Singular value decomposition (SVD)-based port combining signaling method and device in communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for providing a higher data transmission rate than a 4G communication system, such as LTE. In addition, the present disclosure relates to a method performed by a remote unit (RU) in a wireless communication system, comprising the steps of: receiving a port combining configuration from a digital unit (DU); determining whether to perform singular value decomposition (SVD) port combining on the basis of the port combining configuration; transmitting an indication indicating the SVD port combining to the DU when the SVD port combining is performed; and transmitting, to the DU, a signal to which the SVD port combining is applied, wherein the indication is used to decode the signal.

Description

SVD (SINGULAR VALUE DECOMPOSITION)-based PORT COMBINING SIGNALING METHOD AND DEVICE IN A COMMUNICATION SYSTEM

[0001] The present disclosure relates to the operation of a terminal and a base station in a wireless communication system. More specifically, the present disclosure relates to a method and device for a terminal and a base station for port combining signaling for an Open RAN Digital Unit (DU) in a wireless communication system using SVD.

[0002] Looking back at the evolution of wireless communication over successive generations, technologies have primarily been developed for human-facing services such as voice, multimedia, and data. With the commercialization of 5G (5th-generation) communication systems, an explosive increase in connected devices is expected to be connected to communication networks. Examples of networked objects include vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction equipment, and factory equipment. Mobile devices are expected to evolve into diverse form factors, including augmented reality glasses, virtual reality headsets, and holographic devices. In the 6th-generation (6G) era, efforts are being made to develop improved 6G communication systems to connect hundreds of billions of devices and objects and provide diverse services. For this reason, 6G communication systems are often referred to as "Beyond 5G" systems.

[0003] The 6G communication system, expected to be realized around 2030, will have a maximum transmission speed of terabytes per second (i.e., 1,000 gigabits per second) and a wireless latency of 100 microseconds (μsec). In other words, compared to 5G, the transmission speed in a 6G communication system will be 50 times faster, while the wireless latency will be reduced to one-tenth.

[0004] To achieve these high data rates and ultra-low latency, 6G communication systems are being considered for implementation in the terahertz band (e.g., from 95 gigahertz (GHz) to 3 terahertz (THz)). Compared to the millimeter wave (mmWave) band introduced in 5G, the terahertz band is expected to experience more severe path loss and atmospheric absorption, making it more crucial to ensure signal reach, or coverage, in this band. Key technologies to ensure coverage include radio frequency (RF) components, antennas, new waveforms that offer better coverage than orthogonal frequency division multiplexing (OFDM), beamforming, and multiple antenna transmission technologies such as massive multiple-input and multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas. In addition, new technologies such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing using orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS) are being discussed to improve the coverage of terahertz band signals.

[0005] In addition, in order to improve frequency efficiency and system network, 6G communication systems are developing full duplex technology that utilizes the same frequency resources for uplink and downlink at the same time; network technology that integrates satellites and high-altitude platform stations (HAPS); network structure innovation technology that supports mobile base stations and enables optimization and automation of network operation; dynamic spectrum sharing technology through collision avoidance based on spectrum usage prediction; AI-based communication technology that utilizes artificial intelligence (AI) from the design stage and internalizes end-to-end AI support functions to realize system optimization; and next-generation distributed computing technology that realizes services with complexity that exceeds the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources (mobile edge computing (MEC), cloud, etc.). In addition, efforts are being made to further strengthen connectivity between devices, further optimize networks, promote softwareization of network entities, and increase the openness of wireless communications through the design of new protocols to be used in 6G communication systems, the implementation of hardware-based security environments, the development of mechanisms for the safe use of data, and the development of technologies for maintaining privacy.

[0006] Research and development of these 6G communication systems are expected to enable a new level of hyper-connected experience through the hyper-connectivity of 6G communication systems, which encompass not only connections between things but also connections between people and things. Specifically, 6G communication systems are expected to enable services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, services such as remote surgery, industrial automation, and emergency response, which are provided through 6G communication systems through enhanced security and reliability, will be applied in diverse fields such as industry, medicine, automobiles, and home appliances.

[0007] The present disclosure provides a method and device capable of effectively providing services in a wireless communication system. The present disclosure provides a method and device capable of improving communication performance and front-haul (FH) resource utilization efficiency in a wireless communication system by indicating the port combining method used by an RU in an O-RAN to a DU.

[0008] The technical problems to be achieved in the embodiments of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0009] In a method performed by a Remote Unit (RU) in a wireless communication system according to one embodiment of the present disclosure, the method includes the steps of: receiving a port combining configuration from a Digital Unit (DU); checking whether to perform SVD (Singular Value Decomposition) port combining based on the port combining configuration; transmitting an indication indicating the SVD port combining to the DU when the SVD port combining is performed; and transmitting a signal to which the SVD port combining is applied to the DU, wherein the indication may be characterized in that it is used to decode the signal.

[0010] In a method performed by a DU (Digital Unit) in a wireless communication system according to one embodiment of the present disclosure, the method may be characterized by including the steps of: transmitting a port combining configuration to a RU (Remote Unit); receiving an indication from the RU indicating SVD (Singular Value Decomposition) port combining when SVD port combining confirmed based on the port combining configuration is performed; receiving a signal to which the SVD port combining is applied from the RU; and decoding the signal based on the indication.

[0011] In one embodiment of the present disclosure, a RU (Remote Unit) of a wireless communication system includes a transceiver and a control unit connected to the transceiver, wherein the control unit receives a port combining configuration from a DU (Digital Unit), determines whether to perform SVD (Singular Value Decomposition) port combining based on the port combining configuration, and, when performing the SVD port combining, transmits an indication indicating the SVD port combining to the DU, and transmits a signal to which the SVD port combining is applied to the DU, and the indication may be characterized in that it is used to decode the signal.

[0012] In one embodiment of the present disclosure, a DU (Digital Unit) of a wireless communication system includes a transceiver and a control unit connected to the transceiver, wherein the control unit transmits a port combining configuration to a RU (Remote Unit), and when SVD (Singular Value Decomposition) port combining confirmed based on the port combining configuration is performed, receives an indication indicating the SVD port combining from the RU, receives a signal to which the SVD port combining is applied from the DU, and decodes the signal based on the indication.

[0013] The present disclosure provides a method and device for effectively performing wireless communication system services more appropriately in a 6G environment by having an RU indicate to a DU port combining used in a data transmission and reception process between an RU and a DU in an O-RAN network environment.

[0014] The effects that can be obtained from the present disclosure are not limited to the effects mentioned in the various embodiments, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0015] Figure 1 is a diagram illustrating the architecture of O-RAN.

[0016] Figure 2 is a diagram illustrating a wireless communication system using MIMO technology.

[0017] Figure 3 is a diagram illustrating a method of using the MRC Port combining method.

[0018] Figure 4 is a diagram illustrating a process of performing SVD-based port combining between RU and DU.

[0019] Figure 5 is a diagram illustrating the matrix inversion process in DU.

[0020] Figure 6 is a diagram illustrating a low-complexity matrix inversion process in DU.

[0021] FIG. 7 is a diagram illustrating a process for performing port combining between an RU and a DU according to one embodiment of the present disclosure.

[0022] FIG. 8 is a diagram illustrating a port combining signaling process of an RU according to an embodiment of the present disclosure.

[0023] FIG. 9 is a diagram illustrating a port combining signaling process of a DU according to an embodiment of the present disclosure.

[0024] FIG. 10 is a diagram illustrating devices of RU and DU in a wireless communication system according to an embodiment of the present disclosure.

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0026] In describing the embodiments, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to more clearly convey the gist of the present disclosure without obscuring it by omitting unnecessary explanations.

[0027] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect the actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0028] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to complete the configuration of the present disclosure and to fully inform those skilled in the art of the present disclosure of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification. In addition, when describing the present disclosure, if a specific description of a related function or configuration is determined to unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions of the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout the specification.

[0029] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, the embodiments of the present disclosure may also be applied to other communication systems having a similar technical background or channel type. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included here, and the 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications within a scope that does not significantly deviate from the scope of the present disclosure, as judged by a person having skilled technical knowledge.

[0030] At this time, it will be understood that each block of the processing flow diagrams and combinations of the flow diagrams can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flow diagram block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can be directed to a computer or other programmable data processing equipment for implementation in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flow diagram block(s). Since the computer program instructions can also be installed on a computer or other programmable data processing device, a series of operational steps can be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) can also provide steps for performing the functions described in the flowchart block(s).

[0031] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0032] Here, the term '~ unit' used in the present embodiment means software or hardware components such as FPGA (field programmable gate array) or ASIC (application-specific integrated circuit), and the '~ unit' performs certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium, and may be configured to play one or more processors. Accordingly, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units', or further separated into additional components and '~ units'. In addition, the components and '~parts' may be implemented to play one or more central processing units (CPUs) within the device or secure multimedia card. In addition, in the embodiment, the '~parts' may include one or more processors. Hereinafter, a / b may be understood as at least one of a or b.

[0033] Furthermore, while various embodiments of the present disclosure are described below using LTE, LTE-A, NR, or 6G-based systems as examples, the various embodiments of the present disclosure may also be applied to other communication systems with similar technical backgrounds or channel configurations. Furthermore, the various embodiments of the present disclosure may be applied to other communication systems with some modifications within the scope of the present disclosure, as determined by a person skilled in the art.

[0034] For the convenience of the following description, some terms and names defined in the 3rd generation partnership project (3GPP) standards (standards for 5G, NR, LTE, or similar systems) may be used. In addition, terms and names newly defined in next-generation communication systems (e.g., 6G, Beyond 5G systems) to which the present disclosure may be applied, or terms and names used in existing communication systems may be used. The use of such terms is not limited to the terms and names of the present disclosure, and may be equally applied to systems conforming to other standards, and may be modified into other forms without departing from the technical spirit of the present disclosure. Embodiments of the present disclosure may be easily modified and applied to other communication systems.

[0035] Wireless communication technology has made significant advancements in recent years, offering faster data rates, improved coverage, and more stable connections. However, as demand for wireless communication services continues to grow, many challenges remain, including network congestion, signal interference, and dynamic changes in network conditions.

[0036] The present invention relates to an O-RAN (Open-RAN) system, and to a signaling method and device that enables a RU to improve communication performance and FH resource utilization efficiency by using SVD-based port combining during a transmission and reception process between a radio signal processing unit (Remote Unit, hereinafter RU) in an O-RAN and a digital data processing unit (Digital Unit, hereinafter DU) in an O-RAN.

[0037] Hereinafter, the RU and DU in this disclosure assume RU and DU within an O-RAN network. Depending on the situation, RU may be understood as O-RU, and DU may be understood as O-DU. However, the network of the present invention is not limited to O-RAN, and the present invention can also be applied to other networks where RU and DU are included.

[0038] Figure 1 is a diagram illustrating the architecture of O-RAN.

[0039] According to Fig. 1, the O-RAN network is a standard that logically separates the eNB and gNB functions of existing 4G and 5G systems. In the O-RAN standard, NRT-RIC (110), RIC (120) within O-RAN gNB (100), CU-CP (130), CU-UP (140), DU (150), and RU (160) are defined.

[0040] NRT-RIC (110) is a logical node that enables non-real-time control and optimization of RAN elements and resources, model training and updates, etc. The newly defined RIC (120) is a logical node that enables near-real-time control and optimization of RAN elements and resources based on data collected from DU (150), CU-CP (130), CU-UP (140), etc. via the E2 interface by centrally deploying servers in one physical location. The CU, including CU-CP (130) and CU-UP (140), is a logical node that provides functions of radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocols. The CU-CP (130) is a logical node that provides functions of the control plane part of RRC and PDCP, and the CU-UP (140) is a logical node that provides functions of the user plane part of SDAP and PDCP. The CU-CP (130) is connected to the AMF (access and mobility management function) included in the 5G network (5G core) via an NGAP interface. The DU (150) is a logical node that provides RLC, MAC, and high-PHY functions, and the RU (160) connected to the 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, each logical node may be connected in multiple numbers. For example, multiple RUs (160) may be connected to one DU (150), and multiple DUs (150) may be connected to one CU-UP (140).

[0041] The present invention is not limited by the names of each node described above, and the configuration of the present invention can be applied to logical nodes or entities that perform the functions described above. In addition, the logical nodes can be physically located in the same location or different locations, and their functions can be provided by the same physical device (e.g., a processor, a control unit, etc.) or by different physical devices. For example, the functions of at least one logical node described above can be provided through virtualization in a single physical device. Hereinafter, DU can be used interchangeably with O-DU, and RU can be used interchangeably with O-RU.

[0042] FIG. 2 is a diagram illustrating a wireless communication system using MIMO technology.

[0043] The use of MIMO (Multiple Input Multiple Output) technology in wireless communication systems can increase the number of antennas used. Referring to Figure 2, UEs 1, 2, ..., and UE K can transmit and receive signals using MIMO. The information that the UEs wish to transmit to the RU may be, for example, s (210).

[0044] The corresponding information can be multiplied by the P value corresponding to the precoder. The signal generated at this time, for example, Ps (220), may be a signal transmitted from each antenna port of the terminal. Here, the dimension of the generated signal Ps may be N_TX by N_L. N_TX may represent the number of antenna ports, and N_L may represent the number of layers.

[0045] The base station's RU can receive signals using the receiving antenna ports. At this time, the received signal can be expressed as y=HPs+n (230). Here, H can be a passing channel, and the dimension of H can be N_RX by N_TX. N_RX can mean the number of receiving antenna ports of the RU.

[0046] The RU of the base station can transmit a signal (y' (240)) to the DU using the front-haul (FH), which is a link (or interface) connecting the RU and the DU. Specifically, y' can be the result of y multiplied by the F^H value. Here, the dimension of F^H can be N_C by N_RX. N_C can be the number of antenna ports transmitting from the RU to the DU. N_C can be less than or equal to N_RX.

[0047] In this way, as the number of antennas used increases with the use of MIMO, the amount of data transmitted from the RU to the DU may increase.

[0048] As the amount of data transmitted from RU to DU via FH increases, the amount of data required for FH may increase, and the present invention provides a method for solving this.

[0049] Specifically, to address the issue of excessive FH capacity requirements, port combining can be used to efficiently utilize FH resources. Port combining can refer to a method for reducing the number of data streams transmitted between the RU and the DU. For example, if it is determined that there is no significant loss in the data to be transmitted, some data streams can be transmitted instead of all data streams corresponding to the number of RU reception antennas. If the number of data streams transmitted from the RU to the DU is reduced through port combining, the capacity of data transmitted via the FH can be reduced.

[0050] As an example of a method for applying port combining, the MRC (Maximum Ratio Combining) method can be used.

[0051] Figure 3 is a diagram illustrating a method of using the MRC Port combining method.

[0052] Specifically, the MRC Port Combining method can perform combining by multiplying the received signals received through different antenna ports by a weight value that assigns a signal-to-noise ratio (SNR) weight, and adding the received signals multiplied by the weight value to maximize the SNR of the entire combined signal.

[0053] In addition, DFT-based port combining can be considered as another method of port combining. To perform DFT-based port combining, a projection matrix can be used. Specifically, the RU can determine the projection matrix based on the codebook, and transmit the signal and DMRS symbol with the projection matrix applied to the signal received from the terminal to the DU. The DU can calculate, generate, and apply the combiner matrix using the DMRS symbol. In this case, since DFT-based port combining determines the projection matrix based on the codebook, the port combining weight can be determined from a pre-defined set.

[0054] When port combining is used in an environment that uses only a single layer, it may be common to use the MRC port combining method. Meanwhile, current communication systems may support multi-layer uplink operations. As environments such as X-MIMO are gradually established, terminals that support multi-layer uplink may become widespread. However, while applying SVD-based port combining in an environment that uses multi-layer uplink offers significant performance gains, there is a problem of high computational complexity. Therefore, the present disclosure proposes a method for efficiently performing SVD-based port combining.

[0055] Figure 4 is a diagram illustrating a process of performing port combining between RU and DU.

[0056] According to FIG. 4, at step 410, the RU can receive a signal (y).

[0057] Additionally, RU can obtain H through channel estimation (CE). Here, H is a channel matrix and can reflect changes that occur while a signal passes through a channel in a wireless communication environment.

[0058] The RU can perform SVD-based port combining on the received signal. Specifically, the RU can obtain a weight for SVD-based port combining and perform SVD-based port combining based on the weight. The weight for SVD-based port combining can be obtained according to the following mathematical expression 1.

[0059] [Mathematical Formula 1]

[0060]

[0061] When performing SVD on the channel matrix H, can be decomposed into. Here, the U matrix obtained through SVD, or a value determined based on the U matrix, can be used as a weight value (F) in SVD-based port combining. The U matrix can be defined as a value or matrix on which SVD is performed for a channel. The signal y' obtained through port combining (e.g., RX port combining) can be obtained by multiplying the received signal y by F corresponding to the port combining filter value according to the following mathematical expression 2.

[0062] [Equation 2]

[0063]

[0064] The RU can transmit y' corresponding to the combined signal in step 420 to the DU.

[0065] The DU that receives y can estimate the original signal y through the detector. The estimated signal The DU that has acquired the signal can transmit the signal to the network.

[0066] When using SVD-based port combining, the F value can be determined to satisfy the mathematical expression 3 below.

[0067] [Equation 3]

[0068]

[0069] The above mathematical expression 3 indicates that the F value can be determined in a direction that maximizes the SNIR, and does not indicate the F value itself. By determining the F value in this way in a direction that maximizes the SNIR, channel capacity can be maximized. However, as described above, there is a problem in that the computational complexity is high when using SVD-based port combining. Therefore, the present disclosure proposes a method for efficiently performing SVD-based port combining.

[0070] Figure 5 is a diagram illustrating the matrix inversion process in DU.

[0071] The RU can receive a signal (y), perform port combining on the received signal, and transmit y' to the DU. The specific details are the same as in Fig. 4, and are therefore omitted below.

[0072] As shown in Fig. 4, DU receives y' and estimates the signal through a specific process. can be obtained and transmitted to a network entity. In Fig. 5, the signal estimated through a detection operation including matrix inversion in the DU that received y' The process of obtaining is illustrated. Here, the matrix inversion process may include a process of performing forward and backward substitution through Cholesky Decomposition. However, the matrix inversion process as shown in Fig. 5 has the problem that the computation is very complex.

[0073] Figure 6 is a diagram illustrating a low-complexity matrix inversion process in DU.

[0074] When using the SVD-based port combining method, there is a problem of high computational complexity compared to using a typical matrix inversion. However, when using SVD-based port combining, low-complexity matrix inversion can be performed through a process similar to that shown in Figure 6.

[0075] Specifically, DU uses matrix inversion to The value can be determined. That is, low-complexity channel matrix inversion can be performed during the process of performing zero-forcing (ZF) operation or Interference Rejection Combining (IRC) operation.

[0076] can be obtained according to the mathematical formula 4 below.

[0077] [Equation 4]

[0078]

[0079] Specifically, the RU can perform SVD on the estimated channel H. The transpose matrix of the left singular vector matrix U obtained as a result can be applied as a port combining weight. The RU can transmit y', which is the value obtained by multiplying the received signal y by the port combining filter, to the DU. The DU that receives y' can perform channel estimation on the received value. The corresponding estimated result value Is It could be. Here Therefore, the corresponding value is can be expressed as . Since V is a unitary matrix, the inverse matrix and the hermitian matrix are the same. The relationship can be established. Diagonal singular value matrix Is together And that Hermitian matrix It can be confirmed through the multiplication operation. At this time, in the case of a diagonal matrix, the division is performed as many times as the number of diagonal elements for the inverse matrix operation, so the required amount of calculation can be very small. In other words, without using the Cholesky Decomposition and forward / backward substitution operations used to obtain the existing inverse matrix, it is obtained by CE. Hermitian operations and diagonal matrices Only the inverse matrix operation can be performed. As a result, low-complexity channel matrix inversion can be performed in the case of SVD-based port combining.

[0080] The meaning of each variable is as follows.

[0081] - : Channel matrix multiplied by Port Combining weight

[0082] - U left singular vector matrix

[0083] - : Diagonal singular value matrix

[0084] - V right singular vector matrix

[0085] In order to utilize low-complexity matrix inversion, the DU must be able to know the port combining method used by the RU. If the DU does not know the port combining method used by the RU, it cannot determine whether the low-complexity matrix inversion process can be utilized in the DU. If the DU does not know the port combining method used by the RU, the DU performs a matrix inversion process with high computational complexity rather than low-complexity matrix inversion.

[0086] According to the current O-RAN standard, there is no indication of a port combining method in an RU. Therefore, the present disclosure proposes a method for indicating to a DU the port combining method used in an RU.

[0087] In addition, the singular values ​​(hereinafter referred to as "singular values") calculated during the SVD process in the RU can be transmitted to the DU. When the singular values ​​are transmitted to the DU, the computation for obtaining the diagonal singular value matrix in the DU can be omitted, thereby reducing the computational complexity in the DU. Therefore, the present disclosure proposes a method for transmitting singular values ​​from the RU to the DU.

[0088] FIG. 7 is a diagram illustrating a process of port combining signaling between an RU and a DU according to one embodiment of the present disclosure.

[0089] According to FIG. 7, at step 710, the DU may send a capability request message related to port combining to the RU.

[0090] In response to the capability request message at step 720, the RU may send a capability information message to the DU. The capability information message may include capability information related to RU port combining.

[0091] The capability request message can be sent from the RU not only during the initial connection between the RU and the DU, but also at a later stage after the initial connection. Furthermore, the capability information message can be sent from the DU to the RU not only during the initial connection between the RU and the DU, but also at a later stage after the initial connection.

[0092] At step 730, the DU may transmit a configuration related to port combining to the RU. Furthermore, the RU may transmit a configuration related to port combining to the DU. The configuration may include port combining parameters set based on capability information. The port combining parameters may be used to indicate port combining.

[0093] An RU that receives a parameter can apply the parameter immediately upon receipt. Alternatively, it can apply the parameter at a time designated by the DU. In this case, the DU can transmit information about the application time and whether to apply it to the RU through port combining enable. Alternatively, the RU can determine the application time and whether to apply it on its own.

[0094] At step 740, the DU may transmit a port combining enabling signal to the RU. The port combining enabling signal may enable or disable the port combining configuration in the RU depending on whether port combining is applicable. The port combining enabling signal may also include whether a parameter included in the configuration has been applied.

[0095] For example, the DU can turn on the enable signal in case of single-user scheduling and turn it off in case of multi-user scheduling, considering the SVD capability of the RU. In this case, in case of single-user scheduling, the enable signal can be transmitted so that SVD port combining is performed only on specific resources depending on the SVD performance capability of the RU.

[0096] This step is optional, and the port combining enabling signal can be included and transmitted and received in the process of transmitting and receiving the port combining configuration without this step.

[0097] In step 750, the RU can transmit a port combining indication signal to the DU. The RU can perform port combining by applying the configuration set by the DU and then inform the DU of whether or not to perform port combining through the port combining indication signal. Alternatively, the RU can transmit an indication signal as an ACK (Acknowledgement) or NACK (Negative Acknowledgement) for a resource specified by the DU. Alternatively, the RU can transmit an indication signal regarding whether or not to apply SVD port combining in response to the DU's port combining enabling signal. Alternatively, even if there is no request from the DU, the RU can determine on its own to apply SVD port combining and then transmit an indication signal indicating whether or not to apply it.

[0098] The above indication may be composed of bits indicating whether a port combining configuration has been applied. The indication may be transmitted by being additionally included in a predefined message transmitted from the RU to the DU, or a separate message may be defined for the indication. Alternatively, the indication may indicate whether SVD has been applied using the Port Combining configuration proposed below. Alternatively, although the present disclosure exemplifies a method of transmitting an indication from the RU to the DU, a method of transmitting an indication from the DU to the RU may also be used when a signal to which SVD has been applied is transmitted from the DU to the RU. In addition, the step of transmitting the indication may be performed selectively.

[0099] At step 760, the RU may transmit a signal to the DU. The signal may be a signal to which SVD port combining has been applied. The signal may correspond to a message containing I / Q data.

[0100] If the RU uses the SVD-based port combining method at step 770, it can transmit a singular value to the DU. When transmitting a singular value to the DU, the amount of computation required to calculate the singular value in the DU can be reduced, thereby reducing computational complexity.

[0101] If a singular value is not received, the DU can perform the matrix inversion process of FIG. 6 described above. Specifically, the DU can determine the square of the singular value for the channel H obtained by the Channel Estimator through the H*hermitian(H) operation. Specifically, the singular value can correspond to the diagonal element value of Σ corresponding to the diagonal singular value matrix.

[0102] In contrast, a DU that receives a singular value from an RU can use the singular value, and thus can avoid performing the operation of finding the square value of the diagonal singular value matrix Σ through the H*hermitian(H) operation. In other words, when a DU receives a singular value, the amount of computation can be reduced.

[0103] This step is optional, and the DU can send a singular value request value to the RU during the process of transmitting and receiving port combining configuration without this step.

[0104] In the following embodiments, a method for transmitting and receiving port combining capability between RU and DU is proposed to perform port combining.

[0105] [Example 1: Transmitting port combining capability via M-plane (Management-plane)]

[0106] According to one embodiment of the present disclosure, an RU may transmit a port combining capability to a DU. Specifically, the port combining capability message may be transmitted via the M-plane as shown in [Table 1] below. Specifically, it may be transmitted via o-ran-module-cap (e.g., o-ran-module-cap.yang.module) in the M-plane.

[0107]

[0108] Specifically, the capability information transmitted via o-ran-module-cap may include a port combining configuration. The port combining configuration may include supported port combining methods (e.g., method-of-port-combining). Alternatively, the port combining configuration may include information on whether the RU can perform port combining. The port combining method may include SVD-based port combining (e.g., svd-port-combining). When the SVD-based port combining method is used, at least one of the following may be included as a specific description of the port combining method: the maximum number of layers that can be supported (e.g., max-svd-layers), the number of SVD operation engines (e.g., number-of-svd-engines), and information indicating whether singular values ​​are transmitted. The information may be transmitted in the form of parameters.

[0109] Alternatively, according to one embodiment of the present disclosure, the RU may transmit a capability message containing capability information related to RU port combining to the DU. Specifically, the capability message may be transmitted in a manner as shown in [Table 2] below. The capability message may be conveyed as a subfield value of a field related to beamforming in the O-RAN M-plane.

[0110]

[0111] Specifically, the capability information transmitted via o-ran-module-cap may include a port combining configuration. The port combining configuration may include supported port combining methods (e.g., method-of-port-combining). Alternatively, the port combining configuration may include information on whether the RU can perform port combining. The port combining method may include SVD-based port combining (e.g., svd-port-combining). When the SVD-based port combining method is used, at least one of the following may be included as a specific description of the port combining method: the maximum number of layers that can be supported (e.g., max-svd-layers), the number of SVD operation engines (e.g., number-of-svd-engines), and information indicating whether singular values ​​are transmitted. The information may be transmitted in the form of parameters.

[0112] A capability message containing capability information related to RU Port Combining can be transmitted via the M-plane as shown in [Table 1] or [Table 2] above. However, the Capability Information transmission method is not limited to the above method and can be transmitted in other ways.

[0113] Capability information can be transmitted in a capability report message in response to the capability request message sent by the DU to the RU in step 710. The DU can receive the RU's port combining capability information during the initial connection process with the RU. Furthermore, the DU can also send a request message at a later stage after the initial connection. The RU can also receive capability information in response thereto.

[0114] In the following embodiments, a port combining configuration is proposed for transmitting to an RU that is transmitted and received between an RU and a DU to perform port combining. Furthermore, the present disclosure proposes the following information as a port combining configuration for transmitting from a DU to an RU or from an RU to a DU. The information below can be transmitted from an RU to a DU to indicate whether SVD port combining has been applied.

[0115] [Example 2: Transmitting port combining configuration via C-plane (Control plane) - Utilizing Section Extension of Section Type 1]

[0116] According to one embodiment of the present disclosure, the RU may transmit a configuration related to port combining to the DU. Furthermore, the RU may transmit a configuration related to port combining to the DU. Specifically, the configuration related to port combining (hereinafter, “port combining configuration”) may include at least one of the information included in the port combining capability information in Embodiment 1. The port combining configuration may be transmitted via the C-plane.

[0117] Port combining configuration can be set based on parameters defined for SVD-based port combining in Section Extensions of Section Type 1. Specifically, a new extension type (e.g., exType) can be added to Section Extensions, and the extension type can indicate SVD-based port combining (e.g., SVD Port Combing). The extension type indicating SVD-based port combining can indicate parameters related to SVD-based port combining.

[0118] [Table 3] below shows the existing Section Type 1: DL / UL control msgs.

[0119]

[0120] [Table 4] below shows a case where a new extension Type is added to the section extensions according to [Table 3] to indicate SVD (based) port combining, according to one embodiment of the present disclosure.

[0121]

[0122] If a new extension type is defined that directs SVD-based port combining, the port combining configuration may include the following section extension parameters:

[0123] In addition to the parameters mentioned in the embodiment of the M-plane (for example, at least one of the supportable port combining methods, information on whether the RU can perform port combining, the maximum number of supportable layers, the number of SVD operation engines, and information indicating whether a singular value is transmitted), the section extension parameter may include at least one of the following: the number of antenna ports of the RU (the antenna port may mean a logical antenna port), the number of reduced ports reduced in consideration of the front-haul capacity, the ratio of the number of antennas applied to port combining to the number of reduced ports, the port combining method used, whether port combining is applied, the value of the port combining weight (for example, the in-phase and quadrature phase values), whether compression of the port combining weight is applied, the value of the port combining weight after compression (for example, the in-phase and quadrature phase values), the compression bit-width of the port combining weight, the port combining application resource, the repetition indication indicating whether the configuration value is the same as the previous configuration to improve the field read speed and processing speed of the RU, the port combining weight extension, the port combining weight extension type, whether switching is applied, and the singular value.

[0124] The number of antenna ports of an RU can be defined, for example, as numLogicalAntPort, and can have values ​​such as 64, 128, 512, 1024. The number of reduced ports that are reduced considering the front-haul capacity can be defined, for example, as numReducedPort, and can have values ​​such as 4, 8, 16. The ratio of the number of antennas applied to port combining to the number of reduced ports can be defined, for example, as PortCombiningRatio, and can have values ​​such as 2:1, 4:1, 8:1, etc. The numReducedPort value can be replaced with the PortCombiningRatio value. The port combining method used can be defined, for example, as PortCombiningMethod, and can have values ​​such as MRC, SVD, DFT, none, etc. If the port combining method used is SVD, a low-complexity method can be used for the inverse matrix operation. The port combining weight can be defined, for example, as PortCombiningWeight. If the port combining weight is in-phase, it can be defined as, for example, pcwI, and if the port combining weight is quadrate phase, it can be defined as, for example, pcwQ. When the port combining weight is defined, it can be assumed that the corresponding value is calculated in the DU and the RU is transmitted. Whether or not to apply compression to the port combining weight can be defined as, for example, PortCombiningWeightCompression. If PortCombiningWeightCompression is defined, the same operation as weight compression in beamforming can be performed.When weight compression is performed, it can have values ​​such as pcwCompHdr, pcwCompParam, etc. or be defined as a parameter. A singular value can be defined, for example, as SingularValue. When a singular value is defined, it may be assumed that the singular value is transmitted in the RU instead of calculating the singular value in the DU. The port combining application resource can have values ​​such as PortCombiningRB, PortCombiningRE, PortCombiningSymb, etc. Each value may be intended to indicate which resource applies port combining. Repetition Indication can be defined, for example, as Repetition, and if the value is 0b, the previous setting is used as is, and the parameter is not read again, which can shorten the operation time. Switching can be defined as a value indicating whether the combining method is switched or not, and can be defined as Switching. When the Repetition value is 1 and the Switching value is also 1, only the port combining method is switched, so other parameters do not need to be read, which can shorten the computation time. In all other cases except when the Repetition value is 1 and the Switching value is also 1, it may be necessary to read all other fields.

[0125] To determine whether the port combining weight extension is used, for example, PortCombiningWeightExtension can be defined. If the PortCombiningWeightExtension value is 1, the extension can be used. To determine the type of the port combining weight extension, typePortCombiningWeightExtension can be defined, and can have values ​​such as orthogonal and partial orthogonal. Parameters related to the port combining weight extension and the type combining weight extension can be integrated into the port combining method parameter. At least one of the port combining weight, including the in-phase case and the quadrate phase case, whether to apply compression to the port combining weight, the value in case weight compression is performed (for example, at least one of pcwCompHdr, pcwCompParam), and the port combining application resource (for example, at least one of PortCombiningRB, PortCombiningRE, PortCombiningSymb), can be transmitted from the DU to the RU.

[0126] Among the parameters, singular values ​​can be transmitted from RU to DU.

[0127] At least one of the following parameters can be transmitted from the RU to the DU: the number of antenna ports corresponding to other parameters, the number of reduced ports considering the front-haul capacity, the ratio of the number of antennas applied to port combining and the number of reduced ports, the port combining method used, the repetition indication, and whether switching is enabled. In addition, at least one of the following parameters can be transmitted from the DU to the RU.

[0128] The configuration related to port combining can be transmitted from the DU to the RU in step 730. In addition, the configuration related to port combining can be transmitted from the RU to the DU in step 730.

[0129] In the following embodiments, a port combining configuration is proposed for transmitting to an RU that is transmitted and received between an RU and a DU to perform port combining. Furthermore, the present disclosure proposes the following information as a port combining configuration for transmitting from a DU to an RU or from an RU to a DU. The information below can be transmitted from an RU to a DU to indicate whether SVD port combining has been applied.

[0130] [Embodiment 3: Transmitting port combining configuration via C-plane - Utilizing dt4CmdType of Section Type 4] According to one embodiment of the present disclosure, an RU may transmit a configuration related to port combining to a DU. Furthermore, the RU may transmit a configuration related to port combining to the DU. Specifically, the port combining configuration may include at least one of the information included in the port combining capability information in Embodiment 1. The port combining configuration may be transmitted via the C-plane.

[0131] Port combining configuration can be set based on the parameters defined for SVD-based port combining in st4CmdType of Section Type 4. Here, st4CmdType can mean a parameter that specifies a unique command type value that specifies a slot level to be applied to a single or multiple IDs. Specifically, a new type (e.g., ST4CmdType) can be added to st4CmdType, and the type can indicate SVD-based port combining.

[0132] The type indicating the above SVD-based port combining may indicate parameters related to SVD-port combining. The parameters related to SVD-port combining may include a parameter that commands transmission of at least one of the SVD-based port combining related configuration and port combining weights.

[0133] [Table 5] below shows the existing Section Type 4: Command common header format.

[0134]

[0135] [Table 6] below shows a case in which, according to one embodiment of the present disclosure, when st4CmdType=1 according to [Table 5], a new command type is added to st4CmdType to indicate SVD-based port combining.

[0136] Referring to [Table 6] below, the port combining configuration can be set based on the parameters defined for SVD-based combining in st4CmdType of Section Type 4. Specifically, a new type (e.g., ST4CmdType) can be added to st4CmdType, and the type can indicate SVD-based combining. The type indicating SVD-based port combining can indicate parameters related to SVD-based port combining.

[0137] For example, referring to the table below, if the new field is set to 0000 0011b, SVD-based port combining can be indicated. If SVD-based port combining is indicated, transmission of port combining configuration and / or port combining weight can be indicated.

[0138]

[0139] [Table 7] below shows the port combining configuration when st4CmdType indicates SVD-based port combining. According to [Table 7] below, the port combining configuration may include at least one of PortCombiningType, at least one singular value (firstSingularValue, secondSingularValue, etc.), and a compression header.

[0140]

[0141] The configuration related to port combining can be transmitted from the DU to the RU in step 730. In addition, the configuration related to port combining can be transmitted from the RU to the DU in step 730.

[0142] In the following embodiments, a port combining configuration is proposed for transmitting to an RU that is transmitted and received between an RU and a DU to perform port combining. Furthermore, the present disclosure proposes the following information as a port combining configuration for transmitting from a DU to an RU or from an RU to a DU. The information below can be transmitted from an RU to a DU to indicate whether SVD port combining has been applied.

[0143] [Embodiment 4: Transmitting port combining configuration via C-plane or U-plane (User plane) - Utilizing udCompMeth of Section Type 1] According to one embodiment of the present disclosure, an RU may transmit a configuration related to port combining to a DU. Furthermore, the RU may transmit a configuration related to port combining to the DU. Specifically, the port combining configuration may include at least one of the information included in the port combining capability information in Embodiment 1. The port combining configuration may be transmitted via the C-plane or the U-plane.

[0144] [Table 8] below shows the existing Section Type 1: DL / UL I / Q data msgs.

[0145]

[0146] [Table 9] below shows a case where a new udCompMeth is added to udCompHdr according to [Table 8] to indicate SVD (based) port combining, according to one embodiment of the present disclosure.

[0147] Referring to [Table 9] below, the port combining configuration can be defined in udCompHdr of Section Type 1. Here, udCompHdr is provided to the U-plane and may mean information that instructs the RU and DU on how to interpret and decompress the received U-plane data. Specifically, a new method (e.g., udCompMeth) may be added to udCompHdr, and the method may indicate SVD-based port combining (e.g., SVD port combining). The method indicating the SVD-based port combining may indicate parameters related to the SVD-based port combining.

[0148] For example, referring to the table below, if the new field is set to 0111b, it can indicate SVD-based port combining (e.g., SVD Port Combining).

[0149]

[0150] The configuration related to port combining can be transmitted from the DU to the RU in step 730. In addition, the configuration related to port combining can be transmitted from the RU to the DU in step 730.

[0151] In the following embodiments, a port combining configuration is proposed for transmitting to an RU that is transmitted and received between an RU and a DU to perform port combining. Furthermore, the present disclosure proposes the following information as a port combining configuration for transmitting from a DU to an RU or from an RU to a DU. The information below can be transmitted from an RU to a DU to indicate whether SVD port combining has been applied.

[0152] [Example 5: Transmitting a port combining configuration via C-pane or U-plane - Utilizing ciCompHdr of Section Type 6]

[0153] According to one embodiment of the present disclosure, the RU may transmit a configuration related to port combining to the DU. Furthermore, the RU may transmit a configuration related to port combining to the DU. Specifically, the port combining configuration may include at least one of the information included in the port combining capability information in Embodiment 1. The port combining configuration may be transmitted via the C-plane or the U-plane.

[0154] [Table 10] below shows the existing Section Type 6: channel information frame format.

[0155]

[0156] [Table 11] below shows a case where a new ciCompMeth is added to ciCompHdr according to [Table 10] to indicate SVD (based) port combining, according to one embodiment of the present disclosure.

[0157] Referring to [Table 11] below, the port combining configuration can be defined in ciCompHdr of Section Type 1. Here, ciCompHdr is provided to the U-plane and may mean information that instructs the RU and DU on how to interpret and decompress the received U-plane data. Specifically, a new method (e.g., ciCompMeth) may be added to ciCompHdr, and the method may indicate SVD-based port combining (e.g., SVD port combining). The method indicating the SVD-based port combining may indicate parameters related to the SVD-based port combining.

[0158] For example, referring to the table below, if the new field is set to 0111b, it can indicate SVD-based port combining (e.g., SVD Port Combining).

[0159]

[0160] FIG. 8 is a diagram illustrating a port combining signaling process of an RU according to an embodiment of the present disclosure.

[0161] According to FIG. 8, at step 810, the RU may receive a capability request message related to port combining from the DU.

[0162] In response to the capability request message at step 820, the RU may send a capability information message to the DU. The capability information message may include capability information related to RU port combining.

[0163] An RU can receive capability request messages from a DU not only during the initial connection between the RU and the DU, but also during other processes. Furthermore, an RU can send capability information messages to a DU not only during the initial connection between the RU and the DU, but also during other processes.

[0164] At step 830, the RU may transmit a configuration related to port combining to the DU. Furthermore, the RU may receive a configuration related to port combining from the DU. The configuration may include port combining parameters set based on capability information. The port combining parameters may be used to indicate port combining.

[0165] An RU that receives a parameter can apply the parameter immediately upon receipt. Alternatively, it can apply the parameter at a time designated by the DU. In this case, the RU can receive information about the application time and whether to apply it from the DU through port combining enable. Alternatively, the RU can independently determine the application time and whether to apply it.

[0166] At step 840, the RU may receive a port combining enabling or port combining enable signal from the DU. The port combining enabling or port combining enable signal may enable or disable the port combining configuration in the RU depending on whether port combining is applicable. In addition, the port combining enabling or port combining enable signal may include whether a parameter included in the configuration has been applied.

[0167] For example, the DU can turn on the enable signal in the case of single-user scheduling and turn it off in the case of multi-user scheduling, considering the SVD capability of the RU. In this case, in the case of single-user scheduling, the RU can receive an enable signal that is set to perform SVD port combining only on specific resources according to the SVD performance capability.

[0168] This step is optional, and the port combining enabling or port combining enable signal can be included and transmitted and received in the process of transmitting and receiving the port combining configuration without this step.

[0169] In step 850, the RU can transmit a port combining indication signal to the DU. The RU can perform port combining by applying the configuration set by the DU and then inform the DU of whether or not it has been performed through the port combining indication signal. Alternatively, the RU can transmit an indication signal meaning ACK (Acknowledgement) or NACK (Negative Acknowledgement) for a resource specified by the DU. Alternatively, the RU can transmit an indication signal regarding whether or not to apply SVD port combining in response to the DU's port combining enabling or port combining enable signal. Alternatively, even if there is no request from the DU, the RU can determine on its own to apply SVD port combining and then transmit an indication signal indicating whether or not it has been applied.

[0170] The above indication may be composed of bits indicating whether a port combining configuration has been applied. The indication may be transmitted by being additionally included in a predefined message transmitted from the RU to the DU, or a separate message may be defined for the indication. Alternatively, the indication may indicate whether SVD has been applied using the Port Combining configuration proposed below. Alternatively, although the present disclosure exemplifies a method of transmitting an indication from the RU to the DU, a method of transmitting an indication from the DU to the RU may also be used when a signal to which SVD has been applied is transmitted from the DU to the RU. In addition, the step of transmitting the indication may be performed selectively.

[0171] At step 860, the RU may transmit a signal to the DU. The signal may be a signal to which SVD port combining has been applied. The signal may correspond to a message containing I / Q data.

[0172] If the RU uses the SVD-based port combining method at step 870, it can transmit a singular value to the DU. When transmitting a singular value to the DU, the amount of computation required to calculate the singular value in the DU can be reduced, thereby reducing computational complexity.

[0173] This step is optional, and the DU can send a singular value request value to the RU during the process of transmitting and receiving port combining configuration without this step.

[0174] FIG. 9 is a diagram illustrating a port combining signaling process of a DU according to an embodiment of the present disclosure.

[0175] According to FIG. 9, at step 910, the DU may send a capability request message related to port combining to the RU.

[0176] In response to the capability request message at step 920, the DU may receive a capability information message from the RU. The capability information message may include capability information related to RU port combining.

[0177] A DU can send capability request messages to an RU not only during the initial connection between the RU and the DU, but also during other processes. Furthermore, a DU can receive capability information messages from an RU not only during the initial connection between the RU and the DU, but also during other processes.

[0178] At step 930, the DU may transmit a configuration related to port combining to the RU. Furthermore, the RU may transmit a configuration related to port combining to the DU. The configuration may include port combining parameters set based on capability information. The port combining parameters may be used to indicate port combining.

[0179] An RU that receives a parameter can apply the parameter immediately upon receipt. Alternatively, it can apply the parameter at a time designated by the DU. In this case, the DU can transmit information about the application time and whether to apply it to the RU through port combining enable. Alternatively, the RU can independently determine the application time and whether to apply it.

[0180] At step 940, the DU may transmit a port combining enabling or port combining enable signal to the RU. The port combining enabling or port combining enable signal may enable or disable the port combining configuration in the RU depending on whether port combining is applicable. In addition, the port combining enabling or port combining enable signal may include whether a parameter included in the configuration has been applied.

[0181] For example, the DU can turn on the enable signal in case of single-user scheduling and turn it off in case of multi-user scheduling, considering the SVD capability of the RU. In this case, in case of single-user scheduling, the enable signal can be transmitted so that SVD port combining is performed only on specific resources depending on the SVD performance capability of the RU.

[0182] This step is optional, and the port combining enabling or port combining enable signal can be included and transmitted and received in the process of transmitting and receiving the port combining configuration without this step.

[0183] In step 950, the DU may receive a port combining indication signal from the RU. The port combining indication signal may include whether to perform port combining according to the configuration set in the DU in the RU. Alternatively, the DU may receive an indication signal from the RU meaning ACK (Acknowledgement) or NACK (Negative Acknowledgement) for a resource specified by the DU. Alternatively, the DU may receive an indication signal from the RU regarding whether to apply SVD port combining in response to the port combining enabling or port combining enable signal of the DU. Alternatively, the RU may receive an indication signal from the RU regarding whether to apply SVD port combining according to the RU's own judgment.

[0184] The above indication may be composed of bits indicating whether a port combining configuration has been applied. The indication may be transmitted by being additionally included in a predefined message transmitted from the RU to the DU, or a separate message may be defined for the indication. Alternatively, the indication may indicate whether SVD has been applied using the Port Combining configuration proposed below. Alternatively, although the present disclosure describes a method of transmitting an indication from the RU to the DU as an example, a method of transmitting an indication from the DU to the RU may also be used when a signal to which SVD has been applied is transmitted from the DU to the RU. In addition, the step of transmitting the indication may be performed selectively. In step 960, the DU may receive a signal from the RU. The signal may be a signal to which SVD port combining has been applied. The signal may correspond to a message including I / Q data.

[0185] If the RU uses the SVD-based port combining method in step 970, the DU can receive a singular value from the RU. If the DU receives a singular value, the amount of computation required to calculate the singular value in the DU can be reduced, thereby reducing computational complexity.

[0186] If a singular value is not received, the DU can perform the matrix inversion process of FIG. 6 described above. Specifically, the DU can determine the square of the singular value for the channel H obtained by the Channel Estimator through the H*hermitian(H) operation. Specifically, the singular value can correspond to the square of Σ corresponding to the diagonal singular value matrix.

[0187] In contrast, a DU that receives a singular value from an RU can use the singular value, and thus can avoid performing the operation of finding the square value of the diagonal singular value matrix Σ through the H*hermitian(H) operation. In other words, when a DU receives a singular value, the amount of computation can be reduced.

[0188] This step is optional, and the DU can send a singular value request value to the RU during the process of transmitting and receiving port combining configuration without this step.

[0189] FIG. 10 is a diagram illustrating devices of an RU and a DU in a wireless communication system according to an embodiment of the present disclosure. FIG. 10 is a block diagram illustrating devices of an RU and a DU that can perform the present invention. According to FIG. 10, an RU (1000) includes a transceiver (1010), a control unit (820), a connection unit (1030), and a storage unit (1040). However, the components of the RU (1000) are not limited to the above-described example, and for example, the RU (1000) may include more or fewer components than the components illustrated. In addition, the transceiver (1010), the storage unit (1030), and the control unit (1020) may be implemented in the form of a single chip.

[0190] The transceiver (1010) can transmit and receive signals with the terminal. Here, the signals can include control information and data. To this end, the transceiver (1010) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts a received signal. However, this is only one embodiment of the transceiver (1010), and the components of the transceiver (1010) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (1010) can receive a signal through a wireless channel, output it to the control unit (1020), and transmit the signal output from the control unit (1020) through the wireless channel. In addition, the transceiver (1010) can be equipped with an RF transceiver for an LTE system and an RF transceiver for an NR system separately, or can perform physical layer processing of LTE and NR with a single transceiver.

[0191] The storage unit (1040) can store programs and data required for the operation of the RU. In addition, the storage unit (1040) can store control information or data included in signals transmitted and received by the RU. The storage unit (1040) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of storage units (1040).

[0192] The control unit (1020) can control a series of processes so that the RU (800) can operate according to the embodiment of the present disclosure described above. For example, the control unit (820) can receive a port combining configuration from a DU (Digital Unit), determine whether to perform SVD (Singular Value Decomposition) port combining based on the port combining configuration, transmit an indication indicating the SVD port combining to the DU when the SVD port combining is performed, and transmit a signal to which the SVD port combining is applied to the DU.

[0193] The connection unit (1030) is a device that connects the RU (1000) and the DU (1050), and can perform physical layer processing for message transmission and reception, and operations of transmitting messages to the DU (1050) and receiving messages from the DU (1050).

[0194] DU (1050) includes a control unit (1070), a connection unit (1060), and a storage unit (1080). However, the components of DU (1050) are not limited to the examples described above, and for example, DU (1050) may include more or fewer components than the illustrated components. In addition, the connection unit (1060), the storage unit (1080), and the control unit (1070) may be implemented in the form of a single chip.

[0195] The control unit (1060) can control a series of processes so that the DU (1050) can operate according to the embodiment of the present disclosure described above. For example, the control unit (1060) can transmit a port combining configuration to a RU (Remote Unit), and when SVD (Singular Value Decomposition) port combining is performed based on the port combining configuration, receive an indication indicating the SVD port combining from the RU, and receive a signal to which the SVD port combining is applied from the DU.

[0196] The storage unit (1040) can store programs and data required for the operation of the RU. In addition, the storage unit (1040) can store control information or data included in signals transmitted and received by the RU. The storage unit (1040) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD. In addition, there can be a plurality of storage units (1040).

[0197] The connection unit (1060) is a device that connects the RU (1000) and the DU (1050), and can perform physical layer processing for message transmission and reception, and operations of transmitting messages to the RU (1000) and receiving messages from the RU (1000).

[0198] In the specific embodiments of the present disclosure described above, components included in the invention are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0199] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are only specific examples to easily explain the technical contents of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the above-mentioned respective embodiments can be combined and operated with each other as needed. For example, parts of one embodiment of the present disclosure and parts of another embodiment can be combined with each other to operate a base station and a terminal. For example, parts of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment of the present disclosure can be combined with each other to operate a base station.

Claims

1. A method performed by a RU (Remote Unit) of a base station in a wireless communication system, A step of receiving a port combining configuration from a DU (Digital Unit) of the above base station; A step for checking whether SVD (Singular Value Decomposition) port combining is performed based on the above port combining configuration; When performing the above SVD port combining, a step of transmitting an indication indicating the SVD port combining to the DU; and A step of transmitting a signal to which the above SVD port combining is applied to the DU; A method characterized in that the above indication is used to decode a signal to which the SVD port combining is applied.

2. In paragraph 1, A step of receiving a capability request message related to port combining from the above DU; and In response to the capability request message, the method further comprises the step of transmitting a capability report message including capability information to the DU; A method characterized in that the above capability information includes information on at least one of a supportable port combining method or whether port combining can be performed.

3. In paragraph 1, A method further comprising: a step of transmitting information including at least one of the calculated values ​​according to the application of the SVD port combining to the DU.

4. In paragraph 1, A method characterized in that the above port combining configuration includes a port combining parameter including at least one of a used port combining method and a reduced number of ports.

5. A method performed by a DU (Digital Unit) of a base station in a wireless communication system, Step of transmitting port combining configuration to RU (Remote Unit); A step of receiving an indication of SVD (Singular Value Decomposition) port combining from the RU when SVD port combining is performed based on the port combining configuration; A step of receiving a signal to which the SVD port combining is applied from the RU; and A method characterized by comprising a step of decoding the signal based on the indication.

6. In paragraph 5, A step of transmitting a capability request message related to port combining to the above RU; and In response to the capability request message, the method further comprises the step of receiving, from the RU, a capability report message including capability information; A method characterized in that the above capability information includes information on at least one of a supportable port combining method or whether the RU can perform port combining.

7. In paragraph 5, A method further comprising: a step of receiving, from the RU, information including at least one of the calculated values ​​according to the application of the SVD port combining.

8. In paragraph 5, A method characterized in that the above port combining configuration includes a port combining parameter including at least one of a used port combining method and a reduced number of ports.

9. In the RU (Remote Unit) of the base station in a wireless communication system, Transmitter and receiver; and A control unit connected to the above transmitter and receiver; The above control unit: Receive port combining configuration from DU (Digital Unit), Based on the above port combining configuration, check whether SVD (Singular Value Decomposition) port combining is performed. When performing the above SVD port combining, an indication indicating the SVD port combining is transmitted to the DU, and The signal to which the above SVD port combining is applied is transmitted to the above DU, The above indication is a RU characterized in that it is used to decode the above signal.

10. In paragraph 9, the control unit: Receive a capability request message related to port combining from the above DU, and In response to the capability request message, a capability report message including capability information is transmitted to the DU. An RU, characterized in that the above capability information includes information on at least one of a supportable port combining method or whether the RU can perform port combining.

11. In paragraph 9, the control unit: A RU characterized by transmitting information including at least one of the calculated values ​​according to the application of the SVD port combining to the DU.

12. In paragraph 9, A RU characterized in that the above port combining configuration includes a port combining parameter including at least one of a used port combining method and a reduced number of ports.

13. In the DU (Digital Unit) of the base station in a wireless communication system, Transmitter and receiver; and Including a control unit connected to the above transmitter and receiver, The above control unit: Send the port combining configuration to the RU (Remote Unit), When the SVD (Singular Value Decomposition) port combining is performed based on the above port combining configuration, an indication indicating the SVD port combining is received from the RU, Receive a signal to which the SVD port combining is applied from the above DU, and A DU characterized by decoding the signal based on the above indication.

14. In paragraph 13, the control unit: Transmitting a capability request message related to port combining to the above RU, and In response to the capability request message, a capability report message including capability information is received from the RU, A DU characterized in that the above capability information includes information on at least one of a supportable port combining method or whether the RU can perform port combining.

15. In paragraph 13, the control unit: A DU characterized by receiving, from the RU, information including at least one of the calculated values ​​according to the application of the SVD port combining.

16. In paragraph 13, A DU characterized in that the above port combining configuration includes a port combining parameter including at least one of a used port combining method and a reduced number of ports.

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