Method and apparatus for transmitting a physical downlink control channel in a wireless communication system.

Abstract

To provide a method and an apparatus for transmitting a physical downlink channel in a wireless communication system.SOLUTION: A method for receiving a physical downlink control channel (PDCCH) in a wireless communication system includes the steps of receiving configuration information regarding a first control resource set (CORESET) from a base station, receiving configuration information regarding a second CORESET from the base station, receiving a first PDCCH transmitted on the first CORESET from the base station, and receiving a second PDCCH transmitted on the second CORESET from the base station by a terminal.SELECTED DRAWING: Figure 45

Description

[Technical Field]

[0001] This specification relates to a wireless communication system, specifically to a method and apparatus for transmitting a physical downlink control channel. [Background technology]

[0002] Following the commercialization of fourth-generation (4G) communication systems, efforts are underway to develop a new fifth-generation (5G) communication system to meet the growing demand for wireless data traffic. 5G communication systems are also referred to as post-LTE systems or new radio (NR) systems, or the next generation of network communication systems beyond 4G. To achieve high data transfer rates, 5G communication systems include systems operating using millimeter-wave (mmWave) bands above 6 GHz, as well as systems operating using frequency bands below 6 GHz to ensure coverage. Consequently, implementation forms at base stations and terminals are still under consideration.

[0003] This increases efficiency and enables communication providers to deliver more data and voice services over a given bandwidth. Therefore, 3GPP NR systems are designed to meet the demand for high-speed data and media transmission, in addition to supporting large volumes of voice. The advantages of NR systems include higher throughput and lower latency on the same platform, support for frequency division duplexing (FDD) and time division duplexing (TDD), and lower operating costs with an extended end-user environment and a simpler architecture. For more efficient data processing, dynamic TDD in NR systems can use methods to vary the number of orthogonal frequency division multiplexing (OFDM) symbols that can be used in uplink and downlink, according to the data traffic direction of the cell user. For example, when a cell's downlink traffic is greater than its uplink traffic, the base station may allocate more downlink OFDM symbols to slots (or subframes). Information about the slot configuration should be transmitted to the terminal.

[0004] To mitigate path loss in the ultra-high frequency band and increase the transmission distance of radio waves, beamforming, massive multi-input multi-output (MIMO), full-dimensional multi-input multi-output (FD-MIMO), array antennas, analog beamforming, hybrid beamforming (combining analog and digital beamforming), and large-scale antenna technologies are being discussed for 5G communication systems. Furthermore, in order to improve the system network, 5G communication systems are undergoing technological development related to 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, CoMP (coordinated multi-points), and interference cancellation.In addition, 5G systems have seen the development of advanced coding modulation (ACM) methods such as FQAM (hybrid FSK and QAM modulation) and SWSC (sliding window superposition coding), as well as advanced access technologies such as FBMC (filter bank multi-carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access).

[0005] On the other hand, in a human-centered connected network where humans generate and consume information, the internet is evolving into the Internet of Things (IoT) network, where information is exchanged between distributed components such as objects. Internet of Everything (IoE) technology is also emerging, combining IoT technology with big data processing technology through connectivity to cloud servers. Implementing IoT requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology. As a result, in recent years, technologies such as sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) have been explored for object-to-object connectivity. In an IoT environment, intelligent internet technology (IT) services can be provided that collect and analyze data generated from connected objects to create new value in human life. Through the integration and blending of existing information technology (IT) with various industries, IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0006] Therefore, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) are implemented using techniques such as beamforming, MIMO, and array antennas. The application of cloud RAN as a big data processing technology described above is an example of the convergence of 5G technology and IoT technology. In general, mobile communication systems are 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 developed to the point where high-speed data services are available. However, due to resource shortages in currently available mobile communication systems and the demand for high-speed services from users, more advanced mobile communication systems are needed. [Overview of the project] [Problems that the invention aims to solve]

[0008] This specification aims to provide a method and apparatus for transmitting a physical downlink channel in a wireless communication system. [Means for solving the problem]

[0009] This 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, performed by a terminal, includes the steps of: receiving configuration information relating to a first control resource set (CORESET) from a base station; receiving configuration information relating to a second CORESET from the base station; receiving a first PDCCH transmitted on the first CORESET from the base station; and receiving a second PDCCH transmitted on the second CORESET from the base station, wherein the first PDCCH and the second PDCCH are transmitted repeatedly from the base station, and the first Downlink Control Information (DCI) contained in the first PDCCH and the second DCI contained in the second PDCCH are identical.

[0011] Furthermore, in this specification, the method performed by the terminal further includes the steps of receiving configuration information relating to a first search space from the base station; and receiving configuration information relating to 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, the first PDCCH is received in the first search space, and the second PDCCH is received in the second search space.

[0012] Furthermore, in this specification, the method performed by the terminal further includes the step of transmitting HARQ-ACK information to the base station for either the first PDCCH or the second PDCCH, wherein the HARQ-ACK information is HARQ-ACK information for a PDCCH transmitted in the search space of the lower index of the index of the first search space and the index of the second search space.

[0013] Furthermore, in this specification, the method performed by the terminal further includes the steps of: receiving a third PDCCH from the base station in a third search space; and transmitting HARQ_ACK information to the base station 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 either the first or the second search space, the HARQ-ACK information is HARQ-ACK information for a PDCCH transmitted in the search space with the lowest index among the indices of the overlapping search spaces.

[0014] Furthermore, in this specification, a terminal that receives a Physical Downlink Control Channel (PDCCH) in a wireless communication system includes a transceiver and a processor that controls the transceiver, the processor being configured to receive configuration information relating to a first control resource set (CORESET) from a base station, configuration information relating to a second CORESET from the base station, a first PDCCH transmitted on the first CORESET from the base station, and a second PDCCH transmitted on the second CORESET from the base station, the first PDCCH and the second PDCCH being transmitted repeatedly from the base station, and the first Downlink Control Information (DCI) contained in the first PDCCH and the second DCI contained in the second PDCCH being the same.

[0015] Furthermore, in this specification, the processor is further configured to receive configuration information relating to a first search space from the base station and configuration information relating to a second search space from the base station, 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, the first PDCCH is received in the first search space and the second PDCCH is received in the second search space.

[0016] Furthermore, in this specification, the first PDCCH and the second PDCCH are set to the same Aggregation Level (AL).

[0017] Furthermore, in this specification, the first CORESET and the second CORESET are resources in different time-frequency domains.

[0018] Furthermore, in this specification, the first CORESET and the second CORESET are resources in the same time-frequency domain.

[0019] Furthermore, in this specification, the first PDCCH and the second PDCCH are included in the same slot and transmitted repeatedly.

[0020] Furthermore, in this specification, the first PDCCH and the second PDCCH are transmitted repeatedly on different slots.

[0021] Furthermore, in this specification, the first DCI and the second DCI are decoded independently.

[0022] Furthermore, in this specification, the first DCI and the second DCI are decoded by concatenating them with each other.

[0023] Furthermore, in this specification, the configuration information relating to the first search space includes information relating to the period of the first search space, and the configuration information relating to the second search space includes information relating to the period of the second search space, and the period of the first search space and the period of the second search space are the same.

[0024] Furthermore, in this 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 either a Common Search Space or a UE-specific Search Space.

[0025] Furthermore, in this specification, a method for transmitting a Physical Downlink Control Channel (PDCCH) in a wireless communication system, performed by a base station, includes the steps of: transmitting configuration information relating to a first control resource set (CORESET) to a terminal; transmitting configuration information relating to 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, and the first Downlink Control Information (DCI) contained in the first PDCCH and the second DCI contained in the second PDCCH are identical. [Effects of the Invention]

[0026] This specification aims to improve PDCCH reception reliability by having a terminal receive the same DCI on multiple PDCCHs.

[0027] One embodiment of the present invention provides a method for efficiently transmitting and receiving physical channels and signals in a wireless communication system, and an apparatus utilizing the same. The effects obtained from the present invention are not limited to those mentioned above, and other effects not mentioned should be clearly understood by those with ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawing]

[0028] [Figure 1] This figure shows an example of a wireless frame structure used in a wireless communication system. [Figure 2] This figure shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. [Figure 3] This diagram illustrates the physical channels used in 3GPP systems and typical signal transmission methods that utilize these physical channels. [Figure 4a] This figure shows the SS / PBCH block for initial cell access in a 3GPP NR system. [Figure 4b] This figure shows the SS / PBCH block for initial cell access in a 3GPP NR system. [Figure 5a] This diagram shows the procedure for transmitting control information and control channels in a 3GPP NR system. [Figure 5b] This diagram shows the procedure for transmitting control information and control channels in a 3GPP NR system. [Figure 6] This diagram shows the control resource set (CORESET) that can be transmitted within a physical downlink control channel (PDCCH) in a 3GPP NR system. [Figure 7] This figure shows a method for constructing the PDCCH search space in the 3GPP NR system. [Figure 8]This is a conceptual diagram illustrating carrier aggregation. [Figure 9] This diagram illustrates single-carrier and multi-carrier communication. [Figure 10] This figure shows an example of how cross-carrier scheduling techniques are applied. [Figure 11] This is a block diagram showing the configuration of a terminal and a base station according to one embodiment of the present invention. [Figure 12] This figure shows scheduling of a physical downlink shared channel according to one embodiment of the present invention. [Figure 13] This figure shows the scheduling of a physical uplink control channel according to one embodiment of the present invention. [Figure 14] This figure shows scheduling of a physical uplink sharing channel and a physical uplink control channel according to one embodiment of the present invention. [Figure 15] This figure shows a representation of one embodiment of the present invention in which PDCCH is repeatedly transmitted across different sets of control resources. [Figure 16] This figure shows a representation of one embodiment of the present invention in which PDCCH is repeatedly transmitted in different search spaces. [Figure 17] This figure shows an embodiment of the present invention in which different repeating PDCCHs overlap in the time-frequency domain. [Figure 18] This figure shows a problem that occurs when a physical downlink shared channel determines the scheduled slot according to one embodiment of the present invention. [Figure 19] This figure shows a problem that occurs when a physical uplink sharing channel and a physical uplink control channel determine the scheduled slot according to one embodiment of the present invention. [Figure 20] This figure shows that a slot is determined by a dynamic slot format indicator according to one embodiment of the present invention. [Figure 21] This figure shows a problem that occurs when a slot is determined by a dynamic slot formatting directive according to one embodiment of the present invention. [Figure 22] This figure shows that a slot is determined based on a downlink preemption indicator according to one embodiment of the present invention. [Figure 23] This figure shows a problem that occurs when a slot is determined by a downlink preemption indicator according to one embodiment of the present invention. [Figure 24] This figure shows a slot determined by an uplink cancellation indicator according to one embodiment of the present invention. [Figure 25] This diagram illustrates the problems that occur when determining a slot using an uplink cancellation indicator. [Figure 26] This figure shows a method for determining a reference slot according to one embodiment of the present invention. [Figure 27] This figure shows a method for determining a reference slot according to one embodiment of the present invention. [Figure 28] This figure shows an active PDCCH and repeated PDCCH receiver according to one embodiment of the present invention. [Figure 29] This figure shows the configuration of a control resource set according to one embodiment of the present invention. [Figure 30] This figure shows the configuration of a control resource set according to one embodiment of the present invention. [Figure 31] This figure shows a control resource set composed of a basic control resource set according to one embodiment of the present invention. [Figure 32] This figure shows a control resource set composed of a basic control resource set according to one embodiment of the present invention. [Figure 33] This figure shows a method for designing a control resource set using a basic control resource set according to one embodiment of the present invention. [Figure 34] This figure shows a method for configuring a control resource set using a basic control resource set according to one embodiment of the present invention. [Figure 35] This figure shows a method for indexing CCE using a frequency-priority method according to one embodiment of the present invention. [Figure 36]This figure shows a method for indexing CCE using a time-priority method according to one embodiment of the present invention. [Figure 37] This figure shows a PDCCH candidate based on a frequency-priority indexed CCE according to one embodiment of the present invention. [Figure 38] This figure shows a PDCCH candidate based on a time-priority indexed CCE according to one embodiment of the present invention. [Figure 39] This figure shows that PDCCH is repeatedly received on the basic control resource set according to one embodiment of the present invention. [Figure 40] This figure shows an embodiment of the present invention in which a terminal applies interleaving to a basic control resource set to repeatedly receive PDCCH candidates. [Figure 41] This figure shows that PDCCH is repeatedly transmitted across multiple search spaces according to one embodiment of the present invention. [Figure 42] This figure shows that a PDCCH based on a search space and iteration setting is transmitted according to one embodiment of the present invention. [Figure 43] This figure shows that, according to one embodiment of the present invention, PDCCH is transmitted by different starting symbol positions based on the search space and iteration settings. [Figure 44] This figure shows a PDCCH being transmitted to a set of multiple control resources according to one embodiment of the present invention. [Figure 45] This flowchart shows that a repeating PDCCH is transmitted according to an embodiment of the present invention. [Modes for carrying out the invention]

[0029] The terminology used herein adopts common terms that are currently widely used as possible by considering the function of the present invention, but these terms may be modified in accordance with the intent, practice, and emergence of new technologies of those skilled in the art. Furthermore, in certain cases, there are terms that are at the discretion of the applicant, in which case their meanings will be explained in the corresponding descriptive sections of the present invention. It is therefore intended to be clear that the terminology used herein should be analyzed not only on the basis of the names of the terms but also on the substantive meaning of the terms and content throughout this specification.

[0030] Throughout this specification and the following claims, when an element is described as being “connected” to another element, that element may be “directly connected” to the other element, or “electrically connected” to the other element through a third element. Furthermore, unless explicitly stated otherwise, the word “equips” shall be understood as implying the inclusion of the element being described, and not as implying the exclusion of any other element, unless otherwise specified. Moreover, limitations such as “greater than” or “less than” based on a particular threshold may be appropriately replaced in some exemplary embodiments with “greater than” or “less than,” respectively.

[0031] The following technologies can be used in various wireless access systems, including Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), and Single Carrier FDMA (SC-FDMA). CDMA can be implemented by wireless technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented by wireless technologies such as Global System for Mobile Communications (GSM®) / General-Purpose Packet Radio Service (GPRS) / GSM® Advanced High-Speed ​​Data Rate (EDGE). OFDMA can be implemented by wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Advanced UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). The Third Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is part of Advanced UMTS (EUMTS), which uses Advanced UMTS Terrestrial Radio Access (E-UTRA), and LTE Advanced (A) is an advanced version of 3GPP LTE. 3GPP New Radio (NR) is a system designed separately from LTE / LTE-A to support the requirements of IMT-2020: enhanced mobile broadband (eMBB), ultra-reliable and low latency communication (URLLC), and massive machine type communication (mMTC) services. For clarity, 3GPP NR will be described primarily, but the technical ideas of this invention are not limited to them.

[0032] Unless otherwise specified in this specification, a base station may refer to a next-generation node B (gNB) as defined in 3GPP NR. Further, unless otherwise specified, a terminal may refer to a user equipment (UE). Hereinafter, for the sake of helping the understanding of the description, each content will be separately described as an example, but each example may be used in combination with each other. In the present disclosure, the configuration of a terminal can represent the configuration by a base station. Specifically, the base station can transmit a channel or a signal to the terminal and set the value of an operation of the terminal or a parameter used in a wireless communication system.

[0033] FIG. 1 shows an example of a wireless frame structure used in a wireless communication system.

[0034] Referring to FIG. 1, a wireless frame (or radio frame) used in a 3GPP NR system may have a length of 10 ms (Δf max N f / 100)*T c ). In addition, the wireless frame includes 10 subframes (SF: subframe) of equal size. In this specification, Δf max = 480*10 3 Hz, N f = 4096, T c = 1 / (Δf ref *N f,ref ), Δf ref = 15*10 3 Hz, and N f,ref = 2048. Numbers from 0 to 9 may be respectively assigned to the 10 subframes within one wireless frame. Each subframe has a length of 1 ms and may include one or more slots according to a subcarrier spacing. More specifically, in a 3GPP NR system, the subcarrier spacing that can be used is 15*2 μThe frequency is kHz, and μ can have values ​​of μ = 0, 1, 2, 3, 4 as the subcarrier spacing configuration. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz can be used for the subcarrier spacing. One subframe with a length of 1 ms is 2 μ It may contain 2 slots. In this case, the length of each slot is 2 -μ It is ms. 2 within one subframe μ Each slot has 0 to 2 μ Numbers up to -1 may be assigned. In addition, each slot within a single wireless frame can be assigned from 0 to 10*2. μ A number up to -1 may be assigned. Time resources can be distinguished by at least one of the following: wireless frame number (also called wireless frame index), subframe number (also called subframe index), and slot number (or slot index).

[0035] Figure 2 shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system. In particular, Figure 2 shows the resource grid structure of a 3GPP NR system.

[0036] Specifically, Figure 2 shows the structure of the resource grid in a 3GPP NR system. There is one resource grid per antenna port. Referring to Figure 2, a slot contains multiple orthogonal frequency division multiplexing (OFDM) symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. An OFDM symbol also means one symbol section. Unless otherwise specified, an OFDM symbol is sometimes simply called a symbol. One RB contains 12 consecutive subcarriers in the frequency domain. Referring to Figure 2, the signal transmitted from each slot is N size,μ grid,x *N RB sc Book subcarriers and N slot symbIt may be represented by a resource grid containing n OFDM symbols, where x=DL when the signal is a DL signal and x=UL when the signal is a UL signal. size,μ grid,x This represents the number of resource blocks (RBs) according to the subcarrier interval, which is a component of μ (where x is DL or UL), and N slot symb This represents the number of OFDM symbols in the slot. RB sc N is the number of subcarriers that make up one RB. RB sc = 12. OFDM symbols are sometimes called cyclic shift OFDM (CP-OFDM) symbols or discrete Fourier transform spread OFDM (DFT-s-OFDM) symbols, depending on the multiple access scheme.

[0037] The number of OFDM symbols contained in a single slot may vary depending on the length of the cyclic prefix (CP). For example, with a normal CP, a single slot may contain 14 OFDM symbols, while with an extended CP, a single slot may contain 12 OFDM symbols. In certain embodiments, the extended CP may be used only at a 60 kHz subcarrier interval. In Figure 2, for illustrative purposes, a single slot is configured using 14 OFDM symbols as an example, but embodiments of this disclosure may similarly apply to slots with different numbers of OFDM symbols. Referring to Figure 2, each OFDM symbol has N in the frequency domain. size,μ grid,x *N RB sc This includes subcarriers. Subcarrier types 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).

[0038] One RB is N in the frequency domain. RB sc (For example, 12) can be defined by consecutive subcarriers. For reference, a resource composed of one OFDM symbol and one subcarrier is sometimes called a resource element (RE) or tone. Thus, one RB is N slot symb *N RB sc It can be composed of individual resource elements. Each resource element in the resource grid can be uniquely defined by a pair of indices (k,l) within a single slot, where k ranges from 0 to N in the frequency domain. size,μ grid,x *N RB sc The index can be assigned up to -1, and l is from 0 to N in the time domain. slot symb It can be an index that can be assigned up to -1.

[0039] For a UE to receive signals from or transmit signals to a base station, the UE's time / frequency may be synchronized with the base station's time / frequency. This is because, when the base station and UE are synchronized, the UE can determine the time and frequency parameters necessary to demodulate the DL signal and transmit the UL signal at the appropriate time.

[0040] Each symbol in a radio frame used in time-division duplexing (TDD), i.e., in an unpaired spectrum, may consist of at least one of DL symbols, UL symbols, and flexible symbols. A radio frame used as a DL carrier in frequency-division duplexing (FDD), i.e., in a paired spectrum, may consist of DL symbols or flexible symbols, and a radio frame used as a UL carrier may consist of UL symbols or flexible symbols. DL symbols allow for DL ​​transmission but not UL transmission. UL symbols allow for UL transmission but not DL transmission. Flexible symbols may be determined to be used as DL or UL depending on the signal.

[0041] Information about each symbol type, i.e., information representing one of DL symbols, UL symbols, and flexible symbols, may be provided using cell-specific or common radio resource control (RRC) signals. In addition, information about each symbol type may be provided using UE-specific or dedicated RRC signals. The base station notifies the following using cell-specific RRC signals: i) the duration of the cell-specific slot configuration, ii) the number of slots with only DL symbols from the beginning of the cell-specific slot configuration period, iii) the number of DL symbols from the first symbol of the slot immediately following a slot with only DL symbols, iv) the number of slots with only UL symbols from the end of the cell-specific slot configuration period, and v) the number of UL symbols from the last symbol of the slot immediately preceding a slot with only UL symbols. Here, a flexible symbol is a symbol that is not configured using either a UL symbol or a DL symbol.

[0042] When information about symbol types is configured using UE-specific RRC signals, the base station can signal in the cell-specific RRC signal whether the flexible symbol is a DL symbol or a UL symbol. In this case, the UE-specific RRC signal cannot change a DL symbol or a UL symbol configured using the cell-specific RRC signal to another symbol type. The UE-specific RRC signal signals the number of DL symbols among the N symbols of the corresponding slot for each slot, and the number of UL symbols among the N symbols of the corresponding slot. In this case, the DL symbols of the slot can be continuously configured using the first symbol to the i-th symbol of the slot. In addition, the UL symbols of the slot can be continuously configured using the j-th symbol to the last symbol of the slot (where i < j). Among the slots, the symbol that is not configured using either the UL symbol or the DL symbol is the flexible symbol. slot symb The number of DL symbols among the N symbols of the corresponding slot for each slot, and the N slot symb The number of UL symbols among the N symbols of the corresponding slot can be signaled. In this case, the DL symbols of the slot can be continuously configured using the first symbol to the i-th symbol of the slot. In addition, the UL symbols of the slot can be continuously configured using the j-th symbol to the last symbol of the slot (where i < j). Among the slots, the symbol that is not configured using either the UL symbol or the DL symbol is the flexible symbol.

[0043] The type of symbol composed of the RRC signal as described above is called a semi-static DL / UL configuration. In the semi-static DL / UL configuration composed of the RRC signal described above, the flexible symbol is indicated as a downlink symbol, an uplink symbol, or a flexible symbol via the dynamic SFI (slot format information) transmitted on the physical downlink control channel (PDCCH). At this time, the downlink symbol or the uplink symbol composed of the RRC signal is not changed to another symbol type. Table 1 exemplifies the dynamic SFI indicated by the base station to the terminal.

[0044]

Table 1

[0045] In Table 1, D represents the downlink symbol, U represents the uplink symbol, and X represents the flexible symbol. As shown in Table 1, a maximum of two DL / UL switching operations are permitted in a single slot.

[0046] Figure 3 illustrates the physical channels used in 3GPP systems (e.g., NR) and a typical signal transmission method utilizing these physical channels.

[0047] When the UE is powered on or camp-on to a new cell, the UE performs an initial cell discovery (S101). Specifically, the UE may synchronize with the base station during the initial cell discovery. To this end, the UE may receive primary synchronization signals (PSS) and secondary synchronization signals (SSS) from the base station to synchronize with the base station and obtain information such as the cell ID. Subsequently, the UE may receive physical broadcast channels from the base station and obtain broadcast information in the cell.

[0048] Upon completion of the initial cell discovery, the UE receives the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) according to the information within the PDCCH. As a result, the UE can obtain more specific system information than that obtained through the initial cell discovery (S102). Here, the system information obtained by the UE is the cell-common system information necessary for the UE to operate correctly at the physical layer in the Radio Resource Control (RRC), and is also called remaining system information or system information block (SIB) 1.

[0049] When a UE first accesses a base station or does not have radio resources for signal transmission, the UE may perform a random access procedure to the base station (operations S103-S106). First, the UE can transmit a preamble through a physical random access channel (PRACH) (S103), and can receive a response message for the preamble from the base station through the PDCCH and the corresponding PDSCH (S104). Once the UE receives a valid random access response message, the UE transmits data, including the UE's identifier, to the base station through a physical uplink shared channel (PUSCH), indicated by a UL authorization transmitted from the base station via the PDCCH (S105). Next, the UE waits to receive the PDCCH as an indication from the base station for collision resolution. If the UE successfully receives the PDCCH with the UE's identifier (S106), the random access process is terminated. During the random access process, the UE can obtain UE-specific system information at the RRC layer that is necessary for the UE to operate correctly at the physical layer. When the UE obtains UE-specific system information at the RRC layer, the UE enters RRC_CONNECTED mode.

[0050] The RRC layer is used for message generation and management for control between terminals and the Radio Access Network (RAN). More specifically, base stations and terminals can perform storage management at the RRC layer, including broadcasting of cell system information required by all terminals in the cell, transmission management of paging messages, mobility management and handover, terminal measurement reporting and control therefor, terminal capability management and equipment management. In general, the update of signals transmitted at the RRC layer (hereinafter referred to as RRC signals) is longer than the transmission time interval (i.e., TTI) at the physical layer, so RRC signals can be maintained unchanged over long periods.

[0051] After the procedure described above, the UE receives the PDCCH / PDSCH (S107) and transmits the physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) as a general UL / DL signal transmission procedure (S108). Specifically, the UE may receive downlink control information (DCI) through the PDCCH. The DCI may include control information such as resource allocation information for the UE. The format of the DCI may also vary depending on the intended use. The uplink control information (UCI) that the UE transmits to the base station through the UL includes DL / UL ACK / NACK signals, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), etc. Here, the CQI, PMI, and RI may be included in the channel state information (CSI). In a 3GPP NR system, the UE may transmit control information such as the HARQ-ACK and CSI described above via PUSCH and / or PUCCH.

[0052] Figures 4a and 4b show the SS / PBCH block for initial cell access in the 3GPP NR system.

[0053] When powered on or when a new cell is desired, the UE can obtain time and frequency synchronization with the cell and perform the initial cell discovery procedure. During the cell discovery procedure, the UE can discover the cell's physical cell identification information, NcellID. To this end, the UE can receive synchronization signals from the base station, such as a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and synchronize with the base station. In this case, the UE can obtain information such as the cell identification information (ID).

[0054] The synchronization signal (SS) will be explained in more detail with reference to Figure 4a. Synchronization signals can be classified into PSS and SSS. PSS can be used to obtain time-domain synchronization and / or frequency-domain synchronization, such as OFDM symbol synchronization and slot synchronization. SSS can be used to obtain frame synchronization and cell group ID. Referring to Figure 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. In this case, within the SS / PBCH block, the PSS is transmitted in the first OFDM symbol and the SSS is transmitted in the third OFDM symbol through subcarriers 56 to 182. Here, the smallest subcarrier index in the SS / PBCH block is numbered from 0. In the first OFDM symbol in which the PSS is transmitted, the base station does not transmit signals through the remaining subcarriers, i.e., subcarriers 0 to 55 and 183 to 239. In addition, in the third OFDM symbol transmitted within the SSS, the base station does not transmit signals through subcarriers 48-55 and 183-191. The base station transmits the physical broadcast channel (PBCH) through the remaining REs within the SS / PBCH block, excluding the aforementioned signals.

[0055] [Table 2]

[0056] SS allows a total of 1008 unique physical layer cell IDs to be grouped into 336 physical layer cell identifier groups, each group containing three unique identifiers through three PSS and SSS combinations, such that each physical layer cell ID is part of only one physical layer cell identifier group. Thus, physical layer cell ID N cell ID =3N (1) ID +N (2) ID This represents an index N ranging from 0 to 335, indicating a physical layer cell identifier group. (1) ID , and an index N ranging from 0 to 2, indicating the physical layer identifier within the physical layer cell identifier group. (2) ID This can be uniquely defined by the following. The UE can detect the PSS and identify one of the three unique physical layer identifiers. In addition, the UE can detect the SSS and identify one of the 336 physical layer cell IDs associated with the physical layer identifier. In this case, the PSS sequence d PSS (n) is as follows:

number

[0057] Here

number

number

[0058] Furthermore, the SSS series dSSS (n) is as follows:

number

[0059] Here

number

number

[0060] A radio frame with a length of 10 ms can be divided into two half-frames with a length of 5 ms. Referring to Figure 4b, the slot in which the SS / PBCH block is transmitted within each half-frame is described. The slot in which the SS / PBCH block is transmitted may be any one of cases A, B, C, D, and E. In case A, the subcarrier spacing is 15 kHz, and the start of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, n=0 or 1 at carrier frequencies below 3 GHz. In addition, n may be 0, 1, 2, or 3 at carrier frequencies above 3 GHz and below 6 GHz. In case B, the subcarrier spacing is 30 kHz, and the start of the SS / PBCH block is {4,8,16,20}+28*n. In this case, n=0 at carrier frequencies below 3 GHz. In addition, n may be 0 or 1 at carrier frequencies above 3 GHz and below 6 GHz. In Example C, the subcarrier spacing is 30 kHz, and the start of the SS / PBCH block is the ({2,8}+14*n)th symbol. In this case, n=0 or 1 at carrier frequencies below 3 GHz. In addition, n may be 0, 1, 2, or 3 at carrier frequencies above 3 GHz and below 6 GHz. In Example D, the subcarrier spacing is 120 kHz, and the start of the SS / PBCH block is the ({4,8,16,20}+28*n)th symbol. In this case, n is 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, or 18 at carrier frequencies above 6 GHz. In Example E, the subcarrier spacing is 240 kHz, and the start of the SS / PBCH block is the ({8,12,16,20,32,36,40,44}+56*n)th symbol. In this case, for carrier frequencies above 6 GHz, n = 0, 1, 2, 3, 5, 6, 7, 8.

[0061] Figures 5a and 5b illustrate the procedures for transmitting control information and control channels in a 3GPP NR system. Referring to Figure 5a, a base station may add a cyclic redundancy check (CRC) masked (e.g., by XOR operation) using a radio network temporary identifier (RNTI) to the control information (e.g., downlink control information (DCI)) (S202). The base station may scramble the CRC using an RNTI value determined according to the purpose / target of each piece of control information. A common RNTI used by one or more UEs may include at least one of the following: system information RNTI (SI-RNTI), paging RNTI (P-RNTI), random access RNTI (RA-RNTI), and transmit power control RNTI (TPC-RNTI). In addition, UE-specific RNTIs may include at least one of the following: cell temporary RNTI (C-RNTI) and CS-RNTI. Subsequently, the base station may perform channel coding (e.g., polar coding) (S204) and then perform rate matching according to the amount of resources used for PDCCH transmission (S206). The base station may then multiplex the DCI based on a control channel element (CCE)-based PDCCH structure (S208). In addition, the base station may apply additional processes such as scrambling, modulation (e.g., QPSK), and interleaving to the multiplexed DCI (S210), and then map the DCI to the resources to be transmitted. A CCE is the basic resource unit for a PDCCH, and one CCE may contain multiple (e.g., six) resource element groups (REGs). One REG may consist of multiple (e.g., twelve) REs. The number of CCEs used for one PDCCH may be defined as the aggregation level.In 3GPP NR systems, aggregation levels 1, 2, 4, 8, or 16 may be used. Figure 5b is a diagram relating CCE aggregation levels and PDCCH multiplexing, showing the type of CCE aggregation level used for a single PDCCH and the CCE transmitted within the control area accordingly.

[0062] Figure 6 shows the set of control resources (core set) that a physical downlink control channel (PDCCH) can transmit within in a 3GPP NR system.

[0063] A coreset is a time-frequency resource in which PDCCHs, i.e., control signals for the UE, are transmitted. In addition, a search space, which will be described later, may be mapped to a coreset. Thus, a UE may monitor a time-frequency domain designated as a coreset, rather than monitoring all frequency bands for PDCCH reception, and can decode the PDCCH mapped to the coreset. A base station may configure one or more coresets per cell for the UE. A coreset may be configured using up to three consecutive symbols on the time axis. In addition, a coreset may be configured in units of six consecutive PRBs on the frequency axis. In the embodiment of Figure 6, coreset #1 is configured using consecutive PRBs, and coresets #2 and #3 are configured using non-contiguous PRBs. A coreset may be placed in any symbol within a slot. For example, in the embodiment of Figure 6, 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.

[0064] Figure 7 shows a method for setting up the PDCCH search space in the 3GPP NR system.

[0065] To transmit a PDCCH to a UE, each core set may have at least one search space. In embodiments of this disclosure, the search space is a set of all time-frequency resources through which a UE's PDCCH can be transmitted (hereinafter, PDCCH candidates). The search space may include a common search space that all UEs of 3GPP NR are required to search in common, and terminal-specific or UE-specific search spaces that a particular UE is required to search. In the common search space, a UE may monitor a PDCCH that is set up to be searched in common by all UEs in a cell belonging to the same base station. In addition, UE-specific search spaces may be set up per UE so that a UE monitors a PDCCH allocated to each UE at different search space locations according to the UE. In the case of UE-specific search spaces, the search spaces between UEs may partially overlap or be allocated due to the limited control area through which a PDCCH is allocated. Monitoring a PDCCH involves blind decoding to find PDCCH candidates in the search space. When blind decoding is successful, it may be expressed that the PDCCH has been (successfully) detected / received, and when blind decoding fails, it may be expressed that the PDCCH has not been detected / received, or has not been successfully detected / received.

[0066] For the sake of explanation, a PDCCH scrambled using a group-common (GC) RNTI previously known to one or more UEs to send DL control information to one or more UEs is called a group-common (GC) PDCCH or common PDCCH. In addition, a PDCCH scrambled using a terminal-specific RNTI already known to a particular UE to send UL scheduling information or DL ​​scheduling information to a particular UE is called a UE-specific PDCCH. Common PDCCHs may be contained within a common search space, and UE-specific PDCCHs may be contained within a common search space or within a UE-specific PDCCH.

[0067] A base station may signal to each UE or UE group via the PDCCH about information relating to resource allocation for the transmission channels, namely the paging channel (PCH) and the downlink-shared channel (DL-SCH) (i.e., DL permission), or information relating to resource allocation for the uplink-shared channel (UL-SCH) and Hybrid Automatic Retransmission Request (HARQ) (i.e., UL permission). The base station may transmit PCH transport blocks and DL-SCH transport blocks via the PDSCH. The base station may transmit data, excluding certain control information or certain service data, via the PDSCH. In addition, UEs may receive data, excluding certain control information or certain service data, via the PDSCH.

[0068] A base station may include information in a PDCCH about where the UE(s) PDSCH data will be transmitted to and how the corresponding UE will receive and decode the PDSCH data, and may transmit such a PDCCH. For example, suppose a DCI transmitted on a particular PDCCH is CRC masked using an RNTI named "A", and the DCI indicates that the PDSCH is allocated to a radio resource (e.g., frequency location) named "B", and indicates transmission format information (e.g., transport block size, modulation scheme, coding information, etc.) named "C". A UE monitors the PDCCH using the RNTI information it possesses. In this case, if there is a UE performing blind decoding of the PDCCH using the RNTI of "A", that UE will receive the PDCCH and, through the received PDCCH information, receive the PDSCH indicated by "B" and "C".

[0069] Table 3 shows one embodiment of a physical uplink control channel (PUCCH) used in a wireless communication system.

[0070] [Table 3]

[0071] PUCCH can be used to transmit the following UL control information (UCI):

[0072] - Scheduling Request (SR): Information used to request UL-SCH resources.

[0073] - HARQ-ACK: A response to the PDCCH (indicating DL SPS release) and / or to the DL transport block (TB) on the PDSCH. HARQ-ACK indicates whether information transmitted on the PDCCH or PDSCH has been received. HARQ-ACK responses include positive ACK (simply ACK), negative ACK (hereinafter, NACK), discontinuous transmission (DTX), or NACK / DTX. Here, the term HARQ-ACK is used in conjunction with HARQ-ACK / NACK and ACK / NACK. Generally, ACK may be represented by a bit value of 1, and NACK may be represented by a bit value of 0.

[0074] - Channel Status Information (CSI): Feedback information on the DL channel. The UE generates it based on the CSI reference signal (RS) transmitted by the base station. Multi-input multiple-output (MIMO) related feedback information includes a rank indicator (RI) and a precoding matrix indicator (PMI). The CSI can be divided into CSI part 1 and CSI part 2 according to the information indicated by the CSI.

[0075] The 3GPP NR system may use five PUCCH formats to support various service scenarios, channel environments, and frame structures.

[0076] PUCCH format 0 is a format capable of transmitting 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 0 can be transmitted through one or two OFDM symbols on the time axis and one RB on the frequency axis. When PUCCH format 0 is transmitted through two OFDM symbols, the same sequence on the two symbols may be transmitted through different RBs. In this case, the sequence may be a sequence that has been cyclically shifted (CS) from the base sequence used in PUCCH format 0. Through this, the UE can obtain frequency diversity gain. Specifically, the terminal is M bit Bit UCI(M bit =1 or 2) The cyclic shift (CS) value m cs It is possible to determine this. Also, a basic series of length 12 can be determined by a defined CS value m cs Based on this, a cyclically shifted sequence can be mapped to 12 REs, each consisting of one OFDM symbol and one RB, and transmitted. The number of cyclic shifts available to the terminal is 12, and M bit If = 1, then the 1-bit UCI 0 and 1 can be mapped to two cyclically shifted sequences, respectively, where the difference in cyclic shift values ​​is 6. Also, M bit If = 2, the 2-bit UCIs 00, 01, 11, and 10 can each be mapped to four cyclically shifted sequences, each with a cyclic shift value difference of 3.

[0077] PUCCH format 1 transmits 1-bit or 2-bit HARQ-ACK information or SR. PUCCH format 1 is transmitted via a continuous sequence of OFDM symbols on the time axis and a single PRB on the frequency axis. Here, the number of OFDM symbols occupied by PUCCH format 1 is one of 4 to 14. For more details, see M bit UCI with =1 is modulated by BPSK. The terminal is M bitThe UCI, which is equal to 2, is modulated using QPSK (quadrature phase shift keying). A signal is obtained by multiplying the modulated complex valued symbol d(0) by a sequence of length 12. The terminal transmits the obtained signal by spreading it with time-axis OCC (orthogonal cover code) to the even-numbered OFDM symbols to which PUCCH format 1 is assigned. The maximum number of different terminals that can be multiplexed with the same RB is determined by the length of the OCC used in PUCCH format 1. The DMRS (demodulation reference signal) is spread with OCC and mapped to the odd-numbered OFDM symbols of PUCCH format 1.

[0078] PUCCH format 2 can deliver UCIs of more than 2 bits. PUCCH format 2 can be transmitted through one or two OFDM symbols on the time axis and one or more RBs on the frequency axis. When PUCCH format 2 is transmitted through two OFDM symbols, the sequences transmitted through the two OFDM symbols in different RBs may be the same as each other. Here, the sequence is a plurality of modulated complex number symbols d(0),···,d(M symbol -1) is acceptable. Here, M symbol is M bit It may be / 2. Through this, the UE can obtain frequency diversity gain. More specifically, M bit Bit UCI(M bit >2) is bit-level scrambled, QPSK modulated, and mapped to one or two OFDM symbols, where the number of RBs can be one between 1 and 16.

[0079] PUCCH format 3 or PUCCH format 4 can deliver UCIs of more than 2 bits. PUCCH format 3 or PUCCH format 4 can be transmitted through a sequence of OFDM symbols on the time axis and one PRB on the frequency axis. The number of OFDM symbols occupied by PUCCH format 3 or PUCCH format 4 may be one of 4 to 14. Specifically, the UE uses π / 2-2 phase shift keying (BPSK) or QPSK for M bit Modulate the bit UCI (Mbit>2) to obtain the complex value symbol d(0)~d(M symb -1) is generated. Here, when using π / 2-BPSK, M symb =M bit And when using QPSK, M symb =M bit The value is / 2. The UE does not have to apply block-based spread to PUCCH format 3. However, the UE may apply block-based spread to one RB (i.e., 12 subcarriers) using a PreDFT-OCC of length 12 such that PUCCH format 4 may have a multiplexing capacity of 2 or 4. The UE performs transmit precoding (or DFT precoding) on ​​the spread signal and maps it to each RE to transmit the spread signal.

[0080] In this case, the number of RBs occupied by PUCCH format 2, PUCCH format 3, or PUCCH format 4 may be determined according to the length and maximum code rate of the UCI transmitted by the UE. When the UE uses PUCCH format 2, the UE may transmit HARQ-ACK information and CSI information together through PUCCH. If the number of RBs that the UE can transmit is greater than the maximum number of RBs that PUCCH format 2, PUCCH format 3, or PUCCH format 4 can use, the UE may transmit only the remaining UCI information without transmitting some of the UCI information, according to the priority of the UCI information.

[0081] PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured through an RRC signal to indicate frequency hopping within a slot. When frequency hopping is configured, the index of the RB to be frequency-hopped may be configured using the RRC signal. When PUCCH format 1, PUCCH format 3, or PUCCH format 4 is transmitted through N OFDM symbols on the time axis, the first hop may have floor(N / 2) OFDM symbols, and the second hop may have ceil(N / 2) OFDM symbols.

[0082] PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured to be transmitted repeatedly in multiple slots. In this case, the number K of slots in which the PUCCH is transmitted repeatedly may be determined by the RRC signal. The repeatedly transmitted PUCCH must begin at a fixed position OFDM symbol in each slot and must be of a constant length. When one of the OFDM symbols in a slot in which the UE is to transmit the PUCCH is indicated as a DL symbol by the RRC signal, the UE does not have to transmit the PUCCH in the corresponding slot and may delay the transmission of the PUCCH until the next slot in which it is to be transmitted.

[0083] On the other hand, in a 3GPP NR system, a terminal can transmit and receive using a bandwidth smaller than or equal to the carrier (or cell) bandwidth. To this end, a terminal may have a bandwidth part (BWP) consisting of a contiguous portion of the carrier bandwidth. A terminal operating by TDD or in an unpaired spectrum may have up to four DL / UL BWP pairs per carrier (or cell). A terminal can also activate one DL / UL BWP pair. A terminal operating by FDD or in a paired spectrum may have up to four DL BWPs per downlink carrier (or cell) and up to four UL BWPs per uplink carrier (or cell). A terminal can activate one DL BWP and one UL BWP per carrier (or cell). A terminal does not need to receive or transmit on time-frequency resources other than the activated BWPs. Activated BWPs can be called active BWPs.

[0084] A base station can indicate to a terminal which of the configured BWPs (bandwidth points) are activated using downlink control information (DCI). The BWP indicated in the DCI is activated, and the other configured BWPs are deactivated. In a carrier (or cell) operating in TDD mode, the base station may include a bandwidth part indicator (BPI) indicating the activated BWP in the DCI that schedules a PDSCH or PUSCH to change the terminal's DL / UL BWP pair. The terminal can receive the DCI that schedules the PDSCH or PUSCH and identify the activated DL / UL BWP pair based on the BPI. In a downlink carrier (or cell) operating in FDD mode, the base station may include a BPI indicating the activated BWP in the DCI that schedules a PDSCH to change the terminal's DL BWP. In an uplink carrier (or cell) operating in FDD mode, the base station may include a BPI indicating the activated BWP in the DCI that schedules a PUSCH to change the terminal's UL BWP.

[0085] Figure 8 is a conceptual diagram illustrating carrier aggregation.

[0086] Carrier aggregation is a method by which a wireless communication system uses a wider frequency band by allowing a UE (Unified Element) to use multiple frequency blocks or cells (in a logical sense) composed of UL resources (or component carriers) and / or DL ​​resources (or component carriers) as one large logical frequency band. A single component carrier may also be referred to as a primary cell (PCell), secondary cell (SCell), or primary SCell (PScell). However, for the sake of explanation, the term "component carrier" will be used below.

[0087] Referring to Figure 8, as an example of a 3GPP NR system, the overall system bandwidth may include up to 16 component carriers, each component carrier may have a bandwidth of up to 400 MHz. A component carrier may include one or more physically continuous subcarriers. Although Figure 8 shows that each component carrier has the same bandwidth, this is just an example, and each component carrier may have a different bandwidth. Also, although each component carrier is shown as adjacent to each other on the frequency axis, the diagram is shown in a logical concept, and each component carrier may be physically adjacent to each other or separated from each other.

[0088] A different center frequency may be used for each component carrier. Alternatively, a single common center frequency may be used for physically adjacent component carriers. In the embodiment shown in Figure 8, assuming that all component carriers are physically adjacent, center frequency A may be used for all component carriers. Furthermore, assuming that the component carriers are not physically adjacent to each other, center frequencies A and B may be used for each component carrier.

[0089] When the entire system bandwidth is extended by carrier aggregation, the frequency bandwidth used for communication with each UE can be defined in units of component carriers. UE A may use the entire system bandwidth of 100 MHz and communicate using all five component carriers. UEs B1-B5 may use only 20 MHz bandwidth and communicate using one component carrier. UEs C1 and C2 may use 40 MHz bandwidth and communicate using two component carriers each. The embodiment in Figure 8 shows that UEC1 uses two non-adjacent component carriers and UEC2 uses two adjacent component carriers.

[0090] Figure 9 illustrates single-carrier and multi-carrier communication. Specifically, Figure 9(a) shows a single-carrier subframe structure, and Figure 9(b) shows a multi-carrier subframe structure.

[0091] Referring to Figure 9(a), in FDD mode, a typical wireless communication system may perform data transmission or data reception through one DL band and one UL band, respectively. In another specific embodiment, in TDD mode, the wireless communication system may divide the radio frame in the time domain into UL time units and DL time units, and perform data transmission or data reception through the UL / DL time units. Referring to Figure 9(b), three 20 MHz component carriers (CCs) can be aggregated into UL and DL, respectively, to support a 60 MHz bandwidth. Each CC may or may not be adjacent to each other in the frequency domain. Figure 9(b) shows an example where the bandwidths of the UL CCs and DL CCs are identical and symmetric, but the bandwidths of each CC can be determined independently. In addition, asymmetric carrier aggregations with different numbers of UL CCs and DL CCs are possible. DL / UL CCs allocated / configured to a particular UE through RRC are sometimes called the serving DL / UL CCs of that particular UE.

[0092] A base station may communicate with a UE by activating some or all of the UE's serving CCs, or by deactivating some of the CCs. The base station may change which CCs are to be activated / deactivated, and may change the number of CCs to be activated / deactivated. If the base station allocates CCs available to a UE as cell-specific or UE-specific, at least one of the allocated CCs may be deactivated unless the CC allocation to the UE is completely reconfigured or the UE is handed over. The CC that is not deactivated by the UE is called the Primary CC (PCC) or Primary Cell (PCell), and the CC that the base station can freely activate / deactivate is called the Secondary CC (SCC) or Secondary Cell (SCell).

[0093] On the other hand, 3GPP NR uses the concept that a cell manages radio resources. A cell is defined as a combination of DL resources and UL resources, i.e., a combination of DL CC and UL CC. A cell may consist of DL resources only, or a combination of DL resources and UL resources. When carrier aggregation is supported, the coordination between the carrier frequencies of DL resources (i.e., DL CC) and UL resources (i.e., UL CC) may be indicated by system information. The carrier frequency refers to the center frequency of each cell or CC. A cell corresponding to a PCC is called a PCell, and a cell corresponding to an SCC is called a SCell. The carrier corresponding to a PCell in DL is a DL PCC, and the carrier corresponding to a PCell in UL is a UL PCC. Similarly, the carrier corresponding to a SCell in DL is a DL SCC, and the carrier corresponding to a SCell in UL is a UL SCC. Depending on the UE capability, a serving cell may consist of one PCell and zero or more SCells. If a UE is in the RRC_CONNECTED state but is not configured for or does not support carrier aggregation, it will have only one serving cell configured using only PCells.

[0094] As described above, the term "cell" as used in carrier aggregation is distinct from the term "cell" which refers to several geographical areas where communication services are provided by a single base station or antenna group. That is, a single component carrier may also be called a scheduling cell, scheduled cell, primary cell (PCell), secondary cell (SCell), or primary SCell (PScell). However, in order to distinguish between cells referring to several geographical areas and cells in carrier aggregation, in this disclosure, cells in carrier aggregation are referred to as CCs, and cells in geographical areas are referred to as cells.

[0095] Figure 10 shows an example where the cross-carrier scheduling technique is applied. When cross-carrier scheduling is set up, a control channel transmitted through the 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 set up, and DL / UL permissions transmitted within the PDCCH area of ​​the scheduling cell schedule the PDSCH / PUSCH of the scheduled cell. That is, a search area for multiple component carriers exists within the PDCCH area of ​​the scheduling cell. A PCell can essentially be a scheduling cell, and a particular SCell may be designated as a scheduling cell by a higher layer.

[0096] In the embodiment shown in Figure 10, it is assumed that three DL CCs are merged. Here, it is assumed that DL component carrier #0 is a DL PCC (or PCell), and DL component carriers #1 and #2 are DL SCCs (or SCells). In addition, it is assumed that the DL PCC is configured as a PDCCH that monitors CCs. When 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 send only a PDCCH to schedule its PDSCH without using 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 UE-specific (or UE group-specific or cell-specific) upper-layer signaling, CIF is enabled, and a particular CC (e.g., DL PCC) may send not only a PDCCH to schedule the PDSCH of DL CC A using CIF, but also a PDCCH to schedule the PDSCH of another CC (cross-carrier scheduling). On the other hand, PDCCH is not transmitted within another DL CC. Therefore, depending on whether cross-carrier scheduling is configured for the UE, the UE will either monitor a PDCCH without a CIF to receive a self-carrier scheduled PDSCH, or monitor a PDCCH with a CIF to receive a cross-carrier scheduled PDSCH.

[0097] On the other hand, Figures 9 and 10 show the subframe structure of a 3GPP LTE-A system, and the same or a similar configuration may be applied to a 3GPP NR system. However, in a 3GPP NR system, the subframes in Figures 9 and 10 may be replaced with slots.

[0098] Figure 11 is a block diagram showing the configurations of a terminal and a base station according to one embodiment of the present disclosure.

[0099] In the embodiments of this disclosure, the terminal can be embodied as various wireless communication devices or computer devices that ensure portability and mobility. The terminal may also be referred to as UE (User Equipment), STA (Station), MS (Mobile Subscriber), etc. Furthermore, in the embodiments of this disclosure, the base station may control and manage cells (e.g., macrocells, femtocells, picocells, etc.) corresponding to the service area and have functions such as signal transmission, channel assignment, channel monitoring, self-diagnosis, and relaying. The base station may also be referred to as gNB (next Generation Node B) or AP (Access Point), etc.

[0100] As shown in the figures, a terminal 100 according to one embodiment of the present disclosure may include a processor 110, a communication module 120, a memory 130, a user interface 140, and a display unit 150.

[0101] First, the processor 110 can execute various instructions or programs and process data inside the terminal 100. Furthermore, the processor 110 can control the overall operation of the terminal 100, including each unit, and control data transmission and reception between units. Here, the processor 110 may be configured to perform the operations described in the embodiments of this disclosure. For example, the processor 110 can receive slot configuration information, determine the slot configuration based on this information, and perform communication according to the determined slot configuration.

[0102] Next, the communication module 120 may be an integrated module that performs wireless communication using a wireless communication network and wireless LAN connection using a wireless LAN. For this purpose, the communication module 120 may be equipped with multiple network interface cards (NICs), such as cellular communication interface cards 121 and 122 and an unlicensed band communication interface card 123, either internally or externally. In the figure, the communication module 120 is shown as a single integrated module, but each network interface card may be arranged independently depending on the circuit configuration or application, contrary to the drawing.

[0103] The cellular communication interface card 121 can transmit and receive wireless signals to and from at least one of a base station 200, an external device, or a server using a mobile communication network, and provide cellular communication services in a first frequency band based on instructions from the processor 110. According to one embodiment, the cellular communication interface card 121 may include at least one NIC module that uses a frequency band of less 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, or a server in accordance with a cellular communication standard or protocol in a frequency band of less than 6 GHz supported by the NIC module.

[0104] The cellular communication interface card 122 can transmit and receive wireless signals to and from at least one of a base station 200, an external device, or a server using a mobile communication network, and can provide cellular communication services in a second frequency band based on instructions from the processor 110. In one embodiment, the cellular communication interface card 122 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 122 can independently perform cellular communication with at least one of the base station 200, an external device, or a server in accordance with a cellular communication standard or protocol in a frequency band of 6 GHz or higher supported by the NIC module.

[0105] The unlicensed band communication interface card 123 uses a third frequency band, which is an unlicensed band, to send and receive wireless signals with at least one of the base station 200, an external device, or a server, and provides communication services in the unlicensed band based on instructions from 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 2.4GHz, 5GHz, 6GHz, 7GHz, or 52.6GHz or higher. At least one NIC module of the unlicensed band communication interface card 123 can communicate wirelessly with at least one of the base station 200, an external device, or a server, independently or dependently, in accordance with the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0106] Next, the memory 130 stores the control program used by the terminal 100 and various data associated with it. Such a control program may include a predetermined program necessary for the terminal 100 to perform wireless communication with at least one of the base station 200, an external device, or a server.

[0107] Next, the user interface 140 includes various forms 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. Furthermore, the user interface 140 can output based on instructions from the processor 110 using various output means.

[0108] Next, the display unit 150 outputs various images to the display screen. The display unit 150 can output various display objects such as content executed by the processor 110 or user interfaces based on control instructions of the processor 110.

[0109] Furthermore, the base station 200 according to one embodiment of the present disclosure may include a processor 210, a communication module 220, and a memory 230.

[0110] First, the processor 210 can execute various instructions or programs and process data within the base station 200. Furthermore, the processor 210 can control the overall operation of the base station 200, including each unit, and control data transmission and reception between units. Here, the processor 210 may be configured to perform the operations described in the embodiments of this disclosure. For example, the processor 210 can signal slot configuration information and communicate according to the signaled slot configuration.

[0111] Next, the communication module 220 may be an integrated module that performs wireless communication using a wireless communication network and wireless LAN connection using a wireless LAN. For this purpose, the communication module 220 may be equipped with multiple network interface cards, such as cellular communication interface cards 221 and 222 and an unlicensed band communication interface card 223, either internally or externally. In the figure, the communication module 220 is shown as a single integrated module, but each network interface card may be arranged independently depending on the circuit configuration or application, contrary to the drawing.

[0112] The cellular communication interface card 221 can transmit and receive wireless signals to and from at least one of the terminal 100, external devices, and servers described above using a mobile communication network, and can provide cellular communication services in the first frequency band based on instructions from the processor 210. In one embodiment, the cellular communication interface card 221 may include at least one NIC module that uses a frequency band of less 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 devices, and servers in accordance with a cellular communication standard or protocol in a frequency band of less than 6 GHz supported by the NIC module.

[0113] The cellular communication interface card 222 can transmit and receive wireless signals to and from at least one of the terminal 100, an external device, and a server using a mobile communication network, and can provide cellular communication services in a second frequency band based on instructions from the processor 210. According to one embodiment, the cellular communication interface card 222 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 222 can independently perform cellular communication with at least one of the terminal 100, an external device, and a server in accordance with a cellular communication standard or protocol of a frequency band of 6 GHz or higher that the NIC module supports.

[0114] The unlicensed band communication interface card 223 uses a third frequency band, which is an unlicensed band, to send and receive wireless signals with at least one of the terminal 100, an external device, or a server, and provides communication services in the unlicensed band based on instructions from 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 2.4GHz, 5GHz, 6GHz, 7GHz, or 52.6GHz or higher. At least one NIC module of the unlicensed band communication interface card 223 can communicate wirelessly with at least one of the terminal 100, an external device, or a server, independently or dependently, in accordance with the unlicensed band communication standard or protocol of the frequency band supported by the NIC module.

[0115] The terminal 100 and base station 200 shown in Figure 11 are block diagrams according to one embodiment of the present invention, and the separately displayed blocks logically distinguish and show the elements of the device. Therefore, the above-described elements of the device may be mounted as a single chip or as multiple chips depending on the device design. 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. Furthermore, the user interface 140 and the display unit 150, etc., may be further provided in the base station 200 as needed.

[0116] A terminal can receive a Physical Downlink Control Channel (PDCCH) transmitted from a base station. In order for the terminal to receive the Downlink Control Channel from the base station, information such as a control resource set (CORESET) or search space may be configured on the terminal.

[0117] The control resource set may include information in the frequency domain where the physical downlink control channel should be received. Specifically, a base station can provide a terminal with information about the control resource set, which may include the index of the PRB (Physical Resource Block) or PRB set from which the terminal should receive the physical downlink control channel, and the number of consecutive symbols. In this case, the number of consecutive symbols may be one of 1, 2, or 3.

[0118] The search space may include time information for receiving the set of PRBs specified in the control resource set. Specifically, the base station can provide the terminal with information about the search space, which may include at least one of the following: periodicity and offset. Here, the periodicity and offset may be set in units of slots, sub-slots, symbols, sets of symbols, or sets of slots. The information about the search space may include the CCE aggregation level (AL) received by the terminal, the number of PDCCHs monitored by the terminal for each CCE aggregation level, the search space type, the DCI format monitored by the terminal, and RNTI information.

[0119] The CCE integration level may have at least one value from 1, 2, 4, 8, or 16. The terminal can monitor PDCCH with the same number of CCEs as the value of the CCE integration level.

[0120] Search spaces can be distinguished into two types. Specifically, search spaces can be distinguished into common search spaces (CSS) and terminal-specific search spaces (UE-specific search spaces). A common search space may be a search space in which all terminals in a cell or some terminals in a cell commonly monitor PDCCHs. Terminals can receive PDCCHs by monitoring candidate PDCCHs (for example, PDCCHs that transmit DCIs having a CRC scrambled with at least one RNTI from 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, or PS-RNTI) broadcast in the common search space to all terminals in a cell or some terminals in a cell. The terminal-specific search space may be a search space in which a specific terminal monitors PDCCHs. The specific terminal can monitor candidates for PDCCHs (for example, PDCCHs that transmit a DCI having a CRC scrambled with at least one RNTI from among C-RNTI, MCS-C-RNTI, SP-CSI-RNTI, CS-RNTI, SL-RNTI, SL-CS-RNTI, or SL-L-CS-RNTI) transmitted to the specific terminal in the terminal-specific search space and receive PDCCHs. The terminal can also receive PDCCHs in the common search space and the terminal-specific search space that include a DCI instructing the reception of a physical downlink sharing channel, the transmission of a physical uplink control channel, or the transmission of a physical uplink sharing channel.

[0121] The DCI format monitored by a terminal scheduled to transmit PUSCH and receive PDSCH from a base station may be DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, and 1_2. RNTI information in DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, and 1_2 may include at least one of CS-RNTI, MCS-C-RNTI, and C-RNTI. Here, CS-RNTI may be used to activate / release semi-persistent scheduling (SPS) PDSCH or configured grant (CG) PUSCH. CS-RNTI may also be used to schedule retransmission of SPS PDSCH or CG PUSCH. Here, MCS-C-RNTI may be used to schedule PDSCH or PUSCH using a highly reliable MCS (modulation and coding scheme). C-RNTI may be used to schedule PDSCH or PUSCH.

[0122] The DCI format that may be included in the PDCCH monitored by the terminal may further include the following information:

[0123] DCI format 2_0 may include information about a Dynamic Slot Format Indicator (SFI) that specifies the orientation of the symbols constituting the slot. In this case, the symbol orientation may be uplink, downlink, or flexible. Symbols with an uplink orientation are used for uplink transmission, symbols with a downlink orientation are used for downlink reception, and symbols with a flexible orientation may be used for both uplink transmission and downlink reception. The RNTI used for DCI format 2_0 may be an SFI-RNTI.

[0124] DCI format 2_1 may include a DL preemption indication or interrupted transmission indication that indicates there is no PRB (Pre-Range Breakback) or symbolic downlink transmission by the base station to the terminal. The RNTI used for DCI format 2_1 may be an INT-RNTI.

[0125] DCI format 2_4 may include an uplink cancellation indicator (UL cancellation indication) that instructs a terminal to cancel an uplink transmission on the PRB to a base station. The RNTI used for DCI format 2_4 may be a CI-RNTI.

[0126] The terminal can determine PDCCH candidates that should receive a PDCCH based on the configured control resource set and search space information. The terminal can monitor the PDCCH candidates, check the CRC using the RNTI value, and then determine whether an accurate PDCCH has been received. The RNTI value can include at least C-RNTI, MCS-C-RNTI, CS-RNTI, as well as SFI-RNTI, INT-RNTI, and CI-RNTI values.

[0127] When a terminal receives a PDCCH, it can decode information about the control resource set and search space based on the DCI contained in the PDCCH and perform the action indicated by the DCI. In this case, the format of the DCI contained in the PDCCH received by the terminal may be one of the DCI formats 0_0, 0_1, or 0_2 that schedule a PUSCH. Alternatively, the format of the DCI contained in the PDCCH received by the terminal may be one of the DCI formats 1_0, 1_1, or 1_2 that schedule a PDSCH. Alternatively, the format of the DCI contained in the PDCCH received by the terminal may be one of the DCI formats 1_0, 1_1, or 1_2 that schedule a PUCCH. In this case, the PUCCH may contain HARQ-ACK information. Additionally, the format of the DCI contained in the PDCCH received by the terminal may be one of the DCI formats 2_0, 2_1, or 2_4.

[0128] When a terminal receives a DCI in DCI format 1_0, 1_1, or 1_2 that schedules a PDSCH, the terminal can receive the PDSCH scheduled by the DCI. To do this, the terminal must determine the scheduled slot of the PDSCH, the starting index of the symbols within the slot, and the length (number of symbols) based on the received DCI. The TDRA (time domain resource assignment) field of the DCI in DCI format 1_0, 1_1, or 1_2 received by the terminal may indicate the K0 value, which is the timing information of the scheduled slot, and the SLIV (starting length indicator value), which is the index and length of the starting symbols within the slot. Here, the value of K0 may be a non-negative integer. Here, SLIV may be a joint-encoded value of the index (S) and length (L) of the starting symbols within the slot. The index (S) and length (L) of the starting symbols within the slot may be values ​​transmitted separately. Here, in a normal CP, S may have one value from 0, 1, ..., 13. In this case, L may be one of the natural numbers that satisfy the condition S+L is less than or equal to 14. In the extended CP, S may be one of the values ​​0, 1, ..., 11. In this case, L may be one of the natural numbers that satisfy the condition S+L is less than or equal to 12.

[0129] The terminal can determine which slot should receive the PDSCH based on the K0 value. Specifically, it can determine which slot should receive the PDSCH based on the K0 value, the index of the slot where the DCI is received, the subcarrier spacing (SCS) of the downlink BWP that received the DCI, and the subcarrier spacing of the downlink BWP that receives the scheduled PDSCH.

[0130] For example, the subcarrier interval of the downlink BWP receiving the DCI and the downlink BWP receiving the scheduled PDSCH may be the same, and the DCI may be 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 the slot having index x, or the x-th slot.

[0131] For example, the subcarrier interval of a downlink BWP receiving a DCI is 15kHz*2^mu_PDCCH, and the subcarrier interval of a downlink BWP receiving a scheduled PDSCH is 15kHz*2^mu_PDSCH, and a terminal may receive a DCI in downlink slot n. The index of downlink slot n may be an index based on the subcarrier interval of the downlink BWP from which the terminal receives the DCI. In this case, the terminal can receive a PDSCH in slot floor(n*2^mu_PDSCH / 2^mu_PDCCH)+K0. In this case, floor(n*2^mu_PDSCH / 2^mu_PDCCH)+K0 may be an index determined by the subcarrier interval of the downlink BWP from which the PDSCH is transmitted. mu_PDCCH and mu_PDSCH may have values ​​of 0, 1, 2, or 3.

[0132] Figure 12 shows the scheduling of a physical downlink shared channel according to one embodiment of the present invention.

[0133] Referring to Figure 12, the terminal can receive a PDCCH that schedules a PDSCH in downlink slot (DL slot) n. The DCI included in the PDCCH can be specified with K0 = 3 (K0 = 3). In this case, if the subcarrier interval of the DL BWP on which the PDCCH is transmitted is the same as the subcarrier interval of the DL BWP on which the PDSCH is scheduled, the terminal can determine that the PDSCH is scheduled in downlink slot n + K0, i.e., slot n + 3.

[0134] The terminal can determine the slot to receive the PDSCH using the K0 value, and determine the symbols to which the PDSCH is transmitted using the index (S) and length (L) values ​​of the starting symbol in the slot that receives the PDSCH. The symbols to which the PDSCH is transmitted may be symbols S through S+L-1 in the slot calculated based on the K0 value. Symbols S through S+L-1 may be L consecutive symbols.

[0135] The terminal may be further configured with respect to the downlink slot aggregation from the base station. In this case, the downlink slot aggregation may have values ​​of 2, 4, or 8. Once configured with respect to the downlink slot aggregation, the terminal can receive PDSCH in a sequence of slots determined by the slot aggregation value, starting from the slot determined based on the K0 value.

[0136] When a terminal receives DCI formats 1_0, 1_1, or 1_2, which are DCIs that schedule a PUCCH, the terminal can transmit the PUCCH scheduled by the DCI to the base station. At this time, the PUCCH may include HARQ-ACK information. The "PDSCH-to-HARQ_feedback timing indicator" field in DCI formats 1_0, 1_1, and 1_2 can indicate a K1 value, which is information about the slot on which the scheduled PUCCH can be transmitted. K1 may be 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 and 1_2 may be configured or set from the upper layer. The HARQ-ACK information may be HARQ-ACK information indicating whether or not the reception of two types of channels was successful. The first type may be HARQ-ACK information indicating whether the terminal successfully received a PDSCH when a PDSCH is scheduled to the terminal by a DCI in DCI format 1_0, 1_1, or 1_2. The second type may be HARQ-ACK information indicating whether the terminal received a DCI instructing the release of an SPS PDSCH when a DCI in DCI format 1_0, 1_1, or 1_2 received by the terminal instructs the release of an SPS PDSCH.

[0137] The terminal can determine the uplink slot on which a PUCCH containing the first type of HARQ-ACK information is transmitted as follows: The terminal can determine the slot on which a PUCCH is transmitted based on the uplink slot on which the HARQ-ACK information and the corresponding PDSCH are transmitted overlap. For example, if the index of the uplink slot is m, the terminal can determine the index of the uplink slot on which a PUCCH containing HARQ-ACK information is transmitted as m+K1. The index of the uplink slot may be a value determined based on the subcarrier interval of the BWP on which the PUCCH is transmitted. When the terminal has set up a downlink slot aggregate, the last symbol on which the PDSCH is transmitted may be the last symbol on which the PDSCH is scheduled in the last slot on which the PDSCH is received.

[0138] Figure 13 shows the scheduling of a physical uplink control channel according to one embodiment of the present invention.

[0139] Referring to Figure 13, the terminal can receive a PDCCH that schedules a PDSCH in downlink slot n. In this case, the DCI included in the PDCCH can indicate a K0 value of 3 and a K1 value of 2. The subcarrier interval of the DL BWP where the PDCCH is received, the subcarrier interval of the DL BWP where the PDSCH is scheduled, and the subcarrier interval of the UL BWP where the PUCCH is transmitted may be the same. In this case, the terminal can receive a PDSCH in downlink slot n+K0, i.e., downlink slot n+3. The terminal can determine the uplink slot that coincides with the last symbol of the PDSCH scheduled in downlink slot n+3. In this case, the last symbol of the PDSCH scheduled in downlink slot n+3 coincides with uplink slot n+3. Therefore, the terminal can transmit a PUCCH containing the first type of HARQ-ACK information on uplink slot n+3+K1, i.e., slot n+5.

[0140] Furthermore, the terminal can determine the slot on which a PUCCH containing the second type of HARQ-ACK information is transmitted as follows: The terminal can determine that the uplink slot on which the second type of HARQ-ACK information is transmitted is the slot on which the second type of HARQ-ACK information is transmitted if it coincides with the last symbol on which the second type of HARQ-ACK information and the corresponding PDCCH are transmitted. When the index of the uplink slot is m, the terminal can transmit a PUCCH containing the second type of HARQ-ACK information on the uplink slot m+K1. In this case, the index of the uplink slot may be determined by the subcarrier interval of the uplink BWP on which the PUCCH is transmitted.

[0141] Figure 14 shows the scheduling of a physical uplink sharing channel and a physical uplink control channel according to one embodiment of the present invention.

[0142] Referring to Figure 14, the terminal can receive a DCI instructing the deactivation of the SPS PDSCH in the downlink slot n. In this case, the DCI can instruct a K1 value of 3. The subcarrier interval of the DL BWP where the PDCCH is received and the subcarrier interval of the UL BWP where the PUCCH is transmitted may be the same. In this case, the terminal can determine the uplink slot that coincides with the last symbol of the PDCCH received in slot n. The terminal can determine that a PUCCH containing HARQ-ACK information of the DCI instructing the deactivation of the SPS PDSCH is scheduled in the uplink slot n+K1, i.e., n+3.

[0143] When a terminal receives a DCI format 0_0, 0_1, or 0_2, which is a DCI for scheduling a PUSCH, the terminal can transmit the scheduled PUSCH to the base station. To do this, the terminal must determine from the DCI the slot in which the PUSCH is scheduled, as well as the starting index and length (number of symbols) of the symbols within that slot. The TDRA (time domain resource assignment) field of DCI formats 0_0, 0_1, and 0_2 can indicate a K2 value, which is information about the slot in which the PUSCH is scheduled, and an SLIV (starting length indicator value), which is a value for information about the index and length of the starting symbols within the slot. Here, K2 may be a non-negative integer value. Here, SLIV may be a joint-encoded value of the index (S) and length (L) of the starting symbols within the slot. Alternatively, SLIV may indicate the index (S) and length (L) of the starting symbols within the slot separately. Here, in a normal CP, S may have one value from 0, 1, ..., 13, and L may have one value from the natural numbers satisfying the condition that S + L is less than or equal to 14. In an extended CP, S may have one value from 0, 1, ..., 11, and L may have one value from the natural numbers satisfying the condition that S + L is less than or equal to 12.

[0144] The terminal can determine which slot PUSCH is transmitted to based on the K2 value. Specifically, the terminal can determine which slot PUSCH is transmitted to based on the K2 value, the index of the slot to which DCI is transmitted, the subcarrier interval of the downlink BWP to which DCI is transmitted, and the subcarrier interval of the uplink BWP to which PUSCH is transmitted.

[0145] For example, if the subcarrier intervals of the downlink BWP on which DCI is transmitted and the uplink BWP on which a scheduled PUSCH is transmitted are the same, and the terminal receives DCI in downlink slot n, the terminal can transmit PUSCH in uplink slot n+K2.

[0146] For example, if the subcarrier interval of the downlink BWP to which DCI is transmitted is 15kHz*2^mu_PDCCH, and the subcarrier interval of the uplink BWP to which a scheduled PUSCH is transmitted is 15kHz*2^mu_PUSCH, then the terminal can receive DCI in downlink slot n. Here, the index of downlink slot n may be determined by the subcarrier interval of the downlink BWP to which DCI is transmitted. In this case, the terminal can transmit PUSCH in 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 may be determined by the subcarrier interval of the uplink BWP to which PUSCH is transmitted. mu_PDCCH and mu_PUSCH may have values ​​of 0, 1, 2, or 3.

[0147] Referring to Figure 14, the terminal can receive a PDCCH that schedules a PUSCH in downlink slot n. The DCI included in the PDCCH can indicate a K2 value of 3. The subcarrier interval of the DL BWP on which the PDCCH is transmitted and the subcarrier interval of the UL BWP on which the PUSCH is transmitted may be the same. In this case, the terminal can determine that a PUSCH is scheduled in uplink slot n+K2, i.e., slot n+3.

[0148] The terminal can determine the slot to send a PUSCH based on the K2 value, and use the index (S) and length (L) of the starting symbol in the determined slot to determine which symbols can be sent a PUSCH. Specifically, the symbols to which a PUSCH is sent may be symbols S to S+L-1 in the slot determined based on the K2 value. Symbols S to S+L-1 may be L consecutive symbols.

[0149] Furthermore, 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 configured for uplink slot aggregation on the terminal, the terminal can transmit PUSCH on consecutive slots corresponding to the slot aggregation value, starting from the slot determined based on the K2 value.

[0150] In Figures 12 to 14, the terminal can use K0, K1, and K2 values ​​to determine the slots to which scheduled PDSCHs are transmitted, PUCCHs are transmitted, and PUSCHs are transmitted. In this specification, the slots determined when such K0, K1, and K2 values ​​are 0 may be the reference point or reference slot. That is, in Figure 12, the reference slot is the downlink slot n, which is the slot to which the PDCCH is received; in Figure 13, the reference slot is the uplink slot n+3, which is the uplink slot to which the last symbol on which the PDSCH is transmitted coincides; and in Figure 14, the reference slot may be the uplink slot n, which is the uplink slot to which the last symbol on which the PDCCH is transmitted coincides.

[0151] In this specification, uplink slots and downlink slots may be referred to simply as slots without being distinguished separately. Hereafter, we assume that the subcarrier interval of the downlink BWP on which PDSCH and PDCCH are transmitted is the same as the subcarrier interval of the uplink BWP on which PUSCH and PUCCH are transmitted.

[0152] To increase the reliability of PDCCH reception, the terminal may be configured to receive PDCCH repeatedly from the base station. The reliability of PDCCH reception can be determined based on the CCE aggregation level (AL) for PDCCH. For example, a terminal may have higher reliability receiving PDCCH at CCE aggregation level 8 or 16 compared to receiving it at CCE aggregation level 1 or 2. In this specification, reception reliability can mean the probability that the terminal will successfully receive PDCCH.

[0153] A base station can set the CCE aggregation level and the number of PDCCH candidates monitored by the terminal per CCE aggregation level, using the control resource set and search space information for the terminal to receive PDCCHs. Terminals in certain situations, such as those located at the cell edge, may require a high CCE aggregation level for PDCCH reception. However, the control resource set that the base station has set for the terminal may not be able to provide the CCE aggregation level required for PDCCH reception. For example, to support CCE aggregation level 16 for PDCCH reception, the terminal's control resource set requires 16 CCEs, i.e., 96 REGs (resource element groups). In this case, if the control resource set has 2 symbols, the control resource set can contain 96 REGs only if at least 48 RBs are allocated on the frequency domain resources. However, if the frequency domain bandwidth supported by the terminal is narrow, or if the base station sets the terminal to use only a narrow bandwidth for channel reception, the control resource set may not be able to support CCE aggregation level 16. In situations where it is difficult to set a high CCE integration level, the base station can configure the terminal to repeatedly receive PDCCH.

[0154] In this specification, PDCCH1A, PDCCH1B, etc., can refer to PDCCHs that a terminal monitors and receives, such as PDCCH#1A candidate, PDCCH#1B candidate, etc. Also, in this specification, (repeated)PDCCH candidate and (repeated)PDCCH may be used interchangeably.

[0155] The following describes a specific method for configuring a base station to repeatedly receive PDCCH signals from a terminal, using Figures 15 to 17.

[0156] Figure 15 shows an embodiment of the present invention in which PDCCH is repeatedly transmitted using different sets of control resources.

[0157] Referring to Figure 15, the terminal can assume that PDCCHs transmitted over multiple sets of different control resources contain the same DCI. Specifically, the terminal can receive PDCCH1A by monitoring with CORESET A in the first slot (slot n in Figure 15), and receive PDCCH1B by monitoring with CORESET B in the second slot (slot n+1 in Figure 15). In this case, the terminal may be pre-configured by the base station to be PDCCH1A and PDCCH1B containing the same DCI. The terminal can obtain DCI information by independently decoding PDCCH1A and PDCCH1B. However, if DCI information is not obtained even after independently decoding PDCCH1A and PDCCH1B, the DCI information can be obtained by combining and decoding PDCCH1A and PDCCH1B. In addition to PDCCH1A and PDCCH1B mentioned above, PDCCH1C can also be received on CORESET C, and PDCCH1D can be received on CORESET D. Furthermore, although Figure 15 explains that the same DCI is included in the PDCCH of CORESETs in different slots (for example, slot n and slot n+1), multiple CORESETs may be set up in a single slot, and a terminal can receive PDCCH on multiple CORESETs, and each received PDCCH may include the same DCI. In other words, the first slot and the second slot may be separate slots or the same slot. Also, in this case, PDCCHs containing the same DCI may have the same CCE integration level.

[0158] Figure 16 shows an embodiment of the present invention in which PDCCH is repeatedly transmitted in different search spaces.

[0159] Referring to Figure 16, a base station can set up multiple search spaces for a single CORESET (CORESET A in Figure 16) for a terminal. That is, although the CORESET is set to the same resource area for each slot, the search space for each slot may be set to a separate time resource area. The terminal can assume that PDCCH transmitted across multiple search spaces contains the same DCI. Since one CORESET is the same resource area for each slot, the frequency domain and time domain length (number of symbols) for which PDCCH is transmitted are the same. The terminal can monitor in search space A of CORESET A in the first slot (slot n in Figure 16) and receive PDCCH1A, and monitor in search space B of CORESET A in the second slot (slot n+1 in Figure 16) and receive PDCCH1B. The base station can pre-configure the terminal that the DCI contained in PDCCH1A and PDCCH1B are the same. The terminal can independently decode PDCCH1A and PDCCH1B to obtain DCI information. However, if DCI information is not obtained despite independent decoding of PDCCH1A and PDCCH1B, the DCI information can be obtained by combining and decoding PDCCH1A and PDCCH1B. In addition to PDCCH1A and PDCCH1B, the terminal can receive PDCCH1C in search space C and PDCCH1D in search space D. Furthermore, although Figure 16 explains that the same DCI is included in PDCCHs transmitted on search spaces of different slots (for example, slot n and slot n+1), multiple search spaces may be set within a single slot, and the terminal can receive PDCCHs on each of these multiple search spaces, and each received PDCCH may also contain the same DCI. In other words, the first slot and the second slot may be different slots or the same slot. Also, in this case, PDCCHs containing the same DCI may have the same CCE integration level.

[0160] For the purposes of this specification, a PDCCH containing the same DCI information may be referred to as a repeating PDCCH. A PDCCH transmitted only once may also be included in a repeating PDCCH. For example, in Figures 15 and 16, the PDCCH is a PDCCH that is repeated four times and may be set as PDCCH1A, PDCCH1B, PDCCH1C, and PDCCH.

[0161] When a terminal is configured by the base station to receive repeating PDCCHs, it can monitor candidate PDCCHs (e.g., candidate PDCCH#1A, candidate PDCCH#1B, candidate PDCCH#1C, candidate PDCCH#1D in Figures 15 and 16) that are configured to be received repeatedly and contain the same DCI information, receive the PDCCH, and determine whether the DCI contained in the received PDCCH was received correctly. The terminal can determine whether one, multiple, or all of the repeating PDCCHs were successfully received. For example, if a PDCCH is configured to be transmitted repeatedly four times, the terminal can monitor only candidate PDCCH#1A and successfully receive the DCI contained in that PDCCH. The terminal can also monitor candidate PDCCH#1B and candidate PDCCH#1C and successfully receive the DCI contained in those PDCCHs. Furthermore, the terminal can monitor candidate PDCCH#1A, candidate PDCCH#1B, candidate PDCCH#1C, and candidate PDCCH#1D and successfully receive the DCI included in the corresponding PDCCH.

[0162] Figure 17 shows an embodiment of the present invention in which different repeating PDCCHs overlap in the time-frequency domain.

[0163] The base station can configure the terminal to monitor the first repeating PDCCH candidate in the first CORESET and search space and to receive the first repeating PDCCH. Similarly, the base station can configure the terminal to monitor the second repeating PDCCH candidate, the third repeating PDCCH candidate, and the fourth repeating PDCCH candidate in the second CORESET and search space, the third CORESET and search space, and the fourth CORESET and search space, respectively, and to receive the second repeating PDCCH, the third repeating PDCCH, and the fourth repeating PDCCH.

[0164] Referring to Figure 17, the terminal can monitor the repeating PDCCH#1 candidate (first repeating PDCCH candidate) on the first CORESET and the search space and receive the first repeating PDCCH. The first repeating PDCCH may be set to be transmitted four times. The PDCCH that is repeated four times may be the PDCCH transmitted on the PDCCH#1A candidate in slot n, the PDCCH#1B candidate in slot n+1, the PDCCH#1C candidate in slot n+2, and the PDCCH#1D in slot n+3. The terminal can monitor the repeating PDCCH#2 candidate (second repeating PDCCH candidate) on the second CORESET and the search space and receive the second repeating PDCCH. The second repeating PDCCH may be set to be transmitted two times. The PDCCH that is repeated twice may be the PDCCH transmitted on the PDCCH#2A candidate in slot n+1 and the PDCCH#2B candidate in slot n+2. The terminal can monitor the repeating PDCCH#3 candidate (third repeating PDCCH candidate) on the third CORESET and the search space and receive the third repeating PDCCH. The third repeating PDCCH may be configured to be received without repetition in slot n+2. In this case, the received PDCCH may include DCI in DCI format having a CRC scrambled with C-RNTI, MCS-C-RNTI, CS-RNTI, SFI-RNTI, INT-RNTI, or CI-RNTI. In this case, the format of the received DCI may include DCI formats 0_0, 0_1, 0_2, 1_0, 1_1, 1_2, 2_0, 2_1, ~2_4.

[0165] Referring to Figure 17, there may be cases where the resources used by a terminal to monitor PDCCHs transmitted in different CORESETs and search spaces configured by the base station overlap. Specifically, the base station can configure the terminal to repeatedly monitor a repeating PDCCH#1 candidate (first repeating PDCCH candidate) in slots n, n+1, n+2, and n+3. The base station can also configure the terminal to repeatedly monitor a repeating PDCCH#2 candidate (second repeating PDCCH candidate) in slots n+1 and n+2. That is, the terminal must monitor repeating PDCCH#1 candidate and repeating PDCCH#2 candidate in slots n+1 and n+2 and receive the corresponding PDCCH. In this case, if the time-frequency resource domains of slots n+1 and n+2, where PDCCH#1 is transmitted, overlap with the resources where PDCCH#2 is transmitted, the terminal cannot distinguish whether the PDCCH received in slots n+1 and n+2 is repeating PDCCH#1 or repeating PDCCH#2 by monitoring. Therefore, even if the terminal successfully receives a repeating PDCCH, a problem may arise when decoding the DCI information contained in the received repeating PDCCH: whether to identify the received PDCCH as repeating PDCCH#1 or repeating PDCCH#2. Moreover, the base station can configure the terminal to monitor repeating PDCCH#3 candidate (third repeating PDCCH candidate) in slot n+2 without repetition and receive the corresponding PDCCH. In this case, the terminal can monitor repeating PDCCH#1 candidate, repeating PDCCH#2 candidate, and PDCCH#3 candidate on slot n+2 and receive the corresponding PDCCH. If the time-frequency resource domains of slot n+2 from which PDCCH#1, PDCCH#2, and PDCCH#3 are transmitted overlap, the terminal cannot distinguish whether the PDCCH received in slot n+2 is repeating PDCCH#1, repeating PDCCH#2, or PDCCH#3. Therefore, even if a terminal successfully receives a repeating PDCCH, it may encounter a problem when decoding the DCI information contained in the received repeating PDCCH: whether to identify the received PDCCH as repeating PDCCH#1, repeating PDCCH#2, or repeating PDCCH#3.The overlap of the time-frequency resource domains described above may include cases where the resource domains on which PDCCHs are transmitted fully overlap. In other words, it may include situations where the CCEs on which each PDCCH is transmitted fully overlap.

[0166] The following section describes the case where it is not possible to determine which iteration PDCCH a terminal belongs to due to the overlap of time-frequency resource domains mentioned above, i.e., PDCCH ambiguity.

[0167] Figure 18 illustrates a problem that occurs when a physical downlink shared channel determines the scheduled slot according to one embodiment of the present invention.

[0168] Figure 18 illustrates the problem with the K0 value described above. Referring to Figure 18(a), if the DCI successfully received by the terminal is included in the first iteration PDCCH (set to be transmitted four times), the terminal can consider slot n+3, where the last iteration PDCCH of the first iteration PDCCH is transmitted, as the reference slot, and apply the K0 value from the reference slot. That is, the terminal can determine that the PDSCH was scheduled to be transmitted in slot n+3 + K0(n+3 + 3), i.e., slot n+6. Referring to Figure 18(b), if the DCI successfully received by the terminal is included in the second iteration PDCCH (set to be transmitted two times), the terminal can consider slot n+2, where the last iteration PDCCH of the second PDCCH is transmitted, as the reference slot, and apply the K0 value from the reference slot. That is, the terminal can determine that the PDSCH was scheduled to be transmitted in slot n+5, which is slot n+2 + K0(n+2 + 3). Therefore, different results can occur depending on which iterative PDCCH the terminal considers to be the one that contains the DCI it successfully received.

[0169] Figure 19 illustrates a problem that occurs when a physical uplink sharing channel and a physical uplink control channel determine the scheduled slot according to one embodiment of the present invention.

[0170] Figure 19 shows the problems related to the K1 and K2 values ​​mentioned above.

[0171] First, the issue of the K1 value will be explained with reference to Figure 19. In Figure 19, the PUCCH can contain HARQ-ACK information for a DCI that instructs the SPS PDSCH to be released. Referring to Figure 19(a), if the DCI successfully received by the terminal is included in the first iteration PDCCH (configured to be sent four times), the terminal can consider slot n+3, where the last iteration PDCCH of the first iteration PDCCH is sent, as the reference slot, and apply the K1 value from the reference slot. That is, the terminal can determine that the PUCCH is scheduled to be sent in slot n+5, which is slot n+3 + K1(n+3+2). Referring to Figure 19(b), if the DCI successfully received by the terminal is included in the second iteration PDCCH (configured to be sent two times), the terminal can consider slot n+2, where the last iteration PDCCH of the second iteration PDCCH is sent, as the reference slot, and apply the K1 value from the reference slot. In other words, the terminal can determine that PUCCH was scheduled to be sent in slot n+4, which is slot n+2+K2(n+2+2). Therefore, different results can occur depending on which iterative PDCCH the terminal considers to be the iterative PDCCH containing the DCI that it successfully received.

[0172] Next, we will explain the issue of the K2 value with reference to Figure 19. Referring to Figure 19(a), if the DCI successfully received by the terminal is included in the first iteration PDCCH (set to be sent four times), the terminal can consider slot n+3, where the last iteration PDCCH of the first PDCCH is sent, as the reference slot, and apply the K2 value from the reference slot. That is, the terminal can determine that PUSCH is scheduled to be sent in slot n+3 + K2(n+3+2), i.e., slot n+5. Referring to Figure 19(b), if the DCI successfully received by the terminal is included in the second iteration PDCCH (set to be sent two times), the terminal can consider slot n+2, where the last iteration PDCCH of the second iteration PDCCH is sent, as the reference slot, and apply the K2 value from the reference slot. That is, the terminal can determine that PUSCH is scheduled to be sent in slot n+4, which is slot n+2 + K2(n+2+2). Therefore, different results can occur depending on which iterative PDCCH the terminal considers to be the one that contains the DCI it successfully received.

[0173] Figure 20 shows that a slot is determined by a dynamic slot format indicator according to one embodiment of the present invention.

[0174] Figure 20 illustrates the problems that occur when applying the slots and symbol configurations (uplink, downlink, flexible) specified by the Dynamic Slot Format Indicator (SFI).

[0175] The DCI in DCI format 2_0 included in the first repeating PDCCH transmitted by the base station may include a dynamic SFI. The terminal can determine the slots and the symbol configuration of the slots based on the dynamic SFI. In this case, the slots indicated by the dynamic SFI may be a specific number of slots starting from the last slot on which the repeating PDCCH is transmitted. In this case, the specific number may be set by the RRC. For example, referring to Figure 20, the base station can configure the terminal to receive the first repeating PDCCH repeatedly in slots n, n+1, n+2, and n+3. The terminal can apply the symbol configuration indicated by the dynamic SFI to four slots starting from slot n+3, which is the last slot on which the first repeating PDCCH is transmitted. In Figure 20, it was explained that the slot configuration instructed by the dynamic SFI is applied starting from the last slot in which the first iteration PDCCH is transmitted. However, the slot configuration instructed by the dynamic SFI may also be applied starting from the first slot in which the first iteration PDCCH is transmitted, or from a number of slots after the first slot that has been set by the upper layer, or from a number of slots after the last slot that has been set by the upper layer.

[0176] Figure 21 illustrates a problem that occurs when a slot is determined by a dynamic slot formatting directive according to one embodiment of the present invention.

[0177] Figure 21 illustrates the problems that arise when the symbol configuration of a slot specified by Dynamic SFI is applied. Referring to Figure 21(a), if a DCI in DCI format 2_0 that has been successfully received is included in the first iteration PDCCH (configured to be transmitted four times), the terminal can apply the symbol configuration specified by Dynamic SFI starting from slot n+3, which is the last slot in the slots to which the first iteration PDCCH is transmitted. Referring to Figure 21(b), if a DCI in DCI format 2_0 that has been successfully received by the terminal is included in the second iteration PDCCH (configured to be transmitted two times), the terminal can apply the symbol configuration specified by Dynamic SFI starting from slot n+2, which is the last slot in the slots to which the second iteration PDCCH is transmitted. Therefore, the slot to which the symbol configuration specified by Dynamic SFI is applied may change depending on which iteration PDCCH the terminal considers to be the iteration PDCCH containing the DCI that has been successfully received.

[0178] Figure 22 shows that, according to one embodiment of the present invention, the slot is determined based on a downlink preemption indicator.

[0179] Figure 22 shows a problem related to time-frequency domain resources indicated by a downlink preemption indicator (DL preemption indication).

[0180] A base station may transmit a DCI in DCI format 2_1, including a downlink preemption indicator, to a terminal in the first iteration PDCCH. The terminal can determine a reference downlink resource to determine the time-frequency domain resource indicated by the downlink preemption indicator. The downlink preemption indicator may indicate some of the time-frequency domain resources of the reference downlink resource.

[0181] The following describes how the terminal determines the reference downlink resource, referring to Figure 22. In this case, the transmission period of the first iterative PDCCH, which includes the downlink preemption indicator, may be 8 slots. Also, for the sake of explanation, the first iterative transmission (transmission of the iterative PDCCH on slots n to n+3 in Figure 22) is referred to as the transmission in the first period, and the second iterative transmission (transmission of the iterative PDCCH on slots n+8 to n+11 in Figure 22) is referred to as the 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.

[0182] Referring to Figure 22(a), when a terminal receives a first iteration PDCCH containing a downlink preemption indicator transmitted in the second cycle, the downlink reference resource for the downlink preemption indicator can include the space from immediately before the first symbol of the first iteration PDCCH in the second cycle (i.e., slot n+7, which is immediately before the first symbol of slot n+8 in Figure 22(a)) to the first symbol of the first iteration PDCCH in the first cycle (the first symbol of slot n in Figure 22(a)) (slots n to slot n+7 in Figure 22(a)). In other words, the downlink reference resource for the downlink preemption indicator can include the P slots or P*N space immediately before the first symbol of the first iteration PDCCH in the second cycle. slot symb It can contain up to 1 symbol. P is the transmission period of the first iteration PDCCH, and P may be 8. slot symb This refers to the number of symbols that make up the slot. As shown in Figure 22(a), the reference downlink resource is a resource that is a certain time interval away from the last slot on which the first iteration PDCCH is sent. This can lead to a problem where rapid transmission of downlink preemption indicators is not possible.

[0183] Referring to FIG. 22(b), when the terminal receives the first iteration PDCCH including the downlink preamble indicator transmitted in the second period, the reference downlink resource of the downlink preamble indicator can include from immediately before the first symbol of the last iteration PDCCH in the first iteration PDCCH 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 iteration PDCCH in the first iteration PDCCH in the first period (the first symbol of slot n+3 in FIG. 22(b)) (slots n+3 to n+10 in FIG. 22(b)). In other words, the reference downlink resource of the downlink preamble indicator can include P slots or P*N slot symb symbols immediately before the first symbol of the last iteration PDCCH in the first iteration PDCCH in the second period. P is the transmission period of the first iteration PDCCH, and P may be 8. N slot symb means the number of symbols constituting a slot. Referring to FIGS. 22(a) and 22(b), the reference downlink resource includes the slot or symbol in which the terminal receives the iterative PDCCH (i.e., slots n to n+3 in FIG. 22(a), slots n+3 and n+8 to n+10 in FIG. 22(b)). When the terminal cannot receive the PDCCH and the PDSCH simultaneously in one symbol, the slot or symbol in which the iterative PDCCH is transmitted may not be included in the reference downlink resource.

[0184] Referring to FIG. 22(c), when the terminal receives the first iteration PDCCH including the downlink preamble indicator transmitted in the second period, the reference downlink resource of the downlink preamble indicator is Q slots or Q*N immediately before the first symbol of the first iteration PDCCH in the first iteration PDCCH in the second period slot symbIt may contain 8 symbols or Q symbols. Q may be the difference between the transmission period of the repeating PDCCH containing the downlink preemption indicator and the number of repeatedly transmitted slots, or a value set by the base station from the upper layer. Referring to Figure 22(c), the transmission period of the repeating PDCCH is 8 slots, and the number of repeatedly transmitted slots is 4, so Q may be 4(8-4). slot symb This refers to the number of symbols contained in the slot. According to Figure 22(c), cases where the reference downlink resource contains a slot or symbol with repeated PDCCH transmissions set, as shown in Figures 22(a) and (b), may be excluded.

[0185] Figure 23 illustrates a problem that occurs when a slot is determined by a downlink preemption indicator according to one embodiment of the present invention.

[0186] The following describes the problems that arise when a terminal determines the time-frequency domain resource indicated by the downlink preemption indicator, referring to Figure 23. For the sake of explanation, we assume that the reference downlink resource is determined as described in Figure 22(a).

[0187] Referring to Figure 23(a), the first iterative PDCCH containing a DCI in DCI format 2_1, which the base station transmits to the terminal, may be configured to be transmitted four times. In this case, as explained in Figure 22(a), the reference downlink resource can include symbols in slots n to n+7. In Figure 23(b), the second iterative PDCCH containing a DCI in DCI format 2_1, which the base station transmits to the terminal, may be configured to be transmitted twice. In this case, the terminal can determine the reference downlink resource based on slot n+9, where the second iteration of the second iterative PDCCH is set to be received. The number of slots or symbols included in the reference downlink resource may be determined based on the transmission period of the second iterative PDCCH. That is, the reference downlink resource can include symbols in slots n+1 to n+8 (see Figure 22(a)). Therefore, a problem may arise in which different reference downlink resources are determined depending on which iterative PDCCH the terminal considers to be the iterative PDCCH containing the DCI that it has successfully received.

[0188] Figure 24 shows a slot determined by an uplink cancellation indicator according to one embodiment of the present invention.

[0189] Referring to Figure 24, the first iteration PDCCH transmitted by the base station to the terminal may include a DCI in DCI format 2_4 that includes an uplink cancellation indication. The terminal can determine a reference uplink resource to determine the time-frequency domain resource indicated by the uplink cancellation indication. The uplink cancellation indication may indicate some of the time-frequency domain resources of the reference uplink resource.

[0190] Referring to FIG. 24, the reference uplink resource may be determined based on the last symbol of the last PDCCH in the first repeated transmission of the first repeated PDCCH including the uplink cancellation indicator (slot n+3 in FIG. 24). Specifically, the reference uplink resource may include Y symbols after Tproc+X symbols from the last symbol. Here, Tproc is a value determined based on the processing time, and X may be a value set by the upper layer. Y may be a value set by the upper layer or determined based on the transmission period of the first repeated PDCCH. Referring to FIG. 24, Tproc=2, X=1, and Y=4 may be used, and at this time, the units of the Tproc, X, and Y values may be in symbol units.

[0191] FIG. 25 shows the problems that occur when determining a slot by the uplink cancellation indicator.

[0192] FIG. 25 shows the problems that occur when the terminal interprets the resources in the time-frequency domain indicated by the uplink cancellation indicator.

[0193] Referring to Figure 25(a), the reference uplink resources may be determined as described in Figure 24 (slots n+7 to n+10). That is, the last symbol of the last PDCCH in which the first iteration transmission of the first iteration PDCCH is set is the symbol in slot n+3. Therefore, the reference uplink resources may be determined to be from the last symbol in slot n+3 to the Y symbol after the Tproc+X symbol. Referring to Figure 25(b), the second iteration PDCCH transmitted by the base station to the terminal may include a DCI in DCI format 2_4 that includes an uplink cancellation indicator (UL cancelation indication). In this case, the second iteration PDCCH may be set to be repeated twice. The terminal can determine the reference uplink resources based on the last symbol of the last iteration PDCCH in the first iteration interval region in which the second iteration PDCCH is set to be transmitted. That is, the last symbol of the last iteration PDCCH in the first iteration interval region of the second iteration PDCCH is the symbol in slot n+2. Therefore, the terminal can determine that the Y symbol is the uplink resource after the last symbol in slot n+2, Tproc+X symbols. Thus, a problem can arise in which different uplink resources are determined depending on which iterative PDCCH the terminal considers to be the iterative PDCCH containing the DCI that it successfully received.

[0194] The following describes a method for resolving the PDCCH ambiguity described above. Specifically, it describes a method for determining which of several different repeating PDCCHs the DCI received by the terminal belongs to. The terminal can also determine which repeating PDCCH the received DCI belongs to and send a HARQ-ACK to the base station for it. That is, the terminal can send a HARQ-ACK to the base station for the PDCCH determined by the method described later. In this case, the HARQ-ACK that the terminal sends to the base station may be the first type of HARQ-ACK and / or the second type of HARQ-ACK described above.

[0195] i) First method

[0196] To distinguish between different repeating PDCCHs, the base station may transmit additional information required for distinguishing between different repeating PDCCHs in the DCI. When a terminal successfully receives a repeating PDCCH, it can determine which repeating PDCCH was successfully received based on the additional information included in the DCI. In this case, the information for distinguishing between different repeating PDCCHs may include at least one of the following:

[0197] DCI can include, as primary information, information about the number of times the repeating PDCCH has been transmitted. That is, DCI can include a value for the number of times the repeating PDCCH has been transmitted.

[0198] For example, if the number of repetitions of the repetitive PDCCH transmitted by the base station to the terminal is 4, the DCI may contain information (values) indicating the number of repetitions (4 times), or it may contain information (values) that allow the number of repetitions to be inferred.

[0199] As another example, if the terminal is configured to receive a first repeating PDCCH four times and a second repeating PDCCH twice, the first and second repeating PDCCHs may completely overlap in the time-frequency domain resources of either slot. In this case, the DCI may include an indicator to distinguish between the first and second repeating PDCCHs. If there are L types of repeating PDCCHs, the DCI can indicate the type of repeating PDCCH using ceil(log2(L)) bits, where ceil(x) is a function that indicates the smallest integer not less than x. Specifically, if there are two types of repeating PDCCHs, a first repeating PDCCH and a second repeating PDCCH, the information that can distinguish between the repeating PDCCHs included in the DCI may be an indicator of size ceil(log2(2)) bits (i.e., 1 bit). A value of "0" in the 1-bit indicator indicates a second repeating PDCCH that is transmitted twice, and a value of "1" indicates a first repeating PDCCH that is transmitted four times. In general, a terminal can determine the number of repeating PDCCHs in any one slot where resources in the time-frequency domain completely overlap. If the number of overlapping repeating PDCCHs is X, the required information may be represented in ceil(log2(X)) bits. Each code point of the ceil(log2(X)) bits can indicate the number of repetitions of the overlapping repeating PDCCHs. For example, the lowest value of the code points can indicate the number of repetitions of the PDCCH with the lowest number of repetitions among the repeating PDCCHs set in the terminal. In this case, the values ​​of the code points can indicate the number of repetitions of the repeating PDCCHs in ascending order.

[0200] The second piece of information included in the DCI may be information (a value) indicating the ID of the CORESET corresponding to the repeating PDCCH. For example, when the first repeating PDCCH is transmitted on the first CORESET and the second repeating PDCCH is transmitted on the second CORESET, the first and second repeating PDCCHs may completely overlap in the time-frequency resource domain on either slot. In this case, the DCI may include an indicator to distinguish between the first and second repeating PDCCHs. Specifically, if there are two types of repeating PDCCHs, the first and second repeating PDCCHs, the DCI may include a 1-bit indicator to distinguish between the first and second repeating PDCCHs. If the value of the 1-bit indicator is "0", it indicates the first repeating PDCCH transmitted on the first CORESET, and if the value of the indicator is "1", it indicates the second repeating PDCCH transmitted on the second CORESET. In general, a terminal can determine the number of CORESETs corresponding to recurring PDCCHs on any one slot where time-frequency domain resources completely overlap. If the number of overlapping recurring PDCCHs is X, the information contained in the DCI may have a size of ceil(log2(X)). Each code point indicated by the ceil(log2(X)) bits can indicate a CORESET ID corresponding to an overlapping recurring PDCCH. For example, the lowest value of a code point can indicate the lowest CORESET ID corresponding to an overlapping recurring PDCCH. The values ​​of the code points can indicate CORESET IDs in ascending order. The CORESET ID is a value set in the upper layer, and the base station can transmit CORESET information, including the CORESET ID, to the terminal.

[0201] The third piece of information included in the DCI may be information (a value) indicating the search space ID corresponding to the repeating PDCCH. For example, when the first repeating PDCCH is transmitted in the first search space and the second repeating PDCCH is transmitted in the second search space, the first and second repeating PDCCHs may completely overlap in the time-frequency resource domain on either slot. In this case, the DCI may include an indicator to distinguish between the first and second repeating PDCCHs. If there are two types of repeating PDCCHs, the first and second repeating PDCCHs, the DCI may include a 1-bit indicator to distinguish between the first and second repeating PDCCHs. Specifically, if the value indicated by the 1-bit indicator is "0", it indicates the first repeating PDCCH corresponding to the first search space, and if the value of the indicator is "1", it indicates the second repeating PDCCH corresponding to the second search space. In general, a terminal can determine the number of search spaces corresponding to repeating PDCCHs on any one slot that completely overlap. If the number of search spaces corresponding to overlapping repeating PDCCHs is X, the information contained in the DCI may have a size of ceil(log2(X)) bits. Each code point indicated by the ceil(log2(X)) bits can indicate a search space ID corresponding to an overlapping repeating PDCCH. For example, the lowest value of a code point can indicate the lowest ID among the search space IDs corresponding to overlapping repeating PDCCHs. The values ​​of the code points can indicate search space IDs in ascending order. The search space ID is a value set from the upper layer, and the base station can transmit search space information, including the search space ID, to the terminal.

[0202] The fourth piece of information included in the DCI may be information (a value) indicating the repeating PDCCH ID corresponding to the repeating PDCCH. For example, when the first repeating PDCCH has the first repeating PDCCH ID and the second repeating PDCCH has the second repeating PDCCH ID, the first and second repeating PDCCHs may completely overlap in the time-frequency resource domain on either slot. In this case, the DCI may include an indicator to distinguish between the first and second repeating PDCCHs. When there are two types of repeating PDCCHs, the first and second repeating PDCCHs, the DCI may include a 1-bit indicator to distinguish between the first and second repeating PDCCHs. Specifically, if the value indicated by the 1-bit indicator is "0", it indicates the first repeating PDCCH having the first repeating PDCCH ID, and if the value of the indicator is "1", it indicates the second repeating PDCCH having the second repeating PDCCH ID. In general, a terminal can determine the number of repeating PDCCH IDs corresponding to repeating PDCCHs where time-frequency domain resources on any one slot completely overlap. If the number of repeating PDCCH IDs corresponding to overlapping repeating PDCCHs is X, the information contained in the DCI may have a size of ceil(log2(X)) bits. Each code point of the ceil(log2(X)) bits can indicate a repeating PDCCH ID corresponding to an overlapping repeating PDCCH. The lowest value of the code points can indicate a repeating PDCCH ID among the IDs of the overlapping repeating PDCCHs. The values ​​of the code points can indicate repeating PDCCH IDs in ascending order. The repeating PDCCH IDs may be values ​​set in higher layers. For example, the number of repeating PDCCH candidates that the terminal monitors per aggregation level and CCE aggregation level may be set based on the search space information transmitted from the base station to the terminal. Also, a unique repeating PDCCH ID may be set for each repeating PDCCH candidate that the terminal monitors. The repeating PDCCH ID may be a value obtained by the terminal based on CORESET information and / or search space information received from the base station.For example, the CCE integration level and the number of repeating PDCCH candidates monitored by the terminal per CCE integration level may be set based on the search space information, and the lowest CCE integration level may be mapped to the lowest repeating PDCCH ID, and the CCE integration levels and repeating PDCCH IDs may be mapped sequentially. If the base station configures the terminal to monitor multiple repeating PDCCH candidates at the same CCE integration level, the repeating PDCCH ID may be determined based on at least one value of the CCE index, REG index, or PRB index to which the repeating PDCCH is mapped. The repeating PDCCH ID corresponds to at least one value of the CCE index, REG index, or PRB index to which the PDCCH is mapped, and may be mapped in ascending order. The repeating PDCCH ID corresponds to the search space ID, and may be mapped in ascending order. In addition, the repeating PDCCH ID corresponds to the CORESET ID, and may be mapped in ascending order.

[0203] The fifth piece of information included in the DCI may be information (a value) indicating the index of the slot or symbol from which the transmission of the repeating PDCCH begins. For example, the first repeating PDCCH may begin transmission from slot n, and the second repeating PDCCH may begin transmission from slot n+1. Since the first repeating PDCCH and the second repeating PDCCH begin transmission from different slots, the fifth piece of information may be the index of the slot from which the transmission of the first repeating PDCCH and the second repeating PDCCH begin. The first repeating PDCCH may begin transmission from symbol m in a specific slot, and the second repeating PDCCH may begin transmission from symbol m+1 in a specific slot. Since the first repeating PDCCH and the second repeating PDCCH begin transmission from different symbols, the fifth piece of information may be the index of the symbol from which the transmission of the first repeating PDCCH and the second repeating PDCCH begins.

[0204] The sixth piece of information included in DCI may be information (a value) indicating the index of the slot or symbol at which the transmission of the repetitive PDCCH ends. For example, the first repetitive PDCCH may start transmission from slot n and end transmission at slot n+3, and the second repetitive PDCCH may start transmission from slot n+1 and end transmission at slot n+2. Since the first and second repetitive PDCCHs end transmission at different slots, the sixth piece of information may be the index of the slot at which the transmissions of the first and second repetitive PDCCHs end. The first repetitive PDCCH may start transmission from symbol m in a specific slot and end transmission at symbol m+3 in a specific slot, and the second repetitive PDCCH may start transmission from symbol m+1 in a specific slot and end transmission at symbol m+2 in a specific slot. Since the first and second repetitive PDCCHs end transmission at different symbols, the sixth piece of information may be the index of the symbol at which the transmissions of the first and second repetitive PDCCHs end.

[0205] The size of the bits indicating the fifth and sixth pieces of information may be restricted, and therefore the index of the slot or symbol indicated by the fifth and sixth pieces of information may be the information (value) after modular arithmetic. For example, if the size of the restricted bits is N bits, the remainder when the slot index is divided by 2^N (slot index mod 2^N) may be included in the DCI. The method for determining N is as follows: When a terminal must distinguish between different repeating PDCCHs, it can determine the number of slots in which the transmission of the different repeating PDCCHs begins. For example, when the first repeating PDCCH begins transmission from slot n, and the second repeating PDCCH begins transmission from slot n+1, and the first and second repeating PDCCHs completely overlap in the time-frequency domain resources on either slot, the terminal can determine that the number of slots (X) in which the repeating PDCCHs begin is 2. In this case, N may be calculated as N = ceil(log2(X)).

[0206] Multiple repetitive PDCCHs, each with different monitoring periods and offsets, can result in overlapping slots. In this case, adding another field to the DCI to resolve the issues arising from the overlapping slots can lead to increased overhead. As mentioned above, repetitive PDCCHs are used when radio channel conditions are poor, such as at cell edge UEs, so increasing the DCI overhead is inefficient. Therefore, the following describes a method to resolve this issue.

[0207] ii) Second method

[0208] The second method relates to a method for obtaining information to distinguish overlapping repeating PDCCHs by reinterpreting one or more fields included in an existing DCI. When a terminal needs to distinguish a successfully received repeating PDCCH from other different repeating PDCCHs, it can distinguish the repeating PDCCHs by reinterpreting one or more fields of the DCI included in the successfully received PDCCH.

[0209] The field used for reinterpretation may be the RV (redundancy version) field. That is, the terminal can obtain from the DCI's RV field the information necessary to distinguish it from other distinct iterative PDCCHs. Specifically, the terminal can distinguish other distinct iterative PDCCHs by assuming the value of the RV field is a specific value (e.g., 0).

[0210] The field used for reinterpretation may be the field that transmits the TPC command. That is, the terminal can obtain from the field that transmits the TPC command the information necessary to distinguish between different iterative PDCCHs. Specifically, the terminal can distinguish between different iterative PDCCHs by assuming that the value of the TPC command field is a specific value (e.g., 0 dB).

[0211] The field used for re-interpretation may be the DAI (downlink assignment index) field. That is, the terminal can obtain the information necessary to distinguish one of the different repeated PDCCHs from the DAI field. Specifically, the terminal can distinguish different repeated PDCCHs by assuming a specific DAI value as a specific value. For example, the terminal does not know the DAI value, so the DAI value can be assumed to be the lowest value or the highest value. Also, the terminal does not know the DAI value, so HARQ-ACK multiplexing by DAI may not be performed.

[0212] It is clear that other fields other than the fields described above may be used to distinguish different repeated PDCCHs. At this time, the fields for distinguishing different repeated PDCCHs may be set from the upper layer. Also, only some bits of the field can be used for re-interpretation, and the remaining bits can be used for existing purposes. At this time, some bits may be MSB (most significant bits).

[0213] iii) Third method

[0214] The third method does not involve adding another field to the DCI or reinterpreting an existing DCI field, as in the first and second methods described above, but rather uses CRC for classification. That is, information for classifying different repeating PDCCHs may be transmitted to the terminal by DCI scrambled with different CRC values. Specifically, the DCI may be scrambled using a specific RNTI value as the CRC depending on the application. The terminal can determine whether or not it has successfully received the DCI based on the RNTI value determined by the DCI's CRC value. Therefore, the base station can generate a separate RNTI (hereinafter referred to as the first RNTI) based on the information for classifying different repeating PDCCHs and the RNTI value, and then use the first RNTI as the CRC for the DCI. The terminal can compare the CRC value of the received DCI with the first RNTI value to determine whether or not it has successfully received the DCI, and obtain information for classifying different repeating PDCCHs. For example, if the information used to distinguish between different repeating PDCCHs is X bits in size, the base station can generate a first RNTI value by performing an XOR (exclusive OR) operation on X bits of the RNTI. In this case, 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 the available first RNTI values. If the information used to distinguish between different repeating PDCCHs is X bits in size, the number of possible combinations for the first RNTI is 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 which first RNTI value matches. If a matching first RNTI value exists, the terminal can confirm that the DCI contains the information corresponding to the first RNTI value, i.e., the information used to distinguish between different repeating PDCCHs.

[0215] iv) Fourth method

[0216] The fourth method is to pre-configure the terminal so that the information used to distinguish between different repeating PDCCHs is a specific value. Specifically, the specific value may be the lowest or highest value set in the terminal among the values ​​that the information used to distinguish between different repeating PDCCHs can represent.

[0217] The information used to distinguish between different repeating PDCCHs may be a value corresponding to the number of times a repeating PDCCH is transmitted. Therefore, if the specific value set on the terminal is the lowest value, the terminal can assume that it has received the repeating PDCCH with the lowest number of transmissions among the different repeating PDCCHs. If the specific value set on the terminal is the highest value, the terminal can assume that it has received the repeating PDCCH with the highest number of transmissions among the different repeating PDCCHs.

[0218] The information used to distinguish between different repeating PDCCHs may be the CORESET ID corresponding to the repeating PDCCH. Therefore, if the specific value set on the terminal is the lowest value, the terminal can assume that the repeating PDCCH was received on the CORESET with the lowest ID among the CORESETs corresponding to different repeating PDCCHs. If the specific value set on the terminal is the highest value, the terminal can assume that the repeating PDCCH was received on the CORESET with the highest ID among the CORESETs corresponding to different repeating PDCCHs.

[0219] The information used to distinguish between different iterative PDCCHs may be the search space ID corresponding to the iterative PDCCH. Therefore, if the specific value set on the terminal is the lowest value, the terminal can assume that the iterative PDCCH was received in the search space of the lowest ID among the search space IDs corresponding to different iterative PDCCHs. If the specific value set on the terminal is the highest value, the terminal can assume that the iterative PDCCH was received in the search space of the highest ID among the search space IDs corresponding to different iterative PDCCHs.

[0220] The information used to distinguish between different repeating PDCCHs may be the repeating PDCCH ID corresponding to the repeating PDCCH. Therefore, if the specific value set on the terminal is the lowest value, the terminal can assume that it has received the repeating PDCCH with the lowest ID among the repeating PDCCH IDs corresponding to different repeating PDCCHs. If the specific value set on the terminal is the highest value, the terminal can assume that it has received the repeating PDCCH with the highest ID among the repeating PDCCH IDs corresponding to different repeating PDCCHs.

[0221] v) Fifth method

[0222] The fifth method is a method by which the terminal distinguishes between different repeating PDCCHs using the search space type (type). Specifically, the first repeating PDCCH corresponds to the first search space of the first type, the second repeating PDCCH corresponds to the second search space of the second type, and the first and second types may be different from each other. In this case, the terminal can determine that the repeating PDCCH was received in either the first search type space or the second search space. The terminal can determine which of the two search spaces is 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 can determine that the repeating PDCCH was received in the first search space of the cell-common search space type.

[0223] A repeating PDCCH transmitted over the cell common search space may include system information and paging information, and can schedule PDSCH, PUCCH, and PUSCH. Furthermore, a repeating PDCCH transmitted over the cell common search space may include dynamic SFI, downlink preemption indicators, and uplink cancellation indicators that can be transmitted to a specific terminal or group of terminals. Therefore, a repeating PDCCH transmitted over the cell common search space may take precedence over a repeating PDCCH transmitted over a specific terminal search space. Also, since a repeating PDCCH transmitted over the cell common search space can be received by multiple terminals within a cell, if multiple terminals interpret the DCI assuming the received repeating PDCCH is a terminal-specific search space, different actions may be performed for each terminal. Therefore, to prevent multiple terminals from performing different actions, a repeating PDCCH transmitted over the cell common search space may take precedence.

[0224] The first to fifth methods described above describe how a terminal can determine which of the different iterative PDCCHs a received DCI belongs to. Below, we describe a method for resolving PDCCH ambiguity without the terminal determining which iterative PDCCH the received DCI belongs to, and without the terminal determining whether the DCI was transmitted in the exact iterative PDCCH. Specifically, we describe how the timing (i.e., the reference slot) for applying the aforementioned K0, K1, and K2 values ​​is determined explicitly or implicitly, as shown in Figures 18 to 20.

[0225] vi) Sixth method

[0226] The sixth method is a method by which a base station uses DCI to indicate the index of a slot or symbol to which the K0, K1, and K2 values ​​are applied. For example, if the index of a slot or symbol to which the K0, K1, and K2 values ​​are applied is n, the base station can include information for n in the DCI and transmit it to the terminal. If the information for the index of a slot or symbol to which the K0, K1, and K2 values ​​are applied has a size of N bits, the information for n may be included in the DCI as a value obtained by modular arithmetic. Specifically, the information for n may be the remainder (n mod 2^N) obtained by dividing the index n by 2^N in the DCI.

[0227] The method by which a terminal determines the reference slot or symbol index to which the K0, K1, and K2 values ​​should be applied, based on the information contained in the DCI, is as follows: A repeating PDCCH that the terminal has successfully received may be set to be transmitted in slot a, slot a+1, ..., slot a+b-1, where a is a non-negative integer and b is a greater than 0 integer. The terminal can assume that PDSCH, PUCCH, and PUSCH cannot be scheduled before the time when the last part of the repeating PDCCH is received. That is, the terminal can assume that PDSCH, PUCCH, and PUSCH cannot be scheduled before slot a+b-1, which is the last slot among the slots set to transmit the repeating PDCCH. Therefore, the terminal can assume that the time (reference slot) to which the K0, K1, and K2 values ​​should be applied is not a slot prior to slot a+b-1.

[0228] The DCI transmitted by the base station to the terminal may include a specific value, which allows the terminal to determine when a slot can become a reference slot. For example, if the specific value is c, the terminal can determine that slots n+0*2^N+c, n+1*2^N+c, n+2*2^N+c, ..., and n+i*2^N+c are candidates for reference slots to which K0, K1, and K2 values ​​may be applied. Here, c may be one of the values ​​0, 1, ..., 2^N-1. In this case, N may be the bit size of the information indicating the specific value c. The method for selecting one of the multiple candidate reference slots is as follows: As described above, slots before slot a+b-1 cannot become reference slots, and therefore the terminal can determine that any of the slots after slot a+b-1 is a reference slot. For example, among the candidate reference slots, the first slot after slot a+b-1 is determined to be a reference slot.

[0229] The method for determining the reference slot will be explained in detail below, with reference to Figure 26.

[0230] Figure 26 shows a method for determining a reference slot according to one embodiment of the present invention.

[0231] Referring to Figure 26(a), N is 2 bits, and the terminal is instructed by the DCI to be a specific value c, in which case the value of c may be 0. Therefore, the terminal can determine that the possible slot candidates for the reference slot are slot n, slot n+4, slot n+8, ... At this time, since the terminal has received the DCI included in the repeating PDCCH transmitted on slots n+1 and slot n+2, it can determine that slot n+4, which is the first slot among the candidate slots including slots n+1 and slot n+2, is the reference slot. Then, the terminal can apply the K0, K1, and K2 values ​​based on the determined reference slot.

[0232] Referring to Figure 26(b), N is 3 bits, and the terminal is instructed by the DCI to have a specific value c, which may be 0. Therefore, the terminal can determine that the possible slot candidates for the reference slot are slot n, slot n+8, slot n+16, ... At this point, since the terminal has received the DCI included in the repeating PDCCH transmitted on slots n+1 and n+2, it can determine that slot n+8, which is the first slot among the candidate slots including slots n+1 and n+2, is the reference slot. Then, the terminal can apply the K0, K1, and K2 values ​​based on the determined reference slot.

[0233] The terminal determined the reference slot candidates based on specific values ​​included in the DCI. However, including information about specific values ​​in the DCI has the problem of high overhead. To solve this problem, it is not necessary to include information about other specific values ​​in the DCI. For example, the terminal can determine that slot 0*M+c, slot 1*M+c, slot 2*M+c, ..., slot i*M+c, ... are reference slot candidates. In this case, the values ​​M and c set in the higher layer may be non-negative integer values, and in particular, c may be 0.

[0234] vii) Seventh method

[0235] When a terminal must determine whether a successfully received repeating PDCCH is the first or second repeating PDCCH, the terminal can determine that the last slot of the later-ending repeating PDCCH is a reference slot to which the K0, K1, and K2 values ​​can be applied. The terminal can determine that the slot configured to transmit the last PDCCH among the overlapping repeating PDCCHs in the time-frequency resource domain is a reference slot. In this case, since the repeating PDCCH is transmitted repeatedly according to the transmission period, the last PDCCH can mean the last PDCCH among the repeating PDCCHs within one period. This will be explained in detail below with reference to Figure 27.

[0236] Figure 27 shows a method for determining a reference slot according to one embodiment of the present invention.

[0237] Referring to Figure 27, the terminal can determine the last slot on which the first iterative PDCCH is transmitted and the last slot on which the second iterative PDCCH is transmitted from the CORESET information and search space information set by the base station. The first iterative PDCCH may be set to be transmitted in slots n, n+1, n+2, and n+3 within one cycle. The second iterative PDCCH may be set to be transmitted in slots n+1 and n+2 within one cycle. The terminal can determine the later-ending slot among the slots on which the first iterative PDCCH is transmitted and the slots on which the second iterative PDCCH is transmitted to be the reference slot. For example, the first iterative PDCCH is transmitted last in slot n+3 within one cycle, and the second iterative PDCCH is transmitted last in slot n+2 within one cycle. Therefore, the terminal can determine the reference slot based on slot n+3.

[0238] The sixth and seventh methods described above are applicable to the PDCCH ambiguity explained in Figures 20 to 25. For example, when determining the slot to which dynamic SFI is applied or when determining the reference uplink resource, the terminal needs the location information of the slot or symbol to which the last PDCCH of an iterative PDCCH containing a successfully received DCI is transmitted. In this case, the location of the slot or symbol to which the last PDCCH is transmitted may be determined using a method similar to the sixth or seventh method described above.

[0239] Specifically, by the sixth method, the terminal can determine a candidate slot or symbol set having a fixed period. Such a candidate slot or symbol set may be indicated by DCI or determined at a higher layer. The terminal can determine one slot or symbol from the candidate slot or symbol set having a fixed period, based on the last slot or symbol to which the repetitive PDCCH is transmitted. For example, the terminal can select the first candidate slot or symbol from the candidate slot or symbol set that includes the last slot or symbol to which the repetitive PDCCH is transmitted. For example, the terminal can select the first slot or symbol from the candidate slot or symbol set that is after the last slot or symbol to which the repetitive PDCCH is transmitted. From the selected slot or symbol, the terminal can determine the slot or reference uplink resource to which dynamic SFI is applied.

[0240] By the seventh method, the terminal can determine the index of the last slot or symbol to which the first iteration PDCCH is transmitted and the index of the last slot or symbol to which the second iteration PDCCH is transmitted. Of the last slot / symbol to which the first iteration PDCCH is transmitted and the last slot / symbol to which the second iteration PDCCH is transmitted, the slot or uplink resource to which dynamic SFI is applied may be determined based on the later slot / symbol. As yet another example, of the last slot / symbol to which the first iteration PDCCH is transmitted and the last slot / symbol to which the second iteration PDCCH is transmitted, the slot or uplink resource to which dynamic SFI is applied may be determined based on the earliest slot / symbol.

[0241] To determine the reference downlink resource, the terminal needs the location information of the slot or symbol from which the first PDCCH of the iterative PDCCH containing the successfully received DCI is transmitted. The location of the slot or symbol from which the first PDCCH is transmitted may be determined by a method similar to the sixth or seventh method described above.

[0242] Specifically, similar to the sixth method, the terminal can determine a candidate slot or symbol set having a fixed period. The candidate slots and symbol sets may be indicated by DCI or determined from higher layers. The terminal can select one slot or set from the candidate slots or symbol set based on the first slot or symbol from which the repetitive PDCCH is transmitted. For example, the terminal can select the last slot or symbol from the candidate slots or symbol set that precedes the first slot or symbol from which the repetitive PDCCH is transmitted. Alternatively, the terminal can select a slot or symbol from the candidate slots or symbol set that precedes the first slot or symbol from which the repetitive PDCCH is transmitted. The terminal can determine the reference downlink resource based on the selected slot or symbol.

[0243] Similar to the seventh method, the terminal can determine the index of the first slot or symbol to which the first iteration PDCCH is transmitted and the index of the first slot or symbol to which the second iteration PDCCH is transmitted. In this case, the reference downlink resource may be determined based on the first slot / symbol to which the first iteration PDCCH is transmitted and the first slot / symbol to which the second iteration PDCCH is transmitted. As yet another example, the reference downlink resource may be determined based on the last slot / symbol to which the first iteration PDCCH is transmitted and the first slot / symbol to which the second iteration PDCCH is transmitted.

[0244] viii) Eighth method

[0245] The eighth method is a method for transmitting information about the repeated transmission of a repeated PDCCH via a specific PDCCH that sets up a repeated PDCCH.

[0246] When a terminal is configured to receive repetitive PDCCHs from a base station, it can monitor and receive specific PDCCHs and explicitly receive information about the repeated transmission of a repetitive PDCCH. This information about the repeated transmission of a PDCCH may include the first slot (or symbol) in which the transmission of the repetitive PDCCH begins and the number of slots (or symbols) that are repeatedly transmitted.

[0247] A DCI contained in a particular PDCCH may explicitly include information regarding the repeated transmission of a repeating PDCCH. In this case, the particular PDCCH may be referred to as an activation PDCCH, and for convenience of explanation, it will be referred to as a first activation PDCCH in this specification.

[0248] The DCI contained in the first PDCCH in which the transmission of the repeating PDCCH begins may explicitly include information regarding the repeated transmission of the repeating PDCCH. In this case, the first PDCCH may be referred to as the activation PDCCH, and for convenience of explanation, it will be referred to as the second activation PDCCH in this specification.

[0249] The DCIs included in the first PDCCH that initiates the transmission of a repeating PDCCH, and in a specific number of repeating PDCCHs, may explicitly contain information about the repeated transmission of the repeating PDCCH. In this case, the first PDCCH and the specific number of repeating PDCCHs may be referred to as activation repeating PDCCHs. The first PDCCH and the specific number of repeating PDCCHs may be consecutive repeating PDCCHs.

[0250] The terminal can reinterpret existing fields that make up the DCI to obtain information about the repeated transmission of the repeated PDCCH described above. At this time, the DCI can schedule PDSCH, PUCCH, and PUSCH. Existing fields may include the TDRA field. For example, the SLIV value indicated by the TDRA field may be reinterpreted. By reinterpreting the SLIV value, the terminal can obtain resource information for repeated PDCCHs that are repeatedly transmitted after the first active PDCCH, the second active PDCCH, and the active repeated PDCCH.

[0251] Specifically, the TDRA field of the DCI included in the repeating PDCCH that is repeatedly transmitted after the first active PDCCH, second active PDCCH, and active repeating PDCCH may include SLIV values ​​for scheduling PDSCH, PUCCH, and PUSCH. That is, the terminal can obtain resource information for the repeating PDCCH and resource information for PDSCH, PUCCH, and PUSCH based on the TDRA field of the DCI included in the repeating PDCCH that is repeatedly transmitted after the first active PDCCH, second active PDCCH, and active repeating PDCCH. The TDRA fields described herein are shown in Table 4.

[0252] [Table 4]

[0253] Figure 28 shows the reception of active PDCCH and repeated PDCCH according to one embodiment of the present invention.

[0254] Referring to Figure 28, when a terminal receives an active PDCCH#1 in slot n, the terminal can expect PDSCH, PUCCH, and PUSCH transmissions in slot n+5. The terminal can also expect repeated transmissions of repeating PDCCH between slots n+1 and n+3. 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 the PDSCH, PUCCH, and PUSCH transmissions expected in slot n+5.

[0255] When the search spaces for other 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 up for the terminal by receiving information about the repeated transmission of the repeated PDCCH.

[0256] The base station can transmit information about the CORESET and information about the search space to the terminal. The 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.

[0257] The first piece of information regarding the CORESET may be the index of the PRB or PRB set that constitutes the CORESET from which the PDCCH is transmitted. The PRB set may consist of six consecutive PRBs. The index of the PRB or PRB set 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 does not have to correspond to the CORESET for receiving the PDCCH. The second piece of information regarding the CORESET may be the number of symbols from 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 can determine which resource the PDCCH is transmitted to.

[0258] Specifically, the first piece of information regarding CORESET is that the PRB index can be set to 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 can set the indices of P PRBs to PRB#0, PRB#1, ..., PRB#(P-1), where P may be a multiple of 6. In this case, the PRBs may be consecutive or not consecutive in the frequency domain. The second piece of information regarding CORESET is the number of symbols (S) to which PDCCH is transmitted, where S may be one of 1, 2, or 3. That is, a terminal may be configured to receive PDCCH from the base station based on the first and second pieces of information.

[0259] Resources corresponding to the P PRBs and S symbols that make up a CORESET may be configured as REGs (resource element groups). One REG may consist of one PRB and one symbol. That is, P PRBs and S symbols may be configured as P*S REGs. Two, three, or six adjacent REGs may be bundled together to form one REG bundle. The method of bundling two, three, or six REGs may be determined by the length of the CORESET (number of symbols) and the mapping method (interleaved mapping / non-interleaved mapping).

[0260] In a non-interleaved mapping scheme, if the CORESET length is 1 symbol, one REG bundle may be generated by bundling 6 consecutive REGs in the frequency domain. In a non-interleaved mapping scheme, if the CORESET length is 2 symbols, one REG bundle may be generated by bundling 3 REGs in each symbol, resulting in a total of 6 bundles (3 REGs per symbol * 2 symbols). For convenience, when we refer to each of the 2 symbols as symbol A and symbol B, the 3 REGs in symbol A may be consecutive in the frequency domain, and the 3 REGs in symbol B may be consecutive in the frequency domain. Also, the 3 REGs in symbol A and the 3 REGs in symbol B may be located in the same frequency domain. In a non-interleaved mapping scheme, if the CORESET length is 3 symbols, one REG bundle may be generated by bundling 2 REGs in each symbol, resulting in a total of 6 bundles (2 REGs per symbol * 3 symbols). For convenience, when we refer to each of the three symbols that make up the length of CORESET as C symbol, D symbol, and E symbol, the two REGs in C symbol may be consecutive in the frequency domain, the two REGs in D symbol may be consecutive in the frequency domain, and the two REGs in E symbol may be consecutive to each other in the frequency domain. Furthermore, the two REGs in C symbol, the two REGs in D symbol, and the two REGs in E symbol may be located in the same frequency domain.

[0261] In an interleaved mapping scheme, if the CORESET length is 1 symbol, i) a REG bundle may be generated by bundling 6 consecutive REGs in the frequency domain. ii) A REG bundle may be generated by bundling 2 consecutive REGs in the frequency domain. In an interleaved mapping scheme, if the CORESET length is 2 symbols, a REG bundle may be generated by bundling 1 REG from each symbol. In this case, 1 REG from each symbol may be located in the same frequency domain. In an interleaved mapping scheme, if the CORESET length is 3 symbols, a REG bundle may be generated by bundling 1 REG from each symbol. In this case, 1 REG from each symbol may be located in the same frequency domain.

[0262] The CCE may be generated by bundling the REG bundles generated in the manner described above. In this case, the CCE may consist of 6 REGs. That is, since the generated REG bundles consist of 2, 3, or 6 REGs, the CCE may consist of 3, 2, or 1 REG bundle. In the case of non-interleaved mapping, the REG bundle consists of 6 REGs regardless of the length of the CORESET. In this case, the CCE may consist of 1 REG bundle.

[0263] In this specification, we propose a new CORESET that differs from existing CORESETs. The new CORESET may consist of at least one of the following: a different REG, a REG bundle, or a CCE. The method for configuring the new CORESET is described below.

[0264] i) Method A

[0265] A new CORESET may consist of at least six consecutive symbols. The base station can transmit information about the CORESET to the terminal, allowing it to configure a CORESET containing six consecutive symbols. This information may include the starting symbol and symbol length (number) for configuring the new CORESET. Based on the CORESET containing six symbols configured by the base station, the terminal can determine the REG, REG bundle, and CCE structure. For convenience of explanation, the six consecutive symbols will be referred to as symbol #0, symbol #1, symbol #2, symbol #3, symbol #4, and symbol #5.

[0266] Figure 29 shows the configuration of a control resource set according to one embodiment of the present invention.

[0267] Referring to Figure 29, the REG, REG bundle, and CCE may be configured as follows.

[0268] i) A REG may consist of 12 REs included in one PRB for each of the 6 symbols. ii) A REG bundle may contain 6 REGs for 6 symbols. That is, a REG bundle may consist of a REG corresponding to symbol #0, a REG corresponding to symbol #1, ..., a REG corresponding to symbol #5. Since one REG consists of 12 REs, one REG bundle consisting of 6 REGs may consist of 72 REs. iii) A CCE may consist of one REG bundle. Referring to Figure 29, the number of REGs constituting a REG bundle is the same as the number of symbols constituting a CORESET. However, if a CCE is configured as in Figure 29, each REG bundle constituting the CCE is located in the same PRB, and therefore the terminal cannot obtain frequency diversity. Consequently, there is a problem that the PDCCH reception performance deteriorates when a terminal monitors a single CCE.

[0269] Figure 30 shows the configuration of a control resource set according to one embodiment of the present invention.

[0270] Referring to Figure 30, the REG, REG bundle, and CCE may be configured as follows.

[0271] i) A REG may consist of 12 REs contained in one PRB for each symbol. ii) A REG bundle may consist of S REGs corresponding to S consecutive symbols. The method for determining S consecutive symbols will be described later. A single REG bundle may consist of REs contained in S symbols of one PRB (i.e., 12*S REs). In this case, the S value may be one of 1, 2, or 3, and may be a value set in a higher layer. Six consecutive symbols that make up a CORESET may be divided into 6 / S symbol sets. In this case, each symbol set may contain S consecutive symbols. For example, among the 6 / S symbol sets, the first symbol set may contain symbol #0, symbol #1, ..., symbol #(S-1), the second symbol set may contain symbol #S, symbol #(S+1), ..., symbol #(2*S-1), and so on. Subsequent symbol sets may also contain S symbols in sequence. iii) A CCE may consist of 6 / S REG bundles. In this case, the CCE may consist of one REG bundle selected from each symbol set. The index of the REG bundle may be set separately for each symbol set. The terminal can then configure the CCE by selecting REG bundles with the same index from each symbol set. The indices of the REG bundles in each symbol set may be interleaved. On the other hand, an index may be set for all REG bundles that make up the CORESET. The CCE may consist of 6 / S consecutive REG bundles from the set indices. That is, CCE x may consist of REG bundle #(6 / S*x), REG bundle #(6 / S*x+1), and REG bundle #(6 / S*x+6 / S-1). The method for setting the index of the REG bundle is as follows: The REG bundles may be indexed starting from the symbol that is temporally first among the six symbols that make up the CORESET.The REG bundles constituting the PRBs that make up CORESET, located in the lowest frequency domain, may be indexed relative to the time domain, and the REG bundles contained in the next lowest frequency domain may be indexed in the time domain. In this case, the indexed indices may be interleaved.

[0272] ii) Method B

[0273] A new coreset may consist of multiple base coresets. A base coreset may consist of 1 to 3 consecutive symbols. That is, a base station can transmit information about a new coreset to a terminal, and this information may include information about the number of base coresets that make up the new coreset and information about the number of symbols (1 to 3 consecutive symbols) that make up the base coresets.

[0274] Figure 31 shows a control resource set composed of a basic control resource set according to one embodiment of the present invention.

[0275] Referring to Figure 31, the four base CORESETs (base CORESET #0, #1, #2, #3) may each consist of two symbols. A new CORESET may consist of four base CORESETs. Figure 31 shows that the four base CORESETs are composed of the same length (number of symbols) and the same frequency band, but each base CORESET may consist of different lengths and frequency bands. Also, each base CORESET is located contiguously on the time-domain resource, but is not limited to this and may be discontinuous.

[0276] The following describes how to determine multiple base core sets and how to arrange the symbols that make up these multiple base core sets.

[0277] The symbols that make up multiple base CORESETs may be consecutive in the time domain. On the other hand, a terminal can receive the start symbol indices of multiple base CORESETs from a base station. For example, a terminal can receive a 14-bit bitmap. In this case, the MSB of the bitmap can indicate the first symbol in the slot as the start symbol index, and the LSB of the bitmap can indicate the last symbol in the slot as the index of the start symbol.

[0278] Figure 32 shows a control resource set consisting of a basic control resource set according to one embodiment of the present invention.

[0279] Referring to Figure 32, a 14-bit bitmap may be [10010000101000]. In this case, the indices of the symbols corresponding to 1 in the bitmap may be 0, 3, 8, and 10. Therefore, the basic control resource set may be configured to start with symbols 0, 3, 8, and 10.

[0280] The terminal can receive a 14*N bit bitmap from the base station. The bitmap can indicate the starting symbol indices for N slots. Specifically, the bitmap may be divided into 14-bit bundles, in which case the MSB of each 14-bit bundle can indicate the starting symbol index of the first symbol in the slot, and the LSB can indicate the starting symbol index of the last symbol in the slot.

[0281] Figure 33 shows a method for designing a control resource set using a basic control resource set according to one embodiment of the present invention.

[0282] Referring to Figure 33, the base station can transmit a bitmap of length 28 to the terminal. In this case, the first 14 bits indicate the position of the starting symbol of the basic CORESET in the first slot, and the next 14 bits indicate the position of the starting symbol of the basic CORESET in the second slot. Since the first 14 bits are [10010000000000], the basic CORESET may be constructed starting from symbols 0 and 3 in the first slot. Since the next 14 bits are [10100000000000], the basic CORESET may be constructed starting from symbols 0 and 2 in the second slot.

[0283] Each of the multiple base coresets may consist of different symbol lengths (numbers). The base station can transmit to the terminal the position and length of the starting symbol that constitutes the base coreset within a single slot. In this case, the position and length of the starting symbol may be set in pairs. Furthermore, the frequency domains of all of the multiple base coresets may be the same.

[0284] Figure 34 shows a method for constructing a control resource set using a basic control resource set according to one embodiment of the present invention.

[0285] On the other hand, the frequency domains of multiple base CORESETs may differ from one another. Referring to Figure 34, a new CORESET may consist of four base CORESETs. In this case, the multiple base CORESETs may consist of resources in different frequency domains. For example, the first base CORESET (base CORESET#0) may consist of the remaining PRBs excluding the six lowest PRBs in the frequency domain. The second base CORESET (base CORESET#1) may consist 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 consist of the remaining PRBs excluding the six intermediate PRBs. In this way, since each base CORESET consists of resources in different frequency domains from one another, it is advantageous in terms of frequency diversity.

[0286] The following describes how to configure each of the basic coresets when each coreset consists of resources in different frequency domains.

[0287] Base stations can configure the frequency resources of each base coreset using different bitmaps. For example, there may be a bitmap corresponding to each of multiple base coresets, and each bitmap can indicate whether or not a bundle of six PRBs constitutes the base coreset. In this case, the number of PRBs constituting each base coreset may be the same.

[0288] A base station can configure resources in the frequency domain using two distinct bitmaps. The odd-numbered resources in the frequency domain of a base CORESET can be indicated by the first bitmap, and the even-numbered resources in the frequency domain of a base CORESET can be indicated by the second bitmap. Generalizing this, a base station can instruct a terminal on the resources in the frequency domain of a base CORESET using B distinct bitmaps. In this case, if n mod B is 0, the resources in the frequency domain of base CORESET n are indicated by the first bitmap; if n mod B is 1, the resources in the frequency domain of base CORESET n are indicated by the second bitmap. In other words, if n mod B is k, the resources in the frequency domain of a base CORESET may be indicated by the (k+1)th bit of the bitmap. Here, n is the index of the base CORESET, and indexing may start from 0.

[0289] The base station can transmit PRB offset values ​​between base coresets to the terminal. For example, the frequency domain resources of an odd-numbered base coreset among multiple base coresets may be indicated by a bitmap. In this case, the bitmap can indicate whether or not a bundle of 6 PRBs is included in the odd-numbered base coreset. In addition, the base station can transmit PRB offsets to the terminal. The PRB offsets may be in units of 6 PRBs. The PRBs included in an even-numbered base coreset may correspond to the index value obtained by adding the PRB offset to the index of the PRB included in the odd-numbered base coreset.

[0290] Once the base station sets up a new CORESET on the terminal, the terminal can receive PDCCH on each base CORESET. The following describes how the terminal receives PDCCH.

[0291] The index of the CCEs in a base CORESET may be indexed in a frequency-first order. That is, among the base CORESETs that make up a new CORESET, the CCEs included in the earliest base CORESET in the time domain are selected first, and the selected CCEs may be indexed in ascending order in the frequency resource domain. In this case, if the number of first CCEs included in the earliest base CORESET in the time domain is N_CCE0, then each of the first CCEs may be indexed in ascending order in the frequency domain as 0, 1, ..., N_CCE0-1. The second CCEs included in the second earliest base CORESET in the time domain may be indexed in ascending order in the frequency domain. The index of the second CCE may be indexed with values ​​after the last index of the first CCE in the time domain. If the number of CCEs included in the second CCE is N_CCE1, then each of the second CCEs may be indexed in ascending order in the frequency domain as N_CCE0, N_CCE0+1, ..., N_CCE0+N_CCE1-1. In a similar manner, the CCEs of the base CORESET that constitute the new CORESET may be indexed.

[0292] On the other hand, the CCEs of each base CORESET that make up the new CORESET may be indexed in a time-first order. For example, among the base CORESETs that make up the new CORESET, the CCEs that make up the PRB in the lowest frequency domain are selected first, and the selected CCEs may be indexed in ascending order in the time domain. In this case, if the number of first CCEs that make up the PRB in the lowest frequency domain is N_CCE0, then each of the first CCEs may be indexed in ascending order in the time domain as 0, 1, ..., N_CCE0-1. The second CCEs that make up the second lowest PRB in the frequency domain may be indexed in ascending order in the time domain. The index of the second CCE may be indexed with the value after the last index of the first CCE in the frequency domain. If the number of second CCEs is N_CCE1, then each of the second CCEs may be indexed in ascending order in the time domain as N_CCE0, N_CCE0+1, ..., N_CCE0+N_CCE1-1. In a similar manner, the CCEs of the underlying CORESETs that constitute the new CORESET may be indexed.

[0293] Figure 35 shows a method for indexing CCE using a frequency-priority method according to one embodiment of the present invention.

[0294] Referring to Figure 35, each base CORESET constituting the new CORESET may contain eight CCEs. In this case, the CCEs corresponding to the first base CORESET (base CORESET#0) located at symbol 0 and symbol 1 may be indexed as 0, 1, 2, 3, 4, 5, 6, and 7 in a frequency-first order. The CCEs corresponding to the second base CORESET (base CORESET#1) located at symbol 2 and symbol 3 may be indexed as 8, 9, 10, 11, 12, 13, 14, and 15 in a frequency-first order. The CCEs of the remaining base CORESETs constituting the new CORESET may be indexed in the same manner.

[0295] Figure 36 shows a method for indexing CCE using a time-priority method according to one embodiment of the present invention.

[0296] Referring to Figure 36, each PRB included in the new CORESET may consist of four CCEs. In this case, the CCEs in the lowest frequency domain may be indexed 0, 1, 2, and 3 in a time-priority scheme. The CCEs in the second lowest frequency domain may be indexed 4, 5, 6, and 7 in a time-priority scheme. The CCEs of the remaining base CORESETs that make up the new CORESET may be indexed in the same manner.

[0297] The terminal can receive a PDCCH at aggregate level L using L CCEs from among the CCEs that make up the base CORESET. In this case, i) L may be a power of 2. For example, L may be a value such as 1, 2, 4, 8, 16, or 32. Also, ii) L may be a value of 2^k*C, where k is a natural number and C is the number of base CORESETs, which may also be a natural number. For example, if a new CORESET consists of 3 base CORESETs, L may have values ​​such as 1*3, 2*3, 4*3, 8*3, 16*3, or 32*3.

[0298] Figure 37 shows a PDCCH candidate based on a frequency-priority indexed CCE according to one embodiment of the present invention, and Figure 38 shows a PDCCH candidate based on a time-priority indexed CCE according to one embodiment of the present invention.

[0299] Referring to Figure 37, the CCEs constituting the new CORESET may be indexed in a frequency-priority manner. In this case, the area in which the terminal monitors PDCCH candidates may be CCE12 to CCE23 (12 CCEs). Based on the CCE index, the terminal can recognize that the CCEs to be monitored for PDCCH candidates are the four CCEs included in the second base CORESET (base CORESET#1) and all the CCEs included in the third base CORESET (base CORESET#2).

[0300] Referring to Figure 38, the CCEs constituting the new CORESET may be indexed in a time-priority manner. In this case, the area in which the terminal monitors PDCCH candidates may be CCE12 to CCE23 (12 CCEs). Based on the CCE index, the terminal can recognize that the CCEs to be monitored for PDCCH candidates are the three CCEs in each of the four base CORESETs.

[0301] The CCEs of the base CORESETs that make up the new CORESET may be indexed independently. For example, if the number of CCEs constituting the first base CORESET among the base CORESETs that make up the new CORESET is N_CCE0, then each CCE constituting the first base CORESET may be indexed with one of the values ​​0, 1, ..., N_CCE0-1. Similarly, if the number of CCEs constituting the second base CORESET among the base CORESETs that make up the new CORESET is N_CCE0, then each CCE constituting the second base CORESET may be indexed with one of the values ​​0, 1, ..., N_CCE0-1. In this case, the terminal can determine which CCEs on the first base CORESET will receive the PDCCH. The terminal can receive the PDCCH at integration level L using L CCEs among the CCEs constituting the first base CORESET. The terminal can receive the PDCCH at integration level L using L CCEs among the CCEs constituting the second CORESET. In this case, the PDCCH received on the first CORESET and the PDCCH received on the second CORESET may contain the same DCI. That is, a terminal can repeatedly receive PDCCH on different underlying CORESETs that constitute a new CORESET. Here, L may be a power of 2. For example, L may have values ​​such as 1, 2, 4, 8, 16, 32, etc.

[0302] Figure 39 shows that PDCCH is repeatedly received on the basic control resource set according to one embodiment of the present invention.

[0303] Referring to Figure 39, the CCEs of the base CORESETs constituting a new CORESET may be indexed independently. A terminal can receive the first PDCCH at integration level 4 on the first base CORESET (base CORESET#0). In this case, the area monitored by the terminal to receive the PDCCH with integration level 4 may be CCE2, CCE3, CCE4, and CCE5 included in the first base CORESET (base CORESET#0). A terminal can receive the second PDCCH with integration level 4 on the second base CORESET (base CORESET#1). In this case, the area monitored by the terminal to receive the PDCCH with integration level 4 may be CCE2, CCE3, CCE4, and CCE5 included in the second base CORESET (base CORESET#1). Similarly, a 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. In this case, the DCIs included in the first, second, third, and fourth PDCCHs may be identical to each other. That is, a terminal can monitor and receive PDCCHs containing the same DCIs using 16 CCEs.

[0304] When REGs and REG bundles constitute a CCE, different interleaving may be applied to each underlying coreset. This is to distribute the CCEs contained within each underlying coreset across different frequency bands. This can facilitate multiplexing between any two underlying coresets that overlap.

[0305] The following explains how to apply interleaving to each base CORESET. First, if the index of the REG bundle that makes up the base CORESET is x, then the index of the interleaved REG bundle can be f(x). f(x) is as shown in the following number 7.

[0306]

number

[0307] With number 7, N REG CORESET is the number of REGs that make up the basic CORESET, and L may be the number of REGs that make up the REG bundle. Therefore, N REG CORESET / L may be the number of REG bundles in the basic CORESET. R may be one value among 2, 3, ~6. n shift is a shift value that may be applied when interleaving is performed on the index of the REG bundle that makes up each basic CORESET. n shift Based on this, the indexes of the REG bundles may be interleaved so as to be different. n shift may be a value set by the base station for the terminal, or may be the cell ID.

[0308] The base station can set different n shift values for each basic CORESET in order to interleave the indexes of different REG bundles of different basic CORESETs. The terminal can interleave the indexes of the REG bundles based on the n shift values set for each of the basic CORESETs.

[0309] The base station can set one value (n shift,0 ) for the terminal. At this time, the terminal can apply different n shift,0 values to each basic CORESET. For example, the terminal can determine a multiple of the n shift,0 value as the n shift value and interleave the indexes of the REG bundles. Also, the terminal can add a value based on the number of REG bundles to the n shift,0 value to determine the n shift value. For example, the n shift value is n shift,0 +N REG CORESETThe formula / L / N*n may be determined. In this case, N is the number of base CORESETs that make up a new CORESET, and n is the index of the base 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, one of the following operations—truncation, rounding up, or rounding down—is applied to the integer value n. shift,0 +N REG CORESET The value of / L / N*n can be determined. This is because the CCE index is evenly distributed by the number of REG bundles, which is n. shift This method sets the values ​​to be separated by only a certain amount.

[0310] Figure 40 shows an embodiment of the present invention in which a terminal applies interleaving to the basic control resource set to repeatedly receive PDCCH candidates.

[0311] Figure 40 shows an example of how to determine the index of the CCE constituting each base CORESET by using different interleaving for each base CORESET, when the CCEs of the base CORESETs constituting a new CORESET are indexed independently, as described above. Referring to Figure 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 the second base CORESET (base CORESET#1) has n shift n as a value shift,0 +N REG CORESET / L / N*1 is used, and the third base CORESET (base CORESET#2) has n shift n as a value shift,0 +N REG CORESET / L / N*2 is used, and the fourth base CORESET (base CORESET#3) has n shift n as a value shift,0 +N REG CORESET / L / N*3 may be used. In this case, L is 6, N is 4, N REG CORESET is 48, R is 2, n shift,0 n may be 0. shift Since the values ​​are applied, they may be interleaved differently in each base CORESET. In addition, the CCE0 of each base CORESET may be located in the lowest frequency range in the first base CORESET (base CORESET#0), in the frequency range corresponding to 1 / 4 of the total frequency band in the second base CORESET (base CORESET#1), in the frequency range corresponding to 2 / 4 of the total frequency band in the third base CORESET (base CORESET#2), and in the frequency range corresponding to 3 / 4 of the total frequency band in the fourth base CORESET. Thus, the CCE0 of each base CORESET can be distributed equally across the frequency band.

[0312] Referring to Figure 40, a terminal can receive a PDCCH at integrated level 4 on the first base CORESET (base CORESET#0). In this case, the area that the terminal monitors to receive a PDCCH with integrated level 4 may be CCE2, CCE3, CCE4, and CCE5 of the first base CORESET. Similarly, a terminal can receive a PDCCH at integrated level 4 by monitoring CCE2, CCE3, CCE4, and CCE5 in the second, third, and fourth base CORESETs, respectively. In this case, the PDCCH at integrated level 4 received on the first, second, third, and fourth base CORESETs, respectively, may contain the same DCI. By applying different interleavings to each base CORESET, CCE2, CCE3, CCE4, and CCE5 of each base CORESET can be distributed across the frequency domain. Therefore, this method is efficient in terms of frequency diversity.

[0313] The following describes how a terminal can receive PDCCH. In this case, PDCCH may be transmitted over a CORESET, which may be an existing CORESET or the new CORESET described above.

[0314] iii) Method C

[0315] The base station can transmit to the terminal information about one CORESET and information about multiple search spaces corresponding to one CORESET. Each of the multiple search spaces may have a period and an offset. In this case, the period and offset may be set on a slot basis. The information about the multiple search spaces may include information about the index of the start symbol that the terminal monitors in order to receive the PDCCH within the slot. The terminal can monitor and receive the PDCCH in a region determined based on the period and offset and the index of the start symbol of each of the multiple search spaces received from the base station. That is, the terminal can receive the PDCCH in each of the multiple search spaces corresponding to one CORESET. In this case, the DCIs contained in each PDCCH received in the multiple search spaces may be the same as those in the other. Therefore, the PDCCH may be transmitted repeatedly.

[0316] A base station can set an index in each of multiple search spaces in order to transmit a PDCCH containing the same DCI across multiple search spaces to a terminal. That is, the terminal can recognize that the indexed search spaces set by the base station transmit the same DCI to each other. For example, if the base station sets search space 1 and search space 2 to a terminal, the terminal can recognize that the DCIs contained in the PDCCH repeatedly transmitted in search space 1 and search space 2 are the same to each other. In this case, the periods of search space 1 and search space 2 may be the same to each other. That is, by setting the periods of multiple search spaces that transmit the same DCI to be the same, the terminal can determine the interval (resource area) in which the PDCCH is repeatedly transmitted. For example, if the periods of search space 1 and search space 2 are the same as P, the terminal can determine the slots with slot indices P*n, P*n+1, ..., P*n+P-1 as the interval in which the PDCCH is repeatedly transmitted, and the PDCCH containing the same DCI may be repeatedly transmitted in the multiple search spaces included in the determined interval. In this case, n may have values ​​of 0, 1, 2, ...

[0317] Figure 41 shows an example of the present invention in which PDCCH is repeatedly transmitted across multiple search spaces.

[0318] Referring to Figure 41, two search spaces may be set in one CORESET. Of the two search spaces, the first search space (search space#A) may have a period of 4 slots and an offset of 0 slots. Therefore, the terminal can monitor to receive PDCCH on the first search space (search space#A) in slots 0, 4, and 8. Of the two search spaces, the second search space (search space#B) may have a period of 4 slots and an offset of 1 slot. Therefore, the terminal can monitor to receive PDCCH on the second search space (search space#B) in slots 1, 5, and 9. If the terminal is configured to repeatedly receive PDCCH containing the same DCI on multiple search spaces, it can receive repeated PDCCH containing the same DCI on the search spaces of slots 0, 1, 2, and 3 based on a common period (the period of the first and second search spaces). Furthermore, the terminal can receive repeated PDCCHs that transmit the same DCI on the search space of slots 4, 5, 6, and 7 based on a common period.

[0319] On the other hand, the periods of the first search space and the second search space may be different. In this case, a resource area (interval) in which PDCCH is repeatedly transmitted needs to be defined. The interval in which PDCCH is repeatedly transmitted may be determined based on the least common multiple of the periods of the first search space and the second search space. The interval in which PDCCH is repeatedly transmitted may be determined based on the greatest common divisor of the periods of the first search space and the second search space. The interval in which PDCCH is repeatedly transmitted may be determined based on the relatively larger period of the periods of the first and second search spaces. The interval in which PDCCH is repeatedly transmitted may be determined based on the relatively smaller period of the periods of the first and second search spaces. The base station can separately transmit (set) the period of the interval in which PDCCH is repeatedly transmitted to the terminal.

[0320] The base station can transmit (set) multiple period and offset values ​​for a single search space to the terminal. The base station can also transmit (set) the index of the starting symbol for monitoring the terminal to receive PDCCHs across multiple slots. Based on the multiple period, offset value, and starting symbol index, the terminal can receive repeating PDCCHs containing the same DCI.

[0321] To transmit a PDCCH containing the same DCI in the search space, the base station can transmit (set) the period and offset value of a single search space to the terminal. The base station can also transmit (set) the index of the starting symbol that must be monitored to receive the PDCCH within a single slot to the terminal. In addition, the base station can specify the number of slots (K) for which the search spaces that the terminal repeatedly monitors are set. The number of slots (K) may be a natural number smaller than the period of the search space. Specifically, the search spaces that the terminal monitors to receive the PDCCH may be set by period. The search spaces may be set based on the index of the starting symbol within the slot specified by the base station. In other words, the search spaces may be set from the starting symbol indicated by the index. Furthermore, the base station can specify the number of slots (K) for which the search spaces that the terminal repeatedly monitors are set. For example, if the base station specifies a K value of 2, the search spaces may be set identically in slots n and n+1. In this case, the index of the symbol that starts the search space may be the same n as the slot index. Therefore, the search space in slot n and slot n+1 may be set starting from the symbol n of each slot.

[0322] Figure 42 shows that a PDCCH based on a search space and iteration setting is transmitted according to one embodiment of the present invention.

[0323] Referring to Figure 42, the period of the search space may be 4 slots and the offset may be 0 slots. Therefore, the search space may be set up with slots 0, 4, 8, ... In addition, the terminal may be instructed to set up 2 as the number of slots (K) for iteratively monitoring the search space. In this case, the search space for monitoring the iterative PDCCH that the terminal repeats may be set up in the slots immediately following the slots where the initial search space is set up (slots 0, 4, 8, ...) (slots 1, 5, 9, ...).

[0324] The base station can transmit (set) the period and offset value of a single search space to the terminal. The base station can also transmit (set) K indices of the starting symbols for PDCCH monitoring within a slot. Specifically, the terminal can perform monitoring based on the first index of the symbol in which monitoring for receiving PDCCH begins within slot n. For example, if the first index is 0, the search space is set from the first symbol in slot n, and the terminal can perform monitoring for PDCCH reception within the search space of slot n. The terminal can perform monitoring based on the second index of the symbol in slot n+1 where monitoring for receiving PDCCH begins. For example, if the second index is 2, the search space is set from the third symbol in slot n+1, and the terminal can perform monitoring for PDCCH reception within the search space of slot n+1.

[0325] Figure 43 shows an embodiment of the present invention in which PDCCH is transmitted with different starting symbol positions based on the search space and iteration settings.

[0326] Referring to Figure 43, the search space may be set with a period of 4 slots and an offset of 0 slots. Therefore, the search space may be set as 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 may start from symbol 0 in slot 0, slot 4, slot 8, ... and the iterative search space may start from symbol 7 in the next slot, slot 1, slot 5, slot 9, ...

[0327] A base station can configure multiple search spaces within a single CORESET slot. To do this, the base station can instruct the terminal on the starting symbol number (K) for each search space. For example, if the K value is 2, there may be two search spaces configured in slot n. Specifically, the first search space may begin to be configured from the first symbol of slot n, and the second search space may begin to be configured from the symbol immediately following the last symbol of the first search space.

[0328] A base station can configure multiple search spaces within a single CORESET slot. To do this, the base station can instruct the terminal of K indices for the starting symbols of the search spaces. For example, if the value of K is 2, the starting symbol indices specified 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 configured starting from the first symbol of slot n, and if the value of the second index is 2, the second search space may be configured starting from the third symbol of slot n.

[0329] In method C described above, since the region in which the PDCCH is transmitted is a single CORESET, the resources in the frequency domain are fixed to a portion of the bandwidth, and the number of symbols in the CORESET is also fixed. In this specification, a single CORESET can mean the same time-frequency domain resources set for each slot. Therefore, it is disadvantageous in terms of frequency diversity and has the problem that the number of symbols cannot be adjusted by the slot configuration. A method to solve these problems will be described below.

[0330] iv) Method D

[0331] A base station can configure multiple coresets on a single downlink BWP. The time-frequency domain resources of each of these multiple coresets may be configured independently. Additionally, one or more search spaces may be configured on each coreset. Specifically, each of the search spaces may be mapped to a coreset based on an indicator that identifies the coreset.

[0332] For example, each of the multiple CORESETs may have a different search space. The base station can send an indicator to the terminal that specifies a PDCCH to be repeatedly transmitted on multiple CORESETs. Specifically, the base station can send an indicator to the terminal that a PDCCH should be repeatedly transmitted on the first CORESET and the second CORESET. In this case, if the value of the indicator is 1, it indicates that the repeated PDCCH will be transmitted on the first search space corresponding to the first CORESET, and if the value of the indicator is 2, it indicates that the repeated PDCCH will be transmitted on the second search space corresponding to the second CORESET. In this case, the DCIs included in the PDCCH that are repeatedly transmitted on each of the multiple CORESETs may be the same.

[0333] For example, a base station can configure multiple coresets and one search space. Specifically, a terminal can receive an indicator from the base station indicating which of the multiple coresets a search space is mapped to. In addition, the terminal may receive (configure) the period, offset, and start symbol index of the search space from the base station. The search spaces determined based on the period, offset, and start symbol index may be sequentially mapped to multiple coresets. In this case, the DCI included in each PDCCH transmitted on multiple coresets may be the same. Since the DCI can be transmitted on multiple coresets, frequency diversity can be obtained.

[0334] Figure 44 shows that PDCCH is transmitted on a set of multiple control resources according to one embodiment of the present invention.

[0335] Referring to Figure 44, the period of the search space is 2 slots, and the offset may be 0 slots. Therefore, the search space may be set to slot 0, slot 2, slot 4, slot 6, slot 8, ... Each search space set to slot 0, slot 2, slot 4, slot 6, slot 8, ... may be mapped to one of two CORESETs (CORESET#A, CORESET#B). The odd-numbered search spaces (i.e., the search spaces set to slot 0, slot 4, and slot 8) may be mapped to CORESET#A, and the even-numbered search spaces (i.e., the search spaces set to slot 2 and slot 6) may be mapped to CORESET#B. In this case, the interval of the resource to which PDCCH is transmitted may be the same as the value obtained by multiplying the period of the search space by the number of CORESETs. That is, 4, which is obtained by multiplying the period of the search space (2) by the number of CORESETs (2), may be the interval of the resource to which PDCCH is transmitted, and the unit may be slots. The terminal can receive PDCCH signals in the interval between slots 0, 1, 2, and 3. Additionally, the terminal can receive PDCCH signals in the interval between slots 4, 5, 6, and 7.

[0336] The search space may be configured based on multiple periods, offsets, and start symbol indices set by the base station. Since multiple search spaces correspond to multiple CORESETs, the number of search spaces and the number of CORESETs may be the same. In other words, the number of sets of settings for each search space may be the same as the number of CORESETs. In this case, the sets may contain multiple periods, offsets, and start symbol indices. For example, a search space determined based on the first period, offset, and start symbol index may be mapped to the first CORESET, and a search space determined based on the second period, offset, and start symbol index may be mapped to the second CORESET.

[0337] Furthermore, the search space may be defined based on the number of slots (K) in which the search space is iterated. In this case, K may be the same as the number of CORESETs, and therefore K may be defined without any further signaling. For example, if K is 2, slot n is determined based on the period and offset, the search space determined in slot n based on the starting symbol index is mapped to the first CORESET, and the search space determined in slot n+1 based on the starting symbol index is mapped to the second CORESET.

[0338] Furthermore, the search space may be determined based on the number of indices in the starting symbol. In this case, the number of indices in the starting symbol and the number of CORESETs may be the same. For example, if there are two indices in the starting symbol, the search space determined in slot n based on the first starting symbol index may be mapped to the first CORESET, and the search space determined in slot n+1 based on the second starting symbol index may be mapped to the second CORESET.

[0339] v) Method E

[0340] This document describes how to receive DM-RS of repeating PDCCHs containing the same DCI transmitted from a base station to a terminal.

[0341] A wideband reference signal (RS) may be set. The terminal can determine whether the same precoder is assumed for each REG based on whether or not a wideband RS is set.

[0342] If broadband RS is not set, the terminal can assume that the REGs constituting the REG bundle have the same precoder applied. That is, the terminal can perform channel estimation using the DM-RS of the REGs included in the REG bundle. Based on the channel estimation result, the terminal can compensate for the phase of the signal received by the REs included in the REGs constituting the REG bundle.

[0343] When broadband RS is configured, a terminal can assume that the same precoder is applied to adjacent REGs in the time-frequency domain. A terminal can 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 each be regions where the same DCI is transmitted. Also, a terminal can 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, PDCCHs containing the same DCI may be transmitted in the search space. A terminal can assume that the same precoder is applied to adjacent REGs in the time-frequency domain among REGs included in a single CORESET. In other words, a terminal does not assume that REGs in different CORESETs have the same precoder applied even if they are adjacent to each other in the time-frequency domain. Different CORESETs may include CORESETs where the same DCI is repeatedly transmitted. On the other hand, CORESETs where the same DCI is repeatedly transmitted may be excluded from different CORESETs. A terminal can assume that the same precoder is applied to adjacent REGs in the time-frequency domain within a single search space. That is, even if adjacent REGs in the time-frequency domain are included in the same CORESET, the terminal does not assume that the same precoder is applied if they correspond to different search spaces. Different search spaces may include search spaces to which the same DCI is transmitted. On the other hand, different search spaces may exclude search spaces to which the same DCI is transmitted.

[0344] The terminal can assume that the same precoder is applied to the REGs in the region where PDCCH is repeatedly transmitted (multiple base CORESETs constituting one CORESET, or multiple search spaces corresponding to one CORESET, or multiple CORESETs). The regions where PDCCH is repeatedly transmitted do not necessarily have to be adjacent in the time-frequency domain. That is, the terminal can assume that the same precoder is applied to the REGs included in regions that are not adjacent in the time-frequency domain. As a result, the terminal can assume that the same precoder is applied to regions that are not adjacent in the time-frequency domain, and therefore, the channel estimation performance using DM-RS is improved.

[0345] For a base station to transmit a repeating PDCCH containing the same DCI to a terminal, the REs of some symbols in the resource area may not be used for DM-RS and may instead be used to transmit the DCI. For example, if a repeating PDCCH containing the same DCI is configured to be transmitted on adjacent symbols, the base station does not need to assign DM-RS to the REs of all symbols used to transmit each of the repeating PDCCHs. In this case, all or some of the symbols to which DM-RS is not assigned may be used to transmit the DCI. Each of the repeating PDCCHs may be adjacent PDCCHs in the resource area. The specific method for assigning DM-RS in this case is described below.

[0346] i) A base station does not have to include DM-RS in some or all of the REs corresponding to the symbols transmitted by the k-th PDCCH in a repeating PDCCH. For example, if k is 2, the base station does not have to assign DM-RS to some or all of the symbols transmitted by the PDCCH that are multiples of 2 (i.e., even-numbered) in a repeating PDCCH. ii) A base station does not have to assign DM-RS to some or all of the REs corresponding to each symbol that is a multiple of k in a repeating PDCCH where DM-RS is repeatedly transmitted to each symbol that is a multiple of k. For example, if k is 2, the base station does not have to assign DM-RS to some or all of the REs corresponding to each symbol that is a multiple of 2 (i.e., even-numbered) in a repeating PDCCH. iii) A base station does not have to assign DM-RS to the RE corresponding to each k-th symbol in a repeating PDCCH, but does not have to assign DM-RS to the REs corresponding to the remaining symbols excluding the k-th symbol. For example, if k is 1, a DM-RS is assigned to the RE corresponding to the first symbol of each iterative PDCCH, and DM-RS does not need to be mapped to the REs corresponding to the remaining symbols excluding the first symbol. iv) The base station assigns DM-RS to the REs corresponding to the first to kth symbols of each iterative PDCCH, and does not need to assign DM-RS to all or some of the REs corresponding to the remaining symbols excluding the first to kth symbols. For example, if k is 2, the base station assigns DM-RS to the REs corresponding to the first and second symbols of each iterative PDCCH, and does not need to assign DM-RS to all or some of the remaining REs excluding the REs corresponding to the first and second symbols. In iii) and iv) above, the value of k may be determined based on the number of symbols transmitted in the PDCCH. For example, k may be determined as ceil(PDCCH_length / 2), where PDCCH_length is the number of symbols transmitted in the PDCCH. That is, if the number of symbols transmitted in the PDCCH is 1 or 2, k is 1, and if the number of symbols is 3, k is 2. In this case, the k value may be a value set by the base station.

[0347] vi) Method F

[0348] The same sequence may be used for DM-RS assigned to repeating PDCCHs containing the same DCI. That is, a terminal can assume that the same sequence is used for DM-RS assigned to repeating PDCCHs and determine that the DCIs included in the repeating PDCCHs are identical. Furthermore, a terminal can perform phase compensation by using or comparing the DM-RS assigned to repeating PDCCHs. The DCIs included in repeating PDCCHs may be identical.

[0349] More specifically, slot n μ s,f The DM-RS sequence assigned to symbol l may be determined as shown in the following number 8.

[0350]

number

[0351] In equation 8, the initial value of the pseudo-random sequence c(i) may be calculated as shown in equation 9 below.

[0352]

number

[0353] In number 9, n μ s,f l is the index of the slot within the subframe, l is the index of the symbol within the slot, and N ID This value can be one of 0, 1, ..., 65535, or it can be the same value as the cell ID.

[0354] The following describes how to apply the same sequence to DM-RS assigned to repeating PDCCH.

[0355] i) The sequences used for DM-RS assigned to repeating PDCCHs may have the same initial value. The initial value can be determined using the index of the slot to which the first PDCCH is transmitted and its symbol index. The determined initial value may be used for each symbol in the slot to which the repeating PDCCH is transmitted. For example, the first PDCCH of the repeating PDCCH may be transmitted with symbols i and i+1 in slot n1, and the second PDCCH of the repeating PDCCH may be transmitted with symbols j and j+1 in slot n2. In this case, the initial value of the DM-RS sequence of the second PDCCH may be the same as the initial value of the DM-RS sequence of the first PDCCH. That is, the initial value of the sequence used for DM-RS assigned to the first symbol of the second PDCCH is c init (n1,i) and the initial value of the sequence used for DM-RS, which is assigned to the second symbol of the second PDCCH, is c init (n1, i+1) is acceptable. ii) When a repeating PDCCH is transmitted on a single slot, the index value I of the symbols in the resource area transmitting the repeating PDCCH may all be set to the same value. For example, if a repeating PDCCH is repeated four times on a single slot, specifically, the first repeating PDCCH may be transmitted on symbols 0-2, the second repeating PDCCH on symbols 3-5, the third repeating PDCCH on symbols 6-8, and the fourth repeating PDCCH on symbols 9-11. In this case, the index value l of the first symbol in the area transmitting each repeating PDCCH (i.e., symbols 0, 3, 6, 9) 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 yet another example, the index value of the symbol on which the first PDCCH of the repeating PDCCH is transmitted may be set to the value I. That is, the index value of the symbol on which the remaining PDCCHs of the repeating PDCCH are transmitted, excluding the first PDCCH, may be I. iii) When repeated PDCCHs are transmitted on different slots, the slot index value n in the initial DM-RS μ s,fAll of these values ​​may be the same. For example, n in the first slot where PDCCH is repeatedly transmitted. μ s,f It can be set to 0, and the n of the second slot μ s,f It may be set to 1. As another example, n μ s,f n may be the index of the slot to which the first PDCCH of the iterative PDCCH is sent. That is, n of the remaining PDCCHs excluding the first PDCCH. μ s,f This may be the same as the index of the slot to which the first PDCCH is transmitted.

[0356] iv)n μ s,f This can be applied identically to N slots. For example, n μ s,f is, c init (floor(n μ s,f / N)*N,l) may be determined. floor(x) is a function that returns the largest integer less than or equal to x. N may be a value set by the base station. N may be a value determined based on the number of slots to which the repeating PDCCH is transmitted. N may be the same as the number of slots to which the repeating PDCCH is transmitted. v)n μ s,f This can be used identically in N slots, with a specific slot as the reference (for example, slot n0). For example, n μ s,f is, c init (floor((n μ s,f -n0) / N)*N,l) may be determined. N may be a value set by the base station. N may be a value determined based on the number of slots to which the repeating PDCCH is transmitted. N may be the same as the number of slots to which the repeating PDCCH is transmitted. n0 may be the index of the slot to which the first PDCCH of the repeating PDCCH is transmitted. n0 may be set by the base station.

[0357] The CCEs corresponding to the PDCCH candidates in the first search space of the first CORSET and the PDCCH candidates in the second search space of the second CORSET, which transmit repeating PDCCHs containing the same DCI, may be determined based on a hash function. The number of blind decodings required to monitor repeating PDCCH candidates and receive the repeating PDCCH in the first search space may differ from the number of blind decodings required to monitor repeating PDCCHs and receive the repeating PDCCH in the second search space. That is, the maximum number of blind decodings and the number of non-overlapping CCEs may differ for each slot (or for a particular time interval). Therefore, a terminal may be able to receive repeating PDCCHs in the first search space (i.e., satisfying the conditions for the maximum number of blind decodings and the number of non-overlapping CCEs), but not in the second search space. Consequently, it is difficult to extend coverage by repeatedly receiving repeating PDCCHs. The following describes how to apply hash functions to extend coverage.

[0358] vii) Method G

[0359] The same hash function may be applied to regions where iterative PDCCH containing the same DCI is repeatedly transmitted (multiple base CORESETs constituting one CORESET, multiple search spaces corresponding to one CORESET, or multiple CORESETs).

[0360]

number

[0361]

number

[0362]

number

[0363]

number

[0364] N CCE,p M may be the number of CCEs that make up the CORESET. (L) s,max n may be the number of repeating PDCCH candidates whose aggregation level monitored by the terminal is L. cI This may be the value indicated by the carrier indicator field.

[0365]

number

[0366] The following describes how to determine the specific number. If the number of CCEs constituting multiple CORESETs differs from one another, the specific number may be determined based on the CORESET with the fewest CCEs. Alternatively, the specific number may be determined based on the CORESET with the most CCEs. Alternatively, the specific number may be determined based on the CORESET to which the first PDCCH of an iterative PDCCH is sent. Alternatively, the specific number may be determined based on the CORESET with the lowest index among multiple CORESETs. Alternatively, the specific number may be determined based on the CORESET with the highest index among multiple CORESETs.

[0367]

number

[0368] Figure 45 is a flowchart showing that a repeating PDCCH is transmitted according to an embodiment of the present invention.

[0369] Referring to Figure 45, the method by which repeated PDCCHs containing the same DCI are transmitted, as described above in Figures 1 to 44, will be explained.

[0370] The terminal can receive configuration information regarding the first CORESET and configuration information regarding the second CORESET from the base station (S4510, S4520).

[0371] The terminal can receive the first PDCCH transmitted on the first CORESET from the base station and the second PDCCH transmitted on the second CORESET (S4530, S4540).

[0372] At this time, the first PDCCH and the second PDCCH may be transmitted repeatedly from the base station, respectively.

[0373] The first DCI included in the first PDCCH and the second DCI included in the second PDCCH may be identical to each other.

[0374] The first PDCCH and the second PDCCH may be set to the same aggregation level (AL).

[0375] The first CORESET and the second CORESET may be resources in different time-frequency domains, or they may be resources in the same time-frequency domain.

[0376] The first PDCCH and the second PDCCH may be transmitted repeatedly within the same slot, or they may be transmitted repeatedly on different slots.

[0377] The first DCI and the second DCI may be decoded independently, or they may be decoded together. In this case, if the terminal is unable to decode the first DCI and the second DCI independently, the terminal can decode them together.

[0378] The terminal can receive configuration information regarding the first search space and configuration information regarding the 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. Furthermore, the first PDCCH may be received in the first search space, and the second PDCCH may be received in the second search space.

[0379] The configuration information relating to the first search space may include information relating to the period of the first search space, and the configuration information relating to the second search space may include information relating to the period of the second search space. In this case, the periods of the first search space and the second search space may be the same.

[0380] The terminal can transmit HARQ-ACK information to the base station for either the first PDCCH or the second PDCCH. In this case, the HARQ-ACK information may be HARQ-ACK information for a PDCCH transmitted in the search space of the lower index among the index of the first search space and the index of the second search space.

[0381] The terminal can receive a third PDCCH from the base station in the third search space. The terminal can transmit HARQ-ACK information to the base station for any one of the first PDCCH, the second PDCCH, and the third PDCCH. In this case, the third PDCCH may include a third DCI that is 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, the HARQ-ACK information may be HARQ-ACK information for a PDCCH transmitted in the search space with the lowest index among the overlapping search spaces.

[0382] 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.

[0383] The terminal performing the method described in Figure 45 may be the terminal described in Figure 11. Specifically, the terminal may include a communication module for transmitting and receiving wireless signals and a processor for controlling the communication module. In this case, the terminal's processor can perform the method for receiving repeating PDCCHs as described herein.

[0384] Furthermore, the base station that transmits the repeating PDCCH described herein may include a communication module for transmitting and receiving radio signals, and a processor for controlling the communication module. In this case, the base station may be the base station described in Figure 11. In this case, the processor of the base station can perform the method for transmitting the repeating PDCCH described herein.

[0385] Although the methods and systems of the present invention have been described in relation to specific embodiments, some or all of their components or operations can be implemented using a computer system having a general-purpose hardware architecture.

[0386] The above description of the present invention is illustrative, and a person with ordinary skill in the art to which the present invention pertains will understand that it can be easily modified into other specific forms without altering the technical idea or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative and not limiting in any respect. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

[0387] The scope of the present invention is expressed more by the claims described below than by the above detailed description, and all modifications or altered forms derived from the meaning and scope of the claims and the concept of equivalents should be interpreted as being included within the scope of the present invention.

Claims

1. A terminal configured to operate in a wireless communication system, Transmitter and receiver Includes a processor that controls the aforementioned transceiver, The aforementioned processor, A step of receiving first configuration information relating to a set of multiple control resources (CORESET), wherein the set of multiple CORESETs includes a first CORESET and a second CORESET, and the first CORESET and the second CORESET are located on different resources; A step in which each receives second configuration information relating to a plurality of search spaces associated with each of the plurality of CORESETs, wherein the second configuration information includes link information indicating that a first search space and a second search space are linked among the plurality of search spaces; The step of receiving first downlink control information (DCI) included in the first physical downlink control channel (PDCCH) in the first search space; A step of receiving a second DCI included in the second PDCCH in the second search space, wherein the first DCI and the second DCI are identical to each other; and A terminal configured to perform the steps of transmitting a physical uplink control channel (PUCCH) carrying a hybrid automatic retransmission request (HARQ)-acknowledgment (ACK) on a resource, wherein the resource is determined based on the PDCCH of the first PDCCH and the second PDCCH on a search space having a lower search space index than the first search space and the second search space.

2. The terminal according to claim 1, wherein the first PDCCH and the second PDCCH have the same aggregation level (AL).

3. The terminal according to claim 1, wherein the first search space and the second search space are configured in the same slot.

4. The terminal according to claim 1, wherein the first DCI and the second DCI are each decoded independently.

5. The terminal according to claim 1, wherein the period of the first search space and the period of the second search space are the same as each other.

6. The type of the first search space and the type of the second search space are identical to each other. The terminal according to claim 1, wherein 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.

7. A method performed by a terminal configured to operate in a wireless communication system, A step of receiving first configuration information relating to a set of multiple control resources (CORESET), wherein the set of multiple CORESETs includes a first CORESET and a second CORESET, and the first CORESET and the second CORESET are located on different resources; A step in which each receives second configuration information relating to a plurality of search spaces associated with each of the plurality of CORESETs, wherein the second configuration information includes link information indicating that a first search space and a second search space are linked among the plurality of search spaces; The step of receiving first downlink control information (DCI) included in the first physical downlink control channel (PDCCH) in the first search space; A step of receiving a second DCI included in the second PDCCH in the second search space, wherein the first DCI and the second DCI are identical to each other; and A method comprising the step of transmitting a physical uplink control channel (PUCCH) on a resource that carries a hybrid automatic retransmission request (HARQ)-acknowledgment (ACK), wherein the resource is determined based on a PDCCH of the first PDCCH and the second PDCCH on a search space having a lower search space index than the first PDCCH and the second PDCCH.

8. The method according to claim 7, wherein the first PDCCH and the second PDCCH have the same aggregation level (AL).

9. The method according to claim 7, wherein the first search space and the second search space are configured in the same slot.

10. The method according to claim 7, wherein the first DCI and the second DCI are each decoded independently.

11. The method according to claim 7, wherein the period of the first search space and the period of the second search space are the same as each other.

12. The type of the first search space and the type of the second search space are identical to each other. The method according to claim 7, wherein 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.

13. A base station configured to operate in a wireless communication system, Transmitter and receiver Includes a processor that controls the aforementioned transceiver, The aforementioned processor, A step of transmitting first configuration information relating to a set of multiple control resources (CORESET), wherein the set of multiple CORESETs includes a first CORESET and a second CORESET, and the first CORESET and the second CORESET are located on different resources; A step in which each transmits second configuration information relating to a plurality of search spaces associated with each of the plurality of CORESETs, wherein the second configuration information includes link information indicating that a first search space and a second search space are linked among the plurality of search spaces; A step of transmitting the first downlink control information (DCI) included in the first physical downlink control channel (PDCCH) on the first search space; A step of transmitting a second DCI included in a second PDCCH on the second search space, wherein the first DCI and the second DCI are identical to each other; and A base station configured to perform the step of receiving a physical uplink control channel (PUCCH) carrying a hybrid automatic retransmission request (HARQ)-acknowledgment (ACK) on a resource, wherein the resource is determined based on the PDCCH of the first PDCCH and the second PDCCH on a search space having a lower search space index than the first search space and the second search space.

14. The base station according to claim 13, wherein the first PDCCH and the second PDCCH have the same aggregation level (AL).

15. A method performed by a base station configured to operate in a wireless communication system, A step of transmitting configuration information relating to a set of multiple control resources (CORESET), wherein the set of multiple CORESETs includes a first CORESET and a second CORESET, and the first CORESET and the second CORESET are located on different resources; A step in which each transmits second configuration information relating to a plurality of search spaces associated with each of the plurality of CORESETs, wherein the second configuration information includes link information indicating that a first search space and a second search space are linked among the plurality of search spaces; A step of transmitting the first downlink control information (DCI) included in the first physical downlink control channel (PDCCH) on the first search space; A step of transmitting a second DCI included in a second PDCCH on the second search space, wherein the first DCI and the second DCI are identical to each other; and A method comprising the step of receiving a physical uplink control channel (PUCCH) on a resource that carries a hybrid automatic retransmission request (HARQ)-acknowledgment (ACK), wherein the resource is determined based on a PDCCH of the first PDCCH and the second PDCCH on a search space having a lower search space index than the first PDCCH and the second PDCCH.

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