WO2021029595A1 - Data transmission method for ultra-low latency and highly-reliable communication in wireless communication system, and apparatus therefor - Google Patents

Abstract

Provided are a repetitive transmission method for ultra-low latency and highly-reliable communication in a wireless communication system, and an apparatus therefor. A method for transmitting data by a terminal according to an embodiment of the present invention comprises the steps of: receiving information on the number of times of repetitive transmission of a physical uplink shared channel (PUSCH) from a base station; receiving, from the base station, information on frequency hopping applied to the repetitive transmission of the PUSCH; configuring the repetitive transmission of the PUSCH; determining a frequency resource for the repetitive transmission of the PUSCH on the basis of the information on the frequency hopping; and performing the repetitive transmission of the PUSCH.

Description

Data transmission method and apparatus therefor for ultra-low-latency, high-reliability communication in wireless communication system

The present invention relates to a wireless communication system, and more particularly, to a data transmission method and apparatus for ultra-low latency high reliability communication.

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, in a case in which the terminal moves in a direction in which the channel is deteriorating in an environment in which the terminal moves rapidly, an error may occur in data, and thus, a situation in which the corresponding data must be retransmitted may occur.

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

An object of the present invention is to provide a method for repeatedly transmitting data with a stable and short delay.

Another technical problem of the present invention is to provide an apparatus for transmitting used data with a stable and short delay.

Another technical problem of the present invention is to provide a method of transmitting data based on a code blockgroup (CBG) in a scenario such as URLLC in which the amount of data is relatively small and data must be transmitted with a stable and short delay.

Another technical problem of the present invention is to provide an apparatus for transmitting data based on CBG in a scenario such as URLLC in which the amount of data is relatively small and data must be transmitted with a stable and short delay.

According to an aspect of the present invention, a method of transmitting data by a terminal in a wireless communication system includes downlink control information including information on the number of repetitive transmissions for uplink data from a base station and information on frequency hopping. ) Receiving, configuring a plurality of physical uplink shared channels (PUSCHs) corresponding to the number of repetitive transmissions-wherein the uplink data is identically mapped to the plurality of PUSCHs, and information on the frequency hopping Determining a frequency resource for transmission of the plurality of PUSCHs based on, wherein the frequency hopping range may be changed according to the size of a bandwidth part activated for transmission of the uplink data. have.

According to one side, the downlink control information further includes information on a length of a mini-slot used for repetitive transmission of the uplink data, and the plurality of PUSCHs are transmitted in units of the mini-slot. I can.

According to another aspect, the frequency resource may be a frequency resource corresponding to both ends of the activated bandwidth portion.

According to another aspect, the step of transmitting channel quality information to the base station prior to the receiving step may be further included, and the frequency hopping information may be determined based on the channel quality information.

According to another aspect, the information on the frequency hopping may include information on whether to apply the frequency hopping and information on a frequency hopping pattern.

According to another aspect, before the receiving step, further comprising the step of receiving information on a default (default) repetition transmission number for uplink transmission from the base station, wherein the downlink control information is the basic repetition transmission number And information on a difference value between the actual number of repeated transmissions of the uplink data.

According to another aspect of the present invention, a method for receiving data by a base station in a wireless communication system includes determining whether to apply frequency hopping to uplink data of the terminal based on channel quality information received from the terminal, the Transmitting downlink control information including information on the number of repetitive transmissions for the uplink data and information on the frequency hopping to a terminal, and the repetition through a frequency resource determined based on the information on the frequency hopping And receiving a plurality of PUSCHs corresponding to the number of transmissions from the terminal, wherein the uplink data is identically mapped to the plurality of PUSCHs, and the frequency hopping range is the terminal for transmission of the uplink data. It can be changed according to the size of the active bandwidth portion.

According to another aspect of the present invention, a method of transmitting data by a base station in a wireless communication system includes transmitting a plurality of physical downlink shared channels (PDSCHs) to which first data is identically mapped to a terminal, the plurality of data from the terminal. It may include receiving a feedback on the PDSCH of and determining the number of repetitive transmissions of the second data based on the feedback.

According to one side, before the transmitting step, the step of transmitting a Radio Resource Control (RRC) message including information on at least one of a maximum number of repetitive transmissions and a basic repetition number of downlink data to the terminal is further performed. And the plurality of PDSCHs may be configured according to the maximum number of repetitive transmissions or the basic number of repetition transmissions.

According to another aspect, the feedback includes ACK or NACK for each of the plurality of PDSCHs, and the number of repetitive transmissions for the second data is based on at least one of the number of ACKs and the number of NACKs included in the feedback. Can be determined.

According to another aspect, in the determining step, when the number of ACKs or NACKs included in the feedback is greater than or equal to a reference value, or the ratio between ACK and NACK included in the feedback is greater than or equal to a reference rate, the number of repetitive transmissions for the second data It may include the step of changing.

According to another aspect, the number of repetitive transmissions of the second data may be changed when a channel environment when transmitting the second data corresponds to a channel environment when transmitting the first data.

According to another aspect, after the determining step, it may further include transmitting downlink control information including information on the number of repetitive transmissions of the second data to the terminal.

According to another aspect, the downlink control information may include information on a difference value between the number of repeated transmissions for the first data and the number of repeated transmissions for the second data.

According to another aspect of the present invention, a method of transmitting data by a terminal in a wireless communication system comprises the steps of constructing a plurality of physical uplink shared channels (PUSCHs) to which first data is identically mapped and transmitting them to a base station, from the base station to the base station. Receiving feedback for a plurality of PUSCHs, receiving information on the number of repetitive transmissions determined based on the feedback from the base station, and repetitive transmission of second data based on the information on the number of repetitive transmissions It may include performing steps.

According to another aspect of the present invention, a method of transmitting data by a terminal in a wireless communication system includes receiving a feedback on uplink data transmitted by the terminal from a base station, and retransmitting the uplink data based on the feedback. Determining whether the uplink data is retransmitted, setting the size of the code block group of the uplink data based on the type of the uplink data, and the uplink in units of the adjusted code block group It may include retransmitting the link data.

According to one side, the uplink data includes URLLC (Ultra-Reliable and Low Latency Communication) data, and the size of the code block group is greater than the size of the code block group for retransmission of eMBB (enhanced 　 Mobile 　 Broad Band) data. Can be set small.

According to another aspect, prior to the receiving step, the size of a code block group for retransmission of the URLLC data from the base station through at least one of a radio resource control (RRC) message and downlink control information It may further include the step of receiving information.

According to another aspect, the information on the size of the code block group may be information on the maximum number of code block groups per transport block for the URLLC data.

According to another aspect, the maximum number of code block groups per transport block for the URLLC data may be set separately from the maximum number of code block groups per transport block for the eMBB data.

According to another aspect of the present invention, a method of transmitting data by a base station in a wireless communication system includes the steps of receiving a feedback on downlink data transmitted by the base station from a terminal, and whether to retransmit the downlink data based on the feedback. Determining, when retransmitting the downlink data, setting a size of a code block group of the downlink data based on a type of the downlink data, and the downlink in units of the adjusted code block group It may include retransmitting the data.

According to another aspect of the present invention, a method for transmitting data by a terminal in a wireless communication system is provided. The data transmission method includes receiving information on the number of repetitive transmissions for a physical uplink shared channel (PUSCH) from a base station, and information on frequency hopping applied to repetitive transmission of the PUSCH from the base station. Receiving, configuring repeated transmission of the PUSCH, determining a frequency resource for repeated transmission of the PUSCH based on the frequency hopping information, and performing repeated transmission of the PUSCH do.

According to another aspect of the present invention, the frequency hopping range is implemented by changing according to the size of a bandwidth part (BWP) activated for repetitive transmission of the PUSCH.

According to another aspect of the present invention, further comprising the step of receiving information on the length of a mini-slot used for repeated transmission of the PUSCH, wherein the repeated transmission of the PUSCH is performed in units of the mini-slot Is implemented.

According to another aspect of the present invention, the frequency resource is implemented as a frequency resource corresponding to both ends of the activated bandwidth portion.

According to another aspect of the present invention, the data transmission method further comprises transmitting channel quality information to the base station, and the frequency hopping information is determined based on the channel quality information. Is implemented.

According to another aspect of the present invention, the information on the frequency hopping is implemented to include information on whether to apply the frequency hopping and information on a frequency hopping pattern.

According to another aspect of the present invention, the information on the number of repetitive transmissions includes information on the number of repetitive transmissions by default, and information on a difference value between the number of repetition transmissions and the actual number of repetitions of the PUSCH. Is implemented by

According to another aspect of the present invention, the information on the number of repetitive transmissions is a Radio Resource Control (RRC) message and includes at least one of a maximum number of repetitive transmissions and a basic repetition number of transmissions, wherein the repetitive transmission of the PUSCH is the maximum repetition. It is implemented to be configured according to the number of transmissions or the number of basic repeated transmissions.

According to another aspect of the present invention, the data transmission method includes the steps of receiving information on a new number of repeated transmissions determined based on ACK or NACK for repeated transmission of the PUSCH from the base station, and the new number of repeated transmissions. Based on the information, the implementation further includes performing repetitive transmission of a new PUSCH.

According to another aspect of the present invention, the information on the new number of repeated transmissions is implemented to be changed when the number of ACKs or NACKs is greater than or equal to a reference value, or a ratio between the ACK and NACK is greater than or equal to a reference rate.

According to another aspect of the present invention, a method is provided for a base station to transmit data in a wireless communication system. The data transmission method includes transmitting information on the number of repetitive transmissions for a physical downlink shared channel (PDSCH) to a terminal, and transmitting information on frequency hopping applied to repetitive transmission of the PUSCH to the terminal. Transmitting, configuring the repetitive transmission of the PDSCH, determining a frequency resource for repetitive transmission of the PDSCH based on the information on the frequency hopping, and performing repetitive transmission of the PDSCH do.

According to another aspect of the present invention, the frequency hopping range is implemented to be changed according to the size of a bandwidth part (BWP) activated for repetitive transmission of the PDSCH.

According to another aspect of the present invention, the data transmission method further comprises transmitting information on a length of a mini-slot used for repetitive transmission of the PDSCH to the terminal, wherein the PDSCH is repeated. Transmission is implemented to be performed in the mini-slot unit.

According to another aspect of the present invention, the frequency resource is implemented as a frequency resource corresponding to both ends of the activated bandwidth portion.

According to another aspect of the present invention, the data transmission method further comprises receiving channel quality information from the terminal, and the frequency hopping information is determined based on the channel quality information. Is implemented.

According to another aspect of the present invention, the information on the frequency hopping is implemented including information on whether to apply the frequency hopping and information on a frequency hopping pattern.

According to another aspect of the present invention, the information on the number of repetitive transmissions includes information on the number of default repetitive transmissions, and information on a difference value between the number of basic repetitions and the actual number of repetitions of the PDSCH. Is implemented by

According to another aspect of the present invention, the information on the number of repetitive transmissions is a Radio Resource Control (RRC) message and includes at least one of a maximum number of repetitive transmissions and a basic repetition number of transmissions, and the repetitive transmission of the PDSCH is the maximum repetition. It is implemented to be configured according to the number of transmissions or the number of basic repeated transmissions.

According to another aspect of the present invention, the data transmission method includes transmitting information on a new number of repeated transmissions determined based on ACK or NACK for repeated transmission of the PDSCH to the terminal, and the new number of repeated transmissions. Based on the information, the implementation further includes performing repetitive transmission of the new PDSCH.

According to another aspect of the present invention, the information on the new number of repeated transmissions is implemented to be changed when the number of ACKs or NACKs is greater than or equal to a reference value, or a ratio between the ACK and NACK is greater than or equal to a reference rate.

According to the present invention, when data corresponds to ultra-reliable low latency communication (URLLC), since the transmitter can repeatedly transmit the same data more than once using frequency hopping based on a mini slot, data can be transmitted more quickly and stably. Can be transmitted.

In addition, the number of repetitive transmissions of data can be optimized, and accordingly, the overhead of HARQ feedback can be reduced.

In addition, when URLLC data is retransmitted by HARQ, time delay may be reduced, and retransmission may be performed more efficiently in terms of resource allocation and resource use required for transmission.

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 illustrating an example of a frequency allocation scheme and a BWP to which the technical features of the present invention can be applied.

6 is a diagram illustrating an example of a bandwidth adaptation scheme in which multiple BWPs and BWPs to which the technical features of the present invention can be applied are transmitted while changing.

7 to 13 are flowcharts illustrating a frequency hopping method according to an embodiment of the present invention.

14 is a flowchart showing a data transmission method according to an embodiment of the present invention.

15 is a flowchart illustrating a data transmission method according to another embodiment of the present invention.

16 is a flowchart illustrating a data transmission method according to another embodiment of the present invention.

17 is a diagram for explaining the concept of a code block group applied to the present invention.

18 shows a configuration of a PDSCH serving cell applied to an embodiment of the present invention.

19 shows a configuration of a PUSCH serving cell applied to an embodiment of the present invention.

20 is a diagram for describing a case of retransmitting eMBB data according to an embodiment.

21 is a diagram for describing a case of retransmitting URLLC data according to an embodiment.

22 is a flowchart illustrating a data transmission method according to another embodiment of the present invention.

23 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 is to 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. These 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. 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 this 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 such as those 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 of 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, the wireless communication system 100 includes 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 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, and 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 within 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), BTS (Base Transceiver Station), radio base station (radio base station), radio transceiver (radio transceiver), access point (access point), access node (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), relay node (relay node), etc. I can. Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 is a terminal, an access terminal, a mobile terminal, Station (station), subscriber station (subscriber station), mobile station (mobile station), portable subscriber station (portable subscriber station), node (node), may be referred to as a device (device).

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 a different frequency band 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 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) 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 OFDMA or SC-FDMA-based uplink (uplink) transmission can be supported. 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, 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 may 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 coordinate 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 Can be done.

In the following, 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 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 an operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, the terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

In addition, hereinafter, downlink (DL) refers to communication from a base station to a terminal, and uplink (UL) refers to 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 part of the terminal, and the receiver may be 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 a service and/or terminal sensitive to communication reliability and/or latency. It is being discussed.

Hereinafter, in the present 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.

Referring to Figure 2, NG-RAN (Next Generation-Radio Access Network) is NG-RA user plane (SDAP/PDCP/RLC/MAC/PHY) and control plane (RRC) protocol termination for UE (User Equipment). It consists of gNBs that provide. (NG-RAN may also include an eNB, which is an existing LTE base station.) Here, NG-C represents a control plane interface used for an NG2 reference point between the 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 (SCS) and cyclic prefix (CP) overhead. In this case, a 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 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 TDD (Time Division Duplexing) structure considered in the NR system is a structure that processes both uplink (UL) and downlink (DL) in one slot (or subframe). This is for minimizing 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 be composed of 14 OFDM symbols (when an extended CP is used, it is composed of 12 OFDM symbols). In FIG. 3, region 310 represents a downlink control region, and region 320 represents an uplink control region. In this case, different from that shown in FIG. 3, the number of symbols used as downlink and uplink control regions in one slot may be greater than one, respectively. Regions other than regions 310 and 320 (ie, regions without separate indication) may be used for transmission of downlink data or uplink data. That is, the uplink control information and the downlink control information may be transmitted in one slot. In addition, even in the case of data, uplink data and 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, a time required to retransmit data may be reduced. Through this, a 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 in which a base station and/or a terminal switches from a transmission mode to a reception mode or a process 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. (The transmission method based on the mini-slot is also referred to as the non-slot transmission method.) The mini-slot is the minimum scheduling unit by the base station, and can be transmitted in a unit smaller than the slot (1 to 13 symbols). For example, it may be composed of 2, 4 or 7 OFDM symbols.

The mini-slot can 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, it is necessary to transmit data stably and quickly with little errors for communication in various application fields corresponding to V2X (Vehicle to Everything) and URLLC scenarios. In particular, 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 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, and thus, 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. Accordingly, in the present invention, the same data may be repeatedly transmitted or repeatedly 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.

Hereinafter, resource allocation in the NR system will be described.

In the NR system, a specific number (for example, a maximum of 4 downlink and uplink respectively) of bandwidth parts (BWP) may be defined. The BWP (or carrier BWP) is a set of continuous PRBs, and can be expressed as a continuous subset of common RBs (CRBs). Each RB in the CRB starts with CRB0 and can be represented by CRB1, CRB2, and the like.

<Repetitive transmission method using frequency hopping and apparatus therefor>

5 is a diagram illustrating an example of a frequency allocation scheme and BWPs to which the technical features of the present invention can be applied.

Referring to FIG. 5, a number of BWPs may be defined in a CRB grid. The reference point of the CRB grid (which can be referred to as a common reference point, starting point, etc.) is called the so-called "point A" in NR. Point A is indicated by RMSI (ie, SIB1). Specifically, a frequency offset between the frequency band in which the SS/PBCH block is transmitted and the point A may be indicated through RMSI. Point A corresponds to the first subcarrier of CRB0. In addition, point A may be a point at which a variable “k” indicating the frequency band of RE in NR is set to 0. A plurality of BWPs shown in FIG. 5 are configured with one cell (eg, a PCell (primary cell)). A plurality of BWPs may be individually or commonly configured for each cell.

Referring to FIG. 5, each BWP may be defined by a size and a starting point from CRB0. For example, the first BWP, that is, BWP #0, may be defined by a starting point through an offset from CRB0, and the size of BWP#1 may be determined through the size of BWP#0. Each BWP may be defined to overlap within the entire channel bandwidth (CBW).

A specific number of BWPs (eg, a maximum of 4 in each of downlink and uplink) may be configured for the terminal. In the 3GPP Release 15 standard, even if a plurality of BWPs are configured, only a specific number (eg, 1) of BWPs can be activated per cell for a given time period. In the future, the standard may be changed so that multiple BWPs can be activated during a given time. However, when a supplementary uplink (SUL) carrier is configured in the terminal, up to four BWPs may additionally be configured on the SUL carrier, and one BWP may be activated for a given time. The number of configurable BWPs or the number of activated BWPs may be configured individually or in common for UL and DL. In addition, the neurology and/or CP for DL BWP, and the neurology and/or CP for UL BWP may be configured in the terminal through DL signaling. The UE may receive PDSCH, PDCCH, channel state information (CSI) RS and or tracking RS (TRS) only in the active DL BWP. In addition, the UE may transmit a PUSCH and/or a physical uplink control channel (PUCCH) only to the active UL BWP.

6 is a diagram illustrating an example of Bandwidth Adaptation used while temporally changing multiple BWPs to which the technical features of the present invention can be applied.

6 is an assumption that three BWPs are set. The first BWP may span a 40 MHz band, and a subcarrier spacing of 15 kHz may be applied. The second BWP may span a 10 MHz band, and a subcarrier spacing of 15 kHz may be applied. The third BWP may span a 20 MHz band, and a subcarrier spacing of 60 kHz may be applied. The terminal may configure at least one BWP of the three BWPs as an active BWP, and may perform UL and/or DL data communication through the active BWP.

The time resource may be indicated in a manner indicating a time difference/offset based on a transmission time of a PDCCH allocating a DL or UL resource. For example, the starting point of the PDSCH/PUSCH corresponding to the PDCCH and the number of symbols occupied by the PDSCH/PUSCH may be indicated.

In the NR system, like LTE/LTE-A, carrier aggregation (CA) may be supported. That is, it is possible to increase a bandwidth by aggregating a continuous or discontinuous component carrier (CC), and consequently, an increase in a bit rate. Each CC may correspond to a (serving) cell, and each CC/cell may be divided into a primary serving cell (PSC)/primary CC (PCC) or a secondary serving cell (SSC)/secondary CC (SCC).

In addition, single beam and multiple beam formation may be supported in the NR system.

The network can deploy a single beam or multiple beams. Different single beams can be used at different times. Regardless of whether a single beam or multiple beams are deployed, from the perspective of the UE, it may be necessary to indicate the resources to be monitored for control channel monitoring. In particular, when multiple beams are used or repetition is used, the same control channel may be transmitted multiple times from the UE point of view.

In the NR system, for communication in various application fields corresponding to V2X (Vehicle to Everything) and URLLC scenarios, it is necessary that the transmitted data be transmitted stably and quickly with little errors. In particular, 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 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, and thus, 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. Accordingly, in the present invention, the same data may be repeatedly transmitted or repeatedly 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.

7 to 13 are flowcharts illustrating a frequency hopping method according to an embodiment of the present invention.

According to the present embodiment, when a transmitter repeatedly or repeatedly transmits the same information (same data) to a receiver, frequency hopping (FH) may be performed in the frequency domain. Here, when the transmitter is a terminal, the receiver may be a base station or another terminal. When the transmitter is a base station, the receiver may be a terminal.

As an example, the terminal may perform frequency hopping in the frequency domain in units of mini-slots when repeatedly or redundantly transmitting the same data to the base station. For example, after the terminal configures a plurality of PUSCHs corresponding to the number of repetition transmissions, the first PUSCH is transmitted to the base station using a first frequency in the first minislot, and the second PUSCH is temporally with the first minislot. It is possible to transmit to the base station using a second frequency according to frequency hopping in the adjacent second mini-slot. Here, the same uplink data may be identically mapped to each PUSCH.

As another example, when transmitting the same data repeatedly or redundantly to the terminal, the base station may perform frequency hopping in the frequency domain in units of mini-slots. For example, after the base station configures a plurality of PDSCHs corresponding to the number of repetitive transmissions, the first PDSCH is transmitted to the terminal using a first frequency in the first minislot, and the second PUSCH is temporally associated with the first minislot. It can be transmitted to the terminal using the second frequency in the adjacent second mini-slot. Here, the same downlink data may be identically mapped to each PDSCH.

This embodiment can be applied equally to a sidelink transmission environment.

In this case, the transmitter may be a transmitting terminal and the receiver may be a receiving terminal. Data transmitted through the sidelink may be referred to as PSSCH or PSSCH data, or may be referred to as URLLC data.

In addition, the range of frequencies used for frequency hopping in this embodiment may vary according to the size of the bandwidth part (BWP). For example, the transmitter may use frequency resources corresponding to both ends of the BWP in the FH in order to maximize the frequency diversity effect. For example, as shown in FIG. 7, when the BWP is composed of 10 PRBs (PRB #0 to PRB #9) and 4 repetitive transmissions are set, the transmitter is within the BWP in the first minislot and the third minislot. The same data may be transmitted using PRB #0, which is the lowest frequency resource, and the same data may be transmitted using PRB #9, which is the highest frequency resource in the BWP, in the second minislot and the fourth minislot.

Alternatively, unlike FIG. 7, the transmitter transmits the same data using PRB #9 in the first minislot and the third minislot, and the same data using PRB #0 in the second and fourth minislots. Can also be transmitted.

On the other hand, when more frequency resources (Resource Block: RB) are required for data transmission, the transmitter can use several frequency resources while increasing the number of RBs from the end of the BWP. For example, as shown in FIG. 8, in a situation in which the BWP consists of 10 PRBs (PRB#0 to PRB#9) and 4 repetitive transmissions are set, the transmitter PRBs in the first minislot and the third minislot. The same data may be transmitted using #0 and PRB #1, and the same data may be transmitted using PRB #8 and PRB #9 in the second minislot and the fourth minislot. Alternatively, unlike FIG. 8, the transmitter transmits the same data using PRB #8 and PRB #9 in the first minislot and the third minislot, and PRB #0 and the fourth minislot in the second minislot and the fourth minislot. The same data can also be transmitted using PRB #1.

In addition, when there is a large amount of URLLC traffic to which frequency hopping is applied, collision of frequency resources should not occur. In particular, when resources to be used for frequency hopping are overlapped between several terminals, it is necessary to adjust the range of frequency hopping so that frequency resources do not collide. To this end, when frequency hopping is applied, the frequency resource at the end of the BWP may be basically used, but may be changed if necessary. For example, if four repetitive transmissions are set for the first terminal and the second terminal, and the frequency hopping resource of the first terminal and the frequency hopping resource of the second terminal overlap, the first terminal is Based on the frequency resources PRB #0 and PRB #9, which are basically set for hopping, the same data is repeatedly transmitted using frequency hopping in mini-slot units, and the second terminal basically adjusts the frequency hopping range within the BWP. The same data can be repeatedly transmitted using frequency hopping in units of mini-slots based on PRB #1 and PRB #8, which are inner frequency resources of the set frequency resource. Alternatively, as shown in FIG. 10, by adjusting the frequency hopping range for both the first terminal and the second terminal, the first terminal repeatedly transmits data using PRB #0 and PRB #8, and the second terminal repeatedly transmits data to PRB #1. And PRB #9 can be used to repeatedly transmit data. Alternatively, as shown in FIG. 11, the first terminal and the second terminal may use the same frequency resource, but may repeatedly transmit the same data using different frequency hopping patterns.

Meanwhile, when the same data is repeatedly transmitted, frequency hopping may not be performed within one mini-slot in order to reduce complexity. When multiple mini-slots are used to repeatedly transmit the same data, frequency hopping may be applied. When redundant or repetitive transmission occurs over multiple slots, a frequency different from the frequency used in the previous slot may be used in the next slot. That is, the FH between slots may be applied. In this case, for example, when the base station or the transmitting terminal can trust channel information (channel gain for each frequency, etc.), frequency hopping is not applied, and data is repeatedly transmitted by allocating a frequency resource having a good channel state. I can.

Such frequency hopping-related information, for example, FH-related configuration information, may be set by the base station to be semi-static by using higher layer Radio Resource Control (RRC) signaling, etc., and may inform the terminal thereof. In addition, control information related to the FH may be included in the DCI and transmitted through the PDCCH. In the case of a sidelink transmission environment, the FH-related information may be transmitted by the base station to the terminal through higher layer signaling such as RRC or the transmitting terminal to the receiving terminal. For example, the base station may inform the terminal of information on whether or not FH is applied, information on the FH pattern, and the like through DCI. That is, the base station may inform the terminal by including control information for transmitting and receiving data in such a transmission method in the DCI. In this case, a new field may be added to the DCI. When the transmitting terminal repeatedly or redundantly transmits data to the receiving terminal, the transmitting terminal may inform the receiving terminal of information on whether FH is applied, information on the FH pattern, etc. through Sidelink Control Information (SCI).

In uplink transmission or downlink transmission, the length of the mini-slot and the number of repetitive transmissions may be informed by the base station to the terminal through DCI. However, the number of repetitive transmissions may be set by notifying the RRC in advance. For example, the base station may inform the default number of repetitive transmissions by RRC, and when the basic repetition number of transmissions needs to be changed, the base station may inform the terminal of the actual number of repetitive transmissions through DCI. In this case, information on a difference value between the basic number of repetitive transmissions and the actual number of repetitive transmissions may be included in the DCI.

In side link transmission, the length of the mini-slot and the number of repetitive transmissions may be informed by the transmitting terminal or the base station to the receiving terminal through SCI or DCI.

Meanwhile, when frequency hopping is used, a separate demodulation reference signal (DMRS) may be applied for each repetitive transmission. However, when the transmitter repeatedly transmits the same data to the receiver using the same frequency resource, the DMRS may not be used separately. That is, repeated transmission may be performed several times with one DM-RS. However, if the channel is changed quickly, the DM-RS may be used separately even if the same frequency resource is used. That is, a separate DM-RS may be applied to each repetitive transmission.

In addition, the number of DM-RSs used during repeated transmission may be applied differently according to the service or QoS of the service. For example, when moving at a high speed, a DM-RS may be separately applied for each repetitive transmission, and when moving slowly, a single DM-RS may be repeatedly transmitted several times.

Meanwhile, in the case of very important information, the same information may be transmitted repeatedly in the frequency domain and the time domain. As an example, the transmitter may allocate multiple frequency resources and transmit the same information multiple times to each frequency resource. For example, as shown in FIG. 12, the transmitter may map the same data to PRB#0 and PRB#9, respectively, and transmit the same data to the first minislot to the fourth minislot. This method may be more suitable in a mm-Wave environment where there are many frequency resources and short time resources.

As another example, the transmitter may transmit the same information multiple times using all of different frequency and time resources. For example, as shown in FIG. 13, the transmitter performs frequency hopping using PRB#0 and PRB#9 when repeating the first data transmission, and the optimal frequency resource based on CQI for the second data identical to the first data. (In FIG. 13, RPB #5) may be used to perform repeated transmission.

In the above-described embodiment, frequency hopping resources may be derived based on Table 1 below.

Referring to Table 1, a frequency hopping offset during repeated transmission may be determined based on the number of RPBs in the active uplink BWP. In addition, the frequency hopping pattern may be determined according to the value of the hopping bit. This frequency hopping resource determination method can be applied equally to downlink.

14 is a flowchart showing a data transmission method according to an embodiment of the present invention.

According to the present embodiment, the transmitter may repeatedly transmit the same data to the receiver in various ways according to the channel state. Here, the transmitter may be a base station or a transmitting terminal, and the receiver may be a base station or a receiving terminal.

As an example, a case in which the UE repeatedly transmits uplink data to the base station will be described with reference to FIG. 14.

The base station may determine whether to apply frequency hopping to uplink data intended to be transmitted by the corresponding terminal based on the CQI report received from the terminal. To this end, the terminal may check the channel state and transmit a CQI report to the base station (S1410). The base station checks the channel status based on the CQI value included in the CQI report received from the terminal, and if the channel status is good, determines that the corresponding data is repeatedly transmitted without applying frequency hopping, and the channel status is not good , When channel information is unknown or unreliable, it may be determined to apply frequency hopping during repeated transmission. In addition, the base station may transmit a DCI including information on the number of repetitive transmissions for uplink data and information on frequency hopping to the corresponding terminal. Here, the DCI may further include information on the length of a mini-slot used for repeated transmission in addition to information on the number of repetitive transmissions and information on frequency hopping. In addition, the information on frequency hopping may include information on whether frequency hopping is applied and/or information on a frequency hopping pattern.

When the terminal receives the DCI from the base station, it may determine whether to perform frequency hopping based on this (S1420). If it is determined to perform repetitive transmission without applying frequency hopping, the terminal may repeatedly transmit the same data using an optimal frequency resource (S1430). In this case, the terminal may repeatedly transmit the same data using a plurality of frequency and/or time resources according to the importance of the data.

However, when it is determined to apply frequency hopping during repetitive transmission, the terminal transmits the first data using the first frequency in the first mini-slot (S1440), and in a second mini-slot temporally adjacent to the first mini-slot. The same data as the first data may be repeatedly transmitted to the receiver by using the second frequency according to frequency hopping (S1450). In this case, the terminal may repeatedly transmit the same data by using at least one of the frequency hopping methods of FIGS. 7 to 13.

As an example, when DCI is received from the base station, the terminal configures a plurality of PUSCHs corresponding to the number of repeated transmissions based on information on the number of repeated transmissions included in the DCI, and information about frequency hopping included in the DCI Frequency resources for transmission of a plurality of PUSCHs may be determined based on. In this case, the uplink data may be identically mapped to the plurality of PUSCHs. In addition, the range of frequency hopping during repeated transmission may be changed according to the size of the BWP activated for transmission of the corresponding uplink data.

<Communication method based on the number of adaptively controlled repetitive transmissions>

15 is a flowchart showing a data transmission method according to an embodiment of the present invention.

In this embodiment, the transmitter may transmit the same information (same data) to the receiver repeatedly or repeatedly. When the UE repeatedly or duplicates the same data and transmits the same data to the base station, the data may be referred to as PUSCH or PUSCH data. Alternatively, the data may be referred to as data related to URLLC. When the base station repeatedly or duplicates the same data and transmits the same data to the terminal, the data may be referred to as PDSCH or PDSCH data. Alternatively, the data may be referred to as data related to URLLC. When the transmitting terminal transmits the same data repeatedly or redundantly to the receiving terminal, the data may be referred to as PSSCH or PSSCH data or data related to URLLC.

As an example, FIG. 15 illustrates a case where a transmitter is a base station and a receiver is a terminal.

Referring to FIG. 15, basically, the number of repetitive transmissions and the maximum number of repetition transmissions may be set by a base station to be semi-static or static in Radio Resource Control (RRC). For example, the base station may inform the terminal of information on the default number of repetitive transmissions and/or the maximum number of repetitive transmissions through higher layer signaling such as an RRC message (S1510). That is, the value set in the RRC is the maximum number of repeated transmissions or the basic number of repeated transmissions, or both can be set if necessary.

For example, the base station may configure a plurality of PDSCHs for the first data based on information on the basic number of repetitive transmissions or the maximum number of repetitive transmissions. That is, the first data may be identically mapped to the plurality of PDSCHs. The base station may repeatedly transmit the first data by transmitting a plurality of PDSCHs to which the first data is identically mapped to the terminal using different time and/or frequency resources (S1520). Here, the maximum number of repeated transmissions may be set as the basic number of repeated transmissions. In this case, the base station can transmit only information on the maximum number of repetitive transmissions in an RRC message, and the terminal can recognize that the maximum number of repetitive transmissions is used as the basic repetition number of transmissions.

The receiver transmits ACK/NACK for each case of repeated transmission, and the transmitter may determine the optimal number of repeated transmissions in consideration of this. Referring to FIG. 5 as an example, when a plurality of PDSCHs are received from a base station, the UE decodes them (S1530), transmits a HARQ ACK for a successfully received PDSCH, and transmits a HARQ NACK for a PDSCH in which an error occurs. Can be (S1540). The base station may determine the number of repetitive transmissions for the second data (data repeatedly transmitted after the first data) based on the number of HARQ ACKs received from the terminal and/or the number of HARQ NACKs received (S1550). In this case, the UE may use a Chase Combining (CC) method and/or an Incremental Redundancy (IR) method in determining the need for retransmission of the corresponding data. The CC scheme may be used when the same redundancy version is applied to all of the plurality of PDSCHs, and the IR scheme may be used when different redundancy versions are applied to each of the plurality of PDSCHs. For example, when an error occurs in the first PDSCH when decoding a plurality of PDSCHs, the UE may correct an error occurring in the first PDSCH and/or the second PDSCH by combining the first PDSCH with the second PDSCH. have. If an error occurs in all of the plurality of PDSCHs, but the data is successfully decoded as a result of combining them, the UE may transmit a HARQ ACK instead of HARQ NACK for the last received PDSCH. In this case, although the base station can recognize that the channel condition is not good through HARQ feedback, the base station can prevent the case where the base station unnecessarily retransmits the corresponding data because the terminal has successfully received the corresponding data.

After performing repetitive transmission, the transmitter determines that the channel state is in a very good state if the number of ACKs for the repetitive transmission is greater than or equal to the reference value ( When transmitting the next data in a similar channel environment, it is possible to perform repetitive transmission by reducing the number of repetitions, but if the number of ACKs is less than the reference value or the reference ratio after performing repetitive transmission, the transmitter determines that the channel is in a poor state. When transmitting the next data (second data) in a similar channel environment (an environment corresponding to the channel environment at the time of transmitting the first data), it is possible to perform repetitive transmission by increasing the number of repetitions. The number of times of transmission may be changed when the channel environment when transmitting the second data corresponds to the channel environment when transmitting the first data.

For example, when the base station receives HARQ ACKs greater than or equal to the reference value for a plurality of PDSCHs from the terminal, if the second data is to be repeatedly transmitted in a channel environment similar to when the first data is repeatedly transmitted, the second data is The number of repetitive transmissions of the first data may be reduced than the number of repetitive transmissions of the first data. As another example, when the base station receives HARQ ACKs less than the reference value for a plurality of PDSCHs from the terminal, if the second data is to be repeatedly transmitted in a channel environment similar to when the first data is repeatedly transmitted, the second data is The number of repetitive transmissions of the first data may be increased than the number of repetitive transmissions of the first data. Thereafter, the base station informs the terminal of information on the number of repetitive transmissions for the second data through DCI, and configures the number of PDSCHs corresponding to the number of repetition transmissions using the second data and transmits it to the terminal (S560). .

In this case, the base station may change the number of repeated transmissions after performing the repeated transmission a predetermined number of times as the basic number of repeated transmissions. How many initial transmissions are performed and then the number of repeated transmissions to be updated again may be set with another parameter. (Example: 1, 2, 4, 6,... etc.)

For example, if the parameter for the update of the number of repetitive transmissions is set to '2', the base station repeatedly transmits the first data and the second data at the basic repetition number of times, and then the number of repetitions for the third data is zero. It may be determined based on the number of HARQ ACKs and/or NACKs for 1 data and/or second data.

For repeated transmission after that, the base station may change in real time within the range set in the RRC, and the corresponding information may be included in the DCI to inform the terminal. For example, the base station may initially set a number of repetitive transmission times with RRC, and then inform only a difference value between the current repetition transmission count and the previous repetition transmission count with DCI. Alternatively, it may inform only the up or down of the number of repetitive transmissions. For example, the base station may set the number of repetitive transmissions to (2, 4, 6, 8) by RRC and set the number of basic repetitive transmissions to '2'. In this case, when the base station instructs the number of repetitive transmissions up to the DCI, the terminal may change the basic repetition number of transmissions from '2' to '4'.

In addition, the base station may inform whether to enable/disable repetitive transmission through DCI. Therefore, according to this embodiment, the number of repetitive transmissions can be optimized, and accordingly, the number of ACK/NACKs can be reduced.

Meanwhile, in the present embodiment, repetitive transmission is applicable to both the time axis and the frequency axis. That is, the transmitter can dynamically set how many times the same information is repeatedly transmitted using different time and/or frequency resources.

In repetitive transmission, the more high-frequency bands are used, the more repetitive situations can occur in the frequency axis. To achieve ultra-low latency, it may be advantageous to transmit repeatedly in the frequency axis. However, in some cases, time resources may be used repeatedly. For example, the transmitter may transmit first data using a first frequency source on a first slot or a first mini-slot, and transmit the same data as the first data using a second frequency resource. As another example, the transmitter transmits first data using a first frequency resource on a first slot or a first mini-slot, and on a second slot or a second mini-slot that is temporally adjacent to the first slot or the first mini-slot. The same data as the first data may be transmitted using the first frequency resource or the second frequency resource.

Meanwhile, as another embodiment, the number of repetitive transmissions may be changed according to channel conditions such as CQI. For example, the transmitter may reduce the number of repetitive transmissions when the channel condition is good, and increase the number of repetitive transmissions when the channel condition is bad. Information on the increase and/or decrease of the number of repetitive transmissions may be transmitted to the receiver through DCI, SCI, UCI, or the like. In this case, it may be more appropriate to set the number of repetitions to be semi-static than to set to dynamic.

16 is a flowchart illustrating a data transmission method according to another embodiment of the present invention.

In FIG. 16, a case where a transmitter is a terminal and a receiver is a base station is shown. However, even if both the transmitter and the receiver are terminals, repetitive transmission may be similarly performed.

Referring to FIG. 16, basically, the number of repetitive transmissions and the maximum number of repetition transmissions may be semi-statically or statically set as RRC by the base station. For example, the base station may inform the terminal of the basic number of repetitive transmissions and/or the maximum number of repetitive transmissions through higher layer signaling such as RRC (S1610). That is, the value set in RRC may be the maximum number of repetitive transmissions and/or the number of basic repetition transmissions.

The UE may configure a plurality of PUSCHs for the first data based on the information on the maximum number of repetitive transmissions or the number of basic repetitions (S1620). Here, the first data may be identically mapped to the plurality of PUSCHs. The terminal may repeatedly transmit the plurality of PUSCHs to the base station using different time and/or frequency resources (S1630).

When the base station receives a plurality of PUSCHs from the terminal, the base station performs decoding on them (S1640), and may transmit feedback (multiple ACK/NACK) for each repetitive transmission (multiple PUSCH) to the terminal (S1650). In this case, the base station may determine the optimal number of repetitive transmissions based on the number of ACKs and/or the number of NACKs included in the feedback (S1660).

For example, when a plurality of PUSCHs are received from the terminal, the base station decodes them, and then transmits HARQ ACK for successfully received PUSCHs and HARQ NACK for PUSCHs in which errors occur. The base station may determine the number of repetitive transmissions of the second data based on the channel state determined based on the PUSCH received from the terminal, the number of transmitting HARQ ACKs and/or the number of transmitting HARQ NACKs.

In addition, the base station may use the CC method and/or the IR method to determine the need for retransmission of the corresponding data. For example, when an error occurs in the first PUSCH when decoding a plurality of PUSCHs, the base station may combine the first PUSCH with the second PUSCH to correct the error occurring in the first PUSCH and/or the second PUSCH. If an error occurs in all of the plurality of PUSCHs, but the data is successfully decoded as a result of combining them, the base station transmits HARQ ACK rather than HARQ NACK for the last received PUSCH, so that the terminal does not unnecessarily retransmit the corresponding data. Can be avoided.

The transmitter may inform the receiver of information on the number of repetitive transmissions of the second data through control information such as DCI.

As an example in FIG. 16, although it is shown that the number of repetitive transmissions is determined by the base station, when the transmitter is the transmitting terminal and the receiver is the receiving terminal, the number of repetitive transmissions may be determined by the transmitting terminal or the receiving terminal. .

<CBG-based transmission method and device therefor>

17 is a diagram for explaining the concept of a code block group applied to the present invention.

In the NR system, retransmission due to HARQ is performed in units of a code block group (CBG), which is a unit smaller than a unit of a transport block (TB). As an example, referring to FIG. 17, one TB may be segmented into eight code blocks (CBs), and three code blocks may be grouped into one CBG. However, this is only an example, and one CBG may be configured with one code block, and one TBG may be configured with one CBG.

18 is a diagram showing a configuration of a PDSCH serving cell applied to an embodiment of the present invention, and FIG. 19 is a diagram showing a configuration of a PUSCH serving cell applied to an embodiment of the present invention.

18 and 19, a maximum of 2, 4, 6, or 8 CBGs per TB may be configured by higher layer signaling in both uplink transmission and downlink transmission. CBG is a group of code blocks such as 2, 4, 6, 8, etc., and is used as a unit of HARQ retransmission, and is reflected in DCI.

DCI format 0_1 used for PUSCH scheduling is shown in Table 2 below, and DCI format 1_1 used for PDSCH scheduling is shown in Table 3 below.

However, in general, since URLLC data has a smaller data size than eMBB data and requires low latency, a unit (or size) of CBG needs to be set to a unit smaller than eMBB. Therefore, according to this embodiment, differently from the CBG for eMBB, the CBG for URLLC may be separately set. As an example, the CBG for URLLC may be composed of 1, 2, 3 or 4 code blocks. Alternatively, in the case of URLLC, the maximum number of CBGs included in one TB may be set to 4, 8, 12 or 16. That is, when URLLC data is retransmitted, the maximum number of CBGs included in the TB is determined according to the TB size, and as a result, the size unit of the retransmitted data may be set smaller than that of the eMBB.

For example, in the case of URLLC, if the TB size is the same as eMBB, the maximum number of CBGs per TB for URLLC may be set larger than eMBB. If the TB size is smaller than that of eMBB, the maximum number of CBGs per TB for URLLC may be set similarly to eMBB. That is, according to an embodiment, the maximum number of CBGs per TB for URLLC may be set by RRC, apart from the maximum number of CBGs per TB for eMBB.

Information on CBG for URLLC may be indicated by RRC, and if necessary, DCI setting may be changed or added to reflect this. As an example, a field for CBG transmission information for URLLC may be added to DCI format 0_1 of Table 1 and/or DCI format 1_1 of Table 2. As an example, the CBG transmission information for the URLLC is set to any one of 0, 2, 4, 6, 8, 10, 12, 14, or 16 bits, so that when the URLLC data is retransmitted, the corresponding CBG is retransmitted in the form of a bitmap. Can be indicated by

Meanwhile, as RRC, a maximum number of CBGs per TB for URLLC may be set separately from the maximum number of CBGs per TB (2, 4, 6, 8) currently set for eMBB. For example, a maximum number of CBGs per TB for URRLC may be set in the RRC message of FIG. 6 and/or 7.

In addition, {n1, n2, n4, n8} may be added as information on the number of CBs (CodeBlocksPerCodeBlockGroup for URLLC) per CBG. As another example, {n4, n8, n12, n16} may be added to the RRC message of FIG. 6 and/or 7 as information on the number of maximum CBGs (maxCodeBlockGroupsPerTransportBlock for URLLC) per TB for URRLC.

As another example, if RRC is not separately set for the CBG for URLLC, if the data corresponds to URLLC, the maximum number of CBGs per TB (2, 4, 6, 8) is separately recognized as (4, 8, 12, 16). It can be mapped to a table for URLLC of. For example, if the number of CBGs per TB for eMBB data is set to '2' by the base station, the terminal sets the number of CBGs per TB to '4' for URLLC data based on information set in the ULLC table, and 4 Among the CBGs, only CBGs including data in which an error has occurred may be retransmitted.

When this scheme is applied, the retransmission time of URLLC data by HARQ can be reduced, and retransmission of URLLC data having a relatively small data size can be more efficiently performed.

FIG. 20 is a diagram for describing a case of retransmitting eMBB data according to an embodiment, and FIG. 21 is a diagram for describing a case of retransmitting URLLC data according to an embodiment.

First, referring to FIG. 20, a case in which one TB is set to two CBGs and one CBG is composed of four CBs is illustrated. When eMBB data is initially transmitted, since the transmitter performs transmission in TB units, CB #0 to CB #7 are transmitted to the receiver.

In this case, when an error occurs in at least one of CB #0 to CB #3, that is, when the transmitter receives HARQ NACK for at least one of CB #0 to CB #3 from the receiver, the transmitter includes the corresponding CB Retransmits only the CGB#1 that is used. On the other hand, as shown in FIG. 21, in the case where the CB (CB#1) in which an error occurs corresponds to URLLC data in the same situation as in FIG. 20, the transmitter configures the CGB with a size smaller than the size of CBG for eMBB data, Data can be retransmitted. To this end, the transmitter may increase the number of CBGs of initially transmitted TBs by increasing the number of maximum CGBs per TB when retransmitting URLLC data, or may decrease the number of CBs per CGB. Therefore, according to the present embodiment, since URLLC data can be retransmitted in smaller units than when eMBB data is retransmitted, retransmission with lower latency and higher efficiency is possible.

22 is a flowchart showing a data transmission method according to an embodiment of the present invention.

Hereinafter, a method of transmitting data from a transmitter to a receiver according to the present embodiment will be described with reference to FIG. 22. In this embodiment, when the transmitter is a base station, the receiver may be a terminal, and when the transmitter is a terminal, the receiver may be a base station or another terminal. When the receiver is a base station, the data may be referred to as URLLC data, uplink data, PUSCH or PUSCH data. When the receiver is a different terminal, the data may be referred to as URLLC data, sidelink data, PSSCH or PSSCH data. When the transmitter is a base station, the data may be referred to as URLLC data, downlink data, PDSCH or PDSCH data.

For example, when the transmitter is the terminal and the receiver is the base station, the terminal transmits uplink data to the base station (S2210), and receives feedback on the uplink data from the base station (S2220). Here, the feedback may be HARQ ACK or HARQ NACK for the uplink data.

The terminal may determine whether to retransmit the uplink data based on the feedback (S2230). If the feedback for the uplink data transmitted to the base station is ACK, the terminal determines that the data has been successfully transmitted and skips retransmission of the data. That is, the data is not retransmitted. However, if NACK is included in the feedback, the UE may retransmit the corresponding data. In this case, the terminal may adjust the size of the CBG of the uplink data based on the type of uplink data requiring retransmission, and perform retransmission in the adjusted CBG unit. For example, when the data corresponding to NACK is eMBB data, the UE may retransmit the CGB including the code block in which the error has occurred to the base station as shown in FIG. 20. However, when the data corresponding to the NACK is URLLC data, the UE may adjust the size of the CBG as shown in FIG. 21 (S2240) and perform retransmission based on the adjusted CGB (S2250). In this case, the size of the CBG for retransmission of URLLC data may be set to be smaller than the size of the CBG for retransmission of eMBB data so that URLLC data can be transmitted faster with less resources. Information about this (information on the size of the CBG for retransmission of URLLC data) may be received from the base station through at least one of an RRC message and/or DCI. In this case, the code block group for retransmission of eMBB data includes 2, 4, 6 or 8 code blocks, and the code block for retransmission of URLLC data is 1, 2, 3 or 4 It can contain three code blocks.

As another example, when the transmitter is the base station and the receiver is the terminal, the base station determines whether to retransmit the corresponding data based on the feedback on the downlink data transmitted to the terminal from the terminal. If the feedback is ACK, the base station determines that the data has been successfully transmitted and transmits the next data. However, if NACK is included in the feedback, the base station may adjust the size of the CBG based on the type of the corresponding data and perform retransmission in the adjusted CBG unit. For example, when the data corresponding to the NACK is eMBB data, the base station may retransmit the CGB including the code block in which the error has occurred to the terminal as illustrated in FIG. 20. However, when the data corresponding to the NACK is URLLC data, the base station may adjust the size of the CBG as shown in FIG. 21 (S2240) and perform retransmission based on the adjusted CGB (S2250). In this case, the base station may transmit information on the size of the CBG for retransmission of URLLC data to the terminal through DCI. Alternatively, information on the size of the CBG for retransmission of the URLLC data may be transmitted to the terminal in advance through an RRC message. Here, the information on the size of the CBG for retransmission of the URLLC data may be information on the maximum number of code block groups per TB for URLLC data, and is different from the information on the maximum number of code block groups per TB for eMBB data. Can be set separately.

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

Referring to FIG. 23, a terminal 2300 includes a memory 2305, a processor 2310, and a radio frequency (RF) unit 2315. The memory 2305 is connected to the processor 2310 and stores various information for driving the processor 2310. The RF unit 2315 is connected to the processor 2310 and transmits and/or receives a radio signal. For example, the RF unit 2315 may receive an RRC message posted in this specification, configuration and/or control information such as DCI, and a downlink signal such as PDSCH from the base station 2350.

In addition, the RF unit 2315 may transmit a CQI report and an uplink signal such as a PUSCH posted in the present specification to the base station 2350, or may transmit and receive a PSSCH with another terminal (not shown).

The processor 2310 implements the functions, processes, and/or methods of the terminal proposed in this specification. Specifically, the processor 2310 performs the operation of the terminal according to FIGS. 7 to 22. For example, the processor 2310 may configure a plurality of PUSCHs or a plurality of PSSCHs according to an embodiment of the present invention and transmit them using a data transmission method according to any one of FIGS. 7 to 23. In all embodiments of the present specification, the operation of the terminal 2300 may be implemented by the processor 2310.

The memory 2305 may store control information, setting information, and the like according to the present specification, and provide the control information, setting information, and the like to the processor 2310 according to a request of the processor 2310.

The base station 2350 includes a processor 2355, a memory 2360, and a radio frequency (RF) unit 2365. The memory 2360 is connected to the processor 2355 and stores various pieces of information for driving the processor 2355. The RF unit 2365 is connected to the processor 2355 and transmits and/or receives a radio signal. The processor 2355 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 2355. The processor 2355 may generate an RRC message, downlink control information, etc. posted in this specification, or may configure a plurality of PDSCHs.

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.) performing the above-described function. 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 by 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 the 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 (20)

1. In a method for transmitting data by a terminal in a wireless communication system,

   Receiving information on the number of repetitive transmissions for a physical uplink shared channel (PUSCH) from a base station;

   Receiving information on frequency hopping applied to repeated transmission of the PUSCH from the base station;

   Configuring repeated transmission of the PUSCH;

   Determining a frequency resource for repeated transmission of the PUSCH based on the frequency hopping information; And

   And performing repetitive transmission of the PUSCH.
2. The method of claim 1,

   The frequency hopping range is changed according to a size of a bandwidth part (BWP) activated for repetitive transmission of the PUSCH.
3. The method of claim 1,

   Further comprising the step of receiving information on the length of the mini-slot (mini-slot) used for repeated transmission of the PUSCH,

   Repetitive transmission of the PUSCH is performed in units of the mini-slot.
4. The method of claim 2,

   The frequency resource is characterized in that the frequency resource corresponding to both ends of the activated bandwidth portion, data transmission method.
5. The method of claim 1,

   Further comprising transmitting channel quality information to the base station,

   The information on the frequency hopping is characterized in that it is determined based on the channel quality information.
6. The method of claim 1,

   The information on the frequency hopping comprises information on whether to apply the frequency hopping and information on a frequency hopping pattern.
7. The method of claim 1,

   The information on the number of repetitive transmissions includes information on the number of repetitive transmissions by default, and information on a difference value between the number of repetitive transmissions and the actual number of repetitive transmissions of the PUSCH. .
8. The method of claim 1,

   The information on the number of repeated transmissions is a Radio Resource Control (RRC) message and includes at least one of a maximum number of repeated transmissions and a basic number of repeated transmissions,

   The repeated transmission of the PUSCH is configured according to the maximum number of repeated transmissions or the basic number of repeated transmissions.
9. The method of claim 1,

   Receiving, from the base station, information on a new number of repeated transmissions determined based on ACK or NACK for repeated transmission of the PUSCH; And

   And performing repetitive transmission of a new PUSCH based on the information on the new repetition number of transmissions.
10. The method of claim 9, wherein the information on the new number of repeated transmissions,

    When the number of ACK or NACK is greater than or equal to a reference value, or a ratio between the ACK and NACK is greater than or equal to a reference rate, the data transmission method is characterized in that it is changed.
11. In a method for transmitting data by a base station in a wireless communication system,

    Transmitting information on the number of repetitive transmissions for a physical downlink shared channel (PDSCH) to a terminal;

    Transmitting information on frequency hopping applied to repeated transmission of the PUSCH to the terminal;

    Configuring repetitive transmission of the PDSCH;

    Determining a frequency resource for repetitive transmission of the PDSCH based on the frequency hopping information; And

    And performing repeated transmission of the PDSCH.
12. The method of claim 11,

    The frequency hopping range is changed according to a size of a bandwidth part (BWP) activated for repeated transmission of the PDSCH.
13. The method of claim 11,

    Further comprising transmitting information on the length of a mini-slot used for repetitive transmission of the PDSCH to the terminal,

    Repetitive transmission of the PDSCH is performed in units of the mini-slot.
14. The method of claim 12,

    The frequency resource is characterized in that the frequency resource corresponding to both ends of the activated bandwidth portion, data transmission method.
15. The method of claim 11,

    Further comprising the step of receiving channel quality information (channel quality information) from the terminal,

    The information on the frequency hopping is characterized in that it is determined based on the channel quality information.
16. The method of claim 11,

    The information on the frequency hopping comprises information on whether to apply the frequency hopping and information on a frequency hopping pattern.
17. The method of claim 11,

    The information on the number of repetitive transmissions comprises information on the number of repetitive transmissions by default, and information on a difference value between the number of repetitive transmissions and the actual number of repetitions of the PDSCH. .
18. The method of claim 11,

    The information on the number of repeated transmissions is a Radio Resource Control (RRC) message and includes at least one of a maximum number of repeated transmissions and a basic number of repeated transmissions,

    The repetitive transmission of the PDSCH is configured according to the maximum repetitive transmission number or the basic repetition transmission number.
19. The method of claim 11,

    Transmitting information on a new number of repeated transmissions determined based on ACK or NACK for repeated transmission of the PDSCH to the terminal; And

    And performing repetitive transmission of a new PDSCH based on the information on the new repetitive transmission number.
20. The method of claim 19, wherein the information on the new number of repeated transmissions,

    When the number of ACK or NACK is greater than or equal to a reference value, or a ratio between the ACK and NACK is greater than or equal to a reference rate, the data transmission method is characterized in that it is changed.

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