Electronic device and method for identifying frequency offset of random access signal in wireless communication system

Abstract

According to an embodiment, a method performed by an electronic device may comprise an operation of acquiring, on the basis of a physical random access channel (PRACH) region, a preamble signal related to signals received via a plurality of antennas. The method may comprise an operation of acquiring delay information for the preamble signal. The method may comprise an operation of acquiring energy information, acquired through a correlation operation, about the preamble signal. The method may comprise an operation of estimating a frequency offset for the preamble signal on the basis of the delay information and the energy information. The method may comprise an operation of compensating for the estimated frequency offset for a received data signal on the basis of a physical uplink shared channel (PUSCH) region.

Description

Electronic device and method for identifying frequency offset of random access signal in wireless communication system

[0001] The present disclosure relates to a wireless communication system. More specifically, the present disclosure relates to an electronic device and method for identifying a frequency offset of a random access signal in a wireless communication system.

[0002] In a wireless communication system, a terminal can transmit a random access signal to a base station to connect to the base station. The base station can then perform a random access process with the terminal based on the random access signal. In the random access signal, a subcarrier spacing equal to or smaller than the subcarrier spacing used in the uplink channel can be used to support wide cell coverage.

[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] According to one embodiment, an electronic device may include a transceiver, at least one processor including processing circuitry, and one or more storage media, and a memory storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain a preamble signal associated with signals received through a plurality of antennas based on a physical random access channel (PRACH) region. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain delay information for the preamble signal. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain energy information of the preamble signal obtained through a correlation operation. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to estimate a frequency offset for the preamble signal based on the delay information and the energy information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compensate for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0005] According to one embodiment, a method performed by an electronic device may include an operation of obtaining a preamble signal related to signals received through a plurality of antennas based on a physical random access channel (PRACH) region. The method may include an operation of obtaining delay information for the preamble signal. The method may include an operation of obtaining energy information of the preamble signal obtained through a correlation operation. The method may include an operation of estimating a frequency offset for the preamble signal based on the delay information and the energy information. The method may include an operation of compensating for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0006] According to one embodiment, a non-transitory computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed by a processor of an electronic device, cause the electronic device to obtain a preamble signal associated with signals received via a plurality of antennas based on a physical random access channel (PRACH) region. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to obtain delay information for the preamble signal. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to obtain energy information of the preamble signal obtained through a correlation operation. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to estimate a frequency offset for the preamble signal based on the delay information and the energy information. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to compensate for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0007] Figure 1 illustrates a wireless communication system.

[0008] Figure 2a illustrates a front-hole interface.

[0009] Figure 2b illustrates the fronthaul interface of an O(open)-RAN(radio access network).

[0010] Figure 3a illustrates the functional configuration of a distributed unit (DU).

[0011] Figure 3b illustrates the functional configuration of a RU (radio unit).

[0012] Figure 4 illustrates an example of function split between DU and RU.

[0013] Figure 5 illustrates an example of a time-frequency domain resource structure supported by a wireless communication system.

[0014] Figure 6 illustrates examples of channels in a communication standard.

[0015] Figure 7 shows an example of the structure of a random access signal.

[0016] Figure 8 shows an example of a PRACH detector.

[0017] Figure 9 shows an example of a frequency offset estimation unit of a PRACH detector.

[0018] Figure 10 shows examples of graphs for estimating frequency offset.

[0019] Figure 11 illustrates a flowchart regarding the operation of an electronic device.

[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., signal, information, message, signaling), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms for operational states (e.g., step, operation, procedure), terms referring to data (e.g., packet, user stream, information, bit, symbol, codeword), terms referring to channels, terms referring to network entities, terms referring to components of devices, etc. are examples for convenience of description. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[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 the present disclosure describes various embodiments using terms used in some communication standards (e.g., 3rd Generation Partnership Project (3GPP), extensible radio access network (xRAN), open-radio access network (O-RAN), etc.), these are merely examples for explanation. The various embodiments of the present disclosure can be easily modified and applied to other communication systems.

[0025] Figure 1 illustrates 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. According to one embodiment, the terminal (120) is a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, according to one embodiment, 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 information element (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 decreases, 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 expanded examples of base stations according to various embodiments of the present disclosure are described through FIGS. 2A and 2B.

[0035] FIG. 2A illustrates a fronthaul interface. Unlike the backhaul between a base station and a core network, fronthaul refers to the connection between entities between a wireless LAN and a base station. FIG. 2A illustrates an example of a fronthaul structure between a DU (210) and one RU (220), but this is merely for convenience of explanation and the present disclosure is not limited thereto. In other words, embodiments of the present disclosure can also be applied to a fronthaul structure between one DU and multiple RUs. For example, embodiments of the present disclosure can be applied to a fronthaul structure between one DU and two RUs. Furthermore, embodiments of the present disclosure can also be applied to a fronthaul structure between one DU and three RUs.

[0036] Referring to FIG. 2A, a base station (110) may include a DU (210) and an RU (220). A fronthaul (215) between the DU (210) and the RU (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.

[0037] As communications technology advances, mobile data traffic increases, significantly increasing the bandwidth requirements for the fronthaul between the digital unit and the radio unit. In deployments such as C-RAN (centralized / cloud radio access network), the DU performs functions for the packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical layer (PHY), while the RU can be implemented to perform additional functions for the PHY layer in addition to its radio frequency (RF) functions.

[0038] DU (210) may be responsible for upper layer functions of a wireless network. For example, DU (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, if DU (210) complies with the O-RAN standard, it may be referred to as O-DU (O-RAN DU). DU (210) may be replaced with a first network entity for a base station (e.g., gNB) in embodiments of the present disclosure, if necessary.

[0039] The RU (220) may be responsible for lower layer functions of a wireless network. For example, the RU (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 DU (210), and may include, for example, inverse fast Fourier transform (iFFT) transform (or fast Fourier transform (FFT) transform), cyclic prefix (CP) insertion (CP removal), and digital beamforming. An example of such specific functional separation is described in detail in FIG. 4. The RU (220) may be referred to as an 'access unit (AU)', an 'access point (AP)', a 'transmission / reception point (TRP)', a 'remote radio head (RRH)', a 'radio unit (RU)', or other terms having an equivalent technical meaning thereto. In one embodiment, if RU (220) complies with the O-RAN standard, it may be referred to as O-RU (O-RAN RU). RU (220) may be replaced with a second network entity for a base station (e.g., gNB) in embodiments of the present disclosure, if necessary.

[0040] Although FIG. 2A illustrates that the base station (110) includes a DU (210) and a RU (220), the embodiments of the present disclosure are not limited thereto. The 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. In this case, the distributed unit (DU) may include the digital unit (DU) and radio unit (RU) of FIG. 1. 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 CU and DU (distributed unit) can be referred to as the F1 interface.

[0041] A centralized unit (CU) can be connected to one or more DUs and can be responsible for functions at a higher layer than the DU. For example, the CU can be responsible for functions at the radio resource control (RRC) and packet data convergence protocol (PDCP) layers, while the DU and RU can be responsible for functions at lower layers. The DU can perform some functions (high PHY) of the radio link control (RLC), media access control (MAC), and physical (PHY) layers, while the RU can be responsible for the remaining functions (low PHY) of the PHY layer. In addition, for example, a digital unit (DU) can be included in a distributed unit (DU) depending on the implementation of a distributed deployment of the base station. Hereinafter, unless otherwise defined, the operations of DU (digital unit) and RU are described, but various embodiments of the present disclosure can be applied to both a base station deployment including CU and a deployment in which DU is directly connected to the core network (i.e., a base station in which CU and DU are integrated as a single entity (e.g., NG-RAN node)).

[0042] Figure 2b illustrates the fronthaul interface of an open RAN (radio access network). A base station (110) according to a distributed deployment is exemplified as an eNB or gNB.

[0043] Referring to FIG. 2b, the base station (110) may include an O-DU (251) and O-RUs (253-1, ..., 253-n). Hereinafter, for convenience of explanation, the operation and function of the O-RU (253-1) may be understood as a description of each of the other O-RUs (e.g., O-RU (253-n)).

[0044] The O-DU (251) is a logical node that includes functions, excluding functions exclusively assigned to the O-RU (253-1), among the functions of a base station (e.g., eNB, gNB) according to FIG. 4 described below. The O-DU (251) can control the operation of the O-RUs (253-1, ..., 253-n). The O-DU (251) may be referred to as an LLS (lower layer split) CU (central unit). The O-RU (253-1) is a logical node that includes a subset of the functions of a base station (e.g., eNB, gNB) according to FIG. 4 described below. Real-time aspects of control plane (C-plane) communication and user plane (U-plane) communication with the O-RU (253-1) can be controlled by the O-DU (251).

[0045] The O-DU (251) can communicate with the O-RU (253-1) through an LLS interface. The LLS interface corresponds to a fronthaul interface. The LLS interface refers to a logical interface between the O-DU (251) and the O-RU (253-1) that utilizes lower layer functional split (i.e., intra-PHY based functional split). The LLS-C between the O-DU (251) and the O-RU (253-1) provides the C-plane through the LLS interface. The LLS-U between the O-DU (251) and the O-RU (253-1) provides the U-plane through the LLS interface.

[0046] In FIG. 2B, to explain the O-RAN, entities of the base station (110) are described as O-DU and O-RU. However, these names are not to be construed as limiting the embodiments of the present disclosure. In the embodiments described below, it is obvious that the operations of the DU (210) can be performed by the O-DU (251). The description of the DU (210) can be applied to the O-DU (251). Similarly, in the embodiments described below, it is obvious that the operations of the RU (220) can be performed by the O-RU (253-1). The description of the RU (220) can be applied to the O-DU (253-1).

[0047] Fig. 3a illustrates the functional configuration of a DU (distributed unit). The configuration illustrated in Fig. 3a can be understood as the configuration of the DU (210) of Fig. 2a (or the O-DU (250) of Fig. 2b) 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, and this can be implemented by hardware, software, or a combination of hardware and software.

[0048] Referring to FIG. 3a, DU (210) includes a transceiver (310), memory (320), and processor (330).

[0049] 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 via a transmission medium (e.g., copper wire, optical fiber). 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 DU (210) can communicate with a radio unit (RU) via the transceiver (310). The DU (210) can be connected to a core network or a CU in a distributed arrangement via the transceiver (310).

[0050] 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) generates complex symbols by encoding and modulating the transmitted bit stream. Furthermore, when receiving data, the transceiver (310) restores the received bit stream by demodulating and decoding the baseband signal. Furthermore, the transceiver (310) may include multiple transmission and reception paths. Furthermore, according to one embodiment, the transceiver (310) may be connected to the core network or other nodes (e.g., an integrated access backhaul (IAB)).

[0051] 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 transmit 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 only the transceiver (310) is illustrated in FIG. 3A, in other implementations, the DU (210) may include two or more transceivers.

[0052] The transceiver (310) transmits and receives 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 are used to mean that the transceiver (310) performs the processing described above.

[0053] 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. The backhaul transceiver provides an interface for communicating with other nodes within the network. That is, the backhaul transceiver converts 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 converts a physical signal received from other nodes into a bit stream.

[0054] The memory (320) stores data such as basic programs, application programs, and setting information for the operation of the DU (210). The memory (320) may be referred to as a storage unit. The memory (320) may be composed of volatile memory, nonvolatile memory, or a combination of volatile memory and nonvolatile memory. In addition, the memory (320) provides stored data upon request from the processor (330).

[0055] The processor (330) controls the overall operations of the DU (210). The processor (380) may be referred to as a control unit. For example, the processor (330) transmits and receives signals through the transceiver (310) (or through the backhaul communication unit). In addition, the processor (330) records and reads data from the memory (320). In addition, the processor (330) may perform the functions of the protocol stack required by the communication standard. Although only the processor (330) is illustrated in FIG. 3A, the DU (210) may include two or more processors according to other implementation examples.

[0056] The configuration of DU (210) illustrated in FIG. 3A is merely an example, and examples of DUs 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.

[0057] Fig. 3b illustrates the functional configuration of a radio unit (RU). The configuration illustrated in Fig. 3b can be understood as a configuration of the RU (220) of Fig. 2b or the O-RU (253-1) of Fig. 2b 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, and this can be implemented by hardware, software, or a combination of hardware and software.

[0058] Referring to FIG. 3b, the RU (220) includes an RF transceiver (360), a fronthaul transceiver (365), a memory (370), and a processor (380).

[0059] The RF transceiver (360) performs functions for transmitting and receiving signals via a wireless channel. For example, the RF transceiver (360) upconverts a baseband signal into an RF band signal and transmits it via an antenna, and downconverts an RF band signal received via the antenna into a baseband signal. For example, the RF transceiver (360) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

[0060] The RF transceiver (360) may include multiple transmission and reception paths. Furthermore, the RF transceiver (360) may include an antenna unit. The RF transceiver (360) may include at least one antenna array composed of multiple antenna elements. 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)). Here, the digital circuits and analog circuits may be implemented in a single package. In addition, the RF transceiver (360) may include multiple RF chains. The RF transceiver (360) may perform beamforming. The RF transceiver (360) may apply beamforming weights to a signal to be transmitted and received in order to impart directionality according to the settings of the processor (380). According to one embodiment, the RF transceiver (360) may include a radio frequency (RF) block (or RF section).

[0061] According to one embodiment, 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. 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., a MIB, a SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data. In addition, for example, the RF transceiver (360) can receive an uplink signal. 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 only the RF transceiver (360) is illustrated in FIG. 3b, in other implementation examples, the RU (220) may include two or more RF transceivers.

[0062] According to embodiments, the RF transceiver (460) may transmit a RIM-RS. The RF transceiver (460) may transmit a first type of RIM-RS (e.g., RIM-RS type 1 of 3GPP) to indicate the detection of far-field interference. The RF transceiver (460) may transmit a second type of RIM-RS (e.g., RIM-RS type 2 of 3GPP) to indicate the presence or absence of far-field interference.

[0063] The fronthaul transceiver (365) can transmit and receive signals. According to one embodiment, the fronthaul transceiver (365) can transmit and receive signals on the fronthaul interface. For example, the fronthaul transceiver (365) can receive a management plane (M-plane) message. For example, the fronthaul transceiver (365) can receive a synchronization plane (S-plane) message. For example, the fronthaul transceiver (365) can receive a control plane (C-plane) message. For example, the fronthaul transceiver (365) can transmit a user plane (U-plane) message. For example, the fronthaul transceiver (365) can receive a user plane message. Although only the fronthaul transceiver (365) is shown in FIG. 3b, according to other implementation examples, the RU (220) may include two or more fronthaul transceivers.

[0064] The RF transceiver (360) and the fronthaul transceiver (365) 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 unit', a 'receiver unit', or a 'transmitter-receiver unit'. In addition, in the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the RF transceiver (360). In the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the RF transceiver (360).

[0065] The memory (370) stores data such as basic programs, application programs, and setting information for the operation of the RU (220). The memory (370) may be referred to as a storage unit. The memory (370) may be configured as volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. In addition, the memory (370) provides the stored data according to a request from the processor (380). According to one embodiment, the memory (370) may include a memory for conditions, commands, or setting values ​​related to the SRS transmission method.

[0066] The processor (380) controls the overall operations of the RU (220). The processor (380) may be referred to as a control unit. For example, the processor (380) transmits and receives signals through the RF transceiver (360) or the fronthaul transceiver (365). In addition, the processor (380) records and reads data in the memory (370). In addition, the processor (380) may perform functions of a protocol stack required by a communication standard. Although only the processor (380) is illustrated in FIG. 3B, the RU (220) may include two or more processors according to other implementation examples. 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). Additionally, the processor (380) may include various modules for performing communication. The processor (380) may control the RU (220) to perform operations according to the embodiments described below.

[0067] The configuration of RU (220) illustrated in FIG. 3b is merely an example, and examples of RUs 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.

[0068] Figure 4 illustrates an example of function split between DUs and RUs. As wireless communication technologies advance (e.g., the introduction of 5G (5th generation) communication systems (or NR (new radio) communication systems), the frequency bands used have increased further. As the cell radius of a base station has become significantly smaller, the number of RUs required for installation has also increased further. Furthermore, in 5G communication systems, the amount of data transmitted has increased by a factor of up to ten, significantly increasing the transmission capacity of the wired network transmitted to the fronthaul. Due to the factors described above, the installation cost of the wired network in the 5G communication system may increase significantly. Therefore, in order to lower the transmission capacity of the wired network and reduce the installation cost of the wired network, 'function split' can be utilized, which transfers some of the functions of the modem of the DU to the RU to lower the transmission capacity of the fronthaul.

[0069] To reduce the burden on the DU, the role of the RU, which is traditionally solely responsible for RF functions, can be expanded to include some physical layer functions. As the RU performs higher-layer functions, its throughput increases, which can increase transmission bandwidth in the fronthaul while reducing latency requirements due to response processing. However, as the RU performs higher-layer functions, virtualization gains decrease, and the RU's size, weight, and cost increase. Considering the trade-offs between the advantages and disadvantages described above, implementing an optimal functional separation is required.

[0070] Referring to Figure 4, the functional separation in the physical layer below the MAC layer is illustrated. For the downlink (DL) that transmits a signal to a terminal through a wireless network, the base station can sequentially perform channel encoding / scrambling, modulation, layer mapping, antenna mapping, RE mapping, digital beamforming (e.g., precoding), iFFT transform / CP insertion, and RF transform. For the uplink (UL) that receives a signal from a terminal through a wireless network, the base station can sequentially perform RF transform, FFT transform / CP removal, digital beamforming (pre-combining), RE demapping, channel estimation, layer demapping, demodulation, and decoding / descrambling. The separation of uplink and downlink functions can be defined in various types depending on the needs of vendors, discussions in standards, etc., according to the above-mentioned trade-offs.

[0071] In the first functional separation (405), the RU performs the RF function, and the DU performs the PHY function. The first functional separation is one in which the PHY function is not substantially implemented in the RU, and may be referred to as Option 8, for example. In the second functional separation (410), the RU performs iFFT conversion / CP insertion in the DL and FFT conversion / CP removal in the UL of the PHY function, and the DU performs the remaining PHY functions. As an example, the second functional separation (410) may be referred to as Option 7-1. In the third functional separation (420a), the RU performs iFFT conversion / CP insertion in the DL and FFT conversion / CP removal and digital beamforming in the UL of the PHY function, and the DU performs the remaining PHY functions. As an example, the third functional separation (420a) may be referred to as Option 7-2x Category A. In the fourth functional separation (420b), the RU performs up to digital beamforming in both the DL and UL, and the DU performs upper PHY functions after the digital beamforming. For example, the fourth functional separation (420b) may be referred to as Option 7-2x Category B. In the fifth functional separation (425), the RU performs up to RE mapping (or RE demapping) in both the DL and UL, and the DU performs upper PHY functions after RE mapping (or RE demapping). For example, the fifth functional separation (425) may be referred to as Option 7-2. In the sixth functional separation (430), the RU performs up to modulation (or demodulation) in both the DL and UL, and the DU performs upper PHY functions after modulation (or demodulation). For example, the sixth functional separation (430) may be referred to as Option 7-3. In the seventh functional separation (440), the RU performs encoding / scrambling (or decoding / descrambling) in both the DL and UL, and the DU performs subsequent upper PHY functions up to modulation (or demodulation). For example, the seventh functional separation (440) may be referred to as Option 6.

[0072] In one embodiment, when a large amount of signal processing is expected, such as in the FR 1 MMU, functional separation at a relatively high layer (e.g., the fourth functional separation (420b)) may be required to reduce fronthaul capacity. In addition, functional separation at too high a layer (e.g., the sixth functional separation (430)) may complicate the control interface and cause a burden on the implementation of the RU due to the inclusion of a large number of PHY processing blocks within the RU. Therefore, appropriate functional separation may be required depending on the arrangement and implementation method of the DU and the RU.

[0073] In one embodiment, if the precoding of data received from the DU cannot be processed (i.e., if the precoding capability of the RU is limited), the third functional separation (420a) or a lower functional separation (e.g., the second functional separation (410)) may be applied. Conversely, if the DU has the capability to process the precoding of data received from the DU, the fourth functional separation (420b) or a higher functional separation (e.g., the sixth functional separation (430)) may be applied.

[0074] Hereinafter, embodiments in the present disclosure are described based on the third functional separation (420a) (which may be referred to as category A (CAT-A)) or the fourth functional separation (420b) (which may be referred to as category B (CAT-B)) for performing beamforming processing in an RU unless otherwise specified. The O-RAN standard distinguishes the types of O-RUs depending on whether the precoding function is located at the interface of the O-DU or the O-RU interface. An O-RU that does not perform precoding (i.e., has low complexity) may be referred to as a CAT-A O-RU. An O-RU that performs precoding may be referred to as a CAT-B O-RU.

[0075] Hereinafter, the term "upper-PHY" refers to physical layer processing handled in the DU of the fronthaul interface. For example, the upper-PHY may include FEC encoding / decoding, scrambling, and modulation / demodulation. Hereinafter, the term "lower-PHY" refers to physical layer processing handled in the RU of the fronthaul interface. For example, the lower-PHY may include FFT / iFFT, digital beamforming, PRACH (physical random access channel) extraction, and filtering. However, the above-described criteria do not exclude embodiments through other functional separations. The functional configuration, signaling, or operation of the embodiments described below may be applied not only to the third functional separation (420a) or the fourth functional separation (420b), but also to other functional separations.

[0076] Embodiments of the present disclosure exemplarily describe the standards of eCPRI and O-RAN as fronthaul interfaces when transmitting messages between a DU (e.g., DU (210) of FIG. 2a) and an RU (e.g., RU (220) of FIG. 2a). The Ethernet payload of the message may include an eCPRI header, an O-RAN header, and additional fields. Hereinafter, various embodiments of the present disclosure are described using standard terms of eCPRI or O-RAN, but other expressions having equivalent meanings to each term may be used instead in various embodiments of the present disclosure. Hereinafter, various embodiments of the present disclosure are described using standard terms of eCPRI or O-RAN, but are not limited thereto. For example, in various embodiments of the present disclosure, the CPRI standard may be used as the fronthaul interface.

[0077] The fronthaul transport protocol can use Ethernet and eCPRI, which are easy to share with networks. The Ethernet payload can include an eCPRI header and an O-RAN header. The eCPRI header can be located at the beginning of the Ethernet payload. The contents of the eCPRI header are as follows.

[0078] 1) ecpriVersion (4 bits): This parameter indicates the eCPRI protocol version.

[0079] 2) ecpriReserved (3 bits): This parameter is reserved for further use by eCPRI.

[0080] 3) ecpriConcatenation (1 bit): This parameter indicates when eCPRI concatenation is in use.

[0081] 4) ecpriMessage (1 byte): This parameter indicates the type of service carried by the message type. For example, the parameter indicates an IQ data message, a real-time control data message, or a transmission network delay measurement message.

[0082] 5) ecpriPayload (2 bytes): This parameter indicates the byte size of the payload portion of the eCPRI message.

[0083] 6) ecpriRtcid / ecpriPcid (2 bytes): This parameter is the eAxC (extended antenna-carrier) identifier (eAxC ID) and identifies a specific data flow associated with each C-plane (ecpriRtcid) or U-plane (ecpriPcid) message.

[0084] 7) ecpriSeqid (2 bytes): This parameter provides unique message identification and ordering at both levels. The first octet of this parameter is a sequence ID used to identify the order of messages within the eAxC message stream. The sequence ID is used to ensure that all messages are received and to reorder out-of-order messages. The second octet of this parameter is a subsequence ID. The subsequence ID is used to ensure ordering and implement reordering when radio-transport-level (eCPRI or IEEE-1914.3) fragmentation occurs.

[0085] The eAxC identifier (ID) includes a band and sector identifier ('BandSector_ID'), a component carrier identifier ('CC_ID'), a spatial stream identifier ('RU_Port_ID'), and a distributed unit identifier ('DU_Port_ID'). The bit allocation of the eAxC ID can be distinguished as follows.

[0086] 1) DU_port ID: The DU_port ID is used to distinguish processing units (e.g., different baseband cards) in the O-DU. The O-DU is expected to allocate bits for the DU_port ID, and the O-RU is expected to append the same value to the UL U-plane message carrying the same sectionId data.

[0087] 2) BandSector_ID: Aggregated cell identifier (band and sector distinction supported by O-RU).

[0088] 3) CC_ID: CC_ID identifies the carrier component supported by the O-RU.

[0089] 4) RU_port ID: The RU_port ID specifies logical flows such as data layer or spatial streams, and signaling channels that require separate numerologies (e.g. PRACH) or special antenna allocation such as SRS.

[0090] The application protocol of the fronthaul may include a control plane (C-plane), a user plane (U-plane), a synchronization plane (S-plane), and a management plane (M-plane).

[0091] The control plane may be configured to provide scheduling information and beamforming information via control messages. The control plane refers to real-time control between DUs and RUs. The user plane may include IQ sample data transmitted between DUs and RUs. The user plane may include user downlink data (IQ data or SSB / RS), uplink data (IQ data or SRS / RS), or PRACH data. A weight vector of the beamforming information described above may be multiplied by the user's data. The synchronization plane generally refers to traffic between DUs and RUs for a synchronization controller (e.g., IEEE grand master). The synchronization plane may be related to timing and synchronization. The management plane refers to non-real-time control between DUs and RUs. The management plane may be related to initial setup, non-realtime reset or reset, and non-realtime report.

[0092] Control plane messages, or C-plane messages, can be encapsulated based on a two-layer header approach. The first layer can consist of the eCPRI common header or the IEEE 1914.3 common header, which contains fields used to indicate the message type. The second layer is the application layer, which contains fields necessary for control and synchronization. Within the application layer, sections define the characteristics of U-plane data transmitted or received on a beam with a single pattern ID. The following section types are supported within the C-plane:

[0093] Section Type can indicate the purpose of control messages transmitted on the control plane. For example, the purposes of each Section Type are as follows.

[0094] 1) sectionType=0: Used to indicate resource blocks or symbols not used in DL or UL.

[0095] 2) sectionType=1: Used for most DL / UL wireless channels. Here, "most" refers to channels that do not require time or frequency offsets, such as those required for mixed numerology channels.

[0096] 3) sectionType=2: reserved for further use

[0097] 4) sectionType=3: PRACH and mixed-numerology channels. Channels that require a time or frequency offset or differ from the nominal SCS value(s).

[0098] 5) sectionType=4: reserved for further use

[0099] 6) sectionType=5: UE scheduling information. Transmits UE scheduling information so that the RU can perform real-time BF weight calculations (O-RAN optional BF method).

[0100] 7) sectionType=6: Transmits UE-specific channel information. Periodically transmits UE channel information to enable the RU to perform real-time BF weight calculations (O-RAN optional BF method).

[0101] 8) sectionType=7: Used for LAA support

[0102] Figure 5 illustrates an example of a time-frequency domain resource structure supported by a wireless communication system. Figure 5 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 in a 5G NR system to which the present embodiment can be applied.

[0103] Referring to Figure 5, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N symbOFDM symbols (502) are grouped to form one slot (506). Referring to FIG. 4, in a wireless communication system to which the present invention is applied, one radio frame (514) can be defined as having a length of 10 ms, which is composed of 10 subframes having the same length of 1 ms. In addition, one radio frame (514) can be divided into half-frames of 5 ms, and each half-frame includes 5 subframes. In FIG. 5, a slot (506) is composed of 14 OFDM symbols, but the length of a slot may vary depending on the subcarrier spacing. For example, in the case of numerologies having a 15 kHz subcarrier spacing, a slot is composed of a length of 1 ms, which is the same length as a subframe. In contrast, for numerators with a 30 kHz subcarrier spacing, a slot consists of 14 OFDM symbols, but two slots can be included in one subframe with a length of 0.5 ms.

[0104] That is, subframes and frames are defined with fixed time lengths, and slots are defined with the number of symbols, so that the time length can vary depending on the subcarrier spacing. Referring again to FIG. 5, radio resources supported by a wireless communication system are composed of multiple time resources, which are symbols, and multiple frequency resources, which are subcarriers, and each time resource and frequency resource can be expressed as a two-dimensional resource grid. In FIG. 5, a square, which is the smallest physical resource composed of one subcarrier and one symbol within the resource grid, is called a Resource Element (RE) (512).

[0105] In a wireless communication system to which the invention proposed in this specification can be applied, the minimum transmission unit in the frequency domain is a subcarrier, and the carrier bandwidth constituting the resource grid is N BW It consists of a number of subcarriers (504).

[0106] The basic unit of resources in the time-frequency domain is a resource element (hereinafter referred to as 'RE') (512), which can be represented by an OFDM symbol index and a subcarrier index. A resource block (508) can include a plurality of resource elements (512). In a wireless communication system to which the invention proposed in this specification can be applied, a resource block (508) (or physical resource block (hereinafter referred to as 'PRB')) is N in the time domain. symb N consecutive OFDM symbols and frequency domain SC RB can be defined as N consecutive subcarriers. In an NR system, a resource block (RB) (508) is defined as N in the frequency domain. SC RB can be defined as a series of consecutive subcarriers (510). One RB (508) is N in the frequency axis. SC RB Contains RE(512) of the dog.

[0107] In general, the minimum transmission unit of data is RB and the number of subcarriers is N. SC RB=12. The frequency domain may include common resource blocks (CRBs). Physical resource blocks (PRBs) may be defined in the bandwidth part (BWP) of the frequency domain. The CRB and PRB numbers may be determined based on the subcarrier spacing. The data rate may increase in proportion to the number of RBs scheduled to the terminal.

[0108] In NR systems, in the case of frequency division duplex (FDD) systems that operate downlink and uplink by frequency division, the downlink transmission bandwidth and 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 (e.g., frequency range (FR) 1 (510 MHz to 7125 MHz)) lower than the upper limit defined in the standard (e.g., 7.125) GHz. And [Table 2] shows some of the correspondences between transmission bandwidth, subcarrier spacing, and channel bandwidth defined in NR system in frequency bands higher than the lower limit defined in the specification (e.g., 24.25 GHz) (e.g., FR2 (24250 MHz - 52600 MHz) or FR2-2 (52600 MHz ~ 71000 MHz)). For example, an NR system with 100 MHz channel bandwidth with 30 kHz subcarrier spacing has a transmission bandwidth composed of 273 RBs. In [Table 1] and [Table 2], N / A may be a bandwidth-subcarrier combination not supported by the NR system.

[0109] Channel bandwidth [MHz] SCS 5 10 20 50 80 100 Transmission bandwidth configuration NRB 15kHz2552106207N / AN / A30kHz11245113321727360kHzN / A112465107135

[0110]

[0111] Figure 6 illustrates examples of channels in a communication standard.

[0112] Figure 6 illustrates examples of channels in a communication standard. The channels may include a physical channel (610), a transport channel (620), and a logical channel (630), depending on the layers defined in the communication standard.

[0113] Referring to FIG. 6, a physical channel (610) may provide functions (e.g., channel coding, HARQ processing, modulation, multi-antenna processing, resource mapping) necessary for generating physical signals at the physical layer. At the physical layer, physical signals are modulated using OFDM and may be transmitted in a wireless environment via time-frequency resources (e.g., resources of the resource grid of FIG. 5).

[0114] In downlink transmission, a physical channel (610) may include at least one of a physical broadcast channel (PBCH), a physical downlink shared channel (PDSCH), or a physical downlink control channel (PDCCH). The PDCCH may be used to carry downlink control information (DCI). Generally, downlink data refers to symbols transmitted through the PDSCH, and a downlink control signal may include symbols transmitted through the PDCCH. In addition, in the downlink, in addition to the channels illustrated in FIG. 6, a synchronization signal (e.g., a primary synchronization signal (PSS), a secondary synchronization signal (SSS)) and an SS / PBCH block including a broadcast signal (e.g., a PBCH)) may be transmitted for synchronization. In addition, in the downlink, a channel state information-reference signal (CSI-RS) for obtaining measurement or channel information, a demodulation reference signal (DMRS) for channel estimation and demodulation, and a phase tracking reference signal (PTRS) may be transmitted in the downlink.

[0115] In uplink transmission, the physical channel (610) may include at least one of a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), or a physical random access channel (PRACH). The PUSCH or PUCCH may be used to carry uplink control information (UCI). Generally, uplink data refers to symbols transmitted through the PUSCH, and the uplink control signal may include symbols corresponding to the UCI. For example, the UCI may include at least one of a scheduling request (SR), a hybrid automatic request (HARQ)-acknowledge (ACK) bit(s), or channel state information (CSI). In addition, in the uplink, in addition to the channels illustrated in FIG. 6, a DMRS and a PTRS for channel estimation and demodulation may be transmitted in the downlink for channel estimation.

[0116] The transmission channel (620) connects the physical layer and the medium access channel (MAC) layer located at an upper level of the physical layer, and can be classified according to how data is transmitted through the wireless interface. In the downlink, the transmission channel (620) may include at least one of a paging channel (PCH) for paging, a broadcast channel (BCH) for broadcasting system information, or a downlink shared channel (DL-SCH) for transmitting downlink data. In the uplink, the transmission channel (620) may include at least one of a random access channel (RACH) for transmitting a random access preamble or an uplink shared channel (UL-SCH) for transmitting downlink data.

[0117] The logical channel (630) is located above the transport channel and is mapped to the transport channel (620). The logical channel (630) can be divided into a control channel for transmitting control region information and a traffic channel for transmitting user region information. The control channel of the logical channel (630) can include at least one of a paging control channel (PCCH), a broadcast control channel (BCCH), a common control channel (CCCH), or a dedicated control channel (DCCH). The traffic channel of the logical channel (630) can include a dedicated traffic channel (DTCH).

[0118] In describing embodiments of the present disclosure, a random access signal may include sequences transmitted via a physical random access channel (PRACH). 'Data' may include signals other than a reference signal. For example, 'data' obtained by a receiver in uplink communication may include signals transmitted via a physical random access channel (PUSCH). However, the PUSCH is exemplary, and it is understood that embodiments of the present disclosure may also be applied to other channels requiring channel estimation (e.g., PDSCH, PBCH, PDCCH, PUCCH).

[0119] Figure 7 illustrates an example of the structure of a random access signal. The random access signal may be transmitted via a PRACH. The random access signal may also be referred to as a PRACH, a preamble, a RACH (random access channel) preamble, a RACH signal, a random access preamble, or terms having equivalent technical meanings.

[0120] Referring to FIG. 7, a random access signal (710) may include a CP (720) and a preamble body (730). The preamble body (730) may include one or more symbols (or one or more preamble symbols). The number of the one or more symbols may have various values ​​depending on the preamble format specified in the standard (e.g., 3GPP LTE, 3GPP NR). Reception of the random access signal (710) via the PRACH may be performed via the preamble body (730).

[0121] The random access signal (710) may be generated based on a sequence (e.g., a Zadoff-Chu (ZC) sequence) according to the preamble length. The preamble length is an LRA value and may have various values. For example, the length of the preamble may be 839. In another example, the length of the preamble may be 139.

[0122] Depending on the preamble length, a preamble format for a random access signal (710) may be determined. For example, a preamble format having a length of 839 may be configured as shown in Table 3.

[0123]

[0124]

[0125] For example, a preamble format with a length of 139 can be configured as shown in Table 4.

[0126]

[0127]

[0128] According to one embodiment, in a random access signal (710) of an OFDM-based system, an SCS that is equal to or smaller than the SCS used in an UL channel may be used to support wide cell coverage. For example, in an LTE system, the UL SCS may be set to 15 kHz, and the SCS of preamble format 0 may be set to 1.25 kHz.

[0129] For example, the random access signal (710) may be generated based on a ZC (zadoff-chu) sequence. The ZC sequence may be configured as shown in the following mathematical formula.

[0130]

[0131]

[0132] According to one embodiment, the terminal (120) can transmit a random access signal (e.g., random access signal (510), PRACH preamble) to the base station (110) through an uplink channel (e.g., PRACH). The base station (110) can receive the random access signal from the terminal (120). In an OFDM (Orthogonal Frequency Division Multiplexing) based mobile communication system (e.g., LTE, NR, NR-U (unlicensed)), a PRACH detector based on FFT / IFFT (Fast Fourier Transform / Inverse FFT) is generally required to receive the random access signal.

[0133] In the following specification, technical features of a PRACH detector for receiving a PRACH preamble will be described. For example, the PRACH detector can estimate (or identify) a frequency offset when receiving a PRACH preamble in an environment where a frequency offset exists. Meanwhile, in the present disclosure, the operation of a base station (110) including a PRACH detector is described to explain the operation for PRACH reception, but this description does not exclude that at least some of the operations of the base station (110) are performed by the DU (210) and at least some of the other operations are performed by the RU (220). That is, depending on the implementation method of the base station (110), all of the operations described below may be performed by a single network entity, or the operations may be divided and performed by multiple network entities (e.g., the DU (210), the RU (220)). In the following, for convenience of explanation, the operations described below will be described as being performed by the DU (210), but are not limited thereto.

[0134] According to one embodiment, a PRACH detector can receive a random access signal (or PRACH preamble) in an environment where a frequency offset exists. The PRACH detector can only receive the PRACH signal and may not estimate (or measure) the frequency offset. After the PRACH detector operates, a physical uplink shared channel (PUSCH) receiver has no information about the frequency offset, so it can estimate the frequency offset based on the maximum frequency offset. In an environment where a large frequency offset occurs (e.g., inside a high-speed train), a base station according to the NR standard can additionally arrange reference signals to reduce the interval of reference signals in the PUSCH. The base station according to the NR standard can include a PUSCH receiver capable of estimating and compensating for the frequency offset using narrowly spaced reference signals. The base station according to the NR standard can estimate a large frequency offset through the PUSCH receiver. However, in the PUSCH of the LTE standard, the interval of the reference signals can be fixed. For example, in the PUSCH of the LTE standard, the interval of the reference signal may be set to 0.5 ms. The base station of the LTE standard may include a frequency offset estimator that utilizes the CP within the PUSCH symbol to estimate a large frequency offset.

[0135] As described above, functional blocks for estimating a frequency offset may be required in a PUSCH receiver. However, if the frequency offset is estimated in advance through a PRACH detector, the functional blocks may be omitted. In the following specification, technical features for estimating a frequency offset in advance through a PRACH detector and compensating for the frequency offset estimated through the PRACH detector in a PUSCH receiver will be described. Accordingly, an example of a PRACH detector for estimating a frequency offset through a PRACH detector will be described below.

[0136] Fig. 8 illustrates an example of a PRACH detector. The operations of the PRACH detector described in Fig. 8 may be performed by a base station (e.g., base station 110). To explain the operations of the PRACH detector, functional blocks are illustrated, but the functional blocks are exemplary and are not to be construed as limiting other embodiments of the present disclosure. In addition, at least some of the operations of the PRACH detector may be performed by a network entity (e.g., RU 220), and the remaining operations may be performed by another network entity (e.g., DU 210). Terms such as “... unit” and “... device” used hereinafter mean a unit that processes at least one function or operation, and this may be implemented by hardware, software, or a combination of hardware and software.

[0137]

[0138] In operation (801), the base station (110) may perform CP removal. CP removal may be performed in the time domain. The base station (110) may remove the CP (e.g., CP (720) of FIG. 7) from the received signal, and then generate a symbol-unit signal (hereinafter, a time domain signal) based on the preamble body (e.g., preamble body (730) of FIG. 7). According to one embodiment, operation (801) may be performed by the RU (220) of the base station (110) through specific functional separation. In other words, the CP removal function corresponding to operation (801) may be performed by the RU (220). According to another embodiment, operation (801) may be performed by the DU (220) of the base station (110) through specific functional separation. For example, the time domain signal may be expressed by the following mathematical equation. According to one embodiment, the operation (801) for the random access signal may be performed by the DU (220), and the operation (801) for the data signal may be performed by the RU (210).

[0139]

[0140]

[0141] In operation (802), the base station (110) may perform an FFT operation. The base station (110) may generate a frequency domain signal by performing an FFT operation on the time domain signal. In one embodiment, due to functional separation, operation (802) may be performed by the RU (220) of the base station (110). In other words, the FFT operation corresponding to operation (802) may be performed by the RU (220). In another embodiment, due to specific functional separation, operation (802) may be performed by the DU (210) of the base station (110). In one embodiment, operation (802) for a random access signal may be performed by the DU (220).

[0142] For example, the frequency domain signal can be expressed by the following mathematical formula.

[0143]

[0144]

[0145] In operation (803), the base station (110) may perform subcarrier demapping. Subcarrier demapping may identify a signal (hereinafter, a preamble signal) corresponding to subcarriers allocated for a preamble in a frequency domain signal. The base station (110) may identify the preamble signal in the frequency domain signal. According to one embodiment, by specific functional separation, operation (803) may be performed by the DU (210) of the base station (110). In other words, the subcarrier demapping function corresponding to operation (803) may be performed by the DU (210). According to another embodiment, by specific functional separation, operation (803) may be performed by the RU (220) of the base station (110). According to one embodiment, operation (803) for a random access signal may be performed by the DU (220).

[0146] For example, the above preamble signal can be expressed by the following mathematical formula.

[0147]

[0148]

[0149]

[0150] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (804) may be performed by the DU (210) of the base station (110). However, in another embodiment, by another type of functional separation, operation (804) may also be performed by the RU (220) of the base station (110). In one embodiment, operation (804) for a random access signal may be performed by the DU (220).

[0151]

[0152] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (805) may be performed by DU (210) of base station (110). However, in another embodiment, by another type of functional separation, operation (805) may also be performed by RU (220) of base station (110). In one embodiment, operation (805) for random access signal may be performed by DU (220).

[0153]

[0154]

[0155] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (806) may be performed by the DU (210) of the base station (110). However, in another embodiment, by another type of functional separation, operation (806) may also be performed by the RU (220) of the base station (110). In one embodiment, operation (806) for a random access signal may be performed by the DU (220).

[0156]

[0157] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (807) may be performed by DU (210) of base station (110). However, in another embodiment, by another type of functional separation, operation (807) may also be performed by RU (220) of base station (110). In one embodiment, operation (807) for random access signal may be performed by DU (220).

[0158]

[0159] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (808) may be performed by the DU (210) of the base station (110). However, in another embodiment, by another type of functional separation, operation (808) may also be performed by the RU (220) of the base station (110). In one embodiment, operation (808) for a random access signal may be performed by the DU (220).

[0160]

[0161] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (809) may be performed by DU (210) of base station (110). However, in another embodiment, by another type of functional separation, operation (809) may also be performed by RU (220) of base station (110). In one embodiment, operation (809) for random access signal may be performed by DU (220).

[0162]

[0163] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (810) may be performed by DU (210) of base station (110). However, in another embodiment, by another type of functional separation, operation (810) may also be performed by RU (220) of base station (110). In one embodiment, operation (810) for random access signal may be performed by DU (220).

[0164]

[0165]

[0166]

[0167]

[0168] In one embodiment, by a specific type of functional separation (e.g., option 7-2, 7-2x), operation (811) may be performed by DU (210) of base station (110). However, in another embodiment, by another type of functional separation, operation (811) may also be performed by RU (220) of base station (110). In one embodiment, operation (811) for random access signal may be performed by DU (220).

[0169] According to one embodiment, operations (805) to (811) may be performed repeatedly as many times as the number of preamble sequences (Q).

[0170]

[0171] The base station (110) may include a detection unit (813). For example, the DU (210) of the base station (110) may include the detection unit (813). The detection unit (813) may compare the power and a threshold value for each ZCZ within the preamble sequence. The detection unit (813) may determine whether a random access signal is detected by comparing the power and the threshold value. For example, if the power is greater than the threshold value, the detection unit (813) may determine that a random access signal is detected. If the power is not greater than the threshold value, the detection unit (813) may determine that a random access signal is not detected. Although not shown in FIG. 8, the base station (110) may transmit a random access response to a terminal (e.g., terminal (120)) based on the detected random access signal. In addition, the base station (110) may determine a time offset (e.g., timing advance (TA)) based on the detected random access signal.

[0172] According to one embodiment, operations (805) to (811) may be performed repeatedly as many times as the number of preamble sequences (Q). According to one embodiment, the profiler (812) and the detection unit (813) may determine whether a random access signal is detected by repeating the same number of preamble sequences (Q).

[0173]

[0174] Figure 9 shows an example of a frequency offset estimation unit of a PRACH detector.

[0175] Figure 10 shows examples of graphs for estimating frequency offset.

[0176] Referring to Fig. 9, the obtained according to the operation (806) of Fig. 8 can be composed as shown in the following mathematical formula.

[0177]

[0178]

[0179]

[0180]

[0181] In mathematical equation 9 can contain all items except signals. The average value can be constructed as shown in the following mathematical formula.

[0182]

[0183]

[0184]

[0185]

[0186]

[0187]

[0188] Obtained according to actions (809) and (810) can be composed as shown in the following mathematical formula.

[0189]

[0190] Regarding equation 14, can be constructed (approximated, estimated) as in the following mathematical formula.

[0191]

[0192] Referring to Equations 14 and 15, The average value can be constructed as shown in the following mathematical formula.

[0193]

[0194]

[0195]

[0196] Referring to mathematical equation 17, can be approximated by the following mathematical formula.

[0197]

[0198]

[0199]

[0200]

[0201]

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228] Figure 11 illustrates a flowchart regarding the operation of an electronic device.

[0229] Referring to FIG. 11, an electronic device (or a processor of the electronic device) may be included in a base station (110). For example, the electronic device may be configured to receive a signal (e.g., a preamble signal or a data signal) transmitted from a terminal. According to an embodiment, the base station (110) may be divided into a DU (210) and a RU (220). The DU (210) may perform at least a part of operations (1110) to (1150). The RU (220) may perform the remaining part of operations (1110) to (1150). For example, the RU (220) may obtain a preamble signal (or a random access signal) using multiple antennas. The RU (220) may transmit the preamble signal to the DU (210). DU (210) can perform the following operations (1110) to (1150) based on obtaining a preamble signal from RU (220).

[0230] In operation (1110), the electronic device may obtain a preamble signal based on the PRACH region. For example, the electronic device may obtain a preamble signal related to signals received via multiple antennas based on the PRACH region. For example, the preamble signal may include the random access signal (710) of FIG. 7.

[0231] For example, a preamble signal may include a cyclic prefix and multiple preamble symbols. The multiple preamble symbols may be configured based on a Zadoff-Chu (ZC) sequence.

[0232] In operation (1120), the electronic device can obtain delay information for the preamble signal. For example, an example of the delay information is as described above. The acquired delay information may include delay values ​​generated by cyclic shift and air delay.

[0233] In operation (1130), the electronic device may obtain energy information of the preamble signal obtained through a correlation operation. For example, the electronic device may perform a correlation operation on the preamble signal. The operation of performing the correlation operation on the preamble signal may be related to operation (805) of FIG. 8. For example, the electronic device may obtain energy information of the preamble signal obtained through a correlation operation. The energy information of the preamble signal may be obtained according to operation (810) of FIG. 8 (or Equation 14).

[0234] In operation (1140), the electronic device may estimate a frequency offset for the preamble signal. For example, the electronic device may estimate a frequency offset for the preamble signal based on delay information and energy information.

[0235]

[0236] For example, multiple frequency indices may be determined based on the type of the preamble signal. The type of the preamble signal may be one of 'unrestricted', 'restricted type A' (or 'type A'), and 'restricted type B' (or 'type B'). Depending on the type of the preamble signal, multiple frequency indices may be determined.

[0237] According to one embodiment, the electronic device can determine a frequency index having a maximum energy value among frequency indices. An example of a frequency index having a maximum energy value is the above-described w max The electronic device can determine the above-determined frequency index as a reference frequency index.

[0238] The electronic device can identify a first frequency index and a second frequency index with respect to a reference frequency index. The first frequency index may have a designated index value (e.g., '1') that is smaller than the reference frequency index. The second frequency index may have a designated index value that is larger than the reference frequency index. The electronic device can determine another reference frequency index based on a comparison of the energy values ​​of the first frequency index and the second frequency index.

[0239]

[0240]

[0241] According to one embodiment, the electronic device can determine two frequency indices having the largest energy values ​​among the frequency indices. The smaller of the two frequency indices is used as a reference frequency (or N f ) can be determined. The larger value of the two frequency indices is used as the reference frequency (or N f +1) can be determined.

[0242] According to one embodiment, an electronic device may estimate a frequency offset of a preamble signal based on a ratio of an energy value of a reference frequency index and an energy value of another reference frequency index. The electronic device may estimate the frequency offset using the ratio, the reference frequency index, and the subcarrier spacing of the preamble signal. The electronic device may estimate the frequency offset using the above-described mathematical expression 28.

[0243] In operation (1150), the electronic device may compensate for an estimated frequency offset for a data signal received based on a PUSCH region. The electronic device may estimate a frequency offset using a preamble signal acquired based on the PRACH region and apply the estimated frequency offset to the data signal received based on the PUSCH region. For example, the electronic device may compensate for a rough frequency offset for the data signal using the preamble signal. The electronic device may estimate an accurate frequency offset based on the data signal (or a reference signal of the data signal). By compensating the accurate frequency offset for the data signal, the electronic device may acquire data. Since the electronic device compensates for a rough frequency offset for the data signal in advance, the implementation complexity for receiving the data signal may be reduced.

[0244] According to one embodiment, an electronic device may include a transceiver, at least one processor including processing circuitry, and one or more storage media, and a memory storing instructions. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain a preamble signal associated with signals received through a plurality of antennas based on a physical random access channel (PRACH) region. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain delay information for the preamble signal. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to obtain energy information of the preamble signal obtained through a correlation operation. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to estimate a frequency offset for the preamble signal based on the delay information and the energy information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to compensate for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0245] In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to determine a reference frequency range based on the delay information and the energy information. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to estimate the frequency offset based on an energy value for each of a plurality of frequency indices within the reference frequency range.

[0246] According to one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to determine a frequency index having a maximum energy value among the plurality of frequency indices. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to determine the determined frequency index as a reference frequency index.

[0247] According to one embodiment, the plurality of frequency indices may be determined based on the type of the preamble signal.

[0248] In one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to identify a first frequency index and a second frequency index relative to the reference frequency index. The instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to determine another reference frequency index based on a comparison of an energy value of the first frequency index and an energy value of the second frequency index.

[0249] According to one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to estimate the frequency offset based on a ratio of an energy value of the reference frequency index and an energy value of the other reference frequency index.

[0250] According to one embodiment, the instructions, when individually or collectively executed by the at least one processor, may cause the electronic device to estimate the frequency offset using the ratio, the reference frequency index, and the subcarrier spacing of the preamble signal.

[0251] According to one embodiment, the preamble signal and the data signal can be transmitted from a terminal.

[0252] According to one embodiment, the preamble signal may include a cyclic prefix and a plurality of preamble symbols.

[0253] According to one embodiment, the plurality of preamble symbols may be configured based on a ZC (zadoff chu) sequence.

[0254] According to one embodiment, a method performed by an electronic device may include an operation of obtaining a preamble signal related to signals received through a plurality of antennas based on a physical random access channel (PRACH) region. The method may include an operation of obtaining delay information for the preamble signal. The method may include an operation of obtaining energy information of the preamble signal obtained through a correlation operation. The method may include an operation of estimating a frequency offset for the preamble signal based on the delay information and the energy information. The method may include an operation of compensating for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0255] According to one embodiment, the method may include an operation of determining a reference frequency range based on the delay information and the energy information. The method may include an operation of estimating the frequency offset based on an energy value for each of a plurality of frequency indices within the reference frequency range.

[0256] According to one embodiment, the method may include an operation of determining a frequency index having a maximum energy value among the plurality of frequency indices. The method may include an operation of determining the determined frequency index as a reference frequency index.

[0257] According to one embodiment, the plurality of frequency indices may be determined based on the type of the preamble signal.

[0258] In one embodiment, the method may include an operation of identifying a first frequency index and a second frequency index with respect to the reference frequency index. The method may include an operation of determining another reference frequency based on a comparison of an energy value of the first frequency index and an energy value of the second frequency index.

[0259] According to one embodiment, the method may include estimating the frequency offset based on a ratio of an energy value of the reference frequency index and an energy value of the other reference frequency index.

[0260] According to one embodiment, the method may include an operation of estimating the frequency offset using the ratio, the reference frequency index, and the subcarrier spacing of the preamble signal.

[0261] According to one embodiment, the preamble signal and the data signal can be transmitted from a terminal.

[0262] According to one embodiment, the preamble signal may include a cyclic prefix and a plurality of preamble symbols.

[0263] According to one embodiment, a non-transitory computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed by a processor of an electronic device, cause the electronic device to obtain a preamble signal associated with signals received via a plurality of antennas based on a physical random access channel (PRACH) region. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to obtain delay information for the preamble signal. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to obtain energy information of the preamble signal obtained through a correlation operation. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to estimate a frequency offset for the preamble signal based on the delay information and the energy information. The one or more programs may include instructions that, when executed by the processor, cause the electronic device to compensate for the estimated frequency offset for a data signal received based on a physical uplink shared channel (PUSCH) region.

[0264] According to the above-described embodiment, when a preamble signal configured based on a ZC sequence is received, a frequency offset can be estimated (or measured). When an electronic device receives a ZC sequence, the electronic device can estimate the frequency offset based on the characteristics of the ZC sequence according to the frequency offset. The electronic device can estimate and compensate for a frequency offset with an error of several hundred Hz or less through the preamble signal. The electronic device can pre-compensate a data signal regarding a PUSCH according to the estimated frequency offset and compensate for the accurate frequency offset. Therefore, the reception complexity of the PUSCH can be reduced and performance can be improved.

[0265] 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.

[0266] 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 within 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 specification of the present disclosure.

[0267] 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.

[0268] 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.

[0269] 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.

[0270] 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 electronic devices, Transmitter and receiver; At least one processor comprising processing circuitry; and comprising one or more storage media, and including a memory storing instructions; The above instructions, when individually or collectively executed by the at least one processor, Based on the PRACH (physical random access channel) region, a preamble signal related to signals received through multiple antennas is obtained, Obtaining delay information for the above preamble signal, Obtaining energy information of the preamble signal obtained through a correlation operation, Based on the above delay information and the above energy information, a frequency offset for the preamble signal is estimated, Causing the electronic device to compensate for the estimated frequency offset for a data signal received based on a PUSCH (physical uplink shared channel) region. Electronic devices.

2. In the first paragraph, when the instructions are individually or collectively executed by the at least one processor, Based on the above delay information and the above energy information, a reference frequency range is determined, Further causing the electronic device to estimate the frequency offset based on an energy value for each of a plurality of frequency indices within the reference frequency range. Electronic devices.

3. In the second paragraph, when the instructions are individually or collectively executed by the at least one processor, Among the above multiple frequency indices, the frequency index having the maximum energy value is determined, Further causing the electronic device to determine the above-determined frequency index as a reference frequency index, Electronic devices.

4. In the third paragraph, the plurality of frequency indices are, Determined based on the type of the above preamble signal, Electronic devices.

5. In the third paragraph, when the instructions are individually or collectively executed by the at least one processor, Identifying a first frequency index and a second frequency index with respect to the above reference frequency index, Further causing the electronic device to determine another reference frequency index based on a comparison of the energy value of the first frequency index and the energy value of the second frequency index. Electronic devices.

6. In the fifth paragraph, when the instructions are individually or collectively executed by the at least one processor, Further causing the electronic device to estimate the frequency offset based on a ratio of the energy value of the reference frequency index and the energy value of the other reference frequency index. Electronic devices.

7. In the sixth paragraph, when the instructions are individually or collectively executed by the at least one processor, Further causing the electronic device to estimate the frequency offset using the above ratio, the reference frequency index and the subcarrier spacing of the preamble signal. Electronic devices.

8. In the first paragraph, the preamble signal and the data signal, Transmitted from the terminal, Electronic devices.

9. In the first paragraph, the preamble signal, Containing a cyclic prefix and multiple preamble symbols, Electronic devices.

10. In the 9th paragraph, the plurality of preamble symbols are: It is constructed based on the ZC (zadoff chu) sequence. Electronic devices.

11. In a method performed by an electronic device, An operation of obtaining a preamble signal related to signals received through multiple antennas based on a PRACH (physical random access channel) region; An operation of obtaining delay information for the above preamble signal; An operation of obtaining energy information of the preamble signal obtained through a correlation operation; An operation of estimating a frequency offset for the preamble signal based on the delay information and the energy information; and An operation for compensating for the estimated frequency offset for a data signal received based on a PUSCH (physical uplink shared channel) region, method.

12. In the 11th paragraph, the method, An operation of determining a reference frequency range based on the above delay information and the above energy information; and Further comprising an operation of estimating the frequency offset based on an energy value for each of a plurality of frequency indices within the reference frequency range. method.

13. In the 12th paragraph, the method, An operation of determining a frequency index having a maximum energy value among the plurality of frequency indices; and Further comprising an operation of determining the above-determined frequency index as a reference frequency index. method.

14. In the 13th paragraph, the plurality of frequency indices are, Determined based on the type of the above preamble signal, method.

15. In a non-transitory computer-readable storage medium storing one or more programs, said one or more programs, when executed by a processor of an electronic device, Based on the PRACH (physical random access channel) region, a preamble signal related to signals received through multiple antennas is obtained, Obtaining delay information for the above preamble signal, Obtaining energy information of the preamble signal obtained through a correlation operation, Based on the above delay information and the above energy information, a frequency offset for the preamble signal is estimated, Including instructions causing the electronic device to compensate for the estimated frequency offset for a data signal received based on a PUSCH (physical uplink shared channel) region. A non-transitory computer-readable storage medium.

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