KR20230173549A - Electornic device and method for providing frequency offset in fronthaul interface - Google Patents

Abstract

According to embodiments, a method performed by a radio unit (RU) includes a control plane (C-plane) including frame structure information to indicate frequency offset information and subcarrier spacing (SCS). ) may include the operation of receiving a message from a distributed unit (DU). The method may include identifying a frequency offset factor among a plurality of frequency offset factors. The method may include obtaining a frequency offset value corresponding to a product of the frequency offset information, the SCS, and the frequency offset factor. The method may include transmitting a downlink signal based on the frequency offset value. The plurality of frequency offset factors may include '0.5' and '0.25'.

Description

Electronic device and method for providing frequency offset in fronthaul interface {ELECTORNIC DEVICE AND METHOD FOR PROVIDING FREQUENCY OFFSET IN FRONTHAUL INTERFACE}

This disclosure relates to a fronthaul interface. More specifically, the present disclosure relates to an electronic device and method for providing frequency offset 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.

This disclosure provides an electronic device and method for providing a frequency offset in more precise units.

Additionally, the present disclosure provides an apparatus and method for adaptively adjusting a frequency offset factor, which is a unit for expressing frequency offset on a fronthaul interface.

Additionally, the present disclosure provides an electronic device and method for compensating for raster-unit differences between an absolute radio frequency channel number (ARFCN) and a global synchronization channel number (GSCN) on a fronthaul interface.

Additionally, the present disclosure provides an apparatus and method for providing a frequency offset factor through a management plane (M-plane) message on a fronthaul interface.

Additionally, the present disclosure provides an apparatus and method for providing a frequency offset factor through a control plane (C-plane) message on a fronthaul interface.

According to embodiments, a method performed by a radio unit (RU) includes a control plane (C-plane) including frame structure information to indicate frequency offset information and subcarrier spacing (SCS). ) may include the operation of receiving a message from a distributed unit (DU). The method may include identifying a frequency offset factor among a plurality of frequency offset factors. The method may include obtaining a frequency offset value corresponding to a product of the frequency offset information, the SCS, and the frequency offset factor. The method may include transmitting a downlink signal based on the frequency offset value. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to embodiments, a method performed by a distributed unit (DU) may include determining frequency offset information related to a frequency offset factor from among a plurality of frequency offset factors. The method sends a control plane (C-plane) message containing section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a radio unit (RU). It may include an operation to transmit to. The frequency offset factor may be provided to the RU by a management plane (M-plane) message or the C-plane message. The frequency offset value applied to the downlink signal may correspond to the product of the frequency offset information, the SCS, and the frequency offset factor. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to 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 a control plane (C-plane) message including frequency offset information and information indicating subcarrier spacing (SCS) from a distributed unit (DU). there is. The at least one processor may be configured to identify a frequency offset factor among a plurality of frequency offset factors. The at least one processor may be configured to obtain a frequency offset value corresponding to a product of the frequency offset information, the SCS, and the frequency offset factor. The at least one processor may be configured to transmit a downlink signal based on the frequency offset value. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to 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 determine frequency offset information related to a frequency offset factor from among a plurality of frequency offset factors. The at least one processor sends a control plane (C-plane) message including section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a RU ( It may be configured to transmit to a radio unit). The frequency offset factor may be provided to the RU by a management plane (M-plane) message or the C-plane message. The frequency offset value applied to the downlink signal may correspond to the product of the frequency offset information, the SCS, and the frequency offset factor. The plurality of frequency offset factors may include '0.5' and '0.25'.

The electronic device and method according to embodiments of the present disclosure more accurately compensate for the frequency offset between channels with different numerology by adaptively adjusting the frequency offset factor on the fronthaul interface. can do.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

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.
FIG. 5A shows the difference in raster units between an absolute radio frequency channel number (ARFCN) and a global synchronization channel number (GSCN) according to embodiments.
Figure 6 shows an example of offset compensation of a synchronization signal block (SSB) having a center frequency different from the center frequency of the bandwidth, according to embodiments.
Figure 7 shows an example of a control plane (C-plane) message according to embodiments.
8 shows an example of section expansion information according to embodiments.
FIG. 9A shows an example of signaling between DU and RU to provide a frequency offset using a frequency offset factor through a management plane (M-plane) message and a C-plane message according to embodiments.
FIG. 9B shows an example of signaling between DU and RU to provide frequency offset using a frequency offset factor through a C-plane message, according to embodiments.
Figure 10 shows an example of signal processing of RU in mixed numerology channels, according to embodiments.

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 referring to merging used in the description below (e.g., merge, grouping, combination, aggregation, joint, integration, unifying) , terms referring to signals (e.g. packet, message, signal, information, signaling), terms referring to resources (e.g. section, symbol, slot, subframe, radio) Frame (radio frame), subcarrier (subcarrier), resource element (RE), resource block (RB), bandwidth part (BWP), opportunity), terms for computational states (e.g. step, operation) (operation, procedure), term referring to data (e.g. packet, message, user stream, information, bit, symbol, codeword), referring to channel Terms referring to network entities (distributed unit (DU), radio unit (RU), central unit (CU), control plane (CU-CP), user plane (CU-UP), O- Open radio access network (O-RAN) DU (DU), O-RAN RU (O-RU), O-RAN CU (O-CU), O-RAN CU-CP (O-CU-UP), O- CU-CP (O-RAN CU-CP)), terms referring to device components, etc. are provided as examples 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 operate in relatively high frequency bands (e.g., FR 2 (or FR 2-1 and FR 2-2) of NR, millimeter wave (mmWave) bands (e.g., 28 GHz, 30 GHz) , 38 GHz, 60 GHz) can transmit and receive wireless signals. 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 connection between entities between the wireless LAN and the base station, unlike 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 deployments such as C-RAN (centralized/cloud radio access network), DU performs functions for PDCP (packet data convergence protocol), RLC (radio link control), MAC (media access control), and PHY (physical). , the RU may be implemented to perform more 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, inverse fast fourier transform (iFFT) transformation (or fast fourier transform (FFT) transformation), It may include CP (cyclic prefix) insertion (CP removal) and digital beamforming. 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. 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 the 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 9B, 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 9B, 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 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 (management 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 can be implemented through hardware, 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. Also, 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 (management 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. It can perform mapping, channel estimation, layer demapping, demodulation, and decoding/descrambling. 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.

Hereinafter, in the present disclosure, unless otherwise specified, the embodiments include the third function separation 420a (which may be referred to as category A, CAT-A) or the fourth function separation 420a for performing beamforming processing in the RU. It is described based on functional separation 420b (which may be referred to as category B CAT-B). The O-RAN standard distinguishes between types of O-RUs 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.

Hereinafter, upper-PHY refers to physical layer processing processed in the DU of the fronthaul interface. For example, the upper-PHY may include FEC encoding/decoding, scrambling, and modulation/demodulation. Hereinafter, sub-PHY refers to physical layer processing processed in the RU of the fronthaul interface. For example, the sub-PHY may include FFT/iFFT, digital beamforming, physical random access channel (PRACH) extraction and filtering. However, the above-described criteria do not exclude embodiments with other functional separations. The functional configuration, signaling or operation of FIGS. 5A to 10 described later may be applied not only to the third functional separation 420a or fourth functional separation 420b but also to other functional separations.

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. other 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 stores the user's downlink data (IQ data or synchronization signal block (SSB)/reference signal (RS)), uplink data (IQ data or SRS/RS), or physical random access channel (PRACH) data. It can be included. 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

In 5G NR, a PRB containing the same number of subcarriers per PRB is defined for all numologies. PRB may include 12 subcarriers. Numerology refers to subcarrier spacing (SCS) and symbol length in an orthogonal frequency-division multiplexing (OFDM) system. Since the SCS may be different for each numerology, mixed numerologies may be used in the time domain and frequency domain, respectively. For example, for URLLC transmission, mixed numerologies may be used. Also, for example, in FR 2 (or FR 2-1, FR 2-2), if the numerology of data (e.g., physical downlink shared channel (PDSCH)) and the numerology of SSB (synchronization signal block) are different, Mixed numerologies can be used.

FIG. 5A shows the difference in raster units between an absolute radio frequency channel number (ARFCN) and a global synchronization channel number (GSCN) according to embodiments.

Referring to FIG. 5A, the frequency domain 500 may include candidates 510 for a bandwidth center frequency according to a channel raster. Each of the candidates for the bandwidth center frequency may be numbered based on ARFCN. The frequency domain 5300 may include candidates 520 of the SSB center frequency according to a synchronization raster. Each of the candidates for SSB center frequency may be numbered based on GSCN.

The global frequency raster defines F _REF , a set of RF reference frequencies. The RF reference frequency can be used to identify the location of RF channels, SSBs, and other elements in the signal. A global frequency raster is defined for all frequencies from 0 to 100 GHz. The granularity of the global frequency raster is ΔF _Global . The RF reference frequency may be specified based on NR-ARFCN (Absolute Radio Frequency Channel Number). For example, the relationship between N _REF corresponding to NR-ARFCN and F _REF corresponding to the RF reference frequency is as shown in the equation and table below.

Range of frequencies (MHz) Δ F _Global (kHz) F _REF-Offs (MHz) N _REF-Offs Range of N _REF 0 - 3000 5 0 0 0 - 599999 3000 - 24250 15 3000 600000 600000 - 2016666 24250 - 100000 60 24250.08 2016667 2016667 - 3279165

The synchronization raster may indicate the frequency positions of the SSB. Indicates the frequency location of the SSB that can be used by the UE for system acquisition when there is no explicit signaling of the synchronization block location. A global synchronization raster is defined for all frequencies. The frequency location of the SSB is defined as SS _REF with the corresponding number GSCN. For example, the positions of candidates 520 of synchronization signals (eg, SSB) according to the frequency range may be defined as in the table below.

Range of frequencies (MHz) SS block frequency position SS _REF GSCN Range of GSCN 0 - 3000 N * 1200　kHz + M * 50 kHz,N　=　1:2499, M {1,3,5} (Note) 3N + (M-3)/2 2 - 7498 3000 - 24250 3000 MHz + N * 1.44 MHz,
N = 0:14756 7499+N 7499 - 22255 24250 - 100000 24250.08 MHz + N * 17.28 MHz,
N = 0:4383 22256+N 22256 - 26639 NOTE: The default value for operating bands which only support SCS spaced channel raster(s) is M=3.

The SA (standalone) system is a system that operates the control plane (C-plane) and user plane (U-plane) on the same RAN node. The center frequency for transmitting SSB corresponding to the C-plane refers to SS _REF , but the center frequency of the system bandwidth (or BWP (bandwidth part)) corresponding to the user plane refers to F _REF . As described above, the difference is that SS _REF is a GSCN unit, while F _REF is ARFCN.

In the frequency band of FR 2, the unit of ARFCN is 60 kHz, while the unit of GSCN is 17.28 MHz, so if the center frequencies between the two channels are different, a frequency offset may occur between the two physical channels. For example, the frequency bands of FR 2 are n257 band (26.50 GHz to 29.50 GHz), n258 band (24.25 GHz to 27.50 GHz), n260 band (37.00 GHz to 40.00 GHz), or n261 band (27.25 GHz to 28.35 GHz). ) can be. SSB transmission in the frequency band of FR 2 can use numerology of 240 kHz. Meanwhile, the maximum SCS for data transmission in the frequency band of FR 2 is 120 kHz. However, the raster difference and SCS difference described above require frequency offset correction in finer units. The frequency compensation value can be expressed by the following equation.

here is the SCS of SSB, is SSB SS _REF , means F _REF , which is the center frequency of the channel bandwidth. For example, in the n257 band, the frequency offset for each GSCN according to the search for SSB with an SCS of 240 kHz can be expressed as follows.

n257 GSCN offset 22256 GSCN start 22390 GSCN step 2 SS _REF offset (kHz) 24250080 SS _REF step (kHz) 17280 GSCN N SS _REF (kHz) 22390 134 26565600 0 22392 136 26600160 0.75 22394 138 26634720 0.5 22396 140 26669280 0.25 22398 142 26703840 0 22400 144 26738400 0.75 22402 146 26772960 0.5 22404 148 26807520 0.25 22406 150 26842080 0

FIG. 6 shows an example of offset compensation of a synchronization signal block (SSB) having a center frequency different from the center frequency of the system bandwidth, according to embodiments.

Referring to FIG. 6, a model is assumed where the center frequency of the system bandwidth 653 (hereinafter referred to as bandwidth center frequency 651) and the center frequency of SSB (hereinafter referred to as SSB center frequency 655) are different. The bandwidth center frequency 651 is f ₀ and the SSB center frequency 655 is f _ssb . The difference 657 between the two center frequencies is f _d (frequency discrepancy) (=f _ssb -f ₀ ).

f _d is the SCS of SSB ( ), it can include multiple parts and fractional parts. The multiple part means the part that is an integer multiple of the SCS of the SSB in the center frequency difference. The fractional part may be the portion of the SCS of the SSB at the center frequency difference. That is, the fractional part may be the product of the SCS of SSB and a fraction less than 0 and less than 1 (or a fraction whose magnitude is less than 1). The drainage part is It is expressed as, and the fractional part is ( , or ) can be expressed as Is It can be defined as an RE (resource element) offset with a unit. According to the 3GPP standard (e.g., Section 5.4 of 3GPP TS 38.211), since the bandwidth center frequency 651 is used in upconversion of SSB, the time domain of SSB can be developed as the following equation.

here, means the SSB signal converted from the frequency domain to the time domain. represents the CP (cyclic prefix) length of the l-th symbol. represents the size of IFFT (Inverse Fast Fourier Transform). represents the sampling rate (unit second). is RE offset It means an SSB signal in the time domain that has been frequency-shifted by that amount. in other words, am.

Referring to Equation 5, the components of system bandwidth ( ) and frequency transition component ( ), the center frequency of the system bandwidth ( ) based on the correction value ( ) the frequency is shifted. Frequency shift components identified from the frequency offset ( ) can also be corrected in the time domain. When O-RAN functional separation (e.g., third functional separation 420a or fourth functional separation 420b), correction in the time domain can be performed in the RU.

For correction in RU, the O-RAN standard provides a freqOffset field in section type '3' and section extension type '15'. DU can provide the frequency offset value to the RU through a C-plane message. Here, the field of freqOffset can be defined as follows.

Here, 'Δf' refers to the SCS provided in the frame structure. 'freqOffset' is the value of the freqOffset field of the C-plane message. The value of the freqOffset field of the C-plane message expresses the frequency offset value as the number of counting units by considering a part of the SCS as a counting unit. Hereinafter, the ratio indicating a portion of the SCS may be referred to as a frequency offset factor (or fractional frequency offset). As an example, in Equation 6, the frequency offset factor is 0.5. The product of the frequency offset factor and SCS may be referred to as an offset unit. For example, for an SSB with a SCS of 240 kHz, the DU may inform the RU of an offset unit of 120 kHz. However, since ARFCN is in units of 60 kHz, it is difficult for an offset unit of 120 kHz to indicate sufficient frequency offset. For example, examining Table 3, due to the separation of GSCN and ARFCN and the difference in resolution between SS _REF and F _REF , The size of is formed in units of 0.25.

In FR 2 (or FR 2-1), the channel raster of ARFCN is 60 kHz, but the numerology of SCS is 240 kHz, so frequency compensation in units of 60/240=(1/4) is required. In addition, considering the FR 2-2 frequency band introduced in Release 17, in the frequency bands supporting SCS of 480 kHz and SCS of 960 kHz, frequency compensation is offset in units finer than '0.5' in Equation 6 (e.g. : 0.25, 0.125) is required.

In embodiments of the present disclosure, a method for providing all possible frequency compensation values to the RU through the O-RAN standard is proposed by analyzing the occurrence range of the frequency compensation value. In particular, in an FR2 stand-alone (SA) system, when the center frequency between the SSB and the system bandwidth is different, frequency offset compensation that requires support in more detailed units is explained as an example situation.

Figure 7 shows an example 700 of a control plane (C-plane) message according to embodiments. In Figure 7, 'sectionType=3' for mixed numerology channels is illustrated. However, the section type indicating '3' is only an example, and other section types may be used to provide a frequency offset (e.g., 'freqOffset' of the ORAN standard).

Referring to FIG. 7, the C-plane message 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.

C-plane messages 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 to indicate the location of a time resource to which the message 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. Common header information may include 'sectionType' that determines the characteristics of U-plane data. Common header information may include 'timeoffset', which defines the offset from the start of the slot to the start of the CP (cyclic prefix) as the number of samples (e.g., T _s = 1/30.72 MHz (megahertz)). Common header information may include 'frameStructure' that defines fast fourier transfer (FFT)/inverse FFT (iFFT) size and SCS. Common header information may include 'cpLength', which defines the CP length as the number of samples (e.g., T _s = 1/30.72 MHz (megahertz)).

'frameStructure', included in the common header information, defines the frame structure. 'frameStructure' can indicate FFT/iFFT size and SCS. For example, for frame structure, the table below may be referred to.

0(msb) One 2 3 4 5 6 7(lsb) Number of Octects FFT Size μ (Subcarrier spacing) One Oct 1

The first part of 'frameStructure' (e.g., most significant bit (MSB) 4-bit) may indicate the 'FFT Size' parameter. The 'FFT Size' parameter defines the FFT/iFFT size used for processing all IQ data related to C-plane messages. The second part of 'frameStructure' (e.g. LSB (least significant bit) 4-bit) may indicate the 'μ' parameter. The 'μ' parameter defines the number of slots and SCS per 1 ms (milliseconds) subframe, considering LTE specifications (e.g. TS 36.211) and NR specifications (e.g. TS 38.211). Meanwhile, the provided “FFT Size” parameter is intended to facilitate calculation and is not intended to strictly dictate the time-frequency conversion method of the RU.

For the 'FFT Size' parameter, the table below may be referred to.

Value of IE "FFT_size" FFT/iFFT size 0000b Reserved (no FFT/iFFT processing) 0001b...0110b Reserved 0111b 128 1000b 256 1001b 512 1010b 1024 1011b 2048 1100b 4096 1101b 1536 1110, 1111b Reserved

For the 'μ' parameter, the table below may be referred to.

Value of IE "SCS" 3GPP "μ" Subcarrier spacing Δf Number of slots per 1ms sub-
frame: N _slot Slot length 0000b 0 15 kHz One 1ms 0001b One 30 kHz 2 500μs 0010b 2 60kHz 4 250μs 0011b 3 120kHz 8 125μs 0100b 4 240 kHz 16 62.5μs 0101b...1011b N.A. Reserved Reserved Reserved 1100b N.A. 1.25 kHz One 1ms 1101b N.A. 3.75 kHz (LTE-specific) One 1ms 1110b N.A. 5 kHz One 1ms 1111b N.A. 7.5 kHz (LTE-specific) One 1ms

1.25 kHz, 5 kHz can be supported for NR PRACH. 3.75 kHz can be supported for PRACH of narrowband (Nb)-internet of everything (IoT). 15 kHz, 7.5 kHz, and 1.25 kHz can be supported for LTE PRACH. 1.25 kHz, 7.5 kHz can be supported for LTE PRACH.

C-plane messages may include section information. Section information 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. The purpose of 'sectionId' is to map a U-Plane data section to the corresponding C-Plane message (and section type) associated with the data. Section information is 'rb' indicating whether all RBs are used (every RB is used) or every other RB (every other RB) is used, 'symInc' indicating a symbol number increment command, and data 'startPrbc' to indicate the start PRB number of the data section description, 'numPrbc' to indicate the number of consecutive PRBs for each data section description, 'reMask' to define the RE mask in the PRB, 'numSymbol' defines the number of PRACH (physical random access channel) repetitions or number of symbols to which section control is applied, 'ef' to indicate the extension flag, and the beam pattern to be applied to the U-plane data. It can contain the defining 'beamId'. The section information may include frequency offset information, that is, 'freqOffset', which defines the frequency offset with respect to the carrier center frequency in a specific unit (hereinafter referred to as offset unit). The offset unit corresponds to the product of SCS and a fractional value. Here, the fractional value may be referred to as a frequency offset factor. The frequency span due to 'frameStructure', 'freqOffset', 'startPrbc', 'numPrbc' and 'rb' in the C-plane message does not exceed the channel bandwidth configured for eAxC in the M-plane.

The value indicated by the bits of the frequency offset information, in units of offset, defines the frequency offset with respect to the carrier center frequency before additional filtering (e.g., in the case of PRACH) and FFT processing (in the case of UL). The frequency offset must be consistent from data section to data section (a section cannot use reMask to allow different frequency offsets for different REs of PRBs).

In some embodiments, frequency offset information included in the C-plane message may be used to identify a frequency offset value based on the M-plane message. The M-plane message may indicate a frequency offset factor. The M-plane message may include information indicating the frequency offset factor. For example, the frequency offset factor provided by the M-plane message may be 0.5. Additionally, for example, the frequency offset factor provided by the M-plane message may be 0.25. Additionally, for example, the frequency offset factor provided by the M-plane message may be 0.125.

According to one embodiment, the frequency offset value may be determined based on the following equation.

'frequency_offset' indicates the frequency offset value to be applied. Δf represents the SCS provided by the frame structure information of the C-plane message. 'freqOffset' means the value of the bits of frequency offset information received from the C-plane message. 'fractFreqMode' represents information indicating the frequency offset factor included in the M-plane message. Here, the DU can transmit information indicating the frequency offset factor to the RU through the optional multi-vendor functionality of the O-RAN standard in the M-plane. For example, 'fractFreqMode' information can be added as an 'optional multi-vendor' item.

As an example, frequency offset information may consist of 24 bits. The 24 bits represent a signed integer. If the 24 bits indicate 0, it indicates that there is no offset, and if the value of the 24 bits is in the range from 0x000001 to 0x7FFFFF (0x represents a hexadecimal number, F is 15), the frequency offset information is a positive frequency offset. , and if the value of the 24 bits is in the range from 0x800000 to 0xFFFFFF, the frequency offset information may indicate a negative frequency offset.

In some other embodiments, the frequency offset information included in the C-plane message may be used to identify the frequency offset value based on frame structure information included in the C-plane message. Frame structure information included in the C-plane message may include FFT information to indicate the FFT/iFFT size used for IQ data processing and numerology information to indicate the SCS. As described above, Table 4 can be used for frame structure information. Table 5 can be used for FFT information. However, unlike Table 6, the numerology information may indicate not only the SCS but also the frequency offset factor. For example, the table below can be used for numerology information according to embodiments.

Value of IE "SCS" 3GPP "μ" Subcarrier spacing Δf Number of slots per 1ms sub-
frame: N _slot Slot length 0000b 0 15 kHz One 1ms 0001b One 30 kHz 2 500μs 0010b 2 60kHz 4 250μs 0011b 3 120kHz 8 125μs 0100b 4 240 kHz 16 62.5μs 0101b 5 480 kHz 32 31.25μs 0110b 6 960 kHz 64 15.625μs 0111b 2 60 kHz 4 250μs 1000b 3 120kHz 8 125μs 1001b 4 240 kHz 16 62.5μs 1010b 5 480 kHz 32 31.25μs 1011b 6 960 kHz 64 15.625μs 1100b N.A. 1.25 kHz One 1ms 1101b N.A. 3.75 kHz (LTE-specific) One 1ms 1110b N.A. 5 kHz One 1ms 1111b N.A. 7.5 kHz (LTE-specific) One 1ms

If the value of the bits of the numerology information is 2, the SCS may be 60 kHz and the frequency factor may be 0.5. However, if the value of the bits of the numerology information is 7 (=0111b), the SCS may be 60 kHz and the frequency factor may be 0.25. Also, for example, if the value of the bits of the numerology information is 3, the SCS may be 120 kHz and the frequency factor may be 0.5. However, if the value of the bits of the numerology information is 8 (=1000b), the SCS may be 120 kHz and the frequency factor may be 0.25. Also, for example, if the value of the bits of the numerology information is 4, the SCS may be 240 kHz and the frequency factor may be 0.5. However, if the value of the bits of the numerology information is 9 (=1001b), the SCS may be 240 kHz and the frequency factor may be 0.25. Also, for example, if the value of the bits of the numerology information is 5, the SCS may be 480 kHz and the frequency factor may be 0.5. However, if the value of the bits of the numerology information is 10 (=1010b), the SCS may be 480 kHz and the frequency factor may be 0.25. Also, for example, if the value of the bits of the numerology information is 6, the SCS may be 960 kHz and the frequency factor may be 0.5. However, if the value of the bits of the numerology information is 11 (=1011b), the SCS may be 960 kHz and the frequency factor may be 0.25. The values of the bits of numerology information may indicate frequency facts. Table 7 can be expressed by the following equation.

'frameStructure[4:7]' refers to the LSB 4-bit of frame structure information and refers to bits to indicate the SCS. 'frequency_offset' indicates the frequency offset value to be applied. Δf represents the SCS provided by the frame structure information of the C-plane message. 'freqOffset' means the value of the bits of frequency offset information received from the C-plane message.

As an example, frequency offset information may consist of 24 bits. The 24 bits represent a signed integer. If the 24 bits indicate 0, it indicates no offset, if the value of the 24 bits is in the range from 0x000001 to 0x7FFFFF, the frequency offset information indicates a positive frequency offset, and if the value of the 24 bits is in the range from 0x800000 to 0xFFFFFF, the frequency offset information indicates a positive frequency offset. , the frequency offset information may indicate a negative frequency offset.

Table 7 is only an example of frame structure information for defining additional offset factors and is not to be interpreted as limiting the embodiments. As shown in Table 7, not all reserved bits in Table 4 are used to indicate additional SCSs (480 kHz, 960 kHz) and the frequency offset factor, but only some of the reserved bits in Table 4 are used to indicate the frequency offset factor. It may also be used for For example, the values of the bits to indicate SCS provide various frequency offset factors (e.g., 0.5, 0.25), only for situations where additional frequency offset factors are needed (e.g., 240 kHz, 480 kHz, 960 kHz). can do.

Value of IE "SCS" 3GPP "μ" Subcarrier spacing Δf Number of slots per 1ms sub-
frame: N _slot Slot length 0000b 0 15 kHz One 1ms 0001b One 30 kHz 2 500μs 0010b 2 60 kHz 4 250μs 0011b 3 120kHz 8 125μs 0100b 4 240 kHz 16 62.5μs 0101b 5 480 kHz 32 31.25μs 0110b 6 960 kHz 64 15.625μs 0111b 4 240 kHz 16 62.5μs 1000b 5 480 kHz 32 31.25μs 1001b 6 960 kHz 64 15.625μs 1010b-1011b N.A. Reserved Reserved Reserved 1100b N.A. 1.25 kHz One 1ms 1101b N.A. 3.75 kHz (LTE-specific) One 1ms 1110b N.A. 5 kHz One 1ms 1111b N.A. 7.5 kHz (LTE-specific) One 1ms

As another example, the values of the bits to indicate SCS can be set to various frequency offset factors (e.g., 0.5, 0.25, 0.125), only for situations where additional frequency offset factors are needed (e.g., 240 kHz, 480 kHz, 960 kHz). ) can be provided.

Value of IE "SCS" 3GPP "μ" Subcarrier spacing Δf Number of slots per 1ms sub-
frame: N _slot Slot length 0000b 0 15 kHz One 1ms 0001b One 30 kHz 2 500μs 0010b 2 60 kHz 4 250μs 0011b 3 120kHz 8 125μs 0100b 4 240 kHz 16 62.5μs 0101b 5 480 kHz 32 31.25μs 0110b 6 960 kHz 64 15.625μs 0111b 4 240 kHz 16 62.5μs 1000b 5 480 kHz 32 31.25μs 1001b 6 960 kHz 64 15.625μs 1010b 4 240 kHz 16 62.5μs 1011b 5 480 kHz 32 31.25μs 1100b N.A. 1.25 kHz One 1ms 1101b N.A. 3.75 kHz (LTE-specific) One 1ms 1110b N.A. 5 kHz One 1ms 1111b N.A. 7.5 kHz (LTE-specific) One 1ms

If the SCS bits indicate 10, the SCS is 240 kHz, and the frequency offset factor may be 0.125. If the SCS bits point to 11, the SCS is 480 kHz, and the frequency offset factor may be 0.125.

In Tables 7 to 9 described above, the range of field values of bits for indicating SCC (e.g., frameStructure[4:7] in Equation 8) indicates the frequency offset factor. In Tables 7 to 9, regardless of the value of SCS, the field value indicates the frequency offset factor. However, the range of possible frequency offset factors may be SCS dependent. In other words, depending on which SCS is used, candidate values of the required frequency offset factor may vary. For example, if the SCS is 120 kHz, only a frequency offset factor of 0.5 can be used. For another example, if the SCS is 480 kHz, frequency offset factors with values of 0.5, 0.25, and 0.125 may be used. As an example, the field value may indicate SCS and frequency offset factor according to the table below and the equation below.

Value of IE "SCS" 3GPP "μ" Subcarrier spacing Δf Number of slots per 1ms sub-
frame: N _slot Slot length 0000b 0 15 kHz One 1ms 0001b One 30 kHz 2 500μs 0010b 2 60kHz 4 250μs 0011b 3 120kHz 8 125μs 0100b 4 240 kHz 16 62.5μs 0101b 5 480 kHz 32 31.25μs 0110b 6 960 kHz 64 15.625μs 1001b 4 240 kHz 16 62.5μs 1010b 5 480 kHz 32 31.25μs 1011b 6 960 kHz 64 15.625μs 1010b 5 480 kHz 32 31.25μs 1011b 6 960 kHz 64 15.625μs 1100b N.A. 1.25 kHz One 1ms 1101b N.A. 3.75 kHz (LTE-specific) One 1ms 1110b N.A. 5 kHz One 1ms 1111b N.A. 7.5 kHz (LTE-specific) One 1ms

According to an additional embodiment, the frequency offset factor indicated by the field value of the bits for indicating the SCS may be associated with the SCS provided by the field value. Depending on the SCS provided, the frequency offset factor(s) used may be fixed. For example, if the field values of the bits for indicating the SCS indicate an SCS of 240 kHz, the frequency offset may be 0.5 or 0.25. For another example, if the field values of the bits for indicating the SCS indicate an SCS of 480 kHz, the frequency offset may be 0.25 or 0.125. For another example, if the field values of the bits for indicating the SCS indicate an SCS of 960 kHz, the frequency offset may be 0.125 or 0.0625.

Within the equivalent technical scope, some elements may be omitted from Tables 7 to 10, or other mapping columns may be added.

In FIG. 7, the frequency offset information included in the section information of the C-plane message is described as an example, but the frequency offset information may be included in not only the section information but also the section extension information. Hereinafter, in FIG. 8, section expansion information including frequency offset information is described.

8 shows an example 800 of section expansion information according to embodiments. In Figure 8, section expansion information for mixed-numerology information is illustrated. C-plane messages may include section information and section extension information. Here, the section type of section information may be '5' or '6'. The C-plane message may be used for UE scheduling information (sectionType=5) or may be used for transmission of UE-specific channel information (sectionType=6).

Referring to FIG. 8, section extension information may include 'extType', which provides an extension type that provides additional parameters. 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.

Section extension information may include 'frameStructure' (e.g., frame structure information in FIG. 7) to indicate the frame structure. 'frameStructure' defines the FFT/iFFT size and SCS. Section extension information may include 'cpLength'. 'cpLength' is the number of samples (e.g. T _s = 1/30.72 MHz (megahertz)) and defines the CP length. Section extension information may include 'freqOffset'. 'freqOffset' according to embodiments defines the frequency offset with respect to the carrier center frequency before additional filtering (eg, in the case of PRACH) and FFT processing (in the case of UL), in units of frequency offset factor. Meanwhile, when section expansion information is applied to section type 6 ('sectionType=6'), the value of 'FFT Size' in frameStructure and cpLength can be set to '0'.

According to embodiments, the frequency offset information indicated by the section expansion information indicates a frequency offset value based on the methods mentioned in FIG. 7 (e.g., Equation 7 to Equation 9, Tables 7 to Table 10) can do. The frequency offset value corresponds to the product of the frequency offset information indicated by the section extension information, the SCS value of the frame structure information indicated by the section extension information, and the frequency offset factor. According to one embodiment, the frequency offset factor may be set based on the M-plane message. For example, in the M-plane message, 'fractFreqMode' information, which is an 'optional multi-vendor' item, may indicate a frequency offset factor. According to one embodiment, the frequency offset factor may be set based on the C-plane message. For example, 4-bit LSB of the frame structure information of a C-plane message may indicate a frequency offset factor.

FIG. 9A shows an example of signaling between DU and RU to provide a frequency offset using a frequency offset factor through a management plane (M-plane) message and a C-plane message 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.

Referring to FIG. 9A, in operation S901, the DU 210 may determine the frequency offset factor. The frequency offset factor will be used to determine the offset unit to indicate the frequency location of the lowest resource element (RE) (RE #0) of the lowest resource block (RB) (RB #0) from the center frequency. You can. The offset unit can be determined as the product of the frequency offset factor and SCS. According to one embodiment, the frequency offset factor may be 0.5. According to one embodiment, the frequency offset factor may be 0.25. According to one embodiment, the frequency offset factor may be 0.125.

The frequency offset value indicates the actual frequency distance from the center frequency to RE #0 of the assigned RB #0. However, since the center frequency is determined in ARFCN units, while RE is determined in SCS units, the SCS units may not be sufficient to accurately display the frequency offset value. Therefore, the DU 210 according to embodiments provides the frequency offset factor to the RU 220 through mode information. The frequency offset factor refers to a fractional value applied to the SCS to indicate the frequency offset value.

In operation S903, the DU 210 may transmit a management plane (M-plane) message to the RU 220. The M-plane message may include mode information. Mode information may indicate a frequency offset factor. According to one embodiment, through the optional multi-vendor functionality of the M-plane of the O-RAN standard, the M-plane message may indicate a frequency offset factor. For example, 'fractFreqMode' information can be added as an 'optional multi-vendor' item. For example, when 'fractFreqMode' information is 0, the frequency offset factor is 0.5. When the 'fractFreqMode' information is 1, the frequency offset factor is 0.25. When the 'fractFreqMode' information is 2, the frequency offset factor is 0.125. Values of 3, 4, 5, 6, or 7 in the 'fractFreqMode' information may be reserved for future use.

In operation S905, the DU 210 may transmit a control plane (C-plane) message to the RU 220. The C-plane message may include frequency offset information and numerology information. C-plane messages may include frequency offset information. Frequency offset information may indicate a frequency range from the carrier center frequency to the lowest resource element (RE) of the lowest resource block (RB), in units of offset. Here, the offset unit corresponds to the product of the frequency offset factor determined in operation S901 and the SCS provided by the numerology information of the C-plane message. C-plane messages may include numerology information. Numerology information refers to bits for indicating the SCS among the bits of the frame structure information of the C-plane message. The values of bits to indicate SCS can be indicated by referring to Tables 6 to 10.

In operation S907, RU 220 may obtain a frequency offset value. The frequency offset value is the product of the SCS provided by the C-plane message, the frequency offset factor provided by the mode information of the M-plane message, and the frequency offset information provided by the C-plane message.

In operation S909, the RU 220 may transmit a downlink signal. RU 220 may generate OFDM signals. The RU 220 can generate a downlink signal through modulation and up-conversion at the center frequency of the OFDM signal. The RU 220 may transmit a downlink signal to user equipment (UE) within the cell. The RU 220 may transmit a downlink signal based on the frequency offset value. According to one embodiment, the downlink signal may include a synchronization signal. For example, the frequency band in which the downlink signal is transmitted may be FR 2 (or FR 2-1 or FR 2-2). The SCS of the sync signal may be 240 kHz, 480 kHz, or 960 kHz.

FIG. 9B shows an example of signaling between DU and RU to provide frequency offset using a frequency offset factor through a C-plane message, 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.

Referring to FIG. 9B, in operation S951, the DU 210 may transmit a control plane (C-plane) message to the RU 220. The C-plane message may include frequency offset information and numerology information. C-plane messages may include frequency offset information. Frequency offset information, in offset units, refers to the frequency range from the carrier center frequency to the lowest resource element (RE) (RE #0) of the lowest resource block (RB) (RB #0). You can. Here, the offset unit corresponds to the product of the frequency offset factor determined in operation S901 and the SCS provided by the numerology information of the C-plane message. C-plane messages may include numerology information. Numerology information refers to bits for indicating the SCS among the bits of the frame structure information of the C-plane message. The values of bits to indicate SCS can be indicated by referring to Tables 7 to 10.

In operation S953, the RU 220 may identify the value of the numerology information. Numerology information of the C-plane message according to embodiments may indicate a frequency offset factor. The frequency offset factor may be used to determine the offset unit to indicate the frequency location of the lowest resource element (RE) of the lowest resource block (RB) from the center frequency. The offset unit is the product of the frequency offset factor and SCS. According to one embodiment, the frequency offset factor may be 0.5. According to one embodiment, the frequency offset factor may be 0.25. According to one embodiment, the frequency offset factor may be 0.125.

The frequency offset value indicates the actual frequency distance from the center frequency to RE #0 of the assigned RB #0. However, since the center frequency is determined in ARFCN units, while RE is determined in SCS units, the SCS units may not be sufficient to accurately display the frequency offset value. Therefore, the DU 210 according to embodiments provides the frequency offset factor to the RU 220 through the numerology information of the C-plane message. The frequency offset factor refers to a fractional value applied to the SCS to indicate the frequency offset value.

In operation S955, RU 220 may identify the offset determination method. The offset determination method may depend on the offset factor. The offset determination method specifies the frequency offset factor. The RU 220 may identify the frequency offset factor based on the values of the bits of the numerology information. According to embodiments, the values of the bits of the numerology information may indicate not only the SCS but also the frequency offset factor. Based on the range to which the values of the bits of the numerology information belong, the RU 220 may identify the frequency offset factor. For example, RU 220 may identify an offset determination method according to Equation 7. Additionally, for example, RU 220 may identify an offset determination method according to Equation 8. Additionally, for example, RU 220 may identify an offset determination method according to Equation 9.

In operation S957, RU 220 may obtain a frequency offset value. The frequency offset value is the product of the SCS provided by the C-plane message, the frequency offset factor provided by the mode information of the M-plane message, and the frequency offset information provided by the C-plane message. The RU 220 may obtain a frequency offset value based on the offset determination method in operation S955. The RU 220 may obtain a frequency offset value based on the frequency offset factor identified in operation S955.

In operation S959, the DU 210 may transmit a downlink signal to the RU 220. RU 220 may generate OFDM signals. The RU 220 can generate a downlink signal through modulation and up-conversion at the center frequency of the OFDM signal. The RU 220 may transmit a downlink signal to user equipment (UE) within the cell. The RU 220 may transmit a downlink signal based on the frequency offset value. According to one embodiment, the downlink signal may include a synchronization signal. For example, the frequency band in which the downlink signal is transmitted may be FR 2 (or FR 2-1 or FR 2-2). The SCS of the sync signal may be 240 kHz, 480 kHz, or 960 kHz.

7 to 9B illustrate an embodiment of providing a frequency offset through a C-plane message, but embodiments of the present disclosure are not limited thereto. According to another embodiment, the frequency offset factor may be indicated only with an M-plane message. The frequency offset factor set by default by the M-plane message may be 0.5, 0.25, or 0.125. The frequency offset factor set by default by the M-plane message may depend on the center of the SCS or channel bandwidth that is set by default.

10 shows an example 1000 of signal processing of a RU in mixed numerology channels, according to embodiments. RU illustrates RU 220 in FIG. 2A. According to one embodiment, RU 220 may include O-RU 253.

Referring to FIG. 10, the RU can perform IFFT and CP addition to the data signal 1011. RU can perform filtering. The RU may perform IFFT and CP addition to the synchronization signal 1013 (e.g., SSB). The RU may perform compensation 1030 for frequency shift components before performing filtering.

The unit for searching the center frequency of the data signal 1011 is 60 kHz at FR 2. The unit for searching the synchronization signal 1013 is 17280 kHz at FR 2. According to the 3GPP standard, upconversion of the synchronization signal 1013 is performed based on the carrier center frequency, which is identified in units of 60 kHz. Accordingly, in the distance between the center frequency of the synchronization signal 1013 and the center frequency of the data signal 1011, a remaining portion may exist in addition to a portion distinguished by a multiple of SCS. This remaining portion is subject to compensation.

As explained through Equation 3 to Equation 5, the compensation target ( ) corresponds to the time-frequency transformation. Accordingly, compensation 1030 may be performed in the RU. As shown in Equation 5, the components of the system bandwidth ( ) and frequency transition component ( ), the center frequency of the system bandwidth ( ) based on the correction value ( ) the frequency can be shifted as much as.

The RU can receive frequency offset information from the DU through the fronthaul interface of the O-RAN. The RU can identify the frequency offset value based on the frequency offset information. Based on the frequency offset value, RU calculates compensation components (e.g. frequency shift components ( )) can be determined. The RU may perform compensation 1030 of the synchronization signal 1013 based on the compensation component. For example, RU is a sample unit of time, ' By multiplying ', compensation 1030 of the synchronization signal 1013 can be performed. The RU may perform filtering after compensating for the synchronization signal 1013.

The RU may perform up-conversion (1050) on a composite signal including a filtered data signal and a filtered synchronization signal. Upconversion 1050 may be performed based on the carrier frequency (or carrier center frequency). For example, RU adds ' By multiplying ', up-conversion (1050) of the composite signal can be performed. The RU may perform upconversion (1050) and then output a downlink signal.

According to embodiments of the present disclosure, the RU can obtain an accurate frequency offset by using the frequency offset factor of the message received from the DU instead of using a fixed frequency offset factor.

According to embodiments, a method performed by a radio unit (RU) includes a control plane (C-plane) including frame structure information to indicate frequency offset information and subcarrier spacing (SCS). ) may include an operation of receiving a message from a distributed unit (DU). The method may include identifying a frequency offset factor among a plurality of frequency offset factors. The method may include obtaining a frequency offset value corresponding to a product of the frequency offset information, the SCS, and the frequency offset factor. The method may include transmitting a downlink signal based on the frequency offset value. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to one embodiment, the method may further include receiving a management plane (M-plane) message from the DU including mode information for indicating the frequency offset factor.

According to one embodiment, the frame structure information may include bits to indicate the SCS. If the values of the bits fall within the first range, the identified frequency offset factor may be '0.5'. If the values of the bits belong to a second range that is different from the first range, the identified frequency offset factor may be '0.5'.

According to one embodiment, the plurality of frequency offset factors may further include '0.125' and '0.0625'.

According to one embodiment, the section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is the C-plane message. It can be included in the section information of the plane message. Alternatively, the section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for UE channel information transmission, and the frame structure information is included in the section extension information of the C-plane message. may be included.

According to embodiments, a method performed by a distributed unit (DU) may include determining frequency offset information related to a frequency offset factor from among a plurality of frequency offset factors. The method sends a control plane (C-plane) message containing section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a radio unit (RU). It may include an operation to transmit to. The frequency offset factor may be provided to the RU by a management plane (M-plane) message or the C-plane message. The frequency offset value applied to the downlink signal may correspond to the product of the frequency offset information, the SCS, and the frequency offset factor. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to one embodiment, the method may further include transmitting the M-plane message to the RU. The M-plane message may include mode information indicating the frequency offset factor.

According to one embodiment, the frame structure information may include bits to indicate the SCS. If the values of the bits fall within the first range, the identified frequency offset factor may be '0.5'. If the values of the bits belong to a second range that is different from the first range, the identified frequency offset factor may be '0.5'.

According to one embodiment, the plurality of frequency offset factors may further include '0.125' and '0.0625'.

According to one embodiment, the section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is the C-plane message. It can be included in the section information of the plane message. Alternatively, the section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for UE channel information transmission, and the frame structure information is included in the section extension information of the C-plane message. may be included.

According to 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 a control plane (C-plane) message including frequency offset information and information indicating subcarrier spacing (SCS) from a distributed unit (DU). there is. The at least one processor may be configured to identify a frequency offset factor among a plurality of frequency offset factors. The at least one processor may be configured to obtain a frequency offset value corresponding to a product of the frequency offset information, the SCS, and the frequency offset factor. The at least one processor may be configured to transmit a downlink signal based on the frequency offset value. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to one embodiment, the at least one processor may be additionally configured to receive a management plane (M-plane) message from the DU including mode information for indicating the frequency offset factor.

According to one embodiment, the frame structure information may include bits to indicate the SCS. If the values of the bits fall within the first range, the identified frequency offset factor may be '0.5'. If the values of the bits belong to a second range that is different from the first range, the identified frequency offset factor may be '0.5'.

According to one embodiment, the plurality of frequency offset factors may further include '0.125' and '0.0625'.

According to one embodiment, the section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is the C-plane message. It can be included in the section information of the plane message. Alternatively, the section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for UE channel information transmission, and the frame structure information is included in the section extension information of the C-plane message. may be included.

According to 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 determine frequency offset information related to a frequency offset factor from among a plurality of frequency offset factors. The at least one processor sends a control plane (C-plane) message including section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a RU ( It may be configured to transmit to a radio unit). The frequency offset factor may be provided to the RU by a management plane (M-plane) message or the C-plane message. The frequency offset value applied to the downlink signal may correspond to the product of the frequency offset information, the SCS, and the frequency offset factor. The plurality of frequency offset factors may include '0.5' and '0.25'.

According to one embodiment, the at least one processor may be additionally configured to transmit the M-plane message to the RU. The M-plane message may include mode information indicating the frequency offset factor.

According to one embodiment, the frame structure information may include bits to indicate the SCS. If the values of the bits fall within the first range, the identified frequency offset factor may be '0.5'. If the values of the bits belong to a second range that is different from the first range, the identified frequency offset factor may be '0.5'.

According to one embodiment, the plurality of frequency offset factors may further include '0.125' and '0.0625'.

According to one embodiment, the section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is the C-plane message. It can be included in the section information of the plane message. Alternatively, the section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for UE channel information transmission, and the frame structure information is included in the section extension information of the C-plane message. may be included.

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 a control plane (C-plane) message including frequency offset information and frame structure information indicating subcarrier spacing (SCS) from a distributed unit (DU);
An operation of identifying a frequency offset factor among a plurality of frequency offset factors;
Obtaining a frequency offset value corresponding to the product of the frequency offset information, the SCS, and the frequency offset factor;
Including transmitting a downlink signal based on the frequency offset value,
The method wherein the plurality of frequency offset factors include '0.5' and '0.25'.
In claim 1,
The method further includes receiving from the DU a management plane (M-plane) message including mode information indicating the frequency offset factor.
In claim 1,
The frame structure information includes bits to indicate the SCS,
If the values of the bits fall within the first range, the identified frequency offset factor is '0.5',
When the values of the bits belong to a second range different from the first range, the identified frequency offset factor is '0.5'.
The method of claim 1, wherein the plurality of frequency offset factors further include '0.125' and '0.0625'.
In claim 1,
The section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is included in the section information of the C-plane message. included in, or
The section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for transmitting UE channel information, and the frame structure information is included in the section extension information of the C-plane message. method.
In the method performed by a distributed unit (DU),
An operation of determining frequency offset information related to a frequency offset factor among a plurality of frequency offset factors;
An operation of transmitting a control plane (C-plane) message including section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a radio unit (RU). Including,
The frequency offset factor is provided to the RU by a management plane (M-plane) message or the C-plane message,
The frequency offset value applied to the downlink signal corresponds to the product of the frequency offset information, the SCS, and the frequency offset factor,
The method wherein the plurality of frequency offset factors include '0.5' and '0.25'.
In claim 6,
Further comprising transmitting the M-plane message to the RU,
The M-plane message includes mode information indicating the frequency offset factor.
In claim 6,
The frame structure information includes bits to indicate the SCS,
If the values of the bits fall within the first range, the identified frequency offset factor is '0.5',
When the values of the bits belong to a second range different from the first range, the identified frequency offset factor is '0.5'.
The method of claim 6, wherein the plurality of frequency offset factors further include '0.125' and '0.0625'.
In claim 6,
The section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is included in the section information of the C-plane message. included in, or
The section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for transmitting UE channel information, and the frame structure information is included in the section extension information of the C-plane message. 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 a control plane (C-plane) message from a distributed unit (DU) containing information indicating frequency offset information and subcarrier spacing (SCS),
Identifying a frequency offset factor among a plurality of frequency offset factors,
Obtaining a frequency offset value corresponding to the product of the frequency offset information, the SCS, and the frequency offset factor,
Configured to transmit a downlink signal based on the frequency offset value,
The electronic device wherein the plurality of frequency offset factors include '0.5' and '0.25'.
The method of claim 11, wherein the at least one processor:
An electronic device further configured to receive a management plane (M-plane) message including mode information indicating the frequency offset factor from the DU.
In claim 11,
The frame structure information includes bits to indicate the SCS,
If the values of the bits fall within the first range, the identified frequency offset factor is '0.5',
When the values of the bits belong to a second range different from the first range, the identified frequency offset factor is '0.5'.
The electronic device of claim 11, wherein the plurality of frequency offset factors further include '0.125' and '0.0625'.
In claim 11,
The section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is included in the section information of the C-plane message. included in, or
The section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for transmitting UE channel information, and the frame structure information is included in the section extension information of the C-plane message. 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,
Determine frequency offset information related to the frequency offset factor among a plurality of frequency offset factors,
Configured to transmit a control plane (C-plane) message including section information for a downlink signal, the frequency offset information, and information indicating subcarrier spacing (SCS) to a radio unit (RU). become,
The frequency offset factor is provided to the RU by a management plane (M-plane) message or the C-plane message,
The frequency offset value applied to the downlink signal corresponds to the product of the frequency offset information, the SCS, and the frequency offset factor,
The electronic device wherein the plurality of frequency offset factors include '0.5' and '0.25'.
The method of claim 16, wherein the at least one processor:
Additionally configured to transmit the M-plane message to the RU,
The M-plane message includes mode information indicating the frequency offset factor.
In claim 16,
The frame structure information includes bits to indicate the SCS,
If the values of the bits fall within the first range, the identified frequency offset factor is '0.5',
When the values of the bits belong to a second range different from the first range, the identified frequency offset factor is '0.5'.
The electronic device of claim 16, wherein the plurality of frequency offset factors further include '0.125' and '0.0625'.
In claim 16,
The section type of the C-plane message is section type 3, which is used for physical random access channel (PRACH) and mixed-numerology channels, and the frame structure information is included in the section information of the C-plane message. included in, or
The section type of the C-plane message is section type 5 for UE (user equipment) scheduling information or section type 6 for transmitting UE channel information, and the frame structure information is included in the section extension information of the C-plane message. Electronic devices.

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