Transmission method and apparatus for MIMO system

Abstract

To provide a communication technique for convergence between an IoT technology and a 5th generation (5G) communication system for supporting a higher data transmission rate beyond a 4th generation (4G) system, and a system thereof.SOLUTION: A method includes intelligence services on the basis of a 5G communication technology and an IoT-related technology. A method of a digital unit (DU) of a base station includes the steps of: determining a scheduling-related parameter for at least one user; and transmitting scheduling information indicating the scheduling-related parameter to a radio unit (RU). The scheduling information may include a first section extension field including information on a user equipment identifier (ueID) related to the at least one user, and a second section extension field including information on the number of ueIDs corresponding to each user.SELECTED DRAWING: Figure 15a

Description

[Technical Field]

[0001] The present invention relates to wireless communication systems, and more particularly to a method and apparatus for transmitting, receiving, and processing control messages. [Background technology]

[0002] Efforts are underway to develop improved fifth-generation (5G) or pre-5G communication systems to meet the increasing demand for wireless data traffic since the commercialization of fourth-generation (4G) communication systems. For this reason, 5G or pre-5G communication systems are referred to as beyond-4G network (Beyond 4G Network) communication systems or post-LTE (Long-term Evolution) systems. To achieve high data transmission rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., the 60 GHz band). To mitigate propagation path loss and increase transmission distance in ultra-high frequency bands, beamforming, massive multiple-input multiple-output (MM-MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna technologies are being discussed for 5G communication systems. Furthermore, to improve the system's network, technologies such as advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication, wireless backhaul, moving networks, cooperative communication, CoMP (Coordinated Multi-Point), and receiver interference cancellation are being developed for the 5G communication system.In addition, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding) are being developed for 5G systems, as well as advanced connection technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access).

[0003] Meanwhile, the Internet, a human-centered network where humans generate and consume information, is evolving into the Internet of Things (IoT), a network in which distributed components such as objects exchange and process information without human intervention. IoE (Internet of Everything) technology has also emerged, combining IoT technology with big data processing technology through connections to cloud servers. Realizing the IoT requires technological elements such as sensing technology, wired / wireless communications and network infrastructure, service interface technology, and security technology. Recently, research has focused on sensor networks, M2M (Machine to Machine), and MTC (Machine Type Communication) for connecting objects. In an IoT environment, intelligent IT (Internet Technology) services can be provided that create new value in people's lives by collecting and analyzing data generated by connected objects. Through the convergence and integration of existing IT (information technology) technologies and various industries, IoT can be applied to areas such as smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0004] As a result, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, M2M (Machine to Machine), and MTC (Machine Type Communication) can be implemented in 5G communication technologies using techniques such as beamforming, MIMO, and array antennas. The application of cloud radio access network (Cloud RAN) as the aforementioned big data processing technology can also be seen as an example of convergence between 5G and IoT technologies.

[0005] Base stations providing mobile communication services have traditionally been integrated with a base station data processing unit or digital unit (DU) and a radio transceiver unit or radio unit (RU) installed at the cell site. However, this type of base station did not meet the needs of mobile communication operators who were building multiple cell sites to accommodate the increase in users and traffic. As a result, an improved C-RAN (centralized RAN (radio access network) or cloud RAN) structure has emerged. A C-RAN centralizes DUs in one physical location, leaving only RUs at the cell site that actually transmit and receive radio signals with terminals. The DU and RU can be connected via optical or coaxial cables. Separating the RU and DU requires an interface standard for communication between them, and standards such as the Common Public Radio Interface (CPRI) are currently used between the RU and DU. The 3GPP (3rd Generation Partnership Project) is also standardizing this base station structure and is researching the Open Radio Access Network (O-RAN), an open network standard that can be applied to 5G systems.

[0006] In addition, research is currently being conducted into the fifth generation communication system (hereinafter referred to as the 5G system, which may be interchangeably referred to as the NR (new radio) or next radio) system) to meet the demand for wireless data traffic. It is expected that the 5G system will be able to provide users with high data transmission rate services, and that it will also be able to provide wireless communication services with a variety of purposes, such as the Internet of Things and services that require high reliability for specific purposes.

[0007] MIMO (Multiple Input Multiple Output) is a technology in which transmitters and receivers communicate using multiple antennas, and it has been theoretically proven that the capacity of a MIMO system increases in proportion to the number of antennas. Due to its advantage of being able to increase transmission volume in a relatively simple manner, MIMO has been standardized and used in a variety of communication and broadcasting systems. Massive MIMO, which has been attracting attention in recent years, can effectively eliminate interference between multiple users by beamforming using multiple antennas, and is positioned as a core technology for 5G mobile communications.

[0008] Additionally, for efficient data transmission in terms of a large-capacity MIMO system, the transmitter is function-split into a DU (Digital Unit) and RU (Radio Unit). In this function-split structure, the DU performs digital signal processing, while the RU is responsible for D / A (Digital-to-Analog) conversion and analog signal transmission. However, in order to meet the requirements of various services and systems in recent years, standards such as ORAN (Open Radio Access Network) have defined interfaces for each type of function-split structure, and active discussions are currently underway regarding the interfaces required for functional separation between the DU and RU through the issuance of standards.

[0009] The above information is provided merely as background information to aid in the understanding of the present disclosure, and no determination or assertion is made as to whether any of the above content can be applied as prior art to the present disclosure. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a transmission method for a multi-user MIMO (multiple-input multiple-output) system with channel feedback. Generally, a transmitting end can apply precoding that can provide beam gain to a desired user while canceling interference effects on multiple users occurring in the downlink using channel information received from a receiving end. The present invention proposes a precoding system for multi-user precoding and defines an interface between a digital unit (DU) and a radio unit (RU) required to actually implement the system. [Means for solving the problem]

[0011] According to one embodiment of the present invention, there is provided a method for a base station digital unit (DU), comprising: determining scheduling-related parameters for at least one user; and transmitting scheduling information indicating the scheduling-related parameters to a radio unit (RU), wherein the scheduling information includes a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs corresponding to each user.

[0012] According to another embodiment of the present invention, the scheduling-related parameters may include at least one of at least one ueID corresponding to each user, the number of ueIDs corresponding to each user, the number of the at least one user to be scheduled, and the number of layers for each user.

[0013] According to another embodiment of the present invention, the first section extension field may include the same ueID for each of the at least one user repeatedly as many times as the number of layers of the user.

[0014] According to another embodiment of the present invention, the first section extension field may include ueIDs that are as different from each other as the number of the at least one users scheduled via the scheduling information.

[0015] According to another embodiment of the present invention, at least one ueID corresponding to each user may have consecutive values ​​equal to the number of ueIDs corresponding to each user.

[0016] According to another embodiment of the present invention, there is provided a method for a base station radio unit (RU), comprising: receiving scheduling information indicating scheduling-related parameters for at least one user from a digital unit (DU); and acquiring the scheduling-related parameters based on the scheduling information, wherein the scheduling information includes a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs for each user.

[0017] According to another embodiment of the present invention, there is provided a digital unit (DU) device of a base station, the DU device including: a connector for transmitting and receiving signals to and from a radio unit (RU); and at least one processor for determining scheduling-related parameters for at least one user and controlling transmission of scheduling information indicating the scheduling-related parameters to the RU, wherein the scheduling information includes a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs corresponding to each user.

[0018] According to another embodiment of the present invention, there is provided a radio unit (RU) device of a base station, the RU device including: a connector for transmitting and receiving signals to and from a digital unit (DU); and at least one processor for receiving scheduling information indicating scheduling-related parameters for at least one user from the DU and controlling to acquire the scheduling-related parameters based on the scheduling information, wherein the scheduling information includes a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs for each user. [Effects of the Invention]

[0019] According to an embodiment of the present invention, a transmission method for a multi-user MIMO system is provided. The transmission method for the multi-user MIMO system includes channel feedback. Specifically, a system for multi-user precoding is proposed, and an interface between a DU and a RU required for actually implementing the system is defined.

[0020] Other embodiments, advantages and salient features of the present invention will become apparent to those skilled in the art from the detailed description of the invention taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0021] The above and other aspects, features, and advantages of any embodiment of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings: [Figure 1] 1 is a diagram illustrating an open-radio access network (O-RAN) network system according to an embodiment of the present invention. [Figure 2] 1 is a diagram illustrating a low layer function split through a radio unit (RU) and a digital unit (DU) according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing a format of a message transmitted between an RU and a DU according to an embodiment of the present invention. [Figure 4] 1 is a diagram illustrating an Ethernet message standard according to an embodiment of the present invention. [Figure 5] 1 is a diagram illustrating an enhanced common public radio interface (eCPRI) header format according to an embodiment of the present invention. [Figure 6] 1 is a diagram showing the flow of control messages or data transmitted via C-plane and U-plane messages according to an embodiment of the present invention. [Figure 7] 10 is a diagram showing a C-Plane message format of section type 5 according to an embodiment of the present invention. [Figure 8] 1 is a diagram showing a message format of section extension type 10 according to an embodiment of the present invention. [Figure 9] 10 is a diagram showing a C-Plane message format of section type 6 according to an embodiment of the present invention. [Figure 10]1 is a diagram illustrating a first operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 11] 10 is a diagram illustrating a second operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 12] 10 is a diagram illustrating a third operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 13] 10 is a diagram illustrating a fourth operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 14] 10 is a diagram showing a fifth operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 15a] 10 is a diagram showing a sixth operation of a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 15b] 1 is a diagram illustrating a message format for transmitting scheduling information according to an embodiment of the present invention. [Figure 16] 10 is a diagram illustrating a message format for transmitting weights or channel transformation matrices according to an embodiment of the present invention. [Figure 17] 3 is a flowchart illustrating an operation of a digital unit (DU) according to an embodiment of the present invention. [Figure 18] 3 is a flowchart illustrating the operation of a radio unit (RU) according to one embodiment of the present invention. [Figure 19] 1 is a diagram showing the structure of a DU and an RU according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] It will be understood that throughout the drawings, like reference numerals refer to like parts, components and structures.

[0023] The following description, which refers to the accompanying drawings, is provided to facilitate a comprehensive understanding of various embodiments of the present invention, as defined by the claims and their equivalents. It includes various specific details to facilitate understanding, but these should be considered as examples only. Therefore, those skilled in the art will understand that various modifications and alterations to the various embodiments described in the present invention can be made without departing from the scope and spirit of the present disclosure. Furthermore, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

[0024] The terms and phrases used in the following description and claims are not limited to their bibliographical meanings, but are merely used by the inventor to provide a clear and consistent understanding of the disclosure. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only, not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

[0025] The singular forms "a," "an," and "the" should be understood to include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "surface of a component" includes reference to one or more of such surfaces.

[0026] It will be understood that the combination of each block of the process flowchart and the flowchart figures can be implemented by computer program instructions. These computer program instructions can be loaded onto a processor in a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that the instructions, executed by the processor of the computer or other programmable data processing device, create means for performing the functions described in the flowchart blocks. These computer program instructions can also be stored in computer-usable or computer-readable memory that can direct the computer or other programmable data processing device to implement functions in a particular manner, such that the instructions stored in the computer-usable or computer-readable memory can produce an article of manufacture containing instruction means for performing the functions described in the flowchart blocks. Computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operations are performed on the computer or other programmable data processing device to create a computer-implemented process, causing the computer or other programmable data processing device to execute the instructions to provide operations for performing the functions described in the flowchart blocks.

[0027] Also, each block may represent a module, segment, or portion of code that includes one or more executable instructions for performing a specified logical function. Also, it should be noted that in some alternative implementations, the functions described in the blocks may occur out of order. For example, two blocks shown adjacently may actually be performed substantially simultaneously, or the blocks may sometimes be performed in reverse order depending on the corresponding function.

[0028] In this embodiment, the term 'module' refers to software or a hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the 'module' may perform any function. However, the 'module' is not limited to software or hardware. The 'module' may be configured to reside on an addressable storage medium or to implement one or more processors. Thus, by way of example, the 'module' includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and 'modules' may be combined into fewer components and 'modules' or further separated into additional components and 'modules'. Furthermore, the components and 'modules' may be implemented to implement one or more CPUs within a device or a secure multimedia card.

[0029] Hereinafter, in the present invention, uplink (UL) refers to a radio link through which a terminal transmits data or control signals to a base station, and downlink (DL) refers to a radio link through which a base station transmits data or control signals to a terminal. The base station is a subject that allocates resources to terminals and may be at least one of an eNode B, a Node B, a Base Station (BS), a gNB (generation Node B) radio access unit, a base station controller, or a node on a network. The terminal may include a User Equipment (UE), a Mobile Station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions.

[0030] To meet the demand for wireless data traffic, the fifth generation communication system is being commercialized, providing users with high data transmission rate services through the 5G system, just like the 4G system. It is also expected that wireless communication services for various purposes, such as the Internet of Things and services requiring high reliability for specific purposes, will be provided.

[0031] The Open Radio Access Network Alliance (O-RAN), established by operators and equipment providers to support a network system that combines 4G and 5G systems, is defining new network elements (NEs) and interface standards based on 3GPP® standards, resulting in the emergence of the Open Radio Access Network (O-RAN) architecture. O-RAN redefines the 3GPP® NEs (RU, DU, central unit-control plane (CU-CP), and central unit-user plane (CU-UP)) as O-RU, O-DU, O-CU-CP, and O-CU-UP, respectively (which can be combined to form the O-RAN base station). Additionally, it also standardizes the RAN Intelligent Controller (RIC) and non-real-time RAN Intelligent Controller (NRT-RIC). Ethernet connections are available between the O-DU and RIC, between the O-CU-CP and RIC, and between the O-CU-UP and RIC. In addition, interface standards are required for communication between each O-DU and RIC, between the O-CU-CP and RIC, and between the O-CU-UP and RIC, and current standards such as E2-DU, E2-CU-CP, and E2-CU-UP can be used between the O-DU, O-CU-CP, O-CU-UP, and RIC. Hereinafter, the terms RU, DU, CU-CP, and CU-UP described in this specification can be used interchangeably with O-RU, O-DU, O-CU-CP, and O-CU-UP, respectively, unless otherwise specified.

[0032] FIG. 1 is a diagram of an O-RAN network system according to an embodiment of the present invention.

[0033] As shown in Figure 1, the O-RAN network is a standard that logically separates the eNB and gNB functions of 4G and 5G systems, and the O-RAN standard defines the NRT-RIC 110, RIC 120 within the O-RAN gNB 100, O-CU-CP 130, O-CU-UP 140, O-DU 150, and O-RU 160.

[0034] The NRT-RIC 110 is a logical node that enables non-real-time control, optimization of RAN elements and resources, model training, and updates. The newly defined RIC 120 is a logical node that centralizes servers in one physical location and enables near-real-time control and optimization of RAN elements and resources based on data collected from the O-DU 150, O-CU-CP 130, O-CU-UP 140, etc. via the E2 interface. The O-CU, including the O-CU-CP 130 and O-CU-UP 140, is a logical node that provides radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocol functions. The O-CU-CP 130 is a logical node that provides the control plane functions of RRC and PDCP, and the O-CU-UP 140 is a logical node that provides the user plane functions of SDAP and PDCP. The O-CU-CP 130 is connected to the access and mobility management function (AMF) included in the 5G network (5G core) via an NGAP interface. The O-DU 150 is a logical node that provides RLC, MAC, and high-PHY functions, and the O-RU 160 connected to the O-DU 150 is a logical node that provides low-PHY functions and RF processing. Although each logical node is illustrated as a single node in FIG. 1, multiple logical nodes can be connected. For example, multiple O-RUs 160 can be connected to one O-DU 150, and multiple O-DUs 150 can be connected to one O-CU-UP 140.

[0035] The present invention is not limited by the names of the nodes described above, and the configuration of the present invention can be applied to any logical node or entity that performs the described functions. Furthermore, the logical nodes can be located in the same physical location or in different locations, and their functions can be provided by the same physical device (e.g., processor, controller, etc.) or by different physical devices. For example, the functions of at least one of the logical nodes described above can be provided through virtualization in one physical device. Hereinafter, O-DU and O-RU can be used interchangeably as DU and RU, respectively.

[0036] FIG. 2 is a diagram illustrating a low layer function split between an RU and a DU according to an embodiment of the present invention.

[0037] Referring to Figure 2, the RU and DU can be connected via a fronthaul (FH), where the RU and DU can perform their respective physical layer functions separately.

[0038] In a 4G or 5G communication system, the physical layer for the downlink receives downlink data at the MAC layer (236), performs channel coding and scrambling on the received data (234), modulates the scrambled data (232), and then performs layer mapping of the modulation symbols (230). The modulation symbols mapped to each layer are mapped to each antenna port (228), mapped to the corresponding resource element (RE, a resource allocation unit consisting of one subcarrier and one symbol) (226), and then digital beamforming (which may be combined with precoding) is performed (224). An inverse fast Fourier transform (IFFT) is performed to transform the signal into a time domain signal, and a cyclic prefix (CP) is added (222). The signal is then transmitted to a carrier frequency at the RF (220) and transmitted to a terminal via an antenna. In addition, in a 4G or 5G communication system, in the physical layer for uplink, a carrier frequency signal received through an antenna is converted to a baseband signal in the RF (240), the converted signal is transformed into a frequency domain signal through CP removal and FFT (242), the applied digital beamforming is inversely applied to combine the uplink signal (244), the signal is demapped (246) in the RE to which the uplink signal is mapped, channel estimation (248) is performed, layer demapping (250) is performed to demodulate the aligned modulation symbols (252), and the bit sequence obtained as a result of the demodulation is descrambled and decoded to obtain information bits (254), which are then transmitted to the MAC layer (256).

[0039] There are various options for dividing lower layer functions, and examples of these are shown in Figure 2, including Option 6 (212), Option 7-3 (210), Option 7-2 (208), Option 7-2x Category B (202), Option 7-2x Category A (200), Option 7-1 (206), and Option 8 (204). It can be understood that the functions on the right side of an option are performed by the DU, and the functions on the left side are performed by the RU. For example, CPRI in an LTE system corresponds to Option 8. In the downlink, the DU performs all the physical layer processes shown in Figure 3, and the RU transmits the signal via the FH. The RU only performs the process of converting the received signal to an analog signal and transmitting it to the terminal. However, the more functions the DU performs, the larger the required fronthaul bandwidth. Therefore, O-RAN can support Option 7-2x Category B (202) and Option 7-2x Category A (200).

[0040] Specifically, Option 7-2x Category A (200) is the capability category of an O-RU that cannot process precoding of data received from the O-DU, while Option 7-2x Category B (202) is the capability category of an O-RU that can process precoding of data received from the O-DU. For example, an O-DU must support Category A O-RU for up to eight transmit streams. In other words, an O-DU supports precoding for up to eight transmit streams. In this case, when Option 7-2x Category B (202) is applied, the O-DU transmits information on modulation symbols that have already been layer mapped and beamforming information to the O-RU. The O-RU then applies beamforming to the modulation symbols, converts them into analog signals, and transmits them via the UE antenna.

[0041] There are four types of information that the O-DU in Option 7-2x should transmit to the O-RU. Information transmitted from the management plane (M-plane) is transmitted in non-real-time in both DL and UL directions and is information for initial setup and reset between the O-DU and O-RU. Information transmitted from the synchronization plane (S-plane) is transmitted in real time and is information for synchronization or timing between the O-DU and O-RU. Information transmitted from the control plane (C-plane) is transmitted in real time in the DL direction and is information for the O-DU to send scheduling and / or beamforming commands to the O-RU. Information transmitted from the user plane (U-plane) is transmitted in real time in both DL and UL directions and is DL frequency domain IQ data (including synchronization signal blocks (SSBs) and reference signals), UL frequency domain IQ data (including reference signals such as sounding reference signals) and frequency domain IQ data for the physical random access channel (PRACH) transmitted in the U-plane. The information or data may be mixed with the message.

[0042] Next, the information transmitted between the O-RU and the O-DU will be described in more detail.

[0043] FIG. 3 is a diagram illustrating a format of a message transmitted between an O-RU and an O-DU according to an embodiment of the present invention.

[0044] 3, the O-RU and O-DU are connected via Ethernet, and the Ethernet message standard is the same as 300. The payload of the Ethernet message includes a message formatted according to each plane, for example, the C-plane format is the same as 330. The C-plane format 330 includes an eCPRI (enhanced CPRI) header 310 and an O-RAN header 320. The payload may also include information in a U-plane format 340 or a format according to another plane.

[0045] FIG. 4 is a diagram showing an Ethernet message standard according to an embodiment of the present invention.

[0046] 4, in the header of the Ethernet message, Destination MAC address 400 indicates the public address of the RU or MMU (massive MIMO unit) in the case of DL, and indicates the public address of a specific port of the DU channel card (channel card, which can perform MAC (medium access control) layer operations responsible for scheduling, high-PHY (upper physical layer) operations, and data format conversion operations via the interface between the RU and DU) in the case of UL. Source MAC Address 410 indicates the public address of the RU or MMU in the case of UL, and indicates the public address of a specific port of the DU channel card in the case of DL.

[0047] The VLAN tag 420 is 4 bytes long and can map and manage C, U, or S-plane messages to different VLAN tags. The 16-bit TPID (Tag protocol identifier) ​​included in the VLAN (virtual LAN) tag is set to 0x8100 to identify the frame as an IEEE 802.1Q tagged frame. This field is located in the same position as the Ethertype / Length field 430 in untagged frames and is used to distinguish untagged frames from regular frames. The 16-bit TCI (Tag control information) included in the VLAN tag contains the following three fields: The 3-bit PCP (Priority code point) represents the frame priority; the 1-bit DEI (Drop eligible indicator) is used separately from the PCP or in combination with it to identify frames that can be dropped when traffic is congested; and the 12-bit VID (VLAN identifier) ​​indicates which VLAN the frame belongs to. All values ​​except the reserved values ​​0x000 and 0xFFF are used as VLAN identifiers, allowing up to 4,094 VLANs. The reserved value 0x000 indicates that the frame does not belong to any VLAN, in which case 802.1Q specifies only the priority and can refer to it with the priority tag. Type / Length (Ethertype) 430 is set to a fixed value of 0xAEFE because it is for eCPRI.

[0048] The payload 440 may include a message in each plain format including the eCPRI header as shown in Figure 3. Not all fields or information contents described with reference to Figure 4 must be included, and the present invention may be implemented by omitting or / and adding other fields as necessary.

[0049] 5 is a diagram showing the format of an eCPRI header according to an embodiment of the present invention. The eCPRI header is a transport header located before the Ethernet payload (440 in FIG. 4).

[0050] 5, the eCPRI header is 8 bytes in total, ecpriVersion 500 is 4 bits and uses a fixed value of 0001b, ecpriReserved 510 is 3 bits and uses a fixed value of 0000b, ecpriConcatenation 520 is 1 bit and uses a fixed value of 0b, and ecpriMessage 530 is 1 byte and indicates the message type. For the U-plane, the value 0000 0000b (0x0) is used, for the C-plane, the value 0000 0010b (0x2) is used, and for eCPRI delay measurement, the value 0000 0101b (0x5) can be used.

[0051] ecpriPayload 540 is 2 bytes and indicates the payload size in bytes, and ecpriRtcid / ecpriPcid 550 is 2 bytes and the number of bits for each field (described later) can be set via the M-plane setting. CU_Port_ID (x bits) included in ecpriRtcid / ecpriPcid 550 identifies the RU channel card and can also identify the modem. In this case, 2 bits can be used to identify the channel card and 2 bits can be used to identify the modem. BandSector_ID (y bits) can indicate the corresponding cell or sector. CC_ID (z bits) can indicate the corresponding component carrier. RU_Port_ID (w bits) can be set to identify layers, antennas, etc.

[0052] The ecpriSeqid 560 is a 2-byte sequence identifier (sequence ID) managed separately from the ecpriRtcid / ecpriPcid 550, and the sequence ID and subsequence ID are managed separately. Radio-transport-level fragmentation is possible using the subsequence ID. The contents of each field or information described with reference to FIG. 5 do not necessarily have to be included, and the present invention can be implemented by omitting and / or adding other fields as necessary.

[0053] Next, we will describe C-plane messages in detail.

[0054] FIG. 6 is a diagram illustrating a flow of control messages or data being transmitted via C-plane and U-plane messages according to an embodiment of the present invention.

[0055] Referring to FIG. 6, the O-DU 604 transmits a control message (C-plane) message for U-plane data of slot #n to the O-RU 602 (600). The C-plane message is an eCPRI message type 2, and six sectionType messages are used to transmit allocation information for sections and beamforming information corresponding to each section. A section refers to an area in one slot to which RB resources having the same beam pattern are contiguously allocated, and U-plane data for each section can be transmitted. Generally, one section can include 12 REs (or subcarriers) (i.e., 1 to 273 resource blocks (RBs)) on the frequency axis and can be a rectangular rectangle of 1 to 14 symbols on the time axis. This can include contiguous or non-contiguous allocation. If the bits applied within the 12 REs (1 RB) change, one section can be divided by multiple REMasks with different bit patterns.

[0056] The following six section types can be supported:

[0057] sectionType=0: Indicates a DL idle / guard interval, which is for transmission blanking to save power.

[0058] sectionType=1: Used to map beamforming indexes and weights to REs of DL and UL channels. This is a mandatory beamforming method supported by O-RAN.

[0059] sectionType=3: Used to map beamforming indices and weights to REs for PRACH and mixed-numerology channels.

[0060] sectionType=5: RU is used to convey UE scheduling information to enable real-time beamforming weight calculation, which is an optional beamforming method supported in O-RAN.

[0061] sectionType=6: The RU is used to periodically transmit UE channel information to enable real-time beamforming weight calculation. This is an optional beamforming method supported by O-RAN.

[0062] sectionType=7: This is used for LAA (licensed assisted access) support.

[0063] The O-DU 604 that transmitted the C-plane message transmits IQ data for each OFDM symbol of slot #n using a U-plane message (610, 612, 614). The U-plane message transmits IQ data (and reference signal, SSB) and PRACH IQ data for the user using an eCPRI message type 0. There are two data formats for the U-plane data. For DL / UL user data, a static data format, the IQ format and compression method are fixed, and are set by an M-Plane message at the time of RU initialization. For DL / UL user data, a dynamic data format, the IQ format and compression method can be changed dynamically, and are set by a DL U-Plane message and a UL C-Plane message.

[0064] Thereafter, the O-DU 604 transmits a C-plane message for the U-plane data of slot #n+1 in the O-RU 602 (620). Thereafter, the O-DU 604 transmits IQ data for each OFDM symbol of slot #n+1 in a U-plane message in the O-RU 602 (630, 632, 634).

[0065] Although the case of DL transmission is illustrated in Figure 6, UL transmission can be performed in a similar manner. Specifically, the O-DU transmits a C-plane message, and the O-RU that receives this transmits IQ data for each symbol of the corresponding slot in a U-plane message from the O-DU.

[0066] In this invention, a transmission method for a multi-user MIMO system with channel feedback is proposed, and the interface required for implementing this technology is defined in the ORAN standard.

[0067] To this end, we will first briefly introduce the zero-forcing (ZF) based MIMO transmission method supported by ORAN and the associated interface between DU and RU.

[0068] To explain the ZF-based MIMO transmission method, the number of transmitting antennas is N t , the number of receiving end antennas per receiving user is N r,k If K is the number of users, the sender can send K

number

[0069] [Formula 1]

[0070]

number

[0071] The transmitter for convenience of mathematical expansion is

number

number

[0072] ORAN defines the format of control information transmitted from the DU to the RU via the C-plane interface, and information related to ZF MIMO transmission is defined in Section Type 5 or Section Type 6. Section Type 5 includes the interface required when the DU transmits scheduling information including the scheduled user index to the RU after scheduling based on channel information. There are two ways for the DU to acquire channel information. The first is for the RU to process the Sounding Reference Signal (SRS) and transmit the channel information to the DU. The second is for the DU to process the SRS and acquire the channel information. In the second case, the DU can transmit the channel information to the RU, and the interface required for this is included in Section Type 6.

[0073] FIG. 7 is a diagram illustrating a C-Plane message format of section type 5 according to an embodiment of the present invention.

[0074] Referring to FIG. 7, a section type 5 (sectionType=5) message format 700 may include an information field used to transmit UE scheduling information so that the RU can perform real-time beamforming weight calculation.

[0075] The transport header may be the eCPRI header shown in Fig. 5 or information according to IEEE-1914.3. DataDirection 702 indicates the direction of the U-Plane message, with 0 indicating UL and 1 indicating DL.

[0076] The filterIndex 704 indicates the channel filter of the RU and can be set to 0x1. The frameId 706 indicates a specific frame in 10 ms units. The subframeId 708 indicates a specific subframe in 1 ms units within the corresponding frame. The slotId 710 indicates a specific slot within the corresponding frame.

[0077] The numberOfsections 714 indicates the number of sections indicated by the message. In the case of SectionType 716, one C-plane message can have only one section type. The udCompHdr 718 indicates the IQ bit width (bits) and compression method for the IQ data of all sections of the message. Specifically, the upper 4 bits indicate 1 to 16 bits as iqWidth, and the lower 4 bits indicate the compression method as compMeth.

[0078] A C-plane message of section type 5 includes information about an optional section. SectionID 722 indicates the section ID, which can be used to match C-plane messages with U-plane messages. rb 724 indicates which PRB is used, with 0 indicating that all PRBs are used and 1 indicating that every other PRB is used. StartPrbc 726 is used to indicate the first PRB of the section, and numPrbc 728 is used to indicate the number of PRBs in the section. reMask 730 is a bit pattern that indicates the RE (or subcarrier) corresponding to a specific beam in the PRB. Different beams can be applied within one PRB via reMask. numSymbol 732 indicates the number of symbols corresponding to the section, and ef 734 can indicate whether there is a section extension after the section. The C-plane message can also include a section extension, and whether a section extension is included can be indicated by ef 720. The contents of each field or information described with reference to FIG. 7 do not necessarily have to include all fields, and the present invention can be carried out by omitting or / and adding other fields as necessary.

[0079] The aforementioned section type 5 (ST5) frame is defined to carry only one ueId (user equipment identifier) ​​within a specified resource (indicated by startPrbc, numPrbc, symInc, etc.), and the corresponding layer information can be set to the eAxC value in the transport header. The ueID is a parameter indicating the label of the UE to which the contents of the section apply and can be used to support channel information transmitted from the O-DU to the O-RU. The ueID merely functions as a UE label; a specific value does not have a specific meaning depending on the UE type that can be supported within the system. Meanwhile, for ZF MIMO transmission, multiple ueID information must be allocated to the same resource. For this reason, two methods can be considered. The first method is to transmit ueID information for the number of frames by setting different eAxC values ​​in the transport header and transmitting the ST5 frame multiple times. The second method is to utilize section extension (SE). For example, after setting the ef (extension flag) value to 1 as shown in FIG. 7, a section extension frame can be added to set and transmit multiple ueID information at once. The section extension may convey beamforming weights, beamforming attributes, precoding settings and parameters, modulation compression related parameters, non-contiguous PRB allocation information, or multiple eAxCs (extended antenna-carriers, digital baseband user planes required for receiving or transmitting one carrier with one independent antenna element, which can mean transmission for each layer). Various types may be supported depending on the purpose, but below, Figure 8 describes section extension type 10 (SE10).

[0080] FIG. 8 shows a diagram illustrating a message format of a section extension type 10 according to an embodiment of the present invention.

[0081] The section extension 800 may include the following fields: ef 802 indicates whether other section extensions are included sequentially, and extType 804 indicates the type of section extension. In FIG. 8, extType=0x0y indicating SE10 is illustrated as an example. At this time, beamGroupType is 10b. extLen 806 may indicate the length of the section extension in 4-byte units. The numPortc value indicates the total number of ueIDs assigned to the SE, and ueID information may be set consecutively as shown in FIG. 8. The contents of each field or information described with reference to FIG. 8 do not necessarily have to be included, but may be omitted and / or other fields may be added as necessary to implement the present invention.

[0082] FIG. 9 is a diagram illustrating a C-Plane message format of section type 6 according to an embodiment of the present invention.

[0083] Referring to FIG. 9, a section type 6 (sectionType=6) message format 900 is used to periodically transmit UE channel information so that an RU can perform real-time beamforming weight calculation, and may include information fields. The transport header may be the eCPRI header shown in FIG. 5 or information according to IEEE-1914.3. The dataDirection 902 indicates the direction of the U-Plane message, with 0 indicating UL and 1 indicating DL. Section Type 6 is used to transmit complex channel values ​​for all RBs (Resource Blocks) and antennas for the corresponding ueId. In this case, the complex channel values ​​may be I and Q values ​​of ciISample / ciQSample channel information. The other parameters may correspond to the contents described in Section Type 5 described with reference to FIG. 7. Not all fields or information contents described with reference to FIG. 9 must be included, and the present invention may be implemented by omitting and / or adding other fields as necessary.

[0084] Meanwhile, the recent standardization of uplink Transmit Antenna Selection (TAS) in cellular communications has increased the feasibility of transmitting not only a single stream per user but also multiple streams when applying beamforming to single-user (SU) / multi-user (MU)-MIMO. While the ZF beamforming technique mentioned above is a relatively simple method, it can result in performance loss due to the removal of both other users' channels and the channel interference within a single user. To prevent this loss, subspace decomposition or channelization of the channel matrix can be considered, but implementing this technology requires a new interface in the ORAN standard.

[0085] The present invention relates to a beamforming technique that reduces multi-user interference or co-channel (between transmission layers) interference within a single user through channel decomposition and transformation using a channel estimated by utilizing TAS in the communication physical layer. In particular, the present invention proposes an interface between DU and RU required for practical implementation of the technology.

[0086] First, in SU-MIMO transmission, appropriate weights can be generated through subspace decomposition or channelization of the user channel matrix. When the number of layers for SU transmission is L, the weights W SU teeth

number

[0087] Next, in MU-MIMO transmission, the ZF weight generation method is basically used to eliminate interference between multiple users, but in order to obtain combining gain within each user,

number

number

number

number

[0088] The present invention relates to the W SU and X k We propose an interface for transmitting information related to W SU and X kWe propose a method for defining the required interfaces depending on whether the DU or RU generates the DU or RU.

[0089] (1)RU with W SU and X k If

[0090] RU and W SU and X k If generated, DU is RU is W SU and X k The scheduling information transmitted from the DU to the RU can be transmitted via the section type 5 C-Plane message described above with reference to FIG. 7. Meanwhile, the RU can transmit the necessary scheduling information to the RU to generate W. SU and X k To generate H or H corresponding to each user channel, k However, currently, in the ORAN standard, when transmitting ueIDs, information on which user channel each ueID belongs to is not transmitted. In the present invention, an interface is disclosed for a DU to transmit ueID group information (i.e., information for grouping ueIDs corresponding to each user) corresponding to each user channel and information on the number of transmission layers for each user to an RU.

[0091] The first method for transmitting ueID group information corresponding to each user channel and information on the number of transmission layers for each user is to add a new section extension (SE) to each ST5 frame to transmit the user information, which will be described below with reference to Figure 10.

[0092] FIG. 10 is a diagram illustrating a first operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0093] Referring to Figure 10, the first operation 1000 discloses a method of transmitting user information by adding a new section extension (SE) to each ST5 frame corresponding to each ueID. In the first method, a virtual user ID can be defined and used as a method for indicating which user the ueID of each section frame belongs to, or a ueID representing each user (denoted as representative ueID) can be used as the user ID, as shown in Figure 10. numUeID is the number of ueIDs corresponding to each user, and numLayers can indicate the number of transmission layers for each user. In addition, the total number of users, SU / MU operation distinction flag, etc. can be added for any special purpose.

[0094] The second method for transmitting ueID group information corresponding to each user channel and information on the number of transmission layers for each user is a method of transmitting ueID information and additional information (such as the number of layers assigned to a user) corresponding to all scheduled users via a section extension (SE) in one ST5 frame, which will be described below with reference to Figures 11 to 15 (Figures 15a and 15b). The SE used for the second method can be a new extension type, or an existing extension type (e.g., SE10) can be used.

[0095] FIG. 11 is a diagram illustrating a second operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0096] Referring to Figure 11, a second operation 1100 discloses a method for transmitting ueID group information and additional information using a new extension type. First, numUser indicates the total number of users assigned to the extension, numUeID indicates the number of ueIDs corresponding to each user, and numLayers indicates the number of transmission layers for each user. In the extension type defined through Figure 11, the ueID of the numUeId child can be set consecutively for each user. As with Figure 10, the total number of users, SU / MU operation distinction flag, etc. can be added for any special purpose.

[0097] 12 to 14 show an operation for extending a field using existing beamGroupType=10b or a new beamGroupType while using existing SE10. At this time, whether an extension field exists can be confirmed through the advBeamFlag value in the existing extension field.

[0098] FIG. 12 is a diagram illustrating a third operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0099] Referring to FIG. 12, in the third operation 1200, numPortc can be defined as a value related to the number of users by utilizing the existing SE10. Specifically, when advBeamFlag=1, the numPortc value of the existing area is used as the value of (total number of users - 1), and a representative ueID value for each user can be assigned to the existing area. Then, the representative ueID of each user and numUeID and numLayer information for each user can be given in the extension field, and the remaining numUeID-1 ueID information can be set. If SU transmission is performed, the numPortc value becomes 0, but this part is not taken into account in the existing beamGroupType=10b. Therefore, if beamGroupType=10b is used as is, a new operation can be defined to immediately refer to the information in the extension field when the numPortc value is 0. Alternatively, a new beamGroupType can be defined and used.

[0100] FIG. 13 is a diagram illustrating a fourth operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0101] 13, in the fourth operation 1300, numPortc can be defined as a value related to the total number of scheduling layers by utilizing the existing SE 10. Specifically, when advBeamFlag=1, the numPortc value of the existing extension field is used as the value of (total number of scheduling layers - 1), and ueIDs can be allocated to each user in the existing field as many times as the number of layers. The extension field is similar to the third operation 1200 (FIG. 12), but in this fourth operation 1300, only ueIDs that are not set in the existing field can be allocated when allocating ueIDs.

[0102] FIG. 14 is a diagram illustrating a fifth operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0103] 14, in the fifth operation 1400, numPortc can be defined as the total number of ueIDs of all users by utilizing the existing SE10. Specifically, when advBeamFlag=1, the numPortc value of the existing extension field is used as the value of (the number of ueIDs of all users - 1), and all ueID information corresponding to the existing field can be allocated. In addition, only the representative ueID, numUeID, and numLayer information of each user can be allocated to the extension field. However, in this case, since the numPortc value can exceed 64, it is also possible to define a new beamGroupType other than the existing beamGroupType=10b.

[0104] In the third to fifth operations, whether or not an extension field exists is determined based on the advBeamFlag value using the existing SE10, but the format of the extension field described with reference to Figures 12 to 14 can be defined as a new extension type similar to operation 2. In this case, the new extension type can be determined based on the ef value rather than the advBeamFlag value, and can additionally include ef, extType, extLen values, etc., similar to the first example.

[0105] FIG. 15a is a diagram illustrating a sixth operation of a message format for transmitting scheduling information according to an embodiment of the present invention.

[0106] Referring to FIG. 15a, if the ueID values ​​within a user are consecutive, it is sufficient to transmit only one representative ueID value for each user and transmit the numUeID and numLayer values. The sixth operation 1500 shown in FIG. 15a is an example of expressing 13 in an efficient format even assuming consecutive ueIDs within a user, and is an example of expressing it as a new extension using the ef value rather than advBeamFlag. In the sixth operation 1500, when numPortc ueID values ​​are assigned to the existing SE10 area, it can be assumed that all ueIDs for the same user are set to one representative ueID value. Then, the total number of users can be determined by the number of different representative ueID values, and the number of transmission layers for each user can be determined by the number of identical representative ueID values. Therefore, it is sufficient to transmit the number of numUeIDs for each user in the new extension. Although numUeID is represented as 4 bits in FIG. 15a, the size can be set to various values.

[0107] FIG. 15b is a diagram showing a message format for transmitting scheduling information according to an embodiment of the present invention.

[0108] Referring to FIG. 15b, the total number of scheduled users is assumed to be 2, and the maximum number of ueIDs that can be assigned to one user is assumed to be 8. Therefore, the ueID values ​​assigned to each user can have consecutive values ​​equal to the number of assigned ueIDs, starting from a multiple of 8. For the two assumed users described above, it is assumed that the number of transmission layers for the first user is 2, and the ueIDs assigned to the first user are four consecutive values, 0, 1, 2, and 3. It is assumed that the number of transmission layers for the second user is 3, and the ueIDs assigned to the second user are eight consecutive values, 8, 9, 10, ..., 15. In addition, it is assumed that the representative ueID for each user is the smallest value of the ueIDs assigned to each user as a multiple of 8, i.e., 0 for the first user and 8 for the second user. The specific situations and values ​​mentioned above are for illustrative purposes only and can be configured in various ways as needed.

[0109] Figure 15b illustrates specific parameter settings of a message format for efficiently conveying the total number of users, the number of transmission layers for each user, and the ueID assigned to each user by the sixth operation 1500 of the present invention in the situation assumed above.

[0110] As shown in Figure 15b, the SE10 field (extType = 0X0y) can include ueID values ​​corresponding to 0, 8, 8, 8. Although not shown in Figure 15b, ST5 to which the section extension (SE10) is applied also includes one ueID value, but ST5 can include ueID = 0 corresponding to the first user. Therefore, a total of five ueIDs (0, 0, 8, 8, 8) can be transmitted. Furthermore, the new SE field (New extType) can include the number of ueIDs assigned to the first user (numueID of 1st user = 4) and the number of ueIDs assigned to the second user (numueID of 2nd user = 8).

[0111] The method by which an RU receiving the message format shown in FIG. 15b obtains information on the total number of users, the number of transmission layers for each user, and the ueID assigned to each user is as follows.

[0112] As described with reference to FIG. 15a, the number of different representative ueIDs (i.e., 0 and 8) in the illustrated message format indicates the total number of users. For example, RU identifies that the total number of scheduled users is 2 in the example of FIG. 15b. Also, the number of times the same representative ueID value is repeatedly set (i.e., ueID=0 twice, ueID=0 twice, and ueID=8 three times) indicates the number of transmission layers for each user. For example, RU identifies that the number of transmission layers for the first user is 2 and the number of transmission layers for the second user is 3 in the example of FIG. 15b. Also, the new SE field (New extType) indicates that the number of ueIDs assigned to each user is 4 and 8, respectively. Assuming that ueIDs are assigned consecutively to each of the aforementioned users, the RU identifies that four consecutive ueIDs, i.e., ueIDs = 0, 1, 2, 3, have been assigned to the first user in the example of Figure 15b, and that eight consecutive ueIDs, i.e., ueIDs = 8, 9, 10, ... 15, have been assigned to the second user from representative ueID = 8.

[0113] According to the sixth operation 1500 described above with reference to Figures 15a and 15b, unlike other examples, by assuming consecutive ueIDs and setting ueIDs according to a different method from the existing methods, the transmission efficiency can be improved by not including explicit parameters indicating the total number of users and the number of transmission layers for each user but transmitting them implicitly. Also, the transmission efficiency can be improved by not explicitly including all the ueID values ​​assigned to each user but transmitting them implicitly via the representative ueID of each user and the number of ueIDs assigned to each user. The RU receives the information in the message format according to Figure 15a or 15b, and for the first user, 4 x N tA channel matrix (using ueID=0,1,2,3) is constructed and an 8×N t A channel matrix (using ueID = 8, 9, ..., 15) can be constructed. Once each user channel matrix is ​​constructed, it is possible to generate weights suited to each user by applying channel subspace decomposition, thereby improving the transmission efficiency of each user compared to ZF-based transmission.

[0114] (2) DU with W SU and X k If

[0115] If W SU and X k When the UEID is generated in the DU, in addition to the interface for transmitting the ueID group information and additional information described with reference to FIGS. 10 to 15 (FIGS. 15a and 15b), the W SU or X k An interface is needed to additionally convey

[0116] FIG. 16 is a diagram illustrating a message format for transmitting weights or channel transformation matrices according to an embodiment of the present invention.

[0117] Referring to Figure 16, the new SE SU or X k The format 1600 for transmitting the above is disclosed as an example. All other variables except zISample / zQSample and numAnt are the same as the previous definitions. The meaning of the numAnt and zSample values ​​changes depending on the wf (weight flag). If SU transmission is used, numAnt is the number of transmitting antennas, and the zSample value is N. t ×L W SU If it is MU transmission, numAnt means the number of receiving antennas for each user, and z sample value is L k ×N r,k X k Here, the z sample value is transmitted to all RB ranges set in ST5. SU and Xk is an example of supporting one format, but it can also be supported in two other formats.

[0118] FIG. 17 is a flow chart illustrating operation 1700 of a digital unit (DU) according to one embodiment of the present invention.

[0119] 17, in step 1702, the DU may determine scheduling-related parameters for at least one user. The scheduling-related parameters may include at least one ueID corresponding to each user and the number of ueIDs corresponding to each user. In addition, the number of users to be scheduled according to the scheduling information and the number of transmission layers for each user may be explicitly or implicitly determined according to the above-described embodiments. The scheduling-related parameters disclosed above are for illustrative purposes only and do not limit the scope of the present invention, and may include any parameters required for the DU to transmit scheduling information to a radio unit (RU).

[0120] In step 1704, the DU may transmit scheduling information including the scheduling-related parameters to the RU. According to one embodiment of the present invention, the scheduling information may include a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs corresponding to each user. According to one embodiment of the present invention, the first section extension field may include the same ueID for each of the at least one user, repeated as many times as the number of layers of the user. According to one embodiment of the present invention, the first section extension field may include different ueIDs as many times as the number of the at least one users scheduled via the scheduling information. According to one embodiment of the present invention, the at least one ueID corresponding to each user may have consecutive values ​​as many as the number of ueIDs corresponding to the user.

[0121] FIG. 18 is a flow chart illustrating operation 1800 of a radio unit (RU) according to one embodiment of the present invention.

[0122] Referring to FIG. 18, in step 1802, an RU may receive scheduling information including scheduling-related parameters for at least one user from a digital unit (DU). According to one embodiment of the present invention, the scheduling information may include a first section extension field including information on user equipment identifiers (ueIDs) for the at least one user and a second section extension field including information on the number of ueIDs corresponding to each user. According to one embodiment of the present invention, the first section extension field may include the same ueID for each of the at least one user, repeated as many times as the number of layers of the user. According to one embodiment of the present invention, the first section extension field may include different ueIDs as many times as the number of the at least one users scheduled via the scheduling information. According to one embodiment of the present invention, the at least one ueID corresponding to each user may have consecutive values ​​as many as the number of ueIDs corresponding to the user.

[0123] In step 1804, the RU may acquire the scheduling-related parameters based on the scheduling information. The scheduling-related parameters may include at least one ueID corresponding to each user and the number of ueIDs corresponding to each user. In addition, the number of users to be scheduled according to the scheduling information and the number of transmission layers for each user may be explicitly or implicitly determined according to the above-described embodiments. The scheduling-related parameters disclosed above are for illustrative purposes only and do not limit the scope of the present invention, and may include any parameters required for a DU to transmit scheduling information to a radio unit (RU).

[0124] FIG. 19 is a diagram showing the structure of a DU and an RU according to one embodiment of the present invention.

[0125] 19, base station RU apparatus 1900 includes a transceiver 1910, a controller 1920, a connector 1930, and a memory 1940. However, the components of base station RU apparatus 1900 are not limited to the above example, and for example, base station RU apparatus 1900 may include more or fewer components than those shown. In addition, transceiver 1910, memory 1940, and controller 1920 may be implemented in the form of a single chip.

[0126] The transceiver 1910 can transmit and receive signals to and from a terminal. Here, the signals can include control information and data. To this end, the transceiver 1910 can include an RF transmitter that up-converts and amplifies the frequency of a signal to be transmitted, an RF receiver that low-noise amplifies the received signal, and down-converts the frequency. However, this is only one embodiment of the transceiver 1910, and the components of the transceiver 1910 are not limited to an RF transmitter and an RF receiver. Furthermore, the transceiver 1910 can receive signals via a wireless channel, output them to the controller 1920, and transmit the signals output from the controller 1920 via a wireless channel. Furthermore, the transceiver 1910 can include separate RF transceivers for the LTE system and NR system, or can perform physical layer processing for both LTE and NR using a single transceiver.

[0127] The memory unit 1940 can store programs and data necessary for the operation of the base station's RU device. The memory unit 1940 can also store control information or data included in signals transmitted and received by the base station's RU device. The memory unit 1940 can be configured as a storage medium such as a ROM (Read Only Memory), RAM, hard disk, CD-ROM, DVD, etc., or a combination of storage media. The memory unit 1940 can also be multiple.

[0128] The controller 1920 can control a series of processes to operate the base station RU device 1900 according to the above-described embodiment of the present disclosure. For example, the controller 1920 can transmit and receive LTE or NR signals to and from the UE using C-plane messages and U-plane messages received from the base station DU device 1950 via the connector 1930. There may be multiple controllers 1920, and the controllers 1920 can control the component operations of the base station RU device 1900 by executing programs stored in the memory unit 1940.

[0129] The connector 1930 is a device that connects the base station RU device 1900 and the base station DU device 1950, and is capable of performing physical layer processing for message transmission and reception, as well as sending messages to the base station DU device 1950 and receiving messages from the base station DU device 1950.

[0130] The base station DU device 1950 includes a control unit 1970, a connector 1960, and a memory unit 1980. However, the components of the base station DU device 1950 are not limited to the above example, and for example, the base station DU device 1950 may include more or fewer components than those shown in the figure. In addition, the connector 1960, memory unit 1980, and control unit 1970 may be embodied in the form of a single chip.

[0131] The controller 1960 can control a series of processes to operate the base station DU device 1950 according to the above-described embodiment of the present disclosure. For example, the controller 1960 can generate C-plane messages and U-plane messages to be sent by the base station RU device 1900 and transmit the messages to the base station RU device 1900 via the connector 1960. There may be multiple controllers 1960, and the controllers 1960 can control the component operations of the base station DU device 1950 by executing programs stored in the memory unit 1980.

[0132] The memory unit 1940 can store programs and data necessary for the operation of the base station's RU device. The memory unit 1940 can also store control information or data included in signals transmitted and received by the base station's RU device. The memory unit 1940 can be configured as a storage medium such as a ROM (Read Only Memory), RAM, hard disk, CD-ROM, DVD, etc., or a combination of storage media. The memory unit 1940 can also be multiple.

[0133] The connector 1960 is a device that connects the base station RU device 1900 and the base station DU device 1950, and is capable of performing physical layer processing for message transmission and reception, as well as transmitting messages to the base station RU device 1900 and receiving messages from the base station RU device 1900.

[0134] In the specific embodiments of the present disclosure described above, elements included in the present invention are expressed in singular or plural form according to the specific embodiments presented. However, the expressions singular or plural are selected to fit the presented situation for the convenience of explanation, and the present disclosure is not limited to singular or plural elements, and elements expressed in plural form may be composed in singular form, and elements expressed in singular form may be composed in plural form.

[0135] While the present disclosure has been shown and described with reference to various embodiments, it will be apparent to those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and equivalents. [Explanation of symbols]

[0136] 100 O-RAN gNB 110 NRT-RIC 120 RIC 130 O-CU-CP 140 O-CU-UP 150 O-DU 160 O-RU 1900 Radio Unit (RU) Equipment 1910 Transmitter / Receiver 1920 Control Unit 1930 Connector 1940 Memory section 1950 Digital Unit (DU) device 1960 Connector 1970 Control Unit 1980 Memory Department

Claims

1. 1. A method in a distributed unit (DU) of a base station, comprising: determining scheduling-related parameters for the users by identifying one or more user equipment identifiers (ueIDs) corresponding to each user and the number of ueIDs corresponding to each user; transmitting scheduling information including the scheduling-related parameters to a radio unit (RU); The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field including information related to the number of ueIDs corresponding to each user; The method, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

2. The method of claim 1 , wherein the one or more ueIDs corresponding to each user have consecutive values ​​equal to the number of ueIDs corresponding to each user.

3. 2. The method of claim 1, wherein the first section extension field provides the number of layers for each user.

4. 4. The method of claim 3, wherein for each user, the first section extension field contains the same ueID repeated for each layer of the user.

5. A distributed unit (DU) device of a base station, comprising: a coupling configured to transmit and receive signals to and from a radio unit (RU); and at least one control unit, wherein the control unit: determining scheduling-related parameters for the users by identifying one or more user equipment identifiers (ueIDs) corresponding to each user and the number of ueIDs corresponding to each user; configured to transmit scheduling information including the scheduling-related parameters to the RU; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field including information related to the number of ueIDs corresponding to each user; The apparatus, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

6. The device according to claim 5 , wherein the one or more ueIDs corresponding to each user have consecutive values ​​equal to the number of ueIDs corresponding to each user.

7. 6. The apparatus of claim 5, wherein the first section extension field provides the number of layers for each user.

8. 8. The apparatus of claim 7, wherein for each user, the first section extension field includes the same ueID repeated for each layer of the user.

9. 1. A method for a base station radio unit (RU), comprising: receiving scheduling information including scheduling-related parameters for users from a distributed unit (DU), the scheduling-related parameters including one or more user equipment identifiers (ueIDs) corresponding to each user and a number of ueIDs corresponding to each user; and obtaining scheduling-related parameters for the user based on the scheduling information; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field including information related to the number of ueIDs corresponding to each user; The method, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

10. The method of claim 9 , wherein the one or more ueIDs corresponding to each user have consecutive values ​​equal to the number of ueIDs corresponding to each user.

11. 10. The method of claim 9, wherein the first section extension field provides the number of layers for each user.

12. The method of claim 11 , wherein for each user, the first section extension field contains the same ueID repeated for each layer of the user.

13. A radio unit (RU) device of a base station, comprising: a coupling configured to send and receive signals to and from a distributed unit (DU); and at least one control unit, wherein the control unit: Receive scheduling information including scheduling-related parameters for users from the DU, where the scheduling-related parameters include one or more ueIDs (user equipment identifiers) corresponding to each user and the number of ueIDs corresponding to each user; configured to obtain scheduling-related parameters for the user based on the scheduling information; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field including information related to the number of ueIDs corresponding to each user; The apparatus, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

14. The device according to claim 13 , wherein the one or more ueIDs corresponding to each user have consecutive values ​​equal to the number of ueIDs corresponding to each user.

15. 14. The apparatus of claim 13, wherein the first section extension field provides the number of layers for each user.

16. 16. The apparatus of claim 15, wherein for each user, the first section extension field includes the same ueID repeated for each layer of the user.

17. 1. A method in a distributed unit (DU) of a base station, comprising: determining scheduling-related parameters for each user by identifying one or more ueIDs (user equipment identifiers) corresponding to each user and a numUeID (number of ueIDs per user) corresponding to each user; transmitting scheduling information including the scheduling-related parameters to a radio unit (RU); The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field containing information related to numUeID corresponding to each user; The method, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

18. A distributed unit (DU) device of a base station, comprising: a coupling configured to transmit and receive signals to and from a radio unit (RU); and at least one control unit, wherein the control unit: Determine scheduling-related parameters for each user by identifying one or more ueIDs (user equipment identifiers) corresponding to each user and numUeIDs (number of ueIDs per user) corresponding to each user; configured to transmit scheduling information including the scheduling-related parameters to the RU; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field containing information related to numUeID corresponding to each user; The apparatus, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

19. 1. A method for a base station radio unit (RU), comprising: receiving scheduling information including scheduling-related parameters for users from a distributed unit (DU), the scheduling-related parameters including one or more ueIDs (user equipment identifiers) corresponding to each user and numUeIDs (number of ueIDs per user) corresponding to each user; and obtaining scheduling-related parameters for the user based on the scheduling information; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field containing information related to numUeID corresponding to each user; The method, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

20. A radio unit (RU) device of a base station, comprising: a coupling configured to send and receive signals to and from a distributed unit (DU); and at least one control unit, wherein the control unit: Receive scheduling information including scheduling-related parameters for users from the DU, where the scheduling-related parameters include one or more ueIDs (user equipment identifiers) corresponding to each user and numUeIDs (number of ueIDs per user) corresponding to each user; configured to obtain scheduling-related parameters for the user based on the scheduling information; The scheduling information a first section extension field containing information related to one or more ueIDs corresponding to each user; a second section extension field containing information related to numUeID corresponding to each user; The apparatus, wherein the first section extension field includes different ueIDs equal to the number of users scheduled through the scheduling information.

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