User device and the methods implemented by the user device, base station and the methods implemented by the base station.

Abstract

The invention relates to a method, which is performed by a terminal device, to receive a Physical Downlink Control Channel (PDCCH) in a wireless communication system, which includes the following steps: receiving, from the base station, configuration information on the first control resource set (CORESET); receiving, from the base station, configuration information on the second CORESET; receiving, from the base station, the first PDCCH transmitted on the first CORESET; and receiving, from the base station, the second PDCCH transmitted on the second CORESET.

Description

Method for transmitting a physical downlink control channel in a wireless communication system and device therefor

[0001] This specification relates to a wireless communication system, and to a method for transmitting a physical downlink control channel and a device therefor.

[0002] Since the commercialization of 4G (4th generation) communication systems, efforts are being made to develop new 5G (5th generation) communication systems to meet the growing demand for wireless data traffic. 5G communication systems are also referred to as "beyond 4G network" communication systems, "post-LTE" systems, or "new radio" (NR) systems. To achieve high data rates, 5G communication systems include systems operating in the ultra-high frequency (mmWave) band above 6 GHz. Furthermore, for coverage purposes, systems operating in frequency bands below 6 GHz are being considered for implementation at base stations and terminals.

[0003] The 3rd Generation Partnership Project (3GPP) NR system improves network spectral efficiency, enabling carriers to provide more data and voice services within a given bandwidth. Therefore, the 3GPP NR system is designed to meet the demands for high-speed data and media transmission in addition to high-capacity voice support. The advantages of the NR system include high throughput, low latency, support for both frequency division duplex (FDD) and time division duplex (TDD) on the same platform, an improved end-user experience, and a simple architecture that reduces operating costs. To further enhance data processing efficiency, the NR system's dynamic TDD can vary the number of orthogonal frequency division multiplexing (OFDM) symbols available for uplink and downlink transmissions based on the data traffic direction of users in the cell. For example, when the cell's downlink traffic exceeds its uplink traffic, the base station can allocate multiple downlink OFDM symbols to a slot (or subframe). Information about the slot configuration must be transmitted to terminals.

[0004] To mitigate the path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, beamforming, massive MIMO (massive MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, hybrid beamforming that combines analog beamforming and digital beamforming, and large scale antenna technologies are being discussed in 5G communication systems. Additionally, to improve the network of the system, 5G communication systems are developing technologies for advanced small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device to device communication (D2D), vehicle to everything communication (V2X), wireless backhaul, non-terrestrial network communication (NTN), moving networks, cooperative communication, coordinated multi-points (CoMP), and interference cancellation.In addition, advanced coding modulation (ACM) methods such as hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), as well as advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) are being developed in 5G systems.

[0005] Meanwhile, the Internet is evolving from a human-centric network where humans create and consume information to the Internet of Things (IoT), where information is exchanged and processed between distributed components such as objects. The Internet of Everything (IoE), which combines IoT technologies with big data processing technologies through connections to cloud servers, is also emerging. To implement the IoT, technological elements such as sensing technology, wireless and wired communication and network infrastructure, service interface technology, and security technology are required. Recently, research is being conducted on technologies such as sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) for connecting objects. In the IoT environment, intelligent IT (Internet technology) services can be provided that collect and analyze data generated from connected objects to create new value for human life. Through the convergence and integration of existing IT (Information Technology) technologies with various industries, the IoT can be applied to areas such as smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0006] Accordingly, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine (M2M), and machine-type communication (MTC) are being implemented using 5G communication techniques such as beamforming, MIMO, and array antennas. Cloud RAN, a big data processing technology described above, is also an example of the convergence of 5G and IoT technologies. Mobile communication systems have traditionally been developed to provide voice services while ensuring user activity.

[0007] However, mobile communication systems are gradually expanding beyond voice to include data services, and have now evolved to the point where they can provide high-speed data services. However, resource shortages and user demand for high-speed services in existing mobile communication systems are driving the need for more advanced systems.

[0008] The purpose of this specification is to provide a method for transmitting a physical downlink channel in a wireless communication system and a device therefor.

[0009] The present specification provides a method for transmitting a physical downlink channel in a wireless communication system.

[0010] A method for receiving a physical downlink control channel (PDCCH) in a wireless communication system, the method being performed by a terminal, comprises the steps of: receiving configuration information for a first control resource set (CORESET) from a base station; receiving configuration information for a second CORESET from the base station; receiving, from the base station, a first PDCCH transmitted on the first CORESET; and receiving, from the base station, a second PDCCH transmitted on the second CORESET, wherein the first PDCCH and the second PDCCH are each repeatedly transmitted from the base station, and first downlink control information (DCI) included in the first PDCCH and second DCI included in the second PDCCH are identical to each other.

[0011] In addition, in the present specification, a method performed by a terminal further includes the steps of: receiving configuration information for a first search space from the base station; and receiving configuration information for a second search space from the base station, wherein the first search space is associated with the first CORESET, the second search space is associated with the second CORESET, the first search space and the second search space are resources in different time domains, and the first PDCCH is received on the first search space and the second PDCCH is received on the second search space.

[0012] In addition, in the present specification, the method performed by the terminal further includes a step of transmitting, to the base station, HARQ-ACK information for one of the first PDCCH and the second PDCCH, wherein the HARQ-ACK information is characterized in that it is HARQ-ACK information for a PDCCH transmitted on a search space having a lower index among the indexes of the first search space and the indexes of the second search space.

[0013] In addition, in the present specification, a method performed by a terminal further includes the steps of: receiving a third PDCCH on a third search space from the base station; and transmitting, to the base station, HARQ_ACK information for any one of the first PDCCH, the second PDCCH, and the third PDCCH, wherein the third PDCCH includes a third DCI different from the first DCI and the second DCI, and when the third search space overlaps with any one of the first search space or the second search space, the HARQ-ACK information is characterized in that it is HARQ-ACK information for a PDCCH transmitted on a search space having a lowest index among the indices of the overlapping search spaces.

[0014] Also, in the present specification, a terminal for receiving a physical downlink control channel (PDCCH) in a wireless communication system includes a transceiver; and a processor for controlling the transceiver, wherein the processor receives configuration information for a first control resource set (CORESET) from a base station, receives configuration information for a second CORESET from the base station, receives a first PDCCH transmitted on the first CORESET from the base station, and receives a second PDCCH transmitted on the second CORESET from the base station, wherein the first PDCCH and the second PDCCH are repeatedly transmitted from the base station, and first downlink control information (DCI) included in the first PDCCH and second DCI included in the second PDCCH are characterized in that they are identical to each other.

[0015] In addition, in the present specification, the processor further includes a step of receiving configuration information for a first search space from the base station and receiving configuration information for a second search space from the base station, wherein the first search space is associated with the first CORESET, the second search space is associated with the second CORESET, the first search space and the second search space are different time domain resources, and the first PDCCH is received on the first search space and the second PDCCH is received on the second search space.

[0016] In addition, in the present specification, the first PDCCH and the second PDCCH are characterized in that they are set to the same aggregation level (AL).

[0017] In addition, in the present specification, the first CORESET and the second CORESET are characterized in that they are resources in different time-frequency domains.

[0018] In addition, in the present specification, the first CORESET and the second CORESET are characterized in that they are resources in the same time-frequency domain.

[0019] In addition, in the present specification, the first PDCCH and the second PDCCH are characterized in that they are included in the same slot and repeatedly transmitted.

[0020] In addition, in the present specification, the first PDCCH and the second PDCCH are characterized in that they are repeatedly transmitted on different slots.

[0021] In addition, in the present specification, the first DCI and the second DCI are each characterized in that they are independently decoded.

[0022] In addition, in the present specification, the first DCI and the second DCI are characterized in that they are combined and decoded with each other.

[0023] In addition, in the present specification, the configuration information for the first search space includes information on the period of the first search space, the configuration information for the second search space includes information on the period of the second search space, and the period of the first search space and the period of the second search space are characterized in that they are the same.

[0024] In addition, in the present specification, the type of the first search space and the type of the second search space are the same, and the type of the first search space and the type of the second search space are characterized in that they are either a common search space or a UE specific search space.

[0025] Also, in the present specification, in a method for transmitting a physical downlink control channel (PDCCH) in a wireless communication system, the method performed by a base station includes the steps of: transmitting configuration information for a first control resource set (CORESET) to a terminal; transmitting configuration information for a second CORESET to the terminal; transmitting a first PDCCH on the first CORESET to the terminal; and transmitting a second PDCCH on the second CORESET to the terminal, wherein the first PDCCH and the second PDCCH are repeatedly transmitted to the terminal, respectively, and first downlink control information (DCI) included in the first PDCCH and second DCI included in the second PDCCH are characterized in that they are identical to each other.

[0026] The purpose of this specification is to improve PDCCH reception reliability by having a terminal receive the same DCI through multiple PDCCHs.

[0027] The effects that can be obtained from this specification are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the description below.

[0028] Figure 1 shows an example of a radio frame structure used in a wireless communication system.

[0029] Figure 2 shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system.

[0030] Figure 3 is a drawing for explaining a physical channel used in a 3GPP system and a general signal transmission method using the physical channel.

[0031] Figures 4a and 4b illustrate SS / PBCH blocks for initial cell access in a 3GPP NR system.

[0032] Figures 5a and 5b illustrate procedures for transmitting control information and control channels in a 3GPP NR system.

[0033] Figure 6 is a diagram showing a CORESET (control resource set) in which a PDCCH (physical downlink control channel) can be transmitted in a 3GPP NR system.

[0034] FIG. 7 is a diagram illustrating a method for setting a PDCCH search space in a 3GPP NR system.

[0035] Figure 8 is a conceptual diagram explaining carrier aggregation.

[0036] Figure 9 is a diagram for explaining single carrier communication and multi-carrier communication.

[0037] Figure 10 is a diagram illustrating an example in which a cross-carrier scheduling technique is applied.

[0038] Figure 11 is a block diagram showing the configuration of a terminal and a base station according to one embodiment of the present invention.

[0039] Figure 12 illustrates scheduling of a physical downlink shared channel according to one embodiment of the present invention.

[0040] Figure 13 illustrates scheduling of a physical uplink control channel according to one embodiment of the present invention.

[0041] FIG. 14 illustrates scheduling of a physical uplink shared channel and a physical uplink control channel according to one embodiment of the present invention.

[0042] FIG. 15 illustrates that PDCCH is repeatedly transmitted in different control resource sets according to one embodiment of the present invention.

[0043] FIG. 16 illustrates that PDCCH is repeatedly transmitted in different search spaces according to one embodiment of the present invention.

[0044] FIG. 17 illustrates that different repetitive PDCCHs overlap in the time-frequency domain according to one embodiment of the present invention.

[0045] FIG. 18 illustrates a problem that occurs when determining a slot in which a physical downlink shared channel is scheduled, according to one embodiment of the present invention.

[0046] FIG. 19 illustrates a problem that occurs when determining a slot in which a physical uplink shared channel and a physical uplink control channel are scheduled according to one embodiment of the present invention.

[0047] FIG. 20 illustrates that slots are determined according to a dynamic slot format indicator according to one embodiment of the present invention.

[0048] Figure 21 illustrates a problem that occurs when a slot is determined according to a dynamic slot format indicator according to one embodiment of the present invention.

[0049] FIG. 22 illustrates that a slot is determined based on a downlink preemption indicator according to one embodiment of the present invention.

[0050] Figure 23 illustrates a problem that occurs when a slot is determined according to a downlink preemption indicator according to one embodiment of the present invention.

[0051] Figure 24 shows a slot determined according to an uplink cancellation indicator according to one embodiment of the present invention.

[0052] Figure 25 illustrates a problem that occurs when determining a slot based on an uplink cancellation indicator.

[0053] FIG. 26 illustrates a method for determining a reference slot according to one embodiment of the present invention.

[0054] FIG. 27 illustrates a method for determining a reference slot according to one embodiment of the present invention.

[0055] Figure 28 illustrates active PDCCH and repetitive PDCCH reception according to one embodiment of the present invention.

[0056] Figure 29 illustrates the configuration of a control resource set according to one embodiment of the present invention.

[0057] Figure 30 illustrates the configuration of a control resource set according to one embodiment of the present invention.

[0058] Figure 31 illustrates a control resource set composed of a basic control resource set according to one embodiment of the present invention.

[0059] Figure 32 illustrates a control resource set consisting of a basic control resource set according to one embodiment of the present invention.

[0060] Figure 33 illustrates a method for designing a control resource set using a basic control resource set according to one embodiment of the present invention.

[0061] FIG. 34 illustrates a method for configuring a control resource set using a basic control resource set according to one embodiment of the present invention.

[0062] FIG. 35 illustrates a method for indexing CCE in a frequency-priority manner according to one embodiment of the present invention.

[0063] FIG. 36 illustrates a method for indexing CCE in a time-first manner according to one embodiment of the present invention.

[0064] FIG. 37 illustrates a PDCCH candidate based on a CCE indexed in a frequency-first manner according to one embodiment of the present invention.

[0065] FIG. 38 illustrates a PDCCH candidate based on a CCE indexed in a time-first manner according to one embodiment of the present invention.

[0066] Figure 39 illustrates that a PDCCH is repeatedly received on a basic control resource set according to one embodiment of the present invention.

[0067] FIG. 40 illustrates a terminal according to one embodiment of the present invention repeatedly receiving PDCCH candidates by applying interleaving to a basic control resource set.

[0068] Figure 41 illustrates that a PDCCH is repeatedly transmitted on multiple search spaces according to one embodiment of the present invention.

[0069] Figure 42 illustrates a PDCCH being transmitted based on a search space and repetition settings according to one embodiment of the present invention.

[0070] FIG. 43 illustrates that a PDCCH is transmitted at different start symbol positions based on a search space and repetition settings according to one embodiment of the present invention.

[0071] Figure 44 illustrates that a PDCCH is transmitted on a plurality of control resource sets according to one embodiment of the present invention.

[0072] Figure 45 is a flowchart showing the transmission of a repetitive PDCCH according to an embodiment of the present invention.

[0073] The terms used in this specification have been selected from widely used and current terms, taking into account the functions of the present invention. However, these terms may vary depending on the intentions of those skilled in the art, customs, or the emergence of new technologies. Furthermore, in certain cases, the applicant may arbitrarily select terms, in which case their meanings will be described in the description of the relevant invention. Therefore, it should be noted that the terms used in this specification should be interpreted based on their substantive meaning and the overall content of this specification, rather than simply their names.

[0074] Throughout the specification, when a component is said to be "connected" to another component, this includes not only the case where the component is "directly connected," but also the case where the component is "electrically connected" with another component intervening therebetween. Furthermore, when a component is said to "include" a particular component, this does not exclude the other component, but rather allows the inclusion of other components, unless specifically stated otherwise. Furthermore, the terms "more than" or "less than" based on a specific threshold may be appropriately replaced with "more than" or "less than", respectively, depending on the embodiment.

[0075] The following technologies can be used in various wireless access systems, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA can be implemented with radio technologies such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA can be implemented with radio technologies such as GSM (Global System for Mobile communications) / GPRS (General Packet Radio Service) / EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented with radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (Evolved UTRA). UTRA is a part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (long term evolution) is a part of E-UMTS (Evolved UMTS) that uses E-UTRA, and LTE-A (Advanced) is an evolved version of 3GPP LTE.3GPP NR (New Radio) is a system designed separately from LTE / LTE-A to support enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC) services, which are requirements of IMT-2020. For clarity, the following description focuses on 3GPP NR, but the technical concepts of the present invention are not limited thereto.

[0076] Unless otherwise specified herein, a base station may include a gNB (next generation node B) defined in 3GPP NR. In addition, unless otherwise specified, a terminal may include a UE (user equipment). Hereinafter, to facilitate understanding of the description, each content is described separately as an embodiment, but each embodiment may be used in combination with each other. In the present disclosure, the configuration of a terminal may refer to a configuration by a base station. Specifically, the base station may transmit a channel or signal to the terminal to set the values ​​of parameters used in the operation of the terminal or in a wireless communication system.

[0077] Figure 1 shows an example of a radio frame structure used in a wireless communication system.

[0078] Referring to Figure 1, the radio frame (or radio frame) used in the 3GPP NR system is 10ms (Δf max N f / 100) * T c ) can have a length of . In addition, a radio frame consists of 10 equally sized subframes (SF). Here, Δf max =480*10 3 Hz, N f =4096, T c =1 / (Δfref *N f,ref ), Δf ref =15*10 3 Hz, N f,ref =2048. Each of the 10 subframes within a radio frame can be numbered from 0 to 9. Each subframe has a length of 1ms and can be composed of one or more slots depending on the subcarrier spacing. More specifically, the subcarrier spacing that can be used in the 3GPP NR system is 15*2. μ kHz. μ is the subcarrier spacing configuration, and μ can have a value of 0 to 4. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz, or 240 kHz can be used as the subcarrier spacing. A 1 ms long subframe is 2 μ It can be composed of slots, where the length of each slot is 2 -μ ms. 2 within one subframe μ The slots of each dog are numbered from 0 to 2 μ - Numbers from 1 to 1 can be assigned. Also, slots within a radio frame are numbered from 0 to 10*2. μ - A number up to 1 may be assigned. Time resources may be distinguished by at least one of a radio frame number (also called a radio frame index), a subframe number (also called a subframe index), and a slot number (or slot index).

[0079] Figure 2 illustrates an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. In particular, Figure 2 illustrates the structure of a resource grid of a 3GPP NR system.

[0080] There is one resource grid per antenna port. Referring to Fig. 2, a slot includes multiple OFDM (orthogonal frequency division multiplexing) symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. An OFDM symbol also means one symbol period. Unless otherwise specified, an OFDM symbol may be simply referred to as a symbol. One RB includes 12 consecutive subcarriers in the frequency domain. Referring to Fig. 2, a signal transmitted in each slot is N size,μ grid,x * N RB sc N subcarriers and slot symb It can be expressed as a resource grid consisting of OFDM symbols. Here, when it is a downlink resource grid, x=DL, and when it is an uplink resource grid, x=UL. N size,μ grid,x represents the number of resource blocks (RBs) according to the subcarrier spacing configuration factor μ (x is DL or UL), and N slot symb represents the number of OFDM symbols in a slot. N RB sc N is the number of subcarriers that constitute one RB. RB sc =12. Depending on the multiple access method, an OFDM symbol may be referred to as a CP-OFDM (cyclic prefix OFDM) symbol or a DFT-S-OFDM (discrete Fourier transform spread OFDM) symbol.

[0081] The number of OFDM symbols included in one slot may vary depending on the length of the CP (cyclic prefix). For example, in the case of a normal CP, one slot may include 14 OFDM symbols, but in the case of an extended CP, one slot may include 12 OFDM symbols. In a specific embodiment, the extended CP may be used only at a 60 kHz subcarrier spacing. In Fig. 2, for convenience of explanation, a case in which one slot consists of 14 OFDM symbols is exemplified, but embodiments of the present invention may be applied in the same manner to slots having a different number of OFDM symbols. Referring to Fig. 2, each OFDM symbol is, in the frequency domain, N size,μ grid,x * N RB sc It contains subcarriers. The types of subcarriers can be divided into data subcarriers for data transmission, reference signal subcarriers for reference signal transmission, and guard bands. The carrier frequency is also called the center frequency (fc).

[0082] One RB is N in the frequency domain. RB sc can be defined by a number of consecutive subcarriers (e.g., 12). For reference, a resource consisting of one OFDM symbol and one subcarrier can be referred to as a resource element (RE) or tone. Therefore, one RB is N slot symb * N RB sc It can be composed of resource elements. Each resource element within the resource grid can be uniquely defined by an index pair (k, l) within one slot. k is from 0 to N in the frequency domain. size,μ grid, x * N RBsc - An index is given from 1, and l is from 0 to N in the time domain. slot symb - It can be an index assigned up to 1.

[0083] For a terminal to receive signals from or transmit signals to a base station, its time / frequency synchronization may need to be aligned with that of the base station. Only when the base station and terminal are synchronized can the terminal determine the time and frequency parameters necessary to accurately demodulate DL signals and transmit UL signals.

[0084] Each symbol of a radio frame operating in time division duplex (TDD) or an unpaired spectrum can be composed of at least one of a downlink symbol (DL symbol), an uplink symbol (UL symbol), or a flexible symbol. A radio frame operating as a downlink carrier in frequency division duplex (FDD) or a paired spectrum can be composed of downlink symbols or flexible symbols, and a radio frame operating as an uplink carrier can be composed of uplink symbols or flexible symbols. Downlink transmission is possible in a downlink symbol but uplink transmission is not possible, and uplink transmission is possible in an uplink symbol but downlink transmission is not possible. A flexible symbol can be determined whether to be used for downlink or uplink depending on a signal.

[0085] Information about the type of each symbol, i.e., information indicating either a downlink symbol, an uplink symbol, or a flexible symbol, may be configured as a cell-specific (or common) radio resource control (RRC) signal. In addition, information about the type of each symbol may additionally be configured as a UE-specific (or dedicated) RRC signal. The base station uses the cell-specific RRC signal to indicate i) the period of the cell-specific slot configuration, ii) the number of slots containing only downlink symbols from the beginning of the period of the cell-specific slot configuration, iii) the number of downlink symbols from the first symbol of the slot immediately following the slot containing only downlink symbols, iv) the number of slots containing only uplink symbols from the end of the period of the cell-specific slot configuration, and v) the number of uplink symbols from the last symbol of the slot immediately preceding the slot containing only uplink symbols. Here, a symbol that is not composed of either an uplink symbol or a downlink symbol is a flexible symbol.

[0086] When information about the symbol type is configured as a terminal-specific RRC signal, the base station can signal whether the flexible symbol is a downlink symbol or an uplink symbol using a cell-specific RRC signal. At this time, the terminal-specific RRC signal cannot change the downlink symbol or uplink symbol configured as the cell-specific RRC signal to a different symbol type. The terminal-specific RRC signal is configured for each slot, and N of the corresponding slot slot symb Number of downlink symbols in the symbol slot, N slot symbThe number of uplink symbols in the symbol can be signaled. At this time, the downlink symbols of the slot can be configured continuously from the first symbol of the slot to the i-th symbol. In addition, the uplink symbols of the slot can be configured continuously from the j-th symbol of the slot to the last symbol (where, i <j). 슬롯에서 상향링크 심볼과 하향링크 심볼 어느 것으로도 구성되지 않은 심볼은 플랙서블 심볼이다.

[0087] The type of symbol composed of the above RRC signal can be referred to as a semi-static DL / UL configuration. In the semi-static DL / UL configuration composed of the above RRC signal, a flexible symbol can be indicated as a downlink symbol, an uplink symbol, or a flexible symbol through dynamic SFI (slot format information) transmitted on a physical downlink control channel (PDCCH). In this case, the downlink symbol or uplink symbol composed of the RRC signal is not changed to another symbol type. Table 1 shows examples of dynamic SFI that a base station can indicate to a terminal.

[0088]

[0089] In Table 1, D represents a downlink symbol, U represents an uplink symbol, and X represents a flexible symbol. As shown in Table 1, up to two DL / UL switchings can be allowed within one slot.

[0090] FIG. 3 is a diagram illustrating a physical channel used in a 3GPP system (e.g., NR) and a general signal transmission method using the physical channel.

[0091] When the terminal powers up or enters a new cell, the terminal performs an initial cell search operation (S101). Specifically, the terminal can synchronize with the base station during the initial cell search. To this end, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and obtain information such as a cell index. Thereafter, the terminal can receive a physical broadcast channel from the base station to obtain broadcast information within the cell.

[0092] A terminal that has completed initial cell search can obtain more specific system information than the system information obtained through initial cell search by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried in the PDCCH (S102). The system information received by the terminal here is cell-common system information for the terminal to operate properly in the physical layer of the RRC (Radio Resource Control, RRC), and is referred to as remaining system information or system information block (SIB) 1.

[0093] When a terminal accesses a base station for the first time or there are no radio resources for signal transmission (when the terminal is in RRC_IDLE mode), the terminal may perform a random access procedure for the base station (steps S103 to S106). First, the terminal transmits a preamble through a physical random access channel (PRACH) (S103) and may receive a response message to the preamble from the base station through a PDCCH and a corresponding PDSCH (S104). When a valid random access response message is received by the terminal, the terminal transmits data, including its identifier, to the base station through a physical uplink shared channel (PUSCH) indicated in an uplink grant transmitted from the base station through the PDCCH (S105). Next, the terminal waits for reception of the PDCCH as an instruction from the base station to resolve collisions. When the terminal successfully receives the PDCCH through its identifier (S106), the random access procedure is terminated. During the random access process, the terminal can obtain terminal-specific system information required for proper operation from the RRC layer to the physical layer. Once the terminal obtains terminal-specific system information from the RRC layer, the terminal enters RRC connected mode (RRC_CONNECTED mode).

[0094] The RRC layer is used to generate and manage messages for control between terminals and the Radio Access Network (RAN). More specifically, the base station and terminals can perform broadcasting of cell system information required for all terminals in the cell, management of delivery of paging messages, mobility management and handover, terminal measurement reporting and control thereof, terminal capability management, and storage management including base station management in the RRC layer. In general, since the update of a signal transmitted in the RRC layer (hereinafter, “RRC signal”) is longer than the transmission / reception cycle (i.e., transmission time interval, TTI) in the physical layer, the RRC signal can be maintained without change for a long period.

[0095] After the procedure described above, the terminal can perform the general uplink / downlink signal transmission procedure of receiving PDCCH / PDSCH (S107) and transmitting physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) (S108). In particular, the terminal can receive downlink control information (DCI) through the PDCCH. The DCI can include control information such as resource allocation information for the terminal. In addition, the format of the DCI can vary depending on the purpose of use. The uplink control information (UCI) that the terminal transmits to the base station through the uplink can include downlink / uplink ACK / NACK signals, channel quality indicator (CQI), precoding matrix index (PMI), rank indicator (RI), etc. Here, the CQI, PMI, and RI can be included in channel state information (CSI). In the case of a 3GPP NR system, the terminal can transmit control information such as the HARQ-ACK and CSI described above through PUSCH and / or PUCCH.

[0096] Figures 4a and 4b illustrate SS / PBCH blocks for initial cell access in a 3GPP NR system.

[0097] When a terminal is powered on or attempts to connect to a new cell, it can acquire time and frequency synchronization with the cell and perform an initial cell search process. During the cell search process, the terminal obtains the physical cell identity N of the cell. cell IDcan be detected. To this end, the terminal can synchronize with the base station by receiving synchronization signals, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), from the base station. At this time, the terminal can obtain information such as a cell identifier (ID).

[0098] Referring to Fig. 4a, the synchronization signal (SS) will be described in more detail. The synchronization signal can be divided into PSS and SSS. PSS can be used to obtain time domain synchronization such as OFDM symbol synchronization, slot synchronization, and / or frequency domain synchronization. SSS can be used to obtain frame synchronization and cell group ID. Referring to Fig. 4a and Table 2, an SS / PBCH block can be composed of 20 consecutive RBs (= 240 subcarriers) in the frequency axis and 4 consecutive OFDM symbols in the time axis. At this time, in the SS / PBCH block, the PSS is transmitted through the 56th to 182nd subcarriers in the first OFDM symbol, and the SSS is transmitted through the 56th to 182nd subcarriers in the third OFDM symbol. Here, the lowest subcarrier index of the SS / PBCH block is numbered from 0. In the first OFDM symbol where PSS is transmitted, the base station does not transmit signals through the remaining subcarriers, i.e., subcarriers 0 to 55 and 183 to 239. Furthermore, in the third OFDM symbol where SSS is transmitted, the base station does not transmit signals through subcarriers 48 to 55 and 183 to 191. The base station transmits the PBCH (physical broadcast channel) through the remaining REs in the SS / PBCH block, excluding the above signals.

[0099]

[0100] The SS can be grouped into 336 physical-layer cell-identifier groups, each group containing three unique identifiers, such that each physical-layer cell ID is part of only one physical-layer cell-identifier group, for a total of 1008 unique physical-layer cell IDs through a combination of three PSSs and SSSs. Therefore, the physical-layer cell ID N cell ID = 3N (1) ID + N (2) ID An index N in the range 0 to 335 representing a group of physical-layer cell identifiers. (1) ID and an index N from 0 to 2 representing the physical-layer identifier within the physical-layer cell-identifier group. (2) ID can be uniquely defined by. The terminal can detect the PSS to identify one of three unique physical-layer identifiers. In addition, the terminal can detect the SSS to identify one of 336 physical-layer cell IDs associated with the physical-layer identifier. At this time, the sequence d of the PSS PSS (n) is as follows.

[0101]

[0102] Here, And,

[0103] is given as

[0104] Also, the sequence d of SSS SSS (n) is as follows.

[0105]

[0106] Here, And,

[0107] is given as

[0108] A 10ms long radio frame can be divided into two half frames each of 5ms long. Referring to Fig. 4b, the slots in which SS / PBCH blocks are transmitted within each half frame are described. The slots in which SS / PBCH blocks are transmitted can be any one of Cases A, B, C, D, and E. In Case A, the subcarrier spacing is 15kHz, and the starting point of the SS / PBCH block is the {2, 8} + 14*nth symbol. At this time, n can be 0 or 1 for carrier frequencies below 3GHz. In addition, n can be 0, 1, 2, or 3 for carrier frequencies exceeding 3GHz and below 6GHz. In Case B, the subcarrier spacing is 30kHz, and the starting point of the SS / PBCH block is the {4, 8, 16, 20} + 28*nth symbol. At this time, n can be 0 for carrier frequencies below 3GHz. Also, n can be 0, 1 at a carrier frequency exceeding 3 GHz and below 6 GHz. In case C, the subcarrier spacing is 30 kHz, and the starting point of the SS / PBCH block is the {2, 8} + 14*nth symbol. At this time, n can be 0, 1 at a carrier frequency below 3 GHz. Also, n can be 0, 1, 2, 3 at a carrier frequency exceeding 3 GHz and below 6 GHz. In case D, the subcarrier spacing is 120 kHz, and the starting point of the SS / PBCH block is the {4, 8, 16, 20} + 28*nth symbol. At this time, n can be 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 at a carrier frequency above 6 GHz. In Case E, the subcarrier spacing is 240 kHz, and the starting point of the SS / PBCH block is {8, 12, 16, 20, 32, 36, 40, 44} + 56*nth symbol. At this time, n can be 0, 1, 2, 3, 5, 6, 7, or 8 for carrier frequencies above 6 GHz.

[0109] Figures 5a and 5b illustrate a procedure for transmitting control information and a control channel in a 3GPP NR system. Referring to Figure 5a, a base station may add a CRC (cyclic redundancy check) masked (e.g., XOR operation) with a radio network temporary identifier (RNTI) to control information (e.g., downlink control information, DCI) (S202). The base station may scramble the CRC with an RNTI value determined according to the purpose / target of each control information. A common RNTI used by one or more terminals may include at least one of a system information RNTI (SI-RNTI), a paging RNTI (P-RNTI), a random access RNTI (RA-RNTI), and a transmit power control RNTI (TPC-RNTI). In addition, a terminal-specific RNTI may include at least one of a cell temporary RNTI (C-RNTI) and a CS-RNTI. Afterwards, the base station can perform rate matching according to the amount of resource(s) used for PDCCH transmission after performing channel encoding (e.g., polar coding) (S204). Afterwards, the base station can multiplex DCI(s) based on a PDCCH structure based on CCE (control channel element) (S208). In addition, the base station can apply additional processes such as scrambling, modulation (e.g., QPSK), and interleaving (S210) to the multiplexed DCI(s) and then map them to resources to be transmitted. CCE is a basic resource unit for PDCCH, and one CCE can be composed of multiple (e.g., 6) REGs (resource element groups). One REG can be composed of multiple (e.g., 12) REs.The number of CCEs used for a single PDCCH can be defined as an aggregation level. In a 3GPP NR system, aggregation levels of 1, 2, 4, 8, or 16 can be used. Figure 5b is a diagram regarding CCE aggregation levels and PDCCH multiplexing, showing the types of CCE aggregation levels used for a single PDCCH and the CCE(s) transmitted in the control domain accordingly.

[0110] Figure 6 is a diagram showing a CORESET (control resource set) in which a PDCCH (physical downlink control channel) can be transmitted in a 3GPP NR system.

[0111] A CORESET is a time-frequency resource where the PDCCH, a control signal for a terminal, is transmitted. Furthermore, a search space, described below, can be mapped to a single CORESET. Therefore, rather than monitoring the entire frequency band for PDCCH reception, a terminal can monitor the time-frequency domain designated by the CORESET and decode the PDCCH mapped to the CORESET. A base station can configure one or more CORESETs for each cell for the terminal. A CORESET can consist of up to three consecutive symbols along the time axis. Furthermore, a CORESET can be configured in units of six consecutive PRBs along the frequency axis. In the embodiment of FIG. 5, CORESET#1 consists of consecutive PRBs, and CORESET#2 and CORESET#3 consist of non-consecutive PRBs. A CORESET can be located in any symbol within a slot. For example, in the embodiment of FIG. 5, CORESET#1 starts at the first symbol of the slot, CORESET#2 starts at the fifth symbol of the slot, and CORESET#9 starts at the ninth symbol of the slot.

[0112] FIG. 7 is a diagram illustrating a method for setting a PDCCH search space in a 3GPP NR system.

[0113] In order to transmit a PDCCH to a terminal, each CORESET may have at least one search space. In an embodiment of the present invention, the search space is a set of all time-frequency resources (hereinafter, PDCCH candidates) on which the PDCCH of the terminal can be transmitted. The search space may include a common search space that 3GPP NR terminals must commonly search and a terminal-specific or UE-specific search space that a specific terminal must search. In the common search space, a PDCCH that is commonly set for all terminals in a cell belonging to the same base station can be monitored. In addition, a terminal-specific search space may be set for each terminal so that the PDCCH allocated to each terminal can be monitored at different search space locations depending on the terminal. In the case of a terminal-specific search space, the search spaces between terminals may be allocated to partially overlap due to the limited control region to which the PDCCH can be allocated. Monitoring PDCCHs involves blindly decoding PDCCH candidates within the search space. Successful blind decoding is referred to as "successful detection / reception of the PDCCH." Failure to do so is referred to as "non-detection / non-reception of the PDCCH," or "non-successful detection / reception."

[0114] For convenience of explanation, a PDCCH scrambled with a group common (GC) RNTI that one or more terminals already know in order to transmit downlink control information to one or more terminals is referred to as a group common (GC) PDCCH or common PDCCH. In addition, a PDCCH scrambled with a terminal-specific RNTI that a specific terminal already knows in order to transmit uplink scheduling information or downlink scheduling information to a specific terminal is referred to as a terminal-specific PDCCH. The common PDCCH may be included in a common search space, and the terminal-specific PDCCH may be included in either the common search space or the terminal-specific PDCCH.

[0115] The base station can inform each terminal or terminal group of information related to resource allocation of the transmission channel, PCH (paging channel) and DL-SCH (downlink-shared channel) (i.e., DL Grant) or information related to resource allocation of UL-SCH (uplink-shared channel) and HARQ (hybrid automatic repeat request) (i.e., UL Grant) through PDCCH. The base station can transmit PCH transport blocks and DL-SCH transport blocks through PDSCH. The base station can transmit data excluding specific control information or specific service data through PDSCH. In addition, the terminal can receive data excluding specific control information or specific service data through PDSCH.

[0116] The base station can transmit information on the PDCCH, including information about which terminal (one or more terminals) the PDSCH data is transmitted to and how the corresponding terminal should receive and decode the PDSCH data. For example, assume that the DCI transmitted through a specific PDCCH is CRC-masked with an RNTI called "A", and that the DCI indicates that the PDSCH is allocated to a radio resource (e.g., frequency location) called "B", and indicates transmission format information (e.g., transmission block size, modulation method, coding information, etc.) called "C". The terminal monitors the PDCCH using the RNTI information it has. In this case, if there is a terminal that blindly decodes the PDCCH using the "A" RNTI, the terminal receives the PDCCH and, based on the information in the received PDCCH, receives the PDSCH indicated by "B" and "C".

[0117] Table 3 shows an example of a physical uplink control channel (PUCCH) used in a wireless communication system.

[0118]

[0119] PUCCH can be used to transmit the following uplink control information (UCI):

[0120] - SR (Scheduling Request): Information used to request uplink UL-SCH resources.

[0121] - HARQ-ACK: This is a response to the PDCCH (indicating DL SPS release) and / or a response to a downlink transport block (TB) on the PDSCH. HARQ-ACK indicates whether the information transmitted through the PDCCH or PDSCH was successfully received. The HARQ-ACK response includes positive ACK (simply, ACK), negative ACK (hereinafter, NACK), Discontinuous Transmission (DTX), or NACK / DTX. Here, the term HARQ-ACK is used interchangeably with HARQ-ACK / NACK and ACK / NACK. In general, ACK can be expressed with bit value 1, and NACK can be expressed with bit value 0.

[0122] - CSI (Channel State Information): This is feedback information for the downlink channel. It is generated by the terminal based on the CSI-RS (Reference Signal) transmitted by the base station. MIMO (Multiple Input Multiple Output)-related feedback information includes the RI (Rank Indicator) and PMI (Precoding Matrix Indicator). Depending on the information it represents, CSI can be divided into CSI Part 1 and CSI Part 2.

[0123] In 3GPP NR systems, five PUCCH formats can be used to support various service scenarios, channel environments, and frame structures.

[0124] PUCCH format 0 is a format that can transmit 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 0 can be transmitted through 1 or 2 OFDM symbols in the time axis and 1 PRB in the frequency axis. When PUCCH format 0 is transmitted through two OFDM symbols, the same sequence can be transmitted in different RBs in the two symbols. In this case, the sequence can be a sequence cyclically shifted (CS) from the base sequence used in PUCCH format 0. Through this, the terminal can obtain frequency diversity gain. Specifically, the terminal can receive M bit Beat UCI (M bit = 1 or 2) depending on the cyclic shift (CS) value m cs can be determined. In addition, a base sequence of length 12 is given with a CS value m cs A cyclically shifted sequence based on M can be transmitted by mapping it to 12 REs of 1 OFDM symbol and 1 RB. The number of cyclic shifts available to the terminal is 12, and M bit = 1, 1-bit UCI 0 and 1 can be mapped to two cyclically shifted sequences, each with a cyclic shift value difference of 6. In addition, M bit = 2, 2-bit UCI 00, 01, 11, 10 can be mapped to four cyclically shifted sequences, each with a cyclic shift value difference of 3.

[0125] PUCCH format 1 can carry 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 1 can be transmitted through consecutive OFDM symbols in the time axis and 1 PRB in the frequency axis. Here, the number of OFDM symbols occupied by PUCCH format 1 can be one of 4 to 14. More specifically, M bit= 1 UCI can be modulated with BPSK. The terminal is M bit =2 UCI can be modulated with QPSK (quadrature phase shift keying). A signal is obtained by multiplying a modulated complex valued symbol d(0) by a sequence of length 12. At this time, the sequence may be a base sequence used in PUCCH format 0. The terminal transmits the obtained signal by spreading it with a time-domain OCC (orthogonal cover code) in the even-numbered OFDM symbols to which PUCCH format 1 is assigned. In PUCCH format 1, the maximum number of different terminals multiplexed into the same RB is determined according to the length of the OCC used. A demodulation reference signal (DMRS) can be mapped by spreading it with the OCC in the odd-numbered OFDM symbols of PUCCH format 1.

[0126] PUCCH format 2 can carry UCI exceeding 2 bits. PUCCH format 2 can be transmitted through 1 or 2 OFDM symbols in the time axis and 1 or multiple RBs in the frequency axis. When PUCCH format 2 is transmitted through 2 OFDM symbols, the same sequence can be transmitted through different RBs in the 2 OFDM symbols. Here, the sequence is a plurality of modulated complex symbols d(0), … , d(M symbol -1) can be. Here, M symbol Silver M bit / 2 can be used. This allows the terminal to obtain frequency diversity gain. More specifically, M bit Beat UCI (M bit >2) is bit-level scrambled, QPSK modulated and mapped to RB(s) of one or two OFDM symbol(s), where the number of RB(s) can be between 1 and 16.

[0127] PUCCH format 3 or PUCCH format 4 can carry UCI exceeding 2 bits. PUCCH format 3 or PUCCH format 4 can be transmitted through consecutive OFDM symbols in the time axis and one PRB in the frequency axis. The number of OFDM symbols occupied by PUCCH format 3 or PUCCH format 4 can be one of 4 to 14. Specifically, the terminal can transmit M bit Beat UCI (M bit >2) is modulated with π / 2-BPSK (Binary Phase Shift Keying) or QPSK to produce complex symbols d(0)~d(M symb -1) can be generated. Here, using π / 2-BPSK, M symb =M bit And, if QPSK is used, M symb =M bit / 2. The terminal may not apply block-wise spreading to PUCCH format 3. However, the terminal may apply block-wise spreading to one RB (i.e., 12 subcarriers) using PreDFT-OCC of length 12 so that PUCCH format 4 can have a multiplexing capacity of 2 or 4. The terminal may transmit the spread signal by transmitting precoding (or DFT-precoding) the spread signal and mapping it to each RE.

[0128] At this time, the number of RBs occupied by PUCCH format 2, PUCCH format 3, or PUCCH format 4 can be determined according to the length of UCI transmitted by the terminal and the maximum code rate. If the terminal uses PUCCH format 2, the terminal can transmit HARQ-ACK information and CSI information together through PUCCH. If the number of RBs that the terminal can transmit is greater than the maximum number of RBs available for PUCCH format 2, PUCCH format 3, or PUCCH format 4, the terminal can transmit only the remaining UCI information without transmitting some UCI information according to the priority of the UCI information.

[0129] PUCCH format 1, PUCCH format 3, or PUCCH format 4 can be configured via RRC signaling to indicate frequency hopping within a slot. When frequency hopping is configured, the index of the RB to be frequency hopped can be configured via RRC signaling. When PUCCH format 1, PUCCH format 3, or PUCCH format 4 is transmitted over N OFDM symbols in the time axis, the first hop can have floor(N / 2) OFDM symbols and the second hop can have ceil(N / 2) OFDM symbols.

[0130] PUCCH format 1, PUCCH format 3, or PUCCH format 4 can be configured to be repeatedly transmitted in multiple slots. In this case, the number K of slots in which the PUCCH is repeatedly transmitted can be configured by an RRC signal. The repeatedly transmitted PUCCH must start from the same OFDM symbol in each slot and have the same length. If any OFDM symbol in the slot in which the UE must transmit the PUCCH is indicated as a DL symbol by an RRC signal, the UE may not transmit the PUCCH in that slot and postpone transmission to the next slot.

[0131] Meanwhile, in the 3GPP NR system, a terminal can perform transmission and reception using a bandwidth that is smaller than or equal to the bandwidth of a carrier (or cell). To this end, the terminal can be configured with a bandwidth part (BWP) consisting of a continuous bandwidth of a portion of the carrier's bandwidth. A terminal operating in TDD or an unpaired spectrum can be configured with up to four DL / UL BWP pairs per carrier (or cell). In addition, the terminal can activate one DL / UL BWP pair. A terminal operating in FDD or a paired spectrum can be configured with up to four DL BWPs per downlink carrier (or cell) and up to four UL BWPs per uplink carrier (or cell). The terminal can activate one DL BWP and one UL BWP per carrier (or cell). A terminal may not receive or transmit on time-frequency resources other than the activated BWP. The activated BWP may be referred to as an active BWP.

[0132] A base station can indicate an activated BWP among the configured BWPs of a terminal through downlink control information (DCI). The BWP indicated through the DCI is activated, and other configured BWP(s) are deactivated. In a carrier (or cell) operating in TDD, the base station can include a bandwidth part indicator (BPI) indicating an activated BWP in the DCI scheduling PDSCH or PUSCH to change the DL / UL BWP pair of the terminal. The terminal can receive the DCI scheduling PDSCH or PUSCH and identify the activated DL / UL BWP pair based on the BPI. In a downlink carrier (or cell) operating in FDD, the base station can include a BPI indicating an activated BWP in the DCI scheduling PDSCH to change the DL BWP of the terminal. For an uplink carrier (or cell) operating in FDD, the base station may include a BPI indicating the BWP to be activated in the DCI scheduling the PUSCH to change the UL BWP of the terminal.

[0133] Figure 8 is a conceptual diagram explaining carrier aggregation.

[0134] Carrier aggregation refers to a method in which a wireless communication system utilizes multiple frequency blocks or (logically speaking) cells composed of uplink resources (or component carriers) and / or downlink resources (or component carriers) as a single large logical frequency band, so that the terminal can utilize a wider frequency band. A single component carrier may also be referred to as a PCell (Primary cell), SCell (Secondary Cell), or PScell ​​(Primary SCell). However, for convenience of explanation, the term "component carrier" will be used hereafter.

[0135] Referring to FIG. 8, as an example of a 3GPP NR system, the entire system bandwidth may include up to 16 component carriers, and each component carrier may have a bandwidth of up to 400 MHz. A component carrier may include one or more physically contiguous subcarriers. Although FIG. 8 illustrates that each component carrier has the same bandwidth, this is merely an example, and each component carrier may have a different bandwidth. In addition, although each component carrier is illustrated as being adjacent to each other on the frequency axis, the drawing is illustrated in a logical concept, and each component carrier may be physically adjacent to each other or may be spaced apart from each other.

[0136] Different center frequencies may be used for each component carrier. Furthermore, a common center frequency may be used for physically adjacent component carriers. In the embodiment of FIG. 8, assuming that all component carriers are physically adjacent, center frequency A may be used for all component carriers. Furthermore, assuming that each component carrier is not physically adjacent, center frequency A and center frequency B may be used for each component carrier.

[0137] When the overall system bandwidth is expanded by carrier aggregation, the frequency band used for communication with each terminal can be defined in component carrier units. Terminal A can use the entire system bandwidth of 100 MHz and performs communication using all five component carriers. Terminals B1 to B5 can use only a 20 MHz bandwidth and perform communication using one component carrier. Terminals C1 and C2 can use a 40 MHz bandwidth and perform communication using two component carriers each. The two component carriers may or may not be logically / physically adjacent. The embodiment of FIG. 8 illustrates a case where terminal C1 uses two non-adjacent component carriers and terminal C2 uses two adjacent component carriers.

[0138] Figure 9 is a diagram for explaining single-carrier communication and multi-carrier communication. In particular, Figure 9 (a) illustrates the subframe structure of a single carrier, and Figure 9 (b) illustrates the subframe structure of a multi-carrier.

[0139] Referring to (a) of Fig. 9, a typical wireless communication system can perform data transmission or reception through one DL band and one corresponding UL band in the case of FDD mode. In another specific embodiment, the wireless communication system can divide a radio frame into an uplink time unit and a downlink time unit in the time domain in the case of TDD mode, and perform data transmission or reception through the uplink / downlink time units. Referring to (b) of Fig. 9, three 20MHz component carriers (CCs) each in the UL and DL can be aggregated to support a bandwidth of 60MHz. Each CC can be adjacent or non-adjacent in the frequency domain. For convenience, Fig. 9 (b) illustrates a case where the bandwidth of the UL CC and the bandwidth of the DL CC are both the same and symmetrical, but the bandwidth of each CC can be determined independently. In addition, asymmetric carrier aggregation is also possible, where the number of UL CCs and the number of DL CCs are different. A DL / UL CC allocated / configured to a specific terminal through RRC can be called the serving DL / UL CC of the specific terminal.

[0140] A base station can communicate with a terminal by activating some or all of the serving CCs of the terminal or deactivating some CCs. The base station can change the CCs to be activated / deactivated and the number of CCs to be activated / deactivated. When the base station allocates available CCs to the terminal in a cell-specific or terminal-specific manner, at least one of the assigned CCs may not be deactivated unless the CC allocation to the terminal is completely reconfigured or the terminal performs a handover. One CC that is not deactivated for the terminal is called a primary CC (PCC) or PCell (primary cell), and the CC that the base station can freely activate / deactivate is called a secondary CC (SCC) or SCell (secondary cell).

[0141] Meanwhile, 3GPP NR uses the concept of a cell to manage radio resources. A cell is defined as a combination of downlink and uplink resources, i.e., a combination of a DL CC and an UL CC. A cell can consist of only DL resources or a combination of DL and UL resources. When carrier aggregation is supported, the linkage between the carrier frequency of the DL resources (or DL ​​CC) and the carrier frequency of the UL resources (or UL CC) can be indicated by system information. The carrier frequency refers to the center frequency of each cell or CC. The cell corresponding to the PCC is referred to as a PCell, and the cell corresponding to the SCC is referred to as an SCell. The carrier corresponding to the PCell in the downlink is a DL PCC, and the carrier corresponding to the PCell in the uplink is a UL PCC. Similarly, the carrier corresponding to the SCell in the downlink is a DL SCC, and the carrier corresponding to the SCell in the uplink is a UL SCC. Depending on the UE's capabilities, the serving cell(s) may consist of one PCell and zero or more SCells. For UEs in RRC_CONNECTED state but without carrier aggregation configured or supporting carrier aggregation, there is only one serving cell consisting of only PCell.

[0142] As mentioned above, the term "cell" used in carrier aggregation is distinct from the term "cell" which refers to a certain geographic area where communication services are provided by a single base station or a single antenna group. That is, a single component carrier may also be referred to as a scheduling cell, a scheduled cell, a PCell (Primary cell), a SCell (Secondary Cell), or a PScell ​​(Primary SCell). However, in order to distinguish between a cell referring to a certain geographic area and a cell of carrier aggregation, the present invention refers to a cell of carrier aggregation as a CC, and a cell of a geographic area as a cell.

[0143] FIG. 10 is a diagram illustrating an example of a cross-carrier scheduling technique. When cross-carrier scheduling is configured, a control channel transmitted through a first CC can schedule a data channel transmitted through the first or second CC using a carrier indicator field (CIF). The CIF is included in the DCI. In other words, a scheduling cell is configured, and a DL grant / UL grant transmitted in the PDCCH region of the scheduling cell schedules the PDSCH / PUSCH of the scheduled cell. In other words, a search region for multiple component carriers exists in the PDCCH region of the scheduling cell. The PCell is basically a scheduling cell, and a specific SCell can be designated as a scheduling cell by a higher layer.

[0144] In the embodiment of FIG. 10, it is assumed that three DL CCs are merged. Here, DL component carrier #0 is assumed to be a DL PCC (or PCell), and DL component carrier #1 and DL component carrier #2 are assumed to be DL SCCs (or SCells). In addition, it is assumed that the DL PCC is configured as a PDCCH monitoring CC. If cross-carrier scheduling is not configured by UE-specific (or UE-group-specific or cell-specific) upper layer signaling, CIF is disabled, and each DL CC can transmit only a PDCCH that schedules its own PDSCH without a CIF according to the NR PDCCH rule (non-cross-carrier scheduling, self-carrier scheduling). On the other hand, when cross-carrier scheduling is configured by terminal-specific (or terminal-group-specific or cell-specific) upper layer signaling, CIF is enabled, and a specific CC (e.g., DL PCC) can transmit not only the PDCCH scheduling the PDSCH of DL CC A but also the PDCCH scheduling the PDSCH of other CCs using CIF (cross-carrier scheduling). On the other hand, PDCCH is not transmitted in other DL CCs. Therefore, depending on whether cross-carrier scheduling is configured for the terminal, the terminal monitors the PDCCH that does not include CIF to receive a self-carrier scheduled PDSCH, or monitors the PDCCH that includes CIF to receive a cross-carrier scheduled PDSCH.

[0145] Meanwhile, although FIGS. 9 and 10 illustrate the subframe structure of a 3GPP LTE-A system, the same or similar configuration can also be applied to a 3GPP NR system. However, in a 3GPP NR system, the subframes of FIGS. 9 and 10 can be replaced with slots.

[0146] Figure 11 is a block diagram showing the configuration of a terminal and a base station according to one embodiment of the present invention.

[0147] In embodiments of the present invention, a terminal may be implemented as various types of wireless communication devices or computing devices that ensure portability and mobility. The terminal may be referred to as a UE (User Equipment), STA (Station), MS (Mobile Subscriber), etc. In addition, in embodiments of the present invention, a base station may control and manage cells (e.g., macro cells, femto cells, pico cells, etc.) corresponding to a service area, and perform functions such as signal transmission, channel designation, channel monitoring, self-diagnosis, and relay. The base station may be referred to as a gNB (next generation NodeB) or an AP (access point).

[0148] As illustrated, a terminal (100) according to one embodiment of the present invention may include a processor (110), a communication module (120), a memory (130), a user interface unit (140), and a display unit (150).

[0149] First, the processor (110) can execute various commands or programs and process data within the terminal (100). In addition, the processor (110) can control the overall operation of the terminal (100), including each unit, and control data transmission and reception between the units. Here, the processor (110) can be configured to perform operations according to the embodiments described in the present invention. For example, the processor (110) can receive slot configuration information, determine the slot configuration based on the information, and perform communication according to the determined slot configuration.

[0150] Next, the communication module (120) may be an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module (120) may be equipped with a plurality of network interface cards (NICs) in built-in or external form, such as a cellular communication interface card (121, 122) and an unlicensed band communication interface card (123). Although the communication module (120) is illustrated as an integrated module in the drawing, each network interface card may be independently arranged depending on the circuit configuration or purpose, unlike the drawing.

[0151] The cellular communication interface card (121) can transmit and receive wireless signals with at least one of a base station (200), an external device, and a server using a mobile communication network, and can provide a cellular communication service by a first frequency band based on a command of the processor (110). According to one embodiment, the cellular communication interface card (121) can include at least one NIC module that uses a frequency band lower than 6 GHz. At least one NIC module of the cellular communication interface card (121) can independently perform cellular communication with at least one of the base station (200), an external device, and a server according to a cellular communication standard or protocol of a frequency band lower than 6 GHz supported by the corresponding NIC module.

[0152] The cellular communication interface card (122) may transmit and receive wireless signals with at least one of a base station (200), an external device, and a server using a mobile communication network, and may provide a cellular communication service by a second frequency band based on a command of the processor (110). According to one embodiment, the cellular communication interface card (122) may include at least one NIC module that uses a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card (122) may independently perform cellular communication with at least one of the base station (200), an external device, and a server according to a cellular communication standard or protocol of a frequency band of 6 GHz or higher supported by the corresponding NIC module.

[0153] The unlicensed band communication interface card (123) transmits and receives wireless signals with at least one of a base station (200), an external device, and a server using the third frequency band, which is an unlicensed band, and provides an unlicensed band communication service based on a command of the processor (110). The unlicensed band communication interface card (123) may include at least one NIC module that uses an unlicensed band. For example, the unlicensed band may be a band of 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or higher. At least one NIC module of the unlicensed band communication interface card (123) may independently or dependently perform wireless communication with at least one of the base station (200), an external device, and a server according to an unlicensed band communication standard or protocol of a frequency band supported by the corresponding NIC module.

[0154] Next, the memory (130) stores a control program used in the terminal (100) and various data corresponding thereto. This control program may include a predetermined program required for the terminal (100) to perform wireless communication with at least one of a base station (200), an external device, and a server.

[0155] Next, the user interface (140) includes various types of input / output means provided in the terminal (100). That is, the user interface (140) can receive user input using various input means, and the processor (110) can control the terminal (100) based on the received user input. In addition, the user interface (140) can perform output based on a command of the processor (110) using various output means.

[0156] Next, the display unit (150) outputs various images on the display screen. The display unit (150) can output various display objects, such as content executed by the processor (110) or a user interface based on the control commands of the processor (110).

[0157] Additionally, a base station (200) according to one embodiment of the present invention may include a processor (210), a communication module (220), and a memory (230).

[0158] First, the processor (210) can execute various commands or programs and process data within the base station (200). In addition, the processor (210) can control the overall operation of the base station (200), including each unit, and control data transmission and reception between the units. Here, the processor (210) can be configured to perform operations according to the embodiments described in the present invention. For example, the processor (210) can signal slot configuration information and perform communication according to the signaled slot configuration.

[0159] Next, the communication module (220) may be an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module (220) may be equipped with multiple network interface cards, such as cellular communication interface cards (221, 222) and unlicensed band communication interface cards (223), in built-in or external form. Although the communication module (220) is depicted as an integrated module in the drawing, each network interface card may be independently arranged depending on the circuit configuration or purpose, unlike the drawing.

[0160] The cellular communication interface card (221) can transmit and receive wireless signals with at least one of the terminal (100), external device, and server described above using a mobile communication network, and can provide a cellular communication service using a first frequency band based on a command of the processor (210). According to one embodiment, the cellular communication interface card (221) can include at least one NIC module using a frequency band lower than 6 GHz. At least one NIC module of the cellular communication interface card (221) can independently perform cellular communication with at least one of the terminal (100), external device, and server according to a cellular communication standard or protocol of a frequency band lower than 6 GHz supported by the corresponding NIC module.

[0161] The cellular communication interface card (222) may transmit and receive wireless signals with at least one of a terminal (100), an external device, and a server using a mobile communication network, and may provide a cellular communication service using a second frequency band based on a command of the processor (210). According to one embodiment, the cellular communication interface card (222) may include at least one NIC module using a frequency band of 6 GHz or higher. At least one NIC module of the cellular communication interface card (222) may independently perform cellular communication with at least one of the terminal (100), an external device, and a server according to a cellular communication standard or protocol of a frequency band of 6 GHz or higher supported by the corresponding NIC module.

[0162] The unlicensed band communication interface card (223) transmits and receives wireless signals with at least one of a terminal (100), an external device, and a server using the third frequency band, which is an unlicensed band, and provides an unlicensed band communication service based on a command of the processor (210). The unlicensed band communication interface card (223) may include at least one NIC module that uses an unlicensed band. For example, the unlicensed band may be a band of 2.4 GHz, 5 GHz, 6 GHz, 7 GHz, or 52.6 GHz or higher. At least one NIC module of the unlicensed band communication interface card (223) may independently or dependently perform wireless communication with at least one of the terminal (100), an external device, and a server according to an unlicensed band communication standard or protocol of a frequency band supported by the corresponding NIC module.

[0163] The terminal (100) and base station (200) illustrated in FIG. 11 are block diagrams according to one embodiment of the present invention, and the blocks shown separately are logically distinguished elements of the device. Accordingly, the elements of the above-described device may be mounted as one chip or multiple chips depending on the design of the device. In addition, some components of the terminal (100), such as the user interface (140) and the display unit (150), may be selectively provided in the terminal (100). In addition, the user interface (140) and the display unit (150), etc. may be additionally provided in the base station (200) as needed.

[0164] The terminal can receive a physical downlink control channel (PDCCH) transmitted from a base station. In order to receive the downlink control channel from the base station, the terminal can receive information such as a control resource set (CORESET) or a search space.

[0165] A control resource set may include information about a frequency domain in which a physical downlink control channel must be received. Specifically, a base station may provide information about a control resource set to a terminal. The information about the control resource set may include an index of a physical resource block (PRB) or PRB sets through which the terminal must receive a physical downlink control channel, and the number of consecutive symbols. The number of consecutive symbols may be one of 1, 2, or 3.

[0166] A search space may include time information for receiving a set of PRBs indicated by the control resource set. Specifically, a base station may provide information about the search space to a terminal, and at this time, the information about the search space may include at least one of periodicity and offset. Here, the period and offset may be set in units of slots, sub-slots, symbols, symbol sets, or slot sets. The information about the search space may include a CCE aggregation level (AL) received by the terminal, the number of PDCCHs monitored by the terminal for each CCE aggregation level, a search space type, a DCI format monitored by the terminal, and RNTI information.

[0167] The CCE aggregation level can have at least one of the values ​​1, 2, 4, 8, and 16. The terminal can monitor the PDCCH in the same number of CCEs as the value of the CCE aggregation level.

[0168] Search spaces can be categorized into two types. Specifically, search spaces can be categorized into a common search space (CSS) and a UE-specific search space. A common search space can be a search space where all UEs within a cell or some UEs within a cell commonly monitor the PDCCH. A terminal may monitor candidates for PDCCH (e.g., a PDCCH carrying a DCI having a CRC scrambled with at least one RNTI among SI-RNTI, RA-RNTI, MsgB-RNTI, P-RNTI, TC-RNTI, INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, TPC-SRS-RNTI, CI-RNTI, C-RNTI, MCS-C-RNTI, CS-RNTI(s), or PS-RNTI) broadcast to all terminals within a cell or some terminals within a cell in a common search space and receive the PDCCH. A terminal-specific search space may be a search space in which a specific terminal monitors the PDCCH. A specific terminal may monitor candidates for PDCCHs (e.g., PDCCHs carrying DCIs having a CRC scrambled with at least one RNTI among C-RNTI, MCS-C-RNTI, SP-CSI-RNTI, CS-RNTI(s), SL-RNTI, SL-CS-RNTI, or SL-L-CS-RNTI) transmitted to the specific terminal in a terminal-specific search space and receive the PDCCHs. In addition, the terminal may receive a PDCCH including a DCI indicating reception of a physical downlink shared channel, transmission of a physical uplink control channel, or transmission of a physical uplink shared channel in the common search space and the terminal-specific search space.

[0169] The DCI format monitored by a terminal receiving scheduling for transmission of a PUSCH and reception of a PDSCH from a base station may be DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, and 1_2. RNTI information may include at least one of a CS-RNTI, an MCS-C-RNTI, and a C-RNTI for DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, and 1_2. Here, the CS-RNTI may be used to activate / release a semi-persistent scheduling (SPS) PDSCH or a configured grant (CG) PUSCH. In addition, the CS-RNTI may be used to schedule retransmission of an SPS PDSCH or a CG PUSCH. Here, MCS-C-RNTI can be used to schedule PDSCH or PUSCH using MCS (modulation and coding scheme) with high reliability. C-RNTI can be used to schedule PDSCH or PUSCH.

[0170] The DCI format that can be included in the PDCCH monitored by the terminal may further include the following information.

[0171] DCI format 2_0 may include information about a dynamic slot format indicator (SFI) that indicates the direction of symbols constituting a slot. At this time, the direction of the symbol may be uplink, downlink, or flexible. At this time, a symbol having an uplink direction is used for uplink transmission, a symbol having a downlink direction is used for downlink reception, and a symbol having a flexible direction can be used for both uplink transmission and downlink reception. The RNTI used for DCI format 2_0 may be SFI-RNTI.

[0172] DCI format 2_1 may include a downlink preemption indication or an interrupted transmission indication, which indicates that there is no downlink transmission on the PRB(s) and symbol(s) performed by the base station to the terminal. The RNTI used for DCI format 2_1 may be an INT-RNTI.

[0173] DCI format 2_4 may include an uplink cancellation indication (UL cancellation indication) that indicates cancellation of uplink transmission on PRB(s) performed by the terminal to the base station. The RNTI used for DCI format 2_4 may be a CI-RNTI.

[0174] The terminal can determine PDCCH candidates that should receive the PDCCH through the set of control resources and information on the search space. The terminal can monitor the PDCCH candidates and check the CRC based on the RNTI value to determine whether the correct PDCCH has been received. The RNTI value can include at least the C-RNTI, MCS-C-RNTI, CS-RNTI, as well as the SFI-RNTI, INT-RNTI, and CI-RNTI values.

[0175] When a terminal receives a PDCCH, the terminal can decode information about a control resource set and a search space based on the DCI included in the PDCCH, and perform an operation indicated by the DCI. At this time, the format of the DCI included in the PDCCH received by the terminal may be one of the DCI formats 0_0, 0_1, and 0_2 for scheduling a PUSCH. In addition, the format of the DCI included in the PDCCH received by the terminal may be one of the DCI formats 1_0, 1_1, and 1_2 for scheduling a PDSCH. In addition, the format of the DCI included in the PDCCH received by the terminal may be one of the DCI formats 1_0, 1_1, and 1_2 for scheduling a PUCCH. In this case, the PUCCH may include HARQ-ACK information. Additionally, the format of the DCI included in the PDCCH received by the terminal may be one of DCI formats 2_0, 2_1, or 2_4.

[0176] When a terminal receives a DCI of DCI format 1_0, 1_1, or 1_2 for scheduling a PDSCH, the terminal can receive the PDSCH scheduled by the DCI. To this end, the terminal must determine the slot in which the PDSCH is scheduled and the start index and length (number of symbols) of the symbol within the slot based on the received DCI. The TDRA (time domain resource assignment) field of the DCI of DCI format 1_0, 1_1, or 1_2 received by the terminal can indicate a K0 value, which is timing information of the scheduled slot, and a SLIV (starting length indicator value) value, which is the index and length of the starting symbol within the slot. Here, the value of K0 can be a non-negative integer value. Here, SLIV can be a jointly encoded value of the index (S) and length (L) values ​​of the starting symbol within the slot. The index (S) and length (L) values ​​of the starting symbol within the slot can be values ​​transmitted separately. Here, S can have one of the values ​​0, 1, ..., 13 for a normal CP. At this time, L can have one of the natural numbers that satisfy the condition that S+L is less than or equal to 14. S can have one of the values ​​0, 1, ..., 11 for an extended CP. At this time, L can have one of the natural numbers that satisfy the condition that S+L is less than or equal to 12.

[0177] The terminal can determine the slot in which the PDSCH should be received based on the K0 value. Specifically, the slot in which the PDSCH should be received can be determined based on the K0 value, the index of the slot in which the DCI is received, the subcarrier spacing (SCS) of the downlink BWP in which the DCI is received, and the subcarrier spacing of the downlink BWP in which the scheduled PDSCH is received.

[0178] For example, there may be a case where the subcarrier spacing of the downlink BWP that receives the DCI and the downlink BWP that receives the scheduled PDSCH are the same, and the DCI is received in downlink slot n. In this case, the terminal can receive the PDSCH in downlink slot n+K0. In this specification, slot x may mean a slot having an index x or the xth slot.

[0179] For example, the subcarrier spacing of the downlink BWP that receives DCI may be 15kHz*2^mu_PDCCH, the subcarrier spacing of the downlink BWP that receives the scheduled PDSCH may be 15kHz*2^mu_PDSCH, and the UE may receive DCI in downlink slot n. The index of downlink slot n may be an index according to the subcarrier spacing of the downlink BWP that receives the DCI. In this case, the UE may receive the PDSCH in the slot floor(n*2^mu_PDSCH / 2^mu_PDCCH)+K0. At this time, floor(n*2^mu_PDSCH / 2^mu_PDCCH)+K0 may be an index determined according to the subcarrier spacing of the downlink BWP that transmits the PDSCH. mu_PDCCH and mu_PDSCH may have values ​​of 0, 1, 2, and 3.

[0180] Figure 12 illustrates scheduling of a physical downlink shared channel according to one embodiment of the present invention.

[0181] Referring to FIG. 12, a terminal can receive a PDCCH scheduling a PDSCH in downlink slot (DL slot) n. The DCI included in the PDCCH can indicate K0 as 3 (K0=3). At this time, if the subcarrier spacing of the DL BWP where the PDCCH is transmitted and the subcarrier spacing of the DL BWP where the PDSCH is scheduled are the same, the terminal can determine that the PDSCH is scheduled in downlink slot n+K0, i.e., slot n+3.

[0182] The terminal can determine the slot for receiving the PDSCH using the K0 value, and can determine the symbol in which the PDSCH is transmitted using the index (S) and length (L) values ​​of the start symbol within the slot for receiving the PDSCH. The symbol in which the PDSCH is transmitted can be from symbol S to symbol S+L-1 within the slot calculated based on the K0 value. From symbol S to symbol S+L-1 can be L consecutive symbols.

[0183] The terminal may be additionally configured for downlink slot aggregation from the base station. At this time, the downlink slot aggregation may have values ​​of 2, 4, or 8. When the terminal is configured for downlink slot aggregation, the terminal may receive PDSCH in consecutive slots according to the slot aggregation value, starting from the slot obtained based on the K0 value.

[0184] When a terminal receives DCI format 1_0, 1_1, 1_2, which is a DCI for scheduling a PUCCH, the terminal can transmit the PUCCH scheduled by the DCI to the base station. At this time, the PUCCH can include HARQ-ACK information. The 'PDSCH-to-HARQ_feedback timing indicator' field included in DCI formats 1_0, 1_1, 1_2 can indicate a K1 value, which is information about a slot in which the scheduled PUCCH can be transmitted. K1 can have a non-negative integer value. DCI format 1_0 can indicate one of {0, 1, 2, 3, 4, 5, 6, 7} as the K1 value. The K1 values ​​that can be indicated in DCI formats 1_1, 1_2 can be configured or set from a higher layer. The HARQ-ACK information may be HARQ-ACK information indicating whether reception of two types of channels is successful. As a first type, when a terminal receives a PDSCH schedule through DCI of DCI format 1_0, 1_1, or 1_2, it may be HARQ-ACK information indicating whether the terminal has successfully received the PDSCH. As a second type, when the DCI of DCI format 1_0, 1_1, or 1_2 received by the terminal indicates the release of the SPS PDSCH, it may be HARQ-ACK information indicating whether the terminal has received the DCI indicating the release of the SPS PDSCH.

[0185] The terminal may determine the uplink slot in which the PUCCH including the first type of HARQ-ACK information is transmitted as follows. The terminal may determine the slot in which the PUCCH is transmitted based on the uplink slot that overlaps with the last symbol in which the PDSCH corresponding to the HARQ-ACK information is transmitted. For example, if the index of the uplink slot is m, the index of the uplink slot in which the PUCCH including the HARQ-ACK information is transmitted may be m+K1. The index of the uplink slot may be a value determined based on the subcarrier spacing of the BWP in which the PUCCH is transmitted. When the terminal is configured for downlink slot aggregation, the last symbol in which the PDSCH is transmitted may be the last symbol in which the PDSCH is scheduled within the last slot among the slots in which the PDSCH is received.

[0186] Figure 13 illustrates scheduling of a physical uplink control channel according to one embodiment of the present invention.

[0187] Referring to FIG. 13, a terminal may receive a PDCCH scheduling a PDSCH in downlink slot n. At this time, the DCI included in the PDCCH may indicate a K0 value as 3 and a K1 value as 2. In addition, the subcarrier spacing of the DL BWP in which the PDCCH is received, the subcarrier spacing of the DL BWP in which the PDSCH is scheduled, and the subcarrier spacing of the UL BWP in which the PUCCH is transmitted may be the same. In this case, the terminal may receive a PDSCH in downlink slot n+K0, i.e., downlink slot n+3. The terminal may determine an uplink slot that overlaps with the last symbol of the PDSCH scheduled in downlink slot n+3. At this time, the last symbol of the PDSCH scheduled in downlink slot n+3 overlaps with the uplink slot n+3. Accordingly, the terminal can transmit a PUCCH including the first type of HARQ-ACK information on uplink slot n+3+K1, i.e., slot n+5.

[0188] In addition, the terminal can determine the slot in which the PUCCH including the second type of HARQ-ACK information is transmitted as follows. The terminal can determine the uplink slot overlapping the last symbol in which the PDCCH corresponding to the second type of HARQ-ACK information is transmitted as the slot in which the second type of HARQ-ACK information is transmitted. When the index of the uplink slot is m, the terminal can transmit the PUCCH including the second type of HARQ-ACK information on the uplink slot m+K1. In this case, the index of the uplink slot can be determined according to the subcarrier spacing of the uplink BWP in which the PUCCH is transmitted.

[0189] FIG. 14 illustrates scheduling of a physical uplink shared channel and a physical uplink control channel according to one embodiment of the present invention.

[0190] Referring to FIG. 14, a terminal may receive a DCI indicating release of an SPS PDSCH in a downlink slot n. At this time, the DCI may indicate a K1 value as 3. The subcarrier spacing of the DL BWP in which the PDCCH is received and the subcarrier spacing of the UL BWP in which the PUCCH is transmitted may be the same. In this case, the terminal may determine an uplink slot that overlaps with the last symbol of the PDCCH received in slot n. The terminal may determine that a PUCCH including HARQ-ACK information of the DCI indicating release of an SPS PDSCH is scheduled in an uplink slot n+K1, i.e., n+3.

[0191] When a terminal receives DCI format 0_0, 0_1, 0_2, which is DCI for scheduling a PUSCH, the terminal can transmit the scheduled PUSCH to the base station. To do this, the terminal must determine the slot in which the PUSCH is scheduled and the starting index and length (number of symbols) of the symbol within the slot from the DCI. The TDRA (time domain resource assignment) field of the DCI format 0_0, 0_1, 0_2 can indicate a K2 value, which is information about the slot in which the PUSCH is scheduled, and a SLIV (starting length indicator value), which is a value for information about the index and length of the starting symbol within the slot. Here, K2 can have a non-negative integer value. Here, SLIV can be a value obtained by jointly encoding the index (S) and length (L) of the starting symbol within the slot. In addition, SLIV can separately indicate the index (S) and length (L) of the starting symbol within the slot. Here, S can have one of the values ​​0, 1, ..., 13 for normal CP, and L can have one of the natural numbers satisfying the condition that S+L is less than or equal to 14. S can have one of the values ​​0, 1, ..., 11 for extended CP, and L can have one of the natural numbers satisfying the condition that S+L is less than or equal to 12.

[0192] The terminal can determine the slot in which the PUSCH is transmitted based on the K2 value. Specifically, the terminal can determine the slot in which the PUSCH is transmitted based on the K2 value, the index of the slot in which the DCI is transmitted, the subcarrier spacing of the downlink BWP in which the DCI is transmitted, and the subcarrier spacing of the uplink BWP in which the PUSCH is transmitted.

[0193] For example, if the subcarrier spacing of the downlink BWP through which DCI is transmitted and the uplink BWP through which the scheduled PUSCH is transmitted are the same, and the terminal receives the DCI in downlink slot n, the terminal can transmit the PUSCH in uplink slot n+K2.

[0194] For example, if the subcarrier spacing of the downlink BWP through which DCI is transmitted is 15kHz*2^mu_PDCCH, and the subcarrier spacing of the uplink BWP through which the scheduled PUSCH is transmitted is 15kHz*2^mu_PUSCH, the UE can receive DCI in the downlink slot n. Here, the index of the downlink slot n can be determined according to the subcarrier spacing of the downlink BWP through which DCI is transmitted. At this time, the UE can transmit the PUSCH in the slot floor(n*2^mu_PUSCH / 2^mu_PDCCH)+K2. The index of the uplink slot floor(n*2^mu_PUSCH / 2^mu_PDCCH)+K2 can be determined according to the subcarrier spacing of the uplink BWP through which the PUSCH is transmitted. mu_PDCCH and mu_PUSCH can have the values ​​of 0, 1, 2, and 3.

[0195] Referring to FIG. 14, a terminal may receive a PDCCH scheduling a PUSCH in downlink slot n. The DCI included in the PDCCH may indicate a K2 value of 3. The subcarrier spacing of the DL BWP where the PDCCH is transmitted and the subcarrier spacing of the UL BWP where the PUSCH is transmitted may be the same. At this time, the terminal may determine that the PUSCH is scheduled in uplink slot n+K2, i.e., slot n+3.

[0196] The terminal determines a slot for transmitting a PUSCH based on the K2 value, and determines a symbol capable of transmitting the PUSCH using the index (S) and length (L) values ​​of the start symbol within the determined slot. Specifically, the symbol for transmitting the PUSCH may be from symbol S to symbol S+L-1 within the slot determined based on the K2 value. Symbol S to symbol S+L-1 may be L consecutive symbols.

[0197] Additionally, the terminal may be configured for uplink slot aggregation from the base station. The uplink slot aggregation value may be 2, 4, or 8. When the terminal is configured for uplink slot aggregation, the terminal may transmit a PUSCH on consecutive slots corresponding to the slot aggregation value from a slot determined based on the K2 value.

[0198] In FIGS. 12 to 14, the terminal may use the values ​​of K0, K1, and K2 to determine the slot in which the scheduled PDSCH is transmitted, the slot in which the PUCCH is transmitted, and the slot in which the PUSCH is transmitted. In this specification, the slot determined when the values ​​of K0, K1, and K2 are 0 may be described as a reference point or reference slot. That is, in FIG. 12, the reference slot may be a downlink slot n, which is a slot in which the PDCCH is received, in FIG. 13, the reference slot may be an uplink slot n+3, which is an uplink slot overlapping the last symbol in which the PDSCH is transmitted, and in FIG. 14, the reference slot may be an uplink slot n, which is an uplink slot overlapping the last symbol in which the PDCCH is transmitted.

[0199] In this specification, uplink slots and downlink slots may be referred to as slots without distinction. In the following, it is assumed that the subcarrier spacing of the downlink BWP, where the PDSCH and PDCCH are transmitted, and the subcarrier spacing of the uplink BWP, where the PUSCH and PUCCH are transmitted, are identical.

[0200] To increase PDCCH reception reliability, a terminal may be configured to receive repeated PDCCH reception from a base station. The PDCCH reception reliability may be based on the CCE aggregation level (AL) for the PDCCH. For example, a terminal may have higher reliability when receiving a PDCCH at CCE aggregation level 8 or 16 than when receiving it at CCE aggregation level 1 or 2. In this specification, reception reliability may refer to the probability that a terminal successfully receives a PDCCH.

[0201] The base station can configure the CCE aggregation level and the number of PDCCH candidates monitored by the terminal per CCE aggregation level through the control resource set and search space information for the terminal to receive the PDCCH. In certain situations, the terminal, for example, located at the cell edge, may require a high CCE aggregation level for PDCCH reception. However, there may be cases where the control resource set configured by the base station for the terminal cannot provide the CCE aggregation level for PDCCH reception. For example, to support CCE aggregation level 16 for PDCCH reception, the control resource set of the terminal requires 16 CCEs, i.e., 96 resource element groups (REGs). In this case, if the control resource set is 2 symbols, the control resource set must be allocated at least 48 RB(s) on the resources of the frequency domain to include 96 REGs. However, if the bandwidth of the frequency range supported by the terminal is narrow, or if the base station configures the terminal to use only a narrow bandwidth for channel reception, the control resource set may not support CCE aggregation level 16. In situations where it is difficult to configure a high CCE aggregation level, the base station can configure the terminal to repeatedly receive the PDCCH.

[0202] In this specification, PDCCH 1A, PDCCH 1B, etc. may refer to PDCCHs that the terminal receives by monitoring PDCCH #1A candidates, PDCCH #1B candidates, etc. In addition, in this specification, (repeated) PDCCH candidates and (repeated) PDCCHs may be described interchangeably.

[0203] Below, a specific method for setting a base station to repeatedly receive a PDCCH from a terminal is described through FIGS. 15 to 17.

[0204] FIG. 15 illustrates that PDCCH is repeatedly transmitted in different control resource sets according to one embodiment of the present invention.

[0205] Referring to FIG. 15, the terminal may assume that PDCCHs transmitted on different sets of control resources include the same DCI. Specifically, the terminal may monitor in CORESET A of the first slot (slot n of FIG. 15) to receive PDCCH 1A, and the terminal may monitor in CORESET B of the second slot (slot n+1 of FIG. 15) to receive PDCCH 1B. At this time, the terminal may be preset by the base station that PDCCH 1A and PDCCH 1B are PDCCHs including the same DCI. The terminal may independently decode PDCCH 1A and PDCCH 1B to obtain DCI information. However, if DCI information is not obtained even after independently decoding PDCCH 1A and PDCCH 1B, the DCI information may be obtained by combining and decoding PDCCH 1A and PDCCH 1B. In addition to the above-described PDCCH 1A and PDCCH 1B, PDCCH 1C can be received on CORESET C, and PDCCH 1D can be received on CORESET D. In addition, although FIG. 15 describes that the same DCI is included in the PDCCHs of CORESETs of different slots (e.g., slot n and slot n+1), multiple CORESETs can be configured within one slot, the terminal can receive PDCCHs on each of the multiple CORESETs, and the PDCCHs received respectively can include the same DCI. In other words, the first slot and the second slot can be different slots or the same slot. In addition, at this time, PDCCHs including the same DCI can have the same CCE aggregation level.

[0206] FIG. 16 illustrates that PDCCH is repeatedly transmitted in different search spaces according to one embodiment of the present invention.

[0207] Referring to FIG. 16, the base station can set multiple search spaces for a single CORESET (CORESET A in FIG. 16) to the terminal. That is, the CORESET is set to the same resource region for each slot, but the search spaces of each slot can be set to different time resource regions. The terminal can assume that the PDCCHs transmitted on the multiple search spaces include the same DCI. Since one CORESET is the same resource region for each slot, the frequency domain and time domain length (number of symbols) in which the PDCCHs are transmitted are the same. The terminal can monitor in search space A of CORESET A of the first slot (slot n in FIG. 16) to receive PDCCH 1A, and the terminal can monitor in search space B of CORESET A of the second slot (slot n+1 in FIG. 16) to receive PDCCH 1B. The base station can preset for the terminal that the DCIs included in PDCCH 1A and PDCCH 1B are the same. The terminal can obtain DCI information by independently decoding PDCCH 1A and PDCCH 1B. However, if DCI information is not obtained even after independently decoding PDCCH 1A and PDCCH 1B, DCI information can be obtained by combining and decoding PDCCH 1A and PDCCH 1B. In addition, the terminal can receive PDCCH 1C in search space C and PDCCH 1D in search space D in addition to PDCCH 1A and PDCCH 1B. In addition, although FIG. 16 describes that the same DCI is included in PDCCHs transmitted on search spaces of different slots (e.g., slot n and slot n+1), multiple search spaces may be set within one slot, the terminal can receive PDCCHs on each of the multiple search spaces, and the PDCCHs received on each of the multiple search spaces may include the same DCI. In other words, the first slot and the second slot may be different slots or the same slot.Additionally, PDCCHs containing the same DCI at this time may have the same CCE aggregation level.

[0208] For convenience of explanation, in this specification, PDCCHs containing identical DCI information may be referred to as repetitive PDCCHs. Furthermore, a PDCCH transmitted only once may also be included in a repetitive PDCCH. For example, in FIGS. 15 and 16 , the PDCCHs may be configured as PDCCH 1A, PDCCH 1B, PDCCH 1C, and PDCCH 1A, which are repeated four times.

[0209] When a terminal is configured to receive a repetitive PDCCH from a base station, the terminal can monitor PDCCH candidates configured to be repeatedly received including the same DCI information (e.g., PDCCH #1A candidate, PDCCH #1B candidate, PDCCH #1C candidate, and PDCCH #1D candidate of FIGS. 15 and 16) to receive the PDCCH and determine whether the DCI included in the received PDCCH has been correctly received. The terminal can determine whether one, multiple, or all of the repetitive PDCCHs have been successfully received. For example, when the PDCCH is configured to be repeatedly transmitted four times, the terminal can successfully receive the DCI included in the corresponding PDCCH by monitoring only the PDCCH #1A candidate. In addition, the terminal can successfully receive the DCI included in the corresponding PDCCH by monitoring the PDCCH #1B candidate and the PDCCH #1C candidate. Additionally, the terminal can monitor the PDCCH#1A candidate, the PDCCH#1B candidate, the PDCCH#1C candidate, and the PDCCH#1D candidate to successfully receive the DCI included in the corresponding PDCCH.

[0210] FIG. 17 illustrates that different repetitive PDCCHs overlap in the time-frequency domain according to one embodiment of the present invention.

[0211] The base station may be configured to receive the first repetition PDCCH by monitoring the first repetition PDCCH candidate in the first CORESET and search space. Similarly, the base station may be configured to receive the second repetition PDCCH, the third repetition PDCCH candidate, and the fourth repetition PDCCH candidate in the second CORESET and search space, the third CORESET and search space, and the fourth CORESET and search space, respectively, by monitoring the second repetition PDCCH candidate, the third repetition PDCCH candidate, and the fourth repetition PDCCH.

[0212] Referring to FIG. 17, the terminal can receive the first repetition PDCCH by monitoring the repeated PDCCH#1 candidate (the first repeated PDCCH candidate) on the first CORESET and search space. The first repeated PDCCH can be configured to be transmitted repeatedly four times. The four repeated PDCCHs can be PDCCHs transmitted on the PDCCH#1A candidate of slot n, the PDCCH#1B candidate of slot n+1, the PDCCH#1C candidate of slot n+2, and the PDCCH#1D of slot n+3. The terminal can receive the second repetition PDCCH by monitoring the repeated PDCCH#2 candidate (the second repeated PDCCH candidate) on the second CORESET and search space. The second repeated PDCCH can be configured to be transmitted repeatedly twice. The PDCCH that is repeated twice may be a PDCCH transmitted on a PDCCH#2A candidate of slot n+1 and a PDCCH#2B candidate of slot n+2. The terminal may monitor the repeated PDCCH#3 candidate (the third repeated PDCCH candidate) on the third CORESET and search space to receive the third repeated PDCCH. The third repeated PDCCH may be configured to be received without repetition in slot n+2. At this time, the received PDCCH may include a DCI in a DCI format having a CRC scrambled with C-RNTI, MCS-C-RNTI, CS-RNTI, SFI-RNTI, INT-RNTI, or CI-RNTI. At this time, the format of the DCI that is received may include DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, 1_2, 2_0, 2_1, to 2_4.

[0213] Referring to FIG. 17, there may be cases where the resources for monitoring PDCCHs transmitted on different CORESETs and search spaces set by the terminal from the base station overlap. Specifically, the base station may configure the terminal to repeatedly monitor the repetitive PDCCH#1 candidate (the first repetitive PDCCH candidate) in slots n, n+1, n+2, and n+3. The base station may configure the terminal to repeatedly monitor the repetitive PDCCH#2 candidate (the second repetitive PDCCH candidate) in slots n+1 and n+2. That is, the terminal must monitor the repetitive PDCCH#1 candidate and the repetitive PDCCH#2 candidate in slots n+1 and n+2, and receive the corresponding PDCCH. At this time, if the time-frequency resource regions of slots n+1 and n+2, where PDCCH#1 is transmitted, overlap with the resources where PDCCH#2 is transmitted, the terminal performs monitoring and cannot distinguish whether the PDCCH received on slots n+1 and n+2 is a repetitive PDCCH#1 or a repetitive PDCCH#2. Therefore, even if the terminal successfully receives the repetitive PDCCH, when decoding the DCI information included in the received repetitive PDCCH, a problem may arise as to whether the received PDCCH should be determined as a repetitive PDCCH#1 or a repetitive PDCCH#2. In addition, the base station may configure the terminal to monitor the repetitive PDCCH#3 candidate (the third repetitive PDCCH candidate) in slot n+2 without repetition and receive the corresponding PDCCH. At this time, the terminal can monitor the repetitive PDCCH#1 candidate, the repetitive PDCCH#2 candidate, and the PDCCH#3 candidate in slot n+2 and receive the corresponding PDCCH. If the time-frequency resource regions of slot n+2 in which PDCCH #1, PDCCH #2, and PDCCH #3 are transmitted overlap, the terminal cannot distinguish whether the PDCCH received in slot n+2 is a repeated PDCCH #1, a repeated PDCCH #2, or PDCCH #3.Therefore, even if the terminal successfully receives the repetitive PDCCH, when decoding the DCI information included in the received repetitive PDCCH, a problem may arise as to whether the received PDCCH should be determined as repetitive PDCCH#1, repetitive PDCCH#2, or repetitive PDCCH#3. The overlapping of the above-described time-frequency resource regions may include a case where the resource regions in which the PDCCHs are transmitted overlap completely. In other words, it may include a case where the CCEs in which each PDCCH is transmitted overlap completely.

[0214] Below, we describe PDCCH ambiguity, i.e., a case where a terminal cannot determine which repetitive PDCCH is being transmitted due to the overlapping of the above-described time-frequency resource domains.

[0215] FIG. 18 illustrates a problem that occurs when determining a slot in which a physical downlink shared channel is scheduled, according to one embodiment of the present invention.

[0216] FIG. 18 is a diagram illustrating a problem with the K0 value described above. Referring to FIG. 18(a), if the DCI successfully received by the terminal is included in the first repetition PDCCH (configured to be repeatedly transmitted 4 times), the terminal may regard slot n+3, in which the last repetition PDCCH of the first repetition PDCCH is transmitted, as a reference slot, and apply the K0 value from the reference slot. That is, the terminal may determine that the PDSCH is scheduled to be transmitted in slot n+3+K0 (n+3+3), i.e., slot n+6. Referring to FIG. 18(b), if the DCI successfully received by the terminal is included in the second repetition PDCCH (configured to be repeatedly transmitted 2 times), the terminal may regard slot n+2, in which the last repetition PDCCH of the second PDCCH is transmitted, as a reference slot, and apply the K0 value from the reference slot. That is, the terminal can determine that the PDSCH is scheduled to be transmitted in slot n+5, which is slot n+2+K0(n+2+3). Therefore, different results may occur depending on which repetitive PDCCH the terminal considers the DCI it successfully received to be included in.

[0217] FIG. 19 illustrates a problem that occurs when determining a slot in which a physical uplink shared channel and a physical uplink control channel are scheduled according to one embodiment of the present invention.

[0218] Figure 19 is a diagram showing the problem with the K1 and K2 values ​​described above.

[0219] First, the issue regarding the K1 value will be explained with reference to FIG. 19. The PUCCH of FIG. 19 may include HARQ-ACK information for the DCI indicating the release of the SPS PDSCH. Referring to FIG. 19(a), if the DCI successfully received by the terminal is included in the first repetition PDCCH (configured to be transmitted four times), the terminal may consider slot n+3, in which the last repetition PDCCH of the first repetition PDCCH is transmitted, as a reference slot and apply the K1 value from the reference slot. That is, the terminal may determine that the PUCCH is scheduled to be transmitted in slot n+5, which is slot n+3 + K1 (n+3+2). Referring to Fig. 19(b), if the DCI successfully received by the terminal is included in the second repetition PDCCH (configured to be transmitted repeatedly twice), the terminal may consider slot n+2, in which the last repetition PDCCH of the second repetition PDCCH is transmitted, as a reference slot and apply the K1 value from the reference slot. That is, the terminal may determine that the PUCCH is scheduled to be transmitted in slot n+4, which is slot n+2+K2(n+2+2). Therefore, different results may occur depending on which repetition PDCCH the terminal considers the DCI successfully received to be included in.

[0220] Next, the problem with respect to the K2 value will be described with reference to FIG. 19. Referring to FIG. 19(a), if the DCI successfully received by the terminal is included in the first repetition PDCCH (configured to be repeatedly transmitted four times), the terminal may regard slot n+3, in which the last repetition PDCCH of the first PDCCH is transmitted, as a reference slot, and apply the K2 value from the reference slot. That is, the terminal may determine that the PUSCH is scheduled to be transmitted in slot n+3+K2 (n+3+2), i.e., slot n+5. Referring to FIG. 19(b), if the DCI successfully received by the terminal is included in the second repetition PDCCH (configured to be repeatedly transmitted twice), the terminal may regard slot n+2, in which the last repetition PDCCH of the second repetition PDCCH is transmitted, as a reference slot, and apply the K2 value from the reference slot. That is, the terminal can determine that the PUSCH is scheduled to be transmitted in slot n+4, which is slot n+2+K2(n+2+2). Therefore, different results may occur depending on which repetitive PDCCH the terminal considers the DCI it successfully received to be included in.

[0221] FIG. 20 illustrates that slots are determined according to a dynamic slot format indicator according to one embodiment of the present invention.

[0222] Figure 20 is a diagram showing a problem that occurs when applying a slot indicated by a dynamic slot format indicator (SFI) and the symbol configuration (uplink, downlink, flexible) of the indicated slot.

[0223] The DCI of DCI format 2_0 included in the first repetition PDCCH transmitted by the base station may include Dynamic SFI. The terminal may determine the slot and the symbol configuration of the slot based on the Dynamic SFI. At this time, the slot indicated by the Dynamic SFI may be a specific number of slots from the last slot among the slots in which the repetition PDCCH is transmitted. At this time, the specific number may be set by RRC. For example, referring to FIG. 20, the base station may set the terminal to repeatedly receive the first repetition PDCCH in slot n, slot n+1, slot n+2, and slot n+3. The terminal may apply the symbol configuration indicated by the Dynamic SFI to four slots from slot n+3, which is the last slot in which the first repetition PDCCH is transmitted. In Fig. 20, it is described that the slot configuration indicated by Dynamic SFI is applied from the last slot in which the first repetition PDCCH is transmitted, but the slot configuration indicated by Dynamic SFI may be applied from the first slot in which the first repetition PDCCH is transmitted, or from a slot after the number of slots set from a higher layer after the first slot, or from a slot after the number of slots set from a higher layer after the last slot.

[0224] Figure 21 illustrates a problem that occurs when a slot is determined according to a dynamic slot format indicator according to one embodiment of the present invention.

[0225] FIG. 21 is a diagram illustrating a slot indicated by Dynamic SFI and a problem that occurs when the symbol configuration of the indicated slot is applied. Referring to FIG. 21(a), if the DCI in DCI format 2_0 that the terminal successfully receives is included in the first repetition PDCCH (configured to be repeatedly transmitted 4 times), the terminal can apply the symbol configuration indicated by Dynamic SFI from slot n+3, which is the last slot among the slots in which the first repetition PDCCH is transmitted. Referring to FIG. 21(b), if the DCI in DCI format 2_0 that the terminal successfully receives is included in the second repetition PDCCH (configured to be repeatedly transmitted 2 times), the terminal can apply the symbol configuration indicated by Dynamic SFI from slot n+2, which is the last slot among the slots in which the second repetition PDCCH is transmitted. Therefore, the slot to which the symbol configuration indicated by Dynamic SFI is applied may vary depending on which repetition PDCCH the terminal considers the DCI that the terminal successfully receives to be included in.

[0226] FIG. 22 illustrates that a slot is determined based on a downlink preemption indicator according to one embodiment of the present invention.

[0227] Figure 22 is a diagram illustrating a problem related to resources in the time-frequency domain indicated by a downlink preemption indication.

[0228] The base station may transmit to the terminal a DCI in DCI format 2_1 including a downlink preemption indicator in the first repetition PDCCH. The terminal may determine a reference downlink resource to determine a resource in the time-frequency domain indicated by the downlink preemption indicator. The downlink preemption indicator may indicate some of the time-frequency domain resources among the reference downlink resources.

[0229] Hereinafter, a method for a terminal to determine a reference downlink resource will be described with reference to FIG. 22. At this time, the transmission period of the first repetitive PDCCH including a downlink preemption indicator may be 8 slots. In addition, for convenience of explanation, the first repetitive transmission (transmission of the repetitive PDCCH on slots n to n+3 of FIG. 22) is described as transmission in the first period, and the second repetitive transmission (transmission of the repetitive PDCCH on slots n+8 to n+11 of FIG. 22) is described as transmission in the second period. That is, the first period may be slots n to n+3, and the second period may be slots n+8 to n+11.

[0230] Referring to FIG. 22(a), when a terminal receives a first repetition PDCCH including a downlink preemption indicator transmitted during a second period, the reference downlink resource of the downlink preemption indicator may include from immediately before the first symbol of the first repetition PDCCH among the first repetition PDCCHs in the second period (i.e., slot n+7 immediately before the first symbol of slot n+8 in FIG. 22(a)) to the first symbol of the first repetition PDCCH among the first repetition PDCCHs in the first period (the first symbol of slot n in FIG. 22(a)) (slot n to slot n+7 in FIG. 22(a)). In other words, the reference downlink resource of the downlink preemption indicator may include P slots or P*N immediately before the first symbol of the first repetition PDCCH among the first repetition PDCCHs in the second period. slot symb It can contain symbols of . P is the transmission period of the first repetitive PDCCH and P can be 8. N slot symb refers to the number of symbols that constitute a slot. According to Fig. 22(a), the reference downlink resource is a resource located a certain time interval away from the last slot in which the first repeated PDCCH is transmitted. Therefore, a problem may arise in which the transmission of a rapid downlink preemption indicator is impossible.

[0231] Referring to FIG. 22(b), when the terminal receives the first repetitive PDCCH including the downlink preemption indicator transmitted during the second period, the reference downlink resource of the downlink preemption indicator may include from immediately before the first symbol of the last repetitive PDCCH among the first repetitive PDCCHs in the second period (i.e., slot n+10 immediately before the first symbol of slot n+11 in FIG. 22(b)) to the first symbol of the last repetitive PDCCH among the first repetitive PDCCHs in the first period (the first symbol of slot n+3 in FIG. 22(b)) (slot n+3 to slot n+10 in FIG. 22(b)). In other words, the reference downlink resource of the downlink preemption indicator may include P slots or P*N immediately before the first symbol of the last repetitive PDCCH among the first repetitive PDCCHs in the second period. slot symb It can contain symbols of . P is the transmission period of the first repetitive PDCCH and P can be 8. N slot symb refers to the number of symbols constituting a slot. Referring to FIGS. 22(a) and 22(b), the reference downlink resource includes slots or symbols in which the terminal receives a repetitive PDCCH (i.e., slot n to slot n+3 in FIG. 22(a), slot n+3 and slot n+8 to slot n+10 in FIG. 22(b)). If the terminal cannot simultaneously receive a PDCCH and a PDSCH in one symbol, the slots or symbols in which the repetitive PDCCH is transmitted may not be included in the reference downlink resource.

[0232] Referring to FIG. 22(c), when the terminal receives the first repetitive PDCCH including the downlink preemption indicator transmitted during the second period, the reference downlink resource of the downlink preemption indicator is Q slots or Q*N immediately before the first symbol of the first repetitive PDCCH among the first repetitive PDCCHs of the second period. slot symbIt can include 1 or Q symbols. Q can be the difference between the transmission period of the repetitive PDCCH including the downlink preemption indicator and the number of slots repeatedly transmitted, or a value set by the base station from the upper layer. Referring to Fig. 22(c), the transmission period of the repetitive PDCCH is 8 slots, and the number of slots repeatedly transmitted is 4, so Q can be 4 (8-4). N slot symb refers to the number of symbols included in a slot. According to Fig. 22(c), cases in which a slot or symbol for which repeated PDCCH transmission is set is included in the reference downlink resource, as in Figs. 22(a) and (b), may be excluded.

[0233] Figure 23 illustrates a problem that occurs when a slot is determined according to a downlink preemption indicator according to one embodiment of the present invention.

[0234] Hereinafter, with reference to FIG. 23, we describe the issues that arise when a terminal determines resources in the time-frequency domain indicated by the downlink preemption indicator. For convenience of explanation, we assume that the reference downlink resources are determined as described in FIG. 22(a).

[0235] Referring to Fig. 23(a), a first repetition PDCCH including DCI in DCI format 2_1 transmitted from a base station to a terminal may be configured to be repeatedly transmitted four times. At this time, as described in Fig. 22(a), the reference downlink resource may include symbols from slot n to slot n+7. In Fig. 23(b), a second repetition PDCCH including DCI in DCI format 2_1 transmitted from a base station to a terminal may be configured to be repeatedly transmitted twice. At this time, the terminal may determine the reference downlink resource based on slot n+9 in which the second repetition reception of the second repetition PDCCH is configured. The number of slots or symbols included in the reference downlink resource may be determined based on the transmission period of the second repetition PDCCH. That is, the reference downlink resource may include symbols from slot n+1 to slot n+8 (see Fig. 22(a)). Therefore, a problem may arise in which the reference downlink resource is determined differently depending on which repetitive PDCCH the terminal considers the DCI successfully received to be included in.

[0236] Figure 24 shows a slot determined according to an uplink cancellation indicator according to one embodiment of the present invention.

[0237] Referring to FIG. 24, the first repetitive PDCCH transmitted by the base station to the terminal may include a DCI in DCI format 2_4, which includes an uplink cancellation indication. The terminal may determine a reference UL resource to determine a resource in the time-frequency domain indicated by the UL cancellation indication. The UL cancellation indication may indicate some of the time-frequency domain resources among the reference UL resources.

[0238] Referring to FIG. 24, the reference uplink resource may be determined based on the last symbol (slot n+3 of FIG. 24) of the last PDCCH during the first repetition transmission of the first repetition PDCCH including the uplink cancellation indicator. Specifically, the reference uplink resource may include Y symbols after Tproc + X symbols after the last symbol. Here, Tproc is a value determined based on a processing time, and X may be a value set from a higher layer. Y may be a value set from a higher layer or determined based on a transmission period of the first repetition PDCCH. Referring to FIG. 24, Tproc=2, X=1, Y=4, and in this case, the unit of the values ​​of Tproc, X, and Y may be a symbol unit.

[0239] Figure 25 illustrates a problem that occurs when determining a slot based on an uplink cancellation indicator.

[0240] Figure 25 illustrates a problem that occurs when a terminal interprets resources in the time-frequency domain indicated by an uplink cancellation indicator.

[0241] Referring to Fig. 25(a), a reference uplink resource can be determined (slot n+7 to slot n+10) as described with reference to Fig. 24. That is, the last symbol of the last PDCCH for which the first repetition transmission of the first repetition PDCCH is configured is the symbol of slot n+3. Accordingly, from the last symbol of slot n+3 to the Y symbol after the Tproc+X symbol can be determined as the reference uplink resource. Referring to Fig. 25(b), the second repetition PDCCH transmitted by the base station to the terminal can include a DCI of DCI format 2_4 including an UL cancellation indication. In this case, the second repetition PDCCH can be configured to be repeated twice. The terminal can determine the reference uplink resource based on the last symbol of the last repetition PDCCH in the first repetition interval region in which the second repetition PDCCH is configured to be transmitted. That is, the last symbol of the last repetition PDCCH in the first repetition interval region of the second repetition PDCCH is the symbol of slot n+2. Therefore, the terminal can determine Y symbols after Tproc+X symbols from the last symbol of slot n+2 as the reference uplink resource. Therefore, a problem may arise in which the reference uplink resource is determined differently depending on which repetitive PDCCH the terminal considers the DCI successfully received to be included in.

[0242] Hereinafter, a method for resolving the above-described PDCCH ambiguity is described. That is, a method for determining which of multiple different repetitive PDCCHs the DCI received by the terminal is considered to be included in is described. In addition, the terminal can determine which repetitive PDCCH the received DCI is included in and transmit a HARQ-ACK for this to the base station. That is, the terminal can transmit a HARQ-ACK for a PDCCH determined according to the method described below to the base station. In this case, the HARQ-ACK transmitted by the terminal to the base station may be the first type HARQ-ACK and / or the second type HARQ-ACK described above.

[0243] i) Method 1

[0244] To distinguish between different repetitive PDCCHs, the base station may transmit additional information to the DCI to distinguish between the different repetitive PDCCHs. Upon successful reception of a repetitive PDCCH, the terminal can determine which repetitive PDCCH was successfully received based on the additional information included in the DCI. The information for distinguishing between different repetitive PDCCHs may include at least one of the following:

[0245] The DCI may include information on the number of times a repeated PDCCH is repeatedly transmitted as first information. That is, the DCI may include a value for the number of times a repeated PDCCH is repeatedly transmitted.

[0246] For example, if the number of repeated transmissions of a repetitive PDCCH transmitted by a base station to a terminal is 4, the DCI may include information (value) indicating the number of repeated transmissions (4) or information (value) that can infer the number of repeated transmissions.

[0247] As another example, if the first repetitive PDCCH received by the terminal is configured to be repeatedly transmitted four times and the second repetitive PDCCH is configured to be repeatedly transmitted twice, there may be a case where the first repetitive PDCCH and the second repetitive PDCCH completely overlap in the time-frequency domain resources of a single slot. In this case, the DCI may include an indicator for distinguishing the first repetitive PDCCH and the second repetitive PDCCH. If the number of types of repetitive PDCCHs is L, the DCI may indicate the types of repetitive PDCCHs using ceil(log2(L)) bits. ceil(x) is a function representing the smallest integer not less than x. Specifically, if the repetitive PDCCHs are of two types, the first repetitive PDCCH and the second repetitive PDCCH, the information for distinguishing the repetitive PDCCHs included in the DCI may be an indicator of the size of ceil(log2(2)) bits (i.e., 1 bit). If the value of the 1-bit indicator is '0', it can indicate a second repetition PDCCH that is repeatedly transmitted twice, and if it is '1', it can indicate a first repetition PDCCH that is repeatedly transmitted four times. In general, the terminal can obtain the number of repeated PDCCHs whose resources completely overlap in the time-frequency domain in any one slot. If the number of overlapping repeated PDCCHs is X, the required information can be represented by the size of ceil(log2(X)) bits. Each code point of the ceil(log2(X)) bits can indicate the number of repeated transmissions of the overlapping repeated PDCCHs. For example, the lowest value of the code point can indicate the number of repeated transmissions of the PDCCH with the lowest number of repeated transmissions among the repeated PDCCHs set to the terminal. At this time, the values ​​of the code points can indicate the number of repeated transmissions of the repeated PDCCHs in ascending order.

[0248] The second information included in the DCI may be information (value) indicating the ID of the CORESET corresponding to the repetitive PDCCH. For example, when the first repetitive PDCCH is transmitted on the first CORESET and the second repetitive PDCCH is transmitted on the second CORESET, there may be a case where the first repetitive PDCCH and the second repetitive PDCCH completely overlap in the time-frequency resource region of one slot. In this case, the DCI may include an indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. Specifically, when the repetitive PDCCH is of two types, the first repetitive PDCCH and the second repetitive PDCCH, the DCI may include a 1-bit indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. If the value of the 1-bit indicator is '0', it may indicate the first repetitive PDCCH transmitted on the first CORESET, and if the value of the indicator is '1', it may indicate the second repetitive PDCCH transmitted on the second CORESET. In general, a terminal can obtain the number of CORESETs corresponding to repetitive PDCCHs in which time-frequency domain resources in a single slot completely overlap. If the number of overlapping repetitive PDCCHs is X, information included in DCI can have a size of ceil(log2(X)) bits. Each code point indicated by ceil(log2(X)) bits can indicate a CORESET ID corresponding to the overlapping repetitive PDCCH. For example, the lowest value of the code point can indicate the lowest ID among the CORESET IDs corresponding to the overlapping repetitive PDCCHs. The value of the code point can indicate the CORESET ID in ascending order. The CORESET ID is a value set in a higher layer, and the base station can transmit CORESET information including the CORESET ID to the terminal.

[0249] The third information included in the DCI may be information (value) indicating a search space ID corresponding to a repetitive PDCCH. For example, when a first repetitive PDCCH is transmitted in a first search space and a second repetitive PDCCH is transmitted in a second search space, there may be a case where the first repetitive PDCCH and the second repetitive PDCCH completely overlap in a time-frequency resource region of a single slot. In this case, the DCI may include an indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. When the repetitive PDCCH is of two types, a first repetitive PDCCH and a second repetitive PDCCH, the DCI may include a 1-bit indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. Specifically, when the value indicated by the 1-bit indicator is '0', it may indicate the first repetitive PDCCH corresponding to the first search space, and when the value of the indicator is '1', it may indicate the second repetitive PDCCH corresponding to the second search space. In general, a terminal can obtain the number of search spaces corresponding to repetitive PDCCHs in which time-frequency domain resources in a single slot completely overlap. If the number of search spaces corresponding to the overlapping repetitive PDCCHs is X, information included in the DCI can have a size of ceil(log2(X)) bits. Each code point indicated by ceil(log2(X)) bits can indicate a search space ID corresponding to the overlapping repetitive PDCCHs. For example, the lowest value of the code point can indicate the lowest ID among the search space IDs corresponding to the overlapping repetitive PDCCHs. The values ​​of the code points can indicate the search space ID in ascending order. The search space ID is a value set in a higher layer, and the base station can transmit search space information including the search space ID to the terminal.

[0250] The fourth information included in the DCI may be information (value) indicating a repetitive PDCCH ID corresponding to a repetitive PDCCH. For example, when a first repetitive PDCCH has a first repetitive PDCCH ID and a second repetitive PDCCH has a second repetitive PDCCH ID, the first repetitive PDCCH and the second repetitive PDCCH may completely overlap in a time-frequency resource region in a single slot. In this case, the DCI may include an indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. When the repetitive PDCCH is of two types, a first repetitive PDCCH and a second repetitive PDCCH, the DCI may include a 1-bit indicator for distinguishing between the first repetitive PDCCH and the second repetitive PDCCH. Specifically, when the value indicated by the 1-bit indicator is '0', it may indicate a first repetitive PDCCH having a first repetitive PDCCH ID, and when the value of the indicator is '1', it may indicate a second repetitive PDCCH having a second repetitive PDCCH ID. In general, a terminal can obtain the number of repetitive PDCCH IDs corresponding to repetitive PDCCHs in which time-frequency domain resources in a single slot completely overlap. If the number of repetitive PDCCH IDs corresponding to the overlapping repetitive PDCCHs is X, information included in the DCI can have a size of ceil(log2(X)) bits. Each code point of ceil(log2(X)) bits can represent a repetitive PDCCH ID corresponding to the overlapping repetitive PDCCHs. The lowest value of the code point can represent a repetitive PDCCH ID among the IDs of the overlapping repetitive PDCCHs. The values ​​of the code points can represent the repetitive PDCCH IDs in ascending order. The repetitive PDCCH ID can be a value set in a higher layer. For example, the number of repetitive PDCCH candidates monitored by the terminal per aggregation level and CCE aggregation level can be set based on search space information that the base station transmits to the terminal.In addition, a unique repetitive PDCCH ID may be set for each repetitive PDCCH candidate monitored by the terminal. The repetitive PDCCH ID may be a value acquired by the terminal based on CORESET information and / or search space information received by the terminal from the base station. For example, based on the search space information, the CCE aggregation level and the number of repetitive PDCCH candidates monitored by the terminal per CCE aggregation level may be set, and a lower CCE aggregation level may be mapped to the lowest repetitive PDCCH ID, and the CCE aggregation levels and repetitive PDCCH IDs may be sequentially mapped. When the base station configures the terminal to monitor multiple repetitive PDCCH candidates of the same CCE aggregation level, the repetitive PDCCH ID may be determined based on a value of at least one of a CCE index, a REG index, or a PRB index to which the repetitive PDCCH is mapped. The repetitive PDCCH ID may correspond to a value of at least one of a CCE index, a REG index, or a PRB index to which the PDCCH is mapped, and may be mapped in an ascending order. The repeated PDCCH ID corresponds to the search space ID and can be mapped in ascending order. In addition, the repeated PDCCH ID corresponds to the CORESET ID and can be mapped in ascending order.

[0251] The fifth information included in the DCI may be information (value) indicating an index of a slot or symbol at which transmission of a repetitive PDCCH starts. For example, a first repetitive PDCCH may be transmitted from slot n, and a second repetitive PDCCH may be transmitted from slot n+1. Since the first repetitive PDCCH and the second repetitive PDCCH start transmission in different slots, the fifth information may be an index of a slot at which transmission of the first repetitive PDCCH and the second repetitive PDCCH starts. The first repetitive PDCCH may be transmitted from symbol m of a specific slot, and the second repetitive PDCCH may be transmitted from symbol m+1 of a specific slot. Since the first repetitive PDCCH and the second repetitive PDCCH start transmission from different symbols, the fifth information may be an index of a symbol at which transmission of the first repetitive PDCCH and the second repetitive PDCCH starts.

[0252] The sixth information included in the DCI may be information (value) indicating an index of a slot or symbol at which transmission of a repetitive PDCCH ends. For example, a first repetitive PDCCH may start transmission from slot n and end transmission from slot n+3, and a second repetitive PDCCH may start transmission from slot n+1 and end transmission from slot n+2. Since the first repetitive PDCCH and the second repetitive PDCCH end transmission in different slots, the sixth information may be an index of a slot at which transmission of the first repetitive PDCCH and the second repetitive PDCCH ends. The first repetitive PDCCH may start transmission from symbol m of a specific slot and end transmission from symbol m+3 of the specific slot, and the second repetitive PDCCH may start transmission from symbol m+1 of a specific slot and end transmission from symbol m+2 of the specific slot. Since the first repetition PDCCH and the second repetition PDCCH are transmitted at different symbols, the sixth information may be an index of a symbol at which the transmission of the first repetition PDCCH and the second repetition PDCCH is terminated.

[0253] Since the size of the bits indicating the fifth and sixth information may be limited, the index of the slot or symbol indicated by the fifth and sixth information may be information (value) after performing a modular operation. For example, if the size of the limited bit is N bits, the remainder (slot index mod 2^N) obtained by dividing the slot index by 2^N may be included in the DCI. The method for determining N is as follows. In a situation where the terminal must distinguish between different repetitive PDCCHs, the number of slots in which the transmission of the different repetitive PDCCHs starts may be obtained. For example, when the first repetitive PDCCH starts transmitting from slot n, the second repetitive PDCCH starts transmitting from slot n+1, and the first repetitive PDCCH and the second repetitive PDCCH completely overlap in the time-frequency domain resources in one slot, the terminal may determine the number of slots (X) in which the repetitive PDCCH starts to be 2. At this time, N can be calculated as N = ceil(log2(X)).

[0254] Multiple, different, repetitive PDCCHs can overlap slots depending on the monitoring period and offset. In this case, adding a separate field to the DCI to address the overlapping slots could result in increased overhead. As mentioned above, repetitive PDCCHs are used in situations where the wireless channel conditions are poor, such as cell-edge UEs, so increasing the DCI overhead is inefficient. Therefore, a method to address this issue is described below.

[0255] ii) Second method

[0256] The second method involves reinterpreting one or more fields included in an existing DCI to obtain information for distinguishing overlapping repetitive PDCCHs. If a terminal needs to distinguish between different repetitive PDCCHs for which it has successfully received a repetitive PDCCH, it can distinguish the repetitive PDCCH by reinterpreting one or more fields of the DCI included in the successfully received PDCCH.

[0257] The field used for reinterpretation may be the RV (redundancy version) field. That is, the terminal can obtain the information necessary to distinguish between different repetitive PDCCHs from the RV field of the DCI. Specifically, the terminal can distinguish between different repetitive PDCCHs by assuming the value of the RV field to be a specific value (e.g., 0).

[0258] The field used for reinterpretation may be a field that carries a TPC command. That is, the terminal can obtain the information necessary to distinguish between different repetitive PDCCHs from the field carrying the TPC command. Specifically, the terminal can distinguish between different repetitive PDCCHs by assuming the value of the TPC command field to be a specific value (e.g., 0 dB).

[0259] The field used for reinterpretation may be the DAI (downlink assignment index) field. That is, the terminal can obtain the information necessary to distinguish between different repetitive PDCCHs from the DAI field. Specifically, the terminal can distinguish between different repetitive PDCCHs by assuming a specific DAI value. For example, since the terminal does not know the DAI value, it may assume the lowest or highest DAI value. Furthermore, since the terminal does not know the DAI value, the terminal may not perform HARQ-ACK multiplexing according to the DAI.

[0260] It should be noted that other fields besides those described above can be used to distinguish different repetitive PDCCHs. In this case, the fields used to distinguish different repetitive PDCCHs may be configured by higher layers. Furthermore, only some bits in the field can be used for reinterpretation, while the remaining bits can be used for conventional purposes. In this case, some bits may be MSBs (most significant bits).

[0261] iii) Third method

[0262] The third method is a method of distinguishing using CRC, rather than adding a separate field to the DCI or reinterpreting the existing DCI field as in the first and second methods described above. That is, information for distinguishing different repetitive PDCCHs can be transmitted to the terminal through DCI scrambled with different CRC values. Specifically, the DCI can be scrambled using a specific RNTI value as the CRC depending on the purpose. The terminal can determine whether the DCI has been successfully received based on the RNTI value according to the CRC value of the DCI. Accordingly, the base station can generate a separate RNTI (hereinafter, referred to as a first RNTI) based on the information for distinguishing different repetitive PDCCHs and the RNTI value, and then use the first RNTI as the CRC of the DCI. The terminal can compare the CRC value of the received DCI with the first RNTI values ​​to determine whether the DCI has been successfully received and obtain information for distinguishing different repetitive PDCCHs. For example, if the information for distinguishing different repetitive PDCCHs has a size of X bits, the base station can generate a first RNTI value by performing an XOR (exclusive OR) operation on the X bits of the RNTI. At this time, the X bits of the RNTI may be the MSB (most significant bits) or LSB (least significant bits) of the RNTI. In addition, the terminal can also calculate available first RNTI values. If the information for distinguishing different repetitive PDCCHs has a size of X bits, the combinations available for the first RNTI are 0 to 2^X-1, which is 2^X. The terminal can compare the CRC of the received DCI with the 2^X first RNTI values ​​to determine a matching first RNTI value. If there is a matching first RNTI value, the terminal can confirm that the information corresponding to the first RNTI value, that is, the information for distinguishing different repetitive PDCCHs, is included in the DCI.

[0263] iv) Fourth method

[0264] The fourth method involves pre-configuring the terminal with a specific value for information used to distinguish between different repetitive PDCCHs. Specifically, the specific value may be the lowest or highest value set for the terminal among the values ​​that the information used to distinguish between different repetitive PDCCHs can indicate.

[0265] Information for distinguishing different repetitive PDCCHs may be a value corresponding to the number of times the repetitive PDCCH is repeatedly transmitted. Therefore, if a specific value set to the terminal is the lowest value, the terminal can assume that it has received a repetitive PDCCH with the lowest number of repetitive transmissions among the numbers of repetitive transmissions of different repetitive PDCCHs. If a specific value set to the terminal is the highest value, the terminal can assume that it has received a repetitive PDCCH with the highest number of repetitive transmissions among the numbers of repetitive transmissions of different repetitive PDCCHs.

[0266] Information for distinguishing different repetitive PDCCHs may be the CORESET ID corresponding to the repetitive PDCCH. Accordingly, if the specific value set to the terminal is the lowest value, the terminal can assume that the repetitive PDCCH was received on the CORESET with the lowest ID among the CORESETs corresponding to the different repetitive PDCCHs. If the specific value set to the terminal is the highest value, the terminal can assume that the repetitive PDCCH was received on the CORESET with the highest ID among the CORESETs corresponding to the different repetitive PDCCHs.

[0267] Information for distinguishing different repetitive PDCCHs may be the search space ID corresponding to the repetitive PDCCH. Accordingly, if the specific value set to the terminal is the lowest value, the terminal can assume that the repetitive PDCCH was received in the search space with the lowest ID among the search space IDs corresponding to the different repetitive PDCCHs. If the specific value set to the terminal is the highest value, the terminal can assume that the repetitive PDCCH was received in the search space with the highest ID among the search space IDs corresponding to the different repetitive PDCCHs.

[0268] Information for distinguishing different repetitive PDCCHs may be the repetitive PDCCH ID corresponding to the repetitive PDCCH. Accordingly, if the specific value set to the terminal is the lowest value, the terminal can assume that it has received the repetitive PDCCH with the lowest ID among the repetitive PDCCH IDs corresponding to the different repetitive PDCCHs. If the specific value set to the terminal is the highest value, the terminal can assume that it has received the repetitive PDCCH with the highest ID among the repetitive PDCCH IDs corresponding to the different repetitive PDCCHs.

[0269] v) Method 5

[0270] The fifth method is a method in which a terminal distinguishes different repetitive PDCCHs by using the search space type (type). Specifically, a first repetitive PDCCH corresponds to a first search space of a first type, a second repetitive PDCCH corresponds to a second search space of a second type, and there may be cases in which the first and second types are different. In this case, the terminal may determine that a repetitive PDCCH has been received in either a search space of the first search type or the second search space. The terminal may determine one of the search spaces as follows. If the first search space type is a cell-common search space and the second search space type is a specific terminal search space, the terminal may determine that a repetitive PDCCH has been received in the first search space of the cell-common search space type.

[0271] A repetitive PDCCH transmitted on a cell common search space may include system information and paging information, and may schedule a PDSCH, a PUCCH, and a PUSCH. In addition, a repetitive PDCCH transmitted on a cell common search space may include a dynamic SFI, a downlink preemption indicator, and an uplink cancellation indicator that may be transmitted to a specific terminal or a specific terminal group. Therefore, a repetitive PDCCH transmitted on a cell common search space may be given priority over a repetitive PDCCH transmitted on a specific terminal search space. In addition, since a repetitive PDCCH transmitted on a cell common search space may be received by multiple terminals within a cell, when the multiple terminals interpret the DCI assuming the received repetitive PDCCH to be a terminal-specific search space, each of the multiple terminals may perform different operations. Therefore, in order to prevent a case where each of the multiple terminals performs different operations, a repetitive PDCCH transmitted on a cell common search space may be given priority.

[0272] The first to fifth methods described above represent methods for determining which of different repetitive PDCCHs the DCI received by the terminal is included in. Hereinafter, a method for resolving PDCCH ambiguity is described, in which the terminal does not determine which repetitive PDCCH the DCI received by the terminal is included in, and the terminal does not determine whether the DCI correctly received by the terminal is transmitted through the repetitive PDCCH. Specifically, a method for explicitly or implicitly determining the time point (i.e., the reference slot) for applying the aforementioned K0, K1, and K2 values ​​is described with reference to FIGS. 18 to 20.

[0273] vi) Method 6

[0274] The sixth method is a method in which the base station indicates the index of the slot or symbol to which the values ​​K0, K1, and K2 are applied through the DCI. For example, if the index of the slot or symbol to which the values ​​K0, K1, and K2 are applied is n, the base station can transmit information about n to the terminal by including it in the DCI. If the information about the index of the slot or symbol to which the values ​​K0, K1, and K2 are applied has a size of N bits, the information about n can be included in the DCI as a value obtained by performing a modular operation. Specifically, the information about n can be included in the DCI as a remainder value obtained by dividing the index n by 2^N (n mod 2^N).

[0275] The method for determining the index of the reference slot or symbol to which the UE applies the K0, K1, and K2 values ​​based on the information included in the DCI is as follows. The repetitive PDCCH successfully received by the UE may be configured to be transmitted in slot a, slot a+1, ..., slot a+b-1. Here, a is a non-negative integer, and b is an integer greater than 0. The UE may assume that the PDSCH, PUCCH, and PUSCH cannot be scheduled before the time point at which the last part of the repetitive PDCCH is received. That is, the UE may assume that the PDSCH, PUCCH, and PUSCH are not scheduled before slot a+b-1, which is the last slot among the slots at which the repetitive PDCCH is configured to be transmitted. Therefore, the UE may assume that the time point (reference slot) at which the K0, K1, and K2 values ​​are to be applied is not a slot preceding slot a+b-1.

[0276] The DCI transmitted by the base station to the terminal may include a specific value, and the terminal may determine the points in time that can be a reference slot based on the specific value. For example, if the specific value is c, the terminal may determine slots n+0*2^N+c, slot n+1*2^N+c, slot n+2*2^N+c, ..., slot n+i*2^N+c as candidates for reference slots to which the values ​​K0, K1, and K2 can be applied. Here, c may be one of 0, 1, ..., 2^N-1. In this case, N may be the bit size of information indicating the specific value c. A method for selecting one of the candidates for multiple reference slots is as follows. As described above, slots prior to slot a+b-1 cannot be reference slots, so the terminal may determine any one of the slots after slot a+b-1 as a reference slot. For example, among the candidates for reference slots, the slot that comes first among the slots after slot a+b-1 can be determined as the reference slot.

[0277] Below, with reference to Figure 26, we will look specifically at the method for determining the reference slot.

[0278] FIG. 26 illustrates a method for determining a reference slot according to one embodiment of the present invention.

[0279] Referring to Fig. 26(a), N is 2 bits, and the terminal is instructed to use a specific value as c from the DCI, and at this time, the c value may be 0. Accordingly, the terminal can determine slot candidates that are possible as reference slots as slot n, slot n+4, slot n+8, .... At this time, since the terminal has received DCI included in the repetitive PDCCH transmitted on slot n+1 and slot n+2, the terminal can determine slot n+4, which is the earliest slot among the slots after slot n+1 and slot n+2, as the reference slot. In addition, the terminal can apply the K0, K1, and K2 values ​​based on the determined reference slot.

[0280] Referring to Fig. 26(b), N is 3 bits, and the terminal is instructed to use a specific value c from the DCI, and c can be 0. Accordingly, the terminal can determine slot candidates that can be reference slots as slot n, slot n+8, slot n+16, .... At this time, since the terminal has received DCI included in the repetitive PDCCH transmitted on slot n+1 and slot n+2, the terminal can determine slot n+8, which is the earliest slot among the slots after slot n+1 and slot n+2, as the reference slot. In addition, the terminal can apply the K0, K1, and K2 values ​​based on the determined reference slot.

[0281] The terminal determines reference slot candidates based on specific values ​​included in the DCI. However, since the DCI includes information about specific values, there may be a problem of large overhead. To solve this problem, the DCI may not include information about separate specific values. For example, the terminal may determine slot 0*M+c, slot 1*M+c, slot 2*M+c, ..., slot i*M+c, ... as reference slot candidates. At this time, M and c can be non-negative integer values ​​set in the upper layer, and in particular, c can be 0.

[0282] vii) Seventh method

[0283] When a terminal needs to determine whether a repetitive PDCCH successfully received is a first repetitive PDCCH or a second repetitive PDCCH, the terminal may determine the last slot of the repetitive PDCCH that ends later among the two as a reference slot to which K0, K1, and K2 values ​​can be applied. The terminal may determine the slot in which the last PDCCH among the overlapping repetitive PDCCHs in the time-frequency resource region is configured to be transmitted as a reference slot. In this case, since the repetitive PDCCH is repeatedly transmitted according to the transmission cycle, the last PDCCH may mean the last PDCCH among the repetitive PDCCHs within one cycle. This will be described in detail with reference to FIG. 27 below.

[0284] FIG. 27 illustrates a method for determining a reference slot according to one embodiment of the present invention.

[0285] Referring to FIG. 27, the terminal can determine the last slot in which the first repetition PDCCH is transmitted and the last slot in which the second repetition PDCCH is transmitted from the CORESET information and the search space information set by the base station. The first repetition PDCCH can be configured to be transmitted in slot n, slot n+1, slot n+2, and slot n+3 within one period. The second repetition PDCCH can be configured to be transmitted in slot n+1 and slot n+2 within one period. The terminal can determine the slot that ends later among the slots in which the first repetition PDCCH is transmitted and the slots in which the second repetition PDCCH is transmitted as a reference slot. For example, the first repetition PDCCH is transmitted last in slot n+3 within one period, and the second repetition PDCCH is transmitted last in slot n+2 within one period. Therefore, the terminal can determine the reference slot based on slot n+3.

[0286] The sixth and seventh methods described above can be applied to the PDCCH ambiguity described in FIGS. 20 to 25. For example, when determining a slot to which dynamic SFI is applied or when determining a reference uplink resource, the terminal needs information on the location of the slot or symbol in which the last PDCCH of a repetitive PDCCH containing a successfully received DCI is transmitted. In this case, the location of the slot or symbol in which the last PDCCH is transmitted can be determined using a method similar to the sixth or seventh methods described above.

[0287] Specifically, according to the sixth method, the terminal can determine a candidate slot or symbol set having a certain period. This candidate slot or symbol set can be indicated through DCI or determined in a higher layer. The terminal can determine one slot or symbol among the candidate slots or symbol sets having a certain period based on the last slot or symbol in which the repetitive PDCCH is transmitted. For example, the terminal can select the earliest candidate slot or symbol among the slots or symbols after the last slot or symbol in which the repetitive PDCCH is transmitted among the candidate slots or symbol sets. For example, the terminal can select the earliest slot or symbol among the slots or symbols after the last slot or symbol in which the repetitive PDCCH is transmitted among the candidate slots or symbol sets. The terminal can determine a slot or reference uplink resource to which dynamic SFI is applied from the selected slot or symbol.

[0288] According to the seventh method, the terminal can obtain the index of the last slot or symbol in which the first repetition PDCCH is transmitted and the index of the last slot or symbol in which the second repetition PDCCH is transmitted. The slot or reference uplink resource to which dynamic SFI is applied can be determined based on the later slot / symbol among the last slot / symbol in which the first repetition PDCCH is transmitted and the last slot / symbol in which the second repetition PDCCH is transmitted. As another example, the slot or reference uplink resource to which dynamic SFI is applied can be determined based on the earliest slot / symbol among the last slot / symbol in which the first repetition PDCCH is transmitted and the last slot / symbol in which the second repetition PDCCH is transmitted.

[0289] To determine the reference downlink resource, the terminal needs information on the location of the slot or symbol in which the first PDCCH of the repeated PDCCH containing the successfully received DCI is transmitted. The location of the slot or symbol in which the first PDCCH is transmitted can be determined using a method similar to the sixth or seventh method described above.

[0290] Specifically, similar to the sixth method, the terminal can determine a candidate slot or symbol set having a certain period. The candidate slot and symbol set can be indicated through DCI or determined from a higher layer. The terminal can select one slot or set among the candidate slots or symbol sets based on the first slot or symbol in which the repetitive PDCCH is transmitted. For example, the terminal can select the last slot or symbol among the previous slots or symbols including the first slot or symbol in which the repetitive PDCCH is transmitted among the candidate slots or symbol sets. Additionally, the terminal can select a slot or symbol prior to the first slot or symbol in which the repetitive PDCCH is transmitted among the candidate slots or symbol sets. The terminal can determine a reference downlink resource based on the selected slot or symbol.

[0291] Similar to the seventh method, the terminal can obtain the index of the first slot or symbol in which the first repetition PDCCH is transmitted and the index of the first slot or symbol in which the second repetition PDCCH is transmitted. At this time, the reference downlink resource can be determined based on the earliest slot / symbol among the first slot / symbol in which the first repetition PDCCH is transmitted and the first slot / symbol in which the second repetition PDCCH is transmitted. As another example, the reference downlink resource can be determined based on the latest slot / symbol among the first slot / symbol in which the first repetition PDCCH is transmitted and the first slot / symbol in which the second repetition PDCCH is transmitted.

[0292] viii) Method 8

[0293] The eighth method is a method of transmitting information about repeated transmission of a repeated PDCCH through a specific PDCCH that sets up a repeated PDCCH.

[0294] When a terminal is configured to receive a repetitive PDCCH from a base station, the terminal can monitor and receive a specific PDCCH, thereby explicitly receiving information about the repetitive transmission of the repetitive PDCCH. In this case, the information about the repetitive transmission of the PDCCH may include the first slot (or symbol) in which the transmission of the repetitive PDCCH begins and the number of slots (or symbols) in which the repetitive transmission is performed.

[0295] Information regarding repeated transmission of a repeated PDCCH may be explicitly included in the DCI included in a specific PDCCH. In this case, the specific PDCCH may be expressed as an activation PDCCH, and for convenience of explanation, it is described as a first activation PDCCH in this specification.

[0296] Information regarding repeated transmission of a repeated PDCCH may be explicitly included in the DCI included in the first PDCCH where transmission of the repeated PDCCH begins. In this case, the first PDCCH may be expressed as an activation PDCCH, and for convenience of explanation, it is described as a second activation PDCCH in this specification.

[0297] Information about repeated transmission of a repetitive PDCCH may be explicitly included in the DCI included in the first PDCCH where transmission of the repetitive PDCCH begins and in a specific number of repetitive PDCCHs. In this case, the first PDCCH and the specific number of repetitive PDCCHs may be expressed as an activation repetitive PDCCH. The first PDCCH and the specific number of repetitive PDCCHs may be consecutive repetitive PDCCHs.

[0298] The terminal can obtain information about the repeated transmission of the aforementioned repetitive PDCCH by reinterpreting the existing fields that constitute the DCI. At this time, the DCI can schedule the PDSCH, PUCCH, and PUSCH. The existing fields can include the TDRA field. For example, the SLIV value indicated by the TDRA field can be reinterpreted. By reinterpreting the SLIV value, the terminal can obtain resource information about the repetitive PDCCH that is repeatedly transmitted after the first active PDCCH, the second active PDCCH, and the active repetitive PDCCH.

[0299] Specifically, the TDRA field of the DCI included in the repetitive PDCCH repeatedly transmitted after the first active PDCCH, the second active PDCCH, and the active repetitive PDCCH may include a SLIV value for scheduling the PDSCH, PUCCH, and PUSCH. That is, the terminal may obtain resource information for the repetitive PDCCH, and resource information for the PDSCH, PUCCH, and PUSCH based on the TDRA field of the DCI included in the repetitive PDCCH repeatedly transmitted after the first active PDCCH, the second active PDCCH, and the active repetitive PDCCH. The TDRA fields described in this specification are as shown in Table 4.

[0300]

[0301] Figure 28 illustrates active PDCCH and repetitive PDCCH reception according to one embodiment of the present invention.

[0302] Referring to FIG. 28, if a terminal receives an active PDCCH#1 in slot n, the terminal can expect PDSCH, PUCCH, and PUSCH transmissions in slot n+5. In addition, the terminal can expect repeated PDCCH transmissions for three slots starting from slot n+1. A terminal that receives PDCCH#1A in slot n+1, PDCCH#1B in slot n+2, and PDCCH#1C in slot n+3 can obtain SLIV values ​​for PDSCH, PUCCH, and PUSCH expected to be transmitted in slot n+5.

[0303] When the search spaces for different types of terminals completely overlap in the time-frequency resource domain, the terminal can perform blind decoding to receive the PDCCH in the search space set for the terminal by receiving information about the repeated transmission of the repeated PDCCH.

[0304] The base station can transmit information about the CORESET and the search space to the terminal. Information about the CORESET is described below. In this specification, the resources that constitute the CORESET may have the same meaning as the resources included in the CORESET.

[0305] The first information about the CORESET may be the index of the PRB or PRB sets that constitute the CORESET in which the PDCCH is transmitted. The PRB set may be six consecutive PRBs. The index of the PRB or PRB sets may be set in the form of a bitmap. For example, if the bit value is 1, the PRB or PRB set may correspond to the CORESET for receiving the PDCCH. If the bit value is 0, the PRB or PRB set may not correspond to the CORESET for receiving the PDCCH. The second information about the CORESET may be the number of symbols in which the PDCCH is transmitted. In this case, the number of symbols may be 1, 2, or 3, and the symbols may be consecutive symbols. By receiving information about the CORESET from the base station, the terminal may determine the resource in which the PDCCH is transmitted.

[0306] Specifically, the first information for CORESET may set the indices of PRBs as PRB#(6*n), PRB#(6*n+1), PRB#(6*n+2), PRB#(6*n+3), PRB#(6*n+4), PRB#(6*n+5), where n may be an integer. Specifically, the base station may set the indices of P PRBs as PRB#0, PRB#1, ...., PRB#(P-1), where P may have a value that is a multiple of 6. At this time, the PRBs may or may not be consecutive in the frequency domain. The second information for CORESET is the number of symbols (S) through which the PDCCH is transmitted, where S may be one of 1, 2, and 3. That is, the terminal may receive from the base station a resource through which the PDCCHs are transmitted based on the first information and the second information.

[0307] Resources corresponding to P PRBs and S symbols constituting a CORESET can be configured as a REG (resource element group). One REG can be one PRB and one symbol. That is, P PRBs and S symbols can be configured as P*S REGs. Adjacent 2, 3, or 6 REGs can be bundled to form one REG bundle. The method of bundling 2, 3, or 6 REGs can be determined depending on the length (number of symbols) of the CORESET and the mapping method (interleaved mapping / non-interleaved mapping).

[0308] If the mapping method is non-interleaved and the length of the CORESET is 1 symbol, one REG bundle can be generated by bundling 6 consecutive REGs in the frequency domain. If the mapping method is non-interleaved and the length of the CORESET is 2 symbols, one REG bundle can be generated by bundling 3 REGs in each symbol, for a total of 6 REGs (3 REGs per symbol * 2 symbols). For convenience, when each symbol of the 2 symbols is referred to as symbol A and symbol B, the 3 REGs in symbol A can be consecutive to each other in the frequency domain, and the 3 REGs in symbol B can be consecutive to each other in the frequency domain. In addition, the 3 REGs in symbol A and the 3 REGs in symbol B can be located in the same frequency domain. If it is a non-interleaved mapping method and the length of CORESET is 3 symbols, one REG bundle can be generated by bundling 2 REGs from each symbol, thereby bundling 6 REGs in total (2 REGs per each symbol * 3 symbols). For convenience, when each symbol of the 3 symbols of the length of CORESET is referred to as a C symbol, a D symbol, and an E symbol, the 2 REGs in the C symbol can be consecutive in the frequency domain, the 2 REGs in the D symbol can be consecutive in the frequency domain, and the 2 REGs in the E symbol can be consecutive in the frequency domain. In addition, the 2 REGs in the C symbol, the 2 REGs in the D symbol, and the 2 REGs in the E symbol can be located in the same frequency domain.

[0309] If the mapping method is interleaved and the length of CORESET is 1 symbol, i) a REG bundle can be generated by bundling 6 consecutive REGs in the frequency domain. ii) a REG bundle can be generated by bundling 2 consecutive REGs in the frequency domain. If the mapping method is interleaved and the length of CORESET is 2 symbols, a REG bundle can be generated by bundling 1 REG of each symbol. At this time, 1 REG of each symbol can be located on the same frequency domain. If the mapping method is interleaved and the length of CORESET is 3 symbols, a REG bundle can be generated by bundling 1 REG of each symbol. At this time, 1 REG of each symbol can be located on the same frequency domain.

[0310] A CCE can be generated by bundling REG bundles generated using the above-described method. In this case, the CCE can be composed of six REGs. That is, since the generated REG bundle is composed of two, three, or six REGs, the CCE can be composed of three, two, or one REG bundle. In the case of non-interleaved mapping, the REG bundle is composed of six REGs regardless of the length of the CORESET. In this case, the CCE can be composed of one REG bundle.

[0311] This specification proposes a new CORESET, different from the existing CORSET. The new CORESET can be composed of at least one of a REG, REG bundle, or CCE. The following describes how to construct the new CORESET.

[0312] i) Method A

[0313] A new CORESET can be configured to include at least six consecutive symbols. The base station can transmit information about the CORESET to the terminal and configure a CORESET including six consecutive symbols. At this time, the information about the CORESET can include information about the start symbol and the symbol length (number) for configuring the new CORESET. The terminal can determine the REG, REG bundle, and CCE structure based on the CORESET including the six symbols configured by the base station. For convenience of explanation, the six consecutive symbols are expressed as symbol #0, symbol #1, symbol #2, symbol #3, symbol #4, and symbol #5.

[0314] Figure 29 illustrates the configuration of a control resource set according to one embodiment of the present invention.

[0315] Referring to FIG. 29, REG, REG bundle and CCE can be configured as follows.

[0316] i) A REG can be composed of 12 REs included in 1 PRB of each symbol of 6 symbols. ii) A REG bundle can include 6 REGs of 6 symbols. That is, a REG bundle can be composed of a REG corresponding to symbol #0, a REG corresponding to symbol #1, ..., a REG corresponding to symbol #5. Since one REG is composed of 12 REs, one REG bundle composed of 6 REGs can be composed of 72 REs. iii) A CCE can be composed of one REG bundle. Referring to FIG. 29, the number of REGs constituting a REG bundle is equal to the number of symbols constituting a CORESET. However, when a CCE is composed as shown in FIG. 29, the terminal cannot obtain frequency diversity because each REG bundle constituting the CCE is located in the same PRB. Therefore, when a terminal monitors one CCE, there is a problem of poor PDCCH reception performance.

[0317] Figure 30 illustrates the configuration of a control resource set according to one embodiment of the present invention.

[0318] Referring to FIG. 30, REG, REG bundle and CCE can be configured as follows.

[0319] i) A REG can be composed of 12 REs included in 1 PRB of each symbol. ii) A REG bundle can be composed of S REGs corresponding to S consecutive symbols. A method for determining S consecutive symbols will be described later. One REG bundle can be composed of REs included in S symbols of 1 PRB (i.e., 12*S REs). At this time, the value of S can be any one of 1, 2, and 3, and can be a value set in a higher layer. The 6 consecutive symbols that make up the CORESET can be divided into 6 / S symbol sets. At this time, each symbol set can include S consecutive symbols. For example, the first symbol set among the 6 / S symbol sets can include symbol#0, symbol#1, …, symbol#(S-1), and the second symbol set can include symbol#S, symbol#(S+1), …, symbol#(2*S-1). Hereafter, the symbol set can also include S sequential symbols. iii) CCE can be composed of 6 / S REG bundles. At this time, the CCE can be composed of one REG bundle selected from each symbol set. The index of the REG bundle can be set for each symbol set. And the terminal can configure the CCE by selecting a REG bundle with the same index from each symbol set. The index of the REG bundle in each symbol set can be interleaved. Meanwhile, an index can be set for all REG bundles that constitute the CORESET. CCE can be composed of 6 / S consecutive REG bundles among the set indexes. That is, CCE x can be composed of REG bundle#(6 / S*x), REG bundle#(6 / S*x+1), REG bundle #(6 / S*x+6 / S-1). The method for setting the index of the REG bundle is as follows. Among the six symbols that make up CORESET, the REG bundle corresponding to the symbol that is most chronologically advanced can be indexed.Among the PRBs that constitute the CORESET, the REG bundles that constitute the PRB located in the lowest frequency region can be indexed based on the time domain, and then the REG bundles included in the PRB located in the next lower frequency region can be indexed in the time domain. At this time, the indexed indices can be interleaved.

[0320] ii) Method B

[0321] A new CORESET may be composed of multiple base CORESETs. A base CORESET may consist of 1 to 3 consecutive symbols. That is, a base station may transmit information about a new CORESET to a terminal, and at this time, the information about the new CORESET may include information about the number of base CORESETs that constitute the new CORESET and information about the number of symbols (1 to 3 consecutive symbols) that constitute the base CORESET.

[0322] Figure 31 illustrates a control resource set composed of a basic control resource set according to one embodiment of the present invention.

[0323] Referring to Fig. 31, four base CORESETs (base CORESET#0, #1, #2, #3) can each be composed of two symbols. A new CORESET can be composed of four base CORESETs. In Fig. 31, the four base CORESETs are illustrated as being composed of the same length (number of symbols) and the same frequency band, but each base CORESET can be composed of different lengths and frequency bands. In addition, each base CORESET is located continuously in the time domain resource, but is not limited thereto and can be discontinuous.

[0324] Below, a method for determining multiple basic CORESETs and the arrangement of symbols constituting multiple basic CORESETs are described.

[0325] The symbols that constitute multiple basic CORESETs may be consecutive in the time domain. Meanwhile, the terminal may receive the starting symbol indices of multiple basic CORESETs from the base station. For example, the terminal may receive a bitmap of size (length) 14 bits. In this case, the MSB of the bitmap may indicate the first symbol of the slot as the starting symbol index, and the LSB of the bitmap may indicate the last symbol of the slot as the starting symbol index.

[0326] Figure 32 illustrates a control resource set consisting of a basic control resource set according to one embodiment of the present invention.

[0327] Referring to Fig. 32, a 14-bit bitmap may be [10010000101000]. At this time, the index of the symbol corresponding to 1 in the bitmap may be 0, 3, 8, 10. Therefore, the basic control resource set may be configured to start from symbols 0, 3, 8, 10.

[0328] A terminal can receive a bitmap of size 14*N bits from a base station. The bitmap can indicate the starting symbol index for N slots. Specifically, the bitmap can be divided into 14-bit groups, where the MSB of each 14-bit group can indicate the starting symbol index of the first symbol of the slot, and the LSB can indicate the starting symbol index of the last symbol of the slot.

[0329] Figure 33 illustrates a method for designing a control resource set using a basic control resource set according to one embodiment of the present invention.

[0330] Referring to FIG. 33, the base station can transmit a bitmap with a length of 28 to the terminal. At this time, the first 14 bits can indicate the position of the basic CORESET start symbol in the first slot, and the next 14 bits can indicate the position of the basic CORESET start symbol in the second slot. Since the first 14 bits are [10010000000000], the basic CORESET can be configured from symbols 0 and 3 of the first slot. Since the next 14 bits are [1010000000000], the basic CORESET can be configured from symbols 0 and 2 of the second slot.

[0331] Each of the multiple basic CORESETs can be composed of different symbol lengths (number of symbols). The base station can transmit to the terminal the location and length of the starting symbol that constitutes the basic CORESET within a single slot. The location and length of the starting symbol can be set as a pair. Furthermore, the frequency ranges of the multiple basic CORESETs can all be identical.

[0332] FIG. 34 illustrates a method for configuring a control resource set using a basic control resource set according to one embodiment of the present invention.

[0333] Meanwhile, the frequency domains of the multiple base CORESETs may be different from each other. Referring to FIG. 34, a new CORESET may be composed of four base CORESETs. In this case, the multiple base CORESETs may be composed of resources in different frequency domains. For example, the first base CORESET (base CORESET#0) may be composed of the remaining PRBs excluding the six lowest PRBs in the frequency domain. The second base CORESET (base CORESET#1) may be composed of the remaining PRBs excluding the six highest PRBs in the frequency domain. The third base CORESET (base CORESET#2) and the fourth base CORESET (base CORESET#3) may be composed of the remaining PRBs excluding the six middle PRBs. In this way, since each of the base CORESETs is composed of resources in different frequency domains, it is advantageous in terms of frequency diversity.

[0334] Below, a method for configuring each of the basic CORESETs is described when each of the basic CORESETs is composed of resources in different frequency domains.

[0335] The base station can configure the frequency resources of each basic CORESET using different bitmaps. For example, there may be a bitmap corresponding to each of multiple basic CORESETs, and each bitmap may indicate whether six PRBs, bundled together, constitute the basic CORESET. The number of PRBs constituting each basic CORESET may be the same.

[0336] The base station can set frequency domain resources with two different bitmaps, such that the frequency domain resources of the odd-numbered basic CORESET are indicated with the first bitmap, the frequency domain resources of the even-numbered basic CORESET are indicated with the second bitmap, and the frequency domain resources of the second basic CORESET are indicated with the second bitmap. Generalizing this, the base station can indicate the frequency domain resources of the basic CORESET to the terminal with B different bitmaps. At this time, if n mod B is 0, the frequency domain resources of the basic CORESET n can be indicated with the first bitmap, and if n mod B is 1, the frequency domain resources of the basic CORESET n can be indicated with the second bitmap. In other words, if n mod B is k, the frequency domain resources of the basic CORESET can be indicated with the k+1-th bit of the bitmap. At this time, n can be indexed from 0 as the index of the basic CORESET.

[0337] The base station can transmit to the terminal a PRB offset value between the basic CORESETs. For example, the frequency domain resources of an odd basic CORESET among multiple basic CORESETs can be indicated by a bitmap. In this case, the bitmap can indicate whether the six bundled PRBs are included in the odd basic CORESET. In addition, the base station can transmit to the terminal a PRB offset. The PRB offset can be in units of six PRBs. The PRBs included in the even basic CORESET can be PRBs corresponding to an index value obtained by adding the PRB offset to the indices of the PRBs included in the odd basic CORESET.

[0338] When a base station configures a new CORESET for a terminal, the terminal can receive PDCCHs in each basic CORESET. The following describes how a terminal receives PDCCHs.

[0339] The indices of CCEs of a basic CORESET may be indexed in a frequency-first manner. That is, among the basic CORESETs that constitute a new CORESET, the CCEs included in the basic CORESET that is earliest in the time domain are selected first, and the selected CCEs may be indexed in ascending order in the frequency resource domain. At this time, if the number of first CCEs included in the basic CORESET that is earliest in the time domain is N_CCE0, each of the first CCEs may be indexed as 0, 1, ..., N_CCE0-1 in ascending order in the frequency domain. The second CCEs included in the basic CORESET that is second earliest in the time domain may be indexed in ascending order in the frequency domain. The indices of the second CCEs may be indexed as values ​​after the last index of the first CCEs in the time domain. If the number of CCEs included in the second CCEs is N_CCE1, each of the second CCEs can be indexed as N_CCE0, N_CCE0+1, …, N_CCE0+N_CCE1-1 in ascending order in the frequency domain. In the same manner, the CCEs of the basic CORESET that constitute the new CORESET can be indexed.

[0340] Meanwhile, the CCEs of each basic CORESET constituting the new CORESET may be indexed in a time-first manner. For example, among the basic CORESETs constituting the new CORESET, the CCEs constituting the PRB in the lowest frequency domain may be selected first, and the selected CCEs may be indexed in ascending order in the time domain. At this time, if the number of the first CCEs constituting the PRB in the lowest frequency domain is N_CCE0, each of the first CCEs may be indexed as 0, 1, …, N_CCE0-1 in ascending order in the time domain. The second CCEs constituting the second-lowest PRB in the frequency domain may be indexed in ascending order in the time domain. The indices of the second CCEs may be indexed as values ​​after the last index of the first CCEs in the frequency domain. If the number of secondary CCEs is N_CCE1, each of the secondary CCEs can be indexed as N_CCE0, N_CCE0+1, …, N_CCE0+N_CCE1-1 in ascending order in the time domain. In the same way, the CCEs of the base CORESET that constitute the new CORESET can be indexed.

[0341] FIG. 35 illustrates a method for indexing CCE in a frequency-priority manner according to one embodiment of the present invention.

[0342] Referring to FIG. 35, each base CORESET constituting a new CORESET may include eight CCEs. At this time, the CCEs corresponding to the first base CORESET (base CORESET#0) located at symbols 0 and 1 may be indexed as 0, 1, 2, 3, 4, 5, 6, and 7 in a frequency-first manner. The CCEs corresponding to the second base CORESET (base CORESET#1) located at symbols 2 and 3 may be indexed as 8, 9, 10, 11, 12, 13, 14, and 15 in a frequency-first manner. The CCEs of the remaining base CORESETs constituting the new CORESET may also be indexed in the same manner.

[0343] FIG. 36 illustrates a method for indexing CCE in a time-first manner according to one embodiment of the present invention.

[0344] Referring to Fig. 36, each PRB included in a new CORESET may be composed of four CCEs. At this time, the CCEs in the lowest frequency range may be indexed as 0, 1, 2, and 3 in a time-first manner. The CCEs in the second lowest frequency range may be indexed as 4, 5, 6, and 7 in a time-first manner. The CCEs of the remaining basic CORESETs that constitute the new CORESET may also be indexed in the same manner.

[0345] The terminal can receive a PDCCH with an aggregation level of L among L CCEs among the CCEs constituting the basic CORESET. In this case, i) L can be a power of 2. For example, L can be a value of 1, 2, 4, 8, 16, 32, etc. In addition, ii) L can be a value of 2^k * C. k is a natural number, and C is the number of basic CORESETs, which can be a natural number. For example, if a new CORESET is composed of 3 basic CORESETs, L can have a value of 1*3, 2*3, 4*3, 8*3, 16*3, 32*3, etc.

[0346] FIG. 37 illustrates a PDCCH candidate based on a CCE indexed in a frequency-priority manner according to an embodiment of the present invention, and FIG. 38 illustrates a PDCCH candidate based on a CCE indexed in a time-priority manner according to an embodiment of the present invention.

[0347] Referring to FIG. 37, the CCEs constituting a new CORESET can be indexed in a frequency-first manner. At this time, the region where the terminal monitors PDCCH candidates may be CCE 12 to CCE 23 (12 CCEs). Based on the CCE index, the terminal can recognize that the CCEs for which it must monitor PDCCH candidates are the four CCEs included in the second base CORESET (base CORESET#1) and all CCEs included in the third base CORESET (base CORESET#2).

[0348] Referring to Figure 38, the CCEs that constitute a new CORESET can be indexed in a time-first manner. At this time, the area where the terminal monitors PDCCH candidates may be CCE 12 to CCE 23 (12 CCEs). Based on the CCE index, the terminal can recognize that the CCEs that must monitor PDCCH candidates are three CCEs from each of the four basic CORESETs.

[0349] The CCEs of the basic CORESETs that constitute a new CORESET can be independently indexed. For example, if the number of CCEs constituting the first basic CORESET among the basic CORESETs that constitute the new CORESET is N_CCE0, the CCEs constituting the first basic CORESET can be indexed with one of the values ​​0, 1, ...., N_CCE0-1, respectively. Similarly, if the number of CCEs constituting the second basic CORESET among the basic CORESETs that constitute the new CORESET is N_CCE0, the CCEs constituting the second basic CORESET can be indexed with one of the values ​​0, 1, ...., N_CCE0-1, respectively. At this time, the terminal can determine the CCEs on which the PDCCH is received on the first basic CORESET. The terminal can receive a PDCCH having an aggregation level L from L CCEs among the CCEs that constitute the first basic CORESET. The terminal can receive a PDCCH with an aggregation level of L from L CCEs among the CCEs constituting the second CORESET. At this time, the PDCCH received on the first CORESET and the PDCCH received on the second CORESET may include the same DCI. That is, the terminal can repeatedly receive the PDCCH on different basic CORESETs constituting the new CORESET. Here, L may be a value that is a power of 2. For example, L may have values ​​such as 1, 2, 4, 8, 16, and 32.

[0350] Figure 39 illustrates that a PDCCH is repeatedly received on a basic control resource set according to one embodiment of the present invention.

[0351] Referring to FIG. 39, the CCEs of the base CORESETs constituting a new CORESET can be independently indexed. The terminal can receive a first PDCCH with an aggregation level of 4 on the first base CORESET (base CORESET#0). At this time, the region that the terminal monitors to receive the PDCCH with an aggregation level of 4 may be CCE2, CCE3, CCE4, and CCE5 included in the first base CORESET (base CORESET#0). The terminal can receive a second PDCCH with an aggregation level of 4 on the second base CORESET (base CORESET#1). At this time, the region that the terminal monitors to receive the PDCCH with an aggregation level of 4 may be CCE2, CCE3, CCE4, and CCE5 included in the second base CORESET (base CORESET#1). Similarly, the terminal can receive the third PDCCH and the fourth PDCCH on the third base CORESET (base CORESET#2) and the fourth base CORESET (base CORESET#3), respectively. At this time, the DCIs included in the first, second, third, and fourth PDCCHs may be identical. That is, the terminal can monitor and receive a PDCCH including a single identical DCI through 16 CCEs.

[0352] When REGs and REG bundles form a CCE, different interleaving can be applied to each basic CORESET. This is to distribute the CCEs included in each basic CORESET across different frequency bands. This facilitates multiplexing between one basic CORESET and another basic CORESET that overlaps it.

[0353] Below, we describe how to apply interleaving to each basic CORESET. First, if the index of the REG bundle that constitutes the basic CORESET is x, the index of the interleaved REG bundle can be f(x). f(x) is as shown in Mathematical Expression 1.

[0354]

[0355] N in mathematical expression 1 REG CORESET is the number of REGs that constitute the basic CORESET, and L may be the number of REGs that constitute the REG bundle. Therefore, N REG CORESET / L can be the number of REG bundles in the base CORESET. R can be one of the values ​​2, 3, or 6. n shift may be a shift value applied when interleaving is performed for the indices of REG bundles that constitute each basic CORESET. n shift Based on n, the indices of REG bundles can be interleaved differently. shift It can be a value set by the base station to the terminal or a cell ID.

[0356] The base station applies n to each basic CORESET to interleave the indices of different REG bundles of different basic CORESETs. shift The value can be set differently for each basic CORESET. The terminal can set n for each basic CORESET. shift You can interleave the indices of REG bundles based on values.

[0357] The base station provides the terminal with one value (n shift,0 ) can be set. At this time, the terminal is n shift,0 The values ​​can be applied differently for each basic CORESET. For example, the terminal can be n shift,0 Multiple of the value n shiftThe index of the REG bundle can be interleaved by determining the value. In addition, the terminal is n shift,0 Add a value based on the number of REG bundles to the value n shift You can determine the value. For example, n shift The value is n shift,0 +N REG CORESET / L / N*n can be determined. Here, N is the number of basic CORESETs that constitute a new CORESET, and n is the index of the basic CORESET, which can be a value of 0, 1 ..., N-1. The terminal is n shift,0 +N REG CORESET If the value of / L / N*n is not an integer, then the integer value obtained by applying one of the rounding operations, up, down, or up, is n. shift,0 +N REG CORESET / L / N*n can be determined by the value. This means that the index of CCEs is n evenly distributed according to the number of REG bundles. shift This is a method that sets the difference by the value.

[0358] FIG. 40 illustrates a terminal according to one embodiment of the present invention repeatedly receiving PDCCH candidates by applying interleaving to a basic control resource set.

[0359] Fig. 40 is an example of a method for determining the index of the CCEs constituting each base CORESET using different interleaving for each base CORESET when the CCEs of the base CORESETs constituting the new CORESET are independently indexed as described above. Referring to Fig. 40, the first base CORESET (base CORESET#0) has n shift n as a value shift,0 +N REG CORESET / L / N*0 is used, and n is used for the second base CORESET (base CORESET#1). shift n as a value shift,0 +N REG CORESET / L / N*1 is used, and n is used for the third base CORESET (base CORESET#2) shift n as a value shift,0 +N REG CORESET / L / N*2 is used, and n is used for the 4th base CORESET (base CORESET#3) shift n as a value shift,0 +N REG CORESET / L / N*3 can be used. In this case, L is 6, N is 4, N REG CORESET Silver is 48, R is 2, n shift,0 can be 0. Different n for different base CORESETs shift Since the values ​​are applied, the interleaving can be different for each base CORESET. In addition, the CCE 0 of each base CORESET can be located in the lowest frequency range for the first base CORESET (base CORESET#0), in the frequency range corresponding to 1 / 4 of the entire frequency band for the second base CORESET (base CORESET#1), in the frequency range corresponding to 2 / 4 of the entire frequency band for the third base CORESET (base CORESET#2), and in the frequency range corresponding to 3 / 4 of the entire frequency band for the fourth base CORESET. Therefore, the CCE0 of each base CORESET can be equally distributed in the frequency band.

[0360] Referring to FIG. 40, a terminal can receive a PDCCH having an aggregation level of 4 on a first base CORESET (base CORESET#0). At this time, the areas that the terminal monitors to receive the PDCCH having an aggregation level of 4 may be CCE2, CCE3, CCE4, and CCE5 of the first base CORESET. Similarly, the terminal can receive a PDCCH having an aggregation level of 4 by monitoring CCE2, CCE3, CCE4, and CCE5 of the second base CORESET, the third base CORESET, and the fourth base CORESET, respectively. At this time, the PDCCHs having an aggregation level of 4 received on the first base CORESET, the second base CORESET, the third base CORESET, and the fourth base CORESET, respectively, may include the same DCI. Since different interleaving is applied to each basic CORESET, CCE2, CCE3, CCE4, and CCE5 of each basic CORESET can be distributed and arranged in the frequency domain. Therefore, this method is efficient in terms of frequency diversity.

[0361] Below, a method for a terminal to receive a PDCCH is described. At this time, the PDCCH can be transmitted on a CORESET, which can be an existing CORESET or the new CORESET described above.

[0362] iii) Method C

[0363] A base station can transmit to a terminal information about one CORESET and information about multiple search spaces corresponding to one CORESET. Each of the multiple search spaces can have a period and an offset. At this time, the period and offset can be set on a slot basis. The information about the multiple search spaces can include information about the index of a start symbol for which the terminal monitors to receive a PDCCH within a slot. The terminal can monitor and receive a PDCCH in a region determined based on the period and offset of each of the multiple search spaces and the index of the start symbol received from the base station. That is, the terminal can receive a PDCCH on each of the multiple search spaces corresponding to one CORESET. At this time, the DCI included in each PDCCH received on the multiple search spaces can be identical. Therefore, the PDCCH can be repeatedly transmitted.

[0364] A base station may set an index for each of a plurality of search spaces in order to transmit a PDCCH including the same DCI to a terminal in multiple search spaces. That is, the terminal may recognize that the indexed search spaces set by the base station transmit the same DCI. For example, the terminal may receive search space 1 and search space 2 from the base station, and the terminal may recognize that the DCI included in the PDCCH repeatedly transmitted in search space 1 and search space 2 are the same. At this time, the period of search space 1 and the period of search space 2 may be the same. That is, by setting the periods of multiple search spaces transmitting the same DCI to be the same, the terminal may determine the section (resource region) in which the PDCCH is repeatedly transmitted. For example, if the period of search space 1 and the period of search space 2 are the same as P, the terminal may determine the slot index as P*n, P*n+1, …. , P*n+P-1 slots are determined as sections in which PDCCHs are repeatedly transmitted, and PDCCHs including the same DCI can be repeatedly transmitted in multiple search spaces included in the determined sections. At this time, n can have a value of 0, 1, 2, ...

[0365] Figure 41 illustrates that a PDCCH is repeatedly transmitted on multiple search spaces according to one embodiment of the present invention.

[0366] Referring to FIG. 41, two search spaces can be set in one CORESET. The period of the first search space (search space#A) among the two search spaces can be 4 slots and the offset can be 0 slots. Therefore, the terminal can perform monitoring to receive a PDCCH on the first search space (search space#A) of slots 0, 4, and 8. The period of the second search space (search space#B) among the two search spaces can be 4 slots and the offset can be 1 slot. Therefore, the terminal can perform monitoring to receive a PDCCH on the second search space (search space#B) of slots 1, 5, and 9. When a terminal is configured to repeatedly receive a PDCCH including the same DCI on multiple search spaces, the terminal can receive a repeated PDCCH including the same DCI on the search spaces of slot 0, slot 1, slot 2, and slot 3 based on a common period (the period of the first search space and the second search space). In addition, the terminal can receive a repeated PDCCH conveying the same DCI on the search spaces of slot 4, slot 5, slot 6, and slot 7 based on the common period.

[0367] Meanwhile, the period of the first search space and the period of the second search space may be different from each other. In this case, the resource region (section) in which the PDCCH is repeatedly transmitted needs to be defined. The section in which the PDCCH is repeatedly transmitted can be determined based on the least common multiple of the periods of the first search space and the second search space. The section in which the PDCCH is repeatedly transmitted can be determined based on the greatest common divisor of the periods of the first search space and the second search space. The section in which the PDCCH is repeatedly transmitted can be determined based on the larger period between the periods of the first search space and the second search space. The section in which the PDCCH is repeatedly transmitted can be determined based on the smaller period between the periods of the first search space and the second search space. The base station can separately transmit (set) the period of the section in which the PDCCH is repeatedly transmitted to the terminal.

[0368] A base station can transmit (configure) multiple periods and offset values ​​for a single search space to a terminal. Furthermore, the base station can transmit (configure) the index of the start symbol for which the terminal monitors for receiving PDCCHs on multiple slots. The terminal can receive repeated PDCCHs containing the same DCI based on the multiple periods, offset values, and start symbol indices.

[0369] In order to transmit PDCCHs including the same DCI in a search space, a base station can transmit (configure) to a terminal the period and offset value of one search space. In addition, the base station can transmit (configure) to the terminal the index of a start symbol that should be monitored in order to receive a PDCCH within one slot. In addition, the base station can indicate the number (K) of slots for setting a search space that the terminal repeatedly monitors. The number of slots (K) may be a natural number smaller than the period of the search space. Specifically, a search space that the terminal monitors in order to receive a PDCCH may be set according to the period. The search space may be set based on the index of the start symbol within the slot indicated by the base station. In other words, the search space may be set from the start symbol indicated by the index. In addition, the base station can indicate the number (K) of slots for setting a search space that the terminal repeatedly monitors. For example, if the base station indicates the value of K as 2, the search space may be set identically in slot n and slot n+1. At this time, the index of the symbol where the search space begins may be n, which is the same as the slot index. Therefore, the search space in slot n and slot n+1 may be set starting from symbol n of each slot.

[0370] Figure 42 illustrates a PDCCH being transmitted based on a search space and repetition settings according to one embodiment of the present invention.

[0371] Referring to Fig. 42, the search space period may be 4 slots and the offset may be 0 slots. Accordingly, the search space may be set in slot 0, slot 4, slot 8, .... In addition, the terminal may be instructed to set 2 as the number of slots (K) for repeatedly monitoring the search space. In this case, the search space for the terminal to monitor the repeated PDCCH may be set in the slot (slot 1, slot 5, slot 9, ...) immediately following the slot (slot 0, slot 4, slot 8, ...) in which the first search space is set.

[0372] The base station can transmit (set) to the terminal the period and offset value of one search space. In addition, the base station can transmit (set) K indices of start symbols at which the terminal performs PDCCH monitoring within the slot. Specifically, the terminal can perform monitoring based on the first index of the symbol at which monitoring for receiving a PDCCH starts within slot n. For example, if the first index is 0, the search space is set from the first symbol of slot n, and the terminal can perform monitoring for PDCCH reception on the search space of slot n. The terminal can perform monitoring based on the second index of the symbol at which monitoring for receiving a PDCCH starts within slot n+1. For example, if the second index is 2, the search space is set from the third symbol of slot n+1, and the terminal can perform monitoring for PDCCH reception on the search space of slot n+1.

[0373] FIG. 43 illustrates that a PDCCH is transmitted at different start symbol positions based on a search space and repetition settings according to one embodiment of the present invention.

[0374] Referring to Fig. 43, the search space can be set to have a period of 4 slots and an offset of 0 slots. Therefore, the search space can be set to slot 0, slot 4, slot 8, .... In addition, the base station can set 0 and 7 as the starting symbol index of the search space. Therefore, the search space can be set from symbol 0 in slot 0, slot 4, slot 8, ..., and the repeating search space can be set from symbol 7 in the next slots, that is, slot 1, slot 5, slot 9, ....

[0375] A base station can set multiple search spaces within a CORESET configured for a single slot. To this end, the base station can indicate to the terminal the starting symbol number (K) of the search space. For example, if the K value is 2, there can be two search spaces configured for slot n. Specifically, the first search space can be set from the first symbol of slot n, and the second search space can be set from the symbol immediately following the last symbol of the first search space.

[0376] A base station can set multiple search spaces within a CORESET set in one slot. To this end, the base station can indicate to the terminal K indices of the starting symbols of the search spaces. For example, if the value of K is 2, the starting symbol indices indicated by the base station may be the first index and the second index, and there may be two search spaces. In this case, if the value of the first index is 0, the first search space may be set from the first symbol of slot n, and if the value of the second index is 2, the second search space may be set from the third symbol of slot n.

[0377] Method C described above, since the area where the PDCCH is transmitted is a single CORESET, the frequency-domain resources are fixed to a certain band, and the number of symbols in the CORESET is also fixed. In this specification, a single CORESET may refer to the same time-frequency domain resources set for each slot. Therefore, it is disadvantageous in terms of frequency diversity, and the number of symbols cannot be adjusted according to the slot configuration. A method to address these issues is described below.

[0378] iv) Method D

[0379] A base station can configure multiple CORESETs for a single downlink BWP. The time-frequency domain resources of each CORESET can be configured independently. Furthermore, each CORESET can have one or more search spaces configured. Specifically, each of the multiple search spaces can be mapped to each CORESET based on the CORESET-indicating branch.

[0380] For example, a different search space may be set for each of a plurality of CORESETs. The base station may transmit an indicator to the terminal indicating a PDCCH to be repeatedly transmitted on the plurality of CORESETs. Specifically, the base station may transmit an indicator to the terminal indicating that the PDCCH is repeatedly transmitted on the first CORESET and the second CORESET. At this time, if the value of the indicator is 1, this may indicate that the repeated PDCCH is transmitted on the first search space corresponding to the first CORESET, and if the value of the indicator is 2, this may indicate that the repeated PDCCH is transmitted on the second search space corresponding to the second CORESET. At this time, the DCIs included in the PDCCHs repeatedly transmitted on each of the plurality of CORESETs may be identical.

[0381] For example, a base station can configure multiple CORESETs and a search space. Specifically, a terminal can receive an indicator from the base station indicating to which of the multiple CORESETs a single search space is mapped. In addition, the terminal can receive (configure) a period, an offset, and an index of a start symbol of the search space from the base station. The search spaces determined based on the period, the offset, and the index of the start symbol can be sequentially mapped to the multiple CORESETs. In this case, the DCI included in each PDCCH transmitted on the multiple CORESETs can be the same. Since the DCI can be transmitted on the multiple CORESETs, frequency diversity can be obtained.

[0382] Figure 44 illustrates that a PDCCH is transmitted on a plurality of control resource sets according to one embodiment of the present invention.

[0383] Referring to FIG. 44, the search space period may be 2 slots, and the offset may be 0 slots. Accordingly, the search spaces may be set to slots 0, 2, 4, 6, 8, .... The search spaces set to slots 0, 2, 4, 6, 8, ... may each be mapped to one of two CORESETs (CORESET#A, CORSET#B). The odd-numbered search spaces (i.e., the search spaces set to slots 0, 4, and 8) may be mapped to CORESET#A, and the even-numbered search spaces (i.e., the search spaces set to slots 2 and 6) may be mapped to CORESET#B. In this case, the section of the resource in which the PDCCH is transmitted may be equal to the product of the search space period and the number of CORESETs. That is, the product of 2, which is the search space period, and 2, which is the number of CORESETs, can be 4, which is the resource section in which the PDCCH is transmitted, and the unit can be a slot. The terminal can receive the PDCCH in the sections of slot 0, slot 1, slot 2, and slot 3. In addition, the terminal can receive the PDCCH in the sections of slot 4, slot 5, slot 6, and slot 7.

[0384] A search space can be set based on a plurality of periods, offsets, and indices of start symbols set from a base station. Since the plurality of search spaces correspond to a plurality of CORESETs, the number of search spaces and the number of CORESETs can be the same. In other words, the number of sets of setting values ​​for each search space can be the same as the number of CORESETs. In this case, the set can include a plurality of periods, offsets, and indices of start symbols. For example, a search space determined based on the indices of a first period, offset, and start symbol can be mapped to a first CORESET, and a search space determined based on the indices of a second period, offset, and start symbol can be mapped to a second CORESET.

[0385] Additionally, the search space can be set based on the number of slots (K) in which the search space is repeated. In this case, K can be equal to the number of CORESETs, and thus K can be set without separate signaling. For example, if K is 2, slot n is determined based on the period and offset, and the search space determined based on the starting symbol index in slot n can be mapped to the first CORESET, and the search space determined based on the starting symbol index in slot n+1 can be mapped to the second CORESET.

[0386] Additionally, the search space may be determined based on the number of indexes of the starting symbol. In this case, the number of indexes of the starting symbol and the number of CORESETs may be the same. For example, if the number of indexes of the starting symbol is 2, the search space determined based on the first starting symbol index in slot n may be mapped to the first CORESET, and the search space determined based on the second starting symbol index in slot n+1 may be mapped to the second CORESET.

[0387] v) Method E

[0388] A method for receiving a DM-RS of a repetitive PDCCH containing the same DCI transmitted by a base station to a terminal is described.

[0389] A wideband reference signal (RS) can be set. The terminal can determine which REGs are assumed to have the same precoder based on whether a wideband RS is set.

[0390] If a wideband RS is not configured, the terminal can assume that the REGs comprising the REG bundle have the same precoder applied. That is, the terminal can perform channel estimation using the DM-RSs of the REGs included in the REG bundle. Based on the channel estimation results, the terminal can compensate for the phase of the signal received from the REs included in the REG bundle.

[0391] When a wideband RS is configured, the terminal may assume that the same precoder is applied to adjacent REGs in the time-frequency domain. The terminal may assume that the same precoder is applied to adjacent REGs in the time-frequency domain among REGs mapped to multiple CORESETs. In this case, the multiple CORESETs may be regions in which the same DCI is transmitted. In addition, the terminal may assume that the same precoder is applied to adjacent REGs in the time-frequency domain among REGs corresponding to multiple search spaces. In this case, a PDCCH including the same DCI may be transmitted in the search space. The terminal may assume that the same precoder is applied to adjacent REGs in the time-frequency domain among REGs included in one CORESET. In other words, the terminal does not assume that the same precoder is applied to REGs in different CORESETs even if they are adjacent in the time-frequency domain. Different CORESETs may include CORESETs in which the same DCI is repeatedly transmitted. Meanwhile, CORESETs in which the same DCI is repeatedly transmitted may be excluded from different CORESETs. The terminal may assume that the same precoder is applied to adjacent REGs in the time-frequency domain among REGs corresponding to a single search space. That is, even if adjacent REGs in the time-frequency domain are included in the same CORESET, if they correspond to different search spaces, the terminal does not assume that the same precoder is applied. Different search spaces may include search spaces in which the same DCI is transmitted. Meanwhile, search spaces in which the same DCI is transmitted may be excluded from different search spaces.

[0392] The terminal can assume that the same precoder is applied to REGs in an area where the PDCCH is repeatedly transmitted (such as multiple basic CORESETs constituting one CORESET, multiple search spaces corresponding to one CORESET, or multiple CORESETs). The areas where the PDCCH is repeatedly transmitted do not necessarily need to be adjacent in the time-frequency domain. That is, the terminal can assume that the same precoder is applied to REGs included in areas that are not adjacent in the time-frequency domain. As a result, the terminal can assume that the same precoder is applied to areas that are not adjacent in the time-frequency domain, and thus, there is an effect of improving channel estimation performance using DM-RS.

[0393] A base station may transmit a repetitive PDCCH containing the same DCI to a terminal, and some of the REs of the symbols among the resources used for transmission may not be used for DM-RS but may be used to transmit DCI. For example, if repetitive PDCCHs containing the same DCI are configured to be transmitted on adjacent symbols, the base station may not allocate DM-RS to the REs of all symbols for transmitting each repetitive PDCCH. In this case, all or some of the symbols to which DM-RSs are not assigned may be used to transmit DCI. Each repetitive PDCCH may be an adjacent PDCCH in the resource region. In this case, a specific method for allocating DM-RS is described below.

[0394] i) The base station may not include DM-RS in some or all of the REs corresponding to symbols in which the kth multiple of a PDCCH is transmitted among the repeated PDCCHs. For example, when k is 2, the base station may not allocate DM-RS to some or all of the symbols in which the PDCCH corresponding to the multiple of 2 (i.e., even-numbered) among the repeated PDCCHs is transmitted. ii) The base station may not allocate DM-RS to some or all of the REs corresponding to every kth multiple of a PDCCH symbol in which the DM-RS is repeatedly transmitted among the kth multiple of a symbol of each repeated PDCCH. For example, when k is 2, the base station may not allocate DM-RS to some or all of the REs corresponding to the multiple of 2 (i.e., even-numbered) symbols of each repeated PDCCH. iii) The base station may allocate DM-RS to the REs corresponding to the kth symbol of each repeated PDCCH, and may not allocate DM-RS to the REs corresponding to the remaining symbols except for the kth symbol. For example, if k is 1, DM-RSs may be allocated to REs corresponding to the first symbol of each repeated PDCCH, and DM-RSs may not be mapped to REs corresponding to symbols other than the first symbol. iv) The base station may allocate DM-RSs to REs corresponding to the first to k-th symbols of each repeated PDCCH, and may not allocate DM-RSs to all or some of the REs corresponding to symbols other than the first to k-th symbols. For example, if k is 2, the base station may allocate DM-RSs to REs corresponding to the first and second symbols of each repeated PDCCH, and may not allocate DM-RSs to all or some of the REs other than the REs corresponding to the first and second symbols. In the above iii) and iv), the value of k may be determined based on the number of symbols on which the PDCCH is transmitted.For example, k can be determined as ceil(PDCCH_length / 2). PDCCH_length is the number of symbols in which the PDCCH is transmitted. That is, if the number of symbols in which the PDCCH is transmitted is 1 or 2, k is 1, and if the number of symbols is 3, k is 2. In this case, the value of k can be a value set by the base station.

[0395] vi) Method F

[0396] DM-RSs assigned to repetitive PDCCHs containing the same DCI may use the same sequence. That is, the UE may assume that the DM-RSs assigned to repetitive PDCCHs use the same sequence, and thus determine that the DCIs included in the repetitive PDCCHs are identical. Furthermore, the UE may perform phase compensation by utilizing or comparing the DM-RSs assigned to the repetitive PDCCHs. The DCIs included in the repetitive PDCCHs may be identical.

[0397] Specifically, more specifically slot n μ s,f The sequence of DM-RS assigned to symbol l can be determined as in mathematical expression 2.

[0398]

[0399] In mathematical expression 2, the initial value of the pseudo-random sequence c(i) can be calculated as in mathematical expression 3.

[0400]

[0401] n in equation 3 μ s,f is the index of the slot within the subframe, l is the index of the symbol within the slot, and N ID can be one of the values ​​0,1,…,65535 or the same value as the cell ID.

[0402] Below, a method for applying the same sequence to DM-RS allocated to a repeated PDCCH is described.

[0403] i) The sequence used for the DM-RS allocated to the repetitive PDCCH may have the same initial value. The initial value may be determined using the index of the slot and the symbol index in which the first PDCCH among the repetitive PDCCHs is transmitted. The determined initial value may be used for each symbol of each slot in which the repetitive PDCCHs are transmitted. For example, the first PDCCH among the repetitive PDCCHs may be transmitted in symbols i and i+1 of slot n1, and the second PDCCH among the repetitive PDCCHs may be transmitted in symbols j and j+1 of slot n2. In this case, the initial value of the DM-RS sequence of the second PDCCH may be used as the initial value of the DM-RS sequence of the first PDCCH. That is, the initial value of the sequence used for the DM-RS allocated to the first symbol of the second PDCCH is c init (n1, i), and the initial value of the sequence used for the DM-RS allocated to the second symbol of the second PDCCH is c init(n1, i+1). ii) When a repetitive PDCCH is transmitted on one slot, the index values ​​l of the symbols of the resource region transmitting the repetitive PDCCH may all be set to the same value. For example, when a repetitive PDCCH is repeated four times on one slot, specifically, the first repetitive PDCCH may be transmitted on symbols 0 to 2, the second repetitive PDCCH on symbols 3 to 5, the third repetitive PDCCH on symbols 6 to 8, and the fourth repetitive PDCCH on symbols 9 to 11. At this time, the index value l of the first symbol (i.e., symbols 0, 3, 6, 9) in the region transmitting each repetitive PDCCH may be set to 0, and the index value l of the second symbol (i.e., symbols 1, 4, 7, 11) may be set to 1. As another example, the index value of the symbol on which the first PDCCH among the repetitive PDCCHs is transmitted may be set to the value l. That is, the index value of the symbol on which the remaining PDCCHs except the first PDCCH among the repeated PDCCHs are transmitted can be l. iii) If the repeated PDCCHs are transmitted on different slots, the index value of the slot is n from the initial value of the DM-RS. μ s,f can all be the same value. For example, n of the first slot in which the PDCCH is transmitted repeatedly μ s,f can be set to 0, and n in the second slot μ s,f can be set to 1. As another example, n μ s,f may be the index of the slot in which the first PDCCH among the repeated PDCCHs is transmitted. That is, n of the remaining PDCCHs except the first μ s,f may be equal to the index of the slot in which the first PDCCH is transmitted.

[0404] iv) n μ s,fcan be applied equally to N slots. For example, n μ s,f is c init (floor( n μ s,f / N)*N, l) can be determined. floor(x) is a function that returns the largest integer among integers less than or equal to x. N can be a value set by the base station. N can be a value determined based on the number of slots in which the repetitive PDCCH is transmitted. N can be the same as the number of slots in which the repetitive PDCCH is transmitted. v) n μ s,f can be used identically for N slots based on a specific slot (e.g., slot n0). For example, n μ s,f is c init (floor((n μ s,f - n0) / N)*N, l). N may be a value set by the base station. N may be a value determined based on the number of slots in which the repetitive PDCCH is transmitted. N may be the same as the number of slots in which the repetitive PDCCH is transmitted. n0 may be the index of the slot in which the first PDCCH of the repetitive PDCCH is transmitted. n0 may be set by the base station.

[0405] The CCEs corresponding to the PDCCH candidates of the first search space of the first CORSET, where repetitive PDCCHs including the same DCI are transmitted, and the PDCCH candidates of the second search space of the second CORESET may be determined based on a hashing function. The number of blind decoding operations and the number of non-overlapping CCEs for monitoring repetitive PDCCH candidates and receiving repetitive PDCCHs in the first search space may be different from the number of blind decoding operations and the number of non-overlapping CCEs for monitoring repetitive PDCCHs and receiving repetitive PDCCHs in the second search space. That is, the maximum number of blind decoding operations and the number of non-overlapping CCEs per slot (or during a specific time interval) may be different from each other. Accordingly, the terminal may receive repetitive PDCCHs in the first search space (i.e., when the conditions for the maximum number of blind decoding operations and the number of non-overlapping CCEs are satisfied), but may not receive repetitive PDCCHs in the second search space. Therefore, it is difficult to expand coverage by repeatedly receiving PDCCHs. Below, a method of applying a hashing function to expand coverage is described.

[0406] vii) Method G

[0407] The same hashing function can be applied to an area where repeated PDCCHs containing the same DCI are repeatedly transmitted (multiple basic CORESETs constituting one CORESET, multiple search spaces corresponding to one CORESET, or multiple CORESETs, etc.).

[0408] Specifically, slot n included in the search space s of CORESET p μ s,f PDCCH candidate The CCEs that constitute the PDCCH can be determined by a hashing function such as mathematical expression 4. At this time, the aggregation level of the PDCCH candidate can be L.

[0409]

[0410] If the search space s is a common search space, can be 0. If the search space s is a terminal-specific search space, Is And, is n RNTI is equal to and is not 0. In addition, can be 39827 when p mod 3 is 0, 39829 when p mod 3 is 1, and 39839 when p mod 3 is 2. D can be 65537. n RNTI can be a C-RNTI value.

[0411] If up to 5 CORESETs can be set for repeated PDCCH transmission, p can have a value of 0 to 4. If the search space s is a terminal-specific search space, Is And, is n RNTI is equal to and is not 0. In addition, A p can be 39827 when p mod 5 is 0, 39829 when p mod 5 is 1, 39839 when p mod 5 is 2, 39841 when p mod 5 is 3, and 39847 when p mod 5 is 4. D can be 65537.

[0412] N CCE,p M can be the number of CCEs that make up the CORESET. (L) s,max may be the number of repetitive PDCCH candidates whose aggregation level is L monitored by the terminal. n CI may be a value indicated by the carrier indicator field.

[0413] If the search space s is a common search space, can be 0 regardless of the slot. Therefore, N CCE,p If the CCEs are identical, the hashing function outputs the same value. Therefore, the CORESET corresponding to the search space where the repeated PDCCH is transmitted can be composed of the same number of CCEs. On the other hand, if the CORESET does not consist of the same number of CCEs, the terminal must calculate the hashing function by assuming a specific number of CCEs.

[0414] Hereinafter, a method for determining a specific number will be described. If the number of CCEs constituting multiple CORESETs is different, the specific number may be determined based on the CORESET consisting of the fewest CCEs. Alternatively, the specific number may be determined based on the CORESET consisting of the most CCEs. Alternatively, the specific number may be determined based on the CORESET in which the first PDCCH among the repeated PDCCHs is transmitted. Alternatively, the specific number may be determined based on the CORESET with the lowest index among the multiple CORESETs. Alternatively, the specific number may be determined based on the CORESET with the highest index among the multiple CORESETs.

[0415] If the search space s is a terminal-specific search space, can be determined differently for each slot. Therefore, in order for the hashing function to output the same value, can be fixed to a specific value. Below Describes how to determine i) is the slot index n μ s,f can be determined to a specific value regardless of the . For example, The search space s can be determined to a specific value different from the value used when it is a common search space (i.e., 0). Silver N CCE,p It may be a specific value determined based on. Specifically, Silver N CCE,p can be determined based on half of the total. For example, is floor(N CCE,p / 2), ceil(N CCE,p / 2), round(N CCE,p / 2) can be determined based on. round(x) is a function that returns the rounded value of x. N CCE,p Based on half of When determining, half of the resources constituting the CORESET can be used as a common search space, and the other half can be used as a terminal-specific search space. ii) has a specific value for a certain time unit and can be changed at certain time units. The certain time unit can be a slot unit and can be set by the base station. Also, the certain time unit can be the same as the number of times the PDCCH is repeatedly transmitted. For example, during N slots (a certain time unit) can have a specific value. Specifically, n μ s,f If the remainder of dividing by N is not 0, Is is the same as n μ s,f If the remainder of dividing by N is 0, then Is It can be. Another example is that during N slots is determined by a fixed specific value, and by the offset M. can be updated. M can be a value from 0 to N-1. n μ s,f If the remainder when divided by N is not M, Is is the same as n μ s,f If the remainder when divided by N is M, Is M may be a value set by the base station. As another example, the offset M may be determined based on the index S of the slot in which the first PDCCH among the repeated PDCCHs is transmitted. Specifically, M may be determined as S mod N. can be the same value during the slots in which the repeated PDCCHs are transmitted. iii) If the repeated PDCCHs are transmitted on different CORESETs, there are multiple values ​​of p, which is the CORESET index. can be determined differently depending on the p value. Therefore, the p value can be fixed to a specific value. For example, the p value can be fixed to 0. As another example, the p value can be determined based on the index of the CORESET in which the first PDCCH among the repeated PDCCHs is transmitted. As another example, the p value can be determined based on the lowest index or the highest index among the indices of the configured CORESETs.

[0416] Figure 45 is a flowchart showing the transmission of a repetitive PDCCH according to an embodiment of the present invention.

[0417] Referring to FIG. 45, a method for transmitting a repetitive PDCCH including the same DCI described above through FIGS. 1 to 44 is described.

[0418] The terminal can receive configuration information for the first CORESET from the base station and configuration information for the second CORESET (S4510, S4520).

[0419] The terminal can receive a first PDCCH transmitted from the base station on the first CORESET and a second PDCCH transmitted on the second CORESET (S4530, S4540).

[0420] At this time, the first PDCCH and the second PDCCH may be repeatedly transmitted from the base station, respectively.

[0421] The first DCI included in the first PDCCH and the second DCI included in the second PDCCH may be identical to each other.

[0422] The first PDCCH and the second PDCCH may be set to the same aggregation level (AL).

[0423] The first CORESET and the second CORESET may be resources in different time-frequency domains, and the first CORESET and the second CORESET may be resources in the same time-frequency domain.

[0424] The first PDCCH and the second PDCCH may be included in the same slot and transmitted repeatedly, and the first PDCCH and the second PDCCH may be transmitted repeatedly on different slots.

[0425] The first DCI and the second DCI can be independently decoded, and the first DCI and the second DCI can be combined and decoded. In this case, if the terminal cannot independently decode the first DCI and the second DCI, the terminal can combine and decode the first DCI and the second DCI.

[0426] The terminal may receive configuration information for a first search space and configuration information for a second search space from the base station. The first search space may be associated with the first CORESET, and the second search space may be associated with the second CORESET. In this case, the first search space and the second search space may be resources in different time domains. In addition, the first PDCCH may be received on the first search space, and the second PDCCH may be received on the second search space.

[0427] The configuration information for the first search space may include information about the period of the first search space, and the configuration information for the second search space may include information about the period of the second search space. In this case, the period of the first search space and the period of the second search space may be the same.

[0428] The terminal may transmit HARQ-ACK information for either the first PDCCH or the second PDCCH to the base station. At this time, the HARQ-ACK information may be HARQ-ACK information for a PDCCH transmitted on a search space having a lower index among the indexes of the first search space and the indexes of the second search space.

[0429] The terminal may receive a third PDCCH from the base station on a third search space. The terminal may transmit HARQ-ACK information for any one of the first PDCCH, the second PDCCH, and the third PDCCH to the base station. At this time, the third PDCCH may include a third DCI different from the first DCI and the second DCI. When the third search space overlaps with any one of the first search space or the second search space, the HARQ-ACK information may be HARQ-ACK information for a PDCCH transmitted on a search space having a lowest index among the indices of the overlapping search spaces.

[0430] The type of the first search space and the type of the second search space may be the same. In this case, the type of the first search space and the type of the second search space may be either a common search space or a UE-specific search space.

[0431] The terminal performing the method described in FIG. 45 may be the terminal described in FIG. 11. Specifically, the terminal may be configured to include a communication module for transmitting and receiving wireless signals and a processor for controlling the communication module. In this case, the processor of the terminal may perform the method for receiving a repetitive PDCCH described herein.

[0432] Additionally, the base station transmitting the repetitive PDCCH described herein may be configured to include a communication module for transmitting and receiving wireless signals, and a processor for controlling the communication module. In this case, the base station may be the base station described in FIG. 11. In this case, the processor of the base station may perform the method for transmitting the repetitive PDCCH described herein.

[0433] Although the methods and systems of the present invention have been described with respect to specific embodiments, some or all of their components or operations may be implemented using a computing system having a general-purpose hardware architecture.

[0434] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0435] The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. In a method for receiving a physical downlink control channel (PDCCH) in a wireless communication system, a method performed by a terminal is as follows: A step of receiving configuration information for a first control resource set (CORESET) from a base station; A step of receiving configuration information for a second CORESET from the base station; A step of receiving a first PDCCH transmitted on the first CORESET from the base station; and A step of receiving a second PDCCH transmitted on the second CORESET from the base station, The above first PDCCH and the above second PDCCH are each repeatedly transmitted from the base station, A method characterized in that the first downlink control information (DCI) included in the first PDCCH and the second DCI included in the second PDCCH are identical to each other.

2. In paragraph 1, A method characterized in that the first PDCCH and the second PDCCH are set to the same aggregation level (AL).

3. In paragraph 1, A method characterized in that the first CORESET and the second CORESET are resources in different time-frequency domains.

4. In paragraph 1, A method characterized in that the first CORESET and the second CORESET are resources in the same time-frequency domain.

5. In paragraph 1, A method characterized in that the first PDCCH and the second PDCCH are included in the same slot and transmitted repeatedly.

6. In paragraph 1, A method characterized in that the first PDCCH and the second PDCCH are repeatedly transmitted on different slots.

7. In paragraph 1, A method characterized in that the first DCI and the second DCI are each independently decoded.

8. In paragraph 1, A method characterized in that the first DCI and the second DCI are combined and decoded.

9. In paragraph 1, A step of receiving configuration information for a first search space from the base station; and Further comprising a step of receiving configuration information for a second search space from the base station, The first search space is associated with the first CORESET, and the second search space is associated with the second CORESET. The above first search space and the above second search space are resources in different time domains, A method characterized in that the first PDCCH is received on the first search space and the second PDCCH is received on the second search space.

10. In paragraph 9, The configuration information for the first search space includes information about the period of the first search space, The configuration information for the second search space includes information about the period of the second search space, A method characterized in that the period of the first search space and the period of the second search space are the same.

11. In paragraph 9, Further comprising a step of transmitting HARQ-ACK information for one of the first PDCCH and the second PDCCH to the base station, A method characterized in that the above HARQ-ACK information is HARQ-ACK information for a PDCCH transmitted on a search space having a lower index among the indexes of the first search space and the indexes of the second search space.

12. In paragraph 9, A step of receiving a third PDCCH in a third search space from the above base station; Further comprising a step of transmitting HARQ-ACK information for any one of the first PDCCH, the second PDCCH and the third PDCCH to the base station, The third PDCCH includes a third DCI different from the first DCI and the second DCI, If the third search space overlaps with either the first search space or the second search space, A method characterized in that the above HARQ-ACK information is HARQ-ACK information for a PDCCH transmitted on a search space having the lowest index among the indices of overlapping search spaces.

13. In paragraph 9, The type of the first search space and the type of the second search space are identical to each other, A method characterized in that the type of the first search space and the type of the second search space are either a common search space or a UE specific search space.

14. In a terminal receiving a physical downlink control channel (PDCCH) in a wireless communication system, the terminal, Transmitter and receiver; comprising a processor controlling the transceiver; The above processor, Receive configuration information for a first control resource set (CORESET) from a base station, From the above base station, configuration information for the second CORESET is received, From the above base station, a first PDCCH transmitted on the first CORESET is received, From the above base station, a second PDCCH transmitted on the second CORESET is received, The above first PDCCH and the above second PDCCH are each repeatedly transmitted from the base station, A terminal, characterized in that the first downlink control information (DCI) included in the first PDCCH and the second DCI included in the second PDCCH are identical to each other.

15. In paragraph 14, A terminal, characterized in that the first PDCCH and the second PDCCH are set to the same aggregation level (AL).

16. In paragraph 14, A terminal characterized in that the first PDCCH and the second PDCCH are included in the same slot and transmitted repeatedly.

17. In paragraph 14, A terminal characterized in that the first PDCCH and the second PDCCH are repeatedly transmitted on different slots.

18. In paragraph 14, The above processor, From the above base station, configuration information for the first search space is received, Further comprising a step of receiving configuration information for a second search space from the base station, The first search space is associated with the first CORESET, and the second search space is associated with the second CORESET. The above first search space and the above second search space are resources in different time domains, A terminal, characterized in that the first PDCCH is received on the first search space, and the second PDCCH is received on the second search space.

19. In paragraph 18, The configuration information for the first search space includes information about the period of the first search space, The configuration information for the second search space includes information about the period of the second search space, A terminal characterized in that the period of the first search space and the period of the second search space are the same.

20. In a method for transmitting a physical downlink control channel (PDCCH) in a wireless communication system, the method performed by a base station comprises: A step of transmitting configuration information for a first control resource set (CORESET) to a terminal; A step of transmitting configuration information for a second CORESET to the above terminal; A step of transmitting a first PDCCH on the first CORESET to the terminal; and Including a step of transmitting a second PDCCH on the second CORESET to the above terminal, The above first PDCCH and the above second PDCCH are repeatedly transmitted to the terminal, respectively, A method characterized in that the first downlink control information (DCI) included in the first PDCCH and the second DCI included in the second PDCCH are identical to each other.

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