APPARATUS AND METHOD FOR FRONTHAUL TRANSMISSION IN A WIRELESS COMMUNICATION SYSTEM - Patent application

Abstract

The present disclosure relates to a 5G (5th generation) or pre-5G communication system for supporting higher data rates after 4G (4th Generation) communication systems such as LTE (Long Term Evolution). According to various embodiments of the present disclosure, a radio unit (RU) device of a base station in a wireless communication system includes at least one transceiver and at least one processor coupled to the at least one transceiver, and the at least one processor is configured to receive a first control message including a section extension field from a digital unit (DU) via a fronthaul interface, identify additional information based on the section extension field, and obtain beamforming weights based on the additional information, and the first control message may be configured to schedule a terminal in a control plane.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to wireless communication systems, and more particularly to an apparatus and method for fronthaul transmission in a wireless communication system. [Background technology]

[0002] 4G(4 th Since the commercialization of the 5G (5G) communication system, improved 5G (5G) has been developed to meet the increasing demand for wireless data traffic. th Efforts are being made to develop 5G (Next Generation) or pre-5G communication systems. For this reason, 5G or pre-5G communication systems are referred to as Beyond 4G Network communication systems or Post-LTE (Long Term Evolution) systems.

[0003] To achieve high data transmission rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., 60 GHz band, etc.). To mitigate the path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large scale antenna technologies are being discussed for 5G communication systems.

[0004] In addition, to improve the system network, technologies being developed for the 5G communication system include advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and receive interference cancellation.

[0005] In addition, the 5G system includes advanced coding modulation (ACM) methods such as FQAM (Hybrid Frequency Shift Keying and Quadrature Amplitude Modulation) and SWSC (Sliding Window Superposition Coding), as well as advanced access technologies such as FBMC (Filter Bank Multi Carrier), NOMA (Non Orthogonal Multiple Access), and SCMA (Sparse Code Multiple Access).

[0006] As the transmission capacity of wireless communication systems increases, function split is being applied to separate base stations functionally. In this function split, a base station can be separated into a digital unit (DU) and a radio unit (RU), a fronthaul is defined for communication between the DU and RU, and transmission through the fronthaul is required. Summary of the Invention [Problem to be solved by the invention]

[0007] Based on the above discussion, the present disclosure provides an apparatus and method for transmitting control messages over a fronthaul interface.

[0008] The present disclosure also provides an apparatus and method for transmitting management messages over a fronthaul interface in a wireless communication system.

[0009] The present disclosure also provides an apparatus and method for communicating both scheduling information and other information over a fronthaul interface in a wireless communication system.

[0010] The present disclosure also provides an apparatus and method for communicating together scheduling information and, in particular, regularization parameters, over a fronthaul interface in a wireless communication system.

[0011] The present disclosure also provides an apparatus and method for reducing the memory burden of a digital unit (DU) and a radio unit (RU) due to the storage of regularization parameters when the RU is operated in a wireless communication system.

[0012] The present disclosure also provides a functional structure of an RU for processing regularization parameters in a wireless communication system. [Means for solving the problem]

[0013] According to various embodiments of the present disclosure, a method for operating a DU (digital unit) of a base station in a wireless communication system includes a step of setting a section extension field including additional information, and a step of transmitting a first control message including the section extension field to a RU (radio unit) via a fronthaul interface, and the first control message may be configured to schedule a terminal in a control plane.

[0014] According to various embodiments of the present disclosure, a method for operating a radio unit (RU) of a base station in a wireless communication system includes receiving a first control message including a section extension field from a digital unit (DU) via a fronthaul interface, identifying additional information based on the section extension field, and obtaining beamforming weights based on the additional information, wherein the first control message may be configured to schedule a terminal in a control plane.

[0015] According to various embodiments of the present disclosure, a DU (digital unit) device of a base station in a wireless communication system includes at least one transceiver and at least one processor coupled to the at least one transceiver, wherein the at least one processor is configured to set a section extension field including additional information and transmit a first control message including the section extension field to a RU (radio unit) via a fronthaul interface, and the first control message may be configured to schedule a terminal in a control plane.

[0016] According to various embodiments of the present disclosure, an apparatus of a radio unit (RU) of a base station in a wireless communication system includes at least one transceiver and at least one processor coupled to the at least one transceiver, wherein the at least one processor is configured to receive a first control message including a section extension field from a digital unit (DU) via a fronthaul interface, identify additional information based on the section extension field, and obtain beamforming weights based on the additional information, and the first control message may be configured to schedule a terminal in a control plane. Effect of the Invention

[0017] Apparatus and methods according to various embodiments of the present disclosure enable efficient operation of an interface between a digital unit (DU) and a radio unit (RU) through control messages and management messages.

[0018] The effects obtained by the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present disclosure pertains from the following description. [Brief description of the drawings]

[0019] [Figure 1A] FIG. 1 illustrates a wireless communication system in accordance with various embodiments of the present disclosure. [Figure 1B] A diagram showing an example of a fronthaul structure with functional separation of a base station according to various embodiments of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating the configuration of a digital unit (DU) according to various embodiments of the present disclosure. [Diagram 3] A diagram showing the configuration of a radio unit (RU) according to various embodiments of the present disclosure. [Figure 4] FIG. 2 illustrates an example of function split according to various embodiments of the present disclosure. [Figure 5A] FIG. 13 is a diagram showing an example of a control message according to Section type 6. [Figure 5B] A diagram showing an example of the functional configuration of an RU for beamforming information processing. [Figure 5C] FIG. 1 is a diagram illustrating the relationship between a regularization factor and scheduling. [Figure 6] FIG. 2 illustrates an example of an extension field according to various embodiments of the present disclosure. [Figure 7] A figure showing an example of a management message for Section type 6 according to various embodiments of the present disclosure. [Figure 8A]A diagram showing the operation flow of a DU for an extension field according to various embodiments of the present disclosure. [Figure 8B] FIG. 1 illustrates a flow of RU operations for an extension field according to various embodiments of the present disclosure. [Figure 9A] A diagram showing the operational flow of a DU for a management message for Section type 6 according to various embodiments of the present disclosure. [Figure 9B] A diagram showing the operational flow of an RU for management messages for Section type 6 according to various embodiments of the present disclosure. [Figure 10] A diagram showing an example of a functional configuration of a RU for beamforming information processing according to various embodiments of the present disclosure. [Figure 11] FIG. 2 illustrates a relationship between regularization factor and scheduling according to various embodiments of the present disclosure. [Figure 12] A diagram showing an example of a relationship between a DU and a RU according to a section extension field according to various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The terms used in this disclosure are merely used to describe certain embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates a different meaning. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by a person having ordinary skill in the technical field described in this disclosure. Terms used in this disclosure that are defined in a general dictionary may be interpreted as meanings that are the same as or similar to the meanings in the context of the relevant art, and are not interpreted as ideal or overly formal meanings unless clearly defined in this disclosure. In some cases, even terms defined in this disclosure cannot be interpreted to exclude embodiments of the present disclosure.

[0021] In the various embodiments of the present disclosure described below, a hardware approach is described as an example, but since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0022] In the following explanation, the following terms are used: terms referring to signals (e.g., message, information, preamble, signal, signaling, sequence, stream), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms indicating operation states (e.g., step, operation, procedure), terms referring to data (e.g., user stream, IQ data, information, bit, symbol, codeword), terms referring to channels, terms referring to control information (e.g., downlink control information (DCI), medium access control element (CE), radio resource control (RRC) signaling), network entity (NE), The terms referring to a device entity, the terms referring to components of a device, etc. are exemplified for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[0023] In addition, in this disclosure, the expressions "more than" or "less than" may be used to determine whether a particular condition is satisfied or fulfilled, but this is merely a description to express one example and does not exclude the description "more than" or "less than." A condition described as "more than" may be replaced with "more than," a condition described as "less than," and a condition described as "more than and less than" may be replaced with "more than and less than."

[0024] In addition, the present disclosure describes various embodiments using terms used in some communication standards (e.g., 3GPP (registered trademark, 3rd Generation Partnership Project), xRAN (extensible radio access network), O-RAN (open-radio access network)), but this is merely an example for the purpose of explanation. Various embodiments of the present disclosure may be easily modified and applied to other communication systems.

[0025] FIG 1A illustrates a wireless communication system according to various embodiments of the present disclosure. FIG 1 illustrates a base station 110, a terminal 120, and a terminal 130 as some of the nodes that use wireless channels in the wireless communication system. Although FIG 1 illustrates only one base station, other base stations identical or similar to the base station 110 may also be included.

[0026] The base station 110 is a network infrastructure that provides wireless connectivity to the terminals 120 and 130. The base station 110 has coverage defined in a given geographical area based on the distance over which a signal can be transmitted. The base station 110 may be called an "access point (AP)", "eNodeB (eNB)", "5th generation node", "next generation nodeB (gNB)", "wireless point", "transmission / reception point (TRP)", or other terms having an equivalent technical meaning, in addition to a base station.

[0027] Each of the terminals 120 and 130 is a device used by a user and communicates with the base station 110 via a wireless channel. A link from the base station 110 to the terminal 120 or the terminal 130 is called a downlink (DL), and a link from the terminal 120 or the terminal 130 to the base station 110 is called an uplink (UL). The terminals 120 and 130 can communicate with each other via a wireless channel. At this time, a link between the terminals 120 and 130 (device-to-device link; D2D) is called a sidelink, and the sidelink can be used interchangeably with a PC5 interface. In some cases, at least one of the terminals 120 and 130 can be operated without the involvement of a user. That is, at least one of the terminals 120 and 130 is a device that performs machine type communication (MTC) and may not be carried by a user. Each of terminal 120 and terminal 130 may be referred to as a terminal, as well as a “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.

[0028] Base station 110, terminal 120, and terminal 130 can perform beamforming. The base station 110, the terminal 120, and the terminal 130 may transmit and receive radio signals in a relatively low frequency band (e.g., FR1 (frequency range 1) of NR) as well as in a high frequency band (e.g., FR2 of NR, mmWave band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz)). In some embodiments, the base station may communicate with the terminal within a frequency range corresponding to FR1. In some embodiments, the base station may communicate with the terminal within a frequency range corresponding to FR2. In this case, the base station 110, the terminal 120, and the terminal 130 may perform beamforming to improve channel gain. Here, beamforming may include transmit beamforming and receive beamforming. That is, the base station 110, the terminal 120, and the terminal 130 may provide directivity to a transmit signal or a receive signal. To this end, the base station 110 and the terminals 120 and 130 may perform beam search or beam management. A serving beam 112, 113, 121, or 131 can be selected by a quasi co-located (QCL) procedure. After the serving beam 112, 113, 121, or 131 is selected, subsequent communication can be performed by resources that are in a quasi co-located (QCL) relationship with the resources that transmitted the serving beam 112, 113, 121, or 131.

[0029] A first antenna port and a second antenna port may be said to be in a QCL relationship if the large-scale characteristics of the channel carrying symbols on the first antenna port can be inferred from the channel carrying symbols on the second antenna port. For example, the large-scale characteristics may include at least one of a delay spread, a Doppler spread, a Doppler shift, an average gain, an average delay, and a spatial receiver parameter.

[0030] Although both the base station and the terminal are illustrated as performing beamforming in FIG. 1A, various embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Also, the base station may or may not perform beamforming. That is, only one of the base station and the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0031] In the present disclosure, a beam indicates a spatial flow of a signal in a wireless channel and is formed by one or more antennas (or antenna elements), and such a forming process can be referred to as beamforming. Beamforming can include analog beamforming and digital beamforming (e.g., precoding). Reference signals transmitted based on beamforming can include, for example, a demodulation-reference signal (DM-RS), a channel state information-reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), and a sounding reference signal (SRS). In addition, IEs such as a CSI-RS resource or an SRS-resource can be used as a configuration for each reference signal, and such a configuration can include information associated with the beam. The information associated with the beam may indicate whether the configuration (e.g., a CSI-RS resource) uses the same spatial domain filter as other configurations (e.g., other CSI-RS resources in the same CSI-RS resource set) or a different spatial domain filter, or which reference signal it is quasi-co-located with, and if so, what type (e.g., QCL type A, B, C, D).

[0032] Although both the base station and the terminal are illustrated as performing beamforming in FIG. 1A, various embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Also, the base station may or may not perform beamforming. That is, 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 past, in communication systems where the cell radius of base stations was relatively large, each base station was installed to include the functions of a digital processing unit (or DU (digital unit)) and an RF (radio frequency) processing unit (or RU (radio unit)). th In the 1990s (1991-1992) and / or later communication systems, high frequency bands have been used, and as the cell radius of base stations has become smaller, the number of base stations to cover a specific area has increased, and the burden of installation costs on operators to install the increased number of base stations has 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 distributed geographically to cover a specific area. Hereinafter, a base station arrangement structure and an extension example according to various embodiments of the present disclosure will be described with reference to FIG. 1B.

[0034] 1B shows an example of a fronthaul structure based on functional separation of a base station according to various embodiments of the present disclosure. The fronthaul is different from the backhaul between the base station and the core network, and refers to an entity between the wireless LAN and the base station.

[0035] Referring to FIG. 1B, the base station 110 may include a DU 160 and an RU 180. A fronthaul 170 between the DU 160 and the RU 180 may include ax For operation of the fronthaul 170, an interface such as enhanced common public radio interface (eCPRI) or radio over ethernet (ROE) may be used.

[0036] As communication technology develops, mobile data traffic increases, which in turn significantly increases the bandwidth requirements for the fronthaul between digital and wireless units. In a deployment 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 may be implemented to perform more functions for the PHY layer in addition to radio frequency (RF) functions.

[0037] The DU 160 may be responsible for higher layer functions of a wireless network. For example, the DU 160 may perform a MAC layer function and a part of a PHY layer. Here, the part of the PHY layer refers to a function of the PHY layer that is performed at a higher stage, 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 the DU 160 complies with the O-RAN standard, it may be referred to as an O-DU (O-RAN DU). The DU 160 may be expressed as a first network entity for a base station (e.g., gNB) in the embodiments of the present disclosure, as necessary.

[0038] The RU 180 may be responsible for lower layer functions of a wireless network. For example, the RU 180 may perform a part of the PHY layer and an RF function. Here, the part of the PHY layer refers to a function of the PHY layer that is performed at a relatively lower stage than the DU 160, and may include, for example, IFFT transformation (or FFT transformation), CP insertion (CP removal), and digital beamforming. A specific example of such functional separation is described in detail in FIG. 4. The RU 180 may be referred to as an "access unit (AU)", "access point (AP)", "transmission / reception point (TRP)", "remote radio head (RRH)", "radio unit (RU)", or other terms having equivalent technical meanings. According to an embodiment, if the RU 180 complies with the O-RAN standard, it may be referred to as an O-RU (O-RAN RU). The RU 180 may be expressed as a second network entity for a base station (e.g., gNB) in the embodiments of the present disclosure, as necessary.

[0039] Although FIG. 1B illustrates the base station including a DU and an RU, various embodiments of the present disclosure are not limited thereto. In some embodiments, the base station may be implemented in a distributed deployment with a centralized unit (CU) configured to perform functions of upper layers (e.g., packet data convergence protocol (PDCP), RRC) of an access network and a distributed unit (DU) configured to perform functions of lower layers. In this case, the distributed unit (DU) may include a digital unit (DU) and a radio unit (RU) in FIG. 1. Between a core (e.g., 5G core (5GC) or next generation core (NGC)) network and a radio network (RAN), the base station may be implemented in a structure in which a CU, a DU, and a RU are arranged in this order. The interface between the CU and the distributed unit (DU) may be referred to as an F1 interface.

[0040] A centralized unit (CU) is connected to one or more DUs and can handle functions of a higher layer than the DU. For example, the CU can handle functions of the radio resource control (RRC) and packet data convergence protocol (PDCP) layers, and the DU and RU can handle functions of lower layers. The DU can perform radio link control (RLC), media access control (MAC), and some functions of the physical layer (high PHY), and the RU can handle the remaining functions of the PHY layer (low PHY). In addition, as an example, a digital unit (DU) can be included in a distributed unit (DU) depending on the implementation of a distributed arrangement of a base station. Hereinafter, unless otherwise defined, the operation of a digital unit (DU) and an RU will be described, but various embodiments of the present disclosure can be applied to either a base station arrangement including a CU or an arrangement in which a DU is directly connected to a core network without a CU (i.e., a CU and a DU are integrated and implemented as one entity).

[0041] 2 shows a configuration of a DU in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in FIG. 2 can be understood as a part of a base station and as a configuration of the DU 160 in FIG. 1B. The terms "module", "device", etc. used below refer to a unit that processes at least one function or operation, which can be implemented in hardware or software, or a combination of hardware and software.

[0042] Referring to FIG. 2, the DU 160 includes a communication unit 210, a storage unit 220, and a control unit 230.

[0043] The communication unit 210 can perform functions for transmitting and receiving signals in a wired communication environment. The communication unit 210 can include a wired interface for controlling a direct connection between devices via a transmission medium (e.g., copper wire, optical fiber). For example, the communication unit 210 can transmit an electrical signal to another device via a copper wire, or convert between an electrical signal and an optical signal. The communication unit 210 can be connected to a radio unit (RU). The communication unit 210 can be connected to a core network or a CU in a distributed configuration.

[0044] The communication unit 210 may also perform a function for transmitting and receiving signals in a wireless communication environment. For example, the communication unit 210 may perform a conversion function between a baseband signal and a bit string according to a physical layer standard of a system. For example, when transmitting data, the communication unit 210 generates complex symbols by encoding and modulating a transmission bit string. Also, when receiving data, the communication unit 210 recovers a received bit string by demodulating and decoding a baseband signal. Also, the communication unit 210 may include multiple transmission and reception paths. Also, according to an embodiment, the communication unit 210 may be connected to a core network or to another node (e.g., an integrated access backhaul (IAB)).

[0045] The communication unit 210 can transmit and receive signals. To this end, the communication unit 210 can include at least one transceiver. For example, the communication unit 210 can transmit a synchronization signal, a reference signal, system information, a message, a control message, a stream, control information, or data. In addition, the communication unit 210 can perform beamforming.

[0046] The communication unit 210 transmits and receives signals as described above. Therefore, all or part of the communication unit 210 can be referred to as a "transmitter," a "receiver," or a "transmitter / receiver." In the following description, transmission and reception via a wireless channel are used to include the above-mentioned processing performed by the communication unit 210.

[0047] Although not shown in FIG 2, the communication unit 210 may further include a backhaul communication unit for connection to a core network or other base stations. The backhaul communication unit provides an interface for communication with other nodes in the network. That is, the backhaul communication unit converts a bit string transmitted from the base station to other nodes, such as other access nodes, other base stations, upper nodes, and core networks, into a physical signal, and converts a physical signal received from other nodes into a bit string.

[0048] The storage unit 220 stores data such as basic programs, application programs, and setting information for the operation of the DU 160. The storage unit 220 may include a memory. The storage unit 220 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The storage unit 220 provides the stored data in response to a request from the control unit 230.

[0049] The controller 230 controls the overall operation of the DU 160. For example, the controller 230 transmits and receives signals via the communication unit 210 (or via the backhaul communication unit). The controller 230 also records and reads data in the memory unit 220. The controller 230 can perform a protocol stack function required by a communication standard. To this end, the controller 230 can include at least one processor. In some embodiments, the controller 230 can include a control message generator that generates a control plane message having an extension field including a regularization factor, and a management message generator that generates a management message for deactivating a regularization factor field of a message including an existing regularization factor (e.g., a control plane message of Section Type 6 of O-RAN). The control message generator and the management message generator may be a set of instructions or codes stored in the memory unit 230, instructions / codes that at least temporarily reside in the control unit 230, or a memory space that stores instructions / codes, or may be part of the circuitry that constitutes the control unit 230. According to various embodiments, the control unit 230 may control the DU 160 to perform operations according to various embodiments described below.

[0050] The configuration of the DU 160 shown in Fig. 2 is merely an example, and examples of the DU performing various embodiments of the present disclosure are not limited to the configuration shown in Fig. 2. That is, according to various embodiments, some configurations may be added, deleted, or changed.

[0051] Fig. 3 shows a configuration of an RU in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in Fig. 3 may be understood as a part of a base station and as a configuration of RU 180 in Fig. 1B. As used below, the terms "unit", "device", etc. refer to a unit that processes at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

[0052] Referring to FIG. 3, the RU 180 includes a communication unit 310 , a storage unit 320 , and a control unit 330 .

[0053] The communication unit 310 performs a function of transmitting and receiving signals through a wireless channel. For example, the communication unit 310 up-converts a baseband signal to an RF band signal and transmits the signal through an antenna, and down-converts an RF band signal received through the antenna to a baseband signal. For example, the communication unit 310 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0054] Also, the communication unit 310 may include a number of transmission and reception paths. Furthermore, the communication unit 310 may include an antenna unit. The communication unit 310 may include at least one antenna array including a number of antenna elements. In terms of hardware, the communication unit 310 may be configured with a digital circuit and an analog circuit (e.g., RFIC (radio frequency integrated circuit)). Here, the digital circuit and the analog circuit may be implemented in one package. Also, the communication unit 310 may include a number of RF chains. The communication unit 310 may perform beamforming. The communication unit 310 may apply a beamforming weight to a signal to be transmitted or received in order to give the signal directivity according to the setting of the control unit 330. According to an embodiment, the communication unit 310 may include an RF (radio frequency) block (or RF unit).

[0055] In addition, the communication unit 310 can transmit and receive signals. To this end, the communication unit 310 can include at least one transceiver. The communication unit 310 can transmit downlink signals. The downlink signals can include a synchronization signal (SS), a reference signal (RS) (e.g., CRS (cell-specific reference signal), DM (demodulation)-RS), system information (e.g., MIB, SIB, RMSI (remaining system information), OSI (other system information)), a configuration message, control information, downlink data, etc. In addition, the communication unit 310 can receive uplink signals. 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), etc.

[0056] The communication unit 310 transmits and receives signals as described above. Therefore, all or part of the communication unit 310 can be referred to as a "transmitter," a "receiver," or a "transmitter / receiver." In the following description, transmission and reception via a wireless channel are used to mean that the above-mentioned processing is performed by the communication unit 310.

[0057] The storage unit 320 stores data such as basic programs, application programs, and setting information for the operation of the RU 180. The storage unit 320 may be configured as a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The storage unit 320 provides the stored data in response to a request from the control unit 330. According to an embodiment, the storage unit 320 may include a channel memory for updating channel information without a separate memory for storing regularization parameter-related information in real time.

[0058] The controller 330 controls the overall operation of the RU 180. For example, the controller 330 transmits and receives signals via the communication unit 310. The controller 330 also records and reads data in the storage unit 320. The controller 330 can perform a protocol stack function required by a communication standard. To this end, the controller 330 can include at least one processor. In some embodiments, the controller 230 can include a control message interpretation unit for interpreting a control plane (C-plane) message having an extension field including a regularization factor, and a management message interpretation unit for interpreting a management plane (M-plane) message for deactivating a regularization factor field of a message including an existing regularization factor (e.g., a control plane message of Section type 6 of O-RAN). The control message interpretation unit and the management message interpretation unit may be a command set or code stored in the memory unit 320, and may be a command / code or a memory space for storing command / code that at least temporarily resides in the control unit 330, or may be a part of a circuit that constitutes the control unit 330. The control unit 330 may include various modules for performing communication. According to various embodiments, the control unit 330 may control the terminal to perform operations according to various embodiments described below.

[0059] FIG. 4 illustrates an example of function split in a wireless communication system according to various embodiments of the present disclosure. As wireless communication technology develops (e.g., 5G (5 th With the introduction of the 5G (new generation) communication system (or the NR (new radio) communication system), the number of RUs required to be installed has increased as the frequency bands used have increased and the cell radius of base stations has become very small. In addition, the amount of data transmitted in the 5G communication system has increased by more than 10 times, and the transmission capacity of the wired network transmitted in the fronthaul has increased significantly. Due to these factors, the installation cost of the wired network in the 5G communication system may increase significantly. Therefore, in order to reduce the transmission capacity of the wired network and reduce the installation cost of the wired network, a technology has been proposed to transfer some of the functions of the DU modem to the RU to reduce the transmission capacity of the fronthaul, and this technology can be called "function split."

[0060] In order to reduce the burden on the DU, a method is being considered to expand the role of the RU, which is responsible for only RF functions, to some of the physical layer functions. In this case, the higher the layer function the RU performs, the higher the RU's processing volume increases, the greater the transmission bandwidth in the fronthaul, and the lower the constraints on latency requirements due to response processing. On the other hand, the higher the layer function the RU performs, the less the virtualization gain is, and the larger / weight / cost of the RU increases. It is necessary to implement optimal functional separation by considering the trade-off between the above advantages and disadvantages.

[0061] Referring to FIG. 4, functional separation in the physical layer below the MAC layer is illustrated. In the case of a downlink (DL) transmitting a signal to a terminal via a wireless network, a base station may sequentially perform channel encoding / scrambling, modulation, layer mapping, antenna mapping, RE mapping, digital beamforming (e.g., precoding), IFFT transformation / CP insertion, and RF conversion. In the case of an uplink (UL) receiving a signal from a terminal via a wireless network, a base station may sequentially perform RF conversion, FFT transformation / CP removal, digital beamforming (pre-combining), RE demapping, channel estimation, layer demapping, demodulation, and decoding / descrambling. The separation of the uplink function and the downlink function may be defined into various types according to the needs of vendors, standard discussions, etc., depending on the above-mentioned trade-off.

[0062] The first function separation 405 may be a separation of an RF function and a PHY function. The first function separation is such that the PHY function is not actually implemented in the RU, and may be referred to as Option 8, for example. The second function separation 410 is such that the RU performs IFFT conversion / CP insertion in DL and FFT conversion / CP removal in UL of the PHY function, and the DU performs the remaining PHY functions. For example, the second function separation 410 may be referred to as Option 7-1. The third function separation 420a is such that the RU performs IFFT conversion / CP insertion in DL of the PHY function, and FFT conversion / CP removal and digital beamforming in UL, and the DU performs the remaining PHY functions. For example, the third function separation 420a may be referred to as Option 7-2x Category A. The fourth function separation 420b is such that the RU performs up to digital beamforming in both DL and UL, and the DU performs higher PHY functions after digital beamforming. For example, the fourth function separation 420b may be referred to as Option 7-2x Category B. In the fifth function separation 425, the RU performs up to RE mapping (or RE demapping) in both DL and UL, and the DU performs higher PHY functions after RE mapping (or RE demapping). As an example, the fifth function separation 425 may be referred to as Option 7-2. In the sixth function separation 430, the RU performs up to modulation (or demodulation) in both DL and UL, and the DU performs higher PHY functions after modulation (or demodulation). As an example, the sixth function separation 430 may be referred to as Option 7-3. In the seventh function separation 440, the RU performs up to encoding / scrambling (or decoding / descrambling) in both DL and UL, and the DU performs higher PHY functions after modulation (or demodulation). As an example, the seventh function separation 440 may be referred to as Option 6.

[0063] According to an embodiment, when large-capacity signal processing is expected, such as in the FR1 MMU, functional separation at a relatively high layer (e.g., fourth functional separation 420b) may be required to reduce the fronthaul capacity. In addition, since functional separation at an excessively high layer (e.g., sixth functional separation 430) may complicate the control interface and include many PHY processing blocks in the RU, which may cause a burden on the implementation of the RU, appropriate functional separation may be required depending on the arrangement and implementation method of the DU and RU.

[0064] According to an embodiment, when the precoding of data received from the DU cannot be processed (i.e., when 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, when the precoding of data received from the DU can be processed, the fourth functional separation 420b or a higher functional separation (e.g., the sixth functional separation 430) may be applied. Hereinafter, various embodiments in the present disclosure will be described based on the third functional separation 420a or the fourth functional separation 420b for performing beamforming processing in the RU unless otherwise limited, but the configuration of an embodiment according to another functional separation is not excluded. The configuration / operation flow of the control plane message, management plane message, or other device of FIG. 5A to FIG. 11 described later may be applied to not only the third functional separation 420a or the fourth functional separation 420b but also other functional separations.

[0065] In various embodiments of the present disclosure, eCPRI and O-RAN standards are exemplified as a fronthaul interface when transmitting a message between a DU (e.g., DU 160 in FIG. 1B) and an RU (e.g., RU 180 in FIG. 1B). An eCPRI header, an O-RAN header, and additional fields may be included in the Ethernet payload of the message. Hereinafter, various embodiments of the present disclosure will be described using eCPRI or O-RAN standard terminology, but other expressions having equivalent meanings to each term may be used instead of various embodiments of the present disclosure.

[0066] The fronthaul transport protocol may use Ethernet and eCPRI, which are easy to share with the network. The eCPRI header and O-RAN header may be included in the Ethernet payload. The eCPRI header may be located at the front end of the Ethernet payload. The contents of the eCPRI header are as follows:

[0067] ecpriVersion (4 bits): 0001b (fixed value) ecpriReserved (3 bits): 0000b (fixed value) ecpriConcatenation (1 bit): 0b (fixed value) ecpriMessage (1 byte): Message type ecpriPayload (2 bytes): Payload size in bytes ecpriRtcid / ecpriPcid (2 bytes): x, y, z can be configured by the management plane (M-plane). This field can indicate the transmission path of a control message according to various embodiments during multi-layer transmission (eAxC (extended Antenna-carrier) in eCPRI).

[0068] CU_Port_ID(x bits): Identifies the channel card. Can also identify the modem (2 bits for channel card, 2 bits for Modem) BandSector_ID(y bits): Division by Cell / Sector CC_ID(z bits): Classified by component carrier RU_Port_ID(w bits): Classified by layer, T, antenna, etc. ecpriSeqid (2 bytes): Sequence ID is managed separately for ecpriRtcid / ecpriPcid, and sequence ID and subsequence ID are managed separately. Radio-transport-level fragmentation is possible by using subsequence ID (different from application-level fragmentation). Fronthaul application protocols may include a control plane (C-plane), a user plane (U-plane), a synchronization plane (S-plane), and a management plane (M-plane).

[0069] The control plane may be configured to provide scheduling information and beamforming information by control messages. The user plane may include a user's downlink data (IQ data or SSB / RS), uplink data (IQ data or SRS / RS), or PRACH data. The weight vector of the beamforming information mentioned above may be multiplied to the user's data. The synchronization plane may be associated with timing and synchronization. The management plane may be associated with initial setup, non-realtime reset or reset, and non-realtime report. Section types are defined to define the types of messages transmitted in the control plane. Section types can indicate the purpose of a control message transmitted in the control plane. For example, the purposes of each section type are as follows:

[0070] sectionType=0: DL idle / guard periods - Used for Tx blanking for power saving sectionType=1: BF index or weight (O-RAN mandatory BF method) is mapped to RE of DL / UL channel sectionType=2:reserved sectionType=3: Mapping beamforming index or weight to RE of PRACH and mixed-numerology channel sectionType=4:reserved sectionType=5: Transmits UE scheduling information so that the RU can perform real-time BF weight calculation (O-RAN optional BF method) sectionType=6: Periodically transmits UE channel information so that the RU can perform real-time BF weight calculation (O-RAN optional BF method) sectionType=7: Used for LAA support

[0071] When an RU communicates with a UE using beamforming, the RU requires information on the current channel and scheduling information. That is, the RU is required to obtain a Section Type 5 control message and a Section Type 6 control message. The RU can identify whether or not the UE has slot-specific scheduling from the Section Type 5 control message, and can identify information on the current channel state from the Section Type 6 control message. The Section Type 6 control message may be transmitted periodically. The channel information may be transmitted periodically so that the RU can calculate the beamforming weight for each slot. An example of a control message according to Section type 6 is described below with reference to FIG. 5A.

[0072] 5A shows an example of a control message according to Section type 6. A control message according to Section type 6 is configured for carrying channel information.

[0073] 5A, a control message of Section type 6 may include a transport header 501, a common header 503, first section information 505, and second section information 507. The transport header 501 may include a header according to eCPRI or IEEE.

[0074] The common header 503 is a common radio application header and may include parameters such as:

[0075] dataDirection (data direction (gNB Tx / Rx)) field: 1 bit payloadVersion (payload version) field: 3 bits value = “1” shall be set (1 st protocol version for payload and time reference format) filterIndex (filter index) field: 4 bits, frameId (frame identifier) ​​field: 8 bits subframeId (subframe identifier) ​​field: 4 bits slotID (slot identifier) ​​field: 6 bits startSymbolid (start symbol identifier) ​​field: 6 bits numberOfsections (number of sections) field: 8 bits sectionType (section type) field: 8 bits, value = 6 numberOfUEs (number of UE-specific channel information data sets) field: 8 bits reserved (reserved for future use) field: 8 bits

[0076] The first section information 505 and the second section information 507 may be configured for each UE. For example, the first section information 505 may be configured for a first UE, and the second section information may be configured for a second UE. Although the following description will be based on the first section information 505, the same or a similar format may be applied to the second section information 507. The first section information 505 may include the following parameters:

[0077] ef (extension flag) field: 1 bit ueId (UE identifier) ​​field: 15 bits regularizationFactor (regularization factor used for MMSE reception) field: 16 bits reserved (reserved for future use) field: 4 bits rb (resource block identifier) ​​field: 1 bit symInc (symbol number increment command) field: 1 bit startPrbc (starting PRB of data section description) field: 10 bits numPrbc (number of contiguous PRBs per data section description) field: 8 bits ciIsample (channel information value, in-phase sample) field: 16 bits ciQsample (channel information value, quadrature sample) field: 16 bits

[0078] Here, 'regularizationFactor' is a parameter defined in the control message of Section Type 6 and is transmitted periodically. 'regularizationFactor' can provide a signaled value to support minimum mean square error (MMSE) operation in the RU when beamforming weights are supported in the RU (e.g., UL in Option 7-2x Category A (e.g., third function separation 420a in FIG. 4) or DL / UL in Option 7-2x Category B (e.g., fourth function separation 420b in FIG. 4). 'regularizationFactor' indicates the above value in 2 bytes (i.e., 16 bits).

[0079] According to various embodiments of the present disclosure, the regularization parameter indicated by 'regularizationFactor' may be used to derive the beamforming weights. For example, the relationship between the regularization parameter and the beamforming weights may be derived based on the following formula:

number

number

number

[0080] For example, the beamforming weights may be derived based on the channel covariance parameters, and the relationship between the channel covariance parameters and the regularization parameters may be derived based on the following equation:

number

[0081] Hereinafter, the present disclosure will describe messages, signaling, and DU / RU devices and methods for efficient processing of the above-mentioned regularization parameter ('regularizationFactor'). In this disclosure, the regularization parameter may be referred to as a regularization factor, regularization information, regularization element, etc. Also, the embodiment of the present disclosure will be described using an example of the regularization parameter 'regularizationFactor' of Section Type 6 as a 2-byte value, but it can be understood that the regularization parameter may be modified to a form (e.g., 3-byte) that is easy for a person skilled in the art to implement in terms of data size / calculation method as an embodiment of the present disclosure.

[0082] 5B shows an example of a functional configuration of an RU for beamforming information processing. The RU may include a channel memory 521 and a regularization factor memory 523.

[0083] Referring to FIG. 5B, the channel memory 521 can obtain channel information from a control message of Section Type 6. The RU can store the channel information in the channel memory 521. The channel information can be periodically updated. For example, the channel information can be 'ciIsample(Ci)' or 'ciQsample(Cq)' of Section Type 6, or can include a value obtained therefrom. Ci indicates an I value of complex channel information, and Cq indicates a Q value of complex channel information. The regularization factor memory 523 can obtain information on regularization parameters from a control message of Section Type 6. The regularization parameters are transmitted (updated) together with the channel information transmitted (updated) to the C-plane Section Type 6. The RU can store information on regularization parameters in the regularization factor memory 523. At this time, the information on the regularization parameters can be periodically updated. For example, the information on the regularization parameters can be 'regularization factor' of Section Type 6, or can include a value obtained therefrom. The regularization factor memory 523 can store information on regularization parameters in the regularization factor memory 523. At this time, the information on the regularization parameters can be periodically updated. For example, the information on the regularization parameters can be 'regularization factor' of Section Type 6, or can include a value obtained therefrom. The regularization factor memory 523 can store information on regularization parameters in the regularization factor memory 523. nn It can be called memory (e.g. R nn is the regularization parameter value in Eq. 2).

[0084] The control message of Section Type 5 includes scheduling information of the UE. Scheduling may be performed in a specified unit (e.g., slot unit). The scheduling information may be provided to the regularization factor memory 523 repeatedly for each slot. Since information on the regularization parameters is delivered together with the channel information, the RU may include a regularization factor memory 523 having the same dimension as the channel memory 521, which is a memory that stores the channel information. The RU may obtain the corresponding channel value and regularization parameter value from each memory according to the scheduling information (e.g., the control message of Section Type 5) delivered for each slot, and calculate the beamforming weight value. Specifically, the RU may obtain the channel information from the channel memory 521 and the regularization parameter from the regularization factor memory 523 to calculate the beamforming weight value. The RU may calculate and obtain the beamforming weight value (or the MU (multi-user) weight value) for MMSE (or ZFBF) for the current channel based on the regularization parameter and the channel information.

[0085] At this time, although it is sufficient that the beamforming weights are calculated only when the UE is scheduled, the regularization factor memory 523 periodically acquires and stores channel information and regularization parameters in addition to the scheduling information acquired each time the corresponding UE is scheduled. When the terminal is actually scheduled, the most recently transmitted regularization parameter value must be used, so the regularization factor memory 523 must store all transmitted regularization parameter values ​​even if they are not actually used. Therefore, the information on the regularization parameters that is repeatedly stored even when the UE is not actually scheduled causes a burden on the regularization factor memory 523. In addition, if the channel information is updated for a relatively long period compared to the scheduling information updated every slot (e.g., 0.5 ms), the regularization parameters of Section Type 6 are more likely to not correctly reflect the channel that the terminal actually experiences. A specific example will be described with reference to FIG. 5C.

[0086] FIG. 5C shows the relationship between the regularization factor and scheduling.

[0087] Referring to FIG. 5C, the upward arrow indicates that the 'regularization factor' of the Section Type 6 control message for UE #3 is transmitted. The control message transmission period 540 may be 40 ms. Multiple UEs may be scheduled. In this case, UE #3 may be scheduled at the front end 551 and rear end 553 within the 40 ms period 540.

[0088] When UE #3 is scheduled at the front end 551, a relatively short time has passed since the channel information of Section Type 6 was updated, so the RU can derive beamforming weights that are more consistent with the actual channel. However, when UE #3 is scheduled at the rear end 553, a relatively long time has passed since the channel information of Section Type 6 was updated, so the RU has difficulty deriving beamforming weights that are more consistent with the actual channel. This is because the channel changes over time, which creates a difference between the actual channel and the channel that appears in the channel information transmitted through the DU. This problem occurs when the transmission period of the Section Type 6 control message is longer, which creates a larger error, and this error generates an inaccurate beamforming weight, resulting in a decrease in transmission performance.

[0089] Hereinafter, various embodiments of the present disclosure will describe a method for transmitting a regularization parameter together with transmission of scheduling information instead of periodically transmitting the regularization parameter in order to solve the problems described through Figures 5A to 5C. Also, various embodiments of the present disclosure will describe a method for processing the periodically transmitted 'regularizationFactor' of Section Type 6 defined in the existing O-RAN standard in order to satisfy backward compatibility. Also, various embodiments of the present disclosure will describe a new functional implementation method for the RU in order to avoid memory burden in storing periodically transmitted information.

[0090] In addition, in the present disclosure, not only the transmission of scheduling / channel information for a 5G communication system (e.g., NR) but also the implementation for a 4G communication system (e.g., LTE) can be understood as an embodiment of the present disclosure. That is, the communication system in which the DU and RU operations described below are provided is not limited to only the 5G communication system, nor is it limited to only the 4G communication system.

[0091] 6 shows an example of an extension field according to various embodiments of the present disclosure. When a DU transmits a control message according to an existing section type, the DU can transmit additional information along with the control message by using the extension field. That is, the DU can transmit a control message on the control plane section by attaching a new extension field, 'section extension'.

[0092] 6, a section extension field 600 according to various embodiments may include information on a regularization parameter. The regularization parameter may be a value corresponding to 'regularizationFactor' of Section Type 6. -extType may indicate a type for the additional parameters. According to one embodiment, if extType indicates 11, extType may indicate that the additional parameters include a regularization factor value for MMSE (or ZFBF). Of course, the value of '11' is exemplary, and other numbers may be assigned to specify the type for the parameters.

[0093] -ef can indicate the presence or absence of an additional section extension field. A value of '1' for ef indicates the presence of an additional section extension field, and a value of '0' for ef indicates the absence of an additional section extension field.

[0094] -extLen may indicate the length of the section extension field in 4-byte units. According to one embodiment, extLen may indicate 1.

[0095] According to various embodiments, a section extension field including a regularization parameter may be attached to a control message including scheduling information (e.g., a control plane message of Section Type 5 of O-RAN) and transmitted together. By the DU transmitting the regularization parameter together with the scheduling information, a problem that the actual channel state cannot be reflected when calculating the beamforming weight due to the difference between the scheduling time and the transmission time of the regularization parameter may be resolved.

[0096] Although not shown in FIG. 6, a section extension field including channel information may be defined. For example, a section extension field including channel information (e.g., ciIsample, ciQsample) in a control message of Section Type 6 may be defined. The channel information in the section extension field may be configured for each antenna and frequency resource (e.g., PRB, PRB group, BWP (bandwidth part), etc.). By considering the capability of the terminal that the RU intends to serve and / or the rank information of the terminal, the DU can obtain the required number of antennas from among all antennas. In addition, the DU can identify the frequency domain that is actually served to the terminal from among the resources of the entire frequency domain when a relatively small amount of channel information is required depending on the type of communication method (e.g., LTE) or by considering the scheduling domain for a specific terminal.

[0097] In some embodiments, the channel information may include channel information for each of the entire antennas and each of the entire PRBs. In some other embodiments, the channel information may include channel information for each of a portion of the entire antennas and each of a portion of the entire PRBs. In some other embodiments, the channel information may include channel information for each of a portion of the entire antennas and each of the entire PRBs. In some other embodiments, the channel information may include channel information for each of the entire antennas and each of the portion of the PRBs. In some other embodiments, the channel information may include channel information for each of the entire antennas and each of the portion of the PRBs. According to one embodiment, by transmitting channel information for an actual scheduling region of the terminal, a relatively small amount of channel information can be configured as a section extension field.

[0098] Instead of being transmitted periodically as in Section Type 6, the channel information can be transmitted to the RU in the form of a section extension field, attached to Section Type 5 in which scheduling information is transmitted. As with the regularization parameter, it is provided at the time of actual scheduling of the UE, thereby resolving the problem of communication performance degradation due to the difference between the time of transmitting channel information and the time of actual scheduling. Furthermore, when accurate channel information is required non-periodically as needed, the section extension field allows the RU to obtain optimal beamforming weights.

[0099] According to one embodiment, the section extension field including channel information may be configured as shown in the following table. The section extension field including channel information may be attached to a control message including scheduling information of a terminal (UE) (e.g., a control message of Section Type 5 of the C-plane) and transmitted. [Table 1]

[0100] According to an embodiment, the section extension field including channel information may be configured as shown in the following table. The section extension field including channel information may include information on 'regularizationFactor', i.e., regularization parameter. The section extension field including both channel information and regularization parameter information may be attached to a control message including scheduling information of a terminal (UE) (e.g., a control message of Section Type 5 of C-plane) and transmitted. [Table 2]

[0101] In Tables 1 and 2, the channel information is exemplified as ciIsample and ciQsample for one antenna / one PRB, but various embodiments of the present disclosure are not limited thereto. Section extension fields may be defined for a greater number of antennas or a greater number of PRBs. As an example, the length for ciIsample and ciQsample may be variable and may be set by M-plane.

[0102] Meanwhile, even if the regularization parameter is delivered together with the scheduling information by the section extension field, the regularization parameter delivered by the control message of Section Type 6 of the existing standard (e.g., O-RAN 2.00) is periodically delivered to the RU. Since the regularization parameter is delivered periodically to the memory of the RU, the control message of Section Type 6 is still a burden. Hereinafter, various embodiments of the present disclosure propose a method for reducing the influence of 'regularizationFactor' of the control message of Section Type 6 while satisfying backward compatibility with the existing standard.

[0103] FIG. 7 illustrates an example of a management message for Section type 6 according to various embodiments of the present disclosure. The management message refers to a message transmitted in the management plane (M-plane) of O-RAN. The DU can perform packet communication with the RU in a management area in a main card. The management message can be transmitted from the DU to the RU or from the RU to the DU. In the management plane, "start up" installation, software management, configuration management, performance management, fault management, and file management can be performed.

[0104] Referring to FIG. 7, a DU may generate a management message. According to various embodiments, the management message may be a message for setting the 'regularization factor' of a Section Type 6 control message to an invalid RU. In some embodiments, the management message may include a parameter (hereinafter, a selection parameter) for instructing a selection of a transmission medium. The selection parameter may indicate whether the regularization parameter is transmitted by a Section Type 6 message of the control plane as in the past, or the regularization parameter is transmitted by a section extension field. As an example, a value of '0' of the selection parameter may indicate the transmission of the regularization parameter by a Section Type 6 message. A value of '1' of the selection parameter may indicate the transmission of the regularization parameter by a section extension field. In this case, when the value of the selection parameter indicates the transmission of the regularization parameter by the section extension field, the regularizationFactor value in the Section Type 6 control message is invalid. An RU that receives a management message including the above selection parameter value may not take into account the regularizationFactor value of Section Type 6. As an example, the RU may ignore or discard the regularizationFactor value of Section Type 6 that is transmitted periodically. Also, as an example, the RU may not consider the regularizationFactor value for a specified period of time.

[0105] The DU can transmit a management message to the RU. The RU can identify how to obtain the regularization parameters from the management message. For example, the RU can obtain the regularization parameters from the section extension field. As another example, the RU can obtain the regularization parameters from Section Type 6.

[0106] Although not shown in FIG. 7, for backward compatibility, fields in the existing Section Type 6 may be utilized. In some embodiments, if 'regularizationFactor' indicates a specific value (e.g., 1111 1111 1111 1111), the field value of 'regularizationFactor' may be an invalid value. The RU may ignore or discard the corresponding 'regularizationFactor' without storing it. In some other embodiments, if at least one bit in the reserved bits of the fields in the existing Section Type 6 indicates a specific value (e.g., 1), the field value of 'regularizationFactor' may be an invalid value. The RU may ignore or discard the corresponding 'regularizationFactor' without storing it. In still other embodiments, a combination of at least two of the fields in the existing Section Type 6 may indicate that the field value of 'regularizationFactor' is an invalid value.

[0107] According to various embodiments, in a situation where it is difficult to transmit a message (e.g., a Section Type 6 control message) periodically transmitting channel information (e.g., when the memory allocation amount of the RU is excessively large or the RU's capacity is insufficient) or when the transmission capacity of the fronthaul is sufficiently large, the DU can transmit additional information through the section extension field together with the scheduling information. In this case, the additional information can include information replacing the information in the Section Type 6 control message. For example, the additional information can include channel information. Also, for example, the additional information can include information on a regularization parameter. The DU can replace Section Type 6 with a Section Type 5 control message by transmitting the additional information through the section extension field.

[0108] 8A illustrates a flow of operations of a DU for an extension field according to various embodiments of the present disclosure. The DU is exemplified by the DU 160 in FIG.

[0109] Referring to FIG. 8A, in operation 801, the DU may configure a section extension field including a regularization parameter. Here, the regularization parameter may be a parameter for deriving a beamforming weight. The beamforming weight may be a matrix that is set so that an effective channel matrix experienced by a transmitted signal can smoothly reach a receiving end. According to an embodiment, the beamforming weight may be derived based on MMSE or zero-forcing beamforming (ZFBF). As an example, the beamforming weight may be derived according to Equation 1 above. Such a regularization parameter may be a value indicated by a 'regularizationFactor' field in a control message of Section Type 6 of the O-RAN standard.

[0110] In operation 803, the DU may transmit a control message for scheduling including a section extension field to the RU. The DU may configure the control message for scheduling. That is, the DU may generate a message including scheduling information of the UE in a C-plane control message. For example, the DU may generate a control message of Section Type 5. The DU may attach an extension section field to the control message. Here, the extension section field may be the section extension field set in operation 801. The DU may transmit the control message to the RU via the fronthaul interface. That is, the control message for scheduling may convey both scheduling information for the UE and regularization parameters for the channel to the RU.

[0111] 8B illustrates an operational flow of an RU for an extension field according to various embodiments of the present disclosure. The RU is exemplified by RU 180 of FIG.

[0112] Referring to Figure 8B, in operation 851, the RU may receive a control message for scheduling. The control message may include scheduling information for the UE. For example, the control message may correspond to a message of Section Type 5 of the C-plane of the O-RAN. The RU may receive the control message from the DU via a fronthaul interface.

[0113] At operation 853, the RU can identify the regularization parameters from a section extension field in the control message. The RU can identify a section extension field in the control message. The RU can determine what information is included in the section extension field from type information (e.g., extType) of the section extension field. The RU can determine that the section extension field includes regularization parameters from a specified type value. The RU can identify the regularization parameters. As an example, the regularization parameters may be represented as a 2-byte value.

[0114] In operation 855, the RU may obtain beamforming weights. The beamforming weights may be beamforming weights for a multi-user (MU). The RU may derive the beamforming weights based on the regularization parameters obtained in operation 853. For example, the RU may derive the beamforming weights based on Equation 1. For example, the RU may derive the beamforming weights based on Equation 2. nn The beamforming weights can be derived from the values.

[0115] Meanwhile, although not shown in Figures 8A and 8B, channel information may be additionally included in a control message for scheduling, where the channel information may be I / Q data for complex channel information on resources (e.g., x PRB, where x is an integer equal to or less than 273) allocated to a terminal antenna / terminal.

[0116] 8A to 8B, a method for reducing errors due to differences in the acquisition time of channel information and improving transmission performance by adding an extension field to a control message including channel information and transmitting the regularization parameters included in the existing Section Type 6 is described. However, if the regularization parameters are transmitted by the extension section field without separate processing for the regularization parameters of Section Type 6, there is a problem that the working capacity in the memory of the RU becomes excessively bulky. Specifically, since Section Type 6 is transmitted periodically and scheduling is performed in a unit that is much shorter than the period, a problem occurs in that channel information (e.g., channel information, regularization parameters) must be stored for each scheduling unit during the period in order to reflect real-time channel information and calculate beamforming weights. Therefore, a method for deactivating (or invalidating) the regularization parameters of the existing Section Type 6 control message that is transmitted periodically is described.

[0117] 9A illustrates the operation flow of a DU for a management message for Section type 6 according to various embodiments of the present disclosure. The DU is exemplified by the DU 160 in FIG.

[0118] Referring to FIG. 9A, in operation 901, the DU may transmit a management message for the regularization parameter. The DU may transmit the management message to the RU via a fronthaul interface. The management message may be a message transmitted from the DU to the RU on the M-plane. The management message may be a non-real-time message and may be transmitted on the main card of the DU. The management message for the regularization parameter may be a message indicating a method for the RU to acquire the regularization parameter. In some embodiments, the management message may indicate whether the regularization parameter is transmitted by a section extension field or by a control message for channel information. For example, the management message may include one bit. The one bit may indicate a transmission method of the regularization parameter. For example, a value of '1' of the one bit may indicate that the regularization parameter is transmitted by a section extension field. A value of '0' of the one bit may indicate that the regularization parameter is transmitted by a control message (C-plane) of Section type 6.

[0119] Alternatively, in some embodiments, the management message may include information regarding the validity of the regularization parameter of the control message for channel information. For example, the management message may indicate the validity of 'regularizationFactor' in the control message of Section Type 6 with 1 bit. A value of '1' may indicate that the regularization parameter in Section Type 6 is not valid. A value of '1' may implicitly indicate that the regularization parameter is conveyed by the section extension field. A value of '0' may indicate that the regularization parameter in Section Type 6 is valid.

[0120] Alternatively, in some embodiments, the management message may include information regarding the validity of the regularization parameter in the extension section field. For example, the management message may indicate the validity of the 'regularizationFactor' in the extension section field with 1 bit. A value of '1' may indicate that the regularization parameter in the extension section field is not valid. A value of '1' may implicitly indicate that the regularization parameter is transmitted via Section Type 6. A value of '0' may indicate that the regularization parameter in the section extension field is valid. Alternatively, for example, the management message may include information regarding the validity period of the regularization parameter in the extension section field. The regularization parameter in the control message of Section type 6 may be set to default, and the regularization parameter in the extension section field may be provided to the RU as necessary. In this case, only the regularization parameter in the extension section field may be received during the validity period according to the management message, and the regularization parameter in the control message of Section Type 6 may be ignored or discarded.

[0121] In operation 903, the DU may transmit a control message for channel information including the regularization parameter. The DU may transmit the control message to the RU via a fronthaul interface. The control message may be configured to include the channel information and may be periodically transmitted from the DU to the RU. For example, the control message may be a message of Section Type 6 of O-RAN, and the regularization parameter may be 'regularizationFactor'.

[0122] The DU sets the availability of the regularization parameters for the channel to the RU through a management message, so that the RU can efficiently process the regularization parameters even if the DU transmits a management message as in the existing standard, i.e., backward compatibility can be satisfied.

[0123] 9B illustrates an operational flow of an RU for a management message for Section type 6 according to various embodiments of the present disclosure. The RU illustrates the RU 180 of FIG.

[0124] Referring to FIG. 9B, in operation 951, the RU may receive a management message for the regularization parameter. The RU may receive the management message from the DU via a fronthaul interface. The management message is a message transmitted in the M-plane and may be transmitted in the main card of the DU. The management message for the regularization parameter may include information regarding a transmission method of the regularization parameter. In some embodiments, the management message may indicate whether the regularization parameter is transmitted by the section extension field or by the control message for channel information. In some embodiments, the management message may include information regarding the validity of the regularization parameter of Section Type 6. In some embodiments, the management message may include information regarding the validity of the regularization parameter transmitted by the section extension field.

[0125] In operation 953, the RU may identify a transmission method of the regularization parameter. The RU may identify a transmission method of the regularization parameter based on a management message received from the DU. For example, the RU may acquire the regularization parameter only through a control message for channel information (e.g., a control message of Section Type 6). Also, for example, the RU may acquire the regularization parameter only through a section extension field. Also, for example, the RU may acquire the regularization parameter through at least one of the section extension field or the control message for channel information.

[0126] In operation 955, the RU may receive a control message for channel information, including the regularization parameter. The RU may receive the control message from the DU via a fronthaul interface. The RU may determine whether the control message for channel information allows acquisition of the regularization parameter. If the control message for channel information allows acquisition of the regularization parameter, the RU may acquire the regularization parameter from the control message (e.g., a control message of Section Type 6). The RU may determine beamforming weights based on the acquired regularization parameter.

[0127] If the control message for channel information does not allow the RU to obtain the regularization parameter, the RU may ignore or discard the regularization parameter in the control message for channel information (e.g., a control message of Section Type 6). According to one embodiment, when the RU receives scheduling information, the RU may obtain the regularization parameter from an extension field in the control message including the scheduling information. The RU may determine beamforming weights based on the obtained regularization parameter.

[0128] Although not shown in Figures 9A and 9B, in addition to the management message, a control message may be used to indicate a method of transmitting a regularization parameter. The management message may be transmitted from the main card of the DU to the RU, and the control message may be transmitted from the channel card of the DU to the RU. The control message may be transmitted in real time relatively compared to the management message. According to an embodiment, some fields of the control message of Section Type 6 or some values ​​of 'regularizationFactor' may indicate that 'regularizationFactor' in the corresponding control message is invalid.

[0129] 10 illustrates an example of a functional configuration of an RU for beamforming information processing according to various embodiments of the present disclosure. The RU may include a channel memory 1021.

[0130] Referring to FIG. 10, the channel memory 1021 can obtain channel information from a control message of Section Type 6. The RU can store the channel information in the channel memory 1021. The channel information can be updated periodically. For example, the channel information can be 'ciIsample(Ci)' or 'ciQsample(Cq)' of Section Type 6, or can include a value obtained therefrom. Ci indicates an I value of the complex channel information, and Cq indicates a Q value of the complex channel information. At this time, the RU can ignore or discard information on the regularization parameter in the control message of Section Type 6. The RU can identify that the regularization parameter in the control message of Section Type 6 is invalid. According to an embodiment, the RU can identify that the regularization parameter in the control message of the control plane of Section Type 6 is invalid based on a management message of the management plane from the DU. Also, according to an embodiment, the RU can identify that the regularization parameter in the control message of Section Type 6 is invalid based on a control message of the DU.

[0131] The RU can transmit scheduling information of Section Type 5 to the channel memory 1021. The channel memory 1021 stores the scheduling information in slot units (scheduling units), and the result of the channel information can be used when calculating beamforming weights. The channel memory 1021 outputs the channel information in slot units, and the output result can be used when calculating beamforming weights.

[0132] The RU can obtain the regularization parameter from the section extension field transmitted along with Section Type 5. Unlike the RU shown in FIG. 5B, the RU according to various embodiments may not include a regularization factor memory. That is, the RU may be configured not to store the regularizationFactor value of the periodically transmitted Section Type 6 control message. To avoid memory burden, the RU may be configured to obtain only the regularization parameter of the section extension field. Therefore, since the RU obtains the regularization parameter through the section extension field in the control message including the scheduling information, i.e., the Section Type 5 control message, the obtained regularization parameter can be used to immediately calculate the beamforming weight. This is because the UE is scheduled in the corresponding slot and is expected to immediately determine the beamforming weight.

[0133] The regularization parameter value (i.e., R nn By transmitting the regularization parameters (values) via the section extension field, the regularization parameters can be directly transmitted to the beamforming weight calculation unit without a separate memory for storing the regularization parameters (e.g., regularization factor memory 523 in FIG. 5B). The regularization parameters transmitted via the extension field correspond to the channel actually used, so that their accuracy is increased compared to the regularization parameters transmitted via the existing Section Type 6. Since the update time and the use time of the regularization parameters are almost the same, the degradation of transmission performance due to channel errors can be reduced. Furthermore, since a separate memory for storing the regularization parameters of Section Type 6 is not required, the implementation of the RU can be simplified.

[0134] Although not shown in FIG. 10, the DU or RU may further include a multiplexer (MUX). The MUX may set the regularization parameters of the extension field in the control message of Section Type 5 and the regularization parameters of the control message of Section Type 6 as inputs. The MUX may select an output based on the M-plane message. If the M-plane message allows the transmission of the regularization parameters by the section extension field, the MUX may output the regularization parameters of the control message of Section Type 5. The RU may calculate the beamforming weights based on the output regularization parameters. On the other hand, if the M-plane message does not allow the transmission of the regularization parameters by the section extension field, the MUX may output the regularization parameters of the control message of Section Type 6. The RU may calculate the beamforming weights based on the corresponding regularization parameters. The CPU of the DU that generates messages in the control plane may also provide one output to the RU via the MUX.

[0135] FIG. 11 illustrates the relationship between regularization factor and scheduling according to various embodiments of the present disclosure.

[0136] Referring to FIG. 11, the upward arrow indicates that the 'regularization factor' of the Section Type 5 control message for UE #3 is transmitted. Unlike that shown in FIG. 5C, the valid 'regularization factor' may not be transmitted periodically, but may be transmitted according to the scheduling time of UE #3. Since the regularization factor is updated just before UE #3 is scheduled, the RU can derive beamforming weights that are more consistent with the actual channel. Therefore, the RU can obtain optimal beamforming weights regardless of whether it is located at the front end 551 or rear end 553 of the scheduling period as shown in FIG. 5C.

[0137] Although not shown in FIG 11, according to one embodiment, channel information may be transmitted together with the regularization parameters by Section Type 5. By transmitting not only the regularization parameters but also actual channel state information (per antenna, per PRB), the RU can obtain beamforming weights that are more consistent with the actual channel.

[0138] 12 illustrates an example of a relationship between a DU and a RU according to a section extension field in accordance with various embodiments of the present disclosure. The section extension field in accordance with various embodiments of the present disclosure may be configured to replace a control message of Section Type 6. In some embodiments, the section extension field may include information on a regularization parameter. In some embodiments, the section extension field may include channel information.

[0139] Referring to FIG. 12, a DU may be connected to multiple RUs. In this case, the RU may be referred to as an O-RU according to the O-RAN standard. A DU may be connected to X O-RUs. A DU may be connected to O-RU #0, O-RU #1, O-RU #2, ..., to O-RU #X-1. According to an embodiment, some of the O-RUs may periodically acquire channel information via Section Type 6. Meanwhile, other parts of the O-RUs may acquire channel information via a section extension field according to various embodiments. According to an embodiment, a transmission method (e.g., a transmission method for a regularization parameter) for each O-RU, i.e., whether it is Section Type 6 or a section extension field, may be determined by a parameter of a management plane (M-plane). Depending on the parameter of the management plane, it may be possible to select whether to transmit information associated with a channel (e.g., a regularization parameter) via Section Type 6 or to transmit information associated with a channel via a section extension field including any additional information. The DU may set this for each RU via a parameter of the management plane.

[0140] 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.

[0141] In the case of a software implementation, a computer-readable storage medium may be provided that stores one or more programs (software modules). The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute a method according to the embodiments described in the claims or specification of the present disclosure.

[0142] Such 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 device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage, magnetic cassette, or in a memory configured as a combination of some or all of them. Also, each of the constituent memories may include multiple pieces.

[0143] The program may also be stored in an attachable storage device that can be accessed through a communication network such as the Internet, an Intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. Such a storage device can be accessed by an apparatus that performs an embodiment of the present disclosure through an external port. Also, a separate storage device on the communication network can be accessed by an apparatus that performs an embodiment of the present disclosure.

[0144] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in the singular or plural form according to the specific embodiments presented. However, the expressions in the singular or plural form are selected to suit the circumstances presented for the convenience of explanation, and the present disclosure is not limited to the singular or plural components, and the components expressed in the plural form may be composed in the singular form, and the components expressed in the singular form may be composed in the plural form.

[0145] Meanwhile, although the detailed description of the present disclosure has been given with respect to specific embodiments, it is of course possible to make various modifications without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined by not only the claims set forth below, but also equivalents thereto. [Explanation of symbols]

[0146] 160 DU 180RU 210 Communications Department 220 Storage section 230 Control Unit 310 Communications Department 320 Storage section 330 Control Unit

Claims

1. 1. A method performed by a distributed unit (DU) of a base station in a wireless communication system, comprising: generating a control plane message including section extension information by using Section Type 5 of the terminal scheduling information; and transmitting the control plane message to a radio unit (RU) via a fronthaul interface; The section extension information includes information indicating a regularization factor used in minimum mean square error (MMSE) calculation for generating multi-user (MU) beamforming weights for a terminal on a slot-by-slot basis.

2. The method according to claim 1, wherein the Section Type 5 is defined in an open-radio access network (O-RAN).

3. The method comprises: The method of claim 1 , further comprising the step of: sending, to the RU, a management plane message indicating that the regularizationFactor has been sent in the section extension information.

4. The method of claim 1 , wherein the regularizationFactor is transmitted from the DU to the RU instead of Section Type 6 of channel information based on the capability of the RU.

5. The method of claim 1 , wherein the regularizationFactor is related to a noise variance used in computing the MMSE.

6. The section extension information includes information regarding a type of the section extension information related to the regularization factor and information regarding a length of the section extension information, The method of claim 1 , wherein the regularizationFactor is 16 bits in length.

7. A method performed by a radio unit (RU) of a base station in a wireless communication system, comprising: receiving a control plane message from a distributed unit (DU) via a fronthaul interface using Section Type 5 regarding terminal scheduling information, the control plane message including section extension information; identifying information indicating a regularizationFactor from the section extension information; and obtaining beamforming weights based on the regularizationFactor. The regularizationFactor is a method used to calculate minimum mean square error (MMSE) to generate multi-user (MU) beamforming weights for a terminal on a slot-by-slot basis.

8. The method according to claim 7, wherein the Section Type 5 is defined in an open-radio access network (O-RAN).

9. The method comprises: The method of claim 7 , further comprising receiving a management plane message from the DU indicating that the regularizationFactor has been sent in the section extension information.

10. The method of claim 7, wherein the regularizationFactor is transmitted from the DU to the RU instead of Section Type 6 of channel information based on the capability of the RU.

11. The method of claim 7, wherein the regularizationFactor is related to the noise variance used in calculating the MMSE.

12. The section extension information includes information regarding a type of the section extension information related to the regularization factor and information regarding a length of the section extension information, The method of claim 7 , wherein the regularizationFactor is 16 bits in length.

13. A distributed unit (DU) of a base station in a wireless communication system is A transceiver; a controller coupled to the transceiver unit, The controller: The terminal is configured to generate a control plane message including section extension information by using Section Type 5 regarding terminal scheduling information, and transmit the control plane message to a radio unit (RU) via a fronthaul interface; The section extension information is a DU including information indicating a regularization factor used in minimum mean square error (MMSE) calculation to generate multi-user (MU) beamforming weights for a UE on a slot-by-slot basis.

14. The DU described in claim 13, wherein Section Type 5 is defined in an O-RAN (open-radio access network).

15. The controller: The DU of claim 13 , further configured to: send, to the RU, a management plane message indicating that the regularizationFactor has been sent in the section extension information.

16. The DU of claim 13, wherein the regularizationFactor is transmitted from the DU to the RU in place of Section Type 6 of channel information based on the capability of the RU.

17. The DU of claim 13, wherein the regularizationFactor is related to a noise variance used in the MMSE calculation.

18. The section extension information includes information regarding a type of the section extension information associated with the regularization factor and information regarding a length of the section extension information, The DU of claim 13, wherein the regularizationFactor is 16 bits in length.

19. In a wireless communication system, a RU (radio unit) of a base station comprises: Transceiver a controller coupled to the transceiver unit, The controller: A control plane message is received via a fronthaul interface from a distributed unit (DU) using Section Type 5 for terminal scheduling information, the control plane message including section extension information; Identifying information indicating a regularization factor from the section extension information; The method is configured to obtain a beamforming weight based on the regularization factor; The regularizationFactor is an RU used for minimum mean square error (MMSE) calculation to generate multi-user (MU) beamforming weights for a UE on a slot-by-slot basis.

20. The RU described in claim 19, wherein Section Type 5 is defined in an O-RAN (open-radio access network).

21. The controller: The RU of claim 19, further configured to receive from the DU a management plane message indicating that the regularizationFactor has been sent in the section extension information.

22. The RU of claim 19, wherein the regularizationFactor is transmitted from the DU to the RU instead of Section Type 6 of channel information based on the capability of the RU.

23. The RU of claim 19, wherein the regularizationFactor is related to a noise variance used in the MMSE calculation.

24. The section extension information includes information regarding a type of the section extension information associated with the regularizationFactor and information regarding a length of the section extension information, 20. The RU of claim 19, wherein the regularizationFactor is 16 bits in length.

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