KR102583524B1 - Method and apparatus for transmitting and receiving a signal using a beamforming in a communication system - Google Patents

Abstract

This disclosure relates to 5G or pre-5G communication systems to support higher data rates after 4G communication systems such as LTE. A method of transmitting and receiving a signal in a terminal of a mobile communication system according to an embodiment of the present specification includes receiving first information including an information request related to a beam from a base station; Transmitting second information including beam-related information based on the first information to the base station; and changing at least one of a transmission beam and a reception beam associated with the base station based on the first information and the second information. According to an embodiment of the present specification, each node in a communication system can efficiently exchange at least one of beam change information and control information for applying beamforming.

Description

{Method and apparatus for transmitting and receiving a signal using a beamforming in a communication system}

Embodiments of the present specification relate to a method for transmitting and receiving information for transmitting and receiving signals through beamforming in a communication system and a device using the same. More specifically, it relates to a method for changing at least one of a transmission beam and a reception beam at each node that transmits and receives signals in a communication system using beamforming, and a device using the same.

In order to meet the increasing demand for wireless data traffic following the commercialization of the 4G communication system, efforts are being made to develop an improved 5G communication system or pre-5G communication system. For this reason, the 5G communication system or pre-5G communication system is called a Beyond 4G Network communication system or a Post LTE system.

To achieve high data rates, 5G communication systems are also being considered for implementation in ultra-high frequency (mmWave) bands (such as the 60 GHz band). In the 5G communication system, beamforming, massive array multiple input/output (massive MIMO), full dimension multiple input/output (FD-MIMO), array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, to improve the network of the system, the 5G communication system uses advanced small cells, advanced small cells, cloud radio access networks (cloud RAN), and ultra-dense networks. , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation. Technology development is underway.

In addition, the 5G system uses FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (ACM) methods, and advanced access technologies such as FBMC (Filter Bank Multi Carrier) and NOMA. (non-orthogonal multiple access), and SCMA (sparse code multiple access) are being developed.

Additionally, beamforming can be applied in the digital domain and analog domain in the base station/terminal of the communication system. Additionally, for analog beamforming, an appropriate beam must be applied and methods and devices for effectively transmitting and receiving such information are required.

Embodiments of the present specification are proposed to solve the above-mentioned problems, and one purpose is to provide a method and device for transmitting and receiving beam change and control information for operating analog beamforming in a communication system. Another purpose of the embodiments of the present specification is to provide a method of operating a base station and a terminal for transmitting and receiving beam change and control information for operating analog beamforming to achieve a high data transmission rate, and a device using the same.

In order to achieve the above-described problem, a method of transmitting and receiving a signal in a terminal of a mobile communication system according to an embodiment of the present specification includes receiving first information including an information request related to a beam from a base station; Transmitting second information including beam-related information based on the first information to the base station; and changing at least one of a transmission beam and a reception beam associated with the base station based on the first information and the second information.

A method of transmitting and receiving a signal at a base station of a mobile communication system according to another embodiment of the present specification includes transmitting first information including an information request related to a beam to a terminal; Receiving second information including information related to a beam based on the first information from the terminal; and changing at least one of a transmission beam and a reception beam related to the terminal based on the first information and the second information.

A terminal of a mobile communication system according to another embodiment of the present specification includes a transceiver unit for transmitting and receiving signals; And controlling the transceiver, receiving first information including a request for information related to the beam from the base station, transmitting second information including information related to the beam based on the first information to the base station, and and a control unit that changes at least one of a transmission beam and a reception beam related to the base station based on the first information and the second information.

A base station of a mobile communication system according to another embodiment of the present specification includes a transceiver unit that transmits and receives signals; And controlling the transceiver, transmitting first information including an information request related to the beam to the terminal, receiving second information including information related to the beam based on the first information from the terminal, and and a control unit that changes at least one of a transmission beam and a reception beam related to the terminal based on the first information and the second information.

According to an embodiment of the present specification, each node in a communication system can efficiently exchange at least one of beam change information and control information for applying beamforming, and through this, manage, select, and apply a beam suitable for the channel environment. Communication efficiency can be improved.

1 is a diagram for explaining a beamforming operation in a wireless communication system.
Figure 2 is a diagram showing a method for managing a beam list according to an embodiment of the present specification.
Figure 3 is a diagram showing a method for managing a beam list according to another embodiment of the present specification.
FIG. 4 is a diagram illustrating an uplink (UL) downlink control information (DCI)-based beam control method according to an embodiment of the present specification.
Figure 5 is a diagram showing a UL DCI-based beam control method according to another embodiment of the present specification.
Figure 6 is a diagram showing a UL DCI-based beam control method according to another embodiment of the present specification.
Figure 7 is a diagram showing a downlink (DL) DCI-based beam control method according to an embodiment of the present specification.
Figure 8 is a diagram showing a DL DCI-based beam control method according to another embodiment of the present specification.
Figure 9 is a diagram showing a DL DCI-based beam control method according to another embodiment of the present specification.
Figure 10 is a diagram showing a beam control method based on MAC-CE (medium access control-control element) according to an embodiment of the present specification.
Figure 11 is a diagram showing a beam control method according to an embodiment of the present specification.
FIG. 12 is a diagram illustrating a beam control method based on the beam control identifier included in DCI according to an embodiment of the present specification.
FIG. 13 is a diagram illustrating a beam control method based on a beam control identifier included in DCI according to another embodiment of the present specification.
FIG. 14 is a diagram illustrating a beam control method based on the beam control identifier included in the beam information reporting message according to an embodiment of the present specification.
FIG. 15 is a diagram illustrating a beam control method based on a beam control identifier included in a beam information reporting message according to another embodiment of the present specification.
FIG. 16 is a diagram illustrating a method of controlling a beam through a confirmation message based on a beam control identifier included in a beam information reporting message according to an embodiment of the present specification.
FIG. 17 is a diagram illustrating a method of controlling a beam through a confirmation message based on a beam control identifier included in a beam information reporting message according to another embodiment of the present specification.
FIG. 18 is a diagram illustrating a method of changing a beam based on a threshold value according to an embodiment of the present specification.
FIG. 19 is a diagram illustrating a method of changing a beam based on a threshold value according to another embodiment of the present specification.
FIG. 20 is a diagram illustrating a method of changing a beam based on a threshold value according to another embodiment of the present specification.
Figure 21 is a diagram showing a selective beam change method according to an embodiment of the present specification.
Figure 22 is a diagram showing a terminal according to an embodiment of the present specification.
Figure 23 is a diagram showing a base station according to an embodiment of the present specification.

Hereinafter, embodiments of the present specification will be described in detail with reference to the attached drawings.

In describing the embodiments, descriptions of technical content that is well known in the technical field of this specification and that are not directly related will be omitted. This is to convey the point more clearly and not obscure it by omitting unnecessary explanations.

For the same reason, some components are exaggerated, omitted, or schematically shown in the accompanying drawings. Additionally, the size of each component does not entirely reflect its actual size. In each drawing, identical or corresponding components are assigned the same reference numbers.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to provide common knowledge in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

At this time, it will be understood that each block of the processing flow diagram diagrams and combinations of the flow diagram diagrams can be performed by computer program instructions. These computer program instructions can be mounted on a processor of a general-purpose computer, special-purpose computer, or other programmable data processing equipment, so that the instructions performed through the processor of the computer or other programmable data processing equipment are described in the flow chart block(s). It creates the means to perform functions. These computer program instructions may also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular manner, so that the computer-usable or computer-readable memory It is also possible to produce manufactured items containing instruction means that perform the functions described in the flowchart block(s). Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer, thereby generating a process that is executed by the computer or other programmable data processing equipment. Instructions that perform processing equipment may also provide steps for executing the functions described in the flow diagram block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). Additionally, it should be noted that in some alternative execution examples it is possible for the functions mentioned in the blocks to occur out of order. For example, it is possible for two blocks shown in succession to be performed substantially at the same time, or it is possible for the blocks to be performed in reverse order depending on the corresponding function.

At this time, the term '~unit' used in this embodiment refers to software or hardware components such as FPGA or ASIC, and the '~unit' performs certain roles. However, '~part' is not limited to software or hardware. The '~ part' may be configured to reside in an addressable storage medium and may be configured to reproduce on one or more processors. Therefore, as an example, '~ part' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and 'parts' may be combined into a smaller number of components and 'parts' or may be further separated into additional components and 'parts'. Additionally, components and 'parts' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card.

For the purpose of explaining the embodiment, the description is based on a communication system to which beamforming is applied. However, the embodiments of the specification are not limited to such a system, and the gist of each embodiment can be universally applied to other systems.

Additionally, throughout the embodiment, information transmitted and received for beam control may include information transmitted and received for beam change, and beam control may be referred to as beam change.

1 is a diagram for explaining a beamforming operation in a wireless communication system.

A wireless communication system includes a plurality of nodes (e.g., a base station and a plurality of terminals), and one node finds the optimal beam for wireless communication with the other node and selects the optimal beam to transmit and receive data using the beam. You can set it. In an embodiment, at least one of analog beamforming and digital beamforming may be applied for beamforming. Analog beamforming can be performed by adjusting the shape and direction of the beam using differences in amplitude and phase of the carrier signal in the RF band. Digital beamforming processes signals by adding each weight vector to the digitized signal, and the RF signal from each antenna passes into the digital band through an individual RF transmitter/receiver. Digital beamforming can implement beamforming through digital signal processing, creating a sophisticated beam according to communication needs depending on signal processing capabilities.

Each node can form a transmission beam (Tx beam) and a reception beam (Rx beam), and in order for each node to find a suitable beam for communication, the total beam is divided by the number of transmission beams and reception beams, as shown in FIG. 1. A full beam sweep can be performed. The process of finding the optimal beam for the counterpart node can be called beam searching, and for this purpose, related reference signals can be transmitted and received.

Throughout the embodiment, the reference signal may include a cell-specific reference signal and a terminal-specific reference signal, and each signal may be transmitted periodically or aperiodically. Examples of reference signals may include a beam reference signal (BRS) and a beam refinement reference signal (BRRS).

In an embodiment, the BRS may be transmitted periodically and may be a cell-specific reference signal. Additionally, in an embodiment, BRRS is a UE-specific reference signal and may be transmitted aperiodically. In another embodiment, BRRS is a UE-specific reference signal, and BRRS can be allocated statically or semi-statically, and can be transmitted periodically or aperiodically within the allocated period.

In an embodiment, the terminal may measure at least one of the BRS and BRRS transmitted from the base station and report information about specific beams among them to the base station. Information reported to the base station may include at least one of the following.

- BRS-based Beam state information (BSI): beam index (BI) of the corresponding beam and quality information (quality) of the corresponding beam (e.g., beam reference signal received power (BRSRP), beam reference signal quality (BRSRQ), beam received signal strength indicator (BRSSI).)

- BRRS-based Beam refinement information (BRI): BRRS resource index (BRRS-RI) for classification of BRRS beams and quality information of the corresponding beam (e.g., BRRS received power (BRRS-RP))

The information about the beam may be transmitted through an uplink channel transmitted from the terminal to the base station, and may be transmitted through at least one of an uplink control channel and a data channel. The base station maintains and updates beam information for each terminal through a signaling process in which the base station requests the terminal to report beam information and the terminal transmits information about specific beams in response to the request. In an embodiment of the present specification, a method in which a base station transmits control information including a command related to beam change to a control message and performs a beam change according to the command, and a device using the same are described. The beam change command is explained as a representative example of LTE-based downlink control information (DCI) or medium access control-control element (MAC-CE), and there is no limitation on the type of control message used.

The base station can set a common beam list for changing the beam of at least one of the BSI or BRI-based base station and the terminal reported from the terminal. In embodiments, setting or updating the beam list may be performed through one or more of the following two methods.

Update method 1: Information on the optimal N beams (Best N beams) is reported to the base station periodically or aperiodically based on at least one of the BRSRP and BRRS-RP measured by the terminal, and through this, the terminal and the base station Information about Best N beam can be maintained, and the maintained information can also be updated. In an embodiment, N may be a preset natural number and may be variably applied through information exchange between the base station and the terminal. Additionally, the number of N can be flexibly adjusted depending on the channel environment.

Update method 2: The base station receives Best N beam information from the terminal periodically or aperiodically, and based on the received information, the base station generates a beam list by applying preset standards and sends the generated beam list information to the terminal. You can update the beam list by transmitting.

In update method 1, information for beam list application can be exchanged between the base station and the terminal without additional signaling, and in update method 2, the base station shares information about the beam list with the terminal through specific signaling or message transmission. Even in the case of update method 1, the base station can share beam list information modified for a specific purpose with the terminal, and in this way, the beam list can be maintained and updated by applying at least one of update methods 1 and 2.

In order for the base station to transmit beam list-related information to the terminal, specific signaling or message transmission is possible, and the following methods can be applied.

- A method of transmitting beam list related information to the terminal using at least one of higher layer signaling, DCI, and MAC-CE including at least one of RRC (radio resource control) and SI (system information) - DL DCI + xPDSCH ( In the case of (phsycal downlink shared channel), a method of transmitting beam list-related information to the terminal using xPDSCH transmitted from the base station to the terminal based on the DL grant allocated in DCI

- In the case of UL DCI + xPUSCH (physical uplink shared channel), beam list-related information is transmitted through DCI and ACK/NACK information for the corresponding content is received from the terminal through xPUSCH.

- In the case of UL DCI + xPUCCH (physical uplink control channel), beam list-related information is transmitted through DCI and ACK/NACK information for the corresponding content is received from the terminal through xPUCCH - Additional necessary information while transmitting beam list information Indication information can be transmitted simultaneously in the same signal or separately in another signal. For example, when the base station refers to a specific beam to be applied to beam change among a plurality of beam lists, or refers to a beam set, indication information necessary for beam change can be included and transmitted to the terminal.

In an embodiment, DCI may be transmitted from the base station to the terminal through xPDCCH (physical downlink control channel).

Additionally, in an embodiment, xPDSCH, xPUSCH, xPUCCH, and xPDCCH may each be a modified example of PDSCH, PUSCH, PUCCH, and PDCCH, or may be the same configuration.

As an example, when transmitting information related to the beam list to the terminal through MAC CE, it is also possible to indicate each beam included in the list using a bit map method. The sort order of the bit map may change depending on decoding. The size of each field can be changed. An example of each field is as follows.

In an embodiment, xPUSCH and xPUCCH may be the same or similar channels as PUSCH and PUCCH, respectively.

Indication bits Beam indication 00 # One 01 #3 10 # 2 11 #7

Table 1 shows an example of a beam list according to an embodiment of the present specification. The indication bit is information transmitted to indicate a beam included in the beam list, and the beam indication indicates the beam index corresponding to the indication bit.

If the beam list is shared between base station terminals, the base station can use it to indicate the beam for a specific purpose. For example, the base station can be used to designate a specific beam and indicate a change to that beam, or to designate a beam that the terminal cannot use and control the change to that beam. In an embodiment, 2 bits may be used to indicate the beam, and this may be variably applied. Additionally, the beam index corresponding to each indication bit may be updated according to the terminal's report or the base station's needs. More specifically, the correspondence between indication bit and beam indication can be updated based on beam-related information reported by the terminal. More specifically, when the base station transmits control information including indication bits of 01 to the terminal to change the beam, the terminal can use the beam corresponding to #3 to transmit and receive signals with the base station based on this.

Additionally, in an embodiment, in response to transmitting the beam list information, at least one of the base station and the terminal may change the beam applied to communication between them. More specifically, the base station transmits a beam list to the terminal, and from a certain point after transmitting the beam list, the terminal and base station are set to change the beam to the index (#1 in Table 1) indicated by the most significant bit (00 in Table 1). You can. The beam change may be selectively applied to all channels or only to specific channel groups.

Indication bits Beam indication 00 UL: #2, DL: #1 01 UL: #1, DL: #3 10 UL: #3, DL: #2 11 UL: #7, DL: #7

Table 2 shows another example of a beam list according to an embodiment of the present specification. Indication bit is information transmitted to indicate a beam included in the beam list, and beam indication indicates a beam index corresponding to the indication bit. In an embodiment, each indication bit may indicate a different or the same uplink and downlink beam. In this example, the UL beam list and the DL beam list are operated separately, and the base station can transmit information about the two beam lists to the terminal.

If the beam list is shared between base station terminals, the base station can use it to indicate the beam for a specific purpose. For example, the base station can indicate a specific beam and change to the indicated beam. Additionally, depending on the embodiment, the base station may indicate a beam that the terminal cannot use, and may also be used to control the terminal's use of the corresponding beam.

In an embodiment, when the base station transmits 10 as an indication bit to the terminal, the terminal may apply the beam corresponding to #3 in the uplink and the beam corresponding to #2 in the downlink.

Additionally, in an embodiment, in response to transmitting the beam list information, at least one of the base station and the terminal may change the beam applied to communication between them. More specifically, the base station transmits a beam list to the terminal, and from a specific point in time after transmitting the beam list, the terminal and the base station can change the beam to a beam corresponding to a feature index among the beam list. More specifically, the terminal and the base station change the beam to the beam corresponding to #1 indicated by 00 from a specific point in time in the first channel group (e.g. DL), and 01 is indicated in the second channel group (e.g. UL) from a specific point in time. You can change the beam to the beam corresponding to #1. Channel groups can be applied in various ways as described in the embodiments below, and changed beams may be applied only to some channels, such as control channels or data channels in downlink or uplink.

In one embodiment, when the base station needs to receive all users' data signals with one beam for multiplexing of UL multiple users, the base station temporarily orders the users subject to multiplexing to change to the same base station beam. After transmission and reception of uplink data (UL data) is completed, each user can change the beam to the existing beam or a new optimal beam. The above embodiment can be used when changing the common beam of a base station or multiple terminals is required in addition to uplink multi-user MIMO (UL MU-MIMO).

Additionally, in an embodiment, when managing the beam list based on four lists as shown in Table 2, some indexes may provide beam information for the first group, and other indexes may provide beam information for the second group. More specifically, 00 and 10 may include beam information for the first group, and 10 and 11 may include beam information for the second group. At this time, the beam information of each two groups may be updated through the same signal or may be updated separately.

The beam can be set to change to the index (#1 in Table 1) indicated by the most significant bit (00 in Table 1). The beam change may be selectively applied to all channels or only to specific channel groups.

In this embodiment, since two beam lists are operated, the base station can additionally signal information about which beam to indicate from which beam list.

Additionally, depending on how the indication bit is transmitted, it may be determined whether it indicates an uplink beam or a downlink beam. More specifically, when the indication bit is transmitted through DL DCI, only the beam corresponding to the downlink is changed to the downlink beam corresponding to the indication bit, and when the indication bit is transmitted through UL DCI, only the beam corresponding to the uplink is changed to the indication bit. can be changed to an uplink beam.

Figure 2 is a diagram showing a method for managing a beam list according to an embodiment of the present specification.

Referring to FIG. 2, in the embodiment, the terminal 201 can transmit and receive signals with the base station 202.

In step 210, the base station 202 may transmit a reference signal to the terminal 201. In an embodiment, the reference signal may include at least one of BRS and BRRS.

In step 215, the terminal 201 can determine N beams with the best quality (best N beams) based on the received reference signal. In an embodiment, N may be a natural number preset between the base station 202 and the terminal 201.

In step 220, the terminal 210 may transmit the measured beam information to the base station 202. In an embodiment, the terminal may transmit information about some or all of the N beams.

In step 225, the base station may update beam list information based on the received information. In one embodiment, the same beam list is managed between the terminal 201 and the base station 202, and based on this, the index of the beam that changes when the beam is changed can be indicated.

Figure 3 is a diagram showing a method for managing a beam list according to another embodiment of the present specification.

Referring to Figure 3, the terminal 301 and the base station 302 can transmit and receive signals.

In step 310, the terminal 301 may transmit the measured beam information to the base station 302. In an embodiment, the terminal 301 may generate beam information based on a reference signal received from the base station 302, and transmit the beam information to the base station 302 by changing some information in the previously managed beam list. It may be possible.

In step 315, the base station 302 may update beam list information based on the received information. In an embodiment, the beam list may include N beams determined based on information transmitted and received between the terminal and the base station, and index information indicating each beam may also be generated.

In step 320, the base station 302 may transmit updated beam list information to the terminal 301. The updated beam list information may be transmitted as a higher layer signal including RRC or SIB, and may also be transmitted through a downlink data channel or downlink control channel.

In step 325, the terminal 301 can transmit and receive signals with the base station 302 based on the received beam list information.

Resource allocation on a downlink (DL) or uplink (UL) channel by the terminal may be performed based on downlink control information (DCI) transmitted by the base station. Below, as an example, a method for changing a beam based on DCI will be described.

FIG. 4 is a diagram illustrating an uplink (UL) downlink control information (DCI)-based beam control method according to an embodiment of the present specification.

Referring to FIG. 4, the terminal 401 and the base station 402 can transmit and receive signals. Signals can be transmitted and received.

In step 410, the base station 402 may transmit UL DCI including beam change information to the terminal 401. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 415, the terminal 401 may change the beam for transmitting and receiving signals to and from the base station 402 based on the received information. More specifically, signal transmission can be performed by applying a changed beam corresponding to the UL channel transmission time indicated through the UL DCI. Additionally, in step 420, the base station 402 may change the beam corresponding to the terminal 401 based on the information transmitted in step 410. The beam change can be performed simultaneously in the base station 402 and the terminal 401, but is not limited to this, and can be changed at a timing that can transmit and receive at least one of xPUCCH and xPUSCH transmitted based on the UL DCI. There is.

In step 425, the terminal 401 may transmit at least one of xPUCCH and xPUSCH by applying the changed beam.

In this embodiment, the base station 402 indicates beam information to the terminal 401 through UL DCI, and beam changes of the terminal and base station can be performed in response to transmission and reception of the UL channel allocated by the UL DCI. In addition, by changing the transmission beam and reception beam of the base station and the terminal in response to the transmission of the channel indicated through DCI, signal transmission and reception through the changed beam is possible.

Figure 5 is a diagram showing a UL DCI-based beam control method according to another embodiment of the present specification.

Referring to Figure 5, the terminal 501 and the base station 502 can transmit and receive signals. Signals can be transmitted and received.

In step 510, the base station 502 may transmit UL DCI including beam change information to the terminal 501. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 515, the terminal 501 may transmit at least one of xPUCCH and xPUSCH indicated by the UL DCI.

As a first modified example of this embodiment, in steps 520 and 525, the terminal 501 and the base station 502 may each perform a beam change based on the information included in the message transmitted in step 510, and the changed beam accordingly In step 530, the base station 502 transmits an ACK message to the terminal, and the terminal 501 can receive the ACK message through the changed beam.

As a second modified example of this embodiment, an ACK message may be transmitted from the base station 502 to the terminal 501 in step 530, and the base station 502 based on steps 535 and 540 in response to at least one of transmitting and receiving the ACK message. ) and the beam of the terminal 501 can be changed.

In this embodiment, the base station 502 instructs the terminal 501 with beam information through UL DCI, and in response to the transmission of ACK information for the uplink channel, provides information on at least one of each transmission beam and reception beam. Changes can be made.

Figure 6 is a diagram showing a UL DCI-based beam control method according to another embodiment of the present specification.

Referring to FIG. 6, the terminal 601 and the base station 602 can transmit and receive signals. Signals can be transmitted and received.

In step 610, the base station 602 may transmit UL DCI including beam change information to the terminal 601. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 615, the terminal 601 may transmit at least one of xPUCCH and xPUSCH indicated by the UL DCI.

In step 620, the base station 602 may transmit an ACK corresponding to at least one of xPUCCH and xPUSCH to the terminal 601 in subframe n.

In steps 625 and 630, the base station 602 and the terminal 601 may apply a beam changed according to the beam change information in subframe n+k based on the received ACK, respectively. More specifically, the changed beam information can be applied to signals transmitted or received after subframe n+k. In an embodiment, the k value may be a preset value. Additionally, the k value may be transmitted from the base station 602 to the terminal 601 through a higher layer signal including at least one of RRC and SIB, or may be transmitted by being included in the UL DCI transmitted in step 610. Additionally, in an embodiment, the k value may be 0, and in this case, the base station and the terminal can change the beam after the ACK transmission and reception point.

Figure 7 is a diagram showing a downlink (DL) DCI-based beam control method according to an embodiment of the present specification.

Referring to FIG. 7, the terminal 701 can transmit and receive signals with the base station 702.

In step 710, the base station 702 may transmit DL DCI including beam change information to the terminal 701. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 715, beam change can be performed according to the beam change information. More specifically, in response to performing downlink channel transmission indicated through the DL DCI, the base station 702 may change the beam corresponding to the terminal 701, and in step 720, the terminal 701 also transmits the DL DCI. The beam corresponding to the base station 702 can be changed based on the information indicated in .

In step 725, the base station 702 may transmit at least one of xPDCCH and xPDSCH to the terminal 701 through the changed beam, and the terminal 701 may receive at least one of the xPDCCH and xPDSCH through the changed beam.

In an embodiment, the terminal beam change may be performed simultaneously with the base station beam change, but is not limited thereto, and the beam change may be performed at a time appropriate for signal reception corresponding to step 725.

Figure 8 is a diagram showing a DL DCI-based beam control method according to another embodiment of the present specification.

Referring to FIG. 8, the terminal 801 can transmit and receive signals with the base station 802.

In step 810, the base station 802 may transmit DL DCI including beam change information to the terminal 801. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 815, the base station 802 may transmit at least one of xPDCCH and xPDSCH indicated by the DL DCI to the terminal 801.

As a first modified example of this embodiment, in step 820, the terminal 801 may change the beam corresponding to the base station 802 based on the DL DCI. In an embodiment, the terminal 801 can change the transmission beam and the reception beam corresponding to the base station 802, and when changing the beam, can change at least one of the control channel, the data channel, and the beam related to the reference signal, step 825 The base station 802 may change the beam corresponding to the terminal 801 based on the DL DCI.

In step 830, the terminal 801 may transmit an ACK for at least one of the xPDCCH and xPDSCH indicated by the DL DCI to the base station 802. More specifically, in step 820, the terminal 801 may transmit an ACK for at least one of the xPDCCH and xPDSCH indicated by the DL DCI to the base station 802 based on the changed beam. Additionally, the base station 802 can receive the ACK from the terminal 801 based on the changed beam.

As a second modified example of this embodiment, an ACK message may be transmitted from the terminal 801 to the base station 802 in step 830, and the base station 802 based on steps 835 and 840 in response to at least one of transmitting and receiving the ACK message. ) and the beam of the terminal 801 can be changed. In this embodiment, the time when the terminal beam and the base station beam are changed may be the same, but is not limited to this, and the ACK message of step 830 can be transmitted and received with the changed beam. You can decide when to change the beam.

In this way, after transmission of the downlink channel, beam changes of the base station and the terminal can be performed in response to the timing of transmission and reception of ACK regarding reception of the corresponding channel.

Figure 9 is a diagram showing a DL DCI-based beam control method according to another embodiment of the present specification.

Referring to Figure 9, the terminal 901 can transmit and receive signals with the base station 902.

In step 910, the base station 902 may transmit DL DCI including beam change information to the terminal 901. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 915, the base station 902 may transmit at least one of xPDCCH and xPDSCH indicated by the DL DCI to the terminal 901.

In step 920, the terminal 901 may transmit an ACK for at least one of the xPDCCH and xPDSCH indicated by the DL DCI to the base station 902 in subframe n.

In steps 925 and 930, the terminal 901 and the base station 902 may change beams corresponding to the base station 902 and the terminal 901, respectively, in subframe n+k based on the DL DCI. More specifically, after subframe n+k, the terminal 901 and the base station 902 can transmit and receive signals based on the beam indicated by the DL DCI. In an embodiment, the k value may be a preset value. Additionally, the k value may be transmitted from the base station 902 to the terminal 901 through a higher layer signal including at least one of RRC and SIB, or may be transmitted by being included in the DL DCI transmitted in step 910. Additionally, in an embodiment, the k value may be 0, and in this case, the base station and the terminal can change the beam after the ACK transmission and reception point.

In this embodiment, the terminal can change the transmission beam or reception beam corresponding to the base station based on the UL or DL DCI transmitted by the base station, and the base station can also change the transmission beam or reception beam corresponding to the terminal. The timing of changing the indicated beam based on the DCI may vary depending on the embodiment described above.

As an example, the base station may transmit DCI including beam change information to the terminal. The DCI includes at least one BI or BRRS-RI, and may also include indication information for a specific channel or channel group corresponding to the BI or BRRS-RI. In response to this, the base station and the terminal can each transmit and receive channels designated within the DCI field through corresponding beams. In this way, by indicating the channel to which the changed beam will be applied in the DCI, signals can be transmitted and received by applying the changed beam only to channel transmission of some of the downlink channel and uplink channel.

In another embodiment, the base station may indicate to the terminal a beam for the DL channel and a beam for the UL channel within the DCI, and based on this, the base station and the terminal transmit and receive signals by applying different or the same beam to the DL channel and the UL channel. can do.

Additionally, in an embodiment, if the beam change information is transmitted through DL DCI, the beam change information is applied only to downlink-related beam changes, and if the beam change information is transmitted through UL DCI, the beam change information is applied only to uplink beam changes. It can be applied. However, when giving a UL DCI / DL DCI beam change command, it is not limited to performing beam change mapping for the UL channel / DL channel, but a specific channel, a specific channel group, or the entire channel group can all be mapped to variably apply the beam change. You can.

Additionally, in an embodiment, when beam change-related control information is received, the changed beam may be continuously applied until the next beam change-related control information is received, or the beam change may be temporarily performed.

More specifically, scheduling can be performed on at least one of UL and DL channels through DCI, and at least one of BI and BRRS-RI can be included in the DCI and transmitted to the terminal. In this case, a beam change may be temporarily performed only for the UL and DL signals indicated through the DCI, and then the original beam may be returned. Additionally, depending on the embodiment, whether the beam change information will be temporarily applied may be indicated through separate indication or information in the DCI, or the application time may be set. The UL/DL channel indicated through the DCI also includes the UL/DL reference signal assigned through the DCI and can be equally applied to other channels. In the above embodiment, in the case of FIGS. 5 and 8, beam change can be applied not only to the corresponding UL/DL transmission but also to the corresponding ACK transmission and reception point, and in FIGS. 6 and 9, the beam change is applied within subframe n+k corresponding to a specific delay. A method of temporarily applying a change or a method of temporarily applying a beam change to a specific channel or channel group in the corresponding subframe n+k is also applicable. The specific channel or channel group may be preset or may be indicated based on at least one of DCI, MAC-CE, and RRC signaling. Additionally, in the above embodiment, when correcting Tx/Rx beams through BRRS, the method of indicating which Tx beam the BRRS comes down to can also be changed and applied. In other words, within the DCI that allocates BRRS, the base station indicates the beam index used when transmitting BRRS through the corresponding DCI, so that the terminal hears information about which beam the BRRS comes down to and uses it to set the Rx beam during BRRS-based correction. You can.

Figure 10 is a diagram showing a beam control method based on MAC-CE (medium access control-control element) according to an embodiment of the present specification.

Referring to FIG. 10, the terminal 1001 can transmit and receive signals with the base station 1002.

In step 1010, the base station 1002 may transmit a MAC-CE including beam change information to the terminal 1001. The beam change information may include indication information indicating a beam to be changed. More specifically, the beam change information includes at least one BI or BRRS-RI. Additionally, additional information related to the changing beam may be transmitted.

In step 1015, the terminal 1001 may transmit an ACK for the MAC-CE to the base station 1002 in subframe n.

In steps 1020 and 1025, the terminal 1001 and the base station 1002 may change beams corresponding to the base station 1002 and the terminal 1001, respectively, in subframe n+k based on the information included in the MAC-CE. . More specifically, after subframe n+k, the terminal 1001 and the base station 1002 can transmit and receive signals based on the beam indicated by the information included in the MAC-CE. In an embodiment, the k value may be a preset value. Additionally, the k value may be transmitted from the base station 1002 to the terminal 1001 through a higher layer signal including at least one of RRC and SIB, or may be transmitted by being included in the MAC-CE transmitted in step 1010. Additionally, in an embodiment, the k value may be 0, and in this case, the base station and the terminal can change the beam after the ACK transmission and reception point.

In an embodiment, when transmitting a beam change command or beam information to MAC-CE, an instruction regarding a specific channel or channel group may be given, and information regarding BI or BRRS-RI to be applied to the group may be transmitted, and the base station and terminal may transmit the above information. Depending on the information, a beam change can be performed from the time a specific delay is applied to the indicated beam for the designated channel. Similar to transmitting beam control information through DCI, beam change information can also be temporarily transmitted and received.

Additionally, in an embodiment, when updating beam list information corresponding to FIGS. 1 and 2, beam change may be performed by transmitting beam control information. The base station and the terminal can each manage a commonly used beam list, and depending on the embodiment, the base station may maintain and update the same beam list between the terminal and the base station by transmitting information related to the beam list to the terminal. In an embodiment, when managing a list of N beams, the base station may periodically or aperiodically transmit beam index-related information to the terminal. In an embodiment, when updating beam information like this, beam information change may be performed at the same time. At this time, the corresponding beam update information may be transmitted to the terminal by being included in at least one of a DCI, a higher layer signal including an RRC message, and a control message (e.g. MAC-CE). It can be applied using various types of signaling.

Hereinafter, embodiments of the beam control method and beam change method according to the embodiments of the present specification will be described, and additionally, selective beam change and error case handling method when beam change will be described.

Figure 11 is a diagram showing a beam control method according to an embodiment of the present specification.

Referring to FIG. 11, the terminal 1101 can transmit and receive signals with the base station 1102.

In step 1110, the base station 1102 may transmit information requesting one of BSI and BRI to the terminal 1101. In one embodiment, the information may be transmitted to the terminal through DCI.

In step 1115, the terminal 1101 may transmit at least one of BSI and BRI to the base station 1102 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality.

In step 1120, the base station 1102 may change the beam in subframe n+k based on the information received in step 1115. More specifically, based on the received beam information, the base station 1102 may change the beam if at least one of the corresponding beams BRSRP and BRRS-RP is better compared to the beam currently in use. Additionally, in step 1125, the terminal 1101 may change the beam in subframe n+k based on the information transmitted in step 1115. More specifically, based on the transmitted beam information, the terminal 1101 may change the beam if at least one of the corresponding beams BRSRP and BRRS-RP is better compared to the beam currently in use. In an embodiment, the beam change may be performed simultaneously in the base station and the terminal in the corresponding subframe, but is not limited to this, and the beam change may be performed to transmit and receive signals with the changed beam in subsequent subframes including subframe n+k. there is.

In step 1130, the base station 1102 may transmit a signal to the terminal 1101 using the changed beam.

In the embodiment, the k value may be a preset value or may be indicated to the base station 1102 terminal by the method below.

More specifically, the k value may be indicated to the terminal in the DCI transmission. At least one bit may be allocated in DCI to indicate the k value, and an example of this is shown in Table 3. Table 3 discloses how the base station indicates the value of k to the terminal through 2 bits of information.

Indication bits Delay (k) 00 4 01 5 10 6 11 7

Referring to Table 3, the delay value can be determined according to each indication bit. The correspondence between the indication bits and delay values in Table 3 is arbitrary and may vary depending on implementation.

Additionally, in an embodiment, the k value may be indicated through different CRC masking when transmitting the DCI. More specifically, in the case of indication through different CRC masking when transmitting DCI, information may be transmitted by masking the CRC attached when transmitting DCI information with a different code. In an embodiment, a specific code may include all distinguishable codes, including orthogonal codes. Table 4 shows an example of indicating a delay value through CRC masking.

CRC mask Delay (k) 0000000000000000 4 1111111111111111 5 0101010101010101 6 1010101010101010 7

Referring to Table 4, the k value can be determined based on DCI's CRC masking. In an embodiment, the correspondence between CRC masking and k value may be applied differently.

Additionally, in an embodiment, when transmitting the DCI, different k values may be indicated through different scrambling sequences. More specifically, in order to indicate the value of k through different scrambling sequences when transmitting the DCI, the value of k can be indicated by applying different scrambling sequences to the DCI when transmitting the DCI.

Scrambling seq . Delay (k) a(i), i=0,… .,# of data symbol 4 b(i), i=0,… .,# of data symbol 5 c(i), i=0,… .,# of data symbol 6 d(i), i=0,… .,# of data symbol 7

Referring to Table 5, the k value can be indicated based on the scrambling sequence applied to DCI. The correspondence between the scrambling sequence and the k value is illustrative, and each correspondence may vary depending on implementation.

Additionally, the k value can be semi-statically specified through a higher layer signal including RRC, and a fixed value agreed upon between the terminal and the base station can be used. In another embodiment, the k value may be determined based on either information transmitted through RRC or DCI. For example, the k value can be determined based on the value transmitted through Asynchronous HARQ Timing.

Additionally, the k value may be indicated by a combination of at least two of the methods described above. For example, RRC Signaling notifies candidates for specific k values, and it is also possible to indicate which k value among the candidate values to apply through bits in DCI, CRC masking, and scrambling sequence.

Additionally, the k value can be applied as k1 + k2, and the base station can inform the terminal of k1 and k2 based on at least one of the methods for indicating k described above. As an example, k1 may be applied as a fixed value, and the base station may transmit the k2 value to the terminal with a variable value considering the channel situation.

Additionally, in an embodiment, an indicator indicating whether to change the beam may be included in the control information requesting the beam information report, and it may be determined whether to perform the beam change based on this.

FIG. 12 is a diagram illustrating a beam control method based on a beam control identifier (eg, beam change identifier) included in DCI according to an embodiment of the present specification.

Referring to FIG. 12, terminal 1201 can transmit and receive signals to and from the base station 1202.

In step 1210, the base station 1202 may transmit information requesting one of BSI and BRI to the terminal 1201, and the information may be transmitted to the terminal through DCI. In an embodiment, the DCI may include a beam control identifier (eg, beam change identifier). Figure 12 explains the process of transmitting whether or not the beam change is requested is indicated as on. The specific method for the beam change identifier will be described later.

In step 1215, the terminal 1201 may transmit at least one of the BSI and the BRI to the base station 1202 through at least one of the xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality.

In step 1220, since the beam change identifier is set to on in the DCI transmitted in step 1210, the base station 1202 can perform beam change in subframe n+k based on the information received in step 1215. In another embodiment, based on the received beam information, the base station beams only if at least one of the BRSRP and BRRS-RP of the corresponding beam is better than the threshold value to control beam change compared to the beam currently in use. Changes can be made. In embodiments, the k value can be determined using the methods previously described. The threshold value for controlling the beam change will be described later. In step 1225, the terminal 1201 may change the beam in subframe n+k based on the information transmitted in step 1210. The beam change of the terminal 1201 can also determine whether to change the beam based on the threshold value. In an embodiment, the beam change may be performed simultaneously in the base station and the terminal in the corresponding subframe, but is not limited to this, and the beam change may be performed to transmit and receive signals with the changed beam in subsequent subframes including subframe n+k. there is.

In step 1230, the base station 1202 may transmit a signal to the terminal 1201 using the changed beam, and the terminal 1201 may receive the signal using the changed beam.

In step 1230, the terminal 1201 may receive a signal using the changed beam. More specifically, the terminal 1201 may receive a signal using the beam reported in step 1215 in subsequent subframes including subframe n+k.

FIG. 13 is a diagram illustrating a beam control method based on a beam control identifier (eg, beam change identifier) included in DCI according to another embodiment of the present specification.

Referring to FIG. 13, the terminal 1301 can transmit and receive signals with the base station 1302.

In step 1310, the base station 1302 may transmit information requesting one of BSI and BRI to the terminal 1301, and the information may be transmitted to the terminal through DCI. In an embodiment, information indicating whether a beam change is requested to the DCI may be included, and in an embodiment, whether the beam change is requested may be indicated as off and transmitted. The specific method for the beam change identifier will be described later.

In step 1315, the terminal 1301 may transmit at least one of BSI and BRI to the base station 1302 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality.

In step 1320, the terminal 1301 and the base station 1302 may not change at least one of the transmission beam and the reception beam because the identifier indicating whether to change the beam included in step 1310 is displayed as off. In this way, the base station 1302 can report beam-related information to the terminal 1301 and may not perform beam changes. Additionally, depending on the embodiment, an additional beam change procedure may be performed by base station control.

Below, an example of a beam change identifier will be described.

According to one embodiment, in the above embodiment, whether to change the beam may be indicated through DCI for beam change control. More specifically, by including a specific bit in the DCI, it is possible to indicate whether to change the beam based on this. More specifically, when transmitting the DCI, if a specific indication bit is indicated as 0, beam change may not be performed, and if it is indicated as 1, beam change may be performed. Additionally, even if the specific indicator is displayed as 1, beam change may not be performed if the reported beam is the same as the current beam.

Additionally, it is possible to indicate whether or not to change the beam based on CRC masking and scrambling sequence.

CRC mask Beam change indication 0000000000000000 OFF 1111111111111111 ON

Referring to Table 6, it is possible to indicate whether to change the beam through different CRC masking when transmitting the DCI. For example, if the CRC of the DCI is composed of 16 bits, if the DCI is masked as 0000000000000000, it may mean that the beam change indicator is OFF, and if it is masked as 1111111111111111, it may mean that the beam change indicator is ON. This is one embodiment, and other correspondence relationships may also be applied.

Scrambling seq . Beam change indication a(i), i=0,… .,# of data symbol OFF b(i), i=0,… .,# of data symbol ON

Referring to Table 7, when transmitting the DCI, it is possible to indicate whether to change the beam by applying different scrambling sequences. As an example, it is possible to indicate ON and OFF whether to change the beam by applying a type of scrambling sequence as shown in Table 7.

Additionally, in an embodiment, whether to change the beam according to BSI and BRI requests may be semi-statically indicated through higher layer signaling such as RRC signaling.

Additionally, in an embodiment, when the terminal reports at least one of BSI and BRI, it may include information indicating whether to change the beam and apply whether or not to change the beam based on this.

FIG. 14 is a diagram illustrating a beam control method based on the beam control identifier included in the beam information reporting message according to an embodiment of the present specification.

Referring to FIG. 14, the terminal 1401 can transmit and receive signals with the base station 1402.

In step 1410, the base station 1402 may transmit information requesting one of BSI and BRI to the terminal 1401, and the information may be transmitted to the terminal through DCI.

In step 1415, the terminal 1401 may transmit at least one of BSI and BRI to the base station 1402 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality. Additionally, an identifier indicating whether to change the beam may be included and transmitted to the base station 1402 along with at least one of the BSI and BRI. In an embodiment, an indicator may be turned on and transmitted to indicate a beam change, and a method of displaying the indicator may include a method corresponding to that described in the above embodiment. More specifically, a bit indicating whether to directly change can be included in the channel transmitted in the uplink, or CRC masking can be applied differently, or scrambling code can be applied differently to indicate whether or not to change the beam.

In step 1420, since the beam change identifier is set to on in the information received in step 1415, the base station 1402 can perform beam change in subframe n+k based on the information received in step 1415. In another embodiment, based on the received beam information, the base station beams only if at least one of the BRSRP and BRRS-RP of the corresponding beam is better than the threshold value to control beam change compared to the beam currently in use. Changes can be made. The value of k can be determined using the methods previously described. The threshold value for controlling the beam change will be described later. In step 1425, the terminal 1401 may change the beam in subframe n+k based on the information transmitted in step 1410. The beam change of the terminal 1401 can also determine whether to change the beam based on the threshold value. In an embodiment, the beam change may be performed simultaneously in the base station and the terminal in the corresponding subframe, but is not limited to this, and the beam change may be performed to transmit and receive signals with the changed beam in subsequent subframes including subframe n+k. there is.

In step 1430, the base station 1402 may transmit a signal to the terminal 1401 using the changed beam, and the terminal 1401 may receive the signal using the changed beam.

In step 1430, the terminal 1401 can receive a signal with the changed beam. More specifically, the terminal 1401 can change the beam to the beam reported in step 1415 in subsequent subframes including subframe n+k.

FIG. 15 is a diagram illustrating a beam control method based on a beam control identifier included in a beam information reporting message according to another embodiment of the present specification.

Referring to FIG. 15, terminal 1501 can transmit and receive signals to and from the base station 1502.

In step 1510, the base station 1502 may transmit information requesting one of BSI and BRI to the terminal 1501, and the information may be transmitted to the terminal through DCI.

In step 1515, the terminal 1301 may transmit at least one of BSI and BRI to the base station 1302 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality. In an embodiment, the indicator may be turned off and transmitted to indicate beam change.

In step 1520, the terminal 1501 and the base station 1502 may not change at least one of the transmission beam and the reception beam because the identifier indicating whether to change the beam included in step 1515 is displayed as off. Additionally, depending on the embodiment, an additional beam change procedure may be performed by base station control.

In this way, the base station 1502 can report beam-related information to the terminal 1301 and may not perform beam changes based on the judgment of the terminal 1501.

Additionally, in an embodiment, the terminal transmits identification information indicating whether to change the beam to the base station, and may change the beam in response to the base station transmitting a confirmation signal based on this.

FIG. 16 is a diagram illustrating a method of controlling a beam through a confirmation message based on a beam control identifier included in a beam information reporting message according to an embodiment of the present specification.

Referring to FIG. 16, the terminal 1601 can transmit and receive signals with the base station 1602.

In step 1610, the base station 1602 may transmit information requesting one of BSI and BRI to the terminal 1601, and the information may be transmitted to the terminal through DCI.

In step 1615, the terminal 1601 may transmit at least one of BSI and BRI to the base station 1602 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality. Additionally, an identifier indicating whether to change the beam may be included and transmitted to the base station 1602 along with at least one of the BSI and BRI. In an embodiment, an indicator may be turned on and transmitted to indicate beam change.

In step 1620, the base station 1602 may transmit a signal including an acknowledgment corresponding to the beam change indicator to the terminal 1601 in subframe n. In an embodiment, if a response corresponding to the identification information transmitted in step 1615 is not transmitted from the base station 1602 or a negative response (NACK) is transmitted, beam change may not be performed in the operation below. In this way, the base station 1602 receives information requesting a beam change from the terminal, but may not perform the beam change by transmitting a NACK.

If an acknowledgment (ACK) has been previously transmitted in subframe n in step 1625, the base station 1602 may change the base station beam based on the information received in step 1615. More specifically, it is possible to transmit a signal using the changed beam starting from a subframe transmitted after a certain period of time (after k subframes in the embodiment) after transmitting the positive response. Additionally, in step 1630, the terminal 1601 may change the beam in subframe n+k based on the information transmitted in step 1615. In an embodiment, the beam change may be performed simultaneously in the base station and the terminal in the corresponding subframe, but is not limited to this, and the beam change may be performed to transmit and receive signals with the changed beam in subsequent subframes including subframe n+k. there is.

In step 1635, the base station 1602 may transmit a signal to the terminal 1601 based on the changed beam in subframe n+k. The value of k can be determined using the methods previously described.

FIG. 17 is a diagram illustrating a method of controlling a beam through a confirmation message based on a beam control identifier included in a beam information reporting message according to another embodiment of the present specification.

Referring to FIG. 17, the terminal 1701 can transmit and receive signals with the base station 1702.

In step 1710, the base station 1702 may transmit information requesting one of BSI and BRI to the terminal 1701, and the information may be transmitted to the terminal through DCI.

In step 1715, the terminal 1701 may transmit at least one of BSI and BRI to the base station 1702 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality. Additionally, an identifier indicating whether to change the beam may be included and transmitted to the base station 1702 along with at least one of the BSI and BRI. In an embodiment, the indicator may be turned off and transmitted to indicate beam change.

In step 1720, the base station 1702 may transmit a signal including an acknowledgment corresponding to the beam change indicator to the terminal 1701 in subframe n. In an embodiment, if a response corresponding to the identification information transmitted in step 1715 is not transmitted from the base station 1702, beam change may not be performed in the operation below. Additionally, the base station 1702 may perform beam change by transmitting NACK in response to the above information.

In step 1725, if an acknowledgment (ACK) was previously transmitted in subframe n, the base station 1702 and the terminal 1701 may not perform beam change. However, even in this case, beam change may be performed based on additional information transmitted by the base station in step 1720.

In the embodiments of FIGS. 12 to 17, the base station may determine beam change based on the received BSI/BRI information and transmit information indicating beam change to the terminal accordingly. In an embodiment, this operation may be performed regardless of whether the beam change identifier transmitted by the terminal is on/off.

In relation to the method of instructing beam change, the following operations of the base station and terminal are possible.

In an embodiment, when there are at least two beam-related reference signals, the beam change method described above with reference to FIGS. 12 to 17 may be performed only for beams corresponding to specific reference signals. In one embodiment, the above method can be applied to a periodic or cell-specific reference signal. In another embodiment, the above method may not be applied to aperiodic or UE-specific reference signals. Additionally, depending on the embodiment, the relevant reference signal for applying the method may be changed and applied.

Additionally, in addition to the beam change method proposed in the embodiment, other beam change methods may be operated simultaneously in the system. When different beam change methods are mixed, uncertainty about beam change may occur. In this case, such uncertainty can be eliminated by using OFF mode when controlling the base station or terminal beam.

Additionally, in an embodiment, when base station control and terminal control operate together, it may be considered to transmit the identification information about the beam change by turning it off depending on the environment in which base station control is suitable or the terminal control is suitable. More specifically, when base station control and terminal control are mixed in relation to beam change, uncertainty in beam change can be eliminated through priority. The following shows an example.

- Base station control takes priority, and when beam change is turned off in terminal control, terminal control may take priority over base station control.

- Base station control takes priority, and when beam change is turned on in terminal control, terminal control may take priority over base station control.

- Terminal control takes priority, and when beam change is turned off in base station control, base station control may take priority over terminal control.

- Terminal control takes priority, and when beam change is turned on in base station control, base station control may take priority over terminal control.

Additionally, in an embodiment, when the terminal reports beam information to the base station, the terminal selects the beam information to report based on the best BRSRP/BRRS-RP and transmits the information to the base station, and the base station selects the optimal beam information among the received beams. Beam change can be performed with a beam corresponding to BRSRP/BRRS-RP. When changing a beam to the optimal beam, there is a risk of frequent beam changes occurring even if there is no significant gain compared to the beam currently being used for the service. In order to control unnecessary beam changes, a threshold value may be applied to determine whether to perform a beam change based on this.

In an embodiment, when the number of beams that the terminal reports to the base station is one, the operation is possible with the following procedure.

If the BRSRP/BRRS-RP difference between the beam currently used by the terminal and the base station for signal transmission and reception and the optimal beam measured by the terminal is greater than a certain threshold, the optimal beam measured by the terminal can be reported. Additionally, if the BRSRP/BRRS-RP difference between the beam currently used by the terminal and the base station for signal transmission and reception and the optimal beam measured by the terminal is less than a certain threshold, the terminal can report information on the beam currently in use. Additionally, in an embodiment, when the beam change indicator is off, the terminal can also report beam information with BRSRP/BRRS-RP less than the threshold value to the base station. In addition, the terminal always reports the measured optimal beam, and the base station can make a decision based on the Threshold value when determining whether to apply a beam change.

When the terminal reports threshold-based beam information in the above manner, the base station knows that a beam that is better than the current service beam has been uploaded, so it changes the beam to that beam, thereby reducing the frequency of frequent reports of beams smaller than the threshold. Beam changes can be avoided.

Additionally, in the embodiment, if the number of beams that the terminal reports to the base station is two or more, the following procedure can be used.

When the terminal reports beam-related information to the base station, the base station/terminal operation for one beam is the same as the N=1 case (i.e., a beam to which a threshold is applied) and for the remaining N-1 beams. The Best BRSRP/BRRS-RP based beam can be selected among the remaining beams except for the one beam.

In addition, when the number of beams to which the threshold is applied is operated as one or more, base station/UE operation can select the optimal BRSRP/BRRS-RP reference beam among the beams that satisfy the threshold conditions, and for the remaining N-x beams, excluding the above beams. Among the remaining beams, you can select the Best BRSRP/BRRS-RP based beam.

In an embodiment, if the beam satisfying the threshold condition is smaller than x, it may be possible to select an optimal BRSRP/BRRS-RP based beam.

If the terminal reports optimal beam-related information to the base station in the above manner and the beam change indication is on, the beam change is performed to the optimal beam among the beams to which the threshold condition is applied to avoid frequent beam changes. Even in the case of terminal beam application, the beam can be changed to a beam corresponding to the base station beam.

FIG. 18 is a diagram illustrating a method of changing a beam based on a threshold value according to an embodiment of the present specification.

Referring to FIG. 18, the process of selecting a beam for a terminal to report to a base station in a reporting environment where a threshold condition is applied can be shown. For convenience of explanation, it is assumed that two BRS beams are measured and one beam is selected. Case 1 indicates that the beam is selected based on the optimal BRSRP when the Threshold is set to 0. On the other hand, if the Threshold value is set to 3 dB, beam 1 can be selected if the BRSRP increases by more than 3 dB compared to the BRSRP of beam 0 being used for the service.

FIG. 19 is a diagram illustrating a method of changing a beam based on a threshold value according to another embodiment of the present specification.

Referring to FIG. 19, the process of selecting a beam for a terminal to report to a base station in a reporting environment where a threshold condition is applied can be shown. In an embodiment, the threshold value may be 3dB, but this can be changed. In the embodiment, when the beam change indication information is ON, as shown in the first figure, after #0 beam is reported, if the threshold condition is not satisfied, #0 beam is reported even if #1 beam has a higher BRSRP, There may be no beam change at the base station. Also, in the second case, if #1 beam satisfies the threshold condition, #1 beam is reported, and from a certain point in time, the base station beam changes to #1 and the corresponding terminal beam, allowing signals to be transmitted and received between the base station and the terminal.

FIG. 20 is a diagram illustrating a method of changing a beam based on a threshold value according to another embodiment of the present specification.

Referring to FIG. 20, the process of selecting a beam for a terminal to report to a base station in a reporting environment where a threshold condition is applied can be shown. In an embodiment, the threshold value may be 3dB, but this can be changed. In an embodiment, when the beam change indication information is off, the beam change does not occur regardless of the beam information reported. At this time, the beam information can be reported by applying the threshold condition, or the optimal value currently measured by the terminal without applying the threshold condition is possible. Beam information can be reported to the base station.

In an embodiment, conditions related to the threshold value may be operated in the following manner.

- The base station lowers the threshold value to the terminal (i.e. RRC signaling or DCI or MAC-CE.)

- The terminal determines and transmits N beam information based on the optimal BRSRP or BRRS-RP.

- If the optimal beam among the reported beams satisfies a specific threshold condition, the base station and terminal perform automatic beam changes in subframe n+k based on subframe n at the reported time point.

Additionally, in an embodiment, when indicating a beam change, only beam changes for some channels may be indicated. More specifically, different beams can be applied by distinguishing uplink and downlink, and different beams can be applied to data channels and control channels in the same uplink or downlink. In addition, specific channels can be grouped and beam changes can be applied based on them.

Examples of such groupings may apply to one or more of the following:

- Method of instructing beam change for a specific physical (PHY) channel: When indicating a specific channel, beam change is applied only to that channel.

- Method of instructing beam change for UL channel / DL channel / all channels: to transmit instruction information for selective beam change, if designated as all UL-related channels, all DL-related channels, or all UL/DL channels, the corresponding channel Method of applying beam changes only to

- A method of grouping all PHY channels and signals into a specific channel bundle and instructing beam change for that group: Grouping PHY channels using a method other than UL/DL standards and changing beam for the group A method of transmitting and receiving by changing only the beams of channels or signals belonging to the group by giving instructions.

In addition, such grouping is not limited to the above example, but can be applied for selective beam change through various grouping and combination methods. In the selective beam change method, control of beam change for a specific group is possible by controlling at least one of the base station and the terminal.

The following method can be used to transmit information related to such selective beam change.

- Specific bit-based indication method included in BSI/BRI request DCI

- Instruction method applying different CRC masking when transmitting BSI/BRI request DCI

- Instruction method applying different scrambling sequences when transmitting BSI/BRI request DCI

- Semi-static indication method based on upper layer signals including RRC

- indication in some or all combinations of the above four methods

Indication bits Indicated Channels 00 PUCCH, PUSCH 01 PDCCH, PDSCH 10 SRS, PUCCH, PUSCH 11 CSI-RS, PDCCH, PDSCH

Table 8 shows an example of a specific bit-based indication method included in the BSI/BRI request DCI. When the terminal receives such information, if the indication bit is '00', the transmission and reception beams related to PUCCH and PUSCH can be changed based on the reported beam information. If the indication bit is '01', the transmission and reception beams related to the PUCCH and PUSCH can be changed based on the reported beam information. Transmission and reception beams related to PDCCH and PDSCH can be changed.

CRC mask Indicated Channels 0000000000000000 PUCCH, PUSCH 1111111111111111 PDCCH, PDSCH 0101010101010101 SRS, PUCCH, PUSCH 1010101010101010 CSI-RS, PDCCH, PDSCH

Table 9 is a table showing an example of an indication method applying different CRC masking when transmitting a BSI/BRI request DCI. The channel through which beam information is changed can be indicated through different CRC masking.

Scrambling seq . Indicated Channels a(i), i=0,… .,# of data symbol PUCCH, PUSCH b(i), i=0,… .,# of data symbol PDCCH, PDSCH c(i), i=0,… .,# of data symbol SRS, PUCCH, PUSCH d(i), i=0,… .,# of data symbol CSI-RS, PDCCH, PDSCH

Table 10 is a table showing an example of an indication method applying different scrambling sequences when transmitting a BSI/BRI request DCI. By applying different scrambling sequences, the channel through which beam information is changed can be indicated.

Indication bits Indicated UL Channels Indicated DL Channels 00 PUCCH PDCCH 01 PUSCH PDSCH 10 PUCCH, PUSCH PDCCH, PDSCH 11 SRS, PUCCH, PUSCH CSI-RS, PDCCH, PDSCH

Table 11 shows instructions for beam change in different channels of the uplink channel and downlink channel based on the same indication bit.

More specifically, an instruction to change an uplink channel beam may be transmitted to the terminal through UL DCI, and an instruction to change a downlink channel beam may be transmitted to the terminal through DL DCI. Additionally, depending on the embodiment, it may be transmitted semi-statically to the terminal through a higher layer signal such as RRC.

As such, the beam change procedure including the methods in Tables 8 to 11 may proceed as follows.

- Change the beam when the channels indicated by the base station and terminal control are different.

- Operate by distinguishing channels in which the base station can control beam changes and channels in which the terminal can control beam changes.

: As an example, instructions for selective beam change for the DL channel can be operated only under base station control, and instructions for selective beam change for the UL channel can be operated only under terminal control. It can be operated by dividing into specific groups rather than DL/UL standards. In the example of Table 11, as an example of simultaneous operation of UL/DL-based base station/terminal control, instructions for UL and DL are operated separately to limit instructions for selective beam change of the terminal to the UL channel, This shows an example of an operation that limits the instruction for selective beam change of the base station to the DL channel.

In addition, there are no restrictions on the channels that can be controlled by the base station / terminal for beam change, but it can be operated by giving priority to the control of the base station or terminal in beam change control for a specific channel. As an example of this, in the case of an indication of a selective beam change on the UL channel, the terminal control can be given priority, and in the case of an indication of a selective beam change on the DL channel, the base station control can be given priority.

Figure 21 is a diagram showing a selective beam change method according to an embodiment of the present specification.

Referring to FIG. 21, the terminal 2101 can transmit and receive signals with the base station 2102.

In step 2110, the base station 2102 may transmit information requesting one of BSI and BRI to the terminal 2101, and the information may be transmitted to the terminal through DCI. In an embodiment, at least one of information indicating whether a beam change is requested to the DCI and information indicating a group to which the changed beam will be applied may be included. In the embodiment, whether the beam change is requested is indicated as on, and indicates the group. The identifier may be displayed as 01 and transmitted. A more detailed method of indicating whether to request a beam change will be described later.

In step 2115, the terminal 2101 may transmit at least one of BSI and BRI to the base station 2102 through at least one of xPUCCH and xPUSCH in subframe n. In an embodiment, at least one of the xPUCCH and xPUSCH may be indicated through the DCI. In an embodiment, the reported beam information may include at least one beam information, and may be reported sequentially, starting from the beam with the best quality.

In step 2120, the base station 2102 determines that the beam change identifier in the DCI transmitted in step 2110 is on, and the corresponding channels are PDCCH and PDSCH based on Table 8, and subframe n+ based on the information received in step 1215. At k, the beam applied to PDCCH and PDSCH transmission can be changed. In another embodiment, based on the received beam information, the base station beams only if at least one of the BRSRP and BRRS-RP of the corresponding beam is better than the threshold value to control beam change compared to the beam currently in use. Changes can be made. The value of k can be determined using the methods previously described. To control the beam change, a threshold value may be determined by the method described in the above embodiment. In step 2125, the terminal 2101 changes the beam in subframe n+k based on the information transmitted in step 2115. can be performed. The beam change of the terminal 2101 can also determine whether to change the beam based on the Threshold value. In an embodiment, the beam change may be performed simultaneously in the base station and the terminal in the corresponding subframe, but is not limited to this, and the beam change may be performed to transmit and receive signals with the changed beam in subsequent subframes including subframe n+k. there is.

In step 2130, the base station 2102 may transmit a signal including the PDCCH and PDSCH to the terminal 2101 using the changed beam. Additionally, the terminal 2101 can receive signals including PDCCH and PDSCH from the base station 2102 through the changed beam.

In step 2130, the terminal 2101 can receive a signal with the changed beam, and more specifically, can perform a beam change to the beam reported in step 2115 in subsequent subframes including subframe n+k.

In addition, in the case of unindicated channels, signals can be transmitted and received by maintaining the existing beam.

Additionally, if there is a transmission error in information related to beam change throughout the embodiment, the operation may be performed as follows.

- When BSI/BRI request information sent by the base station is lost

In an embodiment, if a signal is not received from the terminal at the time the base station receives a report from the terminal according to the BSI/BRI request, the base station may retransmit the BSI/BRI request information to the terminal, and the request may be retransmitted. The point in time at which the corresponding BSI/BRI report is received is determined as subframe n, and beam changes can be performed based on this.

- When the BSI/BRI request is incorrectly reported (false alarm case)

If a BSI/BRI report that the base station did not request from the terminal is received, the base station may transmit a DCI including a BSI/BRI request before the beam change point (before k subframes in the embodiment). The terminal that has received the DCI may operate to ignore the previous message about beam change. In another embodiment, when beam change is unnecessary, the base station may transmit beam change request indication information to the DCI by setting it to off. Additionally, when a beam change is necessary, the beam change request indication information can be set to on and transmitted.

- When BSI/BRI reporting information sent by the terminal is lost

In an embodiment, if a report on the BSI/BRI request transmitted by the base station is not received by the base station at a preset time, the base station may retransmit the BSI/BRI request. If the BSI/BRI request is retransmitted, the time at which the BSI/BRI is reported is reset to subframe n based on the time of retransmission. Additionally, these error response cases can be similarly applied across automatic beam change methods.

Figure 22 is a diagram showing a terminal according to an embodiment of the present specification.

Referring to FIG. 22, the terminal 2200 of the embodiment includes a transmission/reception unit 2202, a storage unit 2204, and a control unit 2206.

The transceiver unit 2202 can transmit and receive signals to and from the base station.

The storage unit 2204 may store at least one of information related to the terminal 2200 and information transmitted and received through the transmitting and receiving unit 2202.

The control unit 2206 can control the operation of the terminal 2200 and can control the entire terminal to perform operations related to the terminal described in the above embodiment. The control unit 2206 may include at least one processor.

Figure 23 is a diagram showing a base station according to an embodiment of the present specification.

Referring to FIG. 23, the base station 2300 of the embodiment includes a transceiver 2302, a storage 2304, and a control unit 2306.

The transmitting and receiving unit 2302 can transmit and receive signals with the terminal and other network entities.

The storage unit 2304 may store at least one of information related to the base station 2300 and information transmitted and received through the transmitting and receiving unit 2302.

The control unit 2306 can control the operation of the base station 2300 and can control the entire base station to perform operations related to the base station described in the above embodiment. The control unit 2306 may include at least one processor.

Meanwhile, the specification and drawings disclose preferred embodiments of the present invention, and although specific terms are used, they are used in a general sense to easily explain the technical content of the present invention and to aid understanding of the present invention. It is not intended to limit the scope of the invention. In addition to the embodiments disclosed herein, it is obvious to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented.

Claims (20)

In a method performed by a terminal of a wireless communication system,
Receiving a reference signal for measurement of at least one beam from a base station;
Transmitting first information regarding the results of the measurement to the base station;
Receiving second information indicating a specific beam among the at least one beam from the base station in a first subframe;
determining a second subframe, which is a subframe several subframes after the first subframe, to which the specific beam will be applied, based on the second information; and
A method comprising communicating with the base station using the specific beam starting from the second subframe. According to claim 1,
The second information indicating the specific beam is included in downlink control information for scheduling an uplink signal,
The second subframe is the first timing of uplink signal transmission based on the uplink grant included in the downlink control information, and the second timing before reception of an acknowledgment according to the uplink signal. A method characterized in that it is determined by at least one of timing, or a third timing after receipt of the positive response according to the received positive response. According to claim 1,
The second information indicating the specific beam is included in downlink control information for scheduling a downlink signal,
The second subframe is a first timing of receiving a downlink signal based on a downlink grant included in the downlink control information, and a second timing before transmission of an acknowledgment according to the downlink signal. A method characterized in that it is determined by at least one of timing, or a third timing after transmission of the positive response according to the transmitted positive response. According to claim 1,
The second information indicating the specific beam is included in a medium access control (MAC) control element (CE),
The second subframe is characterized in that the timing is determined after transmission of an acknowledgment according to the MAC CE. According to claim 1,
The method further comprising receiving a value for determining the number of subframes from the base station through upper layer signaling or a downlink control signal. In a method performed by a base station of a wireless communication system,
Transmitting a reference signal for measurement of at least one beam to a terminal;
Receiving first information about the result of the measurement from the terminal;
Transmitting second information indicating a specific beam among the at least one beam to the terminal in a first subframe;
determining a second subframe, which is a subframe several subframes after the first subframe, to which the specific beam will be applied, based on the second information; and
A method comprising communicating with the terminal using the specific beam starting from the second subframe. According to clause 6,
The second information indicating the specific beam is included in downlink control information for scheduling an uplink signal,
The second subframe is the first timing of receiving an uplink signal based on the uplink grant included in the downlink control information, and the second timing before transmission of an acknowledgment according to the uplink signal. A method characterized in that it is determined by at least one of timing, or a third timing after transmission of the positive response according to the transmitted positive response. According to clause 6,
The second information representing the specific beam is included in downlink control information for scheduling a downlink signal,
The second subframe includes a first timing of downlink signal transmission based on a downlink grant included in the downlink control information, and a second timing before reception of an acknowledgment according to the downlink signal. , or a third timing after receiving the positive response according to the received positive response. According to clause 6,
The second information indicating the specific beam is included in a medium access control (MAC) control element (CE),
The second subframe is characterized in that the timing is determined after receiving an acknowledgment according to the MAC CE. According to clause 6,
The method further comprising transmitting a value for determining the number of subframes to the terminal through upper layer signaling or a downlink control signal. In the terminal of a wireless communication system,
Transmitter and receiver; and
It is connected to the transceiver, receives a reference signal for measurement of at least one beam from the base station, transmits first information about the result of the measurement to the base station, and transmits a specific signal from the at least one beam. Second information indicating a beam is received from the base station, the second information is received in a first subframe, and the second information is a subframe several subframes after the first subframe to which the specific beam is applied. 2 A terminal including a control unit that determines a subframe based on the second information and communicates with the base station using the specific beam starting from the second subframe. According to claim 11,
The second information indicating the specific beam is included in downlink control information for scheduling an uplink signal,
In the control unit,
The second subframe is the first timing of uplink signal transmission based on the uplink grant included in the downlink control information, and the second timing before reception of an acknowledgment according to the uplink signal. A terminal characterized in that it is determined by at least one of timing, or a third timing after reception of the positive response according to the received positive response. According to claim 11,
The second information indicating the specific beam is included in downlink control information for scheduling a downlink signal,
In the control unit,
The second subframe is a first timing of receiving a downlink signal based on a downlink grant included in the downlink control information, and a second timing before transmission of an acknowledgment according to the downlink signal. A terminal characterized in that it is determined by at least one of timing, or a third timing after transmission of the positive response according to the transmitted positive response. According to claim 11,
In the control unit,
The second information indicating the specific beam is included in a medium access control (MAC) control element (CE),
The second subframe is characterized in that the timing is determined after transmission of an acknowledgment according to the MAC CE. According to claim 11,
The control unit,
A terminal characterized in that it receives a value for determining the number of subframes from the base station through upper layer signaling or a downlink control signal. In the base station of a wireless communication system,
Transmitter and receiver; and
It is connected to the transceiver, transmits a reference signal for measurement of at least one beam to the terminal, receives first information about the result of the measurement from the terminal, and selects a specific signal from among the at least one beam. Second information indicating a beam is transmitted to the terminal, the second information is transmitted in a first subframe, and the second information is a subframe several subframes after the first subframe to which the specific beam is applied. A base station comprising a control unit that determines 2 subframes based on the second information and communicates with the terminal using the specific beam starting from the second subframe. According to claim 16,
The second information indicating the specific beam is included in downlink control information for scheduling an uplink signal,
In the control unit,
The second subframe is the first timing of receiving an uplink signal based on the uplink grant included in the downlink control information, and the second timing before transmission of an acknowledgment according to the uplink signal. A base station characterized in that it is determined by at least one of timing, or a third timing after transmission of the positive response according to the transmitted positive response. According to claim 16,
The second information representing the specific beam is included in downlink control information for scheduling a downlink signal,
In the control unit,
The second subframe includes a first timing of downlink signal transmission based on a downlink grant included in the downlink control information, and a second timing before reception of an acknowledgment according to the downlink signal. , or a third timing after receiving the positive response according to the received positive response. According to claim 16,
In the control unit,
The second information indicating the specific beam is included in a medium access control (MAC) control element (CE),
The second subframe is a base station characterized in that the timing is determined after receiving an acknowledgment according to the MAC CE. According to claim 16,
The control unit,
A base station characterized in that it transmits a value for determining the number of subframes to the terminal through upper layer signaling or a downlink control signal.

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