on the GPS information and the flash light information. For example, the second vehicle 1120 may recognize that the second vehicle has moved in a direction different from the existing direction of travel, the recognition being performed based on the location information such as a three-way or four-way intersection and the left flash light information. The second vehicle 1120 may start the non-periodic direction estimation 1260.

[0216] In some other embodiments, the second vehicle 1120 may trigger the aperiodic direction estimation 1260 based on the channel quality of the beam currently being used. For example, when the channel quality (e.g., RSRP) of the serving beam rapidly deteriorates, the second vehicle 1120 may declare a link disconnection (e.g., BLF) and determine that direction tracking is required. The second vehicle 1120 may start the aperiodic direction estimation 1260.

[0217] Referring to the non-periodic time stream 1265, the second vehicle 1120 may perform channel estimation during a period 1271. During a period 1272, the second vehicle 1120 may transmit data to the first vehicle 1110 through a data channel. The second vehicle 1120 may perform a transition of a communication channel from a data channel to a tracking channel during a period 1273. The second vehicle 1120 may determine a communication direction, i.e., a direction for communicating with the first vehicle 1110 through the tracking channel, during a period 1274. The second vehicle 1120 may determine a communication direction for the first vehicle 1110 within a beam width of a reference beam. After the period 1274, the second vehicle 1120 may undergo a transition period, and then transmit data to the first vehicle 1110 through the data channel again during a period 1275.

[0218] If aperiodic direction estimation is triggered in the process of periodically performing direction tracking and data transmission, the second vehicle 1120 may perform direction tracking and then transmit data to the first vehicle 1110 in a random period. After the second vehicle 1120 performs direction tracking, the second vehicle 1120 may transmit data to the first vehicle 1110 during a period 1276. After the second vehicle 1120 aperiodically performs direction tracking, the second vehicle 1120 may transmit data to the first vehicle 1110 during a relatively long period of time. After the second vehicle 1120 performs direction tracking, the second vehicle 1120 may transmit data to the first vehicle 1110 during a period 1277. After the second vehicle 1120 aperiodically performs direction tracking, the second vehicle 1120 may transmit data to the first vehicle 1110 during a relatively short period of time. The second vehicle 1120 may obtain a communication direction by manually triggering direction tracking according to a situation in which direction tracking is required, when necessary, and may improve communication efficiency by flexibly adjusting the data period as needed.

[0219] Fig. 12B The diagram shows an example of performing direction tracking by changing the traveling direction in inter-vehicle communication according to an embodiment of the present disclosure. The direction tracking as described above includes referring to Figures 5 to 10 Determination of auxiliary beam pairs described. Fig. 12B An example of determining the number of auxiliary beam pairs according to a change in the traveling direction of the vehicle is illustrated.

[0220] refer to Fig. 12B In the first example 1220, the second vehicle 1120 may change the direction of travel by a first angle 1228 (θ 1 ). The second vehicle 1120 may determine a direction range corresponding to the first angle 1228. The second vehicle 1120 may determine the number of auxiliary beam pairs according to the determined direction range. For example, when the first angle 1228 does not exceed the threshold range, the second vehicle 1120 may determine the auxiliary beam pair. The second vehicle 1120 may determine the beam corresponding to the opposite end of the beam width of the reference beam as the auxiliary beam pair. For example, both the beam width of each beam of the beam set of the second vehicle 1120 and the gap of the auxiliary beam pair may be

[0221] In the second example 1270, the second vehicle 1120 may change the direction of travel by a second angle 1278 (θ 2 ). The second vehicle 1120 may determine a direction range corresponding to the second angle 1278. The second vehicle 1120 may determine the number of auxiliary beam pairs based on the determined direction range. For example, when the second angle 1278 exceeds a threshold range, the second vehicle 1120 may determine two or more auxiliary beam pairs. In other words, the second vehicle 1120 may determine an auxiliary beam pair that is obtained by pairing beams corresponding to opposite ends of the beam width of the reference beam not only but also by pairing the beams that are symmetrical about the reference direction of the reference beam and spaced apart from each other by a predetermined angle (e.g., ) is formed by pairing with other beams of the second vehicle 1120. For example, the beam width of each beam of the beam set of the second vehicle 1120 may be For example, the beam spacing of the first auxiliary beam pair may be And the beam spacing of the second auxiliary beam pair can be Both beam gaps of the auxiliary beam pair satisfy the condition of Equation 2.

[0222] Fig. 12B The embodiment of two cases according to whether the change angle of the traveling direction exceeds the threshold range is illustrated, but the present disclosure is not limited thereto. According to various embodiments, the number of levels according to the change angle when the traveling direction changes may be defined as K (K is a natural number equal to or greater than 3), and the number of auxiliary beam pairs corresponding to each level may be defined. The second vehicle 1120 may estimate the direction for the first vehicle 1110 by operating three or more auxiliary beam pairs.

[0223] Fig. 12CThe diagram shows an example of performing direction estimation by changing the reference direction in inter-vehicle communication according to an embodiment of the present disclosure. The direction estimation as described above includes direction estimation according to a two-stage angle estimation scheme, which is based on the reference direction. Figures 5 to 10 Various embodiments described herein. Fig. 12C , the direction estimation process by tracking the reference beam will be described.

[0224] refer to Fig. 12C , the second vehicle 1120 may track the reference beam. According to the tracking result, the second vehicle 1120 may determine whether to maintain the first reference beam 1235 as the reference beam for determining the auxiliary beam pair. In the first example 1230, the second vehicle 1120 may maintain the reference beam as the first reference beam 1235. In contrast, in the second example 1280, the second vehicle 1120 may change the reference beam to the second reference beam 1285.

[0225] According to various embodiments, the second vehicle 1120 may periodically determine whether to maintain the first reference beam 1235 as a reference beam for determining the auxiliary beam pair. In some embodiments, the second vehicle 1120 may periodically determine whether the direction of travel has changed without exceeding a threshold range. The threshold range may be configured for the direction in which the reference beam needs to be changed. According to an embodiment, the threshold range may be determined based on the beam width of each beam of the beam set. For example, the threshold range may be configured to have an angle greater than the beam width. The second vehicle 1120 may identify the first reference beam 1235 among the beams in the beam set. The second vehicle 1120 may determine the communication direction for the first vehicle 1110 by using the auxiliary beam pair corresponding to the first reference beam 1235. The second vehicle 1120 may communicate with the first vehicle 1110 through the determined communication direction.

[0226] In some other embodiments, the second vehicle 1120 may periodically measure the channel quality related to the first reference beam 1235. According to the degree of change in the channel quality, the second vehicle 1120 may determine whether to maintain the first reference beam 1235 as a reference beam for determining the auxiliary beam pair. In some other embodiments, the second vehicle 1120 may periodically receive channel information from the first vehicle 1110. According to parameters (e.g., channel quality indicator (CQI) and CSI-RS resource indicator (CRI)) included in the channel information (e.g., CSI), the second vehicle 1120 may determine whether to maintain the first reference beam 1235 as a reference beam for determining the auxiliary beam pair.

[0227] In some other embodiments, the second vehicle 1120 may periodically obtain side information of the second vehicle 1120. Based on speed information, rotation information (e.g., steering wheel rotation information), and sensor information (e.g., inertial sensor) included in the side information, the second vehicle 1120 may determine whether to maintain the first reference beam 1235 as a reference beam for determining the auxiliary beam pair.

[0228] The second vehicle 1120 may aperiodically determine whether to maintain the first reference beam 1235 as a reference beam for determining the auxiliary beam pair. The second vehicle 1120 may detect a predetermined trigger condition to determine a change in the reference beam. For example, when a signal requiring a beam change is received from the first vehicle 1110, the second vehicle 1120 may determine whether to maintain the reference beam. The second vehicle 1120 may determine whether to change the reference beam through beam training.

[0229] If the change of the reference beam is determined, the second vehicle 1120 may identify the second reference beam 1285. The second vehicle 1120 may manually perform beam training. The second vehicle 1120 may perform beam training by transmitting a signal using each of the beams of the beam set. According to an embodiment, the second vehicle 1120 may reduce the number of candidate beams of the beam set based on the side information, such as Fig.11 The second vehicle 1120 may identify the second reference beam 1285 as a new reference beam. The second vehicle 1120 may determine a communication direction for the first vehicle 1110 by using an auxiliary beam pair corresponding to the second reference beam 1285. The second vehicle 1120 may communicate with the first vehicle 1110 through the determined communication direction.

[0230] Fig.13A FIGURES illustrate a graph showing the performance of beamwidth according to an embodiment of the present disclosure.

[0231] Fig. 13B FIG. 2 is a graph illustrating the performance of a beam width according to an embodiment of the present disclosure. According to various embodiments of the present disclosure, the beam width may be an angle determined based on a monotonic characteristic condition.

[0232] refer to Fig.13A , a graph 1300 shows the performance difference between a beam set satisfying the monotonic characteristic condition and a beam set not satisfying the condition when each of the number of antennas of the transmitting antenna array and the number of antennas of the receiving antenna array is 8. The horizontal axis 1301 shows the SNR (dB), and the vertical axis 1302 shows the average error (hereinafter, the estimation error) (°) regarding the angle estimation. It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1310 shows the performance difference between the beam set satisfying the monotonic characteristic condition (i.e., Equation 2) by using a beam width having a value satisfying the monotonic characteristic condition (i.e., Equation 2). The second line 1315 shows the performance of the direction estimation using the auxiliary beam pair after identifying the reference beam by using the beam set having a beam width that does not satisfy the monotonic characteristic condition. The performance of the direction estimation using auxiliary beam pairs after the beam set identification reference beam.

[0233] As shown in the graph 1300, it can be noted that as the SNR increases, the difference in estimated error between the beam set satisfying the monotonic characteristic condition and the beam set not satisfying the condition gradually increases. By increasing the difference in estimated error relative to the SNR equal to or greater than the reference value, it can be identified whether direction estimation using the beam set satisfying the monotonic characteristic condition of the present disclosure has been performed.

[0234] refer to Fig. 13B , a curve graph 1320 shows the performance difference between a beam set that satisfies the monotonic characteristic condition and a beam set that does not satisfy the condition when the number of antennas of the transmitting antenna array is 16 and the number of antennas of the receiving antenna array is 8. The horizontal axis 1321 shows the SNR (dB), and the vertical axis 1322 shows the estimation error (°). It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1330 shows the performance difference between the beam set that satisfies the monotonic characteristic condition (i.e., Equation 2) by using a beam width that satisfies the monotonic characteristic condition (i.e., Equation 2). The performance of the direction estimation using the auxiliary beam pair after identifying the reference beam by using the beam set of The performance of the direction estimation using auxiliary beam pairs after the beam set identification reference beam.

[0235] As shown in the graph 1320, it can be noted that as the SNR increases, the estimation errors of the beam set satisfying the monotonic characteristic condition and the beam set not satisfying the condition both decrease, but a smaller estimation error is obtained by using the direction estimation of the beam set satisfying the monotonic characteristic condition. By changing the estimation error according to whether the monotonic characteristic condition is satisfied, it can be identified whether the present disclosure has been performed.

[0236] Fig.14A FIGURES illustrate graphs showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure.

[0237] Fig. 14B FIGURES illustrate graphs showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure.

[0238] Fig. 14C FIGURES illustrate graphs showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure.

[0239] Fig.14D FIGURES illustrate graphs showing the performance of direction estimation through a two-stage angle estimation scheme according to an embodiment of the present disclosure.

[0240] refer to Fig.14A , a graph 1400 shows the performance difference between the direction estimation scheme using the auxiliary beam pair and the beam set satisfying the monotonic characteristic condition and the GoB scheme when each of the number of antennas of the transmitting antenna array and the number of antennas of the receiving antenna array is 8. The horizontal axis 1401 shows the SNR (dB), and the vertical axis 1402 shows the estimation error (°). It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1410 shows the performance difference between the direction estimation scheme using the auxiliary beam pair and the beam set satisfying the monotonic characteristic condition (i.e., Equation 2) by using the beam width The second line 1415 shows the performance of the GoB scheme in which a specific beam is identified by using a plurality of beams and then the boresight direction of the specific beam is determined as the communication direction.

[0241] According to the scheme of the first line 1410, that is, the two-stage angle estimation scheme according to various embodiments uses a total of eight beams. The beam set may include a total of six beams. Two beams corresponding to opposite ends of the reference beam among the six beams can be used as auxiliary beam pairs. Therefore, for the two-stage angle estimation scheme, signaling for a total of eight beams (e.g., transmission of a reference signal for beamforming and feedback of the signal) is used. In the GoB scheme, that is, according to the scheme of the second line 1415, beam training is performed through eight beams, and the second line 1415 shows the resulting performance.

[0242] As shown in graph 1400, it can be noted that as the SNR increases, the performance of the two-stage angle estimation scheme increases compared to the GoB scheme. It can be noted that when using the same number of beams as the GoB scheme, the two-stage angle estimation scheme can provide an estimation error that is smaller than that of the GoB scheme.

[0243] refer to Fig. 14B , a curve graph 1420 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition and the GoB scheme when the number of antennas of the transmitting antenna array is 16 and the number of antennas of the receiving antenna array is 8. The horizontal axis 1421 shows the SNR (dB), and the vertical axis 1422 shows the estimation error (°). It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1430 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition (i.e., Equation 2) and the GoB scheme. The second line 1435 shows the performance of the GoB scheme that uses a plurality of beams to identify a specific beam and then determines the boresight direction of the specific beam as the communication direction.

[0244] According to the scheme of the first line 1430, that is, the two-stage angle estimation scheme according to various embodiments, a total of nine beams are used. The beam set may include a total of seven beams. Two beams corresponding to opposite ends of the reference beam among the seven beams may be used as auxiliary beam pairs. Therefore, for the two-stage angle estimation scheme, signaling for a total of nine beams (e.g., transmission of a reference signal for beamforming and feedback of the signal) is used. In the GoB scheme, that is, in the scheme according to the second line 1435, beam training is performed by 16 beams and the second line 1435 shows the resulting performance.

[0245] As shown in the graph 1420, it can be noted that as the SNR increases, the performance of the two-stage angle estimation scheme increases compared to the GoB scheme. In addition, it can be noted that because the two-stage angle estimation scheme uses a beam whose number (9) is smaller than the number of beams (16) used for the GoB scheme, the overhead is reduced and the estimation error of the two-stage angle estimation scheme is smaller than the estimation error of the GoB scheme.

[0246] refer to Fig. 14C , a curve graph 1440 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition and the GoB-based direction estimation scheme using auxiliary beam pairs when each of the number of antennas of the transmitting antenna array and the number of antennas of the receiving antenna array is 8. The horizontal axis 1441 shows the SNR (dB), and the vertical axis 1442 shows the estimation error (°). It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1450 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition (i.e., Equation 2) and the GoB-based direction estimation scheme using auxiliary beam pairs. The second line 1455 shows the performance of the scheme of identifying the optimal beam by using a plurality of beams and then determining the beam with the highest channel quality among the optimal beam and beams adjacent to the optimal beam as the auxiliary beam pair to determine the communication direction.

[0247] According to the scheme of the first line 1450, that is, the two-stage angle estimation scheme according to various embodiments, a total of eight beams are used. The beam set may include a total of six beams. Two beams corresponding to opposite ends of the reference beam among the six beams may be used as auxiliary beam pairs. Therefore, for the two-stage angle estimation scheme, signaling for a total of eight beams (e.g., transmission of a reference signal for beamforming and feedback of the signal) is used. In the GoB-based auxiliary beam pair scheme, that is, in the scheme according to the second line 1455, beam training is performed through eight beams, and the second line 1455 shows the resulting performance.

[0248] refer to Fig.14D , a curve graph 1460 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition and the GoB-based direction estimation scheme using auxiliary beam pairs when the number of antennas of the transmitting antenna array is 16 and the number of antennas of the receiving antenna array is 8. The horizontal axis 1461 shows the SNR (dB), and the vertical axis 1462 shows the estimation error (°). It is assumed that the actual communication direction has a random value in the range of [-60°, 60°]. The first line 1470 shows the performance difference between the direction estimation scheme using auxiliary beam pairs and beam sets satisfying the monotonic characteristic condition (i.e., Equation 2) and the GoB-based direction estimation scheme using auxiliary beam pairs. The second line 1475 shows the performance of the scheme of identifying the optimal beam by using a plurality of beams and then determining the beam with the highest channel quality among the optimal beam and beams adjacent to the optimal beam as the auxiliary beam pair to determine the communication direction.

[0249] According to the scheme of the first line 1470, that is, the two-stage angle estimation scheme according to various embodiments, a total of nine beams are used. The beam set may include a total of seven beams. Two beams corresponding to opposite ends of the reference beam among the seven beams may be used as auxiliary beam pairs. Therefore, for the two-stage angle estimation scheme, signaling for a total of nine beams (e.g., transmission of a reference signal for beamforming and feedback of the signal) is used. In the GoB-based auxiliary beam pair scheme, that is, in the scheme according to the second line 1475, beam training is performed by 16 beams, and the second line 1475 shows the resulting performance.

[0250] Graphs 1440 and 1460 are similar to graphs 1400 and 1420. However, communication direction estimation using the GoB-based auxiliary beam pair scheme provides an estimation error that is smaller than the estimation error of communication direction estimation using only the GoB scheme. Referring to graphs 1440 and 1460, it can be noted that if it is ensured that the SNR is greater than or equal to a predetermined level, it is possible to estimate the communication direction with high resolution.

[0251] As shown in the graph 1440, it can be noted that as the SNR increases, the performance of the two-stage angle estimation scheme increases compared to the GoB-based auxiliary beam pair scheme. It can be noted that when using the same number of beams as the GoB-based auxiliary beam pair scheme, the two-stage angle estimation scheme can provide an estimation error that is smaller than that of the GoB-based auxiliary beam pair scheme.

[0252] As shown in the graph 1460, it can be noted that as the SNR increases, the performance of the two-stage angle estimation scheme improves compared to the GoB-based auxiliary beam pair scheme. In addition, it can be noted that because a number of beams (9) less than the number of beams (16) used for the GoB-based auxiliary beam pair scheme is used by the two-stage angle estimation scheme, the overhead is reduced and the estimation error of the two-stage angle estimation scheme is smaller than that of the GoB scheme.

[0253] The two-stage direction estimation scheme of the present disclosure includes: a first stage of identifying the optimal beam by beam training of a beam set by a device, and a second stage of estimating the communication direction by using an auxiliary beam pair determined by the identified beam. The present disclosure has been described so that the beam training process as the first stage or the direction estimation process as the second stage includes the transmission of a beamformed signal and the feedback of the signal, but the implementation scope of the present disclosure is not limited to this. In an environment where channel reciprocity is satisfied (e.g., time division duplex (TDD)), direction estimation without feedback can be performed. For example, Figure 1 The base station 110 may perform reception beam scanning through a signal transmitted by the terminal 120, and determine an auxiliary beam pair from the optimal reception beam. For another example, the base station 110 may determine an auxiliary beam pair for determining AoA from the optimal transmission beam among the beams of the base station.

[0254] In the present disclosure, although the expression "equal to or greater than" or "equal to or less than" is used in order to determine whether a specific condition is satisfied, this is only an example, and the expression "greater than" or "less than" is not excluded. The expression "equal to or greater than" may be replaced with "greater than", the expression "equal to or less than" may be replaced with "less than", and the expression "equal to or greater than and less than" may be replaced with "greater than, equal to, or less than" under the above conditions.

[0255] The methods according to the embodiments described in the claims and / or the specification of the present disclosure may be implemented in hardware, software, or a combination of hardware and software.

[0256] When the method is implemented by software, a computer-readable storage medium for storing at least one program (software module) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors in an electronic device. At least one program may include instructions that cause an electronic device to perform a method according to the embodiments as defined in the appended claims and / or disclosed herein.

[0257] The program (software module or software) may be stored in a non-volatile memory including random access memory and flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk storage device, a compact disk-ROM (CD-ROM), a digital versatile disk (DVD) or other type of optical storage device or a cassette tape. Alternatively, any combination of some or all of them may form the memory in which the program is stored. In addition, a plurality of separate memories may be included.

[0258] In addition, the program can be stored in a connectable storage device that can be accessed through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), and a storage area network (SAN) or a combination thereof. Such a storage device can access the apparatus for performing the embodiment via an external port. In addition, a separate storage device on a communication network can access the apparatus for performing the embodiment.

[0259] In the above detailed embodiments, according to the above detailed embodiments, the elements included in the present disclosure are expressed in the singular or plural. However, for ease of description, the singular form or plural form is selected to be suitable for a given situation, and the present disclosure is not limited to a single element or its multiple elements. In addition, multiple elements expressed in the specification can be configured as a single element, or a single element in the specification can be configured as multiple elements.

[0260] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a first device including an antenna array in a wireless communication system, the method comprising: The signal is transmitted by using a beam set; receiving a signal indicating at least one beam in the set of beams from a second device; identifying a reference beam among a plurality of beams in the beam set; Identifying a center direction of a reference beam as a reference direction based on the signal indicating at least one beam; determining an auxiliary beam pair, wherein the auxiliary beam pair comprises a first beam and a second beam that are symmetric about the reference direction; transmitting a reference signal to the second device by using an auxiliary beam pair; receiving feedback information related to the auxiliary beam pair from the second device; and determining a communication direction related to the second device based on the feedback information, The angle between the reference direction and each of the direction of the first beam and the direction of the second beam is determined based on the number of antennas of the antenna array.

2. The method according to claim 1, in, The direction of the first beam and the direction of the second beam are determined based on an angle between the reference direction and each of the direction of the first beam and the direction of the second beam.

3. The method according to claim 2, wherein: The angle is determined according to 2kπ / N, N is the number of the antennas of the antenna array, and k is an integer greater than or equal to 1.

4. The method according to claim 1, further comprising: Determine coverage; determining a beam width based on the coverage area and the number of beams; as well as The beam set is determined based on the beamwidth.

5. The method according to claim 4, wherein: The beam width is determined based on the number of antennas of the antenna array.

6. The method according to claim 5, wherein: The beam width is determined as a multiple of 2kπ / N, N is the number of the antennas of the antenna array, k is an integer greater than or equal to 1, and the angle between the directions of the beams of the auxiliary beam pair is 2kπ / N.

7. The method according to claim 1, wherein: The feedback information includes information about a channel quality of a first reference signal transmitted by using the first beam of the auxiliary beam pair, and information about a channel quality of a second reference signal transmitted by using the second beam of the auxiliary beam pair.

8. The method according to claim 7, wherein: The determining the communication direction includes determining the communication direction based on the reference direction of the reference beam, the channel quality of the first reference signal, and the channel quality of the second reference signal.

9. The method according to claim 1, in, The auxiliary beam pair includes two beams corresponding to opposite end directions of the reference beam, and The beam width of the reference beam is determined based on a multiple of 2kπ / N, N is the number of antennas of the antenna array configured to form the auxiliary beam pair, and k is an integer greater than or equal to 1.

10. The method according to claim 9, further comprising: Determine additional auxiliary beam pairs, The angle between the directions of the beams of the additional auxiliary beam pair is 2kπ / N.

11. The method according to claim 1, further comprising: Data is transmitted to the second device by using a beam corresponding to the communication direction.

12. A first device in a wireless communication system, the device comprising: Antenna arrays; at least one transceiver; and at least one processor, The at least one processor is configured to execute one of methods 1 to 11.

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