Apparatus and method for processing uplink reference signal in fronthaul interface

Abstract

A method performed by a radio unit (RU) may comprise an operation of receiving, from a distributed unit (DU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information related to at least one physical resource block (PRB) for channel estimation using the SRSs. The method may comprise an operation of receiving the SRSs from a terminal on a plurality of PRBs. The method may comprise an operation of performing the channel estimation by using the SRSs. The method may comprise an operation of identifying, on the basis of the channel estimation using the SRSs, at least one channel coefficient for the at least one PRB indicated by the section extension information from among the plurality of PRBs. The method may comprise an operation of transmitting, to the DU, a message including information about the at least one channel coefficient for the at least one PRB.

Description

Device and method for processing uplink reference signals in a fronthaul interface

[0001] The following descriptions relate to devices and methods for processing an uplink reference signal (e.g., a sounding reference signal (SRS)) in a fronthaul interface.

[0002] In a time division duplex (TDD) system, when channel reciprocity exists, the base station can estimate the downlink channel based on measurements of an uplink reference signal (e.g., a sounding reference signal (SRS)). For example, the base station can obtain channel information between the terminal and the base station based on measurements of the uplink reference signal. For example, the base station can determine beamforming weights for downlink transmission based on the channel information.

[0003] The above information may be provided as background art to aid in understanding the present disclosure. No claim or determination is made as to whether any of the above is applicable as prior art related to the present disclosure.

[0004] A method performed by a radio unit (RU) is provided. The method may include receiving, from a distributed unit (DU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information associated with at least one physical resource block (PRB) for channel estimation using the SRSs. The method may include receiving the SRSs from a terminal on a plurality of PRBs. The method may include performing the channel estimation using the SRSs. The method may include identifying, based on the channel estimation using the SRSs, at least one channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs. The method may include transmitting, to the DU, a message including information about the at least one channel coefficient for the at least one PRB.

[0005] An RU is provided. The RU may include communication circuitry. The RU may include a memory storing instructions and including one or more storage media. For example, the RU may include at least one processor including processing circuitry. For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive from a DU a control plane message including section information for identifying SRSs and section extension information associated with at least one PRB for channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive from a terminal the SRSs on a plurality of PRBs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to perform the channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to identify at least one channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs based on the channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to transmit a message to the DU including information about the at least one channel coefficient for the at least one PRB.

[0006] A non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed by an RU including at least one processor, cause the RU to receive from a DU a control plane message including section information for identifying SRSs and section extension information associated with at least one PRB for channel estimation using the SRSs. The one or more programs may include instructions that, when executed by the RU including at least one processor, cause the RU to receive from a terminal the SRSs on a plurality of PRBs. The one or more programs may include instructions that, when executed by the RU including at least one processor, cause the RU to perform the channel estimation using the SRSs. The one or more programs may include instructions that, when executed by an RU including at least one processor, cause the RU to identify a channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs based on a channel estimation of the SRSs. The one or more programs may include instructions that, when executed by an RU including at least one processor, cause the RU to transmit a message to the DU, the message including information about the at least one channel coefficient for the at least one PRB.

[0007] A method performed by a DU is provided. The method may include transmitting, to an RU, a control plane message including section information for identifying SRSs and section extension information associated with at least one PRB for channel estimation using the SRSs. The method may include receiving, from the RU, a message including information regarding at least one channel coefficient for the at least one PRB indicated by the section extension information. The at least one channel coefficient may be associated with the channel estimation using the SRSs performed in the RU.

[0008] A DU is provided. The DU may include communication circuitry. The DU may include a memory storing instructions and including one or more storage media. The DU may include at least one processor including processing circuitry. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to transmit a control plane message to an RU, the control plane message including section information for identifying SRSs and section extension information associated with at least one PRB for channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to receive from the RU a message including information regarding at least one channel coefficient for the at least one PRB indicated by the section extension information. The at least one channel coefficient may be associated with the channel estimation using the SRSs performed in the RU.

[0009] A non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium may store one or more programs. The one or more programs may include instructions that, when executed by a DU including at least one processor, cause the DU to transmit to an RU a control plane message including section information for identifying SRSs and section extension information associated with at least one PRB for channel estimation using the SRSs. The one or more programs may include instructions that, when executed by the DU including at least one processor, cause the DU to receive from the RU a message including information regarding at least one channel coefficient for the at least one PRB indicated by the section extension information. The at least one channel coefficient may be associated with the channel estimation performed in the RU.

[0010] In connection with the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0011] Figure 1 illustrates an example of a wireless communication system.

[0012] Figure 2 illustrates the interface between a DU (distributed unit) and a RU (radio unit).

[0013] Figure 3a is a simplified block diagram of DU.

[0014] Figure 3b is a simplified block diagram of the RU.

[0015] Figure 4 illustrates an example of function split between DU and RU.

[0016] Figure 5 shows an example of SRS channel estimation by DU.

[0017] Figure 6 illustrates an example of management plane signaling for SRS channel estimation.

[0018] Figure 7 illustrates an example of control plane signaling for SRS channel estimation.

[0019] Figure 8 illustrates an example of signaling between a DU and a RU for SRS channel estimation.

[0020] Figure 9 illustrates an example of section type information of a control plane message for SRS channel estimation.

[0021] Figure 10 illustrates an example of section extension information of a control plane message for SRS channel estimation.

[0022] Figure 11 illustrates an example of section extension information of a control plane message for SRS channel estimation.

[0023] Figure 12a illustrates an example of section type information of a control plane message for SRS channel estimation.

[0024] Figure 12b illustrates an example of section extension information of a control plane message for SRS channel estimation.

[0025] Figure 13 is a flowchart illustrating the operation of DU for SRS channel estimation.

[0026] Figure 14 shows an example of SRS channel estimation according to RU capability.

[0027] The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

[0028] The various embodiments of the present disclosure described below illustrate a hardware-based approach as an example. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0029] In the following description, terms referring to signals (e.g., packet, message, signal, information, signaling), terms referring to resources (e.g., section, symbol, slot, subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), occasion), terms for operational states (e.g., step, operation, procedure), terms referring to data (e.g., packet, message, user stream, information, bit, symbol, codeword), terms referring to channels, terms referring to network entities (distributed unit (DU), radio unit (RU), central unit (CU), CU-CP (control plane), CU-UP (user plane), O-DU (O-RAN (open radio access network) DU), O-RU (O-RAN RU), O-CU (O-RAN Terms such as CU), O-CU-UP (O-RAN CU-CP), O-CU-CP (O-RAN CU-CP)), and components of the device are provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. In addition, terms such as '...part', '...machine', '...object', and '...body' used below may mean at least one shape structure or a unit that processes a function.

[0030] In addition, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled, but this is merely a description for expressing an example and does not exclude descriptions such as "more than" or "less than." A condition described as "more than" may be replaced with "more than," a condition described as "less than" may be replaced with "less than," and a condition described as "more than and less than" may be replaced with "more than and less than." In addition, hereinafter, "A" to "B" mean at least one of elements from A (including A) to B (including B). hereinafter, "C" and / or "D" mean at least one of "C" or "D," that is, including {"C", "D", "C" and "D"}.

[0031] Although this disclosure describes embodiments using terminology used in certain communication standards (e.g., 3rd Generation Partnership Project (3GPP)), this is merely an example for illustrative purposes. Embodiments of this disclosure can also be applied to other communication and broadcasting systems.

[0032] Figure 1 illustrates an example of a wireless communication system.

[0033] Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as some of the nodes utilizing a wireless channel in a wireless communication system. Although FIG. 1 illustrates only one base station, the wireless communication system may further include other base stations identical or similar to the base station (110).

[0034] The base station (110) is a network infrastructure that provides wireless access to the terminal (120). The base station (110) has coverage defined based on the distance at which a signal can be transmitted. In addition to the base station, the base station (110) may be referred to as an 'access point (AP)', 'eNodeB (eNB)', '5th generation node', 'next generation nodeB (gNB)', 'wireless point', 'transmission / reception point (TRP)', or other terms having equivalent technical meanings.

[0035] The terminal (120) is a device used by a user and communicates with the base station (110) via a wireless channel. The link from the base station (110) to the terminal (120) is referred to as a downlink (DL), and the link from the terminal (120) to the base station (110) is referred to as an uplink (UL). In addition, although not shown in FIG. 1, the terminal (120) and another terminal may communicate with each other via a wireless channel. In this case, the link between the terminal (120) and another terminal (device-to-device link, D2D) is referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal (120) may be operated without the involvement of a user. For example, the terminal (120) may be a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, for example, the terminal (120) may be an NB (narrowband)-IoT (internet of things) device.

[0036] The terminal (120) may be referred to as a terminal, or other terms such as 'user equipment (UE),' 'customer premises equipment (CPE),' 'mobile station,' 'subscriber station,' 'remote terminal,' 'wireless terminal,' 'electronic device,' or 'user device,' or other terms having equivalent technical meanings.

[0037] The base station (110) and the terminal (120) can perform beamforming. The base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). In addition, the base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively high frequency band (e.g., FR 2 (or, FR 2-1, FR 2-2, FR 2-3), FR 3 of NR), millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz)). To improve channel gain, the base station (110) and the terminal (120) can perform beamforming. Here, the beamforming can include transmission beamforming and reception beamforming. The base station (110) and the terminal (120) can impart directionality to the transmitted or received signal. To this end, the base station (110) and the terminal (120) can select serving beams through a beam search or beam management procedure. After the serving beams are selected, subsequent communication can be performed through resources that have a QCL relationship with the resource that transmitted the serving beams.

[0038] If large-scale characteristics of a channel carrying a symbol on a first antenna port can be inferred from a channel carrying a symbol on a second antenna port, the first antenna port and the second antenna port can be evaluated to have a QCL relationship. For example, the large-scale characteristics may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and a spatial receiver parameter.

[0039] Although both the base station (110) and the terminal (120) are described as performing beamforming in FIG. 1, the embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Furthermore, the base station may or may not perform beamforming. That is, either only one of the base station and the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0040] In the present disclosure, a beam refers to a spatial flow of a signal in a wireless channel, and is formed by one or more antennas (or antenna elements), and this forming process may be referred to as beamforming. Beamforming may include at least one of analog beamforming and digital beamforming (e.g., precoding). Reference signals transmitted based on beamforming may include, for example, a demodulation-reference signal (DM-RS), a channel state information-reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), and a sounding reference signal (SRS). In addition, as a configuration for each reference signal, an IE such as a CSI-RS resource or an SRS-resource may be used, and this configuration may include information associated with the beam. Information associated with a beam may mean whether the configuration (e.g., a CSI-RS resource) uses the same spatial domain filter as another configuration (e.g., another CSI-RS resource within the same CSI-RS resource set) or a different spatial domain filter, or whether it is quasi-co-located (QCL) with a reference signal, and if so, what type it is (e.g., QCL type A, B, C, D).

[0041] In the past, in communication systems with relatively large cell radius of base stations, each base station was installed to include the functions of a digital processing unit (or distributed unit (DU)) and a radio frequency (RF) processing unit (or radio unit (RU)). However, as higher frequency bands are used in 4G (4th generation) and / or subsequent communication systems (e.g., 5G) and the cell coverage of base stations becomes smaller, the number of base stations to cover a specific area has increased. The installation costs for operators to install base stations have also increased. In order to minimize the installation costs of base stations, a structure has been proposed in which the DU and RU of the base station are separated, one or more RUs are connected to one DU via a wired network, and one or more RUs are geographically distributed to cover a specific area. Hereinafter, the deployment structure and expansion examples of base stations according to various embodiments of the present disclosure are described through FIG. 2.

[0042] Figure 2 illustrates the interface between DU and RU.

[0043] FIG. 2 illustrates an interface between a distributed unit (DU) and a radio unit (RU). The interface between the DU and the RU may include a fronthaul interface. Fronthaul refers to entities between a wireless LAN and a base station, unlike backhaul between a base station and a core network. FIG. 2 illustrates an example of a fronthaul structure between a DU (210) and one RU (220), but this is merely for convenience of explanation and the present disclosure is not limited thereto. In other words, embodiments of the present disclosure may also be applied to a fronthaul structure between one DU and multiple RUs. For example, embodiments of the present disclosure may be applied to a fronthaul structure between one DU and two RUs. Furthermore, embodiments of the present disclosure may also be applied to a fronthaul structure between one DU and three RUs.

[0044] In one example, DU (210) may be referred to as a DU (digital unit). In one example, RU (220) may be referred to as an MMU (massive multiple input multiple output unit).

[0045] Referring to FIG. 2, a base station (110) may include a DU (210) and an RU (220). A fronthaul (215) between the DU (210) and the RU (220) may be operated via an Fx interface. For operation of the fronthaul (215), an interface such as an enhanced common public radio interface (eCPRI) or radio over ethernet (ROE) may be used, for example.

[0046] As communication technology advances, mobile data traffic increases, significantly increasing the bandwidth requirements for the fronthaul between the digital unit and the wireless unit. In a deployment such as a centralized / cloud radio access network (C-RAN), the DU (210) performs functions for the packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical (PHY) layer, and the RU (220) can be implemented to perform functions for the PHY layer in addition to the RF (radio frequency) function.

[0047] The DU (210) may be responsible for upper layer functions of a wireless network. For example, the DU (210) may perform functions of the MAC layer and a part of the PHY layer. Here, a part of the PHY layer refers to functions performed at a higher level among the functions of the PHY layer, and may include, for example, channel encoding (or channel decoding), scrambling (or descrambling), modulation (or demodulation), and layer mapping (or layer demapping). According to an embodiment, if the DU (210) complies with the O-RAN standard, it may be referred to as an O-DU (O-RAN DU) (or DU). The DU (210) may be replaced with a first network entity for a base station (e.g., gNB) in embodiments of the present disclosure, if necessary.

[0048] The RU (220) may be responsible for lower layer functions of a wireless network. For example, the RU (220) may perform a part of the PHY layer, an RF function. Here, a part of the PHY layer refers to functions of the PHY layer that are performed at a relatively lower level than the DU (210), and may include, for example, iFFT transformation (or FFT transformation), CP (cyclic prefix) insertion (CP removal), and digital beamforming. An example of such specific functional separation is described in detail in FIG. 4. The RU (220) may be referred to as an 'access unit (AU)', an 'access point (AP)', a 'transmission / reception point (TRP)', a 'remote radio head (RRH)', a 'radio unit (RU)', or other terms having an equivalent technical meaning thereto. In one embodiment, if RU (220) complies with the O-RAN standard, it may be referred to as O-RU (O-RAN RU) (or RU). RU (220) may be replaced with a second network entity for a base station (e.g., gNB) in embodiments of the present disclosure, if necessary.

[0049] For example, a base station may be implemented in a distributed deployment according to a centralized unit (CU) configured to perform functions of upper layers of an access network (e.g., packet data convergence protocol (PDCP) and radio resource control (RRC)) and a distributed unit (DU) configured to perform functions of lower layers. At this time, the distributed unit (DU) may include a digital unit (DU) and a radio unit (RU). Between a core (e.g., 5GC (5G core) or NGC (next generation core)) network and a radio network (RAN), the base station may be implemented in a structure in which the CU, DU, and RU are deployed in that order. The interface between the CU and the distributed unit (DU) may be referred to as an F1 interface.

[0050] For example, a centralized unit (CU) may be connected to one or more DUs and may be responsible for functions at a higher layer than the DU. For example, the CU may be responsible for functions at the RRC (radio resource control) and PDCP (packet data convergence protocol) layers, while the DU and RU may be responsible for functions at lower layers. The DU may perform some functions (high PHY) of the RLC (radio link control), MAC (media access control), and PHY (physical) layers, and the RU may be responsible for the remaining functions (low PHY) of the PHY layer. In addition, for example, a digital unit (DU) may be included in a distributed unit (DU) depending on the implementation of a distributed deployment of a base station. Hereinafter, unless otherwise defined, the operations of DU and RU are described, but various embodiments of the present disclosure can be applied to both a base station deployment including a CU and a deployment in which the DU is directly connected to the core network (i.e., a base station in which the CU and DU are integrated into a single entity (e.g., an NG-RAN node)).

[0051] Figure 3a is a simplified block diagram of DU.

[0052] The configuration illustrated in Fig. 3a can be understood as a configuration of the DU (distributed unit) (210) of Fig. 2a as part of a base station. Terms such as "...unit" and "...unit" used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0053] Referring to FIG. 3a, DU (210) may include a transceiver (310), a memory (320), and a processor (330).

[0054] The transceiver (310) can perform functions for transmitting and receiving signals in a wired communication environment. The transceiver (310) can include a wired interface for controlling a direct connection between the device and another device via a transmission medium (e.g., copper wire, optical fiber, etc.). For example, the transceiver (310) can transmit an electrical signal to another device via copper wire or perform conversion between an electrical signal and an optical signal. The DU (210) can communicate with the RU (220) via the transceiver (310). The DU (210) can be connected to a core network or a centralized unit (CU) of a distributed arrangement via the transceiver (310).

[0055] The transceiver (310) may perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver (310) may perform a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the transceiver (310) may generate complex symbols by encoding and modulating the transmitted bit stream. For example, when receiving data, the transceiver (310) may decode the baseband signal to restore the received bit stream. For example, the transceiver (310) may include multiple transmission and reception paths. For example, the transceiver (310) may be connected to the core network or to other nodes (e.g., an integrated access backhaul (IAB)).

[0056] The transceiver (310) can transmit and receive signals. For example, the transceiver (310) can transmit a management plane (M-plane) message. For example, the transceiver (310) can receive a synchronization plane (S-plane) message. For example, the transceiver (310) can transmit a control plane (C-plane) message. For example, the transceiver (310) can transmit a user plane (U-plane) message. For example, the transceiver (310) can receive a user plane message. Although FIG. 3A only illustrates the transceiver (310), in other implementations, the DU (210) may include two or more transceivers.

[0057] The transceiver (310) can transmit and receive signals as described above. Accordingly, all or part of the transceiver (310) may be referred to as a "communication unit," a "transmitter," a "receiver," or a "transmitter-receiver unit." Furthermore, in the following description, transmission and reception performed via a wireless channel may be used to mean processing performed by the transceiver (310) as described above.

[0058] Although not illustrated in FIG. 3A, the transceiver (310) may further include a backhaul transceiver for connection to the core network or other base stations. For example, the backhaul transceiver may provide an interface for communicating with other nodes within the network. For example, the backhaul transceiver may convert a bit stream transmitted from the base station to other nodes, such as other access nodes, other base stations, upper nodes, the core network, etc., into a physical signal, and may convert a physical signal received from other nodes into a bit stream.

[0059] The memory (320) can store data such as basic programs, application programs, and setting information for the operation of the DU (210). For example, the memory (320) may be referred to as a storage unit. For example, the memory (320) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. For example, the memory (320) may provide stored data upon request from the processor (330).

[0060] The processor (330) can control the overall operations of the DU (210). For example, the processor (330) may be referred to as a control unit. For example, the processor (330) can transmit and receive signals through the transceiver (310) (or through a backhaul communication unit). For example, the processor (330) can write and read data to and from the memory (320). For example, the processor (330) can control the operations of the DU (210) by executing instructions stored in the memory (320). For example, the processor (330) can correspond to multiple processors that collectively perform multiple operations by dividing them among the processors. For example, the processor (330) can perform the functions of a protocol stack required by a communication standard. Although FIG. 3a illustrates only the processor (330), in other implementation examples, the DU (210) may include two or more processors.

[0061] In one embodiment, the processor (330) may include various processing circuits and / or multiple processors. For example, the term "processor" as used herein, including in the claims, may include various processing circuits including at least one processor, one or more of which may be configured to individually and / or collectively perform the various functions described below in a distributed manner. As used herein, when "processor," "at least one processor," and "one or more processors" are described as being configured to perform various functions, these terms encompass, for example, and without limitation, situations where one processor performs some of the recited functions and other processor(s) perform other parts of the recited functions, as well as situations where one processor may perform all of the recited functions. Additionally, the at least one processor may include a combination of processors that perform the various functions enumerated / disclosed, for example, in a distributed manner. At least one processor is capable of executing program instructions to accomplish or perform various functions.

[0062] The configuration of DU (210) illustrated in FIG. 3A is merely an example, and examples of DUs performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 3A. In some embodiments, some configurations may be added, deleted, or changed.

[0063] Figure 3b is a simplified block diagram of the RU.

[0064] The configuration illustrated in Fig. 3b can be understood as a configuration of the RU (radio unit) (220) of Fig. 2b as part of a base station. Terms such as "...unit" and "...unit" used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0065] Referring to FIG. 3b, the RU (220) may include an RF (radio frequency) transceiver (360), a front-haul transceiver (365), a memory (370), and a processor (380).

[0066] The RF transceiver (360) can perform functions for transmitting and receiving signals via a wireless channel. For example, the RF transceiver (360) can up-convert a baseband signal into an RF band signal and then transmit the up-converted signal via an antenna, and down-convert an RF band signal received via the antenna into a baseband signal. For example, the RF transceiver (360) can include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and the like.

[0067] The RF transceiver (360) may include multiple transmit / receive paths. For example, the RF transceiver (360) may include an antenna section. For example, the RF transceiver (360) may include at least one antenna array composed of multiple antenna elements. For example, in terms of hardware, the RF transceiver (360) may be composed of digital circuits and analog circuits (e.g., a radio frequency integrated circuit (RFIC)). For example, the digital circuits and analog circuits may be implemented in a single package. For example, the RF transceiver (360) may include multiple RF chains. For example, the RF transceiver (360) may perform beamforming. For example, the RF transceiver (360) may apply beamforming weights to a signal to be transmitted / received in order to impart directionality according to the settings of the processor (380). For example, the RF transceiver (360) may include an RF block (or RF section).

[0068] For example, the RF transceiver (360) can transmit and receive signals on a radio access network. For example, the RF transceiver (360) can transmit a downlink signal. For example, the downlink signal can include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS), a demodulation (DM)-RS), system information (e.g., a MIB, a SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data. For example, the RF transceiver (360) can receive an uplink signal. For example, the uplink signal may include a random access related signal (e.g., a random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), a reference signal (e.g., a sounding reference signal (SRS), DM-RS), or a power headroom report (PHR). Although FIG. 3b only illustrates the RF transceiver (360), in other implementations, the RU (220) may include two or more RF transceivers.

[0069] The fronthaul transceiver (365) can transmit and receive signals. For example, the fronthaul transceiver (365) can transmit and receive signals on the fronthaul interface. For example, the fronthaul transceiver (365) can receive management plane (M-plane) messages. For example, the fronthaul transceiver (365) can receive synchronization plane (S-plane) messages. For example, the fronthaul transceiver (365) can receive control plane (C-plane) messages. For example, the fronthaul transceiver (365) can transmit user plane (U-plane) messages. For example, the fronthaul transceiver (365) can receive user plane messages. Although FIG. 3b illustrates only the fronthaul transceiver (365), in other implementation examples, the RU (220) may include two or more fronthaul transceivers.

[0070] The RF transceiver (360) and the fronthaul transceiver (365) can transmit and receive signals as described above. Accordingly, all or part of the RF transceiver (360) and the fronthaul transceiver (365) may be referred to as a "communication unit," a "transmitter," a "receiver," or a "transmitter-receiver unit." In the following description, transmission and reception performed through a wireless channel may be used to mean that the processing described above is performed by the RF transceiver (360).

[0071] The memory (370) can store data such as basic programs, application programs, and setting information for the operation of the RU (220). For example, the memory (370) may be referred to as a storage unit. For example, the memory (370) may be configured as volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. For example, the memory (370) provides stored data according to a request from the processor (380). For example, the memory (370) may include memory for conditions, commands, or setting values ​​related to the SRS transmission method.

[0072] The processor (380) can control the overall operations of the RU (220). For example, the processor (380) may be referred to as a control unit. For example, the processor (380) can transmit and receive signals through the RF transceiver (360) or the fronthaul transceiver (365). For example, the processor (380) can write and read data to and from the memory (370). For example, the processor (380) can control the operations of the RU (220) by executing instructions stored in the memory (370). For example, the processor (380) can correspond to multiple processors that collectively perform multiple operations by dividing them among the processors. For example, the processor (380) can perform the functions of a protocol stack required by a communication standard. Although FIG. 3B only illustrates the processor (380), according to another implementation example, the RU (220) may include two or more processors. For example, the processor (380) may be a set of instructions or codes stored in the memory (370), or may be a storage space that stores instructions / codes or instructions / codes that are temporarily residing in the processor (380), or may be a part of the circuitry that constitutes the processor (380). For example, the processor (380) may include various modules for performing communication. For example, the processor (380) may control the RU (220) to perform operations according to the embodiments described below.

[0073] In one embodiment, the processor (380) may include various processing circuits and / or multiple processors. For example, the term "processor," as used herein, including in the claims, may include various processing circuits including at least one processor, one or more of which may be configured to individually and / or collectively perform the various functions described below in a distributed manner. As used herein, when "processor," "at least one processor," and "one or more processors" are described as being configured to perform various functions, these terms encompass, for example, and without limitation, situations where one processor performs some of the recited functions and other processor(s) perform other parts of the recited functions, as well as situations where one processor may perform all of the recited functions. Additionally, the at least one processor may include a combination of processors that perform the various functions enumerated / disclosed, for example, in a distributed manner. At least one processor is capable of executing program instructions to accomplish or perform various functions.

[0074] The configuration of RU (220) illustrated in FIG. 3b is merely an example, and examples of RUs performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 3b. In some embodiments, some configurations may be added, deleted, or changed.

[0075] Figure 4 illustrates an example of function splitting between DUs and RUs. As wireless communication technologies advance (e.g., the introduction of 5G (5th generation) communication systems (or NR communication systems), the frequency bands used have increased. As the cell radius of base stations decreases, the number of RUs (radio units) required for installation has further increased. In 5G communication systems, the amount of data to be transmitted has increased by about 10 times or more, so the transmission capacity of the wired network transmitted through the fronthaul has increased. Due to the factors described above, the installation cost of the wired network in the 5G communication system may increase significantly. Therefore, in order to lower the transmission capacity of the wired network and reduce the installation cost of the wired network, function splitting may be utilized to reduce the fronthaul transmission capacity by transferring some of the modem functions of the DU (distributed unit) to the RU.

[0076] To reduce the burden on the DU, the role of the RU, which is currently solely responsible for RF (radio frequency) functions, can be expanded to include at least some physical layer functions. As the RU performs higher-layer functions, its throughput increases, which can increase the transmission bandwidth in the protohaul and reduce the latency requirements due to response processing. On the other hand, as the RU performs higher-layer functions, the virtualization gains decrease, and the size, weight, and cost of the RU may increase. Considering the trade-offs of the above-described advantages and disadvantages, it is necessary to implement an optimal functional separation.

[0077] Referring to FIG. 4, functional separations in the physical layer below the MAC (medium access control) layer are illustrated. In the case of the downlink (DL) that transmits signals to a terminal through a wireless network, the base station can sequentially perform channel encoding / scrambling, modulation, layer mapping, antenna port mapping, RE (resource element) mapping, digital beamforming (e.g., precoding), iFFT (inverse fast Fourier transform) conversion / CP (cyclic prefix) insertion, and RF conversion. For uplink (UL), which receives signals from terminals through a wireless network, the base station can sequentially perform RF conversion, FFT conversion / CP removal, digital beamforming (e.g., pre-combining, RE de-mapping, channel estimation, layer de-mapping, demodulation, and decoding / descrambling). The separation of uplink functions and downlink functions can be defined in various types depending on the needs of vendors, discussions in standards, etc., according to the trade-offs described above.

[0078] In one embodiment, according to the first functional separation (405), the RU (220) may perform an RF function. For example, according to the first functional separation (405), the DU (210) may perform a PHY function. For example, according to the first functional separation (405), the PHY function within the RU (220) may not be substantially implemented. In one example, the first functional separation (405) may be referred to as option 8.

[0079] In one embodiment, according to the second functional separation (410), the RU (220) may perform iFFT transform / CP insertion in the downlink. For example, according to the second functional separation (410), the DU (210) may perform FFT transform / CP removal in the uplink. For example, according to the second functional separation (410), the DU (210) may perform the remaining PHY functions. In one example, the second functional separation (410) may be referred to as Option 7-1.

[0080] In one embodiment, according to the third functional separation (420a), the RU (220) may perform iFFT transform / CP insertion in the downlink. For example, according to the third functional separation (420a), the RU (220) may perform FFT transform / CP removal and digital beamforming in the uplink. For example, according to the third functional separation (420a), the DU (210) may perform the remaining PHY functions. In one example, the third functional separation (420a) may be referred to as Option 7-2x Category A.

[0081] In one embodiment, according to the fourth functional separation (420b), the RU (220) may perform iFFT transform / CP insertion and digital beamforming in the downlink. For example, according to the fourth functional separation (420b), the RU (220) may perform FFT transform / CP removal and digital beamforming in the uplink. For example, according to the fourth functional separation (420b), the DU (210) may perform the remaining PHY functions. In one example, the fourth functional separation (420b) may be referred to as Option 7-2x Category B.

[0082] In one embodiment, according to the fifth functional separation (425), the RU (220) may perform iFFT transform / CP insertion, digital beamforming, and RE mapping in the downlink. For example, according to the fifth functional separation (425), the RU (220) may perform FFT transform / CP removal, digital beamforming, and RE de-mapping in the uplink. For example, according to the fifth functional separation (425), the DU (210) may perform the remaining PHY functions. In one example, the fifth functional separation (425) may be referred to as Option 7-2.

[0083] In one embodiment, according to the sixth functional separation (430), the RU (220) may perform iFFT transform / CP insertion, digital beamforming, RE mapping, antenna port mapping, layer mapping, and modulation in the downlink. For example, according to the sixth functional separation (430), the RU (220) may perform FFT transform / CP removal, digital beamforming, RE de-mapping, channel estimation, layer de-mapping, and demodulation in the uplink. For example, according to the sixth functional separation (430), the DU (210) may perform the remaining PHY functions. In one example, the sixth functional separation (430) may be referred to as Option 7-3.

[0084] In one embodiment, according to the seventh functional separation (440), the RU (220) may perform iFFT transform / CP insertion, digital beamforming, RE mapping, antenna port mapping, layer mapping, modulation, and channel encoding / scrambling in the downlink. For example, according to the seventh functional separation (440), the RU (220) may perform FFT transform / CP removal, digital beamforming, RE de-mapping, channel estimation, layer de-mapping, demodulation, and channel decoding / descrambling in the uplink. In one example, the seventh functional separation (440) may be referred to as Option 6.

[0085] Fig. 5 illustrates an example of SRS channel estimation by a DU. Fig. 5 illustrates a case where SRS (sounding reference signal) channel estimation (CE) is performed by a DU (210) according to the fourth functional separation of Fig. 4 (e.g., option 7-2x category B).

[0086] Referring to FIG. 5, in operation 501, DU (210) may transmit sounding reference signal (SRS) symbol information to RU (220). In one embodiment, DU (210) may transmit a first control plane (C-plane) message including SRS symbol information to RU (220). For example, SRS symbol information may include time information and frequency information for capturing (or receiving, acquiring) an SRS signal.

[0087] In operation (502), the DU (210) may receive SRS data from the RU (220). In one embodiment, the SRS data may include data of an SRS captured (or received, acquired) by the RU (220) based on SRS symbol information.

[0088] In operation 503, the DU (210) may perform SRS channel estimation (CE). In one embodiment, the DU (210) may perform SRS channel estimation based on SRS data received from the RU (220). For example, the DU (210) may generate (or identify, obtain) channel information based on the SRS channel estimation. For example, the channel information may include channel coefficients for a channel between a base station (e.g., the DU (210) and the RU (220)) and the terminal (120).

[0089] In operation 504, the DU (210) may transmit channel information to the RU (220). In one embodiment, the DU (210) may transmit a second control plane message including the channel information to the RU (220). For example, the RU (220) may identify (or determine) beamforming weights for downlink transmission based on the received channel information.

[0090] As described above, in the fourth functional separation (e.g., Option 7-2x Category B), the DU (210) can perform SRS channel estimation. In order to perform SRS channel estimation, the DU (210) must receive SRS data and transmit channel information through an interface (I / F) (e.g., enhanced common public radio interface (eCPRI)) between the DU (210) and the RU (220). However, since the fronthaul capacity is limited, the exchange of SRS signals and channel information through the interface between the DU (210) and the RU (220) may cause a processing delay for channel information based beamforming (CIBF). For example, the interval between the reception time of the SRS and the determination time of the beamforming weights may increase. Since the channel changes over time, the performance of the CIBF may be degraded by the channel aging effect caused by the processing delay.

[0091] To solve the above-described problem, in the embodiments of the present disclosure, SRS channel estimation can be performed by the RU (220). Since SRS channel estimation is performed by the RU (220), the burden on the interface between the DU (210) and the RU (220) can be reduced. Since the exchange of SRS signals and overall channel information through the interface between the DU (210) and the RU (220) is not performed, the processing delay for CIBF can be reduced. Since the processing delay for CIBF is reduced, the degradation of CIBF performance due to channel aging can be prevented. Hereinafter, the present disclosure describes signaling between the DU (210) and the RU (220) to enable SRS estimation by the RU (220).

[0092] Figure 6 illustrates an example of management plane signaling for SRS channel estimation. As described in Figure 4, sounding reference signal (SRS) channel estimation (CE) may be performed by either the DU (210) or the RU (220) depending on the functional separation. For example, according to the fourth functional separation (420b) (e.g., Option 7-2x Category B), SRS channel estimation may be performed by the DU (210). For example, according to the sixth functional separation (430) (e.g., Option 7-3), SRS channel estimation may be performed by the RU (220). Figure 6 illustrates a negotiation procedure for identifying whether the RU (220) supports the channel estimation function. For example, the negotiation procedure may be performed in the management plane (M-plane).

[0093] Referring to FIG. 6, in operation 601, RU (220) may transmit RU capability information to DU (210). In one embodiment, RU (220) may transmit a first management plane message including RU capability information to DU (210).

[0094] In one embodiment, the RU capability information may include parameters associated with the SRS CE. For example, the RU capability information may include a parameter indicating whether SRS channel estimation by the RU (220) is supported (e.g., 'srs-ce-supported'), a parameter indicating the maximum value of the SRS repetition factor supported by the RU (220) (e.g., 'max-supported-repetition-factor'), a parameter indicating the maximum number of terminals supported by the RU (220) (e.g., 'max-number-of-ues'), a parameter indicating the transmission comb supported by the RU (220) (e.g., 'transmission-comb'), a parameter indicating the number of cyclic shifts per SRS symbol supported by the RU (220) (e.g., 'supported-cs'), a parameter indicating the maximum number of symbols per slot supported by the RU (220) (e.g., 'max-num-of-symbol-per slot'), a parameter indicating the maximum number of symbols per frame supported by the RU (220) 'max-num-of-symbols-per-frame'), a parameter indicating the range of signal-to-interference plus noise ratio (SINR) reference levels supported by the RU (220) (e.g., 'min / max-supported-srs-sinr-reference-level'), or a combination thereof. In one example, the RU capability information may be defined according to [Table 1] below.

[0095] M-plane parametersTypeRangesrs-ce-supportedBooleanTRUE, FALSEmax-supported-repetition-factorunit 8max-number-of-uesunit 16srs-ce-capabilities[transmission-comb]listtransmission-combenumeration{n2, n4, n8}supported-csunit 81~12max-num-of-symbol-per-slotunit 81~max-num-of-symbol-per-frameunit 81~min / max-supported-srs-sinr-reference-level

[0096] In one embodiment, a parameter (e.g., 'srs-ce-supported') may indicate whether SRS channel estimation by the RU (220) is supported. For example, the parameter may be set to 'true' to indicate that SRS channel estimation by the RU (220) is supported. For example, the parameter may be set to 'false' to indicate that SRS channel estimation by the RU (220) is not supported.

[0097] In one embodiment, a parameter (e.g., 'max-supported-repetition-factor') may indicate a maximum value of an SRS repetition factor supported by the RU (220). In one example, the parameter may indicate a value of one of 1, 2, or 4. In another example, the parameter may indicate a value of one of 1, 2, 4, 5, 6, 7, 8, 10, 12, or 14.

[0098] In one embodiment, a parameter (e.g., 'max-number-of-ues') may indicate the maximum number of terminals supported by the RU (220). For example, when SRS channel estimation is performed by the RU (220), the RU (220) may store channel information in the memory (370) of the RU (220). For example, since the channel information is stored in the memory (370) of the RU (220), the value indicated by the parameter may be determined based on the capacity (or capability) of the memory (370) of the RU (220).

[0099] In one embodiment, a parameter (e.g., 'transmission-comb') may indicate a comb size supported by the RU (220). For example, the comb size may correspond to the spacing between subcarriers of an SRS transmitted by the terminal (120). In one example, if the comb size is 2, the terminal (120) may transmit an SRS every two subcarriers. In one example, the parameter may indicate 2, 4, 8, or a combination thereof. In one example, the parameter may enumerate 2, 4, 8, or a combination thereof.

[0100] In one embodiment, a parameter (e.g., 'supported-cs') may indicate the number of cyclic shifts per SRS symbol supported by the RU (220).

[0101] In one embodiment, a parameter (e.g., 'max-num-of-symbol-per-slot') may indicate the maximum number of symbols per slot supported by the RU (220). In one example, the parameter may indicate a value of one of 1, 2, 4, 5, 6, 7, 8, 10, 12, or 12.

[0102] In one embodiment, a parameter (e.g., 'max-num-of-symbol-per-frame') may indicate the maximum number of symbols per frame supported by the RU (220). For example, since SRS is not transmitted in all slots of a frame, the parameter may not be related to a parameter (e.g., 'max-num-of-symbol-per-slot') indicating the maximum number of symbols per slot supported by the RU (220). In one example, at 15 kHz subcarrier spacing, if the parameter (e.g., 'max-num-of-symbol-per-slot') indicates 2, the parameter (e.g., 'max-num-of-symbol-per-frame') may indicate a value less than 40.

[0103] In one embodiment, a parameter (e.g., 'min / max-supported-srs-sinr-reference level') may indicate a range of signal-to-interference plus noise ratio (SINR) reference levels supported by the RU (220). For example, the parameter may indicate a maximum reference level and a minimum reference level. For example, the SINR reference level may correspond to a scaling value for expressing the SINR as an integer. For example, at the maximum reference level, the SINR may be quantized (or sampled) at intervals of a first scaling value (e.g., 5). For example, at the minimum reference level, the SINR may be quantized (or sampled) at intervals of a second scaling value (e.g., 1).

[0104] In operation 602, the RU may receive RU configuration information from the DU (210). In one embodiment, the RU (220) may receive a second management plane message including the RU configuration information from the DU (210). For example, the RU configuration information may include a parameter indicating whether SRS channel estimation by the RU (220) is activated (e.g., 'srs-ce-activation'), a parameter indicating an SINR reference level used for SRS channel estimation by the RU (220) (e.g., 'srs-sinr-reference-level'), or a combination thereof. In one example, the RU configuration information may be defined according to [Table 2] below.

[0105] M-plane parametersTypeRangesrs-ce-activationBooleanTRUE, FALSEsrs-sinr-reference-level

[0106] In one embodiment, a parameter (e.g., 'srs-ce-activation') may indicate activation of SRS channel estimation by the RU (220). In one example, the parameter may be set to 'true' to indicate activation of SRS channel estimation by the RU (220). For example, the parameter may indicate deactivation of SRS channel estimation by the RU (220). In one example, the parameter may be set to 'false' to indicate deactivation of SRS channel estimation by the RU (220).

[0107] In one embodiment, a parameter (e.g., 'srs-sinr-reference-level') may indicate an SINR reference level used for SRS channel estimation by the RU (220). For example, the parameter may indicate an SRS reference level selected by the DU (210) from a range of values ​​indicated by a parameter (e.g., 'min / max-supported-srs-sinr-reference level') of the RU capability information.

[0108] Fig. 7 illustrates an example of control plane signaling for SRS channel estimation. As described in Fig. 4, SRS (sounding reference signal) channel estimation (CE) may be performed by either the DU (210) or the RU (220) depending on functional separation. In Fig. 7, operations are described when SRS channel estimation is performed by the RU (220) depending on functional separation (e.g., the sixth functional separation (430) and the seventh functional separation (440)).

[0109] Referring to FIG. 7, in operation 701, the RU (220) may receive SRS setup information from the DU (210). In one embodiment, the RU (220) may receive a first control plane (C-plane) message including the SRS setup information from the DU (210). For example, the SRS setup information may include first section type information (e.g., section type X (900) of FIG. 9), first section extension information (e.g., section extension A (1000) of FIG. 10), second section extension information (e.g., section extension B (1100) of FIG. 11), or a combination thereof.

[0110] In one embodiment, the first section type information (e.g., section type X (900) of FIG. 9) includes a parameter for a section identifier (e.g., 'sectionId'), a parameter for a resource block (RB) (e.g., 'rb'), a parameter for a symbol number increase command (e.g., 'symbInc'), a parameter indicating a starting physical resource block (PRB) (e.g., 'startPrbc'), a parameter indicating the number of PRBs (e.g., 'numPrbc'), a parameter indicating a comb type (e.g., 'csCombType'), a parameter indicating a sequence group number (e.g., 'u'), a parameter indicating a sequence number (e.g., 'v'), a parameter indicating a resource element (RE) offset (e.g., 'reOffset'), a parameter indicating a cyclic shift (e.g., 'cs'), a parameter for an identifier of a terminal (120) (e.g., 'ueId'), a parameter indicating an SRS repetition index (e.g., 'repetitionIdx'), a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor'), or a combination thereof.

[0111] In one embodiment, a parameter for a section identifier (e.g., 'sectionId') may be used to identify an individual data section described by a data section description within a first control plane message. For example, the parameter may be used to map a user plane (U-plane) data section to a first control plane message associated with the data.

[0112] In one embodiment, a parameter for an RB (e.g., 'rb') may indicate whether every RB is used or every other RB is used. For example, the parameter may be set to '0' to indicate that all RBs are used. For example, the parameter may be set to '1' to indicate that every other RB is used. In one example, if the parameter is 1, a parameter indicating a starting PRB (e.g., 'startPrbc') is 1, and a parameter indicating the number of PRBs (e.g., 'numPrbc') is 3, then the RBs that are used are 1, 3, and 5.

[0113] In one embodiment, a parameter indicating a comb type (e.g., 'csCombType') may indicate a comb size. For example, the comb size may correspond to the subcarrier spacing of an SRS transmitted by the terminal (120). For example, if the comb size is 2, the terminal (120) may transmit an SRS every two subcarriers. In one example, the comb size may be one of 2, 4, or 8. In one example, the parameter indicating the comb type ('csCombType') may be defined according to [Table 3] below.

[0114] csCombTypeRemarks00bComb size: 2, CS count (maximum): 801bComb size: 4, CS count (maximum): 1210bComb size: 8, CS count (maximum): 611breserved

[0115] In one embodiment, a parameter indicating a sequence group number (e.g., 'u') may indicate a group of SRS sequences. For example, an SRS sequence may be generated based on one of a plurality of groups. For example, a parameter indicating a sequence group number (e.g., 'u') may indicate one of the plurality of groups. In one example, the plurality of groups may include 30 groups. In one example, a parameter indicating a sequence group number (e.g., 'u') may be indicated by 5 bits. For example, a group may include one base sequence having a length in a first range (e.g., 60 or less) and two base sequences having lengths in a second range (e.g., greater than 60). In one embodiment, a parameter indicating a sequence number (e.g., 'v') may indicate a base sequence in the group. For example, one of the two base sequences having a length in the second range of the group may be indicated by the parameter indicating a sequence number (e.g., 'v'). In one example, a parameter representing a sequence number (e.g. 'v') can be represented by 1 bit.

[0116] In one embodiment, a parameter indicating an RE offset (e.g., 'reOffset') may indicate the number of REs offset for the transmission comb from a PRB indicated by a parameter indicating a starting PRB (e.g., 'startPrbc').

[0117] In one embodiment, a parameter indicating a cyclic shift (e.g., 'cs') may indicate a cyclic shift value applied by the terminal (120) for SRS transmission. For example, the range of the cyclic shift value may vary depending on the comb size. In one example, when the comb size is 2, the cyclic shift value may be one of 0 to 7. In one example, when the comb size is 4, the cyclic shift value may be one of 0 to 11. In one example, when the comb size is 8, the cyclic shift value may be one of 0 to 5.

[0118] In one embodiment, a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120), information for indicating at least one antenna port among antenna ports of the terminal (120), or a combination thereof. In one example, in order to obtain channel information for each terminal (120), a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120). In one example, in order to obtain channel information for each antenna port of the terminal (120), a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120) and information for indicating at least one antenna port among a plurality of antenna ports of the terminal (120).

[0119] In one embodiment, a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor') may indicate the number of consecutive SRS repetition symbols within a slot. In one example, when the parameter indicates 4, SRSs may be repeatedly transmitted in four consecutive symbols (e.g., the 11th symbol, the 12th symbol, the 13th symbol, and the 14th symbol of the slot). In one example, when the parameter indicates 2, SRSs may be repeatedly transmitted in two consecutive symbols (e.g., the 13th symbol and the 14th symbol of the slot). In one example, the parameter may indicate a value of one of 1, 2, or 4. In another example, the parameter may indicate a value of one of 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, or 14.

[0120] In one embodiment, a parameter indicating an SRS repetition index (e.g., 'repetitionIdx') may indicate one SRS symbol among SRS symbols that are repeatedly transmitted within a slot. In one example, when 2 is indicated by a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor'), an SRS may be repeatedly transmitted in the 13th symbol and the 14th symbol of the slot. The parameter may indicate one of the SRS transmissions in the 13th symbol and the SRS transmission in the 14th symbol. For example, the RU (220) may identify repeatedly transmitted SRSs based on the parameter. For example, the RU (220) may perform SRS channel estimation based on the identified SRSs.

[0121] In one embodiment, the first section extension information (e.g., section extension A (1000) of FIG. 10) may include information about multiple terminals allocated to the same time-frequency resource as the terminal (120). For example, the terminal (120) may correspond to a terminal indicated by a parameter for a terminal identifier of the first section type information (e.g., 'ueId'). For example, multiple terminals may be allocated to the same time-frequency resource using a cyclic shift. For example, a parameter indicating a comb type allocated to the multiple terminals (e.g., 'csCombType'), a parameter indicating a sequence group number (e.g., 'u'), a parameter indicating a sequence number (e.g., 'v'), and a parameter indicating a RE (resource element) offset (e.g., 'reOffset') may be the same. For example, a parameter indicating a comb type allocated to the plurality of terminals (e.g., 'csCombType'), a parameter indicating a sequence group number (e.g., 'u'), a parameter indicating a sequence number (e.g., 'v'), and a parameter indicating a RE (resource element) offset (e.g., 'reOffset') may be indicated by the first section type information. For example, the first section extension information may include a parameter for an identifier of a second terminal different from the terminal (120) (e.g., '2nd ueId'), a parameter indicating a cyclic shift for the second terminal (e.g., 'cs (for 2nd ueId')), a parameter indicating an SRS repetition index for the second terminal (e.g., 'repetitionIdx (for 2nd ueId)'), a parameter indicating an SRS repetition factor for the second terminal (e.g., 'repetitionFactor (for 2nd ueId)'), or a combination thereof.

[0122] In one embodiment, the second section extension information (e.g., section extension B (1100) of FIG. 11) may include parameters for indicating PRBs of channel information to be reported to the DU (210). For example, the second section extension information may include parameters for indicating PRBs of channel information to be reported to the DU (210) from among the PRBs indicated by the parameters of the first section type information (e.g., 'startPrbc', 'numPrbc', 'reOffset', and 'csCombType'). For example, the second section extension information may include a parameter (e.g., 'startPrbcRpt') for indicating a start PRB of channel information reported by the RU (220), a parameter (e.g., 'numPrbcRpt') for indicating the number of PRBs of channel information reported by the RU (220), a parameter (e.g., 'ciPrbGroupSizeRpt') for indicating an interval between adjacent PRBs, or a combination thereof.

[0123] In one example, a parameter indicating a start PRB (e.g., 'startPrbcRpt') may indicate 1. A parameter indicating the number of PRBs (e.g., 'numPrbcRpt') may indicate 3. A parameter indicating an interval between PRBs (e.g., 'ciPrbGroupSizeRpt') may indicate 2. In the above case, the RU (220) may report channel information for PRBs corresponding to PRB index 1, PRB index 3, and PRB index 5 to the DU (210) in operation 703 described below. In a non-limiting example, the second section extension information may indicate frequency information of the channel information reported by the RU (220) using the PRB index. For example, the second section extension information may include parameters indicating the PRB index instead of the above parameters.

[0124] In operation 702, RU (220) can perform SRS channel estimation.

[0125] In one embodiment, the RU (220) may receive an SRS from the terminal (120). For example, the RU (220) may receive the SRS in PRBs indicated by parameters of the first section type information (e.g., 'startPrbc', 'numPrbc', 'reOffset', and 'csCombType'). For example, the RU (220) may perform SRS channel estimation based on the received SRS. For example, the RU (220) may generate (or identify, obtain) information about channel coefficients, information about SINR, information about time offset, or a combination thereof for the PRBs indicated by parameters of the first section type information (e.g., 'startPrbc', 'numPrbc', 'reOffset', and 'csCombType') based on the SRS channel estimation.

[0126] In operation 703, RU (220) can transmit channel information to DU (210).

[0127] In one embodiment, the RU (220) may transmit a second control plane message including channel information to the DU (210). For example, the channel information may be used by the DU (210) for scheduling for the terminal (120) (and / or the terminals indicated by the first section extension information). For example, the channel information may include second section type information (e.g., section type 6 (1210) of FIG. 12a), third section extension information (e.g., section extension C (1220) of FIG. 12b), fourth section extension information (e.g., section extension D (1230) of FIG. 12b), or a combination thereof.

[0128] In one embodiment, the second section type information (e.g., section type 6 (1210) of FIG. 12A) may include channel coefficients for PRBs indicated by parameters of the second section extension information (e.g., 'startPrbcRpt', 'numPrbcRpt', and 'ciPrbGroupSizeRpt'). For example, the RU (220) may identify PRBs based on the parameters of the second section extension information. For example, the RU (220) may identify channel coefficients corresponding to the PRBs among the channel information obtained based on the parameters of the first section type information (e.g., 'startPrbc' and 'numPrbc'). For example, the second section type information may include channel coefficients corresponding to the PRBs.

[0129] In one embodiment, the second section type information may include channel coefficients for consecutive PRBs indicated by parameters of the first section type information (e.g., 'startPrbc' and 'numPrbc'). For example, the first control plane message may not include second section extension information. For example, the RU (220) may identify channel coefficients for consecutive PRBs indicated by parameters of the first section type information when the second section extension information is not configured. For example, the second section type information may include channel coefficients for the consecutive PRBs. For example, the channel information may not include fifth section extension information (e.g., section extension 21) that includes a parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs.

[0130] In one embodiment, the third section extension information may include time offset information. For example, the time offset may include information for synchronization between a base station (e.g., DU (210) and / or RU (220)) and a terminal (e.g., terminal (120)). For example, the time offset may indicate a difference between an SRS transmission time by the terminal (120) and an SRS reception time by the RU (220). For example, the time offset information may be used to control a timing advance (TA) of the terminal (120). For example, the time offset information may include terminal-specific time offset information. For example, the time offset information may include antenna-specific time offset information of the terminal. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the second section extension information.

[0131] In one embodiment, the fourth section extension information may include SINR information. For example, the SINR information may indicate an SINR scaled into an integer based on a parameter for an SINR reference level obtained through the management plane (e.g., 'srs-sinr-reference-level'). For example, the SINR information may include SINR information per terminal. For example, the SINR information may include SINR information per antenna of the terminal. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the second section extension information.

[0132] In one embodiment, the channel information may further include fifth section extension information (e.g., section extension 21) including a parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs. For example, the value of the parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs may correspond to the value indicated by the parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs in the second section extension information. For example, the channel information may not include fifth section extension information (e.g., section extension 21) including a parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs when the parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs in the second section extension information indicates 1.

[0133] In operation 704, the RU (220) may determine a beamforming weight for downlink transmission. In one embodiment, the RU (220) may determine the beamforming weight based on channel information for PRBs indicated by parameters of the first section type information (e.g., 'startPrbc', 'numPrbc', 'reOffset', and 'csCombType'). In a non-limiting example, the RU (220) may determine the beamforming weight based on channel information for PRBs indicated by parameters of the second section extension information (e.g., 'startPrbcRpt', 'numPrbcRpt', and 'ciPrbGroupSizeRpt').

[0134] Fig. 8 illustrates an example of signaling between a DU and an RU for SRS channel estimation. As described in Fig. 4, SRS (sounding reference signal) channel estimation (CE) may be performed by either the DU (210) or the RU (220) depending on functional separation. In Fig. 8, signaling between the DU (210) and the RU (220) to enable SRS channel estimation by the RU (220) depending on functional separation (e.g., the sixth functional separation (430), the seventh functional separation (440)) is described. In the following embodiments, each operation may be performed sequentially, but is not necessarily performed sequentially. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0135] Referring to FIG. 8, in operation 801, a radio unit (RU) (220) may transmit a first management plane (M-plane) message to a DU (210). For example, the first management plane message may include RU capability information.

[0136] In one embodiment, the RU capability information includes a parameter indicating whether SRS channel estimation by the RU (220) is supported (e.g., 'srs-ce-supported'), a parameter indicating the maximum value of an SRS repetition factor supported by the RU (220) (e.g., 'max-supported-repetition-factor'), a parameter indicating the maximum number of terminals supported by the RU (220) (e.g., 'max-number-of-ues'), a parameter indicating a transmission comb supported by the RU (220) (e.g., 'transmission-comb'), a parameter indicating the number of cyclic shifts per SRS symbol supported by the RU (220) (e.g., 'supported-cs'), a parameter indicating the maximum number of symbols per slot supported by the RU (220) (e.g., 'max-num-of-symbol-per slot'), a parameter indicating the maximum number of symbols per frame supported by the RU (220) 'max-num-of-symbol-per-frame'), a parameter indicating the range of signal-to-interference plus noise ratio (SINR) reference levels supported by the RU (220) (e.g., 'min / max-supported-srs-sinr-reference-level'), or a combination thereof.

[0137] At operation 802, the RU (220) may receive a second management plane message from the DU (210). In one embodiment, the second management plane message may include RU configuration information.

[0138] In one embodiment, the RU configuration information may include a parameter indicating whether SRS channel estimation by the RU (220) is activated (e.g., 'srs-ce-activation'), a parameter indicating an SINR reference level used for SRS channel estimation by the RU (220) (e.g., 'srs-sinr-reference-level'), or a combination thereof.

[0139] In one embodiment, the RU (220) may activate the SRS channel estimation function by the RU (220) when the above parameter (e.g., 'srs-ce-activation') is set to 'true'. For example, the RU (220) may deactivate the SRS channel estimation function by the RU (220) when the above parameter (e.g., 'srs-ce-activation') is set to 'false'.

[0140] In operation 803, the RU (220) may receive a first control plane (C-plane) message from the DU (210). For example, the first control plane message may include first section type information (e.g., section type X (900) of FIG. 9), first section extension information (e.g., section extension A (1000) of FIG. 10), second section extension information (e.g., section extension B (1100) of FIG. 11), or a combination thereof.

[0141] In one embodiment, the first section type information may include a parameter for a section identifier (e.g., 'sectionId'), a parameter for a resource block (RB) (e.g., 'rb'), a parameter for a symbol number increment command (e.g., 'symbInc'), a parameter indicating a starting physical resource block (PRB) (e.g., 'startPrbc'), a parameter indicating the number of PRBs (e.g., 'numPrbc'), a parameter indicating a comb type (e.g., 'csCombType'), a parameter indicating a sequence group number (e.g., 'u'), a parameter indicating a sequence number (e.g., 'v'), a parameter indicating a resource element (RE) offset (e.g., 'reOffset'), a parameter indicating a cyclic shift (e.g., 'cs'), a parameter for an identifier of the terminal (120) (e.g., 'ueId'), a parameter indicating an SRS repetition index (e.g., 'repetitionIdx'), a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor'), or a combination thereof.

[0142] In one embodiment, the first section extension information may include information about multiple terminals allocated to the same time-frequency resource. For example, multiple terminals may be allocated to the same time-frequency resource using a cyclic shift. For example, the first section extension information may include a parameter for an identifier of a second terminal different from terminal (120) (e.g., '2nd ueId'), a parameter indicating a cyclic shift for the second terminal (e.g., 'cs (for 2nd ueId')), a parameter indicating an SRS repetition index for the second terminal (e.g., 'repetitionIdx (for 2nd ueId)'), a parameter indicating an SRS repetition factor for the second terminal (e.g., 'repetitionFactor (for 2nd ueId)'), or a combination thereof.

[0143] In one embodiment, the second section extension information may include a parameter indicating a start PRB of channel information reported by RU (220) (e.g., 'startPrbcRpt'), a parameter indicating the number of PRBs of channel information reported by RU (220) (e.g., 'numPrbcRpt'), a parameter indicating a spacing between adjacent PRBs (e.g., 'ciPrbGroupSizeRpt'), or a combination thereof.

[0144] In operation 804, the RU (220) may transmit a second control plane message to the DU (210). For example, the second control plane message may include second section type information (e.g., section type 6 (1210) of FIG. 12a), third section extension information (e.g., section extension C (1220) of FIG. 12b), fourth section extension information (e.g., section extension D (1230) of FIG. 12b), or a combination thereof.

[0145] In one embodiment, the second section type information may include channel coefficients for PRBs indicated by the second section extension information. For example, the RU (220) may identify PRBs based on parameters (e.g., 'startPrbcRpt', 'numPrbcRpt', and 'ciPrbGroupSizeRpt') of the second section extension information. For example, the RU (220) may identify channel coefficients corresponding to the PRBs among the acquired channel information based on parameters (e.g., 'startPrbc' and 'numPrbc') of the first section type information. For example, the second section type information may include channel coefficients corresponding to the PRBs.

[0146] In one embodiment, the second section type information may include channel coefficients for consecutive PRBs indicated by the first section type information. For example, the first control plane message (803) may not include second section extension information. For example, the RU (220) may identify channel coefficients for consecutive PRBs indicated by parameters of the first section type information (e.g., 'startPrbc' and 'numPrbc') when the second section extension information is not configured. For example, the second section type information may include channel coefficients for the consecutive PRBs.

[0147] In one embodiment, the third section extension information may include time offset information. For example, the time offset may include information for synchronization between a base station (e.g., DU (210) and / or RU (220)) and a terminal (e.g., terminal (120)). For example, the time offset may indicate a difference between an SRS transmission time by terminal (120) and an SRS reception time by RU (220). For example, the time offset information may be used to control the timing advance (TA) of terminal (120). For example, the time offset information may include terminal-specific time offset information. For example, the time offset information may include antenna-specific time offset information of the terminal. In the present disclosure, the third section extension information is described as being one, but the present disclosure is not limited thereto. For example, the number of third section extension information may correspond to the number of terminal identifiers included in the first section extension information. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the second section extension information.

[0148] In one embodiment, the fourth section extension information may include signal-to-interference plus noise ratio (SINR) information. For example, the SINR information may indicate an SINR scaled into an integer based on a parameter (e.g., 'srs-sinr-reference-level') for an SINR reference level obtained through the management plane. For example, the SINR information may include SINR information per terminal. In another example, the SINR information may include SINR information per antenna of the terminal. In the present disclosure, the fourth section extension information is described as being one, but the present disclosure is not limited thereto. For example, the number of fourth section extension information may correspond to the number of terminal identifiers included in the first section extension information. In a non-limiting example, the SINR information may include SINR information per antenna port of the terminal. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by the parameters of the first section type information. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the second section extension information.

[0149] In one embodiment, the second control plane message may further include fifth section extension information (e.g., section extension 21) including a parameter (e.g., 'ciPrbGroupoSize') indicating a spacing between adjacent PRBs. For example, the value of the parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs may correspond to a value indicated by a parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs in the second section extension information.

[0150] In one embodiment, the second control plane message may not include fifth section extension information (e.g., section extension 21) that includes a parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs, if the parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs of the second section extension information indicates 1.

[0151] Fig. 9 illustrates an example of section type information of a control plane message for SRS channel estimation. Section type X (900) illustrated in Fig. 9 illustrates information elements included in a control plane (C-plane) message. Meanwhile, section type X of Fig. 9 is merely an example, and section type X may be referred to by various names. In one example, section type X may be referred to as section type 9.

[0152] Referring to 901 of FIG. 9, the section type information (e.g., section type X) of the control plane (C-plane) message includes a parameter for the section identifier (e.g., 'sectionId'), a parameter for the resource block (RB) (e.g., 'rb'), a parameter for the symbol number increase command (e.g., 'symbInc'), a parameter indicating the start physical resource block (PRB) (e.g., 'startPrbc'), a parameter indicating the number of PRBs (e.g., 'numPrbc'), a parameter indicating the comb type (e.g., 'csCombType'), a parameter indicating the sequence group number (e.g., 'u'), a parameter indicating the sequence number (e.g., 'v'), a parameter indicating the RE (resource element) offset (e.g., 'reOffset'), a parameter indicating a cyclic shift (e.g., 'cs'), a parameter for the identifier of the terminal (120) (e.g., 'ueId'), a parameter indicating the SRS repetition index (e.g., 'repetitionIdx'), and an SRS repetition It may contain parameters indicating factors (e.g. 'repetitionFactor'), or combinations thereof.

[0153] In one embodiment, a parameter for a section identifier (e.g., 'sectionId') may be used to identify an individual data section described by a data section description within a first control plane message. For example, the parameter may be used to map a user plane (U-plane) data section to a first control plane message associated with the data.

[0154] In one embodiment, a parameter for an RB (e.g., 'rb') may indicate whether every RB is used or every other RB is used. For example, the parameter may be set to '1' to indicate that all RBs are used. For example, the parameter may be set to '0' to indicate that all other RBs are used. In one example, if the parameter is 1, a parameter indicating a starting PRB (e.g., 'startPrbc') is 1, and a parameter indicating the number of PRBs (e.g., 'numPrbc') is 3, then the RBs that are used are 1, 3, and 5.

[0155] In one embodiment, a parameter indicating a comb type (e.g., 'csCombType') may indicate a comb size. For example, the comb size may correspond to the subcarrier spacing of an SRS transmitted by the terminal (120). For example, if the comb size is 2, the terminal (120) may transmit an SRS every two subcarriers. In one example, the comb size may be one of 2, 4, or 8.

[0156] In one embodiment, a parameter indicating a sequence group number (e.g., 'u') may indicate a group of SRS sequences. For example, an SRS sequence may be generated based on one of a plurality of groups. For example, a parameter indicating a sequence group number (e.g., 'u') may indicate one of the plurality of groups. In one example, the plurality of groups may include 30 groups. In one example, a parameter indicating a sequence group number (e.g., 'u') may be indicated by 5 bits. For example, a group may include one base sequence having a length in a first range (e.g., 60 or less) and two base sequences having lengths in a second range (e.g., greater than 60). In one embodiment, a parameter indicating a sequence number (e.g., 'v') may indicate a base sequence in the group. For example, one of the two base sequences having a length in the second range of the group may be indicated by the parameter indicating a sequence number (e.g., 'v'). In one example, a parameter representing a sequence number (e.g. 'v') can be represented by 1 bit.

[0157] In one embodiment, a parameter indicating an RE offset (e.g., 'reOffset') may indicate the number of REs offset for the transmission comb from a PRB indicated by a parameter indicating a starting PRB (e.g., 'startPrbc').

[0158] In one embodiment, a parameter indicating a cyclic shift (e.g., 'cs') may indicate a cyclic shift value applied by the terminal (120) for SRS transmission. For example, the range of the cyclic shift value may vary depending on the comb size. In one example, when the comb size is 2, the cyclic shift value may be one of 0 to 7. In one example, when the comb size is 4, the cyclic shift value may be one of 0 to 11. In one example, when the comb size is 8, the cyclic shift value may be one of 0 to 5.

[0159] In one embodiment, a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120), information for indicating at least one antenna port among antenna ports of the terminal (120), or a combination thereof. In one example, in order to obtain channel information for each terminal (120), a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120). In one example, in order to obtain channel information for each antenna port of the terminal (120), a parameter (e.g., 'ueId') for an identifier of a terminal (120) may include information for indicating the terminal (120) and information for indicating at least one antenna port among a plurality of antenna ports of the terminal (120).

[0160] In one embodiment, a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor') may indicate the number of consecutive SRS repetition symbols within a slot. In one example, when the parameter indicates 4, SRSs may be repeatedly transmitted in four consecutive symbols (e.g., the 11th symbol, the 12th symbol, the 13th symbol, and the 14th symbol of the slot). In one example, when the parameter indicates 2, SRSs may be repeatedly transmitted in two consecutive symbols (e.g., the 13th symbol and the 14th symbol of the slot). In one example, the parameter may indicate a value of one of 1, 2, or 4. In another example, the parameter may indicate a value of one of 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, or 14.

[0161] In one embodiment, a parameter indicating an SRS repetition index (e.g., 'repetitionIdx') may indicate one SRS symbol among SRS symbols that are repeatedly transmitted within a slot. In one example, when 2 is indicated by a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor'), an SRS may be repeatedly transmitted in the 13th symbol and the 14th symbol of the slot. The parameter may indicate one of the SRS transmissions in the 13th symbol and the SRS transmission in the 14th symbol. For example, the RU (220) may identify repeatedly transmitted SRSs based on the parameter. For example, the RU (220) may perform SRS channel estimation based on the identified SRSs.

[0162] Fig. 10 illustrates an example of section extension information of a control plane message for SRS channel estimation. Section extension A (1000) illustrated in Fig. 10 illustrates information elements included in a control plane (C-plane) message. Meanwhile, section extension A (1000) of Fig. 10 is merely an example, and section extension A (1000) may be referred to by various names. In one example, section extension A (1000) may be referred to as section extension 24.

[0163] A control plane message (e.g., the first control plane message (803) of FIG. 8) may include a section type X (900). The control plane message may further include section extensions in addition to the section type X (900). For example, the control plane message may include a section type X (900), a section extension A (1000), and a section extension B (1100). When the control plane message further includes section extension A (1000) and section extension B (1100), section extension A (1000) and section extension B (1100) may be placed at 902 of FIG. 9.

[0164] Referring to FIG. 10, section extension A (1000) may include information about a plurality of terminals allocated to the same time-frequency resource as terminal (120). For example, terminal (120) may correspond to a terminal indicated by a parameter ('ueId') for a terminal identifier of section type X (900). For example, the number of multiple terminals of section extension A (1000) may be indicated by a parameter ('numCsExt').

[0165] In one embodiment, section extension information A (1000) may include a parameter for an identifier of each terminal, a parameter indicating a cyclic shift of each terminal, a parameter indicating an SRS repetition index of each terminal, and a parameter indicating a repetition factor of each terminal.

[0166] In one example, information (1001) for the second terminal of section extension information A (1000) may include a parameter for an identifier of the second terminal ('2nd ueId'), a parameter indicating a cyclic shift for the second terminal ('cs (for 2nd ueId)'), a parameter indicating an SRS repetition index for the second terminal ('repetitionIdx (for 2nd ueId)'), and a parameter indicating an SRS repetition factor for the second terminal ('repetitionFactor (for 2nd ueId)').

[0167] In one example, information (1002) for a third terminal of section extension information A (1000) may include a parameter for an identifier of the third terminal ('3rd ueId'), a parameter indicating a cyclic shift for the third terminal ('cs (for 3rd ueId)'), a parameter indicating an SRS repetition index for the third terminal ('repetitionIdx (for 3rd ueId)'), and a parameter indicating an SRS repetition factor for the third terminal ('repetitionFactor (for 3rd ueId)').

[0168] Fig. 11 illustrates an example of section extension information of a control plane message for SRS channel estimation. Section extension B (1100) illustrated in Fig. 11 illustrates information elements included in a control plane (C-plane) message. Meanwhile, section extension B (1100) of Fig. 11 is merely an example, and section extension B (1100) may be referred to by various names. In one example, section extension B (1100) may be referred to as section extension 25.

[0169] A control plane message (e.g., the first control plane message (803) of FIG. 8) may include a section type X (900). The control plane message may further include section extensions in addition to the section type X (900). For example, the control plane message may include a section type X (900), a section extension A (1000), and a section extension B (1100). When the control plane message further includes section extension A (1000) and section extension B (1100), section extension A (1000) and section extension B (1100) may be placed at 902 of FIG. 9.

[0170] Referring to FIG. 11, section extension B (1100) may include a parameter ('startPrbcRpt') (1101) indicating a start PRB of channel information reported from RU (220) to DU (210), a parameter ('numPrbcRpt') (1102) indicating the number of PRBs of the channel information, and a parameter ('ciPrbGroupSizeRpt') (1103) indicating an interval between PRBs of the channel information.

[0171] In one example, a parameter indicating a start PRB ('startPrbcRpt') may indicate 1. In one example, a parameter indicating the number of PRBs ('numPrbcRpt') may indicate 3. In one example, a parameter indicating an interval between PRBs ('ciPrbGroupSizeRpt') may indicate 2. In this case, channel information reported from the RU (220) to the DU (210) may correspond to channel information obtained based on PRBs of PRB index 1, PRB index 3, and PRB index 5.

[0172] Figure 12a illustrates an example of section type information of a control plane message for SRS channel estimation. Figure 12a illustrates information elements according to section type 6 included in a control plane (C-plane) message. For example, a control plane message (e.g., the second control plane message (804) of Figure 8) may include section type 6.

[0173] In one embodiment, section type 6 (1200) may include channel coefficients for PRBs indicated by parameters of section extension B (1100). For example, the channel coefficients may include channel coefficients for each antenna of the terminal.

[0174] In one example, a first PRB (e.g., PRB index 3) and a second PRB (e.g., PRB index 5) may be indicated by parameters (e.g., 'startPrbcRpt', 'numPrbcRpt', and 'ciPrbGroupSizeRpt') of section extension B (1100). In one example, the terminal (120) may include a first antenna port and a second antenna port. In one example, the channel coefficients for each antenna of the terminal (120) may include an in-phase channel coefficient for the first PRB and the first antenna port, a quadrature channel coefficient for the first PRB and the first antenna port, an in-phase channel coefficient for the first PRB and the second antenna port, a quadrature channel coefficient for the first PRB and the second antenna port, an in-phase channel coefficient for the second PRB and the first antenna port, a quadrature phase channel coefficient for the second PRB and the first antenna port, an in-phase channel coefficient for the second PRB and the second antenna port, and a quadrature phase channel coefficient for the second PRB and the second antenna port.

[0175] As described above, the RU (220) can report channel coefficients to the DU (210) using section type 6 (1200) within the range of PRBs indicated by the parameters of section extension B (1100). Since the channel coefficients are reported within the range of PRBs indicated by the parameters of section extension B (1100), the fronthaul overhead can be reduced.

[0176] Fig. 12b illustrates an example of section extension information of a control plane message for SRS channel estimation. Section extension C (1220) and section extension D (1230) illustrated in Fig. 12b illustrate information elements included in a control plane (C-plane) message. Meanwhile, section extension C (1220) and section extension D (1230) of Fig. 12b are merely examples, and section extension C (1220) and section extension D (1230) may be referred to by various names. In one example, section extension C (1220) may be referred to as section extension 26. In one example, section extension D (1220) may be referred to as section extension 27.

[0177] In one embodiment, a control plane message (e.g., the second control plane message (804) of FIG. 8) may include section type 6 (1210). The control plane message may further include section extensions in addition to section type 6 (1210). For example, the control plane message may include section type 6 (1210), section extension C (1220), and section extension D (1230). For example, if the control plane message further includes section extension C (1220) and section extension D (1230), section extension C (1220) and section extension D (1230) may be placed at 1211 of FIG. 12A.

[0178] In one embodiment, section extension C (1220) may include information (1221) about a time offset for the terminal (120). For example, the time offset may include information for synchronization between a base station (e.g., DU (210) and RU (220)) and the terminal (120). For example, the time offset may indicate a difference between an SRS transmission time by the terminal (120) and an SRS reception time by the RU (220). For example, the time offset may be used to control a timing advance (TA) of the terminal (120). In the present disclosure, although the section extension C (1220) is described as being single, the present disclosure is not limited thereto. For example, a control plane message (e.g., the second control plane message (804) of FIG. 8) may further include section extensions corresponding to the number of terminal identifiers included in section extension A (1000). In a non-limiting example, the information about the time offset may include information about the time offset for each antenna port of the terminal (120). In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the second section extension information.

[0179] In one embodiment, section extension D (1230) may include information (1231) about a signal-to-interference plus noise ratio (SINR) for the terminal (120). For example, the SINR information may indicate an SINR scaled to an integer based on a parameter (e.g., 'srs-sinr-reference-level') obtained by a management plane message (e.g., the second management plane message (802) of FIG. 8). In the present disclosure, although there is a single section extension D (1230), the present disclosure is not limited thereto. For example, a control plane message (e.g., the second control plane message (804) of FIG. 8) may further include section extensions corresponding to the number of terminal identifiers included in section extension A (1000). In a non-limiting example, the information about SINR may include information about an SINR per antenna port of the terminal. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the second section extension information.

[0180] Figure 13 is a flowchart illustrating the operation of a DU for SRS channel estimation. In the following embodiments, each operation may be performed sequentially, but is not necessarily sequential. For example, the order of each operation may be changed, and at least two operations may be performed in parallel.

[0181] Referring to FIG. 13, in operation 1301, DU (210) may receive RU capability information from RU (220). In one embodiment, DU (210) may receive a first management plane (M-plane) message including RU capability information from RU (220).

[0182] In one embodiment, the RU capability information includes a parameter indicating whether SRS channel estimation by the RU (220) is supported (e.g., 'srs-ce-supported'), a parameter indicating the maximum value of an SRS repetition factor supported by the RU (220) (e.g., 'max-supported-repetition-factor'), a parameter indicating the maximum number of terminals supported by the RU (220) (e.g., 'max-number-of-ues'), a parameter indicating a transmission comb supported by the RU (220) (e.g., 'transmission-comb'), a parameter indicating the number of cyclic shifts per SRS symbol supported by the RU (220) (e.g., 'supported-cs'), a parameter indicating the maximum number of symbols per slot supported by the RU (220) (e.g., 'max-num-of-symbol-per slot'), a parameter indicating the maximum number of symbols per frame supported by the RU (220) 'max-num-of-symbol-per-frame'), a parameter indicating the range of signal-to-interference plus noise ratio (SINR) reference levels supported by the RU (220) (e.g., 'min / max-supported-srs-sinr-reference-level'), or a combination thereof.

[0183] In operation 1302, DU (210) may transmit RU configuration information to RU (220). In one embodiment, DU (210) may transmit a second management plane message including RU configuration information to RU (220).

[0184] In one embodiment, the RU configuration information may include a parameter indicating whether SRS channel estimation by the RU (220) is activated (e.g., 'srs-ce-activation'), a parameter indicating an SINR reference level used for SRS channel estimation by the RU (220) (e.g., 'srs-sinr-reference-level'), or a combination thereof.

[0185] In operation 1303, the DU (210) may transmit SRS setup information to the RU (220). In one embodiment, the DU (210) may transmit a first control plane (C-plane) message including the SRS setup information to the RU (220). For example, the SRS setup information may include first section type information (e.g., section type X (900) of FIG. 9), first section extension information (e.g., section extension A (1000) of FIG. 10), second section extension information (e.g., section extension B (1100) of FIG. 11), or a combination thereof.

[0186] In one embodiment, the first section type information may include a parameter for a section identifier (e.g., 'sectionId'), a parameter for a resource block (RB) (e.g., 'rb'), a parameter for a symbol number increment command (e.g., 'symbInc'), a parameter indicating a starting physical resource block (PRB) (e.g., 'startPrbc'), a parameter indicating the number of PRBs (e.g., 'numPrbc'), a parameter indicating a comb type (e.g., 'csCombType'), a parameter indicating a sequence group number (e.g., 'u'), a parameter indicating a sequence number (e.g., 'v'), a parameter indicating a resource element (RE) offset (e.g., 'reOffset'), a parameter indicating a cyclic shift (e.g., 'cs'), a parameter for an identifier of the terminal (120) (e.g., 'ueId'), a parameter indicating an SRS repetition index (e.g., 'repetitionIdx'), a parameter indicating an SRS repetition factor (e.g., 'repetitionFactor'), or a combination thereof.

[0187] In one embodiment, the first section extension information may include information about multiple terminals allocated to the same time-frequency resource. For example, multiple terminals may be allocated to the same time-frequency resource using a cyclic shift. For example, the first section extension information may include a parameter for an identifier of a second terminal different from terminal (120) (e.g., '2nd ueId'), a parameter indicating a cyclic shift for the second terminal (e.g., 'cs (for 2nd ueId')), a parameter indicating an SRS repetition index for the second terminal (e.g., 'repetitionIdx (for 2nd ueId)'), a parameter indicating an SRS repetition factor for the second terminal (e.g., 'repetitionFactor (for 2nd ueId)'), or a combination thereof.

[0188] In one embodiment, the second section extension information may include a parameter indicating a start PRB of channel information reported by RU (220) (e.g., 'startPrbcRpt'), a parameter indicating the number of PRBs of channel information reported by RU (220) (e.g., 'numPrbcRpt'), a parameter indicating a spacing between adjacent PRBs (e.g., 'ciPrbGroupSizeRpt'), or a combination thereof.

[0189] In operation 1304, DU (210) may receive channel information from RU (220). In one embodiment, DU (210) may receive a second control plane message including the channel information from RU (220). For example, the channel information may be used for scheduling for terminal (120) (and / or multiple terminals indicated by the first section extension information). For example, the channel information may include second section type information (e.g., section type 6 (1210) of FIG. 12a), third section extension information (e.g., section extension C (1220) of FIG. 12b), fourth section extension information (e.g., section extension D (1230) of FIG. 12b), or a combination thereof.

[0190] In one embodiment, the second section type information may include channel coefficients for PRBs indicated by parameters of the second section extension information. For example, the second section type information may include channel coefficients for at least one PRB indicated by the second section extension information among the PRBs indicated by the first section type information.

[0191] In one embodiment, the second section type information may include channel coefficients for PRBs indicated by the parameters of the first section type information. For example, if the first control plane message does not include second section extension information, the second section type information may include channel coefficients for PRBs indicated by the parameters of the first section type information.

[0192] In one embodiment, the third section extension information may include information about a time offset for the terminal (120). For example, the time offset may include information for synchronization between a base station (e.g., DU (210) and RU (220)) and the terminal (120). For example, the time offset may indicate a difference between an SRS transmission time by the terminal (120) and an SRS reception time by the RU (220). For example, the time offset may be used to control a timing advance (TA) of the terminal (120). In the present disclosure, the third section extension information is described as being one, but the present disclosure is not limited thereto. For example, the second control plane message may further include section extensions corresponding to the number of terminal identifiers included in the first section extension information. In a non-limiting example, the information about the time offset may include information about a time offset for each antenna port of the terminal (120). In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the time offset information may include time offset information for PRBs indicated by parameters of the second section extension information.

[0193] In one embodiment, the fourth section extension information may include information about a signal-to-interference plus noise ratio (SINR) for the terminal (120). For example, the SINR information may indicate an SINR scaled into an integer based on a parameter (e.g., 'srs-sinr-reference-level') obtained by the second management plane message. In the present disclosure, the fourth section extension information is described as being one, but the present disclosure is not limited thereto. For example, the second control plane message may further include section extensions corresponding to the number of terminal identifiers included in the first section extension information. In a non-limiting example, the information about the SINR may include information about the SINR for each antenna port of the terminal. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the first section type information. In a non-limiting example, the SINR information may include SINR information for PRBs indicated by parameters of the second section extension information.

[0194] In one embodiment, the second control plane message may further include fifth section extension information (e.g., section extension 21) including a parameter (e.g., 'ciPrbGroupoSize') indicating a spacing between adjacent PRBs. For example, the value of the parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs may correspond to the value indicated by the parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs in the second section extension information. For example, the second control plane message may not include fifth section extension information (e.g., section extension 21) including a parameter (e.g., 'ciPrbGroupSize') indicating a spacing between adjacent PRBs when the parameter (e.g., 'ciPrbGroupSizeRpt') indicating a spacing between adjacent PRBs in the second section extension information indicates 1.

[0195] Figure 14 shows an example of SRS channel estimation according to RU capability.

[0196] Referring to FIG. 14, according to one embodiment, the RU (1420) may support an SRS channel estimation function. For example, the RU (1420) may transmit a first management plane message (1421) including RU capability information in which the parameter ('srs-ce-supported') is set to 'true' to the DU (1410). For example, the RU (1420) may receive a second management plane message (1422) including RU configuration information in which the parameter ('srs-ce-activation') is set to 'true'. For example, the RU (1420) may perform SRS channel estimation based on the parameter ('srs-ce-activation') set to 'true'.

[0197] In one embodiment, the RU (1430) may support an SRS channel estimation function. For example, the RU (1430) may transmit a first management plane message (1431) including RU capability information with a parameter ('srs-ce-supported') set to 'true' to the DU (1410). For example, the RU (1430) may receive a second management plane message (1432) including RU configuration information with a parameter ('srs-ce-activation') set to 'false'. For example, the RU (1430) may transmit an SRS received from the terminal (120) to the DU (1410). For example, the DU (1410) may perform SRS channel estimation based on the received SRS.

[0198] In one embodiment, the RU (1440) may not support the SRS channel estimation function. For example, the RU (1440) may transmit a first management plane message (1441) including RU capability information with the parameter ('srs-ce-supported') set to 'false' to the DU (1410). For example, the RU (1440) may receive a second management plane message (1442) including RU configuration information with the parameter ('srs-ce-activation') set to 'false'. For example, the RU (1440) may transmit an SRS received from the terminal (120) to the DU (1410). For example, the DU (1410) may perform SRS channel estimation based on the received SRS.

[0199] In one embodiment, the RU (1450) may transmit a first management plane message (1451) to the DU (1410) that includes a parameter ('srs-ce-supported'). For example, the parameter ('srs-ce-supported') may be invalid (e.g., N / A). For example, the RU (1450) may receive a second management plane message (1452) that includes RU configuration information in which the parameter ('srs-ce-activation') is set to 'false'. For example, the RU (1450) may transmit an SRS received from the terminal (120) to the DU (1410). For example, the DU (1410) may perform SRS channel estimation based on the received SRS.

[0200] A base station (a distributed unit (DU) and / or a radio unit (RU)) according to the present disclosure can provide signaling that enables SRS channel estimation by the RU. In addition, the base station according to the present disclosure can reduce fronthaul overhead by enabling SRS channel estimation by the RU. In addition, the base station according to the present disclosure can reduce processing delay for channel information based beamforming (CIBF) (e.g., SRS-based multiple input multiple output (MIMO)) by enabling channel estimation by the RU. In addition, the base station according to the present disclosure can improve CIBF performance by providing signaling that enables channel estimation by the RU.

[0201] The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, 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 above description.

[0202] The method performed by the radio unit (RU) as described above may include receiving, from a distributed unit (DU), a control plane message via a fronthaul interface, the control plane message including section information for sounding reference signal (SRS) setup and section extension information indicating a range of physical resource blocks (PRBs) for reporting SRS channel estimation. The method may include receiving SRSs from a terminal on a plurality of PRBs. The method may include identifying, based on channel estimation of the SRSs, at least one channel coefficient corresponding to the range of the PRBs indicated by the section extension information. The method may include transmitting, to the DU, a message including information on the at least one channel coefficient via the fronthaul interface.

[0203] For example, the section extension information may include a parameter indicating a starting PRB within the plurality of PRBs, a parameter indicating the number of PRBs, and a parameter indicating a PRB interval between the PRBs.

[0204] For example, the method may further include transmitting, to the DU via the fronthaul interface, a first management plane message including capability information of the RU associated with the SRS channel estimation. The capability information may include a parameter indicating whether the RU supports the SRS channel estimation, a parameter indicating a repetition factor supported by the RU, a parameter indicating a maximum number of UEs supported by the RU, a parameter indicating a transmission comb size, a parameter indicating a number of cyclic shifts (CSs) supported by the RU, a parameter indicating a maximum number of symbols in a slot supported by the RU, a parameter indicating a maximum number of symbols in a frame supported by the RU, a parameter indicating a range of a reference level of a signal-to-interference plus noise ratio (SINR) supported by the RU, or a combination thereof.

[0205] For example, the method may further include receiving, from the DU via the fronthaul interface, a second management plane message including configuration information for the SRS channel estimation. The configuration information may include a parameter indicating whether the SRS channel estimation by the RU is activated and a parameter indicating a reference level of SINR.

[0206] For example, the section information may include a parameter indicating a repetition factor configured for the SRS and a parameter indicating a repetition index of a symbol of the SRS.

[0207] A method performed by a distributed unit (DU) as described above may include transmitting a control plane message to an RU via a fronthaul interface, the control plane message including section information for SRS setup and section extension information indicating a range of PRBs for reporting SRS channel estimation. The method may include receiving from the RU via the fronthaul interface a message including information on at least one channel coefficient corresponding to the range of the PRBs indicated by the section extension information. The at least one channel coefficient may be associated with the SRS channel estimation in the RU.

[0208] For example, the section extension information may include a parameter indicating a starting PRB within a plurality of PRBs for receiving SRSs, a parameter indicating the number of the PRBs, and a parameter indicating a PRB interval between the PRBs.

[0209] For example, the method may further include receiving, from the RU via the fronthaul interface, a first management plane message including capability information of the RU associated with the SRS channel estimation. The capability information may include a parameter indicating whether the RU supports the SRS channel estimation, a parameter indicating a repetition factor supported by the RU, a parameter indicating a maximum number of UEs supported by the RU, a parameter indicating a transmission comb size, a parameter indicating a number of cyclic shifts (CSs) supported by the RU, a parameter indicating a maximum number of symbols in a slot supported by the RU, a parameter indicating a maximum number of symbols in a frame supported by the RU, a parameter indicating a range of a reference level of a signal-to-interference plus noise ratio (SINR) supported by the RU, or a combination thereof.

[0210] For example, the method may further include transmitting a second management plane message including configuration information for the SRS channel estimation to the RU via the fronthaul interface. The configuration information may include a parameter indicating whether the SRS channel estimation by the RU is activated and a parameter indicating a reference level of SINR.

[0211] The RU as described above may include communication circuitry. The RU may include a memory storing instructions and including one or more storage media. For example, the RU may include at least one processor including processing circuitry. For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive from a DU via a fronthaul interface a control plane message including section information for SRS setup and section extension information indicating a range of PRBs for reporting SRS channel estimation. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive SRSs from a terminal on a plurality of PRBs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to identify at least one channel coefficient corresponding to a range of PRBs indicated by the section extension information based on channel estimation of the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to transmit a message to the DU via the fronthaul interface, the message including information about the at least one channel coefficient.

[0212] For example, the section extension information may include a parameter indicating a starting PRB within the plurality of PRBs, a parameter indicating the number of PRBs, and a parameter indicating a PRB interval between the PRBs.

[0213] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to transmit, to the DU, a first management plane message via the fronthaul interface, a first management plane message including capability information of the RU associated with the SRS channel estimation. The capability information may include a parameter indicating whether the RU supports the SRS channel estimation, a parameter indicating a repetition factor supported by the RU, a parameter indicating a maximum number of UEs supported by the RU, a parameter indicating a transmission comb size, a parameter indicating a number of cyclic shifts (CSs) supported by the RU, a parameter indicating a maximum number of symbols in a slot supported by the RU, a parameter indicating a maximum number of symbols in a frame supported by the RU, a parameter indicating a range of a reference level of a signal-to-interference plus noise ratio (SINR) supported by the RU, or a combination thereof.

[0214] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive a second management plane message from the DU via the fronthaul interface, the second management plane message including configuration information for the SRS channel estimation. The configuration information may include a parameter indicating whether the SRS channel estimation by the RU is enabled and a parameter indicating a reference level of the SINR.

[0215] For example, the section information may include a parameter indicating a repetition factor configured for the SRS and a parameter indicating a repetition index of a symbol of the SRS.

[0216] A DU as described above may include communication circuitry. The DU may include a memory storing instructions and including one or more storage media. The DU may include at least one processor including processing circuitry. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to transmit a control plane message to an RU via a fronthaul interface, the control plane message including section information for SRS setup and section extension information indicating a range of PRBs for reporting SRS channel estimation. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to receive from the RU via the fronthaul interface a message including information regarding at least one channel coefficient corresponding to the range of PRBs indicated by the section extension information. The at least one channel coefficient may be associated with the SRS channel estimation in the RU.

[0217] For example, the information indicating the range of the PRBs may include a parameter indicating a starting PRB within a plurality of PRBs for receiving SRSs, a parameter indicating the number of the PRBs, and a parameter indicating a PRB interval between the PRBs.

[0218] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the DU to receive, from the RU via the fronthaul interface, a first management plane message comprising capability information of the RU associated with the SRS channel estimation. The capability information may include a parameter indicating whether the RU supports the SRS channel estimation, a parameter indicating a repetition factor supported by the RU, a parameter indicating a maximum number of UEs supported by the RU, a parameter indicating a transmission comb size, a parameter indicating a number of cyclic shifts (CSs) supported by the RU, a parameter indicating a maximum number of symbols in a slot supported by the RU, a parameter indicating a maximum number of symbols in a frame supported by the RU, a parameter indicating a range of a reference level of a signal-to-interference plus noise ratio (SINR) supported by the RU, or a combination thereof.

[0219] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the DU to transmit a second management plane message to the RU via the fronthaul interface, the second management plane message including configuration information for the SRS channel estimation. The configuration information may include a parameter indicating whether the SRS channel estimation by the RU is enabled and a parameter indicating a reference level of the SINR.

[0220] For example, the section information may include a parameter indicating a repetition factor configured for the SRS and a parameter indicating a repetition index of a symbol of the SRS.

[0221] The method performed by the RU (radio unit) as described above may include receiving, from a distributed unit (DU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information associated with at least one physical resource block (PRB) for channel estimation using the SRSs. The method may include receiving the SRSs from a terminal on a plurality of PRBs. The method may include performing the channel estimation using the SRSs. The method may include identifying, based on the channel estimation using the SRSs, at least one channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs. The method may include transmitting, to the DU, a message including information about the at least one channel coefficient for the at least one PRB.

[0222] For example, the section extension information may include a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB.

[0223] For example, the method may include transmitting, to the DU, a first management plane message including capability information of the RU associated with the channel estimation. The capability information may include a parameter indicating whether the RU supports the channel estimation.

[0224] For example, the method may include receiving, from the DU, a second management plane message including configuration information for the channel estimation. The configuration information may include a parameter indicating whether the channel estimation by the RU is activated and a parameter indicating a reference level of a signal-to-interference plus noise ratio (SINR).

[0225] For example, the section information may include a parameter indicating a repetition factor that causes the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs.

[0226] A method performed by a distributed unit (DU) as described above may include transmitting, to a radio unit (RU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information associated with at least one physical resource block (PRB) for channel estimation using the SRSs. The method may include receiving, from the RU, a message including information about at least one channel coefficient for the at least one PRB indicated by the section extension information. The at least one channel coefficient may be associated with the channel estimation using the SRSs performed in the RU.

[0227] For example, the section extension information may include a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB.

[0228] For example, the method may include receiving, from the RU, a first management plane message including capability information of the RU associated with the channel estimation. The capability information may include a parameter indicating whether the RU supports the channel estimation.

[0229] For example, the method may include transmitting a second management plane message to the RU, the second management plane message including configuration information for the channel estimation. The configuration information may include a parameter indicating whether the channel estimation by the RU is activated and a parameter indicating a reference level of a signal-to-interference plus noise ratio (SINR).

[0230] For example, the section information may include a parameter indicating a repetition factor that causes the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs.

[0231] The RU as described above may include communication circuitry. The RU may include a memory storing instructions and including one or more storage media. The RU may include at least one processor including processing circuitry. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive, from a distributed unit (DU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information associated with at least one physical resource block (PRB) for channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive the SRSs from a terminal on a plurality of PRBs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to perform the channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to identify at least one channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs based on the channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the RU to transmit a message to the DU including information about the at least one channel coefficient for the at least one PRB.

[0232] For example, the section extension information may include a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB.

[0233] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to transmit a first management plane message to the DU, the first management plane message including capability information of the RU associated with the channel estimation. The capability information may include a parameter indicating whether the RU supports the channel estimation.

[0234] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the RU to receive a second management plane message from the DU that includes configuration information for the channel estimation. The configuration information may include a parameter indicating whether the channel estimation by the RU is enabled and a parameter indicating a reference level of the signal-to-interference plus noise ratio (SINR).

[0235] For example, the section information may include a parameter indicating a repetition factor that causes the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs.

[0236] The DU as described above may include communication circuitry. The DU may include a memory storing instructions and including one or more storage media. The DU may include at least one processor including processing circuitry. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to transmit, to a radio unit (RU), a control plane message including section information for identifying sounding reference signals (SRSs) and section extension information associated with at least one physical resource block (PRB) for channel estimation using the SRSs. The instructions, when individually or collectively executed by the at least one processor, may cause the DU to receive, from the RU, a message including information regarding at least one channel coefficient for the at least one PRB indicated by the section extension information. The at least one channel coefficient may be associated with the channel estimation using the SRSs performed in the RU.

[0237] For example, the section extension information may include a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB.

[0238] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the DU to receive a first management plane message from the RU, the first management plane message including capability information of the RU associated with the channel estimation. The capability information may include a parameter indicating whether the RU supports the channel estimation.

[0239] For example, the instructions, when individually or collectively executed by the at least one processor, may cause the DU to transmit a second management plane message to the RU that includes configuration information for the channel estimation. The configuration information may include a parameter indicating whether the channel estimation by the RU is enabled and a parameter indicating a reference level of the signal-to-interference plus noise ratio (SINR).

[0240] For example, the section information may include a parameter indicating a repetition factor that causes the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs.

[0241] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0242] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure. The one or more programs may be provided as a computer program product. The computer program product may be traded between a seller and a buyer as a commodity. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smart phones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created in a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0243] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0244] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0245] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0246] According to embodiments, one or more of the components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0247] Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible within the scope of the present disclosure.

Claims

1. In a method performed by RU (radio unit), An operation of receiving a control plane message from a distributed unit (DU) including section information for identifying sounding reference signals (SRSs) and section extension information related to at least one physical resource block (PRB) for channel estimation using the SRSs; An operation of receiving the SRSs from a terminal on multiple PRBs; An operation of performing channel estimation using the above SRSs; An operation of identifying at least one channel coefficient for at least one PRB indicated by the section extension information among the plurality of PRBs based on the channel estimation using the SRSs; and An operation of transmitting a message including information about at least one channel coefficient for at least one PRB to the DU, method.

2. In paragraph 1, The above section extension information includes a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB. method.

3. In paragraph 1, Further comprising an operation of transmitting a first management plane message including capability information of the RU associated with the channel estimation to the DU, The above capability information includes a parameter indicating whether the RU supports the channel estimation. method.

4. In paragraph 1, Further comprising the operation of receiving a second management plane message including configuration information for the channel estimation from the DU, The above configuration information includes a parameter indicating whether the channel estimation by the RU is activated and a parameter indicating a reference level of signal-to-interference plus noise ratio (SINR). method.

5. In paragraph 1, The section information includes a parameter indicating a repetition factor causing the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs. method. In 6.RU(radio unit), communication circuit; A memory storing instructions and including one or more storage media; and At least one processor comprising a processing circuit, The above instructions, when individually or collectively executed by the at least one processor, Receive a control plane message from a distributed unit (DU) including section information for identifying SRSs (sounding reference signals) and section extension information related to at least one PRB (physical resource block) for channel estimation using the SRSs, Receive the SRSs from the terminal on multiple PRBs, The channel estimation is performed using the above SRSs, Based on the channel estimation using the SRSs, identifying at least one channel coefficient for the at least one PRB indicated by the section extension information among the plurality of PRBs, and To transmit to the DU a message including information about the at least one channel coefficient for the at least one PRB; causing the above RU, RU.

7. In paragraph 6, The above section extension information includes a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB. RU.

8. In paragraph 6, The above instructions, when individually or collectively executed by the at least one processor, To transmit a first management plane message including capability information of the RU associated with the channel estimation to the DU, Causes the above RU, The above capability information includes a parameter indicating whether the RU supports the channel estimation. RU.

9. In paragraph 6, The above instructions, when individually or collectively executed by the at least one processor, To receive a second management plane message including configuration information for the channel estimation from the DU, Causes the above RU, The above configuration information includes a parameter indicating whether the channel estimation by the RU is activated and a parameter indicating a reference level of the SINR (signal-to-interference plus noise ratio). RU.

10. In paragraph 6, The section information includes a parameter indicating a repetition factor causing the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs. RU. In 11.DU (distributed unit), communication circuit; A memory storing instructions and including one or more storage media; and At least one processor comprising a processing circuit, The above instructions, when individually or collectively executed by the at least one processor, Transmitting a control plane message to a radio unit (RU) including section information for identifying SRSs (sounding reference signals) and section extension information related to at least one PRB (physical resource block) for channel estimation using the SRSs, To receive from the RU a message including information about at least one channel coefficient for the at least one PRB indicated by the section extension information, Causes the above DU, wherein said at least one channel coefficient is associated with said channel estimation using said SRSs performed in said RU, DU.

12. In paragraph 11, The above section extension information includes a parameter indicating a start PRB of the at least one PRB, a parameter indicating the number of the at least one PRB, and a parameter indicating an interval between a PRB included in the at least one PRB and another PRB included in the at least one PRB and adjacent to the PRB. DU.

13. In paragraph 11, The above instructions, when individually or collectively executed by the at least one processor, To receive a first management plane message from the RU, the first management plane message including capability information of the RU associated with the channel estimation; Causes the above DU, The above capability information includes a parameter indicating whether the RU supports the channel estimation. DU.

14. In paragraph 11, The above instructions, when individually or collectively executed by the at least one processor, To transmit a second management plane message including configuration information for the channel estimation to the RU, Causes the above DU, The above configuration information includes a parameter indicating whether the channel estimation by the RU is activated and a parameter indicating a reference level of the SINR (signal-to-interference plus noise ratio). DU.

15. In paragraph 11, The section information includes a parameter indicating a repetition factor causing the terminal to repeatedly transmit the SRSs and a parameter indicating a repetition index of a symbol of each of the SRSs. DU.

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