Communication device, method, and non-transitory computer-readable storage medium for calibration

Abstract

This communication device including a plurality of radio frequency (RF) processing circuits for an antenna array is configured to: transmit first calibration signals having a first subcarrier spacing (SCS) through a plurality of RF transmission paths of the plurality of RF processing circuits; obtain the first calibration signals through a plurality of RF reception paths of the plurality of RF processing circuits; identify a bandwidth of a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value, on the basis of amplitude information and phase information of the first calibration signals; and perform calibration by transmitting second calibration signals on orthogonal frequency division multiplexing (OFDM) symbols according to a second SCS corresponding to the bandwidth of the frequency domain from among a plurality of SCSs, wherein the second SCS indicates a frequency interval of each of the OFDM symbols, and a time interval of each of the OFDM symbols is inversely proportional to the second SCS.

Description

Communication device, method, and non-transitory computer-readable storage medium for calibration

[0001] The following descriptions relate to a communication device, method, and non-transitory computer-readable storage medium for calibration.

[0002] As base station signals pass through RF (radio frequency) processing circuits, their amplitude and phase may change depending on the hardware characteristics of the RF processing circuits. To correct the amplitude and phase of base station signals, the base station can perform calibration.

[0003] The above information may be provided as background art to aid in understanding the present disclosure. No claim or determination is made as to whether any of the above is applicable as prior art related to the present disclosure.

[0004] A communication device is provided. The communication device may include an antenna array. The communication device may include a plurality of radio frequency (RF) processing circuits for the antenna array. The communication device may include a memory storing instructions and including one or more storage media. The communication device may include at least one processor including a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to transmit first calibration signals having a first subcarrier spacing (SCS) through a plurality of RF transmit paths of the plurality of RF processing circuits. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to obtain the first calibration signals through a plurality of RF receive paths of the plurality of RF processing circuits. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to identify a bandwidth in a frequency domain having an amplitude variation of the first calibration signals that is less than a first threshold value and a phase variation of the first calibration signals that is less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to perform calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among a plurality of SCSs. The second SCS may indicate a frequency interval of each of the OFDM symbols.The time interval of each of the above OFDM symbols may be inversely proportional to the second SCS.

[0005] A method is provided for a communication device including a plurality of radio frequency (RF) processing circuits for an antenna array. The method may include transmitting first calibration signals having a first subcarrier spacing (SCS) through a plurality of RF transmission paths of the plurality of RF processing circuits. The method may include acquiring the first calibration signals through a plurality of RF reception paths of the plurality of RF processing circuits. The method may include identifying a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The method may include performing calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among the plurality of SCSs. The second SCS may indicate a frequency spacing of each of the OFDM symbols. The time interval of each of the above OFDM symbols may be inversely proportional to the second SCS.

[0006] A non-transitory computer-readable storage medium comprising one or more programs is provided. The one or more programs may include instructions that, when executed by at least one processor of a communication device, cause the communication device to transmit first calibration signals having a first subcarrier spacing (SCS) via a plurality of RF transmit paths of the plurality of RF processing circuits. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to acquire the first calibration signals via a plurality of RF receive paths of the plurality of RF processing circuits. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to identify a bandwidth in a frequency domain having an amplitude variation of the first calibration signals that is less than a first threshold value and a phase variation of the first calibration signals that is less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to perform calibration by transmitting second calibration signals in orthogonal frequency division multiplexing (OFDM) symbols according to a second SCS corresponding to a bandwidth of the frequency domain among a plurality of SCSs. The second SCS may represent a frequency interval of each of the OFDM symbols. A time interval of each of the OFDM symbols may be inversely proportional to the second SCS.

[0007] In connection with the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0008] Figure 1 illustrates an example of a wireless communication system.

[0009] Figure 2 illustrates the interface between an upper network node and a lower network node.

[0010] Figure 3a is a simplified block diagram of an upper network node.

[0011] Figure 3b is a simplified block diagram of a sub-network node.

[0012] Figure 4 illustrates an example of a resource structure in the time domain and frequency domain.

[0013] Figure 5 is a simplified block diagram of a communication device.

[0014] Figure 6 is a flowchart showing the operation of a communication device for determining the subcarrier spacing of a calibration signal.

[0015] Figure 7 illustrates resource allocation in the time domain for data signals and calibration signals.

[0016] Figure 8 is a flowchart showing the operation of a communication device performing calibration.

[0017] Figures 9a and 9b illustrate examples of calibration performed by a communication device.

[0018] Figure 10 is a flowchart showing the operation of a sub-network node performing calibration.

[0019] Figure 11 shows an example of calibration performance.

[0020] The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

[0021] The various embodiments of the present disclosure described below illustrate a hardware-based approach as an example. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0022] In the following description, terms referring to signals (e.g., packet, message, signal, information, signaling), terms referring to resources (e.g., section, symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion), terms for operational states (e.g., step, operation, procedure), terms referring to data (e.g., packet, message, user stream, information, bit, symbol, codeword), terms referring to channels, terms referring to network entities (distributed unit (DU), radio unit (RU), central unit (CU), CU-CP (control plane), CU-UP (user plane), O-DU (O-RAN (open radio access network) DU), O-RU (O-RAN RU), O-CU (O-RAN Terms such as CU), O-CU-UP (O-RAN CU-CP), O-CU-CP (O-RAN CU-CP)), and components of the device are provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. In addition, terms such as '...part', '...machine', '...object', and '...body' used below may mean at least one shape structure or a unit that processes a function.

[0023] In addition, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled, but this is merely a description for expressing an example and does not exclude descriptions such as "more than" or "less than." A condition described as "more than" may be replaced with "more than," a condition described as "less than" may be replaced with "less than," and a condition described as "more than and less than" may be replaced with "more than and less than." In addition, hereinafter, "A" to "B" mean at least one of elements from A (including A) to B (including B). hereinafter, "C" and / or "D" mean at least one of "C" or "D," that is, including {"C", "D", "C" and "D"}.

[0024] Although this disclosure describes embodiments using terminology used in certain communication standards (e.g., 3rd Generation Partnership Project (3GPP)), this is merely an example for illustrative purposes. Embodiments of this disclosure can also be applied to other communication and broadcasting systems.

[0025] Figure 1 illustrates an example of a wireless communication system.

[0026] Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as some of the nodes utilizing a wireless channel in a wireless communication system. Although FIG. 1 illustrates only one base station, the wireless communication system may further include other base stations identical or similar to the base station (110).

[0027] The base station (110) is a network infrastructure that provides wireless access to the terminal (120). The base station (110) has coverage defined based on the distance at which a signal can be transmitted. In addition to the base station, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5th generation node', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)', or other terms having equivalent technical meanings.

[0028] The terminal (120) is a device used by a user and communicates with the base station (110) via a wireless channel. The link from the base station (110) to the terminal (120) is referred to as a downlink (DL), and the link from the terminal (120) to the base station (110) is referred to as an uplink (UL). In addition, although not shown in FIG. 1, the terminal (120) and another terminal may communicate with each other via a wireless channel. In this case, the link between the terminal (120) and another terminal (device-to-device link, D2D) is referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal (120) may be operated without the involvement of a user. For example, the terminal (120) may be a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, for example, the terminal (120) may be an NB (narrowband)-IoT (internet of things) device.

[0029] The terminal (120) may be referred to as a terminal, or other terms such as 'user equipment (UE),' 'customer premises equipment (CPE),' 'mobile station,' 'subscriber station,' 'remote terminal,' 'wireless terminal,' 'electronic device,' or 'user device,' or other terms having equivalent technical meanings.

[0030] The base station (110) and the terminal (120) can perform beamforming. The base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). In addition, the base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively high frequency band (e.g., FR 2 (or, FR 2-1, FR 2-2, FR 2-3), FR 3 of NR), millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz)). To improve channel gain, the base station (110) and the terminal (120) can perform beamforming. Here, the beamforming can include transmission beamforming and reception beamforming. The base station (110) and the terminal (120) can impart directionality to the transmitted or received signal. To this end, the base station (110) and the terminal (120) can select serving beams through a beam search or beam management procedure. After the serving beams are selected, subsequent communication can be performed through resources that have a QCL relationship with the resource that transmitted the serving beams.

[0031] If large-scale characteristics of a channel carrying a symbol on a first antenna port can be inferred from a channel carrying a symbol on a second antenna port, the first antenna port and the second antenna port can be evaluated to have a QCL relationship. For example, the large-scale characteristics may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and a spatial receiver parameter.

[0032] Although both the base station (110) and the terminal (120) are described as performing beamforming in FIG. 1, the embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Furthermore, the base station may or may not perform beamforming. That is, either only one of the base station and the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0033] In the present disclosure, a beam refers to a spatial flow of a signal in a wireless channel, and is formed by one or more antennas (or antenna elements), and this forming process may be referred to as beamforming. Beamforming may include at least one of analog beamforming and digital beamforming (e.g., precoding). Reference signals transmitted based on beamforming may 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 for each reference signal, an IE such as a CSI-RS resource or an SRS-resource may be used, and this configuration may include information associated with the beam. Information associated with a beam may mean whether the configuration (e.g., a CSI-RS resource) uses the same spatial domain filter as another configuration (e.g., another CSI-RS resource within the same CSI-RS resource set) or a different spatial domain filter, or whether it is quasi-co-located (QCL) with a reference signal, and if so, what type it is (e.g., QCL type A, B, C, D).

[0034] In the past, in communication systems with relatively large cell radius of base stations, each base station was installed to include the functions of a digital processing unit (or distributed unit (DU)) and a radio frequency (RF) processing unit (or radio unit (RU)). However, as higher frequency bands are used in 4G (4th generation) and / or subsequent communication systems (e.g., 5G) and the cell coverage of base stations becomes smaller, the number of base stations to cover a specific area has increased. The installation costs for operators to install base stations have also increased. In order to minimize the installation costs of base stations, a structure has been proposed in which the DU and RU of a base station are separated, one or more RUs are connected to one DU via a wired network, and one or more RUs are geographically distributed to cover a specific area. Hereinafter, the deployment structure and expansion examples of base stations according to various embodiments of the present disclosure are described through FIG. 2.

[0035] Figure 2 illustrates the interface between an upper network node and a lower network node.

[0036] The interface between the upper network node and the lower network node may include a fronthaul interface. Unlike the backhaul between the base station and the core network, the fronthaul refers to the entity between the wireless LAN and the base station. While FIG. 2 illustrates an example of a fronthaul structure between an upper network node (210) and one lower network node (220), this is merely for convenience of explanation and the present disclosure is not limited thereto. In other words, embodiments of the present disclosure may also be applied to a fronthaul structure between one upper network node and multiple lower network nodes. For example, embodiments of the present disclosure may be applied to a fronthaul structure between one upper network node and two lower network nodes. Furthermore, embodiments of the present disclosure may also be applied to a fronthaul structure between one upper network node and three lower network nodes.

[0037] For example, an upper network node may include a digital unit / distributed unit (DU). The upper network node may be referred to as a DU. A lower network node may include a radio unit (RU) or a massive MIMO unit (MMU). The lower network node may be referred to as a RU or an MMU.

[0038] Referring to FIG. 2, a base station (110) may include an upper network node (210) and a lower network node (220). A fronthaul (215) between the upper network node (210) and the lower network node (220) may be operated via an Fx interface. For operation of the fronthaul (215), an interface such as an enhanced common public radio interface (eCPRI) or radio over ethernet (ROE) may be used, for example.

[0039] As communication technology develops, mobile data traffic increases, and accordingly, the bandwidth demand required in the fronthaul between the digital unit and the wireless unit has increased significantly. In a deployment such as a centralized / cloud radio access network (C-RAN), an upper network node (210) performs functions for packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical (PHY), and a lower network node (220) may be implemented to perform functions for the PHY layer in addition to the RF (radio frequency) function.

[0040] The upper network node (210) may be responsible for upper layer functions of a wireless network. For example, the upper network node (210) may perform functions of the MAC layer and a part of the PHY layer. Here, a part of the PHY layer refers to functions performed at a higher level among the functions of the PHY layer, and may include, for example, channel encoding (or channel decoding), scrambling (or descrambling), modulation (or demodulation), and layer mapping (or layer demapping). According to an embodiment, when the upper network node (210) complies with the O-RAN standard, it may be referred to as an O-DU (O-RAN DU) (or DU). The upper network node (210) may be replaced with a first network entity or DU for a base station (e.g., gNB) in embodiments of the present disclosure, as needed.

[0041] The lower network node (220) may be responsible for lower layer functions of the wireless network. For example, the lower network node (220) may perform a part of the PHY layer, an RF function. Here, a part of the PHY layer refers to functions of the PHY layer that are performed at a relatively lower level than the upper network node (210), and may include, for example, iFFT transformation (or FFT transformation), CP (cyclic prefix) insertion (CP removal), and digital beamforming. The lower network node (220) may be referred to as an 'access unit (AU)', 'access point (AP)', 'transmission / reception point (TRP)', 'remote radio head (RRH)', 'radio unit (RU)', or other terms having an equivalent technical meaning thereto. In one embodiment, if a lower network node (220) complies with the O-RAN standard, it may be referred to as an O-RU (O-RAN RU) (or RU). The lower network node (220) may be replaced with a second network entity or RU for a base station (e.g., gNB) in embodiments of the present disclosure, as needed.

[0042] Although the above example describes that the upper network node (210) includes a DU and the lower network node (220) includes an RU, the embodiments of the present disclosure are not limited thereto. A base station according to the embodiments may be implemented in a distributed deployment according to a centralized unit (CU) configured to perform functions of upper layers of an access network (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)) and a distributed unit (DU) configured to perform functions of lower layers. At this time, the distributed unit (DU) may include a digital unit (DU) and a radio unit (RU). Between a core (e.g., 5GC (5G core) or NGC (next generation core)) network and a radio network (RAN), the base station may be implemented in a structure in which CU, DU, and RU are arranged in that order. The interface between the CU and the distributed unit (DU) may be referred to as an F1 interface.

[0043] For example, a centralized unit (CU) may be connected to one or more DUs and may be responsible for functions at a higher layer than the DU. For example, the CU may be responsible for functions at the RRC (radio resource control) and PDCP (packet data convergence protocol) layers, while the DU and RU may be responsible for functions at lower layers. The DU may perform some functions (high PHY) of the RLC (radio link control), MAC (media access control), and PHY (physical) layers, and the RU may be responsible for the remaining functions (low PHY) of the PHY layer. In addition, for example, a digital unit (DU) may be included in a distributed unit (DU) depending on the implementation of a distributed deployment of a base station. Hereinafter, unless otherwise defined, the operations of DU and RU are described, but various embodiments of the present disclosure can be applied to both a base station deployment including a CU and a deployment in which the DU is directly connected to the core network (i.e., a base station in which the CU and DU are integrated into a single entity (e.g., an NG-RAN node)).

[0044] Figure 3a is a simplified block diagram of an upper network node.

[0045] The configuration illustrated in Fig. 3a can be understood as a configuration of a higher-level network node (e.g., a DU (distributed unit)) of Fig. 2, as part of a base station. Terms such as "...unit" and "...unit" used hereinafter refer to a unit that processes at least one function or operation, and this can be implemented using hardware, software, or a combination of hardware and software.

[0046] Referring to FIG. 3a, the upper network node (210) may include a transceiver (310), a memory (320), and a processor (330).

[0047] The transceiver (310) can perform functions for transmitting and receiving signals in a wired communication environment. The transceiver (310) can include a wired interface for controlling direct connections between devices and other devices via a transmission medium (e.g., copper wire, optical fiber, etc.). For example, the transceiver (310) can transmit electrical signals to other devices via copper wire or perform conversion between electrical signals and optical signals. The upper network node (210) can communicate with the lower network node (220) via the transceiver (310). The upper network node (210) can be connected to a core network or a centralized unit (CU) of a distributed arrangement via the transceiver (310).

[0048] The transceiver (310) may perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver (310) may perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the transceiver (310) may generate complex symbols by encoding and modulating the transmitted bit stream. For example, when receiving data, the transceiver (310) may decode the baseband signal to restore the received bit stream. For example, the transceiver (310) may include multiple transmission and reception paths. For example, the transceiver (310) may be connected to the core network or to other nodes (e.g., an integrated access backhaul (IAB)).

[0049] The transceiver (310) can transmit and receive signals. For example, the transceiver (310) can transmit a management plane (M-plane) message. For example, the transceiver (310) can receive a synchronization plane (S-plane) message. For example, the transceiver (310) can transmit a control plane (C-plane) message. For example, the transceiver (310) can transmit a user plane (U-plane) message. For example, the transceiver (310) can receive a user plane message. Although FIG. 3A only illustrates the transceiver (310), according to another implementation example, the upper network node (210) may include two or more transceivers.

[0050] The transceiver (310) can transmit and receive signals as described above. Accordingly, all or part of the transceiver (310) may be referred to as a "communication unit," a "transmitter," a "receiver," or a "transmitter-receiver unit." Furthermore, in the following description, transmission and reception performed via a wireless channel may be used to mean processing performed by the transceiver (310) as described above.

[0051] Although not illustrated in FIG. 3A, the transceiver (310) may further include a backhaul transceiver for connection to the core network or other base stations. For example, the backhaul transceiver may provide an interface for communicating with other nodes within the network. For example, the backhaul transceiver may convert a bit stream transmitted from the base station to other nodes, such as other access nodes, other base stations, upper nodes, the core network, etc., into a physical signal, and may convert a physical signal received from other nodes into a bit stream.

[0052] The memory (320) can store data such as basic programs, application programs, and setting information for the operation of the upper network node (210). For example, the memory (320) may be referred to as a storage unit. For example, the memory (320) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. For example, the memory (320) may provide stored data upon request from the processor (330).

[0053] The processor (330) can control the overall operations of the upper network node (210). For example, the processor (330) may be referred to as a control unit. For example, the processor (330) can transmit and receive signals through the transceiver (310) (or through the backhaul communication unit). For example, the processor (330) can write and read data to and from the memory (320). For example, the processor (330) can perform the functions of a protocol stack required by a communication standard. Although FIG. 3A only illustrates the processor (330), the upper network node (210) may include two or more processors according to other implementation examples.

[0054] The configuration of the upper network node (210) illustrated in FIG. 3A is merely an example, and examples of upper network nodes performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 3A. In some embodiments, some configurations may be added, deleted, or changed.

[0055] Figure 3b is a simplified block diagram of a sub-network node.

[0056] The configuration illustrated in Fig. 3b can be understood as a configuration of a lower network node (e.g., a radio unit (RU)) of Fig. 2 as part of a base station. Terms such as "...unit" and "...unit" used hereinafter mean a unit that processes at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software.

[0057] Referring to FIG. 3b, a lower network node (220) may include a radio frequency (RF) transceiver (360), a fronthaul transceiver (365), a memory (370), and a processor (380).

[0058] The RF transceiver (360) can perform functions for transmitting and receiving signals via a wireless channel. For example, the RF transceiver (360) can up-convert a baseband signal into an RF band signal and then transmit the up-converted signal via an antenna, and down-convert an RF band signal received via the antenna into a baseband signal. For example, the RF transceiver (360) can include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like.

[0059] The RF transceiver (360) may include multiple transmit / receive paths. For example, the RF transceiver (360) may include an antenna section. For example, the RF transceiver (360) may include at least one antenna array composed of multiple antenna elements. For example, in terms of hardware, the RF transceiver (360) may be composed of digital circuits and analog circuits (e.g., a radio frequency integrated circuit (RFIC)). For example, the digital circuits and analog circuits may be implemented in a single package. For example, the RF transceiver (360) may include multiple RF chains. For example, the RF transceiver (360) may perform beamforming. For example, the RF transceiver (360) may apply beamforming weights to a signal to be transmitted / received in order to impart directionality according to the settings of the processor (380). For example, the RF transceiver (360) may include an RF block (or RF section).

[0060] For example, the RF transceiver (360) can transmit and receive signals on a radio access network. For example, the RF transceiver (360) can transmit a downlink signal. For example, the downlink signal can include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS), 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. For example, the RF transceiver (360) can receive an uplink signal. For example, the uplink signal may include a random access related signal (e.g., a random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), a reference signal (e.g., a sounding reference signal (SRS), DM-RS), or a power headroom report (PHR). Although FIG. 3b only illustrates an RF transceiver (360), in other implementations, the lower network node (220) may include two or more RF transceivers.

[0061] The fronthaul transceiver (365) can transmit and receive signals. For example, the fronthaul transceiver (365) can transmit and receive signals on the fronthaul interface. For example, the fronthaul transceiver (365) can receive management plane (M-plane) messages. For example, the fronthaul transceiver (365) can receive synchronization plane (S-plane) messages. For example, the fronthaul transceiver (365) can receive control plane (C-plane) messages. For example, the fronthaul transceiver (365) can transmit user plane (U-plane) messages. For example, the fronthaul transceiver (365) can receive user plane messages. Although FIG. 3b illustrates only the fronthaul transceiver (365), in other implementation examples, the lower network node (220) may include two or more fronthaul transceivers.

[0062] The RF transceiver (360) and the fronthaul transceiver (365) can transmit and receive signals as described above. Accordingly, all or part of the RF transceiver (360) and the fronthaul transceiver (365) may be referred to as a "communication unit," a "transmitter," a "receiver," or a "transmitter-receiver unit." In the following description, transmission and reception performed through a wireless channel may be used to mean that the processing described above is performed by the RF transceiver (360).

[0063] The memory (370) can store data such as basic programs, application programs, and setting information for the operation of the lower network node (220). For example, the memory (370) may be referred to as a storage unit. For example, the memory (370) may be configured as volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. For example, the memory (370) provides stored data according to a request from the processor (380). For example, the memory (370) may include memory for conditions, commands, or setting values ​​related to the SRS transmission method.

[0064] The processor (380) can control the overall operations of the lower network node (220). For example, the processor (380) may be referred to as a control unit. For example, the processor (380) can transmit and receive signals through the RF transceiver (360) or the fronthaul transceiver (365). For example, the processor (380) can write and read data to and from the memory (370). For example, the processor (380) can perform the functions of the protocol stack required by the communication standard. Although FIG. 3B only illustrates the processor (380), the lower network node (220) may include two or more processors according to other implementation examples. For example, the processor (380) may be a set of instructions or codes stored in the memory (370), or may be a storage space that stores instructions / codes or instructions / codes that are at least temporarily residing in the processor (380), or may be a part of the circuitry that constitutes the processor (380). For example, the processor (380) may include various modules for performing communication. For example, the processor (380) may control the lower network node (220) to perform operations according to the embodiments described below.

[0065] The configuration of the lower network node (220) illustrated in FIG. 3b is merely an example, and examples of lower network nodes performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 3b. In some embodiments, some configurations may be added, deleted, or changed.

[0066] Figure 4 illustrates an example of a resource structure in the time domain and frequency domain.

[0067] Figure 4 illustrates the basic structure of the time-frequency domain, which is a radio resource region in which data or control channels are transmitted in the downlink or uplink.

[0068]

[0069]

[0070] In the NR system, in the case of a frequency division duplex (FDD) system that operates the downlink and uplink by frequency division, the downlink transmission bandwidth and the uplink transmission bandwidth may be different. The channel bandwidth represents the radio frequency (RF) bandwidth corresponding to the system transmission bandwidth. [Table 1] shows part of the correspondence between the system transmission bandwidth, subcarrier spacing (SCS), and channel bandwidth defined in the NR system in a frequency band lower than x GHz (e.g., frequency range (FR) 1 (410 MHz to 7125 MHz)). And [Table 2] shows part of the correspondence between the transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a frequency band higher than y GHz (e.g., FR2 (24250 MHz - 52600 MHz) or FR2-2 (52600 MHz to 71000 MHz)). For example, an NR system with a 100 MHz channel bandwidth and a 30 kHz subcarrier spacing has a transmission bandwidth of 273 RBs. In [Table 1] and [Table 2], N / A may be a bandwidth-subcarrier combination not supported by the NR system.

[0071]

[0072]

[0073] Hereinafter, the present disclosure is described as an operation between a base station (110) and a terminal (120) or an operation between a communication device and a terminal (120). In one example, the communication device may correspond to a base station (110) that includes an upper network node (210) (e.g., a distributed unit (DU)) and a lower network node (220) (e.g., a radio unit (RU)). In one example, the communication device may correspond to an upper network node (210). In one example, the communication device may correspond to a lower network node (220).

[0074] In the following description, the base station (110) may be functionally separated into an upper network node (210) and a lower network node (220) to perform communication with the terminal (120). For example, it may be understood that the upper network node (210) performs communication with the terminal (120) through the lower network node (220) as an embodiment of the present disclosure. For example, the base station (110) transmitting a downlink signal (e.g., a channel state information-reference signal (CSI-RS)) to the terminal (120) may include the upper network node (210) transmitting a downlink signal through the lower network node (220). For example, the base station (110) receiving an uplink signal (e.g., a sounding reference signal (SRS)) from the terminal (120) may include the upper network node (210) receiving an uplink signal through the lower network node (220).

[0075] Figure 5 is a simplified block diagram of a communication device. For example, the communication device may correspond to a base station (110) that includes an upper network node (210) (e.g., a distributed unit (DU)) and a lower network node (220) (e.g., a radio unit (RU)). In another example, the communication device may correspond to a lower network node (220).

[0076] Referring to FIG. 5, the communication device includes a processor (510), a plurality of digital up converters (DUCs) (520-1, 520-2, 520-3, ..., 520-n), a plurality of digital down converters (DDCs) (521-1, 521-2, 521-3, ..., 521-n), a plurality of radio frequency (RF) transmitters (530-1, 530-2, 530-3, ..., 530-n), a plurality of RF receivers (531-1, 531-2, 531-3, ..., 531-n), a plurality of time division duplexing (TDD) switches (540-1, 540-2, 540-3, ..., 540-n), a plurality of couplers (550-1, 550-2, 550-3, ..., 550-n), a plurality of antennas (560-1, 560-2, 560-3, ..., 560-n), a combiner (570), and a divider (580).

[0077] For example, the plurality of DUCs (520-1, 520-2, 520-3, ..., 520-n) may be configured to convert a digital signal generated in a baseband into a radio frequency (RF) band signal in each transmission path. For example, the plurality of RF transmitters (530-1, 530-2, 530-3, ..., 530-n) may be configured to convert a digital signal up-converted by the plurality of DUCs (520-1, 520-2, 520-3, ..., 520-n) in each transmission path into an analog signal (e.g., digital to analog converting (DAC)). For example, a plurality of RF receivers (531-1, 531-2, 531-3, ..., 531-n) may be configured to convert analog signals received in each receiving path into digital signals (e.g., analog to digital converting (ADC)). For example, a plurality of DDCs (521-1, 521-2, 521-3, ..., 521-n) may be configured to convert digital signals in an RF band into baseband signals in each receiving path. FIG. 5 illustrates a plurality of DUCs (520-1, 520-2, 520-3, ..., 520-n), a plurality of DDCs (521-1, 521-2, 521-3, ..., 521-n), a plurality of RF transmitters (530-1, 530-2, 530-3, ..., 530-n), and a plurality of RF receivers (531-1, 531-2, 531-3, ..., 531-n) as separate components, but the present disclosure is not limited thereto. For example, a plurality of DUCs (520-1, 520-2, 520-3, ..., 520-n), a plurality of DDCs (521-1, 521-2, 521-3, ..., 521-n), a plurality of RF transmitters (530-1, 530-2, 530-3, ..., 530-n), and a plurality of RF receivers (531-1, 531-2, 531-3, ..., 531-n) may be co-configured within the RF processing circuit(s).

[0078] For example, the RF processing circuit(s) may include a plurality of transmit paths. For example, the number of the plurality of transmit paths of the RF processing circuit may correspond to the number of antennas (560-1, 560-2, 560-3, ..., 560-n) of the communication device. In one example, a first transmit path of the RF processing circuit may include a DUC (520-1) and an RF transmitter (530-1). In one example, a second transmit path of the RF processing circuit may include a DUC (520-2) and an RF transmitter (530-2). In one example, a third transmit path of the RF processing circuit may include a DUC (520-3) and an RF transmitter (530-3). In one example, an n-th transmit path of the RF processing circuit may include a DUC (520-n) and an RF transmitter (530-n).

[0079] For example, the RF processing circuit may include a plurality of receive paths. For example, the number of the plurality of receive paths of the RF processing circuit may correspond to the number of antennas (560-1, 560-2, 560-3, ..., 560-n) of the communication device. In one example, a first receive path of the RF processing circuit may include an RF receiver (531-1) and a DDC (521-1). In one example, a second receive path of the RF processing circuit may include an RF receiver (531-2) and a DDC (521-2). In one example, a third receive path of the RF processing circuit may include an RF receiver (531-3) and a DDC (521-3). In one example, an n-th receive path of the RF processing circuit may include an RF receiver (531-n) and a DDC (521-n).

[0080] For example, the TDD switches (540-1, 540-2, 540-3, ..., 540-n) may be configured to select one of the transmit paths and the receive paths. For example, the plurality of couplers (550-1, 550-2, 550-3, ..., 550-n) may be configured to transmit calibration signals received through the plurality of transmit paths to the combiner (570). For example, the combiner (570) may be configured to combine calibration signals transmitted through the plurality of transmit paths in a time-division manner. For example, the distributor (580) may be configured to copy the combined calibration signals and distribute them to the plurality of receive paths.

[0081] For example, the processor (510) may include a transmission / reception data buffer (511), a signal switching device (512), modems (513-1, 513-2, 513-3, ..., 513-n), a calibration signal processing unit (514), a calibration signal generator (515), and a calibration signal buffer (516). For example, the transmission / reception data buffer (511) may be configured to temporarily store an uplink signal and / or a downlink signal. For example, the signal switching device (512) may be configured to provide one of data signals and calibration signals as an input of the modems (513-1, 513-2, 513-3, ..., 513-n).

[0082] For example, the modems (513-1, 513-2, 513-3, ..., 513-n) may be configured to perform channel encoding / scrambling, modulation, layer mapping, antenna port mapping, resource element (RE) mapping, digital beamforming (e.g., precoding), and inverse fast fourier transform (iFFT) / cyclic prefix (CP) insertion on signals transmitted through the transmission path. For example, the modems (513-1, 513-2, 513-3, ..., 513-n) may be configured to perform FFT transform / CP removal, digital beamforming (e.g., pre-combining, RE de-mapping, channel estimation, layer de-mapping, demodulation, decoding / descrambling) on ​​the signal received through the receive path. However, this is merely an example, and the present disclosure is not limited thereto. For example, depending on the functional separation between the upper network node (210) and the lower network node (220), the modems (513-1, 513-2, 513-3, ..., 513-n) may be configured to perform only some of channel encoding / scrambling, modulation, layer mapping, antenna port mapping, RE mapping, digital beamforming, iFFT transform / CP insertion on the signal transmitted through the transmit path. For example, depending on the functional separation between the upper network node (210) and the lower network node (220), the modems (513-1, 513-2, 513-3, ..., 513-n) may be configured to perform only some of FFT transform / CP removal, digital beamforming, RE de-mapping, channel estimation, layer de-mapping, demodulation, and decoding / descrambling for signals received through the receiving path.

[0083] For example, the calibration signal processing unit (514) may be configured to determine a numerology (or subcarrier spacing (SCS)) for calibration based on calibration signals received from modems (513-1, 513-2, 513-3, ..., 513-n). For example, the calibration signal generator (515) may be configured to generate calibration signals. For example, the calibration signal buffer (516) may be configured to store calibration signals received from (513-1, 513-2, 513-3, ..., 513-n).

[0084] Referring to FIG. 5, the downlink / uplink signal may change in amplitude and phase depending on the hardware characteristics (e.g., temperature) of the RF processing circuit as it passes through the RF processing circuit. To compensate for the changes in amplitude and phase due to the hardware characteristics of the RF processing circuit in advance, calibration signals may be used. The calibration signals may be transmitted on orthogonal frequency division multiplexing (OFDM) symbols corresponding to the number of antennas. However, as the number of antennas increases, the duration of the time resources allocated for the calibration signals may increase. Below, a method and device for changing the subcarrier spacing (SCS) of the calibration signals to reduce the duration of the time resources allocated for the calibration signals are described.

[0085] FIG. 6 is a flowchart illustrating the operation of a communication device for determining a subcarrier spacing of a calibration signal. For example, the communication device may correspond to a base station (110) including an upper network node (210) (e.g., a distributed unit (DU)) and a lower network node (220) (e.g., a radio unit (RU)). In another example, the communication device may correspond to a lower network node (220). In the following, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed. For example, at least two operations may be performed in parallel. FIG. 6 may be described with reference to the descriptions of FIG. 5.

[0086] Referring to FIG. 6, in operation 601, the communication device may transmit first calibration signals having a first subcarrier spacing (SCS) through a plurality of radio frequency (RF) transmission paths.

[0087] In one embodiment, the communication device may transmit first calibration signals having a first subcarrier spacing through a plurality of RF transmission paths of the RF processing circuit. For example, the number of the plurality of RF transmission paths of the RF processing circuit may correspond to the number of antennas of the communication device. In one example, if the number of antennas of the communication device is 32, the number of the plurality of RF transmission paths may be 32. However, this is merely an example, and the present disclosure is not limited thereto.

[0088] In one embodiment, each of the plurality of RF transmission paths may include a digital up converter (DUC) and an RF transmitter. In one example, the plurality of RF transmission paths may include a first RF transmission path through an n-th RF transmission path. The first RF transmission path may include a first DUC (e.g., DUC 520-1) and a first RF transmitter (e.g., RF transmitter 530-1). The second RF transmission path may include a second DUC (e.g., DUC 520-2) and a second RF transmitter (e.g., RF transmitter 530-2). The third RF transmission path may include a third DUC (e.g., DUC 520-3) and a second RF transmitter (e.g., RF transmitter 530-3). The n-th RF transmission path may include a second DUC (e.g., DUC 520-n) and a second RF transmitter (e.g., RF transmitter 530-n).

[0089] In one embodiment, the first calibration signals may be transmitted in different orthogonal frequency division multiplexing (OFDM) symbols. For example, by transmitting the first calibration signals in different symbols, interference between the first calibration signals may be prevented. In one example, the first calibration signals may include a first signal through an nth signal. The communication device may transmit the first signal in a first OFDM symbol via a first RF transmission path. The communication device may transmit the second signal in a second OFDM symbol different from the first OFDM symbol via a second RF transmission path. The communication device may transmit the third signal in a third OFDM symbol different from the first OFDM symbol and the second OFDM symbol via a third RF transmission path. The communication device may transmit the nth signal in an nth OFDM symbol different from the first OFDM symbol through the nth RF transmission path.

[0090] In one embodiment, the first calibration signals may have a first subcarrier spacing. In one example, when the first subcarrier spacing is 60 kHz, the length of the OFDM symbol through which the first calibration signals are transmitted may be 16.67 microseconds (us), excluding the cyclic prefix (CP).

[0091] In operation 602, the communication device may obtain first calibration signals having a first subcarrier spacing through a plurality of RF reception paths. For example, the first calibration signals obtained through the plurality of RF reception paths may be calibration signals whose amplitude and phase are changed by an RF transmission circuit and an RF reception circuit.

[0092] In one embodiment, the communication device can obtain first calibration signals having a first subcarrier spacing through a plurality of RF receiving paths of the RF processing circuit. For example, the number of the plurality of RF receiving paths of the RF processing circuit can correspond to the number of antennas of the communication device. In one example, when the number of antennas of the communication device is 32, the number of the plurality of RF receiving paths can be 32. However, this is merely an example, and the present disclosure is not limited thereto.

[0093] In one embodiment, each of the plurality of RF receive paths may include an RF receiver and a digital down converter (DDC). In one example, the plurality of RF receive paths may include a first RF receive path through an n-th RF receive path. The first RF receive path may include a first RF receiver (e.g., RF receiver 531-1) and a first DDC (e.g., DDC 521-1). The second RF receive path may include a second RF receiver (e.g., RF receiver 531-2) and a second DDC (e.g., DDC 521-2). The third RF receive path may include a third RF receiver (e.g., RF receiver 531-3) and a third DDC (e.g., DDC 521-3). The n-th RF receive path may include an n-th RF receiver (e.g., RF receiver 531-n) and an n-th DDC (e.g., DDC 521-n). For example, the first calibration signals obtained through multiple RF receiving paths may mean signals whose amplitude and phase have been changed through the RF transmitting paths and RF receiving paths of the RF processing circuit.

[0094] In operation 603, the communication device can identify a second subcarrier spacing for the second calibration signals based on the first calibration signals.

[0095] In one embodiment, a communication device may acquire calibration information based on first calibration signals acquired through multiple RF reception paths. For example, the calibration information may include information regarding amplitude variation of the first calibration signals and information regarding phase variation of the first calibration signals.

[0096] For example, the communication device can obtain information about the amplitude variation amount and the phase variation amount of the first calibration signals based on the reference calibration signal and the first calibration signals obtained through the plurality of reception RF paths. For example, the reference calibration signal may mean a calibration signal having a predetermined amplitude and a predetermined phase. In one example, the first calibration signals transmitted through the plurality of RF transmission paths may correspond to the reference calibration signal. For example, the communication device can obtain information about the amplitude variation amount and the phase variation amount of the first calibration signals by comparing the first calibration signals obtained through the plurality of RF reception paths and the reference calibration signal. For example, the information about the amplitude variation amount may include information about the amplitude variation amount of the first calibration signals in the time domain and / or information about the amplitude variation amount of the first calibration signals in the frequency domain. For example, the information about the phase shift may include information about the phase shift of the first calibration signals in the time domain and / or information about the phase shift of the first calibration signals in the frequency domain.

[0097] In one embodiment, the communication device can identify a coherent bandwidth based on information about an amplitude change of the first calibration signals and information about a phase change of the first calibration signals.

[0098] In one embodiment, the coherent bandwidth may represent a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value. However, this is merely an example, and the present disclosure is not limited thereto. For example, the coherent bandwidth may represent a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value. In another example, the coherent bandwidth may represent a bandwidth in a frequency domain having a phase variation of the first calibration signals less than a second threshold value. For example, the first threshold value and the second threshold value may be predetermined.

[0099] In one embodiment, the communication device may identify a second subcarrier spacing for the second calibration signals based on the coherent bandwidth. For example, the second calibration signals may refer to calibration signals transmitted in a subsequent period of the first calibration signals. In another example, the second calibration signals may refer to calibration signals subsequent to the first calibration signals.

[0100] For example, the communication device may identify a second subcarrier spacing corresponding to a coherent bandwidth among a plurality of subcarrier spacings. For example, the plurality of subcarrier spacings may include a first level subcarrier spacing (e.g., 15 kHz), a second level subcarrier spacing (e.g., 30 kHz), a third level subcarrier spacing (e.g., 60 kHz), a fourth level subcarrier spacing (e.g., 120 kHz), a fifth level subcarrier spacing (e.g., 240 kHz), a sixth level subcarrier spacing (e.g., 480 kHz), and a seventh level subcarrier spacing (e.g., 960 kHz). However, this is merely an example, and the present disclosure is not limited thereto. For example, the plurality of subcarrier spacings may include only some of the subcarrier spacing of the first level (e.g., 15 kHz), the subcarrier spacing of the second level (e.g., 30 kHz), the subcarrier spacing of the third level (e.g., 60 kHz), the subcarrier spacing of the fourth level (e.g., 120 kHz), the subcarrier spacing of the fifth level (e.g., 240 kHz), the subcarrier spacing of the sixth level (e.g., 480 kHz), and the subcarrier spacing of the seventh level (e.g., 960 kHz). In another example, the plurality of subcarrier spacings may further include the subcarrier spacing of the eighth level (e.g., 1920 kHz).

[0101] In one example, the communication device can identify a second subcarrier spacing for the second calibration signals based on ranges specified in association with the coherent bandwidth. The communication device can identify the second subcarrier spacing for the second calibration signals as a first level subcarrier spacing (e.g., 15 kHz) when the coherent bandwidth is within a first range (e.g., less than 30 kHz). The communication device can identify the second subcarrier spacing for the second calibration signals as a second level subcarrier spacing (e.g., 30 kHz) when the coherent bandwidth is within a second range (e.g., greater than or equal to 30 kHz and less than or equal to 60 kHz). The communication device can identify the second subcarrier spacing for the second calibration signals as a third level subcarrier spacing (e.g., 60 kHz) when the coherent bandwidth is within a third range (e.g., greater than or equal to 60 kHz and less than 120 kHz). The communication device may identify the second subcarrier spacing for the second calibration signals as a fourth level subcarrier spacing (e.g., 120 kHz) when the coherent bandwidth is within a fourth range (e.g., 120 kHz or more and less than 240 kHz). The communication device may identify the second subcarrier spacing for the second calibration signals as a fifth level subcarrier spacing (e.g., 240 kHz) when the coherent bandwidth is within a first range (e.g., 240 kHz or more and less than 480 kHz). The communication device may identify the second subcarrier spacing for the second calibration signals as a sixth level subcarrier spacing (e.g., 480 kHz) when the coherent bandwidth is within a first range (e.g., 480 kHz or more and less than 960 kHz). The communication device may identify the second subcarrier spacing for the second calibration signals as a seventh level subcarrier spacing (e.g., 960 kHz) when the coherent bandwidth is within the seventh range (e.g., 960 kHz or greater).However, this is merely an example, and the present disclosure is not limited to the examples described above. For example, the coherent bandwidth and the second subcarrier spacing for the second calibration signals may have a monotonically increasing relationship.

[0102] In one example, the communication device can identify a second subcarrier spacing for the second calibration signals based on the coherent bandwidth. The second subcarrier spacing may be greater than the first subcarrier spacing of the data signals. Since the subcarrier spacing and the OFDM symbol length are inversely proportional, the OFDM symbol length for transmitting the second calibration signals may be less than the OFDM symbol length for transmitting the data signals. As the OFDM symbol length becomes shorter, the time-domain duration for allocating the second calibration signals may also become shorter. As the time-domain duration for allocating the second calibration signals becomes shorter, the communication device can allocate more data signals to the time resource. Since more data signals are allocated to the time resource, data transmission efficiency may be improved.

[0103] In another example, the communication device can identify a second subcarrier spacing for the second calibration signals based on the coherent bandwidth. The second subcarrier spacing may be smaller than the first subcarrier spacing of the data signals. Since the subcarrier spacing and the OFDM symbol length are inversely proportional, the OFDM symbol length over which the second calibration signals are transmitted may be larger than the OFDM symbol length over which the data signals are transmitted. As the OFDM symbol length increases, the time domain interval to which the second calibration signals are allocated may increase. The communication device can minimize the influence of the multiple RF transmission paths and the multiple RF reception paths by performing calibration using the second calibration signals in the interval.

[0104] In one embodiment, the communication device can identify coherent time based on information about an amplitude change of the first calibration signals and information about a phase change of the first calibration signals.

[0105] In one embodiment, coherent time may represent a time domain interval having an amplitude variation of the first calibration signals less than a third threshold value and a phase variation of the first calibration signals less than a fourth threshold value. However, this is merely an example, and the present disclosure is not limited thereto. For example, coherent time may represent a time domain interval having an amplitude variation of the first calibration signals less than a third threshold value. In another example, coherent time may represent a time domain interval having a phase variation of the first calibration signals less than a fourth threshold value.

[0106] In one embodiment, the communication device may identify the transmission periodicity for the second calibration signals based on coherent time. For example, the second calibration signals may refer to calibration signals transmitted in a subsequent period of the first calibration signals. In another example, the second calibration signals may refer to calibration signals subsequent to the first calibration signals.

[0107] In one example, the communication device can identify a second transmission period for the second calibration signals based on coherent time. The second transmission period can be longer than the first transmission period of the first calibration signals. Since the second transmission period of the second calibration signals is longer than the first transmission period of the first calibration signals, the second calibration signals can be allocated less frequently than the first calibration signals. Since the second calibration signals are allocated less frequently, the communication device can allocate more data signals to time resources. Since the data signals are allocated more frequently to time resources, data transmission efficiency can be improved.

[0108] In another example, the communication device can identify a second transmission period for the second calibration signals based on coherent time. The second transmission period can be shorter than the first transmission period of the first calibration signals. Since the second transmission period of the second calibration signals is shorter than the first period of the first calibration signals, the second calibration signals can be allocated more frequently than the first calibration signals. The communication device can minimize the influence of the multiple RF transmission paths and the multiple RF reception paths by transmitting the second calibration signals more frequently than the first calibration signals.

[0109] In operation 604, the communication device can perform calibration by transmitting second calibration signals having a second subcarrier spacing. The procedure for performing calibration by transmitting the second calibration signals is described in FIG. 8 below.

[0110] Figure 7 illustrates resource allocation in the time domain for data signals and calibration signals. Figure 7 illustrates an example of improving data transmission efficiency by identifying subcarrier spacing for second calibration signals based on first calibration signals. Figure 7 is described with reference to the description of Figure 6.

[0111] Referring to FIG. 7, at a first time (710), the communication device may transmit first calibration signals having a first subcarrier spacing (e.g., 60 kHz) and data signals having a first subcarrier spacing (e.g., 60 kHz) through a plurality of RF transmission paths of the RF processing circuit. An OFDM symbol through which the first calibration signals and data signals are transmitted may have a first length (e.g., 16.67 us) excluding a cyclic prefix (CP). In the example illustrated in FIG. 7, the communication device may include 32 antennas. The first calibration signals may be transmitted in 32 symbols (715) corresponding to the number of antennas of the communication device. Since a slot includes 14 symbols, slot (712), slot (712), and slot (713) may be allocated for transmission of the first calibration signals. Symbols (730) represent symbols of slots allocated for first calibration signals. Symbols (740) represent symbols through which first calibration signals are transmitted. Data signals may be transmitted in slots (711).

[0112] In one embodiment, a communication device can transmit first calibration signals through a plurality of RF transmission paths of an RF processing circuit. The communication device can obtain first calibration signals through a plurality of RF reception paths of the RF processing circuit. The first calibration signals obtained through the plurality of RF reception paths may refer to signals whose amplitudes and phases are changed through the RF transmission paths and the RF reception paths of the RF processing circuit. The communication device can obtain information about an amplitude variation of the first calibration signals and information about a phase variation of the first calibration signals by comparing the first calibration signals obtained through the plurality of RF reception paths of the RF processing circuit with a reference calibration signal. The communication device can identify a coherent bandwidth based on the information about the amplitude variation and the information about the phase variation. The communication device can identify a second subcarrier spacing (e.g., 240 kHz) for the second calibration signals based on the identified coherent bandwidth.

[0113] Referring to FIG. 7, at a second time (720), the communication device may transmit second calibration signals having a second subcarrier spacing (e.g., 240 kHz) through a plurality of RF transmission paths of the RF processing circuit. At a second time (720), the communication device may transmit data signals having a first subcarrier spacing (e.g., 60 kHz) through a plurality of RF transmission paths of the RF processing circuit. The OFDM symbol through which the second calibration signals are transmitted may have a second length (e.g., 4.17 us) excluding the CP. The OFDM symbol through which the data signals are transmitted may have a first length (e.g., 16.67 us) excluding the CP. In the example illustrated in FIG. 7, the communication device may include 32 antennas. The second calibration signals may be transmitted in 32 symbols (725) corresponding to the number of antennas of the communication device. In one example, four slots (723) may be allocated to transmit second calibration signals. Symbols (750) represent symbols of slots allocated for second calibration signals. Symbols (760) represent symbols in which second calibration signals are transmitted. Data signals may be transmitted in slots (721), (722), and (724). Compared to the first time (710), in the second time (720), data signals may be further transmitted in slots (722) and (724). Therefore, data transmission efficiency may be improved.

[0114] FIG. 8 is a flowchart illustrating the operation of a communication device performing calibration. For example, the communication device may correspond to a base station (110) including an upper network node (210) (e.g., a distributed unit (DU)) and a lower network node (220) (e.g., a radio unit (RU)). In another example, the communication device may correspond to a lower network node (220). In the following description, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed. For example, at least two operations may be performed in parallel. FIG. 8 describes a procedure for performing calibration by a communication device following the description of FIG. 6. However, the present disclosure is not limited thereto. For example, the operations of the communication device of FIG. 8 may be performed subsequent to operation 602 of FIG. 6.

[0115] Referring to FIG. 8, in operation 801, a communication device may obtain first calibration information for first sub-channels based on calibration signals (e.g., the second calibration signals of FIG. 6). The first calibration information may include information on amplitude variation and phase variation of the first sub-channels corresponding to the subcarrier spacing (SCS) of the calibration signals. For example, the number of first sub-channels may be identified according to the following [Mathematical Formula 1].

[0116]

[0117]

[0118] In one example, when the channel bandwidth is 98.28 MHz and the subcarrier spacing of the calibration signals is 60 kHz, the number of first subchannels of the channel may be 1638. The first calibration information may include information about amplitude variations and information about phase variations of the 1638 first subchannels. In another example, when the channel bandwidth is 98.28 MHz and the subcarrier spacing of the calibration signals is 120 kHz, the number of first subchannels of the channel may be 819. The first calibration information may include information about amplitude variations and information about phase variations of the 819 first subchannels. As in the example described above, as the subcarrier spacing of the calibration signals increases, the number of first subchannels may decrease. Therefore, as the subcarrier spacing of the calibration signals increases, the computational complexity for obtaining the first calibration information of the communication device can be reduced.

[0119] In operation 802, the communication device may identify the bandwidth of the second subchannel based on a resolution factor and the subcarrier spacing of the data signals. For example, the resolution factor may be used to identify the bandwidth of the second subchannel on which calibration for the data signals is performed. For example, the bandwidth of the second subchannel may be identified based on the subcarrier spacing of the data signals and the resolution factor. In one example, when the subcarrier spacing of the data signals is 60 kHz and the resolution factor is 12, the bandwidth of the second subchannel may be identified as 720 kHz. However, the present disclosure is not limited thereto. For example, the number of second subchannels may be identified according to the following [Mathematical Formula 2].

[0120]

[0121]

[0122] In operation 803, the communication device can obtain second calibration information for second sub-channels based on first calibration information for first sub-channels.

[0123] In one embodiment, the communication device may obtain second calibration information for the second subchannel based on first calibration information of first subchannels corresponding to the bandwidth of the second subchannel. In one example, when the bandwidth of the second subchannel is 720 kHz, the second calibration information for the second subchannel (e.g., the second calibration information (903) of FIG. 9A) may be obtained based on first calibration information of 12 first subchannels having a subcarrier spacing of 60 kHz (e.g., the first calibration information (902) of FIG. 9A). In another example, when the bandwidth of the second sub-channel is 720 kHz, the second calibration information for the second sub-channel (e.g., the second calibration information (913) of FIG. 9b) can be obtained based on the first calibration information (e.g., the first calibration information (912) of FIG. 9b) of three first sub-channels having a subcarrier spacing of 240 kHz.

[0124] In operation 804, the communication device may perform calibration on data signals in the second sub-channels based on the second calibration information. For example, the communication device may calibrate the amplitude and phase of data signals in the second sub-channels for each RF transmission (or reception) path based on the second calibration information. An example of performing calibration on data signals in the second sub-channels is described below in FIGS. 9A and 9B .

[0125] Figures 9a and 9b illustrate examples of calibration performed by a communication device.

[0126] In Fig. 9a, a procedure for performing calibration when the subcarrier spacing of the first calibration signals (901) and data signals (904) is 60 kHz is described. Referring to Fig. 9a, a communication device can transmit first calibration signals (901) having a first subcarrier spacing (60 kHz) through a plurality of RF transmission paths of an RF processing circuit. The communication device can obtain first calibration signals (901) having a first subcarrier spacing (60 kHz) through a plurality of RF reception paths of the RF processing circuit. The first calibration signals (901) obtained through the plurality of RF reception paths can have their amplitude and phase changed by the RF transmission path and the RF reception path. The communication device can obtain first calibration information (902) for first sub-channels based on the first calibration signals (901) obtained through the plurality of RF reception paths. For example, the first calibration information (902) may include information about an amplitude variation amount and information about a phase variation amount of the first calibration signals (901) in the first sub-channels, each corresponding to a sub-carrier spacing of the first calibration signals (901). The communication device may identify a bandwidth (720 kHz) of the second sub-channel based on a resolution factor (e.g., 12) and a sub-carrier spacing (60 kHz) of the data signals (904). The communication device may obtain second calibration information (903) for the second sub-channels based on the bandwidth (720 kHz) of the second sub-channel and the first calibration information (902) for the first sub-channels. The communication device can perform calibration for data signals (904) in the second sub-channels (905, 906, 907, 908) for each RF transmission / reception path based on the second calibration information (903).

[0127] In one embodiment, the communication device can identify a coherent bandwidth based on the first calibration information (902) for the first subchannels. For example, the coherent bandwidth can represent a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value. The communication device can identify a second subcarrier spacing (240 kHz) for the second calibration signals (911) based on the coherent bandwidth.

[0128] In Fig. 9b, a procedure for performing calibration when the subcarrier spacing of the second calibration signals (911) is 240 kHz and the subcarrier spacing of the data signals (914) is 60 kHz is described. Referring to Fig. 9b, the communication device can transmit the second calibration signals (911) having the second subcarrier spacing (240 kHz) through a plurality of RF transmission paths of the RF processing circuit. The communication device can obtain the second calibration signals (911) having the second subcarrier spacing (240 kHz) through a plurality of RF reception paths of the RF processing circuit. The second calibration signals (911) obtained through the plurality of RF reception paths can have their amplitude and phase changed by the RF transmission path and the RF reception path. The communication device can obtain first calibration information (921) for the first sub-channels based on the second calibration signals (911) obtained through the plurality of RF receiving paths. For example, the first calibration information (921) can include information on the amplitude variation amount and information on the phase variation amount of the second calibration signals (911) in the first sub-channels, each corresponding to the subcarrier spacing (240 kHz) of the second calibration signals (911). The communication device can identify the bandwidth (720 kHz) of the second sub-channel based on the subcarrier spacing (60 kHz) and the resolution factor (e.g., 12) of the data signals (914). The communication device can obtain second calibration information (913) for the second sub-channels based on the bandwidth (720 kHz) of the second sub-channel and the first calibration information (912) for the first sub-channels. The communication device can perform calibration for data signals (914) in the second sub-channels (915, 916, 917, 918) for each RF transmission / reception path based on the second calibration information (913).

[0129] Figure 10 is a flowchart illustrating the operation of a lower network node performing calibration. For example, the lower network node (220) of Figure 10 may correspond to the communication device described above. In the following description, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed. For example, at least two operations may be performed in parallel.

[0130] Referring to FIG. 10, in operation 1001, a lower network node (220) (e.g., a radio unit (RU)) can identify a subcarrier spacing (SCS) and transmission period for second calibration signals using first calibration signals.

[0131] In one embodiment, a communication device can transmit first calibration signals having a first subcarrier spacing through a plurality of radio frequency (RF) transmission paths. The communication device can obtain the first calibration signals having the first subcarrier spacing through a plurality of RF reception paths. For example, the first calibration signals obtained through the plurality of RF reception paths may have amplitudes and phases changed by the RF transmission path and the RF reception path. The communication device can obtain first calibration information based on the first calibration signals obtained through the plurality of RF reception paths. For example, the first calibration information may include information about an amplitude change amount of the first calibration signals and information about a phase change amount.

[0132] In one embodiment, the communication device can identify a coherent bandwidth based on the first calibration information. For example, the coherent bandwidth can represent a bandwidth in a frequency domain having an amplitude variation of the first calibration signals below a first threshold value and a phase variation of the first calibration signals below a second threshold value. The communication device can identify a second subcarrier spacing for the second calibration signals based on the coherent bandwidth.

[0133] In one embodiment, the communication device can identify a coherent time based on the first calibration information. For example, the coherent time can represent a time domain interval in which the amplitude variation of the first calibration signals is less than a third threshold value and the phase variation of the first calibration signals is less than a second threshold value. The communication device can identify a transmission period for the second calibration signals based on the coherent time.

[0134] In operation 1002, the lower network node (220) may transmit a first message to the upper network node (210). For example, the first message may include information about the second subcarrier spacing and information about the transmission cycle. For example, the first message may be used for scheduling data signals and second calibration signals at the upper network node (220).

[0135] In operation 1003, the lower network node (220) may receive a second message from the upper network node (220). For example, the second message may include scheduling information for data signals and calibration signals. For example, the second subcarrier spacing assigned to the calibration signals may be different from the first subcarrier spacing assigned to the data signals.

[0136] In operation 1004, the lower network node (220) may perform calibration using second calibration signals having a second subcarrier spacing based on scheduling information received from the upper network node (210).

[0137] Figure 11 shows an example of calibration performance.

[0138] Referring to FIG. 11, the horizontal axis of the chart (1100) and the chart (1110) represents the number of antennas, and the vertical axis represents the saving ratio (%) of the time interval to which calibration signals are allocated.

[0139] For example, the maximum reduction rate of the time interval to which calibration signals are allocated can be identified according to [Mathematical Formula 3] below.

[0140]

[0141]

[0142] For example, the minimum reduction rate of the time interval to which calibration signals are allocated can be identified according to [Mathematical Formula 4] below.

[0143]

[0144] In one embodiment, the maximum reduction rate of the time interval to which calibration signals are allocated can be identified according to [Mathematical Formula 4] below.

[0145]

[0146] Charts (1100) and (1110) of FIG. 11 show the time (or duration in the time domain) reduction rate of calibration signals compared to a 30 kHz subcarrier spacing.

[0147] For example, chart (1100) represents the maximum time saving ratio when allocating resources without considering the transmission time interval (TTI) (e.g., symbol-wise scheduling). For example, waveform (1101) represents the maximum time saving ratio of calibration signals with a 60 kHz subcarrier spacing. For example, waveform (1102) represents the maximum time saving ratio of calibration signals with a 120 kHz subcarrier spacing. For example, waveform (1103) represents the maximum time saving ratio of calibration signals with a 240 kHz subcarrier spacing. For example, waveform (1104) represents the maximum time saving ratio of calibration signals with a 480 kHz subcarrier spacing. For example, waveform (1105) represents the maximum time saving ratio of calibration signals with a 960 kHz subcarrier spacing. For example, the results of the waveforms (1101 to 1105) may be as shown in [Table 3] below.

[0148]

[0149] For example, chart (1100) represents the minimum time saving ratio when allocating resources considering TTI (e.g., slot-based scheduling). For example, waveform (1111) represents the minimum time saving ratio of calibration signals with a 60 kHz subcarrier spacing. For example, waveform (1112) represents the minimum time saving ratio of calibration signals with a 120 kHz subcarrier spacing. For example, waveform (1113) represents the minimum time saving ratio of calibration signals with a 240 kHz subcarrier spacing. For example, waveform (1114) represents the minimum time saving ratio of calibration signals with a 480 kHz subcarrier spacing. For example, waveform (1115) represents the minimum time saving ratio of calibration signals with a 960 kHz subcarrier spacing. For example, the results of waveforms (1111 to 1115) may be as shown in [Table 4] below.

[0150]

[0151] Referring to chart (1100), chart (1110), [Table 3], and [Table 4], as the subcarrier spacing of calibration signals increases according to the present disclosure, the time domain interval allocated for the calibration signals can be shortened. Therefore, the communication device can allocate more data signals to the time resource, thereby improving the data transmission rate.

[0152] The communication device according to the present disclosure can be less affected by the channel coherent time because it requires less calibration processing time. The communication device according to the present disclosure can dynamically control the subcarrier spacing (SCS) of calibration signals according to the coherent bandwidth of the hardware system channel. By controlling the subcarrier spacing of the calibration signals, the communication device according to the present disclosure can improve data transmission efficiency. The communication device according to the present disclosure can reduce the computational complexity for obtaining calibration information. The communication device according to the present disclosure uses a data transmission / reception circuit, so a separate calibration circuit is not required. Since the communication device according to the present disclosure does not require a separate calibration circuit, the complexity of the circuit configuration can be reduced.

[0153] The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary knowledge in the technical field to which the present disclosure pertains.

[0154] A communication device as described above may include an antenna array. The communication device may include a plurality of radio frequency (RF) processing circuits for the antenna array. The communication device may include a memory storing instructions and including one or more storage media. The communication device may include at least one processor including a processing circuit. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to transmit first calibration signals having a first subcarrier spacing (SCS) via a plurality of RF transmit paths of the plurality of RF processing circuits. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to obtain the first calibration signals via a plurality of RF receive paths of the plurality of RF processing circuits. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to identify a bandwidth in a frequency domain having an amplitude variation of the first calibration signals that is less than a first threshold value and a phase variation of the first calibration signals that is less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to perform calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among a plurality of SCSs. The second SCS may indicate a frequency interval of each of the OFDM symbols.The time interval of each of the above OFDM symbols may be inversely proportional to the second SCS.

[0155] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the communication device to obtain the second calibration signals via the plurality of RF receiving paths of the plurality of RF processing circuits. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to obtain first calibration information, based on the second calibration signals, the first calibration information including information about an amplitude variation and information about a phase variation of the second calibration signals in the first subchannels corresponding to the second SCS.

[0156] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the communication device to identify bandwidth information of second sub-channels based on a resolution factor and the first SCS of data signals. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to obtain second calibration information, including information about an amplitude variation and information about a phase variation of the second calibration signals in the second sub-channels, based on the bandwidth information and the first calibration information. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to correct the data signals based on the second calibration information.

[0157] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the communication device to identify, based on the amplitude information and the phase information of the first calibration signals, a duration in the time domain having an amplitude variation of the first calibration signals less than a third threshold value and a phase variation of the first calibration signals less than a fourth threshold value. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to identify a transmission periodicity of the second calibration signals based on the duration.

[0158] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the communication device to transmit a message to a distributed unit (DU) that includes information about the second SCS and information about a transmission period of the second calibration signals. The instructions, when individually or collectively executed by the at least one processor, may cause the communication device to receive, from the DU, scheduling information about the second calibration signals having the second SCS and scheduling information about data signals having the first SCS.

[0159] For example, the first SCS may be smaller than the second SCS. The symbol length of the second calibration signals may be shorter than the symbol length of the data signals having the first SCS.

[0160] For example, the second calibration signals may include a first signal and a second signal. The first signal may be transmitted through a first RF transmission path in a first OFDM symbol among the OFDM symbols. The second signal may be transmitted through a second RF transmission path in a second OFDM symbol different from the first OFDM symbol among the OFDM symbols. The first signal and the second signal may be received through a first RF reception path corresponding to the first RF transmission path. The first signal and the second signal may be received through a second RF reception path corresponding to the second RF transmission path.

[0161] A method performed by a communication device including a plurality of radio frequency (RF) processing circuits for an antenna array as described above may include transmitting first calibration signals having a first subcarrier spacing (SCS) through a plurality of RF transmission paths of the plurality of RF processing circuits. The method may include acquiring the first calibration signals through a plurality of RF reception paths of the plurality of RF processing circuits. The method may include identifying a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The method may include performing calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among the plurality of SCSs. The second SCS may indicate a frequency spacing of each of the OFDM symbols. The time interval of each of the above OFDM symbols may be inversely proportional to the second SCS.

[0162] For example, the method may include an operation of obtaining the second calibration signals through the plurality of RF receiving paths of the plurality of RF processing circuits. The method may include an operation of obtaining first calibration information including information about an amplitude change amount and information about a phase change amount of the second calibration signals in first sub-channels corresponding to the second SCS, based on the second calibration signals.

[0163] For example, the method may include an operation of identifying bandwidth information of second sub-channels based on a resolution factor and the first SCS of data signals. The method may include an operation of obtaining second calibration information including information on an amplitude variation amount and information on a phase variation amount of the second calibration signals in the second sub-channels based on the bandwidth information and the first calibration information. The method may include an operation of correcting the data signals based on the second calibration information.

[0164] For example, the method may include an operation of identifying a time period in a time domain having an amplitude variation of the first calibration signals less than a third threshold value and a phase variation of the first calibration signals less than a fourth threshold value, based on the amplitude information and the phase information of the first calibration signals. The method may include an operation of identifying a transmission periodicity of the second calibration signals according to the time period.

[0165] For example, the method may include transmitting a message to a distributed unit (DU) that includes information about the second SCS and information about a transmission period of the second calibration signals. The method may include receiving, from the DU, scheduling information about the second calibration signals having the second SCS and scheduling information about data signals having the first SCS.

[0166] For example, the first SCS may be smaller than the second SCS. The symbol length of the second calibration signals may be shorter than the symbol length of the data signals having the first SCS.

[0167] For example, the second calibration signals may include a first signal and a second signal. The first signal may be transmitted through a first RF transmission path in a first OFDM symbol among the OFDM symbols. The second signal may be transmitted through a second RF transmission path in a second OFDM symbol different from the first OFDM symbol among the OFDM symbols. The first signal and the second signal may be received through a first RF reception path corresponding to the first RF transmission path. The first signal and the second signal may be received through a second RF reception path corresponding to the second RF transmission path.

[0168] The non-transitory computer-readable storage medium as described above may include one or more programs. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to transmit first calibration signals having a first subcarrier spacing (SCS) via a plurality of RF transmit paths of the plurality of RF processing circuits. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to obtain the first calibration signals via a plurality of RF receive paths of the plurality of RF processing circuits. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to identify a bandwidth in a frequency domain having an amplitude variation of the first calibration signals that is less than a first threshold value and a phase variation of the first calibration signals that is less than a second threshold value, based on amplitude information and phase information of the first calibration signals. The one or more programs may include instructions that, when executed by at least one processor of the communication device, cause the communication device to perform calibration by transmitting second calibration signals in orthogonal frequency division multiplexing (OFDM) symbols according to a second SCS corresponding to a bandwidth of the frequency domain among a plurality of SCSs. The second SCS may represent a frequency interval of each of the OFDM symbols. A time interval of each of the OFDM symbols may be inversely proportional to the second SCS.

[0169] For example, the one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to obtain the second calibration signals via the plurality of RF receiving paths of the plurality of RF processing circuits. The one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to obtain first calibration information, based on the second calibration signals, the first calibration information including information about an amplitude variation amount and information about a phase variation amount of the second calibration signals in the first sub-channels corresponding to the second SCS.

[0170] For example, the one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to identify bandwidth information of second sub-channels based on a resolution factor and the first SCS of data signals. The one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to obtain second calibration information, the second calibration information including information about an amplitude variation amount and information about a phase variation amount of the second calibration signals in the second sub-channels, based on the bandwidth information and the first calibration information. The one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to correct the data signals based on the second calibration information.

[0171] For example, the one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to identify a duration in the time domain having an amplitude variation of the first calibration signals that is less than a third threshold value and a phase variation of the first calibration signals that is less than a fourth threshold value, based on the amplitude information and the phase information of the first calibration signals. The one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to identify a transmission periodicity of the second calibration signals according to the time period.

[0172] For example, the one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to transmit a message to a distributed unit (DU) that includes information about the second SCS and information about a transmission period of the second calibration signals. The one or more programs may include instructions that, when executed by the at least one processor of the communication device, cause the communication device to receive, from the DU, scheduling information about the second calibration signals having the second SCS and scheduling information about data signals having the first SCS.

[0173] For example, the first SCS may be smaller than the second SCS. A symbol length of the second calibration signals may be shorter than a symbol length of data signals having the first SCS. The second calibration signals may include a first signal and a second signal. The first signal may be transmitted through a first RF transmission path in a first OFDM symbol among the OFDM symbols. The second signal may be transmitted through a second RF transmission path in a second OFDM symbol different from the first OFDM symbol among the OFDM symbols. The first signal and the second signal may be received through a first RF reception path corresponding to the first RF transmission path. The first signal and the second signal may be received through a second RF reception path corresponding to the second RF transmission path.

[0174] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains.

[0175] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0176] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specifications of the present disclosure. The one or more programs may be provided as included in a computer program product. The computer program product may be traded between sellers and buyers as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read only memory (CD-ROM)) or an application store (e.g., Play Store). ™ ) or directly between two user devices (e.g., smart phones), online distribution (e.g., downloading or uploading). In the case of online distribution, at least a portion of the computer program product may be at least temporarily stored or temporarily created in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0177] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0178] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0179] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0180] According to embodiments, one or more of the components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0181] Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible within the scope of the present disclosure.

Claims

1. In communication devices, antenna array; A plurality of RF (radio frequency) processing circuits for the antenna array; A memory storing instructions and including one or more storage media; and At least one processor comprising a processing circuit, The above instructions, when individually or collectively executed by the at least one processor, cause the communication device to: Transmitting first calibration signals having a first SCS (subcarrier spacing) through a plurality of RF transmission paths of the plurality of RF processing circuits, Obtaining the first calibration signals through the plurality of RF receiving paths of the plurality of RF processing circuits, Based on the amplitude information and phase information of the first calibration signals, a bandwidth of a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value is identified, and Causing calibration to be performed by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among a plurality of SCSs, The above second SCS represents the frequency interval of each of the OFDM symbols, and The time interval of each of the above OFDM symbols is inversely proportional to the second SCS. Communication device.

2. In paragraph 1, The above instructions, when individually or collectively executed by the at least one processor, cause the communication device to: Obtaining the second calibration signals through the plurality of RF receiving paths of the plurality of RF processing circuits, and Based on the second calibration signals, first calibration information including information on amplitude variation and information on phase variation of the second calibration signals in first sub-channels corresponding to the second SCS is obtained. Communication device.

3. In paragraph 2, The above instructions, when individually or collectively executed by the at least one processor, cause the communication device to: Based on the resolution factor and the first SCS of the data signals, the bandwidth information of the second sub-channels is identified, Based on the bandwidth information and the first calibration information, second calibration information including information on amplitude variation and phase variation of the second calibration signals in the second sub-channels is obtained, and Causing the data signals to be corrected based on the second calibration information, Communication device.

4. In paragraph 1, The above instructions, when individually or collectively executed by the at least one processor, cause the communication device to: Based on the amplitude information and the phase information of the first calibration signals, a time interval (duration) in the time domain is identified having an amplitude change amount of the first calibration signals less than a third threshold value and a phase change amount of the first calibration signals less than a fourth threshold value, causing the transmission periodicity of the second calibration signals to be identified according to the above time interval, Communication device.

5. In paragraph 1, The above instructions, when individually or collectively executed by the at least one processor, cause the communication device to: Transmitting a message including information about the second SCS and information about the transmission cycle of the second calibration signals to a DU (distributed unit), and Causing the DU to receive scheduling information for the second calibration signals having the second SCS and scheduling information for data signals having the first SCS. Communication device.

6. In paragraph 1, The above first SCS is smaller than the above second SCS, The symbol length of the second calibration signals is shorter than the symbol length of the data signals having the first SCS. Communication device.

7. In paragraph 1, The second calibration signals include a first signal and a second signal, The first signal is transmitted through a first RF transmission path in a first OFDM symbol among the OFDM symbols, The second signal is transmitted through a second RF transmission path in a second OFDM symbol different from the first OFDM symbol among the OFDM symbols, The first signal and the second signal are received through a first RF receiving path corresponding to the first RF transmitting path, and The first signal and the second signal are received through a second RF receiving path corresponding to the second RF transmitting path. Communication device.

8. A method performed by a communication device including a plurality of RF (radio frequency) processing circuits for an antenna array, An operation of transmitting first calibration signals having a first subcarrier spacing (SCS) through a plurality of RF transmission paths of the plurality of RF processing circuits; An operation of acquiring the first calibration signals through a plurality of RF receiving paths of the plurality of RF processing circuits; An operation of identifying a bandwidth in a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value, based on amplitude information and phase information of the first calibration signals; An operation of performing calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among a plurality of SCSs, The above second SCS represents the frequency interval of each of the OFDM symbols, and The time interval of each of the above OFDM symbols is inversely proportional to the second SCS. method.

9. In paragraph 8, An operation of acquiring the second calibration signals through the plurality of RF receiving paths of the plurality of RF processing circuits; and Further comprising an operation of obtaining first calibration information including information on an amplitude change amount and information on a phase change amount of the second calibration signals in first sub-channels corresponding to the second SCS, based on the second calibration signals. method.

10. In paragraph 9, An operation of identifying bandwidth information of second sub-channels based on the first SCS of the resolution factor and data signals; An operation of obtaining second calibration information including information on amplitude variation and phase variation of the second calibration signals in the second sub-channels based on the bandwidth information and the first calibration information; and Further comprising an operation of correcting the data signals based on the second calibration information. method.

11. In paragraph 8, An operation of identifying a time interval (duration) in a time domain having an amplitude change amount of the first calibration signals less than a third threshold value and a phase change amount of the first calibration signals less than a fourth threshold value based on the amplitude information and the phase information of the first calibration signals; and Further comprising an operation of identifying a transmission periodicity of the second calibration signals according to the time interval. method.

12. In paragraph 8, An operation of transmitting a message including information about the second SCS and information about the transmission cycle of the second calibration signals to a DU (distributed unit); and Further comprising an operation of receiving scheduling information for the second calibration signals having the second SCS and scheduling information for data signals having the first SCS from the DU. method.

13. In paragraph 8, The above first SCS is smaller than the above second SCS, The symbol length of the second calibration signals is shorter than the symbol length of the data signals having the first SCS. method.

14. In paragraph 8, The second calibration signals include a first signal and a second signal, The first signal is transmitted through a first RF transmission path in a first OFDM symbol among the OFDM symbols, The second signal is transmitted through a second RF transmission path in a second OFDM symbol different from the first OFDM symbol among the OFDM symbols, The first signal and the second signal are received through a first RF receiving path corresponding to the first RF transmitting path, and The first signal and the second signal are received through a second RF receiving path corresponding to the second RF transmitting path. method.

15. A non-transitory computer-readable storage medium containing one or more programs, wherein the one or more programs, when executed by at least one processor of a communication device, Transmitting first calibration signals having a first SCS (subcarrier spacing) through a plurality of RF transmission paths of the plurality of RF processing circuits, Obtaining the first calibration signals through the plurality of RF receiving paths of the plurality of RF processing circuits, Based on the amplitude information and phase information of the first calibration signals, a bandwidth of a frequency domain having an amplitude variation of the first calibration signals less than a first threshold value and a phase variation of the first calibration signals less than a second threshold value is identified, Instructions for causing the communication device to perform calibration by transmitting second calibration signals in OFDM (orthogonal frequency division multiplexing) symbols according to a second SCS corresponding to the bandwidth of the frequency domain among a plurality of SCSs, The above second SCS represents the frequency interval of each of the OFDM symbols, and The time interval of each of the above OFDM symbols is inversely proportional to the second SCS. Non-transitory computer-readable storage medium.

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