KR102229378B1 - Data transmission method based on multi beamforming for ultra-reliable and low latency communication in a wireless communication system and apparatus thereof - Google Patents

Abstract

A data transmission method based on multi-beamforming for ultra-low-latency, high-reliability communication in a wireless communication system and an apparatus therefor are provided. In a wireless communication system, a data transmission method by a terminal includes receiving control information including information on a plurality of beams from a base station, each of which is mapped to the plurality of beams based on the information on the plurality of beams. Configuring a plurality of PUSCHs-Here, the same uplink data is mapped to the plurality of PUSCHs, and may include transmitting the configured plurality of PUSCHs to the base station.

Description

Multi-beamforming-based data transmission method for ultra-low-latency, high-reliability communication in a wireless communication system, and an apparatus therefor {DATA TRANSMISSION METHOD BASED ON MULTI BEAMFORMING FOR ULTRA-RELIABLE AND LOW LATENCY COMMUNICATION IN A WIRELESS COMMUNICATION SYSTEM AND APPARATUS THEREOF}

The present invention relates to a method and apparatus for transmitting data in a wireless communication system, and more particularly, to a method and apparatus for transmitting data quickly and stably using a plurality of beams.

For communication in various application fields corresponding to a 5G URLLC (Ultra-Reliable and Low Latency Communication) communication scenario, data needs to be transmitted quickly and stably. However, if the terminal moves in a direction in which the channel is deteriorating in a fast moving environment, an error may occur when the base station sets and transmits the transmission format based on the channel quality indicator (CQI) fed back to the base station by the corresponding terminal. , This may result in a situation in which the data needs to be retransmitted.

In the case of general data transmission, even if the data is retransmitted, there is no problem, but in the case of transmitting the URLLC data, a problem of increasing latency may occur when the retransmission occurs.

An object of the present invention is to provide a method and apparatus for transmitting data based on multi-beamforming that can communicate with a stable and short delay.

Another technical problem of the present invention is to provide a multi-beamforming-based data transmission method and apparatus capable of minimizing a time delay that occurs when data is retransmitted.

According to an aspect of the present invention, a method of transmitting data by a terminal in a wireless communication system includes receiving control information including information on a plurality of beams from a base station, based on the information on the plurality of beams. Configuring a plurality of PUSCHs each mapped to the plurality of beams-Here, the same uplink data is mapped to the plurality of PUSCHs, and transmitting the configured plurality of PUSCHs to the base station.

According to one side, the control information may include beamforming information on the plurality of beams.

According to another aspect, prior to the receiving of the control information, a step of receiving a Radio Resource Control (RRC) message including at least one of a number of beams and a beam transmission method from the base station may be further included.

According to another aspect, before the step of receiving the control information, the step of transmitting a reference signal for measuring a channel state to the base station, the downlink control information may be configured based on the reference signal. .

According to another aspect of the present invention, a data transmission method by a base station in a wireless communication system includes determining a plurality of beams for transmission of downlink data, and transmitting control information including information on the determined plurality of beams to a terminal. Transmitting, configuring a plurality of PDSCHs each mapped to the plurality of beams based on the determined information on the plurality of beams-Here, the same downlink data is mapped to the plurality of PDSCHs, and the configured plurality of It may include transmitting the PDSCH to the terminal.

On one side, the control information may include beamforming information on the plurality of beams.

According to another aspect, prior to the determining of the plurality of beams, the step of receiving a reference signal for measuring a channel state from the terminal may be further included, and the plurality of beams may be determined based on the channel state.

According to another aspect, before the step of determining the plurality of beams, it may further include transmitting an RRC message including at least one of the number of beams and a beam transmission method to the terminal.

According to the present invention, when data corresponds to an ultra-reliable low latency communication (URLLC), a transmitter transmits a plurality of identical data based on multiple beamforming, so that data can be transmitted with a stable and short delay.

In addition, according to the present invention, since a plurality of identical data can be transmitted through multiple beamforming and combined during decoding, a case in which data retransmission is required can be minimized.

1 is a conceptual diagram showing a wireless communication system according to an embodiment of the present invention.
2 is an exemplary diagram showing an NR system to which a data transmission method according to an embodiment of the present invention can be applied.
3 is a diagram illustrating a slot structure used in a data transmission method according to an embodiment of the present invention.
4 is a diagram for explaining a mini slot used in a data transmission method according to an embodiment of the present invention.
5 is a diagram for explaining multi-beamforming applied to the present invention.
6 is a flowchart illustrating a method of transmitting downlink data according to an embodiment of the present invention.
7 is a flowchart illustrating a method of transmitting uplink data according to an embodiment of the present invention.
8 is a block diagram showing a wireless communication system in which an embodiment of the present invention is implemented.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements.

In the present specification, terms such as "first", "second", "A", and "B" may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Also, the term "and/or" includes a combination of a plurality of related stated items or any of a plurality of related stated items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance.

Unless otherwise defined, terms used in the present specification have the same meaning as commonly understood by those of ordinary skill in the art, including technical or scientific terms, to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present specification. Does not.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram showing a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 1, a wireless communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, and 130-3. , 130-4, 130-5, 130-6).

Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes is a communication protocol based on Code Division Multiple Access (CDMA), a communication protocol based on Wideband CDMA (WCDMA), a communication protocol based on Time Division Multiple Access (TDMA), and frequency division multiple access (FDMA). Access) based communication protocol, OFDM(Orthogonal Frequency Division Multiplexing) based communication protocol, OFDMA(Orthogonal Frequency Division Multiple Access) based communication protocol, SC(Single Carrier)-FDMA based communication protocol, NOMA(Non-Orthogonal Multiple) Access)-based communication protocol and SDMA (space division multiple access)-based communication protocol can be supported.

The wireless communication system 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2 and a plurality of user equipments 130-1, 130-2, 130-3, 130-4, 130-5, 130-6).

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong within the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong within the coverage of the third base station 110-3. . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong within the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, and a next generation node B. B, gNB), Base Transceiver Station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), DU (Digital Unit), CDU (Cloud Digital Unit), RRH (Radio Remote Head), RU (Radio Unit), TP (Transmission Point), TRP (transmission and reception point), a relay node (relay node), etc. I can. Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is a terminal, an access terminal, a mobile terminal, It may be referred to as a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, and the like.

A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) each of which may support a cellular (cellular) communication (for ^{example, 3GPP (3 rd generation partnership project} ) standard, LTE (long term evolution), LTE-a (advanced), NR (new Radio) defined by, and so on). Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information can be exchanged with each other through a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is transmitted to the core network. Can be transferred to.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support OFDMA-based downlink transmission, and SC-FDMA-based uplink ) Can support transmission. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits Multiple Input Multiple Output (MIMO) (e.g., Single User (SU)-MIMO, Multi User (MU)-MIMO, Massive MIMO, etc.), Coordinated Multipoint (CoMP) transmission, carrier aggregation transmission, transmission in an unlicensed band, device to device, D2D) communication (or ProSe (proximity services), etc. can be supported. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6) Operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and/or base station (110-1, 110-2, 110-3, 120-1, 120-2) Can perform operations supported by ).

For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 can transmit a signal to the fourth terminal 130-4 by the SU-MIMO scheme. A signal may be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO method, and the fourth terminal 130-4 And each of the fifth terminal 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 has terminals 130-1, 130-2, 130-3, 130-4, and 130-5, 130-6) and the CA method can transmit and receive signals.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 coordinates D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5 (coordination), and each of the fourth terminal 130-4 and the fifth terminal 130-5 is D2D communication by coordination of the second base station 110-2 and the third base station 110-3 You can do it.

Hereinafter, even when a method performed in the first communication node among communication nodes (eg, transmission or reception of a signal) is described, the second communication node corresponding thereto is a method corresponding to the method performed in the first communication node. A method (eg, reception or transmission of a signal) can be performed. That is, when the operation of the terminal is described, the corresponding base station may perform the operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, a terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

In addition, hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of the base station.

Recently, as the spread of smartphones and Internet of Things (IoT) terminals is rapidly spreading, the amount of information exchanged through a communication network is increasing. Accordingly, in the next-generation wireless access technology, an environment that provides faster service to more users than an existing communication system (or an existing radio access technology) (e.g., enhanced mobile broadband communication) )) needs to be considered. To this end, a design of a communication system considering Machine Type Communication (MTC), which provides a service by connecting a plurality of devices and objects, is being discussed. In addition, a design diagram of a communication system (e.g., URLLC (Ultra-Reliable and Low Latency Communication)) that considers service and/or terminal sensitive to communication reliability and/or latency. It is being discussed.

Hereinafter, in this specification, for convenience of description, the next-generation radio access technology is referred to as New RAT (Radio Access Technology), and the wireless communication system to which the New RAT is applied is referred to as NR (New Radio) system.

2 is an exemplary diagram showing an NR system to which a data transmission method according to an embodiment of the present invention can be applied.

2, the NG-RAN (Next Generation-Radio Access Network) is an NG-RA user plane (new AS sublayer/PDCP/RLC/MAC/PHY) and a control plane (RRC) protocol for UE (User Equipment). It consists of gNBs that provide termination. Here, NG-C represents a control plane interface used for an NG2 reference point between NG-RAN and 5 GC (5 Generation Core). NG-U represents the user plane interface used for the NG3 reference point between NG-RAN and 5GC.

The gNBs are interconnected through the Xn interface and connected to the 5GC through the NG interface. More specifically, the gNB is connected to an Access and Mobility Management Function (AMF) through an NG-C interface, and is connected to a User Plane Function (UPF) through an NG-U interface.

In the NR system of FIG. 2, a number of numerologies may be supported. Here, the neurology may be defined by subcarrier spacing and cyclic prefix (CP) overhead. In this case, the plurality of subcarrier intervals can be derived by scaling the basic subcarrier interval by an integer. Further, even if it is assumed that a very low subcarrier spacing is not used at a very high carrier frequency, the neurology to be used can be selected independently of the frequency band.

In addition, in the NR system, various frame structures according to a number of neurology may be supported. Hereinafter, an OFDM neurology and a frame structure used in a data transmission method according to an embodiment of the present invention will be described with reference to FIG. 3.

3 is a diagram illustrating a slot structure used in a data transmission method according to an embodiment of the present invention.

The Time Division Duplexing (TDD) structure considered in the NR system is a structure that processes both uplink (UL) and downlink (DL) in one slot (or subframe). This is to minimize the latency of data transmission in the TDD system, and may be referred to as a self-contained structure or a self-contained slot.

Referring to FIG. 3, one slot may consist of 14 OFDM symbols. In FIG. 3, region 310 represents a downlink control region, and region 320 represents an uplink control region. Regions other than regions 310 and 320 (ie, regions without a separate indication) may be used for transmission of downlink data or uplink data. That is, uplink control information and downlink control information may be transmitted in one slot. On the other hand, in the case of data, uplink data or downlink data may be transmitted in one slot.

When the structure shown in FIG. 3 is used, downlink transmission and uplink transmission are sequentially performed within one slot, and downlink data transmission and uplink ACK/NACK reception may be performed. Accordingly, when an error in data transmission occurs, the time required to retransmit data may be reduced. Through this, delay related to data transmission can be minimized.

In the slot structure as shown in FIG. 3, a time gap is required for a process of switching from a transmission mode to a reception mode by a base station and/or a terminal or a process of switching from a reception mode to a transmission mode. do. Regarding the time difference, when uplink transmission is performed after downlink transmission in the slot, some OFDM symbol(s) may be set as a guard period (GP).

4 is a diagram for explaining a mini slot used in a data transmission method according to an embodiment of the present invention.

According to an embodiment of the present invention, in addition to slot-based scheduling, mini-slot-based scheduling may be supported for efficient support for URLLC. A mini-slot is a minimum scheduling unit by a base station, and may consist of 2, 4, or 7 OFDM symbols, for example.

The mini-slot may start in any OFDM symbol in the slot as shown in FIG. 4. In FIG. 4, two mini-slots having different lengths (the number of OFDM symbols) in one slot are shown, but this is for illustration only, and when a plurality of mini-slots are included in one slot, each mini-slot The number of OFDM symbols constituting a may be the same.

In the NR system, for communication in various application fields corresponding to V2X (Vehicle to Everything) and URLLC scenarios, the transmitted data needs to be transmitted stably and quickly with almost no errors. In particular, when the terminal moves in a direction in which the channel is deteriorating in a fast moving environment, an error may occur when the base station sets the transmission format and transmits data based on the CQI fed back to the base station by the corresponding terminal, and this may cause retransmission There is a high likelihood of a situation where you have to do something. In the case of transmitting general data such as eMBB (enhanced 　 mobile 　 broad band) data, there is no big problem even if retransmission occurs, but in the case of URLLC data, if retransmission occurs, a problem may occur due to latency due to retransmission. In the V2X scenario, the URLLC scenario, etc., in most cases, the amount of transmitted user data is not large, so using a little additional resource may not be a heavy burden. Rather, it may be worse if an error occurs and the delay increases due to retransmission. Therefore, in the present invention, data can be transmitted in the following manner. The data transmission method according to the present invention can be applied to various scenarios of URLLC as well as vehicle communication such as V2X.

5 is a diagram for explaining multi-beamforming applied to the present invention.

Beamforming refers to a signal processing technology used in an antenna array to transmit or receive a directional signal. In the present invention, beamforming includes analog beamforming, digital beamforming, and hybrid beamforming.

In a millimeter wave (mmWave, mmW) communication system such as an NR system, as the wavelength of a signal is shorter than that of a conventional communication system, multiple (or multiple) antennas can be installed in the same area. For example, in the 30GHz band, the wavelength is about 1cm, and if antennas are installed at 0.5 lambda intervals on a 5cm x 5cm panel according to a 2-dimension arrangement, a total of 100 Antenna elements may be installed. Accordingly, in the mmW communication system, a method of increasing coverage or increasing throughput by increasing a beamforming gain using a plurality of antenna elements may be considered. In this case, when a TXRU (Transceiver Unit) is installed to enable transmission power and phase adjustment for each antenna element, independent beamforming for each frequency resource is possible. However, the method of installing TXRUs on all antenna elements may be less effective in terms of price. Accordingly, a method of mapping a plurality of antenna elements to one TXRU and controlling the direction of a beam using an analog phase shifter may be used. Since this analog beamforming method can generate only one beam direction in all bands, a frequency selective beam operation cannot be performed.

In the case of digital beamforming, each antenna element may have a dedicated RF chain including RF processing and ADC/DAC. The signal processed by each antenna element can be independently controlled in phase and amplitude to optimize channel capacity. The number of RF chains may be equal to the number of antenna elements. Therefore, the digital beamforming method provides very high performance, but requires high cost, implementation complexity, and high energy consumption.

Accordingly, hybrid beamforming having B TXRUs less than Q antenna elements, which is a combination of digital beamforming and analog beamforming, may be considered. In this case, although there is a difference according to the connection method of the B TXRUs and Q antenna elements, the directions of beams capable of transmitting signals at the same time may be limited to B or less.

The transmitter may transmit data to the receiver using at least one of these beamforming methods. In this case, the conventional beamforming method transmits one data using one beam. Therefore, when an error occurs in the data transmitted to the receiver, the transmitter must retransmit the data. In the case of transmitting data that does not need to be transmitted quickly, such as eMBB data, this conventional beamforming method does not have any problem even if retransmission occurs due to an error, but when transmitting data that needs to be transmitted stably and quickly, such as URLLC data. Can be a problem. Accordingly, in the present invention, when transmitting URLLC data, a beam can be managed in a different manner than when transmitting eMBB data.

For example, as shown in FIG. 5, when the base station 500 transmits data to the terminal 510, rather than transmitting data using only one optimal beam (first beam), multiple beams (second beam) 1 to 3 beams) can be used to transmit data. In addition, when an error occurs in the data received through the first beam, the terminal 510 does not request the base station 500 to retransmit the data, but stably transmits the same data through the second beam and/or the third beam. Receiving it by using the device can prevent the delay due to retransmission. That is, when an error occurs in data transmitted to a beam (first beam) optimally selected by the base station 500, the terminal 510 transmits data transmitted to several different beams (second beam and third beam). Can be decoded. In this case, the terminal 510 may combine and decode the same data transmitted by multiple beams (first to third beams) as necessary. In this case, a beam diversity effect can be obtained in a situation in which the channel state is poor.

This method can be applied in both cases of codebook-based beamforming and non-codebook-based beamforming. Here, codebook-based beamforming refers to a beamforming method in which precoding is pre-determined in a codebook, and beamforming is not precoding based on a codebook, and beamforming is applied by reflecting channel state information. It means the way to do it.

Hereinafter, a method for transmitting data based on multiple beamforming according to the present invention will be described in more detail with reference to FIGS. 6 and 7.

6 is a flowchart illustrating a method of transmitting downlink data according to an embodiment of the present invention.

Referring to FIG. 6, when a reference signal is received from a base station (S610), the terminal may measure a current channel state based on this (S620). Here, the reference signal may be, for example, a Channel State Indicator-Reference Signal (CSI-RS), a Synchronization Signal Block (SSB), or the like.

When a channel status report is received from the terminal (S630), the base station may select a plurality of beams (optimal beam and at least one candidate beam) for downlink data transmission based on this (S640). Here, the at least one candidate beam may be a beam corresponding to a suboptimal. In addition, the channel status report may include a channel quality indicator (CQI), a rank indication (RI), a precoding matrix indicator (PMI), and the like. CQI may be defined as feedback information on downlink channel quality information measured by the UE. RI may be defined as feedback information on downlink rank information measured by the terminal. PMI may be defined as feedback information on downlink precoding matrix information measured by the UE. When the base station instructs the terminal to apply codebook-based beamforming in advance, the terminal may transmit an index of precoding that improves the channel state to the base station.

When the base station selects a plurality of beams, the number of beams to be selected may be indicated to the terminal through higher layer signaling such as a Radio Resource Control (RRC) message in advance. For this, as an example, the RRC message may include information such as the number of beams and a multi-beam transmission method. Here, the information on the multi-beam transmission method may include codebook-based or non-codebook-based, frequency division multiplexing (FDM), time division multiplexing (TDM), and whether or not FDM/TDM is applied.

When it is determined to transmit downlink data based on multiple beamforming, the base station may transmit downlink control information (DCI) including information on a plurality of beams to the terminal (S650). In the existing DCI format, only information on using one beam may be included. Therefore, in the present invention, in order to inform the terminal that one downlink data is to be transmitted through multiple beams, a new DCI format including information on multiple beams can be used. When the downlink control information of the new DCI format is received, the terminal can know that the base station will transmit the same downlink data several times through multiple beamforming.

Meanwhile, the base station may configure a plurality of PDSCHs each mapped to a plurality of beams based on information on the plurality of beams. In addition, the configured plurality of PDSCHs may be transmitted to the terminal based on multi-beamforming. Here, the same downlink data may be mapped to the plurality of PDSCHs. 6 illustrates a case where the base station transmits the same downlink data twice as an example. In this case, the base station may transmit the first PDSCH through the first beam (S660) and simultaneously transmit the second PDSCH through the second beam (S670). In this case, the UE decodes the first PDSCH transmitted through the first beam (optimal beam) from the base station (S680), and when successfully received, the second PDSCH transmitted through the next beam (second beam) is decoded. I can't. That is, when a plurality of PDSCHs are received through multi-beamforming, the UE may ignore the remaining PDSCHs without decoding if any one of the plurality of PDSCHs is successfully received.

If an error exists as a result of decoding the first PDSCH transmitted through the first beam, the UE may determine whether downlink data has been successfully received by decoding the second PDSCH transmitted through the second beam. However, if an error occurs in the second PDSCH as well, the data transmitted through the first PDSCH and the data transmitted through the second PDSCH are the same, so that the terminal receives the data received through the first beam and the data received through the second beam. By combining (combining) it can be determined whether the data has been successfully received. Through this, a beam diversity effect can be obtained, and data retransmission can be prevented.

Meanwhile, when codebook-based beamforming is used, the DCI may include precoding information applied to an optimal beam and subsequent beams (candidate beams). By notifying the terminal of this information in advance, the terminal can receive the multiple beams more quickly.

When non-codebook-based beamforming is used, precoding information is not separately notified to the terminal, but it may be helpful for DCI to receive multiple beams so that the terminal can receive multiple beams more quickly. Information that can be included may be included.

7 is a flowchart illustrating a method of transmitting uplink data according to an embodiment of the present invention.

The uplink data transmission procedure is similar to the downlink data transmission procedure of FIG. 6, but differs in that the terminal transmits a reference signal so that the base station can measure channel information.

Specifically, referring to FIG. 7, when a reference signal is received from the terminal (S710), the base station measures a current channel state based on this, and a plurality of beams (optimum beam and at least One candidate beam) may be selected (S720). Here, the reference signal may be, for example, a sounding reference signal (SRS).

When the base station selects a plurality of beams, the number of beams to be selected may be indicated to the terminal through higher layer signaling such as an RRC message in advance. In this case, the RRC message may include information such as the number of beams and a multi-beam transmission method. Here, the information on the multi-beam transmission method may include codebook-based or non-codebook-based, FDM, TDM, or FDM/TDM application.

When codebook-based beamforming is used, the DCI of the new format may include precoding information applied to the optimal beam and subsequent beams (candidate beams). When non-codebook-based beamforming is used, information that may be helpful for multi-beam reception may be included in the DCI of the new format.

When the use of multi-beamforming is determined by the base station when receiving uplink data, the base station may transmit downlink control information including information on a plurality of beams to the terminal (S730). In this case, the DCI may be transmitted in a new DCI format including information on a plurality of beams. When the downlink control information of the new DCI format is received, the terminal may transmit the same uplink data multiple times through multiple beamforming.

When the DCI is received, the UE may configure a plurality of PUSCHs each mapped to a plurality of beams based on information on a plurality of beams in the DCI. In addition, the plurality of PUSCHs may be transmitted to the base station based on multi-beamforming. Here, the same downlink data may be mapped to the plurality of PUSCHs. For example, as shown in FIG. 7, when the terminal transmits the same uplink data twice, the terminal may transmit the first PUSCH through the first beam (S740) and simultaneously transmit the second PUSCH through the second beam. (S750).

When the first PUSCH is received through the first beam (optimal beam) and the second PUSCH is received through the second beam, the base station may sequentially decode it (S760). If the first PUSCH is successfully received, the base station may not decode the second PDSCH. That is, when a plurality of PUSCHs are received through multi-beamforming, the base station may not decode the remaining PUSCHs if only one of the plurality of PUSCHs is successfully received.

However, if an error exists as a result of decoding the first PUSCH, the base station may determine whether the uplink data has been successfully received by decoding the second PDSCH. However, if an error occurs in the second PUSCH as well, it may be determined whether the data has been successfully received by combining the data received through the first PUSCH and the data received through the second PUSCH.

8 is a block diagram showing a wireless communication system in which an embodiment of the present invention is implemented.

Referring to FIG. 8, the terminal 800 includes a memory 805, a processor 810, and a radio frequency (RF) unit 815. The memory 805 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 815 is connected to the processor 810 and transmits and/or receives a radio signal. For example, the RF unit 815 may receive a downlink signal such as a CSI-RS, SSB, RRC message, DCI, PDSCH, etc. published herein from the base station 850. In addition, the RF unit 815 may transmit an uplink signal such as SRS and PUSCH posted in this specification to the base station 750.

The processor 810 implements the functions, processes, and/or methods of the terminal proposed in this specification. Specifically, the processor 810 performs the operation of the terminal illustrated in FIGS. 6 and 7. For example, the processor 810 may configure a plurality of PUSCHs each mapped to a plurality of beams with one uplink data according to an embodiment of the present invention. In all embodiments of the present specification, the operation of the terminal 800 may be implemented by the processor 810.

The memory 805 may store control information and setting information according to the present specification, and provide the control information and setting information to the processor 810 according to a request of the processor 810.

The base station 850 includes a processor 855, a memory 860, and a radio frequency (RF) unit 865. The memory 860 is connected to the processor 855 and stores various information for driving the processor 855. The RF unit 785 is connected to the processor 855 and transmits and/or receives a radio signal. The processor 855 implements the function, process, and/or method of the base station proposed in this specification. In the above-described embodiment, the operation of the base station may be implemented by the processor 855. The processor 855 generates the RRC message and downlink control information posted in this specification, determines whether to apply multi-beamforming according to the channel state, and uses one downlink data to each of the plurality of beams based on this. A plurality of PDSCHs to be mapped may be configured.

The processor may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processing device. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and/or other storage device. The RF unit may include a baseband circuit for processing a radio signal. When the embodiment of the present invention is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) that performs the above-described functions. The module may be stored in a memory and executed by a processor. The memory may be inside or outside the processor, and may be connected to the processor through various well-known means.

In the exemplary system described above, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with the steps described above. I can. In addition, those skilled in the art will appreciate that the steps shown in the flowchart are not exclusive, other steps may be included, or one or more steps in the flowchart may be deleted without affecting the scope of the present invention.

Claims (9)

In the data transmission method by the terminal in a wireless communication system,
Receiving a Radio Resource Control (RRC) message from a base station;
Receiving downlink control information for uplink transmission from the base station; And
Transmitting the same data to the base station using the plurality of beams based on information on a plurality of beams included in the downlink control information
Including,
The plurality of beams include an optimal beam and a candidate beam corresponding to at least one suboptimal,
The downlink control information includes precoding information applied to each of the plurality of beams. delete The method of claim 1,
The RRC message,
A data transmission method comprising information on at least one of the number of beams and a transmission method of each beam. The method of claim 1,
Before the step of receiving the downlink control information,
Further comprising the step of transmitting a reference signal for measuring the channel state to the base station,
The downlink control information, characterized in that configured based on the reference signal, data transmission method. In a method for a base station to receive data in a wireless communication system,
Transmitting a Radio Resource Control (RRC) message to the terminal;
Determining a plurality of beams for transmission of uplink data based on a reference signal received from the terminal;
Transmitting downlink control information including information on the determined plurality of beams to the terminal; And
Receiving the same data transmitted by the plurality of beams from the terminal
Including, wherein the plurality of beams include an optimal beam and a candidate beam corresponding to at least one suboptimal,
The downlink control information includes precoding information applied to each of the plurality of beams. The method of claim 5,
The RRC message,
A method of receiving data, comprising information on at least one of the number of beams and a transmission method of each beam. The method of claim 5,
After the receiving step,
When an error occurs in the data received through the first beam among the plurality of beams, the step of performing decoding by combining the data received through the first beam and the data received through the second beam among the plurality of beams. It characterized in that it comprises, data receiving method. delete The method of claim 5,
After the receiving step,
And ignoring data transmitted through a second beam among the plurality of beams when the data transmitted through the first beam among the plurality of beams is successfully received.

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