Apparatus and method for front-haul transmission in wireless communication systems

Abstract

To provide a fifth-Generation (5G) or pre-5G communication system for supporting higher data transfer rates after fourth-generation (4G) communication systems such as Long Term Evolution (LTE).SOLUTION: According to various embodiments, a device of a radio unit (RU) of a base station in a wireless communication system includes at least one transceiver and at least one processor that is coupled to the at least one transceiver. 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 acquire a beamforming weight based on the additional information. The first control message is configured to schedule a terminal in a control plane.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates in general to wireless communication systems, and more specifically to apparatus and methods for fronthaul transmission in wireless communication systems. [Background technology]

[0002] 4G (4 th Since the commercialization of communication systems, improved 5G (5 generation) has been developed to meet the increasing demand for wireless data traffic. th Efforts are being made to develop 5G or pre-5G communication systems. For this reason, 5G or pre-5G communication systems are also called Beyond 4G Network 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). To mitigate path loss and increase transmission distance in ultra-high frequency bands, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna technologies are being discussed for 5G communication systems.

[0004] Furthermore, in order to improve the system network, 5G communication systems are undergoing technological development, including advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation.

[0005] In addition, 5G systems have seen the development of 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 transmission capacity increases in wireless communication systems, function splitting is being applied to functionally separate base stations. Through function splitting, a base station can be separated into a DU (digital unit) and an RU (radio unit), a fronthaul is defined for communication between the DU and the RU, and transmission via the fronthaul is required. [Overview of the project] [Problems that the invention aims to solve]

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

[0008] Furthermore, this disclosure provides an apparatus and method for transmitting management messages on a front-haul interface in a wireless communication system.

[0009] Furthermore, this disclosure provides an apparatus and method for transmitting scheduling information and other information together on a front-haul interface in a wireless communication system.

[0010] Furthermore, this disclosure provides an apparatus and method for transmitting scheduling information and, in particular, regularization parameters together over a front-haul interface in a wireless communication system.

[0011] Furthermore, this disclosure provides an apparatus and method for reducing the memory burden on a digital unit (DU) and radio unit (RU) during operation of a radio unit (RU) in a wireless communication system by reducing the memory burden on the RU due to the storage of regularization parameters.

[0012] Furthermore, this disclosure provides a functional structure for RU for processing regularization parameters in wireless communication systems. [Means for solving the problem]

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

[0014] According to various embodiments of the present disclosure, the operation method of a radio unit (RU) of a base station in a wireless communication system includes the steps of 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 on the control plane.

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

[0016] According to various embodiments of the present disclosure, the equipment 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 with the at least one transceiver, the at least one processor configured to receive a first control message including a section extension field from a digital unit (DU) via a fronthaul interface, to identify additional information based on the section extension field, and to obtain a beamforming weight value based on the additional information, the first control message may be configured to schedule a terminal on a control plane. [Effects of the Invention]

[0017] Devices and methods according to various embodiments of the present disclosure enable efficient operation of the interfaces between a DU (digital unit) and a RU (radio unit) 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 those with ordinary knowledge in the technical field to which the present disclosure belongs from the following description.

Brief Description of Drawings

[0019] [Figure 1A] It is a diagram showing a wireless communication system according to various embodiments of the present disclosure. [Figure 1B] It is a diagram showing an example of a fronthaul structure by functional separation of a base station according to various embodiments of the present disclosure. [Figure 2] It is a diagram showing the configuration of a DU (digital unit) according to various embodiments of the present disclosure. [Figure 3] It is a diagram showing the configuration of a RU (radio unit) according to various embodiments of the present disclosure. [Figure 4] It is a diagram showing an example of function split according to various embodiments of the present disclosure. [Figure 5A] It is a diagram showing an example of a control message according to Section type 6. [Figure 5B] It is a diagram showing an example of the functional configuration of a RU for beamforming information processing. [Figure 5C] It is a diagram showing the relationship between a regularization factor and scheduling. [Figure 6] It is a diagram showing an example of an extension field according to various embodiments of the present disclosure. [Figure 7] It is a diagram showing an example of a management message for Section type 6 according to various embodiments of the present disclosure. [Figure 8A]This figure shows the operation flow of the DU for extended fields according to various embodiments of the present disclosure. [Figure 8B] This figure shows the operation flow of the RU for extended fields according to various embodiments of the present disclosure. [Figure 9A] This figure shows the operation flow of the DU for management messages for Section type 6 according to various embodiments of the present disclosure. [Figure 9B] This figure shows the operation flow of the RU for management messages for Section type 6 according to various embodiments of the present disclosure. [Figure 10] This figure shows examples of functional configurations of RUs for beamforming information processing according to various embodiments of the present disclosure. [Figure 11] This figure shows the relationship between the regularization factor and scheduling in various embodiments of this disclosure. [Figure 12] This figure shows examples of the relationship between DU and RU by section extension fields in various embodiments of the present disclosure. [Modes for carrying out the invention]

[0020] The terms used in this disclosure are used solely to describe specific embodiments and are not intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates a different meaning. Terms used herein, including technical or scientific terms, may have the same meaning as those generally understood by a person of ordinary skill in the art described herein. Terms used herein that are defined in a general dictionary may be interpreted as having the same or similar meaning as their meaning in the context of the relevant art and not as ideally or excessively formal unless explicitly defined herein. In some cases, terms defined herein may not be interpreted in a way that excludes embodiments of this disclosure.

[0021] The various embodiments of the Disclosure described below illustrate hardware-based approaches. However, since the various embodiments of the Disclosure include techniques that use both hardware and software, the various embodiments of the Disclosure do not exclude software-based approaches.

[0022] The following terms used in the explanation refer to signals (e.g., message, information, preamble, signal, signaling, sequence, stream), resources (e.g., symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), opportunity), operational states (e.g., step, operation, procedure), data (e.g., user stream, IQ data, information, bit, symbol, codeword), channels, control information (e.g., DCI (downlink control information), MAC CE (medium access control control element), RRC (radio resource control) signaling), and network entities (network). Terms referring to entities, components of devices, etc., are provided as examples for explanatory purposes only. Therefore, this disclosure is not limited to the terms described below, and other terms with equivalent technical meaning may be used.

[0023] Furthermore, while the expressions "greater than" or "less than" may be used in this disclosure to determine whether a particular condition is satisfied or fulfilled, this is merely an example and does not preclude the use of "greater than or equal to" or "less than or equal to." Conditions described as "greater than or equal to" may be replaced with "greater than," conditions described as "less than or equal to" may be replaced with "less than," and conditions described as "greater than or equal to and less than" may be replaced with "greater than and less than."

[0024] This disclosure uses terminology from certain communication standards (e.g., 3GPP (registered trademark, 3rd Generation Partnership Project), xRAN (extensible radio access network), O-RAN (open-radio access network)) to describe various embodiments, but these are merely illustrative examples. The various embodiments of this disclosure can be easily modified and applied to other communication systems.

[0025] Figure 1A illustrates a wireless communication system according to various embodiments of the present disclosure. Figure 1 illustrates a base station 110, terminal 120, and terminal 130 as part of a node utilizing a wireless channel in the wireless communication system. Although Figure 1 illustrates only one base station, other base stations identical or similar to base station 110 may be further included.

[0026] Base station 110 is network infrastructure that provides wireless connectivity to terminals 120 and 130. Base station 110 has coverage defined in a predetermined geographical area based on the distance over which it can transmit signals. In addition to base station, base station 110 can also be referred to as "access point (AP)", "eNodeB (eNB)", "5G node (5th generation node)", "next generation nodeB (gNB)", "wireless point", "transmission / reception point (TRP)", or other terms with equivalent technical meaning.

[0027] Terminals 120 and 130 are devices used by the user and communicate with base station 110 via a radio channel. The link from base station 110 to terminal 120 or terminal 130 is called a downlink (DL), and the link from terminal 120 or terminal 130 to base station 110 is called an uplink (UL). Terminals 120 and 130 can also communicate with each other via a radio channel. In this case, the link between terminals 120 and 130 (device-to-device link; D2D) is called a sidelink, and the sidelink may be used alternately with the PC5 interface. In some cases, at least one of terminals 120 and 130 can be operated without user involvement. That is, at least one of terminals 120 and 130 is a device that performs machine-type communication (MTC) and may not be carried by the user. Each of terminals 120 and 130 may be referred to as "terminal," "user equipment (UE)," "customer premises equipment (CPE)," "mobile station," "subscriber station," "remote terminal," "wireless terminal," "electronic device," or "user device," or any other term with equivalent technical meaning.

[0028] Base station 110, terminal 120, and terminal 130 are capable of beamforming. The base station 110, terminals 120, and terminals 130 can transmit and receive radio signals not only in relatively low frequency bands (e.g., FR1 (frequency range 1) of NR) but also in high frequency bands (e.g., FR2 of NR, millimeter wave (mmWave) bands (e.g., 28GHz, 30GHz, 38GHz, 60GHz)). In some embodiments, the base station can communicate with the terminals within the frequency range corresponding to FR1. In some embodiments, the base station can communicate with the terminals within the frequency range corresponding to FR2. In this case, to improve channel gain, the base station 110, terminals 120, and terminals 130 can perform beamforming. Here, beamforming can include transmit beamforming and receive beamforming. That is, the base station 110, terminals 120, and terminals 130 can give directivity to the transmitted or received signal. To this end, the base station 110 and terminals 120 and 130 perform beam search or beam management. The serving beams 112, 113, 121, and 131 can be selected by the management procedure. After serving beams 112, 113, 121, and 131 are selected, subsequent communication may be conducted by resources that have a quasi-co-located (QCL) relationship with the resource that sent serving beams 112, 113, 121, and 131.

[0029] The first and second antenna ports can be described as being in a QCL relationship if the large-scale characteristics of the channel that transmitted symbols on the first antenna port can be inferred from the channel that transmitted symbols on the second antenna port. For example, the large-scale characteristics may include at least one of the following: delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial receiver parameter.

[0030] Although Figure 1A illustrates that both the base station and the terminal perform beamforming, the various embodiments of this disclosure are not necessarily limited to this. In some embodiments, the terminal may or may not perform beamforming. Similarly, the base station may or may not perform beamforming. In other words, either the base station or the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

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

[0032] Although Figure 1A illustrates that both the base station and the terminal perform beamforming, the various embodiments of this disclosure are not necessarily limited to this. In some embodiments, the terminal may or may not perform beamforming. Similarly, the base station may or may not perform beamforming. In other words, either the base station or the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0033] Conventionally, in communication systems with relatively large base station cell radii, each base station was installed to include both a digital processing unit (DU) and an RF (radio frequency) processing unit (RU). However, 4G (4 th In the 2000 generation and / or subsequent communication systems, high frequency bands are used, resulting in smaller base station cell radii and an increased number of base stations required to cover a specific area, which in turn increases the installation costs for operators. To minimize base station installation costs, a structure has been proposed in which the base station's DU and RU are separated, with one or more RUs connected to a single DU via a wired network, and one or more RUs are geographically distributed to cover a specific area. Various embodiments of base station configurations and extensions of this disclosure are described below through Figure 1B.

[0034] Figure 1B shows examples of fronthaul structures with functional isolation of base stations according to various embodiments of this disclosure. Unlike backhaul, which is between the base station and the core network, fronthaul refers to the space between the wireless LAN and the base station.

[0035] Referring to Figure 1B, base station 110 can include DU160 and RU180. The fronthaul 170 between DU160 and RU180 is Fx It can be operated via an interface. For the operation of the fronthaul 170, interfaces such as eCPRI (enhanced common public radio interface) and ROE (radio over ethernet) may be used.

[0036] As communication technology advances, mobile data traffic increases, significantly raising the bandwidth requirements for the fronthaul between digital and radio units. In configurations like C-RAN (centralized / cloud radio access network), the DU (Digital Unit) can be implemented to perform functions related to the PDCP (packet data convergence protocol), RLC (radio link control), MAC (media access control), and PHY (physical) layers, while the RU (Radio Unit) can perform more functions related to the PHY layer in addition to RF (radio frequency) functions.

[0037] The DU160 can perform higher-layer functions of a wireless network. For example, the DU160 can perform MAC layer functions and parts of the PHY layer. Here, parts of the PHY layer refer to functions performed at a higher level of the PHY layer, and may include, for example, channel encoding (or channel decoding), scrambling (or descrambling), modulation (or demodulation), and layer mapping (or layer demapping). According to one embodiment, if the DU160 conforms to the O-RAN standard, it may be referred to as O-DU (O-RAN DU). The DU160 may, as necessary, be represented in place of a first network entity for a base station (e.g., gNB) in embodiments of this disclosure.

[0038] The RU180 can handle lower-layer functions of a wireless network. For example, the RU180 can perform some of the PHY layer functions, specifically RF functions. Here, "some of the PHY layer functions" refers to functions performed at a relatively lower level than the DU160, and may include, for example, IFFT conversion (or FFT conversion), CP insertion (CP rejection), and digital beamforming. Specific examples of such functional separation are described in detail in Figure 4. The RU180 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 with equivalent technical meaning. According to one embodiment, if the RU180 conforms to the O-RAN standard, it may be referred to as an O-RU (O-RAN RU). The RU180 may, as necessary, be used in place of a second network entity for a base station (e.g., gNB) in embodiments of this disclosure.

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

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

[0041] Figure 2 shows the configuration of a DU in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in Figure 2 can be understood as part of a base station, similar to the configuration of DU160 in Figure 1B. The terms "~unit," "~device," etc., used hereafter refer to a unit that processes at least one function or operation, which may be implemented in hardware, software, or a combination of hardware and software.

[0042] Referring to Figure 2, the DU160 includes a communication unit 210, a storage unit 220, and a control unit 230.

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

[0044] The communication unit 210 can also perform functions for sending and receiving signals in a wireless communication environment. For example, the communication unit 210 can perform conversion functions between baseband signals and bit sequences according to the system's physical layer specifications. For example, when transmitting data, the communication unit 210 generates complex symbols by encoding and modulating the transmitted bit sequence. When receiving data, the communication unit 210 restores the received bit sequence by demodulating and decoding the baseband signal. The communication unit 210 can also include a number of transmission and reception paths. Furthermore, according to one embodiment, the communication unit 210 may be connected to a core network or to other nodes (e.g., an IAB (integrated access backhaul)).

[0045] The communication unit 210 can transmit and receive signals. For this purpose, the communication unit 210 may include at least one transceiver. For example, the communication unit 210 can transmit synchronization signals, reference signals, system information, messages, control messages, streams, control information, or data. The communication unit 210 can also 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 the "transmitting unit," the "receiving unit," or the "transmitting / receiving unit." In the following explanation, transmission and reception performed via the wireless channel are used to mean that the communication unit 210 performs the processing described above.

[0047] Although not shown in Figure 2, the communication unit 210 may further include a backhaul communication unit for connecting to the core network or other base stations. The backhaul communication unit provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit converts bit streams transmitted from the base station to other nodes, such as other connecting nodes, other base stations, higher-level nodes, and the core network, into physical signals, and converts physical signals received from other nodes into bit streams.

[0048] The storage unit 220 stores data such as the basic program for the operation of the DU160, application programs, and configuration information. The storage unit 220 may include memory. The storage unit 220 may consist of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. The storage unit 220 then provides the stored data in response to requests from the control unit 230.

[0049] The control unit 230 controls the overall operation of the DU160. For example, the control unit 230 transmits and receives signals via the communication unit 210 (or via the backhaul communication unit). The control unit 230 also records and reads data from the storage unit 220. Furthermore, the control unit 230 can perform the functions of the protocol stack required by the communication standard. To this end, the control unit 230 may include at least one processor. In some embodiments, the control unit 230 may include a control message generation unit that generates control plane messages with an extended field containing a regularization factor, and a management message generation unit that generates management messages to deactivate the regularization factor field of existing messages containing a regularization factor (e.g., O-RAN Section Type 6 control plane messages). The control message generation unit and the management message generation unit are instruction sets or codes stored in the storage unit 230, and may be at least temporarily resided instructions / codes or a storage space for storing instructions / codes in the control unit 230, or they may be part of the circuitry that constitutes the control unit 230. According to various embodiments, the control unit 230 can control the DU160 to perform the operations according to various embodiments described later.

[0050] The configuration of DU160 shown in Figure 2 is merely an example, and the configuration shown in Figure 2 does not limit the examples of DUs that perform various embodiments of this disclosure. In other words, some configurations may be added, deleted, or modified according to various embodiments.

[0051] Figure 3 shows the configuration of a RU in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in Figure 3 can be understood as part of a base station, similar to the configuration of RU180 in Figure 1B. The terms "~unit," "~device," etc., used herein refer to a unit that processes at least one function or operation, which may be implemented in hardware, software, or a combination of hardware and software.

[0052] Referring to Figure 3, RU180 includes a communication unit 310, a storage unit 320, and a control unit 330.

[0053] The communication unit 310 performs functions for transmitting and receiving signals via a wireless channel. For example, the communication unit 310 upconverts a baseband signal to an RF band signal and transmits it via an antenna, and downconverts the RF band signal received via the antenna back to a baseband signal. For example, the communication unit 310 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and so on.

[0054] Furthermore, the communication unit 310 can include a number of transmit and receive paths. Moreover, the communication unit 310 can include an antenna unit. The communication unit 310 can include at least one antenna array composed of a number of antenna elements. From a hardware standpoint, the communication unit 310 can consist of digital and analog circuits (e.g., an RFIC (radio frequency integrated circuit)). Here, the digital and analog circuits can be implemented in a single package. The communication unit 310 can also include a number of RF chains. The communication unit 310 can perform beamforming. The communication unit 310 can apply a beamforming weight to a signal to give the signal to be transmitted or received a directivity setting in the control unit 330. According to one embodiment, the communication unit 310 can include an RF (radio frequency) block (or RF unit).

[0055] The communication unit 310 can transmit and receive signals. For this purpose, the communication unit 310 may include at least one transceiver. The communication unit 310 can transmit downlink signals. Downlink signals may include synchronization signals (SS), reference signals (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)), configuration messages, control information, or downlink data. The communication unit 310 can also receive uplink signals. Uplink signals may include random access-related signals (e.g., random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), reference signals (e.g., SRS (sounding reference signal), DM-RS), or power headroom reports (PHR).

[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 the "transmitting unit," the "receiving unit," or the "transmitting / receiving unit." In the following explanation, transmission and reception performed via the wireless channel are used to mean that the communication unit 310 performs the processing described above.

[0057] The storage unit 320 stores data such as the basic program for the operation of the RU180, application programs, and configuration information. The storage unit 320 may consist of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. The storage unit 320 then provides the stored data in response to requests from the control unit 330. According to one 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 control unit 330 controls the overall operation of the RU180. For example, the control unit 330 transmits and receives signals via the communication unit 310. The control unit 330 also records and reads data from the storage unit 320. Furthermore, the control unit 330 can perform the functions of the protocol stack required by the communication standard. To this end, the control unit 330 may include at least one processor. In some embodiments, the control unit 230 may include a control message interpreter for interpreting control plane (C-plane) messages that have an extended field containing a regularization factor, and a management message interpreter for interpreting management plane (M-plane) messages to deactivate the regularization factor field of messages that contain an existing regularization factor (e.g., Control plane messages of Section type 6 in O-RAN). The control message interpretation unit and the management message interpretation unit are instruction sets or codes stored in the storage unit 320, and may be at least temporarily resided instructions / codes or storage spaces for storing instructions / codes in the control unit 330, or they may be part of the circuitry that constitutes the control unit 330. The control unit 330 may include various modules for communication. According to various embodiments, the control unit 330 can control the terminal to perform operations according to various embodiments described later.

[0059] Figure 4 shows examples of function splitting in wireless communication systems according to various embodiments of this disclosure. As wireless communication technology develops (e.g., 5G (5 th With the introduction of 5G communication systems (or NR (new radio) communication systems), the number of RUs required for installation has increased further due to the increased frequency bandwidth and the extremely small cell radius of base stations. In addition, with 5G communication systems, the amount of data transmitted has increased more than tenfold, and the transmission capacity of the wired network transmitted in the fronthaul has increased significantly. Due to these factors, the installation cost of wired networks in 5G communication systems can increase very significantly. Therefore, in order to reduce the transmission capacity of the wired network and lower the installation cost of the wired network, a technology has been proposed that reduces the transmission capacity of the fronthaul by transferring some functions of the DU's modem to the RU, and such a technology can be called "function split".

[0060] To reduce the burden on the DU, a method is considered to extend the role of the RU, which is currently only responsible for RF functions, to include some physical layer functions. In this case, the higher the layer functions the RU performs, the greater the processing load of the RU, which increases the transmission bandwidth in the fronthaul, and at the same time, the constraints on delay time requirements due to response processing may decrease. On the other hand, the higher the layer functions the RU performs, the less virtualization gain there is, and the larger / heavy / cost of the RU increases. Considering the trade-offs of the above advantages and disadvantages, it is necessary to implement the optimal functional separation.

[0061] Referring to Figure 4, the functional separation at the physical layers below the MAC layer is illustrated. In the case of downlink (DL), which transmits signals to terminals over a wireless network, the base station can sequentially perform channel encoding / scrambling, modulation, layer mapping, antenna mapping, RE mapping, digital beamforming (e.g., precoding), IFFT conversion / CP insertion, and RF conversion. In the case of uplink (UL), which receives signals from terminals over a wireless network, the base station can sequentially perform RF conversion, FFT conversion / CP rejection, digital beamforming (pre-combining), RE demapping, channel estimation, layer demapping, demodulation, and decoding / discrambling. The separation of uplink and downlink functions can be defined in various types depending on the trade-offs described above, the needs between vendors, and the discussions in standards.

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

[0063] According to one embodiment, when large-capacity signal processing is expected, such as in the FR1 MMU, functional isolation at a relatively high layer (e.g., fourth functional isolation 420b) may be required to reduce fronthaul capacitance. On the other hand, functional isolation at an excessively high layer (e.g., sixth functional isolation 430) can complicate the control interface and include a large number of PHY processing blocks within the RU, potentially burdening the implementation of the RU. Therefore, appropriate functional isolation may be required depending on the arrangement and implementation method of the DU and RU.

[0064] According to one embodiment, if the precoding of data received from the DU cannot be processed (i.e., the RU's precoding capability is limited), a third functional isolation 420a or lower (e.g., a second functional isolation 410) may be applied. Conversely, if the RU has the capability to process the precoding of data received from the DU, a fourth functional isolation 420b or higher (e.g., a sixth functional isolation 430) may be applied. Hereafter, the various embodiments described in this disclosure will be based on the third functional isolation 420a or fourth functional isolation 420b for beamforming processing in the RU, unless otherwise specified, but this does not preclude the configuration of embodiments using other functional isolations. The control plane messages, management plane messages, or configuration / operation flow of other devices shown in Figures 5A to 11 below may be applied not only to the third functional isolation 420a or fourth functional isolation 420b but also to other functional isolations.

[0065] Various embodiments of this disclosure exemplify the use of eCPRI and O-RAN standards as fronthaul interfaces during message transmission between a DU (e.g., DU160 in Figure 1B) and an RU (e.g., RU180 in Figure 1B). The Ethernet payload of a message may include an eCPRI header, an O-RAN header, and additional fields. Hereafter, various embodiments of this disclosure will be described using eCPRI or O-RAN standard terminology, although other expressions with equivalent meanings may be used in place of these various embodiments.

[0066] The fronthaul transport protocol can be Ethernet or eCPRI, which are easily shared across the network. The Ethernet payload may include an eCPRI header and an O-RAN header. 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, and z can be configured by the management plane (M-plane). This field can indicate the transmission path of control messages (eAxC (extended Antenna-carrier) in eCPRI) in various embodiments during multi-layer transmission.

[0068] CU_Port_ID (x bits): Identifies channel cards. Can include modems (2 bits for channel card, 2 bits for modem). BandSector_ID(y bits): Distributed by Cell / Sector CC_ID (z bits): Distinguished by Component carrier RU_Port_ID(w bits): Distinguished by layer, T, antenna, etc. ecpriSeqid (2 bytes): Sequence IDs are managed separately for ecpriRtcid / ecpriPcid, and both Sequence IDs and subsequence IDs are managed separately. Radio-transport-level fragmentation is possible using the subsequence ID (this differs from application-level fragmentation). The fronthaul application protocol may include the control plane (C-plane), user plane (U-plane), synchronization plane (S-plane), and management plane (M-plane).

[0069] The control plane may be configured to provide scheduling and beamforming information via control messages. The user plane may include user downlink data (IQ data or SSB / RS), uplink data (IQ data or SRS / RS), or PRACH data. The weighted vector of the beamforming information described above may be multiplied by the user 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 reporting. Section Types are defined to define the types of messages transmitted on the control plane. A Section Type can indicate the purpose of a control message transmitted on the control plane. For example, the purposes of different Section Types are as follows:

[0070] sectionType=0:DL idle / guard periods - Tx blanking application for power saving sectionType=1: Mapping BF index or weight (O-RAN mandatory BF method) to the RE of DL / UL channels sectionType=2:reserved sectionType=3: Mapping beamforming index or weight to RE of PRACH and mixed-numerology channels sectionType=4:reserved sectionType=5: Transmit UE scheduling information to enable RU to perform real-time BF weight calculation (O-RAN optional BF method) sectionType=6: Periodically transmit 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 a RU communicates with a UE via beamforming, the RU requires information about the current channel and scheduling information. Specifically, the RU is required to obtain Section Type 5 control messages and Section Type 6 control messages. From the Section Type 5 control messages, the RU can identify whether the UE has slot-specific scheduling, and from the Section Type 6 control messages, it can identify information about the current channel state. Section Type 6 control messages may be transmitted periodically. Channel information may also be transmitted periodically so that the RU can calculate the beamforming weights for each slot. An example of a Section Type 6 control message is shown below through Figure 5A.

[0072] Figure 5A shows an example of a control message using Section type 6. A control message using Section type 6 is configured for the purpose of carrying channel information.

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

[0074] Common header 503 is a common radio application header and may contain the following parameters:

[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 the first UE, and the second section information for the second UE. The following description will be based on the first section information 505, but the same or similar format may also apply to the second section information 507. The first section information 505 may include parameters such as those listed below.

[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 Section Type 6 control message that is transmitted periodically. 'regularizationFactor' can provide a signaled value to support MMSE (minimum mean square error) operation in the RU when beamforming weighting is supported (e.g., UL for Option 7-2x Category A (e.g., third functional isolation 420a in Figure 4) or DL / UL for Option 7-2x Category B (e.g., fourth functional isolation 420b in Figure 4). 'regularizationFactor' represents the above value in 2 bytes (i.e., 16 bits).

[0079] According to various embodiments of this disclosure, the regularization parameter represented by 'regularizationFactor' can be used to derive beamforming weights. For example, the relationship between the regularization parameter and beamforming weights can be derived based on the following equation.

number

number

number

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

number

[0081] Hereafter, this disclosure describes message, signaling, DU / RU apparatus and methods for the 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. Furthermore, while embodiments of this disclosure describe the regularization parameter as a 2-byte value of 'regularizationFactor' in Section Type 6 as an example, it may also be understood that the data size / calculation method may be modified to a form easily accessible to the average engineer (e.g., 3-byte), as one embodiment of this disclosure.

[0082] FIG. 5B shows an example of the functional configuration of the 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 updated periodically. For example, the channel information can include 'ciIsample(Ci)' or 'ciQsample(Cq)' of Section Type 6, or a value obtained therefrom. Ci represents the I value of the complex channel information, and Cq represents the Q value of the complex channel information. The regularization factor memory 523 can obtain information on the regularization parameter from a control message of Section Type 6. The regularization parameter is transmitted (updated) together when the channel information is transmitted (updated) to the C-plane Section Type 6. The RU can store the information on the regularization parameter in the regularization factor memory 523. At this time, the information on the regularization parameter can be updated periodically. For example, the information on the regularization parameter can include'regularization factor' of Section Type 6, or a value obtained therefrom. The regularization factor memory 523 can be referred to as an R nn memory (e.g., R nn is the regularization parameter value of Equation 2).

[0084] Section Type 5 control messages contain scheduling information for the UE. Scheduling can be performed in specified units (e.g., slot units). Scheduling information can be iteratively provided to the regularization factor memory 523 for each slot. Since information for regularization parameters is transmitted along with channel information, the RU can have a regularization factor memory 523 of the same dimensions as the channel memory 521, which is the memory that stores the channel information. The RU can obtain the corresponding channel value and regularization parameter value from the respective memory based on the scheduling information transmitted for each slot (e.g., Section Type 5 control messages) and calculate the beamforming weight. Specifically, in order to calculate the beamforming weight, the RU can obtain channel information from the channel memory 521 and regularization parameters from the regularization factor memory 523. Based on the regularization parameters and channel information, the RU can calculate and obtain the beamforming weight (or MU (multi-user) weight) for the current channel for MMSE (or ZFBF).

[0085] At this time, although the beamforming weighting value only needs to be calculated 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 UE is scheduled. When a terminal is actually scheduled, the most recently transmitted regularization parameter value must be used, so the regularization factor memory 523 needs to store all transmitted regularization parameter values ​​even if they are not actually used. Therefore, the information for regularization parameters that is iteratively stored even when the UE is not actually scheduled places a burden on the regularization factor memory 523. Moreover, if the channel information is updated at a relatively long period compared to the scheduling information which is updated every slot (e.g., 0.5 ms), the probability that the regularization parameters of Section Type 6 will not correctly reflect the channels actually experienced by the terminal increases. A specific example is shown in Figure 5C.

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

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

[0088] When UE #3 is scheduled at the front end 551, a relatively short time has elapsed since the Section Type 6 channel information was updated, allowing the RU to derive a beamforming weight that more closely matches the actual channel. However, when UE #3 is scheduled at the rear end 553, a relatively long time has elapsed since the Section Type 6 channel information was updated, making it difficult for the RU to derive a beamforming weight that more closely matches the actual channel. This is because the channel changes over time, resulting in a difference between the actual channel and the channel information transmitted via the DU. This problem leads to larger errors as the transmission period of Section Type 6 control messages lengthens, and such errors cause inaccurate beamforming weights to be generated, leading to a decrease in transmission performance.

[0089] Hereafter, various embodiments of this disclosure describe methods for transmitting regularization parameters along with scheduling information, instead of periodically transmitting the regularization parameters, in order to address the problems described through Figures 5A to 5C. Furthermore, various embodiments of this disclosure describe methods for handling periodically transmitted 'regularizationFactor' of Section Type 6 as defined in existing O-RAN standards, in order to satisfy backward compatibility. Furthermore, various embodiments of this disclosure describe new functional implementation methods for RUs to avoid memory burden in storing periodically transmitted information.

[0090] Furthermore, this disclosure may be understood to include not only the transmission of scheduling / channel information for 5G communication systems (e.g., NR), but also implementation for 4G communication systems (e.g., LTE) as embodiments of this disclosure. In other words, the communication systems for which the DU and RU operations described below are provided are not limited to 5G communication systems, nor are they limited to 4G communication systems.

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

[0092] Referring to Figure 6, the section extension field 600 in various embodiments can contain information for regularization parameters. The regularization parameters may be values ​​corresponding to 'regularizationFactor' in Section Type 6. -extType can indicate the type of additional parameter. In one embodiment, if extType indicates 11, extType may indicate that the additional parameter includes a value for the regularization factor for MMSE (or ZFBF). The value '11' is illustrative, and of course other numbers may be assigned to specify the type of parameter.

[0093] The -ef option can indicate the presence or absence of an additional section extension field. A value of '1' for ef indicates that an additional section extension field exists, while a value of '0' for ef indicates that an additional section extension field does not exist.

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

[0095] Section extension fields containing regularization parameters in various embodiments can be attached to and transmitted together with control messages containing scheduling information (e.g., O-RAN Section Type 5 control plane messages). By having the DU transmit regularization parameters along with scheduling information, the problem of not being able to reflect the actual channel state when calculating beamforming weights due to the difference between the scheduling time and the transmission time of the regularization parameters can be resolved.

[0096] Although not shown in Figure 6, a section extension field containing channel information may be defined. For example, a section extension field containing channel information (e.g., ciIsample, ciQsample) may be defined within a Section Type 6 control message. The channel information within the section extension field may be organized by antenna and frequency resource (e.g., PRB, PRB group, BWP (bandwidth part), etc.). By considering the capability and / or rank information of the terminal that the RU intends to service, the DU can obtain the required number of antennas from the total antennas. Furthermore, the DU can identify the frequency range that will actually be served to the terminal from the resources of the total frequency range, considering cases where a relatively small amount of channel information is required depending on the type of communication method (e.g., LTE), or by considering the scheduling area for a particular terminal.

[0097] In some embodiments, channel information can include channel information for each of the overall antennas and each of the overall PRBs. In other embodiments, channel information can include channel information for each of some of the antennas in the overall antenna and each of some of the PRBs in the overall PRBs. In yet another embodiment, channel information can include channel information for each of some of the antennas in the overall antenna and each of the overall PRBs. In yet another embodiment, channel information can include channel information for each of the overall antennas and each of some of the PRBs. According to one embodiment, channel information can be configured as a section extension field by transmitting channel information to the actual scheduling area of ​​the terminal, thereby reducing the amount of channel information required.

[0098] Instead of being transmitted periodically as in Section Type 6, channel information can be transmitted to the RU in the form of a section extension field, attached to Section Type 5 where scheduling information is transmitted. Similar to regularization parameters, by providing it at the time of the terminal's actual scheduling, the problem of degraded communication performance due to the difference between the time of channel information transmission and the actual scheduling time can be eliminated. Furthermore, if accurate channel information is needed irregularly as needed, the section extension field allows the RU to obtain the optimal beamforming weighting value.

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

[0100] Furthermore, according to one embodiment, a section extension field containing channel information may be configured as shown in the table below. The section extension field containing channel information may also contain information for 'regularizationFactor', i.e., the regularization parameter. A section extension field containing both channel information and regularization parameter information may be attached to and transmitted with a control message containing terminal (UE) scheduling information (e.g., a Section Type 5 control message for a C-plane). [Table 2]

[0101] In Tables 1 and 2, channel information is illustrated with ciIsample and ciQsample for one antenna / one PRB, but the diverse embodiments of this 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 of ciIsample and ciQsample is variable and can be set by the M-plane.

[0102] On the other hand, even if regularization parameters are transmitted along with scheduling information via section extension fields, regularization parameters transmitted by Section Type 6 control messages of existing standards (e.g., O-RAN 2.00) are periodically transmitted to the RU. Because the RU's memory is periodically transmitted regularization parameters, Section Type 6 control messages remain a burden. The following various embodiments of this disclosure propose methods to satisfy backward compatibility with existing standards and to reduce the impact of the 'regularizationFactor' in Section Type 6 control messages.

[0103] Figure 7 shows examples of management messages for Section type 6 according to various embodiments of this disclosure. Management messages refer to messages transmitted in the O-RAN management plane (M-plane). DUs can communicate with RUs via packet in the management area within the main card. Management messages can be transmitted from DU to RU or from RU to DU. The management plane can perform initial installation ("start up"), software management, configuration management, performance management, fault management, and file management.

[0104] Referring to Figure 7, the DU can generate a management message. In various embodiments, the management message may be a message to set the 'regularization factor' of the Section Type 6 control message to invalid in the RU. In some embodiments, the management message may include a parameter (hereinafter referred to as the selection parameter) that indicates the selection of the transmission medium. The selection parameter can indicate whether to transmit the regularization parameter by a Section Type 6 message in the control plane, as has been done, or by a section extension field. For example, a value of '0' for the selection parameter can indicate transmission of the regularization parameter by a Section Type 6 message. A value of '1' for the selection parameter can indicate transmission of the regularization parameter by a section extension field. In this case, if the value of the selection parameter indicates transmission of the regularization parameter by a section extension field, the regularizationFactor value in the Section Type 6 control message is invalid. An RU that receives a management message containing the above selection parameter value does not need to consider the regularizationFactor value of Section Type 6. For example, a RU can ignore or discard the regularizationFactor value of a Section Type 6 that is transmitted periodically. Also, for example, a RU does not need to consider the regularizationFactor value for a specified period of time.

[0105] The DU can transmit management messages to the RU. From these management messages, the RU can identify how to obtain regularization parameters. For example, the RU can obtain regularization parameters from section extension fields. Another example is that the RU can obtain regularization parameters from Section Type 6.

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

[0107] In various embodiments, when it is difficult to transmit messages that periodically transmit channel information (e.g., control messages of Section Type 6) (e.g., when the memory allocation of the RU is excessively large or the capacity of the RU is insufficient), or when the transmission capacity of the fronthaul is sufficiently large, the DU can transmit additional information along with scheduling information via section extension fields. In this case, the additional information may include information that replaces the information in the control messages of Section Type 6. For example, the additional information may include channel information. Also, for example, the additional information may include information for regularization parameters. By transmitting additional information via section extension fields, the DU can substitute Section Type 6 with Section Type 5 control messages.

[0108] Figure 8A illustrates the operation flow of a DU for an extended field according to various embodiments of the present disclosure. The DU is exemplified by DU160 in Figure 2.

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

[0110] In operation 803, the DU can transmit a control message for scheduling to the RU, which includes a section extension field. The DU can construct a control message for scheduling; that is, the DU can generate a message that includes the UE's scheduling information in a C-plane control message. For example, the DU can generate a Section Type 5 control message. The DU can attach an extension section field to the control message, which may be a section extension field set in operation 801. The DU can transmit the control message to the RU via the fronthaul interface; that is, the scheduling control message can transmit both scheduling information for the terminal and regularization parameters for the channel to the RU.

[0111] Figure 8B illustrates the operation flow of the RU for an extended field according to various embodiments of the present disclosure. The RU is exemplified by RU180 in Figure 2.

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

[0113] In operation 853, the RU can identify regularization parameters from section extension fields in the control message. The RU can identify section extension fields in the control message. The RU can determine what information is contained within a section extension field from its type information (e.g., extType). The RU can determine from the specified type value that a section extension field contains regularization parameters. The RU can identify regularization parameters. For example, regularization parameters may be represented by a 2-byte value.

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

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

[0116] Figures 8A and 8B describe a method to improve transmission performance by reducing errors due to differences in the timing of channel information acquisition by transmitting regularization parameters included in existing Section Type 6 by adding an extended field to a control message containing channel information. However, transmitting regularization parameters by extended section fields without separate processing for Section Type 6 regularization parameters results in a problem of excessively large (bulky) workload in the RU's memory. Specifically, since Section Type 6 is transmitted periodically, while scheduling is performed in units much shorter than the above period, in order to calculate beamforming weights that reflect real-time channel information, it becomes necessary to store channel information (e.g., channel information, regularization parameters) for each scheduling unit during the period. Therefore, a method for deactivating (or invalidating) the regularization parameters of existing Section Type 6 control messages that are transmitted periodically is described.

[0117] Figure 9A shows 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 DU160 in Figure 2.

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

[0119] Alternatively, in some embodiments, the management message may include information regarding the validity of the regularization parameter in 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 propagated by a 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 of an extended section field. For example, the management message may indicate the validity of 'regularizationFactor' in an extended section field with 1 bit. A value of '1' may indicate that the regularization parameter in the extended 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 extended field is valid. Alternatively, for example, the management message may include information regarding the validity period of the regularization parameter of an extended section field. The regularization parameter of the Section type 6 control message may be set to default, and the regularization parameter of the extended section field may be provided to the RU as needed. In this case, only the regularization parameter of the extended section field may be received during the validity period of the management message, and the regularization parameter of the Section Type 6 control message may be ignored or discarded.

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

[0122] By using management messages to instruct the RU on the validity of regularization parameters for a channel, the DU can efficiently process the regularization parameters even if the DU transmits management messages as in existing standards. In other words, backward compatibility can be satisfied.

[0123] Figure 9B illustrates the operation flow of the RU for a management message for Section type 6 according to various embodiments of the present disclosure. The RU is exemplified by RU180 in Figure 2.

[0124] Referring to Figure 9B, in operation 951, the RU can receive a management message for the regularization parameter. The RU can receive the management message from the DU via the fronthaul interface. The management message is a message transmitted on the M-plane and may be transmitted on the DU's main card. The management message for the regularization parameter may include information about the transmission method of 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. Also in some embodiments, the management message may include information about the validity of the regularization parameter of Section Type 6. Also in some embodiments, the management message may include information about the validity of the regularization parameter transmitted by a section extension field.

[0125] In operation 953, the RU can identify the method of transmitting regularization parameters. The RU can identify the method of transmitting regularization parameters based on the management messages received from the DU. For example, the RU may obtain regularization parameters only by control messages for channel information (e.g., control messages for Section Type 6). Alternatively, for example, the RU may obtain regularization parameters only by section extension fields. Alternatively, for example, the RU may obtain regularization parameters by at least one of either section extension fields or control messages for channel information.

[0126] In operation 955, the RU can receive a control message for channel information, including regularization parameters. The RU can receive the above control message from the DU via the fronthaul interface. The RU can determine whether the acquisition of regularization parameters is permitted by the control message for channel information. If the acquisition of regularization parameters is permitted by the control message for channel information, the RU can acquire the regularization parameters from the above control message (e.g., a control message for Section Type 6). The RU can determine the beamforming weight value based on the obtained regularization parameters.

[0127] If the acquisition of regularization parameters is not permitted by the control message for channel information, the RU can ignore or discard the regularization parameters 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, it can acquire regularization parameters from the extended fields in the control message containing the scheduling information. The RU can determine beamforming weights based on the acquired regularization parameters.

[0128] Although not shown in Figures 9A and 9B, control messages may be used in addition to management messages to indicate the method of transmitting regularization parameters. Management messages may be transmitted to the RU from the DU's main card, while control messages may be transmitted to the RU from the DU's channel card. Control messages may be transmitted in real time relative to management messages. According to one embodiment, certain fields or certain values ​​of 'regularizationFactor' in a Section Type 6 control message may indicate that 'regularizationFactor' in that control message is not valid.

[0129] Figure 10 shows 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 Figure 10, the channel memory 1021 can obtain channel information from the control message of Section Type 6. The RU can store the channel information in the channel memory 1021. The channel information may be updated periodically. For example, the channel information may include 'ciIsample(Ci)' or 'ciQsample(Cq)' of Section Type 6, or values ​​obtained therefrom. Ci represents the I value of the complex channel information, and Cq represents the Q value of the complex channel information. In this case, the RU can ignore or discard information regarding 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 one 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 the management message of the management plane from the DU. Also, according to one embodiment, the RU can identify that the regularization parameter in the control message of Section Type 6 is invalid based on the control message of the DU.

[0131] The RU can transmit Section Type 5 scheduling information to the channel memory 1021. The channel memory 1021 stores scheduling information on a slot-by-slot basis (scheduling-by-slot basis), and the results of this channel information can be used when calculating beamforming weights. The channel memory 1021 also outputs channel information on a slot-by-slot basis, and the output results can be used when calculating beamforming weights.

[0132] The RU can obtain regularization parameters from the section extension field transmitted with Section Type 5. Unlike the one shown in Figure 5B, various embodiments of the RU do not need to 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 parameters from the section extension field. Therefore, since the RU obtains the regularization parameters from the section extension field in the control message containing scheduling information, i.e., the Section Type 5 control message, the obtained regularization parameters can be immediately used to calculate the beamforming weight. This is because it is expected that the beamforming weight will be determined immediately as the terminal is scheduled in the corresponding slot.

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

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

[0135] Figure 11 shows the relationship between the regularization factor and scheduling in various embodiments of this disclosure.

[0136] Referring to Figure 11, the upward arrow indicates that the 'regularization factor' of the Section Type 5 control message for UE #3 is transmitted. Unlike what is shown in Figure 5C, the effective 'regularization factor' is not transmitted periodically, but rather can be transmitted by the scheduling time of UE #3. Since the regularization factor is updated immediately before UE #3 is scheduled, the RU can derive a beamforming weight that better matches the actual channel. Therefore, the RU can obtain the optimal beamforming weight regardless of whether it is located at the front end 551 or the rear end 553 within the scheduling period, as shown in Figure 5C.

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

[0138] Figure 12 shows examples of the relationship between DU and RU by section extension fields in various embodiments of the present disclosure. Section extension fields in various embodiments of the present disclosure may be configured to replace Section Type 6 control messages. In some embodiments, section extension fields may include information for regularization parameters. In some embodiments, section extension fields may include channel information.

[0139] Referring to Figure 12, a DU can be connected to multiple RUs. In this case, the RUs can be referred to as O-RUs according to the O-RAN standard. A DU can be connected to X O-RUs. A DU can be connected to O-RU #0, O-RU #1, O-RU #2, ..., up to O-RU #X-1. According to one embodiment, some of the O-RUs can periodically acquire channel information via Section Type 6. On the other hand, some of the O-RUs can acquire channel information via section extension fields according to various embodiments. The transmission method for each O-RU (e.g., the transmission method for regularization parameters), i.e., whether it is Section Type 6 or a section extension field, can be determined according to one embodiment by a parameter of the management plane (M-plane). The parameter of the management plane can select whether to transmit information associated with the channel by Section Type 6 (e.g., regularization parameters) or by a section extension field containing arbitrary additional information. The DU can set this for each RU by the parameter of the management plane.

[0140] The methods according to the embodiments described in the claims or specification of this disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0141] When implemented in software, a computer-readable storage medium may be provided to store one or more programs (software modules). The one or more programs stored on 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 perform the methods according to the embodiments described in the claims or specification of this disclosure.

[0142] Such programs (software modules, software) can be stored in random access memory, non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disc storage devices, compact disc-ROMs (CD-ROMs), digital versatile discs (DVDs), or other forms of optical storage devices, magnetic cassettes, or in memory composed of some or all of these. Furthermore, each constituent memory may contain multiple instances.

[0143] Furthermore, the program may be stored in an attachable storage device that can be accessed through a communication network such as the Internet, intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a combination thereof. Such a storage device can access the device performing the embodiments of the disclosure through an external port. Alternatively, a separate storage device on the communication network can access the device performing the embodiments of the disclosure.

[0144] In the specific embodiments of the Disclosure described above, the components included in the Disclosure are expressed singly or plurally in the specific embodiments presented. However, the singly or plural expressions are selected to suit the context presented for the convenience of explanation, and the Disclosure is not limited to singly or plural components; a plural component may consist of singular components, and a singly component may consist of plural components.

[0145] On the other hand, while specific embodiments have been described in the detailed description of this disclosure, it goes without saying that various modifications are possible within the limits that do not deviate from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the embodiments described, but should be defined not only by the claims described below, but also by equivalent claims. [Explanation of Symbols]

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

Claims

1. A method performed by a distributed unit (DU) of a base station in a wireless communication system, The process includes sending a management plane message to the RU (radio unit) to set the regularizationFactor in Section Type 5 regarding user equipment (UE) scheduling information, The aforementioned `regularizationFactor` is a method used in MMSE (minimum mean square error) calculations to generate multi-user (MU) beamforming weights for terminals on a per-slot basis.

2. The method according to claim 1, wherein the management plane message is transmitted based on the capability of the RU.

3. The aforementioned method, A step of generating a control plane message of Section Type 5 relating to the terminal scheduling information, wherein the control plane includes section extension information, The step of sending the control plane message to the RU further includes: The method according to claim 1, wherein the section extension information indicates the regularizationFactor.

4. Section Type 5 is defined in O-RAN (open-radio access network), The regularizationFactor is transmitted from the DU to the RU, based on the capabilities of the RU, instead of Section Type 6 of the channel information, and The method according to claim 1, wherein the regularization factor relates to the noise variance used in the calculation of the MMSE.

5. The section extension information includes information about the type of section extension information and information about the length of the section extension information, The type of the section extension information relates to the regularizationFactor, and The method according to claim 3, wherein the length of the regularizationFactor is 16 bits.

6. A method performed by a radio unit (RU) of a base station in a wireless communication system, The process includes receiving a management plane message from a distributed unit (DU) that sets the regularizationFactor in Section Type 5 relating to user equipment (UE) scheduling information, The aforementioned `regularizationFactor` is a method used in MMSE (minimum mean square error) calculations to generate multi-user (MU) beamforming weights for terminals on a per-slot basis.

7. The method according to claim 6, wherein the management plane message is received based on the capability of the RU.

8. The aforementioned method, The step of receiving a Section Type 5 control plane message relating to the terminal scheduling information from the DU, wherein the control plane message includes section extension information, The steps include identifying the section extension information indicating the regularization factor, and The method according to claim 6, further comprising the step of obtaining a beamforming weight value based on the regularization factor.

9. Section Type 5 is defined in O-RAN (open-radio access network), The regularizationFactor is transmitted from the DU to the RU, based on the capabilities of the RU, instead of Section Type 6 relating to channel information, and The method according to claim 6, wherein the regularization factor relates to the noise variance used in the calculation of the MMSE.

10. The section extension information includes information about the type of section extension information and information about the length of the section extension information, The type of the section extension information relates to the regularizationFactor, and The method according to claim 8, wherein the length of the regularizationFactor is 16 bits.

11. In wireless communication systems, a base station's DU (distributed unit) is: Transceiver, It includes a controller coupled to the aforementioned transmitting and receiving unit, The aforementioned controller, The RU (radio unit) is configured to send management plane messages to set the regularizationFactor in Section Type 5 regarding terminal (user equipment, UE) scheduling information, and The aforementioned regularizationFactor is a DU used in MMSE (minimum mean square error) calculations to generate multi-user (MU) beamforming weights for terminals on a per-slot basis.

12. The DU according to claim 11, wherein the management plane message is transmitted based on the capability of the RU.

13. The aforementioned controller, A control plane message of Section Type 5 relating to the terminal scheduling information is generated, and the control plane message includes section extension information. The RU is further configured to transmit the control plane message, The DU according to claim 11, wherein the section extension information indicates the regularizationFactor.

14. Section Type 5 is defined in O-RAN (open-radio access network), The regularizationFactor is transmitted from the DU to the RU, based on the capabilities of the RU, instead of Section Type 6 of the channel information. The DU according to claim 11, wherein the regularization factor relates to the noise variance used in the calculation of the MMSE.

15. The section extension information includes information about the type of section extension information and information about the length of the section extension information, The type of the section extension information relates to the regularizationFactor, and The DU according to claim 13, wherein the length of the regularizationFactor is 16 bits.

16. In wireless communication systems, the RU (radio unit) of a base station is, Transceiver and It includes a controller coupled to the aforementioned transmitting and receiving unit, The aforementioned controller, It is configured to receive management plane messages from a Distributed Unit (DU) to set the regularizationFactor in Section Type 5 regarding terminal (user equipment, UE) scheduling information. The aforementioned regularizationFactor is an RU used in MMSE (minimum mean square error) calculations to generate multi-user (MU) beamforming weights for terminals on a per-slot basis.

17. The RU according to claim 16, wherein the management plane message is received based on the capability of the RU.

18. The aforementioned controller, The DU receives a control plane message of Section Type 5 relating to the terminal scheduling information, and the control plane message includes section extension information. Identify the section extension information indicating the regularizationFactor, and The RU according to claim 16, further configured to obtain a beamforming weight value based on the regularization factor.

19. Section Type 5 is defined in O-RAN (open-radio access network), The regularizationFactor is transmitted from the DU to the RU, based on the capabilities of the RU, instead of Section Type 6 of the channel information, and The regularization factor is the RU according to claim 16, relating to the noise variance used in the calculation of the MMSE.

20. The section extension information includes information about the type of section extension information and information about the length of the section extension information, The type of the section extension information relates to the regularizationFactor, and The RU according to claim 18, wherein the length of the regularizationFactor is 16 bits.

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