KR20240014009A - Electornic device and method for providing sounding referecne signal configuration in fronthaul interface - Google Patents

Abstract

In embodiments, a method performed by a radio unit (RU) may include receiving sounding reference signals (SRS). The method may include receiving a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface. The method may include performing channel estimation based on the SRSs and the SRS configuration information. The method may include performing beamforming based on the channel estimation.

Description

Electronic device and method for providing SRS settings in a fronthaul interface {ELECTORNIC DEVICE AND METHOD FOR PROVIDING SOUNDING REFERECNE SIGNAL CONFIGURATION IN FRONTHAUL INTERFACE}

This disclosure relates to a fronthaul interface. More specifically, the present disclosure relates to an electronic device and method for providing sounding reference signal (SRS) configuration in a fronthaul interface.

As transmission capacity increases in wireless communication systems, function split, which functionally separates base stations, is being applied. Depending on the separation of functions, the base station can be divided into a distributed unit (DU) and a radio unit (RU). A fronthaul interface is defined for communication between DUs and RUs.

In embodiments, a method performed by a radio unit (RU) may include receiving sounding reference signals (SRS). The method may include receiving a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface. The method may include performing channel estimation based on the SRSs and the SRS configuration information. The method may include performing beamforming based on the channel estimation.

In embodiments, a method performed by a distributed unit (DU) includes generating SRS configuration information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU). can do. The method may include transmitting a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface. The channel estimation may be used for beamforming in the RU.

In embodiments, an electronic device of a radio unit (RU) includes at least one fronthaul transceiver, at least one RF transceiver, and at least one coupled to the at least one fronthaul transceiver and the at least one RF transceiver. May include a processor. The at least one processor may be configured to receive sounding reference signals (SRS). The at least one processor may be configured to receive a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface. The at least one processor may be configured to perform channel estimation based on the SRSs and the SRS configuration information. The at least one processor may be configured to perform beamforming based on the channel estimation.

In embodiments, an electronic device of a distributed unit (DU) includes at least one transceiver. And it may include at least one processor coupled to the at least one transceiver. The at least one processor may be configured to generate SRS setting information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU). The at least one processor may be configured to transmit a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface. The channel estimation may be used for beamforming in the RU.

1 shows a wireless communication system according to embodiments.
2A shows a fronthaul interface according to embodiments.
FIG. 2B illustrates a fronthaul interface of an open (O)-radio access network (RAN) according to embodiments.
FIG. 3A shows the functional configuration of a distributed unit (DU) according to embodiments.
FIG. 3B shows the functional configuration of a radio unit (RU) according to embodiments.
Figure 4 shows an example of function split between DU and RU, according to embodiments.
Figure 5 shows an example of a sounding reference signal (SRS) channel estimation of a RU, according to embodiments.
Figure 6 shows an example of the functional configuration of a RU for SRS channel estimation, according to embodiments.
Figure 7 shows an example of signaling between DU and RU for SRS channel estimation of RU, according to embodiments.
Figure 8 shows an example of a control plane (C-plane) message including SRS configuration information according to an embodiment.
Figure 9 shows an example of SRS multiplexing information for each UE according to an embodiment.
Figure 10 shows an example of SRS channel information according to one embodiment.
11A and 11B show examples of SRS channel estimation according to a management plane (M-plane) message, according to one embodiment.
Figure 12 shows examples of SRS channel estimation according to RU capability according to one embodiment.

Terms used in the present disclosure are merely used to describe specific embodiments and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions, unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by a person of ordinary skill in the technical field described in this disclosure. Among the terms used in this disclosure, terms defined in general dictionaries may be interpreted to have the same or similar meaning as the meaning they have in the context of related technology, and unless clearly defined in this disclosure, have an ideal or excessively formal meaning. It is not interpreted as In some cases, even terms defined in the present disclosure cannot be interpreted to exclude embodiments of the present disclosure.

In various embodiments of the present disclosure described below, a hardware approach method is explained as an example. However, since various embodiments of the present disclosure include technology using both hardware and software, the various embodiments of the present disclosure do not exclude software-based approaches.

Terms used in the following description refer to configuration (e.g., setup, setting, arrangement, control), and terms that refer 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, resource block (RB), bandwidth part (BWP), opportunity), terms for operational states (e.g. step, operation, procedure), data. Terms (e.g. packet, message, user stream, information, bit, symbol, codeword), terms referring to channels, terms referring to network entities ( DU (distributed unit), RU (radio unit), CU (central unit), CU-CP (control plane), CU-UP (user plane), O-DU (O-RAN (open radio access network) DU), O-RAN RU (O-RU), O-RAN CU (O-CU), O-RAN CU-CP (O-CU-UP), O-RAN CU-CP (O-CU-CP), device Terms referring to the components are exemplified for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meaning may be used. In addition, terms such as '... part', '... base', '... water', and '... body' used hereinafter mean at least one shape structure or a unit that processes a function. It can mean.

In addition, in the present disclosure, the expressions greater than or less than may be used to determine whether a specific condition is satisfied or fulfilled, but this is only a description for expressing an example, and the description of more or less may be used. It's not exclusion. Conditions written as ‘more than’ can be replaced with ‘more than’, conditions written as ‘less than’ can be replaced with ‘less than’, and conditions written as ‘more than and less than’ can be replaced with ‘greater than and less than’. In addition, hereinafter, 'A' to 'B' means at least one of the elements from A to (including A) and B (including B).

The present disclosure describes various embodiments using terms used in some communication standards (e.g., 3rd Generation Partnership Project (3GPP), extensible radio access network (xRAN), and open-radio access network (O-RAN)), This is only an example for explanation, and various embodiments of the present disclosure can be easily modified and applied to other communication systems.

1 shows a wireless communication system according to embodiments.

Referring to FIG. 1, FIG. 1 illustrates a base station 110 and a terminal 120 as some of the nodes that use a wireless channel in a wireless communication system. Although FIG. 1 shows only one base station, the wireless communication system may further include other base stations that are the same or similar to base station 110.

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 signals can be transmitted. In addition to the base station, the base station 110 includes 'access point (AP)', 'eNodeB (eNB)', '5G node (5th generation node)', and 'next generation nodeB'. , gNB)', 'wireless point', 'transmission/reception point (TRP)', or other terms with equivalent technical meaning.

The terminal 120 is a device used by a user and communicates with the base station 110 through a wireless channel. The link from the base station 110 to the terminal 120 is called downlink (DL), and the link from the terminal 120 to the base station 110 is called uplink (UL). Additionally, although not shown in FIG. 1, the terminal 120 and another terminal may communicate with each other through a wireless channel. At this time, the link between the terminal 120 and other terminals (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, terminal 120 may operate without user involvement. According to one embodiment, the terminal 120 is a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, according to one embodiment, the terminal 120 may be a narrowband (NB)-internet of things (IoT) device.

The terminal 120 includes 'user equipment (UE)', 'customer premises equipment (CPE)', 'mobile station', and 'subscriber station' in addition to the terminal. , may be referred to as a ‘remote terminal’, a ‘wireless terminal’, an electronic device’, or a ‘user device’ or other terms with equivalent technical meaning. .

The base station 110 may perform beamforming with the terminal 120. The base station 110 and the terminal 120 may 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 use relatively high frequency bands (e.g., FR 2 (or, FR 2-1, FR 2-2, FR 2-3), FR 3 in NR), millimeter waves ( It is possible to transmit and receive wireless signals in mmWave bands (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz). To improve channel gain, the base station 110 and the terminal 120 may perform beamforming. Here, beamforming may include transmission beamforming and reception beamforming. The base station 110 and the terminal 120 can provide directionality to a transmitted signal or a 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 serving beams are selected, subsequent communication can be performed through a resource in a QCL relationship with the resource that transmitted the serving beams.

A first antenna port and a second antenna port are said to be in a QCL relationship if the large-scale characteristics of the channel carrying the symbols on the first antenna port can be inferred from the channel carrying the symbols on the second antenna port. can be evaluated. For example, a wide range of characteristics include delay spread, doppler spread, doppler shift, average gain, average delay, and spatial receiver parameters. It may include at least one of:

In FIG. 1, both the base station 110 and the terminal 120 are depicted as performing beamforming, but embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Additionally, the base station may or may not perform beamforming. That is, only one of the base station and the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

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

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

2A shows a fronthaul interface according to embodiments. Fronthaul refers to the link between entities of the base station after the radio access network, unlike the backhaul between the base station and the core network. FIG. 2A shows an example of a fronthaul structure between a DU 210 and one RU 220, but this is only for convenience of explanation and the present disclosure is not limited thereto. In other words, the embodiment of the present disclosure can also be applied to the fronthaul structure between one DU and multiple RUs. For example, embodiments of the present disclosure can be applied to a fronthaul structure between one DU and two RUs. Additionally, embodiments of the present disclosure can also be applied to a fronthaul structure between one DU and three RUs.

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

As communication technology develops, mobile data traffic increases, and accordingly, the bandwidth requirement for the fronthaul between digital units and wireless units has increased significantly. In a deployment such as a centralized/cloud radio access network (C-RAN), the DU 210 provides functions for packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical (PHY). The RU 220 may be implemented to perform further functions for the PHY layer in addition to the radio frequency (RF) function.

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

The RU 220 may be responsible for lower layer functions of the wireless network. For example, the RU 220 may perform part of the PHY layer and RF functions. Here, the part of the PHY layer is one that is performed at a relatively lower level than the DU 210 among the functions of the PHY layer, for example, iFFT conversion (or FFT conversion), CP insertion (CP removal), and digital beamforming. It can be included. An example of this specific functional separation is detailed in Figure 4. RU 220 is an 'access unit (AU)', 'access point (AP)', 'transmission/reception point (TRP)', 'remote radio head (RRH) )', 'radio unit (RU)', or other terms with equivalent technical meaning. According to one embodiment, if the RU 220 complies with the O-RAN standard, it may be referred to as an O-RAN RU (O-RU). The RU 220 may be replaced with a second network entity for a base station (eg, gNB) in embodiments of the present disclosure, if necessary.

Although FIG. 2A illustrates that the base station 110 includes a DU 210 and a RU 220, embodiments of the present disclosure are not limited thereto. The base station according to embodiments includes a centralized unit (CU) configured to perform the functions of the upper layers of the access network (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)) and a lower layer. It can be implemented as a distributed deployment according to distributed units (DUs) configured to perform functions. At this time, the distributed unit (DU) may include the digital unit (DU) and radio unit (RU) of FIG. 1. Between the core (e.g. 5GC (5G core) or NGC (next generation core)) network and the radio network (RAN), base stations may be implemented in a structure in which they are arranged in the order of CU, DU, and RU. The interface between the CU and distributed unit (DU) may be referred to as the F1 interface.

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

FIG. 2B illustrates a fronthaul interface of an open (O)-radio access network (RAN) according to embodiments. As a base station 110 according to distributed deployment, an eNB or gNB is exemplified.

Referring to FIG. 2B, the base station 110 may include an O-DU 251 and O-RUs 253-1, ..., 253-n. Hereinafter, for convenience of explanation, the operations and functions of the O-RU 253-1 may be understood as explanations for each of other O-RUs (eg, O-RU 253-n).

The O-DU 251 includes functions excluding functions exclusively assigned to the O-RU 253-1 among the functions of the base station (e.g., eNB, gNB) according to FIG. 4, which will be described later. It is a logical node that does. O-DU (251) can control the operation of O-RUs (253-1, ..., 253-n). The O-DU 251 may be referred to as a lower layer split (LLS) central unit (CU). The O-RU 253-1 is a logical node that includes a subset of the functions of a base station (e.g., eNB, gNB) according to FIG. 4, which will be described later. Real-time aspects of control plane (C-plane) communication and user plane (U-plane) communication with the O-RU 253-1 may be controlled by the O-DU 251.

The O-DU 251 can communicate with the O-RU 253-1 through an LLS interface. The LLS interface corresponds to the fronthaul interface. The LLS interface refers to a logical interface between the O-DU 251 and the O-RU 253-1 using lower layer functional split (i.e., intra-PHY-based functional split). LLS-C between O-DU (251) and O-RU (253-1) provides C-plane through the LLS interface. LLS-U between O-DU (251) and O-RU (253-1) provides U-plane through the LLS interface.

In FIG. 2B, to explain O-RAN, the entities of the base station 110 are referred to as O-DU and O-RU. However, these names should not be construed as limiting the embodiments of the present disclosure. In the embodiments described through FIGS. 3A to 9, of course, the operations of the DU 210 can be performed by the O-DU 251. The description of DU 210 may be applied to O-DU 251. Likewise, in the embodiments described through FIGS. 3A to 9, of course, the operations of the RU 220 may be performed by the O-RU 253-1. The description of RU 220 may be applied to O-DU 253-1.

FIG. 3A shows the functional configuration of a distributed unit (DU) according to embodiments. The configuration illustrated in FIG. 3A may be understood as the configuration of DU 210 in FIG. 2A (or O-DU 250 in FIG. 2B) as part of a base station. Terms such as '... unit' and '... unit' used hereinafter refer to a unit that processes at least one function or operation, which can be implemented through hardware, software, or a combination of hardware and software. there is.

Referring to FIG. 3A, the DU 210 includes a transceiver 310, a memory 320, and a processor 330.

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

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 standard of the system. For example, when transmitting data, the transceiver 310 generates complex symbols by encoding and modulating the transmission bit stream. Additionally, when receiving data, the transceiver 310 restores the received bit stream by demodulating and decoding the baseband signal. Additionally, the transceiver 310 may include multiple transmission and reception paths. Additionally, according to one embodiment, the transceiver 310 may be connected to the core network or to other nodes (eg, integrated access backhaul (IAB)).

The transceiver 310 can transmit and receive signals. For example, the transceiver 310 may transmit a management plane (M-plane) message. For example, the transceiver 310 may transmit a synchronization plane (S-plane) message. For example, the transceiver 310 may transmit a control plane (C-plane) message. For example, the transceiver 310 may transmit a user plane (U-plane) message. For example, transceiver 310 may receive a user plane message. Although only the transceiver 310 is shown in FIG. 3A, according to another implementation example, the DU 210 may include two or more transceivers.

The transceiver 310 transmits and receives signals as described above. Accordingly, all or part of the transceiver 310 may be referred to as a 'communication unit', a 'transmission unit', a 'reception unit', or a 'transmission/reception unit'. Additionally, in the following description, transmission and reception performed through a wireless channel are used to mean that processing as described above is performed by the transceiver 310.

Although not shown in FIG. 3A, the transceiver 310 may further include a backhaul transceiver for connection to the core network or another base station. The backhaul transceiver provides an interface to communicate with other nodes in the network. In other words, the backhaul transceiver converts the bit string transmitted from the base station to other nodes (e.g., other access nodes, other base stations, upper nodes, core networks, etc.) into physical signals, and the physical signals received from other nodes into bit strings. Convert.

The memory 320 stores data such as basic programs, application programs, and setting information for operation of the DU 210. Memory 320 may be referred to as a storage unit. The memory 320 may be comprised of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. And, the memory 320 provides stored data according to the request of the processor 330.

The processor 330 controls the overall operations of the DU (210). The processor 380 may be referred to as a control unit. For example, the processor 330 transmits and receives signals through the transceiver 310 (or through the backhaul communication unit). Additionally, the processor 330 writes and reads data into the memory 320. Additionally, the processor 330 can perform protocol stack functions required by communication standards. Although only the processor 330 is shown in FIG. 3A, according to another implementation example, the DU 210 may include two or more processors.

The configuration of the DU 210 shown in FIG. 3A is only an example, and the example of the DU performing the embodiments of the present disclosure is not limited to the configuration shown in FIG. 3A. In some embodiments, some configurations may be added, deleted, or changed.

FIG. 3B shows the functional configuration of a radio unit (RU) according to embodiments. The configuration illustrated in FIG. 3B may be understood as a configuration of the RU 220 of FIG. 2B or the O-RU 253-1 of FIG. 2B as part of a base station. Terms such as '... unit' and '... unit' used hereinafter refer to a unit that processes at least one function or operation, which may be implemented through hardware or software, or a combination of hardware and software. there is.

Referring to FIG. 3B, the RU 220 includes an RF transceiver 360, a fronthaul transceiver 365, a memory 370, and a processor 380.

The RF transceiver 360 performs functions for transmitting and receiving signals through a wireless channel. For example, the RF transceiver 360 upconverts the baseband signal into an RF band signal and transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal. For example, the RF transceiver 360 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

The RF transceiver 360 may include multiple transmission and reception paths. Furthermore, the RF transceiver 360 may include an antenna unit. The RF transceiver 360 may include at least one antenna array comprised of multiple antenna elements. In terms of hardware, the RF transceiver 360 may be composed of digital circuits and analog circuits (eg, radio frequency integrated circuit (RFIC)). Here, the digital circuit and analog circuit can be implemented in one package. Additionally, the RF transceiver 360 may include multiple RF chains. The RF transceiver 360 may perform beamforming. The RF transceiver 360 may apply a beamforming weight to the signal to be transmitted and received in order to give directionality according to the settings of the processor 380. According to one embodiment, the RF transceiver 360 may include a radio frequency (RF) block (or RF unit).

According to one embodiment, the RF transceiver 360 may transmit and receive signals on a radio access network. For example, the RF transceiver 360 may transmit a downlink signal. Downlink signals include synchronization signal (SS), reference signal (RS) (e.g., cell-specific reference signal (CRS), demodulation (DM)-RS), system information (e.g., MIB, SIB, It may include remaining system information (RMSI), other system information (OSI), configuration message, control information, or downlink data. Additionally, for example, the RF transceiver 360 may receive an uplink signal. Uplink signals include random access-related signals (e.g., random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), reference signals (e.g., sounding reference signal (SRS), DM) -RS), or power headroom report (PHR), etc. Although only the RF transceiver 360 is shown in FIG. 3B, according to another implementation example, the RU 220 may include two or more RF transceivers.

The fronthaul transceiver 365 can transmit and receive signals. According to one embodiment, the fronthaul transceiver 365 may transmit and receive signals on the fronthaul interface. For example, the fronthaul transceiver 365 may receive a management plane (M-plane) message. For example, the fronthaul transceiver 365 may receive a synchronization plane (S-plane) message. For example, the fronthaul transceiver 365 may receive a control plane (C-plane) message. For example, the fronthaul transceiver 365 may transmit a user plane (U-plane) message. For example, fronthaul transceiver 365 may receive user plane messages. Although only the fronthaul transceiver 365 is shown in FIG. 3B, according to another implementation example, the RU 220 may include two or more fronthaul transceivers.

The RF transceiver 360 and the fronthaul transceiver 365 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 'transmission unit', a 'reception unit', or a 'transceiver unit'. Additionally, in the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the RF transceiver 360. In the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the RF transceiver 360.

The memory 370 stores data such as basic programs, application programs, and setting information for operation of the RU 220. Memory 370 may be referred to as a storage unit. The memory 370 may be comprised of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. And, the memory 370 provides stored data according to the request of the processor 380. According to one embodiment, memory 370 may include memory for conditions, commands, or setting values related to the SRS transmission method.

The processor 380 controls the overall operations of the RU (220). The processor 380 may be referred to as a control unit. For example, processor 380 transmits and receives signals through RF transceiver 360 or fronthaul transceiver 365. Additionally, the processor 380 writes and reads data into the memory 370. Additionally, the processor 380 can perform protocol stack functions required by communication standards. Although only the processor 380 is shown in FIG. 3B, according to another implementation example, the RU 220 may include two or more processors. The processor 380 is a set of instructions or code stored in the memory 370, which is a storage space that stores instructions/code or instructions/code that are at least temporarily residing in the processor 380, or the processor 380 It may be part of the circuitry that constitutes. Additionally, the processor 380 may include various modules for performing communication. The processor 380 may control the RU 220 to perform operations according to embodiments described later.

The configuration of the RU 220 shown in FIG. 3B is only an example, and the example of the RU that performs the embodiments of the present disclosure is not limited to the configuration shown in FIG. 3B. In some embodiments, some configurations may be added, deleted, or changed.

Figure 4 shows an example of function split between DU and RU, according to embodiments. As wireless communication technology develops (e.g., the introduction of ^{the 5th} generation (5G) communication system (or the introduction of the new radio (NR) communication system), the frequency bands used have further increased. As the cell radius of the base station becomes very small, The number of RUs required to be installed has further increased. Additionally, in the 5G communication system, the amount of data transmitted has increased by more than 10 times, and the transmission capacity of the wired network transmitted through the fronthaul has increased significantly. Factors mentioned above In the 5G communication system, the installation cost of the wired network can increase significantly. Therefore, in order to lower the transmission capacity of the wired network and reduce the installation cost of the wired network, some functions of the DU's modem are installed. 'Function split', which lowers the fronthaul transmission capacity by transferring it to the RU, can be used.

To reduce the burden on the DU, the role of the RU, which is responsible only for existing RF functions, can be expanded to include some functions of the physical layer. As the RU performs higher layer functions, the throughput of the RU increases, thereby increasing the transmission bandwidth in the fronthaul, and at the same time, the latency requirement constraints due to response processing can be lowered. Meanwhile, as the RU performs higher layer functions, the virtualization gain decreases, and the size, weight, and cost of the RU increase. Considering the trade-off of the advantages and disadvantages described above, it is necessary to implement optimal functional separation.

Referring to Figure 4, functional separations in the physical layer below the MAC layer are shown. In the case of downlink (DL), which transmits signals to the terminal through a wireless network, the base station sequentially performs channel encoding/scrambling, modulation, layer mapping, antenna mapping, RE mapping, digital beamforming (e.g. precoding), iFFT conversion/CP insertion, and RF conversion can be performed. In the case of uplink (UL), which receives signals from a terminal through a wireless network, the base station sequentially performs RF conversion, FFT conversion/CP removal, digital beamforming (pre-combining), and RE decoding. Mapping, channel estimation, layer demapping, demodulation, and decoding/descrambling can be performed. Separation of uplink functions and downlink functions can be defined in various types depending on the need between vendors (vendors), discussions on specifications, etc. according to the trade-off described above.

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

According to one embodiment, when large-capacity signal processing is expected, such as FR 1 MMU, function separation at a relatively high layer (e.g., fourth function separation 420b) may be required to reduce fronthaul capacity. . In addition, separation of functions at too high a layer (e.g., the sixth function separation 430) may cause a burden on the implementation of the RU due to the complicated control interface and the inclusion of multiple PHY processing blocks within the RU. Appropriate separation of functions may be required depending on the arrangement and implementation method of the and RU.

According to one embodiment, when precoding of data received from the DU cannot be processed (i.e., when there is a limit to the precoding capability of the RU), the third function separation 420a or a lower function is performed. Separation (e.g., second functional separation 410) may be applied. Conversely, if there is a capability to process precoding of data received from the DU, the fourth functional separation 420b or a higher functional separation (e.g., the sixth functional separation 430) may be applied. In the O-RAN standard, the type of O-RU is distinguished depending on whether the precoding function is located on the interface of the O-DU or the O-RU interface. An O-RU in which precoding is not performed (i.e., low complexity) may be referred to as a CAT-A O-RU. The O-RU where precoding is performed may be referred to as a CAT-B O-RU.

Embodiments of the present disclosure illustrate the specifications of eCPRI and O-RAN as fronthaul interfaces when transmitting messages between a DU (e.g., DU 210 in FIG. 2A) and RU (e.g., RU 220 in FIG. 2A). It is described negatively. The Ethernet payload of the message may include an eCPRI header, an O-RAN header, and additional fields. Hereinafter, various embodiments of the present disclosure will be described using the standard terms of eCPRI or O-RAN, but other expressions having equivalent meaning to each term may be used instead of the various embodiments of the present disclosure.

Fronthaul's transport protocol can be Ethernet and eCPRI, which are easy to share with networks. The eCPRI header and O-RAN header may be included in the Ethernet payload. The eCPRI header can be located in front of the Ethernet payload. The contents of the eCPRI header are as follows.

1) ecpriVersion (4 bits): This parameter indicates the eCPRI protocol version.

2) ecpriReserved (3 bits): This parameter is reserved for future use of eCPRI.

3) ecpriConcatenation (1 bit): This parameter indicates when eCPRI concatenation is in use.

4) ecpriMessage (1 byte): This parameter indicates the type of service carried by the message type. For example, the parameter represents an IQ data message, a real-time control data message, or a transport network delay measurement message.

5) ecpriPayload (2 bytes): This parameter indicates the byte size of the payload portion of the eCPRI message.

6) ecpriRtcid/ecpriPcid (2 bytes): This parameter is the extended antenna-carrier (eAxC) identifier (eAxC ID) and identifies the specific data flow associated with each C-Plane (ecpriRtcid) or U-Plane (ecpriPcid) message. do.

7) ecpriSeqid (2 bytes): This parameter provides unique message identification and ordering at two levels. The first octet of this parameter is the sequence ID, which is used to identify the order of messages within the eAxC message stream, and the sequence ID is used to ensure that all messages have been received and to reorder out-of-order messages. The second octet of this parameter is the subsequence ID. The subsequence ID is used to determine order and implement reordering when radio-transport-level (eCPRI or IEEE-1914.3) fragmentation occurs.

The eAxC identifier (ID) is a band and sector identifier ('BandSector_ID'), a component carrier identifier ('CC_ID'), a spatial stream identifier ('RU_Port_ID'), and a distributed unit identifier ('DU_Port_ID'). Includes. Bit allocation of eAxC ID can be divided as follows.

1) DU_port ID: To distinguish processing units in O-DU, DU_port ID is used (e.g. different baseband cards). It is expected that the O-DU allocates bits for the DU_port ID and the O-RU attaches the same value to the UL U-Plane message carrying the same sectionId data.

2) BandSector_ID: Aggregated cell identifier (band and sector distinction supported by O-RU).

3) CC_ID: CC_ID distinguishes carrier components supported by O-RU.

4) RU_port ID: RU_port ID specifies logical flows such as data layer or spatial stream, and signal channels that require separate numerologies (e.g. PRACH) or special antenna allocation such as SRS. do.

The fronthaul application protocol is the control plane (C-plane), user plane (U-plane), synchronization plane (S-plane), and management plane (M). -plane) may be included.

The control plane may be configured to provide scheduling information and beamforming information through control messages. The control plane means real-time control between DU and RU. The user plane may contain IQ sample data transmitted between DU and RU. The user plane may include the user's downlink data (IQ data or SSB/RS), uplink data (IQ data or SRS/RS), or PRACH data. The weight vector of the above-described beamforming information may be multiplied by the user's data. Synchronization plane generally refers to the traffic between DU and RU to a synchronization controller (e.g. IEEE Grand Master). The synchronization plane may be related to timing and synchronization. The management plane refers to non-real-time control between DU and RU. The management plane may be related to initial setup, non-realtime reset or reset, and non-realtime report.

Messages in the control plane, i.e. C-plane messages, can be encapsulated based on a two-layer header approach. The first layer may consist of the eCPRI common header or IEEE 1914.3 common header, which contains fields used to indicate the message type. The second layer is the application layer, which contains fields required for control and synchronization. Within the application layer, a section defines the characteristics of U-plane data transmitted or received on a beam with one pattern ID. The section types supported within C-plane are as follows.

Section Type may indicate the purpose of the control message transmitted in the control plane. For example, the purpose of each Section Type is as follows.

1) sectionType=0: Used to indicate unused resource blocks or symbols in DL or UL.

2) sectionType=1: Used for most DL/UL wireless channels. Here, “most” refers to channels that do not require time or frequency offset, such as is required for mixed numerology channels.

3) sectionType=2: reserved for further use

4) sectionType=3: PRACH and mixed-numerology channel. Channels that require time or frequency offset or differ from the nominal SCS value(s)

5) sectionType=4: reserved for further use

6) sectionType=5: UE scheduling information. Delivers UE scheduling information so that RU can calculate BF weight in real time (O-RAN optional BF method)

7) sectionType=6: UE-specific channel information transmission. Periodically transmit UE channel information so that RU can calculate BF weight in real time (O-RAN optional BF method)

8) sectionType=7: Used for LAA support

For channel estimation in the uplink, the terminal may transmit a sounding reference signal (SRS) to the base station. The base station may perform channel estimation based on the received SRS. The base station can perform communication based on the channel estimation result. For example, the base station may perform beamforming (eg, digital beamforming or analog beamforming) based on the channel estimation result.

Depending on the type of function split of the base station (e.g., function splits in FIG. 4), channel estimation may be performed in DU or RU. For example, in the third function separation 420a (Option 7-2x Category A) or the fourth function separation 420b (Option 7-2x Category B), RE de-mapping to SRS or RE to SRS Channel estimation may be performed in the DU. The DU may transmit channel information obtained based on the channel estimation result to the RU. Afterwards, the RU can perform beamforming based on channel information. However, because channel estimation is performed in the DU, a processing delay occurs between the time the RU receives the SRS and the time it acquires channel information. In particular, if the fronthaul capacity between DU and RU is insufficient, the delay in the fronthaul interface is large. Because the channel changes over time, the longer the delay time between receiving the SRS and applying the channel estimation result to beamforming, the lower the beamforming performance.

To solve the above-described problem, in embodiments of the present disclosure, channel estimation using SRS (hereinafter referred to as SRS channel estimation) may be performed in the RU. Through the RU's SRS channel estimation, the burden on the fronthaul interface between the DU and RU can be reduced. Additionally, as the processing delay required to acquire channel information is reduced, the RU can acquire channel information that substantially matches the current wireless channel. Accordingly, beamforming performance according to SRS channel estimation can be improved. Hereinafter, in this disclosure, operations of the RU for SRS channel estimation and signaling required to perform SRS channel estimation in the RU are described.

Figure 5 shows an example of a sounding reference signal (SRS) channel estimation of a RU, according to embodiments. RU illustrates RU 220 in FIG. 2A. According to one embodiment, RU 220 may include O-RU 253-1.

(1) Access network

Referring to FIG. 5, the operations of the terminal 120 and the RU 220 in an access network are described. The UE (e.g., UE 120 in FIG. 1) may transmit SRSs 510 to the RU 220. Terminal 120 may generate SRS sequences. The terminal 120 may generate SRS sequences based on higher layer signaling (e.g., radio resource control signaling (RRC)) received from a base station (e.g., DU 210, RU 220).

Higher layer signaling for SRS transmission may include parameters for each SRS resource. For example, parameters for SRS transmission may include resource mapping information. The resource mapping information may include the position of the SRS symbol to which SRS sequences are mapped (eg, position from the last symbol of the slot), the number of SRS symbols, and a repetition factor. Additionally, for example, parameters for SRS transmission may include transmission comb information. The transmission comb information may include a comb value, a comb offset, and a cyclic shift value. Additionally, for example, parameters for SRS transmission may include resource type information. The resource type information may indicate whether SRS transmission is periodic, semi-persistent, or aperiodic. When SRS transmission is periodic or semi-permanent, the resource type information may include information indicating the period and offset. Additionally, for example, parameters for SRS transmission may include frequency hopping information. Frequency hopping information may include parameters for SRS frequency hopping (e.g., C _SRS , B _SRS , b _hop in 3GPP TS 38.211). Additionally, for example, parameters for SRS transmission may include hopping method information. The hopping method information may indicate group hopping, sequence hopping, or 'neither'. Additionally, for example, parameters for SRS transmission may include frequency domain information. Frequency domain information may include a frequency domain shift value and frequency position parameter in the frequency domain when allocating an SRS. Additionally, for example, parameters for SRS transmission may include partial frequency sounding information. Partial frequency sounding information may include a starting RB index, a frequency scaling factor, and an indicator for RB hopping activity.

The RU 220 may transmit the downlink signal 520 to the terminal 120. For example, the RU 220 may transmit the downlink signal 520 to the terminal 120 based on the received SRSs 510. According to one embodiment, the downlink signal 520 may include downlink control information. The RU 220 may generate control information based on the channel estimation result. RU 220 may transmit control information to UE 120. Based on the control information, the RU 220 may receive an uplink signal from the terminal 120 or transmit data to the terminal 120. For example, the control information may include downlink resource allocation. Additionally, for example, the control information may include uplink resource allocation. Additionally, for example, the control information may include beamforming information (e.g., 3GPP transmission configuration indication (TCI) state). Additionally, for example, the control information may include precoding information. As an example, the precoding information may include a precoding matrix indicator (PMI). Additionally, for example, the control information may include SRS index information.

According to one embodiment, the downlink signal 520 may include downlink data (eg, physical downlink shared channel (PDSCH)). The RU 220 may estimate the downlink channel based on channel reciprocity. At this time, the duplex mode of the frequency band of the downlink signal 520 may be time duplex division (TDD). The RU 220 may transmit downlink data based on the downlink channel estimation result.

In FIG. 5, only the transmission of the downlink signal 520 is shown, but embodiments of the present disclosure are not limited thereto. For example, the RU 220 generates an uplink signal (e.g., uplink control information (UCI), SRS, physical uplink shared channel (PUSCH), and physical random access channel (PRACH) based on the result of the SRS channel estimation 530. )) can be received. Meanwhile, in another example, the RU 220 may transmit the generated downlink signal 520 to the terminal 120 regardless of the received SRSs 510.

(2) RU: SRS channel estimation (530) and beamforming (540)

Within the RU 220, SRS channel estimation 530 and the operations of the RU 220 according to the results of the channel estimation are described. RU 220 may perform SRS channel estimation 530. As SRS channel estimation 530 is performed in the RU 220, a new LLS structure between the DU 210 and the RU 220 may be defined. SRS channel estimation 530 refers to the operation of the RU 220 to obtain information about the uplink channel with the terminal 120 based on SRSs transmitted from the terminal 120. RU 220 may perform beamforming 540. For example, the RU 220 may perform beamforming 540 based on the result of SRS channel estimation 530.

Beamforming 540 may be executed in at least one of the frequency domain or the time domain. Beamforming 540 may be performed in the frequency domain. Frequency domain beamforming is performed between RE mapping and FFT/iFFT processing steps (in UL and DL, respectively) and is therefore essentially a digital operation. Beamforming 540 may be performed in the time domain. Time domain beamforming can be performed in the digital or analog domain. When performed in both the frequency domain and the time domain, beamforming 540 may be referred to as hybrid beamforming. Beamforming 540 performed in the digital domain may be referred to as digital beamforming. Beamforming 540 performed in the analog domain may be referred to as analog beamforming. Beamforming 540 may include at least one of digital beamforming or analog beamforming. Beamforming 540 may include digital beamforming. Beamforming 540 may include analog beamforming. Beamforming 540 may include digital beamforming and analog beamforming.

Implementation of beamforming 540 in RU 220 may be performed in various ways. According to one embodiment, beamforming 540 may be performed based on a predefined beam beamforming method. In the predefined-beam beamforming scheme, 'beamId' can be used to indicate a specific beam to be used in the RU 220. Here, the specific beam may be a frequency-domain beam, a time-domain beam, or a beam using hybrid beamforming.

According to one embodiment, it may be performed based on weight-based dynamic beamforming. DU 210 may generate weights for creating a beam. Accordingly, the DU 210 is required to know the specific antenna characteristics of the RU 220. The specific antenna characteristic may include at least one of the number of antenna elements in the vertical direction, the number of antenna elements in the horizontal direction, or the spacing between antenna elements. The weight vector for each beam may have 'beamId'.

According to one embodiment, it may be performed based on attribute-based dynamic beamforming. DU 210 may instruct RU 220 to use specific beam properties. For example, the beam property may include at least one of an azimuth pointing parameter, a zenith pointing parameter, an azimuth beamwidth parameter, a zenith beamwidth parameter, an azimuth sidelobe parameter, or a zenith sidelobe parameter. Specific beam properties for each beam may be associated with 'beamId'.

According to one embodiment, it may be performed based on a channel information-based beamforming method. If a channel information-based beamforming method is used for at least one layer (or spatial stream), the DU 210 uses the same beamforming method for all layers (or spatial streams) of a specific time-frequency resource element(s). You can use it. Similarly, when an attribute-based dynamic beamforming method is used for one or more layers (or spatial streams), the DU 210 performs the same beamforming for all layers (or spatial streams) of a specific time-frequency resource element(s). method can be used.

(3) Fronthaul interface

At the fronthaul interface between DU 210 and RU 220, the operations of DU 210 and RU 220 are described. As SRS channel estimation 530 is performed in the RU 220 rather than the DU 210, the RU 220 may be required to receive information for SRS channel estimation 530 from the DU 210. The DU 210 may transmit SRS configuration information necessary for SRS channel estimation 530 to the RU 220. The RU 220 may receive a C-plane message 550 including SRS configuration information from the DU 210. According to one embodiment, SRS configuration information may be transmitted from the DU 210 to the RU 220 through section information or section extension information of a C-plane message. RU 220 may obtain SRS configuration information. The RU 220 may perform SRS channel estimation 530 based on SRS configuration information and SRSs 510.

The results of channel estimation can be processed in higher layers. To this end, the RU 220 may transmit channel information to the DU 210. DU 210 may receive a C-plane message 560 including channel information from RU 220. According to one embodiment, channel information may be transmitted from the DU 210 to the RU 220 through section information or section extension information of a C-plane message. For example, the RU 220 may transmit a C-plane message including the result of the SRS channel estimation 530 to the DU 210. RU 220 may report the result of SRS channel estimation 530 to DU 210. The DU 210 or a higher node connected to the DU 210 can perform resource management based on channel information. The DU 210 or a higher node connected to the DU 210 can perform uplink synchronization control based on channel information. The DU 210 or a higher node connected to the DU 210 can obtain channel information based on the channel information.

In FIG. 5 , a series of operations of the DU 210 or the RU 220 on the access network, RU 220, and fronthaul interface are described, but embodiments of the present disclosure are not to be construed as limited to FIG. 5 . Each operation described in FIG. 5 is an example of implementation, and it is not interpreted that the operations of the DU 210 or RU 220 shown in FIG. 5 must be performed together in all embodiments. Operations on the fronthaul interface may be performed in parallel or independently of operations on the access network. Operations of RU 220 may be performed in parallel or independently of operations in the access network. Operations of the RU 220 may be performed in parallel or independently from operations in the fronthaul interface.

Figure 6 shows an example of the functional configuration of a RU for SRS channel estimation, according to embodiments. RU illustrates RU 220 in FIG. 2A. According to one embodiment, RU 220 may include O-RU 253-1. Hereinafter, in FIG. 6, channel information-based beamforming is described as an example. For SRS channel estimation in FIG. 6, the description of SRS channel estimation 530 in FIG. 5 may be referred to. For beamforming in FIG. 6, the description of beamforming 540 in FIG. 5 may be referred to.

Referring to FIG. 6, the RU 220 may receive SRSs from the terminal 120 (eg, UE). The RU 220 may perform UL signal processing 621. The RU 220 may perform UL signal processing 621 for SRSs. UL signal processing 621 may include analog to digital converting (ADC). UL signal processing 621 may include fast fourier transform (FFT) and cyclic prefix (CP) removal. UL signal processing 621 may include RE demapping.

RU 220 may perform SRS channel estimation 530. Instead of SRS channel estimation being performed in DU 210, SRS channel estimation 530 may be performed in RU 220. For SRS channel estimation 530, the RU 220 is required to know information about the generation method of SRS sequences, the mapping method of SRS sequences, and the resources on which SRSs are transmitted. Accordingly, the DU 210 may transmit SRS configuration information for SRS reception and SRS channel estimation 530 to the RU 220. According to one embodiment, the DU 210 may transmit a C-plane message 550 including SRS configuration information for SRS reception and SRS channel estimation 530 to the RU 220. RU 220 may obtain SRS configuration information from DU 210. The RU 220 may perform SRS channel estimation 530 based on SRS configuration information.

RU 220 may generate channel information based on SRS channel estimation 530. For example, the channel information may be 'ciIsample(Ci)' or 'ciQsample(Cq)' of Section Type 6, or may include values obtained from these. Ci represents the in-phase (I) value of complex channel information, and Cq represents the quadrature (Q) value of complex channel information. According to one embodiment, the RU 220 may transmit a C-plane message 560 including channel information to the DU 210. According to one embodiment, the RU 220 may store channel information in the channel memory 625. The channel memory 625 of the RU 220 may store channel information. RU 220 may perform beamforming 540. For example, the RU 220 may perform beamforming 540 based on scheduling information (eg, section information). For the scheduled UE 120, the RU 220 may obtain the stored channel information from the channel memory 625. The RU 220 may perform beamforming 540 based on channel information. For example, the RU 220 can calculate and obtain beamforming weights (or multi-user (MU) weights) for minimum mean square error (MMSE) (or zero forcing beamforming (ZFBF)) for the current channel. there is.

The RU 220 according to embodiments may perform SRS channel estimation 530 to improve the performance of beamforming 540. As SRS channel estimation 530 is performed in the RU 220 rather than the DU 210, the processing delay required to acquire channel information can be shortened. Since beamforming 540 is performed based on channel information at a time point closer to the time point at which SRSs are received, channel information relatively close to actual channel characteristics can be used for beamforming 540. Additionally, the DU 210 does not provide channel information to the RU 220, but the RU 220 directly obtains channel information, thereby reducing fronthaul capacity.

As described above, as SRS channel estimation 530 is performed in RU 220, new C-plane messages 550 and 560 are required to be defined within the fronthaul interface. Hereinafter, C-plane messages for SRS channel estimation 530 in the RU 220 are described in detail with reference to FIG. 7.

Figure 7 shows an example of signaling between DU and RU for SRS channel estimation of RU, according to embodiments. DU illustrates DU 210 in FIG. 2A. According to one embodiment, DU 210 may include O-DU 251. RU illustrates RU 220 in FIG. 2A. According to one embodiment, RU 220 may include O-RU 253-1.

Referring to FIG. 7, in operation 721, the DU 210 may transmit SRS configuration information to the RU 220. DU 210 may generate SRS configuration information. For SRS channel estimation in the RU 220, the DU 210 may provide resource allocation information to the RU 220. Resource allocation information may be configured as UE-specific. According to one embodiment, DU 210 may generate SRS configuration information for an SRS symbol. SRS configuration information may include SRS resource allocation information within the SRS symbol. SRS configuration information may indicate the range of PRBs allocated for SRS transmission within the SRS symbol. SRS configuration information may include section information for each UE to which resources are allocated within the SRS symbol. Accordingly, SRS configuration information may include identification information for each of the UEs.

DU 210 may transmit SRS configuration information to RU 220. According to one embodiment, SRS configuration information may be transmitted based on SRS transmission settings. For example, if SRS is set to be transmitted periodically (e.g., periodic transmission or semi-persistent transmission), the DU 210 may periodically transmit SRS configuration information to the RU 220. there is. SRS configuration information may be generated for at least one SRS symbol that arrives periodically. For another example, when SRS is transmitted aperiodically, the DU 210 may periodically transmit SRS configuration information corresponding to a specific SRS symbol to the RU 220.

SRS configuration information may include parameters related to SRS transmission. SRS configuration information may include parameters for generating an SRS sequence (hereinafter referred to as SRS sequence information) and parameters related to resource allocation of SRSs (hereinafter referred to as SRS resource allocation information). The parameters may be transmitted to the RU 220 through a C-plane message. According to one embodiment, all of the above parameters may be included in section information within the C-plane message. According to another embodiment, at least some of the parameters may be included in section information in the C-plane message, and other parts may be included in section extension information in the C-plane message. Additionally, according to an additional embodiment, some of the above parameters are fixed values and may be omitted within the C-plane message. Hereinafter, the parameters of SRS setting information are described in detail.

SRS configuration information may include parameters necessary for the UE to generate an SRS sequence. SRS configuration information may directly or indirectly include parameters defined in 3GPP to generate an SRS sequence. Here, directly including means that information directly pointing to parameters defined in 3GPP is transmitted through the fronthaul interface. Indirectly including means that information that directly points to parameters defined in 3GPP is indirectly indicated, but information structured in a different way is transmitted through the fronthaul interface.

According to one embodiment, SRS configuration information may include at least one of parameters indicated by transmission comb information. SRS configuration information may include at least one of a comb value, a comb offset, or a cyclic shift value. For example, SRS setting information may include information indicating a comb value. Additionally, for example, SRS configuration information may include information indicating a comb offset. Additionally, for example, SRS configuration information may include information indicating a cyclic shift value.

According to one embodiment, SRS configuration information may include parameters indicated by hopping method information. Hopping method information may indicate group hopping or sequence hopping. SRS configuration information may include a value indicating whether group hopping (or sequence hopping).

According to one embodiment, SRS configuration information may include at least one of sequence information. Sequence information may include at least one of a sequence group number and a sequence number for a base sequence. For example, SRS configuration information may include information indicating 'u'. For example, SRS configuration information may include information indicating 'v'.

SRS configuration information may include parameters related to resource allocation. SRS configuration information may directly or indirectly include parameters defined in 3GPP to generate an SRS sequence. According to one embodiment, SRS configuration information may include at least one of parameters indicated by transmission type information. SRS configuration information may include at least one of a parameter, period, or offset indicating whether SRS transmission is periodic, semi-persistent, or aperiodic. For example, SRS configuration information may include information indicating whether SRS transmission is periodic, semi-permanent, or aperiodic. Additionally, for example, SRS configuration information may include information indicating the transmission cycle. Additionally, for example, SRS configuration information may include information indicating a transmission offset. Meanwhile, according to another embodiment, the SRS configuration information provided in the fronthaul interface is provided in symbol units, so parameters indicating temporal resources may be omitted. For example, parameters representing time domain behavior of SRS may not be included in SRS configuration information.

According to one embodiment, SRS configuration information may include at least one of parameters indicated by frequency domain information. The SRS configuration information may include at least one of a frequency domain shift value or a frequency position parameter in the frequency domain when allocating an SRS. For example, SRS configuration information may include information indicating a frequency domain shift value. Additionally, for example, SRS configuration information may include information indicating a frequency location parameter.

According to one embodiment, SRS configuration information may include at least one of parameters indicated by resource mapping information. The SRS configuration information may include at least one of the position of the SRS symbol to which SRS sequences are mapped (e.g., position from the last symbol of the slot), the number of SRS symbols, or a repetition factor. For example, SRS setting information may include information indicating the location of the SRS symbol. Additionally, for example, SRS configuration information may include information indicating the number of SRS symbols. Additionally, for example, SRS setting information may include information indicating a repetition factor.

According to one embodiment, SRS configuration information may include at least one of parameters indicated by frequency hopping information. The SRS configuration information may include at least one of the parameters for SRS frequency hopping (e.g., C _SRS , B _SRS , and b _hop in 3GPP TS 38.211). For example, SRS configuration information may include information indicating 'C _SRS '. For example, SRS configuration information may include information indicating 'B _SRS '. For example, SRS configuration information may include information indicating 'b _hop '.

According to one embodiment, SRS configuration information may include at least one of parameters indicated by partial frequency sounding information. Partial frequency sounding means allowing SRS transmission on partial frequency resources within legacy SRS frequency resources in order to provide more flexibility in SRS transmission. SRS configuration information may include at least one of a starting RB index, a frequency scaling factor, or an indicator for enabling RB hopping. For example, SRS configuration information may include a start RB index. For example, SRS configuration information may include a frequency scaling factor. For example, SRS configuration information may include an indicator for RB hopping activation.

At operation 723, RU 220 may generate an SRS channel estimate and SRS channel information. According to one embodiment, the RU 220 may perform channel estimation based on SRSs received from the UE 120. To calculate beamforming weights in the RU 220, the RU 220 may perform channel estimation for the uplink based on SRSs. The RU 220 may perform channel estimation for the uplink channel for each UE.

According to one embodiment, the RU 220 may generate SRS channel information based on the result of the channel estimation. The SRS channel information may include one or more parameters obtained as a result of channel estimation of the RU 220. For example, the SRS channel information may be generated UE-specifically. Channel information may include channel information values of in-phase samples and channel information values of quadrature samples. The SRS channel information may include a channel information I value and a channel information Q value per unit resource (eg, SRS symbol, PRB). Additionally, for example, the SRS channel information may include a time offset value. Time offset is related to uplink synchronization and can be measured based on SRS. Additionally, for example, the SRS channel information may include an indicator indicating channel quality. Channel quality can be measured based on SRS. Additionally, for example, the SRS channel information may include a parameter indicating the range of PRBs for which channel information is reported. Channel information may not be reported for all PRBs, but channel information may be reported for some PRBs among all PRBs.

According to one embodiment, all parameters of the SRS channel information may be included in section information within the C-plane message. According to another embodiment, at least some of the parameters may be included in section information in the C-plane message, and other parts may be included in section extension information in the C-plane message. Additionally, according to an additional embodiment, some of the above parameters are fixed values and may be omitted within the C-plane message.

In operation 725, RU 220 may transmit SRS channel information to DU 210. The results of the channel estimation of the RU 220 may be used by network entities supporting higher layers. For example, the results of channel estimation may be used for scheduling or radio resource management for terminals served by the RU 220. Accordingly, the RU 220 may transmit channel information estimated from the SRS to the DU 210 for each slot. The RU 220 may store the SRS channel information generated in operation 723 in the channel memory of the RU 220. Accordingly, when reporting SRS channel information, the RU 220 may extract the SRS channel information stored in the channel memory and transmit the extracted SRS channel information to the RU 220.

After channel estimation is completed, the RU 220 may transmit SRS channel information to the DU 210. There may be a time interval from receiving the SRS configuration information at the RU 220 to transmitting the SRS report. After the RU 220 performs channel estimation in operation 723, a time interval may be required to prepare an SRS report. Considering the capacity of the fronthaul interface between the DU 210 and the RU 220 and the computational burden of the RU 220, reporting of SRS channel information of the RU 220 may be performed in parallel. That is, each operation described in FIG. 7 is an example of implementation, and in all embodiments, it is interpreted that the operations of the DU 210 or RU 220 shown in FIG. 7 must be performed sequentially. It doesn't work. According to one embodiment, operations 721 and 723 may be performed in parallel or independently from operation 725.

Since the RU 220 performs SRS channel estimation, the RU 220 may not transmit the C-plane message of section type '1' for transmitting the received SRSs to the DU 210. At the same time that the processing delay for SRS channel estimation is reduced, the burden on the fronthaul interface between the DU 210 and the RU 220 can be reduced. In addition, instead of the DU 210 providing channel information to the RU 220, the RU 220 directly performs channel estimation and delivers the results of the channel estimation to the DU 210, thereby reducing the burden on the fronthaul interface. This may also decrease.

Although not shown in FIG. 7, management-plane (M-plane) parameters between the DU 210 and the RU 220 may be defined. According to one embodiment, the M-plane parameter may include capability information indicating whether SRS channel estimation is possible in the RU 220. The RU 220 may transmit an M-plane message including the capability information to the DU 210. The DU 210 can identify that SRS channel estimation is possible in the RU 220 through the capability information. . If SRS channel estimation is possible in the RU 220, the DU 210 may transmit the newly defined C-plane message in operation 721 to the RU 220. If SRS channel estimation is possible in the RU 220, the DU 210 may receive a C-plane message newly defined in operation 723 from the RU 220. M-plane parameters according to embodiments of the present disclosure are described in detail through FIG. 10.

Figure 8 shows an example of a control plane (C-plane) message including SRS configuration information according to an embodiment. In Figure 8, an example of a C-plane message including SRS configuration information is described. SRS configuration information can be used for SRS channel estimation. DU 210 may transmit SRS configuration information for SRS channel estimation. According to one embodiment, a DU (e.g., DU 210, O-DU 251) sends a C-plane message for each of the SRS symbols to a RU (e.g., RU 220, O-RU 253-1). )) can be sent to. The DU 210 may transmit SRS configuration information for each UE of all UEs related to the SRS symbol to the RU 220. FIG. 8 illustrates a C-plane message including SRS configuration information in operation 721.

Referring to FIG. 8, the C-plane message 800 may include section information 810. According to one embodiment, for the C-plane message 800 containing new section information 810, a new section type (e.g., Section type 8, 9, 10, ..., xx) may be defined. . Before explaining the section information 810, header information included in the C-plane message 800 is described.

The C-plane message 800 may include a transport header (eg, eCPRI header or IEEE 1914.3) information. Transport headers may include 'ecpriVersion', 'ecpriReserved, 'ecpriConcatenation', 'ecpriMessage', 'ecpriPayload', 'ecpriRtcid/ecpriPcid', and 'ecpriSeqid', as described above.

The C-plane message 800 may include common header information. Common header information is 'dataDirection' indicating the data transmission direction of the base station (e.g. gNB), 'payloadVersion' indicating the valid payload protocol version of IEs in the application layer, and the channel between IQ data and air interface to be used in both DL and UL. It can include 'filterindex', which means the index for the filter (channel filter).

Common header information may include information indicating the location of time resources to which the C-plane message 800 is applicable. The location of a time resource may be indicated by a frame, subframe, slot, or symbol. Common header information may include 'frameId' indicating a frame number, 'subframeId' indicating a subframe number, 'slotId' indicating a slot number, and 'startSymbolId' indicating a symbol number. The frame is determined based on arithmetic modulo 256. A subframe has units of 1ms included in a 10ms frame. Slot numbers are numbered within the subframe, and the maximum size can be 1, 2, 4, 8, or 16 depending on the numerology.

Common header information may include 'numberOfsections' indicating the number of data sections included in the C-plane message 800. Common header information may include 'sectionType' that determines the characteristics of U-plane data. Common header information may include 'udCompHdr' to indicate compression method and bit width in uplink.

(1) Section Type

C-plane message 800 may include section information 810. Section information 810 may be used to indicate settings for SRS channel estimation of the RU 220. Hereinafter, to describe the SRS channel estimation of the RU 220, the term SRS configuration is used, but other terms (e.g., SRS setup, SRS setting) that have the same technical meaning are used. It could also be used instead.

Section information 810 may include 'sectionId', which means a section identifier. When C-Plane and U-Plane coupling via 'sectionId' is used, 'sectionId' identifies an individual data section described by the data section description in the C-Plane message 800. The purpose of 'sectionId' is to map U-Plane data sections to the corresponding C-Plane messages (and section types) 800 associated with the data. Section information 810 includes 'rb' indicating whether all RBs are used (every RB is used) or every other RB (every other RB), and 'symInc' indicating a symbol number increment command. ', 'startPrbc' to indicate the start PRB number of the data section description, 'numPrbc' to indicate the number of consecutive PRBs per data section description, and 'ef' to indicate the extension flag. can do.

Section information 810 according to embodiments may include SRS sequence generation information and SRS resource information of each UE transmitting SRS in an SRS symbol. For example, when the number of UEs performing SRS transmission in the SRS symbol is plural, the C-plane message 800 may include SRS sequence generation information and SRS resource information for each of the plurality of UEs. Additionally, for example, when one UE performs SRS transmission in the SRS symbol, the C-plane message 800 may include SRS sequence generation information and SRS resource information for the one UE. Here, the section information 810 may include UE identification information of each UE. Within the section information 810, SRS sequence generation information and SRS resource information for the corresponding UE may be identified based on UE identification information (or UE identifier) ('ueId').

Section information 810 according to embodiments may include parameters necessary for SRS channel estimation in the RU 220. For SRS channel estimation, the RU 220 is required to know how to generate SRS sequences transmitted by the UE. The SRS sequence can be generated based on the following equations.

here, represents the number of SRS subcarriers in the frequency domain, that is, the bandwidth. represents the number of SRS symbols. α _i represents a cyclic shift. p _i represents the antenna port. Is represents the comb value. represents a sequence group, represents the sequence number.

represents the cyclic shift value in the RRC parameter 'transmissionComb' IE, represents the maximum value of the cyclic shift. N _ap ^SRS indicates the number of antenna ports.

Can be identified within the table specified by the RRC parameters C _SRS and B _SRS . represents the number of subcarriers per RB (e.g., 12). represents the number of SRS symbols.

According to one embodiment, section information 810 may include comb type information ('csCombType'). Comb type information may indicate a comb value. For example, the comb value may correspond to the value indicated by transmission comb IE in SRS-Config, an RRC parameter of 3GPP. The comb value can be 2, 4, or 8. As an example, comb type information may indicate a comb value and a cyclic shift value as shown in the table below.

csCombType Remarks 00b comb value: 2, number of CS (maximum value): 8 01b comb value: 4, number of CS (maximum value): 12 10b comb value: 8, number of CS (maximum value): 6 11b reserved

According to one embodiment, the section information 810 may include information ('u') about the sequence group number. Base sequences can be divided into groups. At this time, the sequence group number indicates the group number. Each group has a first scope, e.g. , ) and a second range (sequence number: 0) with a length of , ) may contain two basic sequences (sequence numbers: 0, 1) with a length of For example, the sequence group number is 3GPP's can point to can have an integer value between 0 and 29. As an example, information about the sequence group number may be indicated by 5 bits.

According to one embodiment, the section information 810 may include information ('v') about the sequence number. Sequence number may refer to a sequence number within a group. For example, the sequence number is 3GPP's can point to can be 0 or 1. As an example, information about the sequence number may be indicated by 1 bit.

According to one embodiment, the section information 810 may include information about the comb offset ('comb'). Comb offset can be used to indicate the location of the frequency domain in RE mapping of SRS symbols. For example, the comb offset may be a value indicated by the transmission comb IE of 3GPP. The comb offset corresponds to an integer value in the range of 0 to 0 and less than the 'comb value'. As an example, information about the sequence number may be indicated by 3-bits. As another example, information about the sequence number may be indicated by 4-bits.

According to one embodiment, section information 810 may include cyclic shift information ('cs'). Cyclic shift information indicates a cyclic shift value for the UE. The cyclic shift value may provide phase rotation to give orthogonality to the UE's signal in SRS sequence generation. For example, the cyclic shift value may be a value indicated by 3GPP's transmission comb IE. The cyclic shift value has different ranges depending on the comb value. When the comb value is 2, the cyclic shift value is an integer value between 0 and 7. When the comb value is 4, the cyclic shift value is an integer value between 0 and 11. If the comb value is 8, the cyclic shift value is an integer value between 0 and 5. As an example, information about the sequence number may be indicated by 4-bits.

According to one embodiment, section information 810 may include information about a repetition factor ('repetitionFactor'). The repetition factor can be used in the RE mapping of SRS symbols to count SRS symbols in the time domain. For example, the repetition factor may be a value indicated by the repetitionfactor IE of 3GPP. The repetition factor can be 1, 2, or 4. As an example, information about the repetition factor may be indicated by 2-bits. As another example, information about the repetition factor may be indicated by 4-bits.

According to one embodiment, section information 810 may include UE identification information (or UE identifier) ('ueId'). UE identification information indicates the label of the UE to which section contents apply. As an example, UE identification information may be indicated by 15-bits.

(2) Section Extension

The C-plane message 800 may additionally include section extension information 820. That is, the C-plane message 800 may additionally include section information 810 and section extension information 820. Section extension information 820 may include 'extType', which provides a new extension type (eg, 0xpp). Section extension information may include 'ef' indicating whether there is another extension present or whether the current extension field is the last extension. Section extension information may include 'extLen', which provides the length of the section extension in 32-bit (or 4-byte) words.

To configure SRS for multiple UEs rather than one UE, section extension information 820 may be additionally included in the C-plane message 800. For example, two UEs may be multiplexed within the same sections (time-frequency resource range). At this time, multiplexing for UEs can be implemented through different cyclic shift values. According to one embodiment, the section extension information 820 may include cyclic shift information ('cs') indicating a cyclic shift value for a UE other than the UE in the section information 810. As the cyclic shift value for the other UE is applied to the other UE, the UE of section information 810 and the other UE may be multiplexed. For the cyclic shift information for the other UE, the description of the cyclic shift information ('cs') of the section information 810 may be referred to. Additionally, the section extension information 820 may include UE identification information (or UE identifier) ('2 ^nd ueId') to indicate the other UE.

According to one embodiment, the section extension information 820 may include extension number information indicating the number of UEs being multiplexed. The extended number information may indicate the number of additional cyclic shift fields. For example, in FIG. 8, since two UEs are multiplexed, the extension number information may indicate 1. Although not shown in FIG. 8, as another example, when the extension number information is 1, the extension number information may be omitted from the section extension information 820.

In FIG. 8, information other than the cyclic shift field value and extension number information of another UE (hereinafter referred to as the second UE) is described as being included in the section information 810, but embodiments of the present disclosure are not limited thereto. According to another embodiment, at least some of the information in the section information 810 shown in FIG. 8 may be included in the section extension information 820. For example, a section extension for SRS channel estimation in the RU 220 may be added to the existing section type C-plane message.

In Figure 8, the parameters required for SRS channel estimation in the RU 220 are shown. However, the parameters shown in FIG. 8 are one embodiment, and the embodiments of the present disclosure are not necessarily limited to including all the parameters shown in FIG. 8. In some embodiments, at least some of the parameters shown in Figure 8 may be omitted. Additionally, in some embodiments, at least some of the parameters shown in FIG. 8 may indicate their values in a manner different from the description above. Additionally, in FIG. 8, the C-plane message according to the new section type (or new section type and new section extension type) is described, but the description does not exclude providing the parameters to the RU 220 through other methods. . According to one embodiment, at least some of the fields described above may be provided through reserved fields of an existing C-plane message.

In FIG. 8, section information 810 and section extension information 820 of the C-plane message 800 are shown together, but other embodiments of the present disclosure may not be limited thereto. According to one embodiment, the C-plane message 800 may include only section information 810 without section extension information 820. Additionally, a C-plane message in which the section extension information 820 is added to section information 810 and other section information of the C-plane message 800 may also be understood as an embodiment of the present disclosure.

In Figure 8, section extension information 820 for multiplexing of two UEs is described. However, the two UEs are only one embodiment, and other embodiments of the present disclosure are not limited thereto. Hereinafter, in FIG. 9, an example of section extension information when not only two UEs but also three or more UEs are multiplexed is described.

In Figure 8, C-plane messages for individual SRS symbols are described. When SRS transmission is performed over a plurality of SRS symbols, according to one embodiment, the DU 210 may transmit a C-plane message for each SRS symbol among the plurality of SRS symbols to the RU 220. . Meanwhile, unlike FIG. 8, according to one embodiment, the DU 210 may transmit a C-plane message for the plurality of SRS symbols to the RU 220. At this time, information indicating the number of symbols (e.g., numSymbol IE) (not shown) may be included in the C-plane message.

Figure 9 shows an example of SRS multiplexing information for each UE according to an embodiment. The same frequency resource can be allocated to multiple UEs through cyclic shifting. For multiplexing through cyclic shift, SRS multiplexing information may be added to a C-plane message (e.g., C-plane message 920) through section extension.

Referring to FIG. 9, section extension information 920 may be added to a C-plane message (eg, C-plane message 920). Section extension information 920 may include 'extType', which provides a new extension type (eg, 0xpp). Section extension information may include 'ef' indicating whether there is another extension present or whether the current extension field is the last extension. Section extension information may include 'extLen', which provides the length of the section extension in 32-bit (or 4-byte) words.

According to one embodiment, section extension information 920 may include extension number information indicating the number of UEs being multiplexed. The extended number information may indicate the number of additional cyclic shift fields. As an example, M UEs may be multiplexed. The extended number information may indicate M-1. UEs may transmit orthogonal SRSs on the same frequency resource through different cyclic shift values. The range of the cyclic shift value may be determined depending on the comb type. For example, if the comb value is 2, the cyclic shift value is an integer value between 0 and 7. The maximum number of UEs that can be multiplexed can be determined to be 8. When the comb value is 4, the cyclic shift value is an integer value between 0 and 11. The maximum number of UEs that can be multiplexed can be determined to be 12. If the comb value is 8, the cyclic shift value is an integer value between 0 and 5. The maximum number of UEs that can be multiplexed can be determined to be 6.

According to one embodiment, section extension information 920 may include SRS multiplexing information for each UE. As an example, M UEs may be multiplexed. Section extension information 920 may include M-1 pieces of multiplexing information. The ith (i is an integer from 1 to M-1) SRS multiplexing information includes UE identification information ('2nd ueId', '3rd ueId', or '(numCsExt+1)th ueId to indicate the i+1th UE ') and cyclic shift information for the i+1th UE ('cs (for 2nd ueId)', 'cs (for 3rd ueId)', or 'cs (for (numCsExt+1)th ueId')). You can. In addition, the ith multiplexing information includes information about the repetition factor for the i+1th UE ('repetitionFactor (for 2nd ueId)', 'repetitionFactor (for 3rd ueId)', or 'repetitionFactor (for (numCsExt+1)th ueId ')) may be included. For information on the UE identification information, the cyclic shift information, and the repetition factor, descriptions of the UE identification information, the cyclic shift information, and information on the repetition factor in FIG. 8 may be referred to.

As an example, UE identification information may be indicated by 2-bytes. Cyclic shift information can be indicated by 4-bit. Information about the repetition factor can be indicated by 4-bit. In this case, 3-bytes of SRS multiplexing information may be required per UE added for multiplexing. Therefore, the length of the section extension information 920 (e.g., extLen field value) is: It can be determined as a value corresponding to . here, may indicate the number of SRS multiplexing information indicated by the extended number information.

In some embodiments, the section extension information 920 may further include filler information ('filler to ensure 4-byte boundary'). The filler information may include designated information (eg, dummy bits) so that the section extension information 920 is generated in 4-byte units. for example, If is not a multiple of 4, the section expansion information 920 may further include filler information. Meanwhile, according to another embodiment, the section expansion information 920 may not include the filler information. for example, If it is a multiple of 4, the section expansion information 920 may not include the filler information.

Figure 10 shows an example of SRS channel information according to one embodiment. In Figure 10, an example of a C-plane message including SRS channel information is described. The RU can provide the results of SRS channel estimation to the upper layer through SRS channel information. According to one embodiment, a DU (e.g., DU 210, O-DU 251) sends a C-plane message including SRS channel information to a RU (e.g., RU 220, O-RU 253-1). )) can be sent to. 10 illustrates a C-plane message containing SRS configuration information in operation 725.

Referring to FIG. 10, the C-plane message 1000 may include section information 1010. According to one embodiment, for the C-plane message 1000 including section information 1010, a section type (eg, Section type 6) for carrying channel information may be used. However, the C-plane message 100 may be transmitted from the RU 220 to the DU 210. The RU 220 may transmit channel information stored in the channel memory of the RU 220 to the DU 210. Hereinafter, before explaining the section information 1010, header information included in the C-plane message 1000 is described.

The C-plane message 1000 may include a transport header (eg, eCPRI header or IEEE 1914.3) information. Transport headers may include 'ecpriVersion', 'ecpriReserved, 'ecpriConcatenation', 'ecpriMessage', 'ecpriPayload', 'ecpriRtcid/ecpriPcid', and 'ecpriSeqid', as described above.

The C-plane message 1000 may include common header information. Common header information is 'dataDirection' indicating the data transmission direction of the base station (e.g. gNB), 'payloadVersion' indicating the valid payload protocol version of IEs in the application layer, and the channel between IQ data and air interface to be used in both DL and UL. It can include 'filterindex', which means the index for the filter (channel filter).

Common header information may include information indicating the location of time resources to which the C-plane message 1000 is applicable. The location of a time resource may be indicated by a frame, subframe, slot, or symbol. Common header information may include 'frameId' indicating a frame number, 'subframeId' indicating a subframe number, 'slotId' indicating a slot number, and 'startSymbolId' indicating a symbol number. The frame is determined based on arithmetic modulo 256. A subframe has units of 1ms included in a 10ms frame. Slot numbers are numbered within the subframe, and the maximum size can be 1, 2, 4, 8, or 16 depending on the numerology.

Common header information may include 'numberOfsections' indicating the number of data sections included in the C-plane message 1000. Common header information may include 'sectionType' that determines the characteristics of U-plane data. Common header information may include 'udCompHdr' to indicate compression method and bit width in uplink.

According to embodiments, the C-plane message 1000 transmitted from the RU 220 to the DU 210 may include section information 1010. Section information 1010 may indicate channel IQ values for each UE.

According to one embodiment, section information 1010 may include UE identification information (or UE identifier) ('ueId'). UE identification information indicates the UE associated with section information 1010. As an example, UE identification information may be indicated by 15-bits. Additionally, according to one embodiment, the section information 1010 may include regularization information ('regularizationFactor'). Normalization information may indicate a regularization factor for beamforming. For example, the normalization factor may be used to calculate a beamforming weight using the MMSE of the RU 220. As an example, normalization information may be indicated by 2-bytes (i.e., 16-bits). Additionally, according to one embodiment, the section information 1010 includes 'rb', a symbol number increment command, indicating whether all RBs are used (every RB is used) or every other RB (every other RB) is used. 'symInc' meaning (command), 'startPrbc' indicating the start PRB number of the data section description, 'numPrbc' indicating the number of PRBs per data section description, indicating the extension flag. May include 'ef' for.

According to one embodiment, section information 1010 may include channel information. Channel information may refer to channel coefficients calculated by SRSs. Channel information may include channel IQ values for the UE (eg, ueId) of the corresponding section. The channel IQ values are the channel information value of the in-phase sample (hereinafter, channel information I value) ('ciIsample') and the channel information value of the quadrature sample (hereinafter, channel information Q value) ( 'ciQsample'). For example, channel information may include a channel information I value and a channel information Q value per unit resource (e.g., SRS symbol, PRB).

According to one embodiment, one C-plane message may be generated for multiple UEs to which the same SRS symbol is assigned. One C-plane message may include multiple section information. A UE in each section may be one of a plurality of UEs assigned the same SRS symbol. Channel information in each section may include the channel IQ value of the corresponding UE.

The RU 220 according to embodiments may use a new type of section extension information 1020 for additional channel information in addition to the channel IQ value. Section expansion information 1020 may be added to section information. The C-plane message 1000 may additionally include section extension information 1020. That is, the C-plane message 1000 may additionally include section information 1010 and section extension information 1020. Section extension information 1020 may include 'extType', which provides a new extension type (eg, 0xYY). Section extension information may include 'ef' indicating whether there is another extension present or whether the current extension field is the last extension. Section extension information may include 'extLen', which provides the length of the section extension in 32-bit (or 4-byte) words.

According to one embodiment, section extension information 1020 may include PRB interval information ('intervalPrbc'). PRB interval information refers to the interval between PRBs for which channel information is reported. For example, PRB section information may be 1. Channel information for each of all PRBs may be reported. However, when channel information for all PRBs is reported, the fronthaul bandwidth between the DU 210 and the RU 220, which is proportional to the total number of PRBs, can be used. To reduce fronthaul bandwidth within limited capacity, reporting may be performed for some PRBs at equal intervals rather than consecutive PRBs. For example, the PRB interval information may be greater than 1 (i.e., intervalPrbc>1). PRBs reported may not be consecutive. Fronthaul bandwidth may be reduced. As an example, the PRB interval information may be indicated by 6 bits.

The range of PRBs reported by section extension information 1020 may be determined based on 'startPrbc' and 'numPrbc' indicated in section information 1010. 'startPrbc' may indicate the number of the start PRB of the range of PRBs reported. 'numPrbc' indicates the number of PRBs reported. For example, the range of PRBs reported can be expressed as the following equation.

Here, PRB range indicates the range of PRBs reported. For example, if 'startPrbc' is 6, 'numPrbc' is 4, and 'intervalPrbc' is 3, the range of PRBs reported is [6,9,12,15].

According to one embodiment, section extension information 1020 may include channel quality information ('snr'). RU 220 may perform channel estimation based on the received SRSs. RU 220 may perform channel estimation for each UE. Through channel estimation, the RU 220 can obtain the channel quality of the uplink channel. For example, uplink channel quality may be a signal to noise ratio (SNR) value for the received SRSs. The RU 220 may obtain the SNR value for each UE. As an example, the SNR value may be indicated by 16 unsigned bits. Meanwhile, in FIG. 10, SNR is illustrated as the channel quality, but embodiments of the present disclosure are not limited thereto. For channel quality, SNR and other metrics may be used. Channel quality includes, for example, reference signal received power (RSRP) (i.e., SRS-RSRP), reference signal received quality (RSRQ), received signal strength indicator (RSSI), signal to interference and noise ratio (SINR), and CINR. It may be at least one of (carrier to interference and noise ratio), error vector magnitude (EVM), bit error rate (BER), or block error rate (BLER). Of course, in addition to the above examples, other terms with equivalent technical meanings or other indicators indicating channel quality may be used.

According to one embodiment, section extension information 1020 may include time offset information ('timeOffset'). The RU 220 may perform uplink synchronization based on the received SRSs. The RU 220 may obtain uplink synchronization for each UE through channel estimation. RU 220 may obtain a time offset calculated according to channel estimation. The time offset may represent the difference between the transmission start time of the SRS and the reception time of the base station (e.g., RU 220). The time offset may be used to control timing advance (TA) of the corresponding UE. As an example, the value of the time offset may be indicated by signed 16 bits.

According to one embodiment, the section extension information 1020 may include validity information ('validToe'). Validity information indicates the validity of the time offset estimate. For example, the value '0' of the validity information may indicate invalid. The value '1' of the validity information may indicate validity. As an example, the validity information may be indicated by 1 bit.

In FIG. 10, section information 1010 and section extension information 1020 of the C-plane message 1000 are shown together, but other embodiments of the present disclosure may not be limited thereto. According to one embodiment, the C-plane message 1000 may include only section information 1010 without section extension information 1020. Additionally, a C-plane message in which the section extension information 1020 is added to section information 1010 and other section information of the C-plane message 1000 may also be understood as an embodiment of the present disclosure.

11A and 11B show examples of SRS channel estimation according to a management plane (M-plane) message, according to one embodiment. Hereinafter, to describe the SRS channel estimation of the RU 220, the term SRS configuration is used, but other terms (e.g., SRS setup, SRS setting) that have the same technical meaning are used. It could also be used instead.

Referring to FIG. 11A, DU 1101 and RU 1102 represent conventional DUs and RUs, respectively, that do not support the SRS channel estimation technique in the RU of the present disclosure. The DU (1101) may transmit a C-plane message (e.g., C-plane message of Section type 1) containing information about SRS symbols (e.g., SRS symbol info.) to the RU (1102). You can. RU 1102 may receive SRSs from the UE. DU 1101 may perform SRS channel estimation 1130 based on SRSs. The DU 1101 may transmit channel information generated based on the result of the SRS channel estimation 1130 to the RU 1102. The RU 1102 may perform beamforming 1140 based on the received channel information.

DU 210 and RU 220 represent DUs and RUs that support the SRS channel estimation technique in the RU of the present disclosure, respectively. RU 220 may receive SRSs from the UE. The RU 220 may not transmit a message including the received SRSs to the DU 210. The RU 220 may receive a C-plane message including setup information for SRS channel estimation, that is, SRS setup information (eg, SRS setup info.) from the DU 210. The RU 220 may perform SRS channel estimation 530 based on the C-plane message and SRSs. RU 220 may generate channel information based on SRS channel estimation 530. For example, channel information may be stored in channel memory. The RU 220 may perform beamforming 540 based on channel information. Unlike the RU 1102, the RU 220 performs beamforming 540 based on the channel information stored in the channel memory without waiting for separate reception of channel information, thereby performing beamforming that more closely reflects actual channel characteristics. Weights can be obtained. Independently of the beamforming 540, the RU 220 may transmit the generated channel information to the RU 1102.

<M-plane>

Comparing the DU 210 and RU 220 with the DU 1101 and RU 1102, messages transmitted on the fronthaul interface vary depending on which entity supports SRS channel estimation. Accordingly, the DU 210 and the RU 220 according to embodiments may perform a negotiation procedure to indicate whether the RU 220 supports the SRS channel estimation function. The negotiation procedure may be performed in the management plane (M-plane).

According to one embodiment, the RU 220 may transmit an M-plane message including capability information of the RU 220 to the DU 210. For example, the capability information of the M-plane message may include a parameter (eg, 'srs-ce-supported') indicating that the RU 220 supports the SRS channel estimation function. For example, according to yang.Module of M-plane, 'o-ran-module-cap > module-capability > ru-capabilities > "srs-ce-supported"' may be set. The value of 'srs-ce-supported' of the RU 220 that supports the SRS channel estimation function may be set to 'true'. The DU 210 can query the 'srs-ce-supported' of the RU 220 connected to the DU 210. The DU 210 may identify whether the RU 220 connected to the DU 210 supports the SRS channel estimation function.

According to one embodiment, the DU 210 may transmit to the RU 220 an M-plane message including a parameter (e.g., srs-ce-activation) indicating that the SRS channel estimation function is performed in the RU 220. there is. After checking the capabilities of the RU 220, the DU 210 may inform the RU 220 whether to provide the SRS channel estimation function of the RU 220. The RU 220 may identify that the SRS channel estimation function is activated in the RU 220 through the above parameter. Meanwhile, the parameter indicating that the SRS channel estimation function is performed in the RU 220 may be transmitted through a field of the C-plane message, unlike the M-plane message. For example, SRS setting information described through FIGS. 7 to 9 (e.g., SRS setting information in operation 721 of FIG. 7), section information (e.g., section information 810), or section expansion information (e.g. : As section extension information 820 and section extension information 920) are provided, the RU 220 can identify that the SRS channel estimation function is performed in the RU 220. For another example, a separate field indicating that the SRS channel estimation function is performed in the RU 220 may be defined. The RU 220 can identify from the field that the SRS channel estimation function is performed in the RU 220.

Referring to FIG. 11B, the RU 220 may support an SRS channel estimation function. The DU 210 may determine whether to provide the SRS channel estimation function to the RU 220. According to one embodiment, the DU 210 may transmit to the RU 220 an M-plane message including a parameter indicating that the SRS channel estimation function is performed in the RU 220. The RU 220 may perform SRS channel estimation 530 and beamforming 540, as shown in FIG. 11A. Additionally, the RU 220 may report estimated channel information to the DU 210.

Conversely, the DU 210 may transmit to the RU 220 an M-plane message including a parameter indicating that the SRS channel estimation function is not performed in the RU 220. That is, the SRS channel estimation function may be disabled in the RU 220. Although the RU 220 supports the SRS channel estimation function, the RU 220 may not perform SRS channel estimation. Like the DU 1001, the DU 210 may transmit a C-plane message (e.g., a C-plane message of Section type 1) containing information about the SRS symbol to the RU 220. Like the RU 1002, the RU 220 may transmit a U-plane message including the received SRSs to the DU 210. The DU 210 may transmit a C-plane message (e.g., C-plane message of Section type 6) including channel information to the RU 220. The RU 220 may perform beamforming 1140 based on the channel information.

In FIGS. 11A and 11B, M-plane parameters for whether to support the SRS channel estimation function and whether to provide the SRS channel estimation function are described, but embodiments of the present disclosure are not limited thereto. Among the parameters described in FIGS. 7 to 10, values for recommendations may be transmitted through an M-plane message.

According to one embodiment, the DU 210 may transmit an M-plane message including reporting interval information (eg, srs-ce-report-prb-interval) to the RU 220. The DU 210 may transmit reporting interval information to the RU 220 in order to adjust the amount of channel information required in the L2 layer. The reporting interval information may correspond to PRB interval information ('intervalPrbc') included in the section extension information 1020 of FIG. 10. The reporting interval information may be a value recommended (or set) by the DU 210 to the RU 220. The RU 220 may determine the interval between reported PRBs based on the reporting interval information.

Figure 12 shows examples of SRS channel estimation according to RU capability according to one embodiment. In Figure 12, a situation where a RU that supports the SRS channel estimation function and performs SRS channel estimation, a RU that supports the SRS channel estimation function but does not perform SRS channel estimation, and a RU that does not support the SRS channel estimation function are connected to the DU. This is exemplified.

Referring to FIG. 12, DU 1200 may be connected to a plurality of RUs. For the DU 1200, reference may be made to the description of the DU 210 in FIG. 2A or the description of the O-DU 251 in FIG. 2B. The plurality of RUs may include a first RU (1201), a second RU (1203), a third RU (1205), and a fourth RU (1207). For each RU, reference may be made to the description of the RU 220 in FIG. 2A or the description of the O-RU 253-1 in FIG. 2B.

The first RU 1201 may support an SRS channel estimation function. For example, the M-plane parameter 'srs-ce-supported' value may be set to 'true'. The first RU 1201 may perform an SRS channel function. The DU 1200 may inform the first RU 1201 that the first RU 1201 will perform SRS channel estimation. According to one embodiment, the DU 1200 may transmit, to the first RU 1201, an M-plane message including information indicating that SRS channel estimation in the first RU 1201 is activated. According to embodiments of the present disclosure, the DU 1200 may transmit SRS configuration information (e.g., SRS configuration information in operation 721) to the first RU 1201. Additionally, the first RU 1201 may transmit SRS channel information (eg, SRS channel information in operation 725) to the DU 1200.

The second RU 1203 may support the SRS channel estimation function. For example, the M-plane parameter 'srs-ce-supported' value may be set to 'true'. The second RU 1203 may not perform the SRS channel function. The DU 1200 may inform the second RU 1203 that SRS channel estimation is not performed in the second RU 1203. According to one embodiment, the DU 1200 sends an M-plane message to the second RU 1203, including information indicating that SRS channel estimation in the second RU 1203 is not activated (or deactivated). can be transmitted. The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 1) including SRS symbol information (e.g., SRS symbol info.) to the second RU 1203. The second RU 1203 may receive SRSs based on the C-plane message. The second RU (1203) may transmit a U-plane message including SRS data corresponding to the SRSs to the DU (1200). Although not shown in FIG. 12, the DU 1200 may generate channel information based on the results of SRS channel estimation performed by the DU 1200. The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 6) including the generated channel information to the second RU 1203.

The third RU 1205 may not support the SRS channel estimation function. The third RU 1205 cannot perform the SRS channel function. For example, the M-plane parameter 'srs-ce-supported' value may be set to 'false', or the M-plane parameter may be invalid (i.e., N/A (non available)). The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 1) including SRS symbol information (e.g., SRS symbol info.) to the third RU 1205. The third RU 1205 can receive SRSs based on the C-plane message. The third RU 1205 may transmit a U-plane message including SRS data corresponding to the SRSs to the DU 1200. Although not shown in FIG. 12, the DU 1200 may generate channel information based on the results of SRS channel estimation performed by the DU 1200. The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 6) including the generated channel information to the third RU 1205.

The fourth RU 1207 may not support the SRS channel estimation function. The fourth RU 1207 cannot perform the SRS channel function. For example, the M-plane parameter 'srs-ce-supported' value may be set to 'false', or the M-plane parameter may be invalid (i.e., N/A). The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 1) including SRS symbol information (e.g., SRS symbol info.) to the fourth RU 1207. The fourth RU 1207 can receive SRSs based on the C-plane message. The fourth RU 1207 may transmit a U-plane message including SRS data corresponding to the SRSs to the DU 1200. Although not shown in FIG. 12, the DU 1200 may generate channel information based on the results of SRS channel estimation performed by the DU 1200. The DU 1200 may transmit a C-plane message (e.g., C-plane message of Section type 6) including the generated channel information to the fourth RU 1207.

In embodiments, a method performed by a radio unit (RU) may include receiving sounding reference signals (SRS). The method may include receiving a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface. The method may include performing channel estimation based on the SRSs and the SRS configuration information. The method may include performing beamforming based on the channel estimation.

According to one embodiment, the SRS configuration information may include one or more parameters for generating the sequences of the SRSs. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the SRS configuration information may include UE identification information indicating a UE among one or more user equipment (UEs) that performs SRS transmission within an SRS symbol. The SRS configuration information may include frequency resource information indicated in PRB (physical resource block) units within the SRS symbol. The SRS configuration information may include one or more parameters for generating SRS sequences of the UE. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the section information of the C-plane message includes identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor for the first UE. factor) value. The section extension information of the C-plane message may include at least one of identification information of the second UE for multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE.

According to one embodiment, the method may include generating channel information based on the channel estimate. The method may include transmitting a C-plane message including the channel information to the DU through the fronthaul interface. The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. It may include at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset.

According to one embodiment, the method transmits a management plane (M-plane) message including capability information indicating that the channel estimation function using SRS is supported in the RU to the DU through the fronthaul interface. It may include actions such as:

In embodiments, a method performed by a distributed unit (DU) includes generating SRS configuration information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU). can do. The method may include transmitting a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface. The channel estimation may be used for beamforming in the RU.

According to one embodiment, the SRS configuration information may include one or more parameters for generating the sequences of the SRSs. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the SRS configuration information may include UE identification information indicating a UE among one or more user equipment (UEs) that performs SRS transmission within an SRS symbol. The SRS configuration information may include frequency resource information indicated in PRB (physical resource block) units within the SRS symbol. The SRS configuration information may include one or more parameters for generating SRS sequences of the UE. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the section information of the C-plane message includes identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor for the first UE. factor) value. The section extension information of the C-plane message may include at least one of identification information of the second UE for multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE.

According to one embodiment, the method may include transmitting a C-plane message including channel information calculated based on the channel estimate to the DU through the fronthaul interface. The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. It may include at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset.

According to one embodiment, the method receives a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU from the RU through the fronthaul interface. It may include actions such as:

In embodiments, an electronic device of a radio unit (RU) includes at least one fronthaul transceiver, at least one RF transceiver, and at least one coupled to the at least one fronthaul transceiver and the at least one RF transceiver. May include a processor. The at least one processor may be configured to receive sounding reference signals (SRS). The at least one processor may be configured to receive a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface. The at least one processor may be configured to perform channel estimation based on the SRSs and the SRS configuration information. The at least one processor may be configured to perform beamforming based on the channel estimation.

According to one embodiment, the SRS configuration information may include one or more parameters for generating the sequences of the SRSs. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the SRS configuration information may include UE identification information indicating a UE among one or more user equipment (UEs) that performs SRS transmission within an SRS symbol. The SRS configuration information may include frequency resource information indicated in PRB (physical resource block) units within the SRS symbol. The SRS configuration information may include one or more parameters for generating SRS sequences of the UE. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the section information of the C-plane message includes identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor for the first UE. factor) value. The section extension information of the C-plane message may include at least one of identification information of the second UE for multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE.

According to one embodiment, the at least one processor may be configured to generate channel information based on the channel estimate. The at least one processor may be configured to transmit a C-plane message including the channel information to the DU through the fronthaul interface. The channel information includes a channel information value of an in-phase sample, a channel information value of a quadrature sample, information indicating the range of reported physical resource blocks (PRBs), and a time offset. It may include at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset.

According to one embodiment, the at least one processor sends a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU, to the DU, and sends the fronthaul to the DU. It may be configured to transmit over an interface.

In embodiments, an electronic device of a distributed unit (DU) includes at least one transceiver. And it may include at least one processor coupled to the at least one transceiver. The at least one processor may be configured to generate SRS setting information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU). The at least one processor may be configured to transmit a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface. The channel estimation may be used for beamforming in the RU.

According to one embodiment, the SRS configuration information may include one or more parameters for generating the sequences of the SRSs. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the SRS configuration information may include UE identification information indicating a UE among one or more user equipment (UEs) that performs SRS transmission within an SRS symbol. The SRS configuration information may include frequency resource information indicated in units of physical resource blocks (PRB) within the SRS symbol. The SRS configuration information may include one or more parameters for generating SRS sequences of the UE. The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor.

According to one embodiment, the section information of the C-plane message includes identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor for the first UE. factor) value. The section extension information of the C-plane message may include at least one of identification information of the second UE for multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE.

According to one embodiment, the at least one processor may be configured to transmit a C-plane message including channel information calculated based on the channel estimate to the DU through the fronthaul interface. . The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. It may include at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset.

According to one embodiment, the at least one processor sends a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU, and sends a management plane (M-plane) message from the RU to the fronthaul. It may be configured to receive via an interface.

Methods according to 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.

When implemented as software, a computer-readable storage medium that stores one or more programs (software modules) may be provided. One or more programs stored in a computer-readable storage medium are configured to be executable by one or more processors in an electronic device (configured for execution). 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.

These programs (software modules, software) may include random access memory, non-volatile memory, including flash memory, read only memory (ROM), and electrically erasable programmable ROM. (electrically erasable programmable read only memory, EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other types of disk storage. It can be stored in an optical storage device or magnetic cassette. Alternatively, it may be stored in a memory consisting of a combination of some or all of these. Additionally, multiple configuration memories may be included.

In addition, the program may be distributed through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. It may be stored on an attachable storage device that is accessible. This storage device can be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communications network may be connected to the device performing embodiments of the present disclosure.

In the specific embodiments of the present disclosure described above, elements included in the disclosure are expressed in singular or plural numbers depending on the specific embodiment presented. However, 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, and even components expressed in plural may be composed of singular or singular. Even expressed components may be composed of plural elements.

Meanwhile, in the detailed description of the present disclosure, specific embodiments have been described, but of course, various modifications are possible without departing from the scope of the present disclosure.

Claims (20)

In the method performed by a radio unit (RU),
An operation of receiving sounding reference signals (SRS),
An operation of receiving a control plane (C-plane) message including SRS configuration information from a distributed unit (DU) through a fronthaul interface;
An operation of performing channel estimation based on the SRSs and the SRS configuration information;
Including the operation of performing beamforming based on the channel estimate,
method.
In claim 1,
The SRS configuration information includes UE identification information indicating a UE among one or more user equipment (UEs) performing SRS transmission within an SRS symbol,
The SRS configuration information includes frequency resource information indicated in PRB (physical resource block) units within the SRS symbol,
The SRS configuration information includes one or more parameters for generating SRS sequences of the UE,
The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor,
method.
In claims 1 to 2,
The section information of the C-plane message is at least one of identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor value for the first UE. Including,
The section extension information of the C-plane message includes at least one of identification information of the second UE for the multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE,
method.
In claims 1 to 3,
An operation of generating channel information based on the channel estimation;
Further comprising transmitting a C-plane message including the channel information to the DU through the fronthaul interface,
The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. Containing at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset,
method.
In claims 1 to 4,
Further comprising transmitting a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU to the DU through the fronthaul interface,
method.
In the method performed by a distributed unit (DU),
An operation of generating SRS setting information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU);
An operation of transmitting a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface,
The channel estimation is used for beamforming in the RU,
method.
In claim 6,
The SRS configuration information includes UE identification information indicating a UE among one or more user equipment (UEs) performing SRS transmission within an SRS symbol,
The SRS configuration information includes frequency resource information indicated in PRB (physical resource block) units within the SRS symbol,
The SRS configuration information includes one or more parameters for generating SRS sequences of the UE,
The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor,
method.
In claims 6 to 7,
The section information of the C-plane message is at least one of identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor value for the first UE. Including,
The section extension information of the C-plane message includes at least one of identification information of the second UE for the multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE,
method.
In claims 6 to 8,
Further comprising transmitting a C-plane message including channel information calculated based on the channel estimate to the DU through the fronthaul interface,
The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. Containing at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset,
method.
In claims 6 to 9,
Further comprising the operation of receiving a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU from the RU through the fronthaul interface,
method.
In the electronic device of the RU (radio unit),
at least one fronthaul transceiver;
at least one RF transceiver; and
At least one processor coupled to the at least one fronthaul transceiver and the at least one RF transceiver,
The at least one processor,
Receive sounding reference signals (SRS),
Receive a control plane (C-plane) message containing SRS configuration information from a distributed unit (DU) through the fronthaul interface,
Perform channel estimation based on the SRSs and the SRS configuration information,
Configured to perform beamforming based on the channel estimation,
Electronic devices.
In claim 11,
The SRS configuration information includes UE identification information indicating a UE among one or more user equipment (UEs) performing SRS transmission within an SRS symbol,
The SRS configuration information includes frequency resource information indicated in PRB (physical resource block) units within the SRS symbol,
The SRS configuration information includes one or more parameters for generating SRS sequences of the UE,
The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor,
Electronic devices.
In claims 11 to 12,
The section information of the C-plane message is at least one of identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor value for the first UE. Including,
The section extension information of the C-plane message includes at least one of identification information of the second UE for the multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE,
Electronic devices.
In claims 11 to 13, the at least one processor comprises:
Generate channel information based on the channel estimate,
It is additionally configured to transmit a C-plane message including the channel information to the DU through the fronthaul interface,
The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. Containing at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset,
Electronic devices.
In claims 11 to 14, the at least one processor comprises:
Additional configured to transmit a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU to the DU through the fronthaul interface,
Electronic devices.
In the electronic device of a distributed unit (DU),
at least one transceiver; and
Comprising at least one processor coupled to the at least one transceiver,
The at least one processor,
Generate SRS setting information for channel estimation using a sounding reference signal (SRS) in a radio unit (RU),
Configured to transmit a control plane (C-plane) message including the SRS configuration information to the RU through a fronthaul interface,
The channel estimation is used for beamforming in the RU,
Electronic devices.
In claim 16,
The SRS configuration information includes UE identification information indicating a UE among one or more user equipment (UEs) performing SRS transmission within an SRS symbol,
The SRS configuration information includes frequency resource information indicated in PRB (physical resource block) units within the SRS symbol,
The SRS configuration information includes one or more parameters for generating SRS sequences of the UE,
The one or more parameters include a sequence group number for a base sequence, a sequence number for the base sequence, a transmission comb type, a comb offset, and a cyclic shift. ), or at least one of a repetition factor,
Electronic devices.
In claims 16 to 17,
The section information of the C-plane message is at least one of identification information of the first user equipment (UE) for multiplexing, a cyclic shift value for the first UE, or a repetition factor value for the first UE. Including,
The section extension information of the C-plane message includes at least one of identification information of the second UE for the multiplexing, a cyclic shift value for the second UE, or a repetition factor value for the second UE,
Electronic devices.
In claims 16 to 18, the at least one processor comprises:
It is additionally configured to transmit a C-plane message including channel information calculated based on the channel estimate to the DU through the fronthaul interface,
The channel information includes channel information values of in-phase samples, channel information values of quadrature samples, information indicating the range of reported physical resource blocks (PRBs), and time offset. Containing at least one of information indicating, information indicating channel quality for the SRSs, or information indicating validity of the time offset,
Electronic devices.
In claims 16 to 19, the at least one processor comprises:
It is additionally configured to receive a management plane (M-plane) message including capability information indicating that a channel estimation function using SRS is supported in the RU from the RU through the fronthaul interface,
Electronic devices.

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