Method and apparatus for transmitting and receiving a signal in a wireless communication system

Abstract

The disclosure relates to a method and apparatus for transmitting and receiving a signal in a wireless communication system, and an operation method of a user equipment (UE) in a wireless communication system can include receiving, from a base station, configuration information related to carrier aggregation (CA), wherein the configuration information related to CA includes information related to cross-carrier scheduling between a primary cell (PCell) and a secondary cell (SCell), performing a configuration related to CA based on the configuration information related to CA, monitoring a common search space (CSS) of the PCell on the PCell and a UE-specific search space (USS) of the SCell on the SCell based on the performed configuration related to CA, and receiving a physical downlink control channel (PDCCH) based on the monitoring.

Description

TECHNICAL FIELD

[0001] The disclosure relates to a method and apparatus for transmitting and receiving a signal in a wireless communication system. BACKGROUND

[0002] To meet increasing demand for wireless data traffic since commercialization of a fourth generation (4G) communication system, efforts have been made to develop an improved fifth generation (5G) or pre-5G communication system. For this reason, the 5G or pre-5G communication system is also called a beyond 4G network communication system or a post long term evolution (LTE) system. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To mitigate a propagation loss of radio waves and increase a transmission distance, beamforming, massive multiple-input multiple-output (massive MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beamforming, large scale antennas techniques are discussed for use in the 5G communication system. In addition, to improve network systems for the 5G communication system, various technologies for improving spectral efficiency have been developed, including evolved small cells, advanced small cells, cloud radio access networks (Cloud-RAN), ultra-dense networks, a device-to-device (D2D) communication, wireless backhaul, moving networks, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation.

[0003] In addition, the Internet has evolved from a human-centered connection network, where humans create and consume information, to an Internet of things (IoT), where distributed components such as objects exchange information with each other to process the information. Internet of everything (IoE) technologies have emerged through the convergence of the IoT technology with, e.g., technology for processing big data through connection with a cloud server. To implement the IoT, technologies such as a sensing technology, a wired / wireless communication and network infrastructure, a service interface technology, and a security technology are required, and thus recent studies have been conducted in, e.g., a sensor network, machine to machine (M2M) communication, and machine-type communication (MTC) as technologies for interconnecting objects. In the IoT environment, intelligent Internet technology services can be provided to collect and analyze data obtained from objects connected with each other to create a new value in a human life. The IoT can be applied to a variety of fields such as smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. outside of the existing IT field.

[0004] Therefore, various attempts are being made to apply the 5G communication system to the IoT network. For example, the 5G communication techniques such as beamforming, MIMO, array antennas, etc. are applied to the technical fields of sensor networks, M2M communication, MTC, etc. The application of the cloud RAN as the above-described big data processing technique can also be an example of convergence between the 5G technology and the IoT technology.

[0005] As various services can be provided by utilizing the progress in the wireless communication system as described above, a method for seamlessly providing the services is required. SUMMARY

[0006] Based on the above discussion, the disclosure provides an apparatus and method for efficiently providing services in a mobile communication system. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 A basic structure of a time-frequency resource domain for a fifth generation (5G) system is shown.

[0008] Figure 2 An example of a frame structure of a 5G system is shown.

[0009] Figure 3 Another example of a frame structure for a 5G system is shown.

[0010] Figure 4 Another example of a frame structure for a 5G system is shown.

[0011] Figure 5 A time-domain mapping structure for a synchronization signal and a beam sweeping operation are shown.

[0012] Figure 6 A random access procedure is shown.

[0013] Figure 7 A procedure in which a user equipment (UE) reports UE capability information to a base station is shown.

[0014] Figure 8 is a diagram showing a carrier aggregation (CA) concept.

[0015] Figure 9 is a diagram showing a self-carrier scheduling method in CA.

[0016] Figure 10 is a diagram showing a cross-carrier scheduling method in CA.

[0017] FIG. 11A shows an example in which a long term evolution (LTE) and a 5G system overlap in the same frequency band.

[0018] FIG. 11B shows an example in which an LTE and a 5G system partially overlap in a frequency domain.

[0019] Figure 12 A basic structure of a time-frequency resource domain of an LTE system is shown.

[0020] Figure 13 FIG. is a diagram illustrating a method of avoiding collision between LTE and 5G signals in a dynamic spectrum sharing (DSS) system.

[0021] Figure 14 FIG. is a diagram illustrating a search space after initial access by a user equipment (UE) in a wireless communication system according to an embodiment of the disclosure.

[0022] Figure 15 FIG. is a diagram illustrating a method of configuring a new radio (NR) physical downlink control channel (PDCCH) search space in a wireless communication system according to an embodiment of the disclosure.

[0023] Figure 16 FIG. is a flowchart of a method of monitoring a NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure.

[0024] Figure 17 FIG. is a diagram illustrating another method of configuring a NR PDCCH search space in a wireless communication system according to an embodiment of the disclosure.

[0025] Figure 18 FIG. is a flowchart of another method of monitoring a NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure.

[0026] Figure 19 FIG. is a diagram illustrating another method of configuring a NR PDCCH search space in a wireless communication system according to an embodiment of the disclosure.

[0027] Figure 20 FIG. is a flowchart of another method of monitoring a NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure.

[0028] Figure 21 FIG. is a diagram illustrating a procedure for configuring CA in a wireless communication system according to an embodiment of the disclosure.

[0029] Figure 22 FIG. is a diagram illustrating a transmitter and a receiver of a UE in a wireless communication system according to an embodiment of the disclosure.

[0030] Figure 23 FIG. is a block diagram of a configuration of a UE according to an embodiment of the disclosure.

[0031] Figure 24 FIG. is a block diagram of a configuration of a base station according to an embodiment of the disclosure.

[0032] Figure 25 FIG. 1 is a diagram illustrating a UE performing an NR PDCCH monitoring operation according to a SCell activation command in a wireless communication system according to an embodiment of the disclosure.

[0033] Figure 26 FIG. 2 is a diagram illustrating a UE performing an NR PDCCH monitoring operation according to a SCell deactivation command in a wireless communication system according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0034] According to an embodiment of the disclosure, an operation method of a user equipment (UE) in a wireless communication system can include receiving, from a base station, configuration information related to carrier aggregation (CA), wherein the configuration information related to CA includes information related to cross-carrier scheduling between a primary cell (PCell) and a secondary cell (SCell), performing a configuration related to CA based on the configuration information related to CA, monitoring a common search space (CSS) of the PCell on the PCell and a UE-specific search space (USS) of the SCell on the SCell based on the performed configuration related to CA, and receiving a physical downlink control channel (PDCCH) based on the monitoring.

[0035] According to an embodiment of the disclosure, a UE in a wireless communication system can include a transceiver, and at least one processor configured to: receive, from a base station via the transceiver, configuration information related to CA, wherein the configuration information related to CA includes information related to cross-carrier scheduling between a PCell and a SCell, perform a configuration related to CA based on the configuration information related to CA, monitor a CSS of the PCell on the PCell and a USS of the SCell on the SCell based on the performed configuration related to CA, and receive, via the transceiver, a PDCCH based on the monitoring.

[0036] [Embodiments of the disclosure]

[0037] Hereinafter, the operation principle of the disclosure will be described in detail with reference to the accompanying drawings. Also, in the following description of the disclosure, when it is considered that well-known functions or configurations related to the disclosure will unnecessarily confuse the essence of the disclosure, these functions or configurations are not described in detail. Also, the terms to be described later are defined by considering the functions described in the disclosure, and can be changed according to the intention or habit of a user or an operator. Therefore, the terms should be defined based on the overall description in the specification.

[0038] The present disclosure and the method of implementing the same can be understood by referring to the following description and the accompanying drawings in conjunction with the described embodiments. The present disclosure can be implemented in numerous ways, including but not limited to a method, a system, a device, a process, or a computer readable medium having computer readable instructions. However, the present disclosure should not be construed as being limited to the embodiments set forth in this section by reference to the drawings.

[0039] It should be understood that each block of the flowchart of the figures, and combinations of blocks in the flowchart, can be implemented by computer program instructions. These computer program instructions can be loaded onto a general purpose computer, a special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions can also be stored in a computer- executable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer- executable or computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which operate on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowchart block or blocks.

[0040] In addition, each block can represent a module, segment, or portion of code, which includes one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the flowcharts. For example, two blocks shown in succession can in fact be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved.

[0041] As used herein, the term "unit" indicates a software element or a hardware element, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), and performs some functions. However, the term "unit" is not limited to software or hardware. The "unit" can be configured as in an addressable storage medium, or can be configured to operate one or more processors. Therefore, the term "unit" may, for example, include elements such as software elements, object-oriented software elements, class elements, and task elements, processes, functions, attributes, procedures, sub-routines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, or variables. The functions provided by elements and "units" can be combined into a smaller number of elements and "units", or can be divided into additional elements and "units". In addition, elements and "units" can be implemented to reproduce one or more central processing units (CPUs) in an apparatus or a secure multimedia card. In addition, in an embodiment, a "unit" can include one or more processors.

[0042] In the following description of the disclosure, when it is considered that the well-known functions or configurations related to the essence of the disclosure will unnecessarily confuse the disclosure, the related well-known functions or configurations are not described in detail. Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

[0043] As used in the following description, in order to facilitate description, terms indicating an access node, terms indicating a network entity, terms indicating a message, terms indicating an interface between network entities, terms indicating various types of identification information, and the like are exemplified. Therefore, the disclosure is not limited to the terms to be described later, and other terms representing objects having equivalent technical meanings can also be used.

[0044] In the following description, a physical channel and a signal can be used interchangeably with data or a control signal. For example, a physical downlink shared channel (PDSCH) is a term referring to a physical channel on which data is transmitted, but the PDSCH can also be used to refer to data. That is, in the disclosure, the expression "transmitting a physical channel" can be interpreted to have the same meaning as the expression "transmitting data or a signal through a physical channel".

[0045] Hereinafter, in the disclosure, high layer signaling refers to a signal transmission method in which a signal is transmitted from a base station (BS) to a terminal using a physical layer downlink data channel, or a signal is transmitted from a terminal to a BS via a physical layer uplink data channel. The high layer signaling can be understood as radio resource control (RRC) signaling or medium access control (MAC) control element (CE).

[0046] Hereinafter, the disclosure uses terms and names defined in the 3rd Generation Partnership Project New Radio (3GPP NR) standard for convenience of description. However, the disclosure is not limited to the terms and names, and can be equally applied to systems conforming to other standards. In the disclosure, a next-generation Node B (gNB) can be used interchangeably with an evolved Node B (eNB) for convenience of description. In other words, a BS described as an eNB can represent a gNB. In addition, the term "terminal" can refer to a mobile phone, a machine type communication (MTC) device, a narrow-band Internet of Things (NB-IoT) device, a sensor, and other wireless communication devices.

[0047] Hereinafter, a BS is an entity that allocates resources to a terminal, and can be at least one of a gNB, an eNB, a Node B, a BS, a wireless access unit, a BS controller, or a network node. A terminal can include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. However, the terminal is not limited to the above-described examples.

[0048] Recently, in order to handle explosively increasing mobile data traffic, an initial standard of a 5th generation (5G) system or a new radio (NR) access technology, which is a next-generation communication system after long term evolution (LTE) or evolved universal terrestrial radio access (E-UTRA) and LTE-Advanced (LTE-A) or E-UTRA evolution, has been determined. While the existing mobile communication system focuses on general voice / data communication, the 5G system aims to meet various services and requirements, such as an enhanced mobile broadband (eMBB) service for improving the existing voice / data communication, an ultra-reliable low-latency communication (URLLC) service, a massive MTC (mMTC) service for supporting intercommunication between a large number of devices, etc.

[0049] Compared to a conventional LTE and LTE-A system in which a maximum system transmission bandwidth per carrier is limited to 20 megahertz (MHz), the 5G system mainly aims to provide a data service at an ultra-high speed of several gigabits per second (Gbps) by using a super wide bandwidth much wider than the conventional LTE and LTE-A system. Accordingly, for the 5G system, a super-high frequency band from several gigahertz (GHz) to 100 GHz is considered as a candidate frequency, in which a frequency having a super wide bandwidth is easily available. In addition, by reallocating or configuring frequencies in a frequency band included in a range of several hundred megahertz (MHz) to several GHz used in the existing mobile communication system, a wideband frequency for the 5G system can be obtained.

[0050] Radio waves in an ultra-high frequency band have a wavelength of several millimeters (mm) and are also referred to as millimeter waves (mmWave). However, in the ultra-high frequency band, the path loss of radio waves increases as the frequency increases, and thus, the coverage of a mobile communication system can decrease.

[0051] To overcome the problem of the decrease in coverage in the ultra-high frequency band, a beamforming technique is applied to increase a radio wave reachable distance by focusing radiated energy of radio waves to a certain target point using a plurality of antennas. In other words, a signal to which the beamforming technique is applied has a relatively narrow beam width, and the radiated energy is concentrated within the narrow beam width, thereby increasing the radio wave reachable distance. The beamforming technique can be applied at both a transmitter and a receiver. In addition to increasing the coverage, the beamforming technique also achieves an effect of reducing interference in an area other than a beamforming direction. To properly implement the beamforming technique, an accurate transmission / reception beam measurement and feedback method are required. The beamforming technique can be applied to a control channel or a data channel having a one-to-one correspondence between a specific UE and a BS. In addition, to increase the coverage, the beamforming technique can be applied to a control channel and a data channel through which a BS transmits a common signal, such as a synchronization signal, a physical broadcast channel (PBCH), and system information, to a plurality of UEs in a system. When the beamforming technique is applied to the common signal, a beam sweeping technique of transmitting a signal by changing a beam direction is also applied to allow the common signal to reach a UE located at any position within a cell.

[0052] As another requirement for a 5G system, a super low latency service requiring a transmission delay of about 1 ms between a transmitter and a receiver is required. As one method for reducing the transmission delay, a frame structure based on a shorter transmission time interval (TTI) than LTE and LTE-A is required to be designed. The TTI is a basic time unit for performing scheduling, and the TTI in the legacy LTE and LTE-A system corresponds to one subframe having a length of 1 ms. For example, as a short TTI for satisfying the super low latency service requirement in the 5G system, a TTI of 0.5 ms, 0.25 ms, 0.125 ms, etc. shorter than the TTI in the legacy LTE and LTE-A system can be supported.

[0053] The disclosure relates to a method and apparatus for a UE to transmit and receive a signal in a wireless communication system to which carrier aggregation (CA) is applied.

[0054] The disclosure relates to a cellular wireless communication system, and a method of transmitting and receiving a control channel and a data channel by a UE performing a CA operation.

[0055] The disclosure can provide a method for removing scheduling constraints due to a shortage of radio resources in a mobile communication system.

[0056] The disclosure can define a method of scheduling a UE in a mobile communication system supporting CA, thereby solving a problem of a shortage of cell capacity that can occur in a given cell.

[0057] Figure 1 A basic structure of a time-frequency resource domain for a 5G system is shown. In other words, Figure 1 is a diagram showing a basic structure of a time-frequency resource domain as a radio resource area for transmitting a data or control channel in a 5G system.

[0058] Referring to Figure 1 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. In the 5G system, the minimum transmission unit in the time domain is an orthogonal frequency division multiplexing (OFDM) symbol, One OFDM symbol 102 can be combined to form one slot 106, and Ten slots can be combined to form one subframe 105. The length of the subframe can be 1.0 ms, and ten subframes can be combined into a frame 114 of 10 ms. The minimum transmission unit in the frequency domain is a subcarrier, and the entire system transmission bandwidth can consist of a total of N BW subcarriers 104.

[0059] The basic resource unit in the time-frequency domain is a resource element (RE) 112 that can be represented by an OFDM symbol index and a subcarrier index. A resource block (RB) can be defined as contiguous subcarriers 110 in the frequency domain. In the 5G system, And the data rate can be increased in proportion to the number of RBs scheduled to the UE.

[0060] In the 5G system, the BS can map data in units of RBs, and scheduling to a specific UE is usually performed in units of RBs constituting one slot. In other words, in the 5G system, the basic time unit for scheduling can be a slot, and the basic frequency unit for scheduling can be an RB.

[0061] The number of OFDM symbols is determined based on the length of a cyclic prefix (CP) added to each symbol to prevent inter-symbol interference, and for example, when a normal type CP is applied, And when an extended type CP is applied, An extended CP can be applied to a system having a relatively longer radio wave transmission distance than a normal CP, thereby maintaining orthogonality between symbols. For a normal CP, a ratio of a CP length to a symbol length can be maintained at a constant value to maintain a constant overhead caused by the CP regardless of a subcarrier spacing. In other words, as the subcarrier spacing becomes narrower, the symbol length increases, and thus, the CP length also increases. On the other hand, as the subcarrier spacing becomes wider, the symbol length decreases, and thus, the CP length also decreases. The symbol length and the CP length can be inversely proportional to the subcarrier spacing.

[0062] In the 5G system, in order to meet various services and requirements, various frame structures can be supported by adjusting a subcarrier spacing. For example,

[0063] - In terms of the operating band, a wider subcarrier spacing is more advantageous for recovery from phase noise of a high frequency band.

[0064] - In terms of transmission time, when the subcarrier spacing becomes wider, the symbol length in the time domain is shortened, which results in a shorter slot, and thus, a wider subcarrier spacing is more advantageous for supporting an ultra-low latency service such as URLLC.

[0065] - In terms of cell size, as the CP length becomes longer, a larger cell can be supported, and thus, as the subcarrier becomes narrower, a relatively larger cell can be supported. The cell is a concept indicating an area covered by one BS in mobile communication.

[0066] The subcarrier spacing, the CP length, and the like are basic information for OFDM transmission and reception, and the BS and the UE need to identify the information as a common value to achieve seamless transmission and reception. Table 1 shows a relationship between a subcarrier spacing configuration μ, a subcarrier spacing Δf, and a CP length supported by the 5G system.

[0067] [Table 1]

[0068]

[0069] Table 2 shows the number of symbols per slot , the number of slots per frame , and the number of slots per subframe for each subcarrier spacing configuration μ in the case of a normal CP.[Table 2]

[0070]

[0071] Table 3 shows the number of symbols per slot , the number of slots per frame , and the number of slots per subframe .

[0072] [Table 3]

[0073]

[0074] Figure 2 、 Figure 3 and Figure 4 respectively show examples of frame structures when subcarrier spacing configuration μ is 0, 1, and 2 and a normal type CP is used. In the examples of Figure 2 、 Figure 3 and Figure 4 , subcarrier spacing, CP length, slot length, etc. are included as basic numerologies defining frame structures.

[0075] In an early stage of introduction of a 5G system, it is desirable to coexist or operate in dual mode with at least a legacy LTE / LTE-A system. Accordingly, the legacy LTE / LTE-A system can provide stable system operation to a UE, and the 5G system can provide enhanced services to the UE. Accordingly, the frame structure of the 5G system needs to include at least the frame structure or basic numerology (subcarrier spacing = 15 kHz) of the legacy LTE / LTE-A system.

[0076] Figure 2 shows an example of a frame structure of a 5G system. In other words, Figure 2 shows a 5G frame structure or basic numerology that is substantially the same as that of LTE / LTE-A.

[0077] Referring to Figure 2 , Figure 2 is an example of a frame structure with subcarrier spacing configuration μ = 0, in which the subcarrier spacing is 15 kHz, 14 symbols constitute one slot of 1 ms, and 12 subcarriers (= 180 kHz = ) constitute one RB. In this case, 1 slot can constitute one subframe, and 10 subframes can constitute one frame.

[0078] Figure 3 shows another example of a frame structure for a 5G system.

[0079] Referring to Figure 3 , Figure 3 is an example of a frame structure with subcarrier spacing configuration μ = 1, in which the subcarrier spacing is 30 kHz, 14 symbols constitute one slot of 0.5 ms, and 12 subcarriers (= 360 kHz = 12 x 30 kHz) constitute one RB. In other words, Figure 3 the subcarrier spacing and RB size in the frame structure of Figure 2 are twice as large as those in the frame structure of Figure 3 the slot length and symbol length in the frame structure ofFigure 2 The time slot length and symbol length in the frame structure are less than half. In this case, two time slots can form a subframe, and 20 subframes can form a frame.

[0080] Figure 4 Another example of a frame structure for a 5G system is shown.

[0081] refer to Figure 4 , Figure 4 An example is a frame structure with a subcarrier spacing configuration of μ=2, where the subcarrier spacing is 60kHz, 14 symbols constitute a 0.25ms subframe, and 12 subcarriers (=720kHz=12×60kHz) constitute a RB. In other words, Figure 4 The ratio of subcarrier spacing to RB size in the frame structure Figure 2 The subcarrier spacing and RB size in the frame structure are 4 times larger, while Figure 4 The ratio of slot length to symbol length in the frame structure Figure 2 The time slot length and symbol length in the frame structure are four times smaller. In this case, four time slots can form a subframe, and 40 subframes can form a frame.

[0082] In other words, when referring to Figure 2 to Figure 4 When the frame structure is generalized, high scalability can be provided by increasing or decreasing the subcarrier spacing, CP length, time slot length, etc. (which are a basic set of parameters) of each frame structure by integer factors compared to another frame structure. Additionally, a fixed-length 1ms subframe can be defined as an indicator reference time unit, regardless of the frame structure type.

[0083] Figure 2 to Figure 4 The frame structure described can be applied to / correspond to various scenarios. Regarding cell size, since larger cells can be supported as the CP length increases, it is compatible with... Figure 3 and Figure 4 Compared to the frame structure, Figure 2 The frame structure can support relatively large cells. In terms of operating frequency band, a wider subcarrier spacing is more conducive to recovery from phase noise in higher frequency bands, therefore... Figure 2 and Figure 3 Compared to the frame structure, Figure 4 The frame structure can support relatively high operating frequencies. From a service perspective, the smaller time slot length, as the basic scheduling unit, is more advantageous for supporting ultra-low latency services such as URLLC. Figure 2 and Figure 3 Compared to the frame structure, Figure 4 The frame structure is more suitable for URLLC services.

[0084] In the following description of the disclosure, uplink (UL) refers to a radio link through which a UE transmits data or a control signal to a BS, and downlink (DL) refers to a radio link through which a BS transmits data or a control signal to a UE.

[0085] During an initial access procedure in which a UE first accesses a system, the UE can perform a cell search to obtain DL time and frequency synchronization and obtain a cell identity (ID) from a synchronization signal transmitted by a BS. Then, the UE can receive a PBCH using the obtained cell ID, and obtain a master information block (MIB) as basic system information from the PBCH. In addition, the UE can receive system information (e.g., system information blocks (SIBs)) transmitted by the BS to obtain control information related to cell-common transmission / reception. The control information related to cell-common transmission / reception can include control information related to random access, control information related to paging, common control information about various physical channels, etc.

[0086] A synchronization signal is used as a reference for cell search, and a subcarrier spacing can be applied to the synchronization signal of each frequency band and is to be adapted to a channel environment (e.g., phase noise). For a data channel or a control channel, different subcarrier spacings can be applied according to a service type in order to support various services as described above.

[0087] Figure 5 A time domain mapping structure and a beam sweeping operation for a synchronization signal are shown.

[0088] For description, the following components can be defined.

[0089] - Primary synchronization signal (PSS): It is a signal used as a reference for DL time / frequency synchronization.

[0090] - Secondary synchronization signal (SSS): It is used as a reference for DL time / frequency synchronization and provides cell ID information. The SSS can also be used as a reference signal for PBCH demodulation.

[0091] Physical broadcast channel (PBCH): The PBCH can provide a master information block, which is basic system information required for a UE to transmit and receive a data channel and a control channel. The basic system information can include search space-related control information indicating radio resource mapping information of a control channel, scheduling control information for a separate data channel for transmitting system information, information such as a system frame number (SFN), which is a frame-level index that becomes a timing reference.

[0092] SS / PBCH block (or SSB): An SS / PBCH block consists of N OFDM symbols and is a combination of PSS, SSS, and PBCH. For a system using a beam sweeping technique, an SS / PBCH block is the smallest unit to which beam sweeping is applied. In the 5G system, N = 4. A BS can transmit up to L SS / PBCH blocks, and the L SS / PBCH blocks are mapped within a half frame (0.5 ms). In addition, the L SS / PBCH blocks are periodically repeated with a period P. The BS can inform a UE of the period P via signaling. If there is no independent signaling for the period P, the UE applies a predetermined default value.

[0093] Figure 5 It is shown that beam sweeping is applied in units of SS / PBCH blocks over time. In the example of FIG. 5, a first UE (UE1) 505 can receive an SS / PBCH block via a beam radiating in direction #d0 503 due to beamforming applied to SS / PBCH block #0 at time point t1501. In addition, a second UE (UE2) 506 can receive an SS / PBCH block via a beam radiating in direction #d4504 due to beamforming applied to SS / PBCH block #4 at time point t2502. A UE can obtain the best synchronization signal via a beam radiating from the BS toward the UE location direction. For example, UE1 505 can have difficulty obtaining time / frequency synchronization signals and basic system information from an SS / PBCH block via a beam radiating in direction #d4504 away from UE1 505. Figure 5

[0094] In addition to receiving an initial access procedure, a UE can receive an SS / PBCH block to determine whether radio link quality of a current cell is maintained above a certain threshold level. In addition, in performing a procedure for a UE to handover from a current cell to a neighboring cell, the UE can receive an SS / PBCH block from the neighboring cell in order to determine radio link quality of the neighboring cell and obtain time / frequency synchronization of the neighboring cell.

[0095] After a UE obtains an MIB and system information from a BS through an initial access procedure, the UE can perform a random access procedure to switch a link with the BS to a connected state (or RRC_CONNECTED state). After the random access procedure is completed, the UE transitions to the connected state, and one-to-one communication is enabled between the BS and the UE. Hereinafter, the random access procedure will be described in detail with reference to FIG. 6. Figure 6 The random access procedure is shown in FIG. 6.

[0096] Figure 6 The random access procedure is shown in FIG. 6.

[0097] Reference is made to FIG. 6. Figure 6 ​In the first step 610 of the random access procedure, the UE transmits a random access preamble to the BS. In the random access procedure, the random access preamble transmitted as the first message by the UE can be referred to as message 1. The BS can measure a propagation delay value between the UE and the BS from the random access preamble and implement UL synchronization. In this case, the UE can randomly select a random access preamble to be used from a set of random access preambles given in advance by system information. In addition, the initial transmission power of the random access preamble can be determined according to the path loss between the BS and the UE measured by the UE. In addition, the UE can transmit the random access preamble by determining a transmission beam direction for the random access preamble and based on a synchronization signal received from the BS.

[0098] In step 2 620, the BS transmits an UL transmission timing control command to the UE based on the propagation delay value measured from the random access preamble received in step 1 610. The BS can also transmit to the UE an UL resource to be used by the UE and a power control command as scheduling information. Control information about the UL transmission beam of the UE can be included in the scheduling information.

[0099] If the UE does not successfully receive a random access response (RAR) (or message 2) as message 3 from the BS within a certain period of time in the second step 620, the UE can perform the first step 610 again. If the UE performs the first step 610 again, the UE can transmit the random access preamble with transmission power increased by a certain step (power ramping step), thereby increasing the probability of receiving the random access preamble at the BS.

[0100] In the third step 630, the UE transmits UL data (message 3) including its UE ID to the BS through an UL data channel (e.g., a physical UL shared channel (PUSCH)) by using the UL resource allocated in the second step 620. The transmission timing of the UL data channel for transmitting message 3 can be controlled according to the timing control command received from the BS in the second step 620. In addition, the transmission power of the UL data channel for transmitting message 3 can be determined by considering the power control command received from the BS in the second step 620 and the power ramping value applied to the random access preamble. The UL data channel for transmitting message 3 can refer to the first UL data signal transmitted by the UE to the BS after the UE transmits the random access preamble.

[0101] In the fourth step 640, when the BS determines that the UE has performed the random access procedure without collision with another UE, the BS can transmit data including a UE ID to the corresponding UE which has transmitted UL data in the third step 630 (message 4). Upon receiving the signal transmitted by the BS in the fourth step 640, the UE can determine that the random access procedure is successful. In addition, the UE can transmit hybrid automatic repeat request acknowledgement (HARQ-ACK) information to the BS, which indicates whether the message 4 has been successfully received through the UL control channel (e.g., physical UL control channel (PUCCH)).

[0102] If the data transmitted by the UE in the third step 630 collides with data transmitted by another UE, and thus the BS cannot receive the data signal from the UE, the BS can no longer transmit data to the UE. Accordingly, if the UE fails to receive the data transmitted by the BS in the fourth step 640 within a certain period of time, the UE can determine that the random access procedure has failed, and restart the random access procedure from the first step 610.

[0103] Upon successful completion of the random access procedure, the UE can transition to a connected state, and one-to-one communication between the BS and the UE is enabled. The BS can receive UE capability information from the UE in the connected state, and adjust scheduling based on the UE capability information of the corresponding UE. The UE can inform the BS of whether the UE itself supports a specific function, a maximum allowable value of a function supported by the UE, etc., via the UE capability information. Accordingly, the UE capability information reported to the BS by each UE can have different values for each UE.

[0104] As an example, the UE can report the UE capability information including at least some of the following control information to the BS as the UE capability information.

[0105] - Control information related to a frequency band supported by the UE

[0106] - Control information related to a channel bandwidth supported by the UE

[0107] - Control information related to a highest modulation scheme supported by the UE

[0108] - Control information related to a maximum number of beams supported by the UE

[0109] - Control information related to a maximum number of layers supported by the UE

[0110] - Control information related to channel state information (CSI) reporting supported by the UE

[0111] - Control information on whether the UE supports frequency hopping

[0112] - Control information related to bandwidth when CA is supported

[0113] - Control information on whether cross-carrier scheduling is supported when CA is supported

[0114] Figure 7 A procedure in which a UE reports UE capability information to a BS is shown.

[0115] Reference Figure 7 In operation 710, the BS 702 can transmit a UE capability information request message to the UE 701. In operation 720, in response to the request for UE capability information from the BS, the UE transmits UE capability information to the BS.

[0116] Hereinafter, a scheduling method is proposed in which a BS transmits DL data or indicates UL data transmission performed by a UE to the UE.

[0117] Downlink control information (DCI) is control information transmitted by a BS to a UE via a DL link, and can include DL data scheduling information or UL data scheduling information for a specific UE. In general, the BS can independently channel-encode DCI for each UE and then transmit it to the corresponding UE through a physical downlink control channel (PDCCH), which is a physical control channel for DL.

[0118] The BS can apply and operate a DCI format predefined for a UE to be scheduled according to the following purposes, such as whether the DCI carries scheduling information for DL data (DL assignment), whether the DCI carries scheduling information for UL data (UL grant), whether spatial multiplexing using multiple antennas is applied, whether the DCI is DCI for power control, etc.

[0119] The BS can transmit DL data to the UE through a PDSCH, which is a physical channel for DL data transmission. The BS can inform the UE of scheduling information via DCI related to DL data scheduling information in DCI transmitted on the PDCCH, such as a specific mapping location of the PDSCH in a time-frequency domain, a modulation scheme, HARQ-related control information, power control information, etc.

[0120] The UE can transmit UL data to the BS through a PUSCH, which is a physical channel for UL data transmission. The BS can inform the UE of scheduling information via DCI related to UL data scheduling information in DCI transmitted through the PDCCH, such as a specific mapping location of the PUSCH in a time-frequency domain, a modulation scheme, HARQ-related control information, power control information, etc.

[0121] As described above, in order to implement an ultra-high speed data service of several Gbps in the 5G system, signal transmission and reception over an ultra-wide bandwidth of several tens to several hundreds of MHz or several GHz can be supported. The signal transmission and reception over the ultra-wide bandwidth can be supported by a single component carrier (CC) or a CA technology of combining multiple CCs. In the case where a mobile operator fails to obtain a sufficiently high bandwidth frequency to provide an ultra-high speed data service by a single CC, the CA technology can combine single component carriers having a relatively small bandwidth to increase the total frequency bandwidth, thereby implementing an ultra-high speed data service.

[0122] Figure 8 is a diagram illustrating a CA concept.

[0123] Figure 8 An example of configuring a 5G system by combining three CCs for each of UL and DL is illustrated. In the CA system, each CC can be classified as a primary cell (PCell) or a secondary cell (SCell) for operation. The PCell (or first cell) can be a cell that provides a basic radio resource to a UE and is used by the UE as a reference cell to perform operations such as initial access and handover operations. The PCell can consist of a DL primary frequency (or primary component carrier; PCC) and a UL primary frequency. The UE can transmit UL control information (UCI) including feedback information HARQ ACK / NACK indicating whether data received from the BS is erroneous, CSI indicating a channel state between the BS and the UE, etc. through a PUCCH which is a UL control channel, and the PUCCH can be transmitted on the PCell. Also, the SCell (or second cell) is a cell that provides an additional radio resource to the UE together with the PCell, and can include a DL secondary frequency (or secondary component carrier (SCC)) and a UL secondary frequency, or only a DL secondary frequency. The CCs can be configured independently of each other, and DL CA and UL CA can be independently applied. For example, CA of combining one 100 MHz bandwidth CC and two 50 MHz bandwidth CCs can be applied for DL, whereas only one 100 MHz bandwidth component carrier can be used in UL (i.e., CA can not be applied to UL). In the present disclosure, unless otherwise specified, the terms "cell" and "CC" can be used interchangeably without considering the difference thereof. The BS can notify the UE of configurations related to CA, such as which CC to combine, how many CCs to combine, or control information related to each CC bandwidth, via signaling.

[0124] In the CA system, control information and data can be independently generated and transmitted for each CC. In detail, a method of scheduling a UE in the CA system can be divided into two types: a self-carrier scheduling method and a cross-carrier scheduling method.

[0125] Figure 9is a diagram illustrating a self-carrier scheduling method in CA.

[0126] Referring to Figure 9 , it is assumed that two DL CCs (CC#0 901 and CC#1 902) are combined in a 5G system. In Figure 9 an example, a BS can transmit DL data channels (e.g., PDSCHs 905 and 907) to any UE through CC#0 901 and CC#1 902. In this case, a PDCCH 904 for scheduling the PDSCH 905 on CC#0 901 can be transmitted to the UE through CC#0 901, and a PDCCH 906 for scheduling the PDSCH 907 on CC#1 902 can be transmitted to the UE through CC#1 902. As described above, a scheduling method in which a data channel and a control channel for scheduling the data channel are transmitted on the same carrier or the same cell can be referred to as self-carrier scheduling.

[0127] Figure 10 is a diagram illustrating a cross-carrier scheduling method when CA is applied.

[0128] Figure 10 An example of a system in which CA is applied to two DL CCs (CC#0 1001 and CC#1 1002) is illustrated. Referring to Figure 10 , a BS can transmit DL data channels (e.g., PDSCHs 1005 and 1007) to any UE through CC#0 1001 and CC#1 1002. In this case, a PDCCH 1004 for scheduling the PDSCH 1005 on CC#0 1001 and a PDCCH 1006 for scheduling the PDSCH 1007 on CC#1 1002 can both be transmitted to the UE on CC#0 1001. In other words, in the case of CC#1 1001, a data channel and a control channel for scheduling the data channel can be transmitted on different carriers or different cells. Such a scheduling method can be referred to as cross-carrier scheduling.

[0129] Although the DL CA technology has been described with reference to Figure 9 and Figure 10 , examples of Figure 9 and Figure 10 can also be equally applied to the UL CA technology.

[0130] Compared to self-carrier scheduling, cross-carrier scheduling can achieve the following effects.

[0131] 1) Control channel offloading: When radio resources for transmitting a control channel on a certain carrier are not sufficient, the control channel can be transmitted on a separate carrier in which radio resources are relatively sufficient. For example, in Figure 10In this case, assuming that CC#1 has a bandwidth of 20 MHz and CC#0 has a bandwidth of 100 MHz, radio resources for transmitting a control channel on CC#0 can be sufficient.

[0132] 2) Control channel interference management: Relatively strong interference can occur in a specific carrier due to factors from the surrounding environment, frequency characteristics, etc. Due to the interference, performance of control channel transmission and reception can be deteriorated, and such performance deterioration of the control channel transmission and reception can be avoided by transmitting the control channel on a carrier in which the interference is relatively slight. On the other hand, even if an error occurs in transmission and reception of a data channel, the data channel can be recovered through HARQ operation, and thus the data channel suffers less performance deterioration due to interference than the control channel.

[0133] Dynamic spectrum sharing (DSS) is now described. The following scenario can be referred to as DSS or LTE-NR coexistence: LTE and 5G systems are deployed and operated in the same frequency band or are deployed and operated in a frequency band in which LTE and 5G systems overlap in the frequency domain. In a system operating DSS, whether to schedule LTE or 5G to a UE can be adjusted according to changes in LTE traffic and 5G traffic. In the early stage of installation of a 5G system in which LTE traffic gradually decreases and 5G traffic gradually increases, DSS can maximize the use of existing frequencies to facilitate the expansion of 5G without additional frequency allocation. From the perspective of a telecommunications service provider, DSS operation allows efficient use of already used frequencies without wasting them.

[0134] FIGS. 11A and 11B are diagrams illustrating a DSS concept.

[0135] FIG. 11A illustrates an example in which LTE and 5G systems overlap in the same frequency band.

[0136] Referring to FIG. 11A, according to the distribution of LTE traffic and 5G traffic, a BS can determine when to schedule LTE and when to schedule 5G. FIG. 11A illustrates an example in which LTE is scheduled during a time period T1 and 5G is scheduled during a time period T2.

[0137] FIG. 11B illustrates an example in which LTE and 5G systems partially overlap in the frequency domain.

[0138] Referring to FIG. 11B, FIG. 11B illustrates an example in which LTE is scheduled in a frequency region F1 during a time period T1 and 5G is scheduled in a frequency region F2 during the time period T1. Also, in the example of FIG. 11B, 5G is scheduled in a frequency region F3 (= F1 + F2) during a time period T2. Although both FIG. 11A and FIG. 11B illustrate that LTE and 5G share time / frequency resources, it is possible to minimize deterioration of transmission and reception performance by preventing LTE and 5G from colliding with each other in the time / frequency resources at any moment.

[0139] Before describing collision avoidance between LTE and 5G in a DSS system, refer to Figure 12 A DL radio resource structure of an LTE system is described.

[0140] Figure 12 A basic structure of a time-frequency resource domain of an LTE system is illustrated. That is, Figure 12 A basic structure of a time-frequency domain as a radio resource region in which data or control channels are transmitted on a DL of an LTE system is illustrated, and a mapping relationship of DL physical channels and signals.

[0141] The basic structure is basically similar to the basic structure of a 5G system described with reference to Figure 1 , but in LTE, unlike the 5G system, a subcarrier spacing is generally fixed to 15 kHz regardless of a frequency band, and there are control channels and signals that fixedly occupy time-frequency resources.

[0142] Referring to Figure 12 , a horizontal axis represents a time domain, and a vertical axis represents a frequency domain. A minimum transmission unit in the time domain is an OFDM symbol 1201, two OFDM symbols (typically ) can be combined to form one slot, and two slots can be combined to form one subframe of 1 ms in length, and 10 subframes are combined to form a radio frame of 10 ms in length. A minimum transmission unit in the frequency domain is a subcarrier 1202, and the entire system bandwidth 1203 can be composed of a total of N BW subcarriers. The value of N BW may be proportional to the entire system bandwidth. A basic resource unit in the time-frequency domain is an RE 1204 that can be represented by an OFDM symbol index and a subcarrier index. Each of an RB 2305 and an RB 1206 (or a physical RB (PRB)) can be defined as contiguous OFDM symbols in the time domain and contiguous subcarriers (typically ) in the frequency domain. Accordingly, one RB can be composed of REs.

[0143] The LTE DL control channel 1210 can be mapped into the first N OFDM symbols in the time domain and onto the entire system bandwidth in the frequency domain in a subframe for transmission to the UE. The time-frequency region to which the LTE DL control channel is mapped can be referred to as a "control region." The BS can change the value of N for each subframe according to the amount of control information to be transmitted in the current subframe. Generally, the value of N = {1, 2, 3}. The PHICH can be mapped onto the OFDM symbols according to an independent configuration indicated by the BS within the N OFDM symbols. As the control channel, there can be a physical control format indicator channel (PCFICH) including an indicator indicating the value of N, a PDCCH including UL or DL scheduling information, and a physical HARQ indicator channel (PHICH) including a HARQ ACK / NACK signal indicating whether UL data has been successfully received. The PCFICH can be mapped to the first symbol in the first N OFDM symbols in a subframe, and the PDCCH can be mapped onto the N OFDM symbols. The PHICH can be mapped onto the OFDM symbols according to an independent configuration indicated by the BS within the N OFDM symbols.

[0144] The PDSCH 1211, which is an LTE DL physical data channel, can be mapped into the remaining portion of a subframe in which the DL control channel is not transmitted in the time domain and onto the frequency region indicated by the LTE PDCCH in the frequency domain for transmission to the UE.

[0145] The BS can transmit a reference signal (hereinafter, referred to as RS) to be used by the UE to measure a DL channel state or demodulate a PDSCH. The RS is also referred to as a pilot signal. The RSs can be classified into a cell-specific reference signal (CRS) 1212 that can be commonly received by UEs in a cell, a CSI-RS that supports multiple antennas but uses fewer resources per antenna port than the CRS, and a demodulation reference signal (DMRS) used by the UE to demodulate a PDSCH scheduled to the UE. For convenience, the CRS is shown in Figure 12 .

[0146] The DMRS for the PDSCH can be mapped to a predetermined location in the time-frequency domain for the PDSCH scheduled by the BS. In the case of the CSI-RS, the BS can control and operate a transmission period and its mapping location in the time-frequency domain. On the other hand, the CRS is repeatedly mapped to Figure 12 the REs shown in FIG. 11 and is transmitted in every subframe over the entire system bandwidth.

[0147] An antenna port is a logical concept, and an RS is defined for each antenna port, and the RS is used to measure a channel state corresponding to each antenna port. If the same RS is transmitted from multiple physical antennas, the UE cannot distinguish each physical antenna as a single antenna port.

[0148] The CRS is a cell common signal, and the UE can measure the CRS to perform the following operations.

[0149] 1) The UE determines a DL channel state from the CRS, and then reports the DL channel state to the BS to support BS scheduling.

[0150] 2) The UE demodulates a PDSCH received from the BS using the CRS as a reference signal.

[0151] 3) The UE determines whether a radio link between the BS and the UE is maintained above a certain threshold level.

[0152] 4) The UE supports a handover decision of the BS by measuring the CRS from a neighboring cell and reporting it to the BS.

[0153] Therefore, the BS can transmit the CRS at a fixed location for each subframe regardless of whether a PDSCH is transmitted to the UE within the subframe.

[0154] As described above, since the LTE "control region" and the LTE CRS often occupy a time-frequency domain in the LTE system, a method for avoiding a conflict between the LTE and the 5G is needed when transmitting the 5G signal using the DSS. Hereinafter, referring to Figure 13 A method for avoiding a conflict between the LTE and the 5G signal in a DSS system is described.

[0155] Figure 13 is a diagram illustrating a method for avoiding a conflict between the LTE and the 5G signal in a DSS system.

[0156] Referring to Figure 13 , the horizontal axis represents a time domain, and the vertical axis represents a frequency domain. In the example of Figure 13 , it is assumed that the LTE and the 5G system use the same frequency band, and thus overlap each other in the frequency domain. It is also assumed that the LTE and the 5G system both use the same subcarrier spacing of 15 kHz. For ease of description, the channels / signals in the LTE system can be distinguished from the channels / signals in the 5G system by adding the word "LTE" to the channels / signals in the LTE system and adding "NR" to the channels / signals in the 5G system. For example, a PDCCH for the LTE can be referred to as an LTE PDCCH, and a PDCCH for the 5G can be referred to as an NR PDCCH. As referring to Figure 12As described, reference numeral 1320 denotes the basic time-frequency domain structure of an LTE system for DL ​​(Deep Streaming), and indicates that the BS transmits LTE DL signals during time period 1301 (a subframe in LTE). The LTE DL signals may include LTE CRS 1304, LTE PDCCH 1305, and LTE PDSCH 1306. LTE PDCCH 1305 may include scheduling information for LTE PDSCH 1306. In structure 1320, an LTE "control area" occupying the first two symbols of the subframe is illustrated.

[0157] For reference Figure 1 As described, reference numeral 1350 denotes the basic time-frequency domain structure for a 5G system, in which NR PDCCH 1308, NR PDSCH 1309, and NR DMRS 1307 are mapped for NR PDSCH. In structure 1350, NRPDCCH 1308 can be mapped to the first two symbols in a time slot, and NR PDSCH 1309, scheduled by NR PDCCH 1308, can be mapped to the remainder of the time slot. Additionally, NR DMRS 1307 for NR PDSCH 1309 can be mapped to the third and tenth symbols within the time slot.

[0158] exist Figure 13 In the example, the BS can schedule the LTE PDSCH and send it to the LTE UE during time period 1301 according to structure 1320. (See reference...) Figure 13 During time period 1301, there may be no signal transmitted from the BS to the 5G UE. During time periods 1302 and 1303, NR PDSCH 1309 may be scheduled and transmitted to the 5G UE according to structures 1360 and 1370, respectively. Additionally, during time periods 1302 and 1303, the BS may transmit LTE CRS and LTE PDCCH according to structures 1330 and 1340, respectively. In this case, there may be no LTE PDSCH transmission. Reference numeral 1340 denotes an LTE Multimedia Broadcast Multicast Service (MBMS) Single Frequency Network (MBSFN) subframe, and compared to the general subframes in structures 1320 and 1330, the LTE MBSFN subframe 1340 has less overhead due to LTE CRS.

[0159] 1) Method 1 for avoiding conflicts between LTE and 5G signals: LTE CRS rate matching

[0160] In the DSS system, when a 5G DL signal is transmitted to a 5G UE, the BS maps and transmits the 5G DL signal by avoiding the location of the LTE CRS (LTE CRS rate matching). In addition, the BS informs the 5G UE of LTE CRS configuration information so that the 5G UE can receive the 5G DL signal at an accurate location. The LTE CRS configuration information can include the following information. The UE can learn the mapping location of the LTE CRS from the LTE CRS configuration information.

[0161] -v-Shift (0, 1, 2, 3, 4, 5): mapping offset of the LTE CRS from the RB boundary in the frequency domain, expressed in units of RB

[0162] -nrofCRS-Ports (1, 2, 4): number of LTE CRS antenna ports

[0163] -carrierFreqDL (0... 16383): center frequency of the LTE carrier

[0164] -carrierBandwidthDL (6, 15, 25, 75, 100): LTE carrier bandwidth expressed in units of RB

[0165] -mbsfn-SubframeConfigList (period, offset): LTE MBSFN subframe configuration information including the configuration period and timing offset of the LTE MBSFN subframe

[0166] In the example of FIG. 13, Figure 13 In the example of FIG. 13,

[0167] 2) Conflict avoidance method 2 for LTE and 5G signals: NR PDCCH mapping adjustment

[0168] An NR PDCCH to which a DL control channel for a 5G system is mapped can be referred to as a control resource set (CORESET). In the frequency domain, a CORESET can be configured in all or some of the frequency resources within a bandwidth supported by a UE. A CORESET can be configured in one or more OFDM symbols, which can be defined as a CORESET duration 404. A BS can configure one or more CORESETs to a UE via higher layer signaling (e.g., system information (SI), MIB, or RRC signaling). Configuring a CORESET to a UE refers to providing information such as a CORESET ID, a frequency location of the CORESET, a symbol length of the CORESET, etc. to the UE. The information provided by the BS to the UE to configure the CORESET can include at least some of the following information included in Table 4.

[0169] [Table 4]

[0170]

[0171] A CORESET can consist of RBs in the frequency domain and symbols in the time domain. An NR PDCCH can consist of one or more control channel elements (CCEs). A CCE can consist of 6 resource elements (REGs), and a REG can be defined as 1 RB in one OFDM symbol. In a CORESET, REGs can be indexed in a time-first manner, starting from REG index 0 of the first OFDM symbol and the lowest-numbered RB in the CORESET. 5G supports an interleaved method and a non-interleaved method as NR PDCCH transmission methods. A BS can configure a UE via higher layer signaling for each CORESET whether the transmission type is interleaved or non-interleaved. Interleaving can be performed in units of REG bundles. A REG bundle can be defined as a set of one or more REGs. Based on whether the transmission type is interleaved or non-interleaved configured by the BS, a UE can determine a CCE-to-REG mapping type for a corresponding CORESET in the manner shown in Table 5 below.

[0172] [Table 5]

[0173]

[0174]

[0175] In the 5G system, the BS can inform the UE of configuration information, such as the symbols to which the NR PDCCH is mapped in a slot, the transmission period, etc., through signaling.

[0176] In Figure 13 In the structure 1350, the NR PDCCH 1308 can be mapped to the first two symbols in a slot and transmitted. During the time period 1302 in which LTE and 5G coexist, according to the structure 1360, the NR PDCCH can be mapped to the third symbol in the slot (1310) by avoiding the time-frequency resources occupied by the LTE PDCCH and the LTE CRS, thereby avoiding the conflict between LTE and 5G.

[0177] 3) Conflict avoidance method 3 for LTE and 5G signals: adjusting the position of the DMRS for the NR PDSCH

[0178] In the 5G system, the BS configures the mapping position of the DMRS for the NR PDSCH and informs the UE of the mapping position through signaling. For example, in the structure 1350, Figure 13 the DMRS for the NR PDSCH can be mapped to the third and tenth symbols in a slot. During the time period 1302 in which LTE and 5G coexist, according to the structure 1360, the DMRS for the NR PDSCH can be mapped to the fourth and tenth symbols in the slot (1313) by avoiding the time-frequency resources occupied by the LTE PDCCH and the LTE CRS, thereby avoiding the conflict between LTE and 5G.

[0179] 4) Conflict avoidance method 4 for LTE and 5G signals: NR PDSCH mapping adjustment

[0180] In the 5G system, the BS informs the UE of the time-frequency resource information of the NR PDSCH via the NR PDCCH that schedules the NR PDSCH.

[0181] For example, in the case of the structure 1350, Figure 13 the NR PDSCH can be mapped to the third to fourteenth symbols in a slot. During the time period 1302 in which LTE and 5G coexist, according to the structure 1360, the NR PDSCH can be mapped to the fourth to fourteenth symbols in the slot (1311) by avoiding the time-frequency resources occupied by the LTE PDCCH, thereby avoiding the conflict between LTE and 5G. Using the conflict avoidance method 1 for LTE and 5G signals, the conflict between the NR PDSCH and the LTE CRS can be avoided.

[0182] 5) Conflict avoidance method 5 for LTE 5G signals: LTE MBSFN subframe adjustment

[0183] By configuring MBSFN in certain subframes (LTE MBSFN subframes) in the LTE system, LTE CRS mapping frequency within the LTE MBSFN subframes can be reduced, and the time domain size of the LTE "control region" can be limited. For example, the LTE CRS mapping symbols in the LTE MBSFN subframes can be limited to the first one or two symbols in the subframe, and the time domain size of the LTE "control region" in the LTE MBSFN subframes can be limited to the maximum of the first two symbols in the subframe. Reference numeral 1340 shows a structure in which the time period 1303 is configured as an LTE MBSFN subframe of the LTE system. Therefore, for the case of LTE and 5G coexistence in the time period 1303, the 5G signal only needs to be mapped in this way to avoid the LTE CRS and the LTE "control region" being mapped onto the first two symbols in the LTE MBSFN subframe. That is, by avoiding the NRPDCCH mapping to the third symbol in the slot by avoiding the time-frequency resources occupied by the LTE PDCCH, mapping the DMRS of the NR PDSCH to the fourth and tenth symbols in the slot, and mapping the NR PDSCH according to the structure 1370 to the fourth to fourteenth symbols in the slot, the conflict between the LTE and 5G signals can be avoided.

[0184] 6) Conflict avoidance method 6 for LTE and 5G signals: 5G UL transmission frequency shift

[0185] Unless there is a separate configuration, the frequency domain mapping of the 5G UL signal is offset by half a subcarrier spacing based on a subcarrier spacing of 15 kHz from the frequency domain mapping of the LTE UL signal. Therefore, for the case of LTE and 5G signal coexistence in the UL during the time periods 1302 and 1303, the frequency domain mapping of the 5G UL signal can be mapped by shifting up to half a subcarrier spacing (= 7.5 kHz). The BS signals the UE via signaling that the mapping of the UL signal is shifted by 7.5 kHz in the frequency domain. Figure 13

[0186] Since the DSS system is a mechanism that allows LTE and 5G to share time-frequency resources, if the 5G traffic is too large, scheduling constraints can occur due to a shortage of radio resources for scheduling LTE UEs. On the other hand, when the LTE traffic is too large, scheduling constraints can occur due to a shortage of radio resources for scheduling 5G UEs. In particular, due to the limitations of NR PDCCH resource mapping, the radio resources of the NR PDCCH can be relatively insufficient compared to the NR PDSCH.

[0187] ​Hereinafter, in order to overcome the scheduling constraint of the 5G UE, a method of performing cross-carrier scheduling by a 5G cell on a cell implementing DSS (for convenience of description, hereinafter referred to as a DSS cell) after applying 5G CA (Carrier Aggregation) to the 5G cell and the DSS cell is described through specific embodiments of the present disclosure.

[0188] <First Embodiment>

[0189] The first embodiment describes a method of configuring a search space for an NR PDCCH when CA is used to aggregate a DSS cell and a 5G cell and the 5G cell performs cross-carrier scheduling on the DSS cell.

[0190] First, a search space for an NR PDCCH is described as follows. Depending on an aggregation level (AL), the number of CCEs required to transmit an NR PDCCH can be 1, 2, 4, 8, or 16, and different numbers of CCEs can be used to implement link adaptation of a DL control channel. For example, when AL=L, one DL control channel can be transmitted using L CCEs. Since a UE does not know information about a DL control channel, the UE can perform blind decoding to detect a signal, and a search space representing a set of CCEs can be defined for blind decoding. The search space is a set of candidate DL control channels, each consisting of a CCE, intended for the UE to attempt decoding at a given AL, and since there are various ALs corresponding to sets of 1, 2, 4, 8, and 16 CCEs, respectively, the UE can have multiple search spaces. A search space set can be defined as a set of search spaces at all configured ALs.

[0191] The search space can be divided into a common search space (CSS) and a UE-specific search space (USS). A specific group of UEs or all UEs can monitor the CSS for an NR PDCCH in order to receive cell-common control information, such as a dynamically scheduled (SIB) system information or a paging message. For example, a UE can receive scheduling allocation information for an NR PDSCH for receiving system information by monitoring the CSS for an NR PDCCH. For the CSS, since a specific group of UEs or all UEs need to receive an NR PDCCH, the CSS can be defined as a predetermined set of CCEs. A UE can receive scheduling allocation information for a UE-specific NR PDSCH or an NR PUSCH by monitoring the USS for an NR PDCCH. The USS can be defined in a UE-specific manner based on an ID of the UE and a function of various system parameters.

[0192] In the 5G system, the BS can configure the configuration information of the search space for the NRPDCCH to the UE via higher layer signaling (e.g., SIB, MIB, RRC signaling). For example, the BS can configure the following items to the UE at each AL L: the number of candidate NRPDCCHs, the monitoring period of the search space, the monitoring occasion in the symbol within the search space slot, the search space type (CSS or USS), the combination of the DCI format and RNTI to be monitored in the search space, and the index of the CORESET to be monitored for the search space. For example, the parameters for the search space of the NR PDCCH can include the information items listed in Table 6 below.

[0193] [Table 6]

[0194]

[0195]

[0196] According to the configuration information, the BS can configure one or more search space sets to the UE. According to some embodiments, the BS can configure the search space set 1 and the search space set 2 to the UE. For the search space set 1, the UE can be configured to monitor the DCI format A scrambled by the X-RNTI in the CSS; and for the search space set 2, the UE can be configured to monitor the DCI format B scrambled by the Y-RNTI in the USS.

[0197] According to the configuration information, one or more search space sets can exist in the CSS or the USS. For example, the search space set #1 and the search space set #2 can be configured as the CSS, and the search space set #3 and the search space set #4 can be configured as the USS.

[0198] The UE can monitor the following combinations of the DCI format and RNTI in the CSS. However, the combinations are not limited to the examples set forth below.

[0199] - DCI format 0_0 / 1_0, in which the CRC is scrambled by C-RNTI, CS-RNTI, SP-CSI-RNTI, RA-RNTI, TC-RNTI, P-RNTI, Si-RNTI

[0200] - DCI format 2_0, in which the CRC is scrambled by SFI-RNTI

[0201] - DCI format 2_1, in which the CRC is scrambled by INT-RNTI

[0202] - DCI format 2_2, in which the CRC is scrambled by TPC-PUSCH-RNTI, TPC-PUCCH-RNTI

[0203] - DCI format 2_3, where the CRC is scrambled by TPC-SRS-RNTI

[0204] The UE can monitor the following combinations of DCI formats and RNTIs in the USS. However, these combinations are not limited to the examples set out below.

[0205] - DCI format 0_0 / 1_0, where the CRC is scrambled by C-RNTI, CS-RNTI, TC-RNTI

[0206] - DCI format 1_0 / 1_1, where the CRC is scrambled by C-RNTI, CS-RNTI, TC-RNTI

[0207] The above RNTIs can conform to the following definitions and uses.

[0208] Cell RNTI (C-RNTI): used for scheduling UE-specific PDSCH or PUSCH

[0209] Temporary Cell RNTI (TC-RNTI): used for scheduling UE-specific PDSCH

[0210] Configured Scheduling RNTI (CS-RNTI): used for scheduling semi-statically configured UE-specific PDSCH

[0211] Random Access RNTI (RA-RANTI): used for scheduling PDSCH during a random access procedure

[0212] Paging RNTI (P-RNTI): used for scheduling PDSCH transmitting paging information

[0213] System Information RNTI (SI-RNTI): used for scheduling PDSCH transmitting SI

[0214] Interruption RNTI (INT-RNTI): used for notifying whether to puncture PDSCH

[0215] Transmit power control for PUSCH RNTI (TPC-PUSCH-RNTI): used for indicating a power control command for PUSCH

[0216] Transmit power control for PUCCH RNTI (TPC-PUCCH-RNTI): used for indicating a power control command for PUCCH

[0217] Transmit power control for Sounding Reference Signal RNTI (TPC-SRS-RNTI): used for indicating a power control command for SRS

[0218] The above-specified DCI formats can be defined as shown in Table 7 below.

[0219] [Table 7]

[0220]

[0221]

[0222] In 5G, search space at aggregation level L in a CORESET p and a search space set s can be represented by Equation (1) below:

[0223] [Equation 1]

[0224]

[0225] -L: aggregation level

[0226] -n CI : carrier index

[0227] -N CCE，p : total number of CCEs in CORESET p

[0228] -n μ s，f : slot index

[0229] -M (L) p，s，max : number of candidate PDCCHs at aggregation level L

[0230] -m snCI = 0,..., M (L) p，s，max -1: candidate PDCCH index at aggregation level L

[0231] -i = 0,..., L-1

[0232] Y p，-1 = n RNT1 ≠ 0 A0 = 39827, A1 = 39829, A2 = 39839, D = 65537

[0233] -n RNTI : UE ID

[0234] For CSS, the value can correspond to 0.

[0235] For USS, the value can correspond to a value that varies according to a UE ID (C-RNTI or ID configured to the UE by the BS) and a time index.

[0236] Hereinafter, referring to Figure 14 to Figure 20A method of configuring a search space for an NR PDCCH and UE operation when a 5G cell (SCell) performs cross-carrier scheduling on a DSS cell (PCell) after the DSS cell and the 5G cell are aggregated together using CA is described, which is a key feature of the first embodiment. In Figure 14 、 Figure 15 、 Figure 17 and Figure 19 In the example, the relationship of indicating whether a cell to which a CSS and a USS of an NR PDCCH scheduling an NR PDSCH / NR PUSCH is allocated is a PCell or an SCell can be represented by an arrow. In the first embodiment, it is assumed that a 5G UE connects to a DSS cell via initial access to identify the DSS cell as a PCell, and thereafter, a 5G cell is additionally configured as an SCell.

[0237] Figure 14 shows a search space after initial access of a UE in a wireless communication system according to an embodiment of the disclosure. For example, Figure 14 shows an example in which a 5G UE connects to a DSS cell (PCell) through initial access and configures a CSS and a USS within the DSS cell. Figure 14 shows a state in which there is no search space for an SCell due to the SCell not being additionally configured.

[0238] -NR PDCCH search space configuration method 1 (in which a CSS and a USS for an NR PDCCH scheduling a PCell (DSS cell) are separately allocated to the PCell and the SCell, respectively):

[0239] Figure 15 is a diagram showing a method of configuring an NR PDCCH search space in a wireless communication system according to an embodiment of the disclosure. That is, Figure 15 shows an NR PDCCH search space configuration method 1. As described above, since a CSS is used to schedule system information or a paging message, it is desirable that the CSS be allocated to the PCell for operation. Therefore, in the first embodiment, even if an SCell performs cross-carrier scheduling on a PCell, a CSS for the PCell can still be allocated to the PCell (i.e., the DSS cell). On the other hand, since a USS for the PCell can be transferred to the SCell, a problem of a shortage of radio resources for an NR PDCCH in the DSS cell (PCell) can be solved. The configuration of the USS of the PCell transferred to the SCell and its CORESET configuration can follow the configuration of the search space for the SCell and its CORESET configuration, respectively. Therefore, the USS for the PCell no longer exists in the PCell. Figure 16is a flowchart illustrating a method of monitoring an NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure. In other words, Figure 16 A procedure for a UE to monitor an NR PDCCH according to the NR PDDCH search space configuration method 1 is shown. In operation 1601, the UE receives an indication of a CA configuration from a BS. The CA configuration can include a configuration of a SCell to perform cross-carrier scheduling for a PCell. When the UE completes the CA configuration according to the indication of the BS, the UE can perform NR PDCCH monitoring in operation 1602. For example, according to the NR PDCCH search space configuration method 1, the UE can monitor a CSS for the PCell on the PCell and both a USS for the PCell and a USS for the SCell on the SCell. The configuration of the USS for the PCell and its CORESET configuration monitored by the UE on the SCell can follow the configuration of the USS for the SCell and its CORESET configuration, respectively. In a subsequent operation, the UE can receive an NR PDSCH or transmit an NR PUSCH according to scheduling of a successfully received NR PDCCH.

[0240] NR PDCCH search space configuration method 2 in which a CSS and a USS for scheduling an NR PDCCH for a PCell (DSS cell) are not allocated separately but are both allocated to a SCell:

[0241] Figure 17 is a diagram illustrating another method of configuring an NR PDCCH search space in a wireless communication system according to an embodiment of the disclosure. In other words, Figure 17 NR PDCCH search space configuration method 2 is shown. The NR PDCCH search space configuration method 2 can solve the problem of a shortage of radio resources for an NR PDCCH in a DSS cell (PCell) by shifting both a CSS and a USS for the PCell to a SCell, regardless of whether the search space for the PCell is a CSS or a USS. The configuration of the search space of the PCell shifted to the SCell and its CORESET configuration can follow the configuration of the search space for the SCell and its CORESET configuration, respectively. Accordingly, the search space for the PCell can no longer exist in the PCell. Compared to the NR PDCCH search space configuration method 1, the NR PDCCH search space configuration method 2 can more aggressively solve the problem of a shortage of radio resources for an NR PDCCH in a DSS cell (PCell).

[0242] Figure 18is a flowchart illustrating another method of monitoring an NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure. In other words, Figure 18 A procedure for a UE to monitor an NR PDCCH according to the NR PDDCH search space configuration method 2 is shown. In operation 1801, the UE receives an indication of a CA configuration from a BS. The CA configuration can include a configuration of a SCell to perform cross-carrier scheduling for a PCell. When the UE completes the CA configuration according to the indication of the BS, the UE can perform NR PDCCH monitoring in operation 1802. According to the NR PDCCH search space configuration method 2, the UE can monitor a CSS for the PCell, a USS for the PCell, and a USS for the SCell on the SCell. The configuration of the search space for the PCell and the CORESET configuration thereof monitored by the UE on the SCell can follow the configuration of the USS for the SCell and the CORESET configuration thereof, respectively. In a subsequent operation, the UE can receive an NR PDSCH or transmit an NR PUSCH according to scheduling of a successfully received NR PDCCH.

[0243] NR PDCCH search space configuration method 3 (in which a CSS and a USS for scheduling an NR PDCCH for a PCell (DSS cell) are allocated to the PCell, and the USS for scheduling the NR PDCCH for the PCell is additionally allocated to a SCell):

[0244] Figure 19 is a diagram illustrating another method of configuring an NR PDCCH search space in a wireless communication system according to an embodiment of the disclosure. In other words, Figure 19 NR PDCCH search space configuration method 3 is shown. The NR PDCCH search space configuration method 3 can include a method of additionally configuring a USS for a PCell on a SCell while maintaining the same state of a CSS for the PCell and a USS for the PCell before applying a CA. The configuration of the USS for the PCell additionally configured in the SCell and the CORESET configuration thereof can follow the configuration of the search space for the SCell and the CORESET configuration thereof, respectively. In the NR PDCCH search space configuration method 3, the USS for the PCell can be allocated to the PCell and the SCell so that an NR PDCCH for the PCell can be transmitted using a search space of the other cell having a stable radio link even if a radio link of any one of the PCell and the SCell is unstable.

[0245] Figure 20is a flowchart of another method of monitoring NR PDCCH search space in a wireless communication system by a UE according to an embodiment of the disclosure. In other words, Figure 20 A procedure for a UE to monitor NR PDCCH according to NR PDDCH search space configuration method 3 is shown. In operation 2001, the UE receives an indication of CA configuration from the BS. The CA configuration can include a configuration of a SCell to perform cross-carrier scheduling for a PCell. When the UE completes the CA configuration according to the indication of the BS, the UE can perform NR PDCCH monitoring in operation 2002. According to NR PDCCH search space configuration method 3, the UE can monitor a CSS and a USS of the PCell on the PCell, and monitor a USS of the PCell and a USS of the SCell on the SCell. The configuration of the search space for the PCell and its CORESET configuration monitored by the UE on the SCell can follow the configuration of the USS for the SCell and its CORESET configuration, respectively. In a subsequent operation, the UE can receive NR PDSCH or transmit NR PUSCH according to the scheduling of the successfully received NR PDCCH.

[0246] Various modifications can be made to NR PDCCH search space configuration methods 1, 2, and 3. For example, the configuration of the search space for the PCell and its CORESET configuration monitored by the UE on the SCell can be implemented using various methods as described below.

[0247] - Method 1 of configuring the search space and CORESET for the PCell in the SCell: the configuration of the search space for the PCell and its CORESET configuration monitored by the UE on the SCell follow the configuration of the USS for the SCell and its CORESET configuration, respectively, in the same way.

[0248] - Method 2 of configuring the search space and CORESET for the PCell in the SCell: the configuration of the search space for the PCell and its CORESET configuration monitored by the UE on the SCell are offset from the configuration of the USS for the SCell and its CORESET configuration, respectively. The offset can be informed to the UE by the BS via signaling.

[0249] - Method 3 of configuring search space and CORESET for PCell in SCell: independent configuration of the configuration of search space for PCell monitored by UE on SCell and its CORESET configuration from the configuration of USS of SCell and its CORESET configuration, respectively. Thus, the BS informs the UE via signaling of the configuration of search space for PCell monitored by UE on SCell and its associated CORESET configuration.

[0250] - Method 4 of configuring search space and CORESET for PCell in SCell: the BS informs the UE via signaling which of the methods 1, 2 and 3 is used to configure search space and CORESET for PCell in SCell.

[0251] NR PDCCH search space configuration method 2 can be understood as a concept of "PCell change (PCell switch)", in which an existing PCell is switched to SCell and a newly added SCell is switched to PCell by configuring CA to the UE. In this case, from the UL perspective, the UE can transmit PUCCH for transmitting UCI to the BS on the newly switched PCell.

[0252] In NR PDCCH search space configuration methods 1 and 3 in which search space for PCell exists on both PCell and SCell, other procedures related to HARQ operation on NR PDSCH / NR PUSCH for PCell can be required. For example, NR PDCCH for scheduling initial transmission of NR PDSCH on PCell can be mapped to search space for PCell on SCell and transmitted, and NR PDCCH for scheduling retransmission of NR PDSCH on PCell can be mapped to search space for PCell on PCell and transmitted (or vice versa).

[0253] - If the above operation is allowed, the BS can set the HARQ process ID for scheduling initial transmission and the HARQ process ID of NR PDCCH for scheduling retransmission to the same value in the control information of NR PDCCH, thereby informing the UE to schedule the same NR PDSCH (or NR PUSCH).

[0254] - If the above operation is not allowed, the BS maintains the cell to which the NR PDCCH for scheduling the initial transmission has been mapped and transmitted to be the same as the cell to which the NR PDCCH for scheduling the retransmission has been transmitted and mapped. Thus, regardless of the initial transmission or the retransmission, the UE expects the NR PDCCH scheduling the same NR PDSCH (or NR PUSCH) to be transmitted on the same cell, and if they are not transmitted on the same cell, the UE can identify it as an error case.

[0255] In NR PDCCH search space configuration methods 1 and 3 in which the CSS for the PCell and the USS for the PCell exist on the PCell and the SCell, respectively, the following operation can be defined according to whether the NR PDCCH mapped to and transmitted by the USS can also be mapped to the CSS. In addition, when CA is not configured, by allowing the above operation, the amount of radio resources occupied by the search space can be managed to prevent excessive radio resources from being occupied by the search space

[0256] - When the mapping of the NR PDCCH mapped to the USS and transmitted to the CSS is also allowed: the degree of freedom of the NR PDCCH mapping at the BS can be increased.

[0257] - When the mapping of the NR PDCCH mapped to the USS and transmitted to the CSS is not allowed: the complexity of the UE receiving the NR PDCCH can be reduced. To support this type of operation, if the BS configures cross-carrier scheduling for the PCell through CA, the UE expects the NR PDCCH mapped to and transmitted by the USS not to be mapped to the CSS. On the other hand, if the BS does not configure CA or cross-carrier scheduling for the PCell, the UE expects the NR PDCCH mapped to and transmitted by the USS to also be mapped to the CSS.

[0258] <Second Embodiment>

[0259] In the second embodiment, when a DSS cell and a 5G cell are aggregated together using 5G CA and the 5G cell performs cross-carrier scheduling for the DSS cell, the quasi co-location (QCL) relationship of the NR PDCCH is defined for each cell.

[0260] First, a method of configuring a transmission configuration indication (TCI) state for the NR PDCCH (or NR PDCCH DMRS) in the 5G system is described in detail.

[0261] The BS can configure and indicate a TCI state for NR PDCCH (or NR PDCCH DMRS) configuration via suitable signaling. The TCI state is used to inform the QCL relationship between the NR PDCCH (or NR PDCCH DMRS) and another RS port or channel, and when the reference antenna port A (reference RS #A) and another target antenna port B (target RS #B) are QCL, it can be understood that the UE is allowed to apply all or some of the large-scale channel parameters estimated from the antenna port A to the channel estimation from the antenna port B. The QCL can need to associate different parameters depending on the following cases: 1) time tracking affected by average delay and delay spread, 2) frequency tracking affected by Doppler shift and Doppler spread, 3) radio resource management (RRM) affected by average gain, and 4) beam management (BM) affected by spatial parameters. Thus, 5G can support four types of QCL relationships as shown in Table 8 below.

[0262] [Table 8]

[0263] QCL Type Massive Features A Doppler shift, Doppler spread, average delay, delay spread B Doppler shift, Doppler spread C Doppler shift, average delay D Spatial Rx parameters

[0264] The spatial RX parameters can collectively refer to some or all of various parameters such as angle of arrival (AoA), power angular spectrum (PAS) of AoA, angle of departure (AoD), PAS of AoD, transmission / reception channel correlation, transmission / reception beamforming, spatial channel correlation, etc.

[0265] The QCL relationship can be configured to the UE via a TCI state and QCL-Info as an RRC parameter as shown in Table 9 below. Referring to Table 9, the BS can configure one or more TCI states to the UE to inform the UE of up to two QCL relationships (qc1-Type1 and qc1-Type2) of RS (i.e., target RS) containing a reference to a TCI state ID. In this case, each item of QCL information QCL-Info included in the TCL state can include a serving cell index and a bandwidth part (BWP) index of the reference RS indicated by the corresponding QCL information, a type and ID of the reference RS, and a QCL type as shown in Table 8 above.

[0266] [Table 9]

[0267]

[0268]

[0269] A 5G system can support a hierarchical signaling method for dynamic allocation of PDCCH beams. A BS can configure a UE with N TCI states via RRC signaling, some of which can be configured as TCI states for CORESETs. Thereafter, the BS can indicate one of the TCI states for a CORESET to the UE via MAC CE signaling. The UE can receive a PDCCH based on beam information in the TCI state indicated via the MAC CE signaling.

[0270] The TCI indication MAC CE signaling length for NR PDCCH DMRS can be 2 bytes (16 bits), and can include a 1-bit reserved bit, a 5-bit serving cell ID, a 2-bit BWP ID, a 2-bit CORESET ID, and a 6-bit TCI state ID.

[0271] A BS can configure a UE with one or more TCI states for a particular CORESET and activate one of the configured TCI states through a MAC CE activation command. For example, TCI state #0, TCI state #1, and TCI state #2 can be configured as TCI states for CORESET #1, and the BS can send a command to the UE via a MAC CE to activate TCI state #0 (assumed as a TCI state for CORESET #1). The UE can correctly receive a DMRS for the corresponding CORESET based on QCL information in the TCI state activated via the activation command for the TCI state received via the MAC CE.

[0272] For a CORESET with an index set to 0 (CORESET #0), in a case where the UE does not receive a MAC CE activation command for activating a TCI state for CORESET #0, the UE can assume that a DMRS transmitted in CORESET #0 is QCLed with an SS / PBCH block identified during an initial access procedure or during a non-contention-based random access procedure not triggered by a PDCCH order.

[0273] For a CORESET with an index set to a non-0 value (CORESET #X), in a case where the UE is not configured with a TCI state for CORESET #X or is configured with one or more TCI states but does not receive a MAC CE activation command for activating one of the TCI states, the UE can assume that a DMRS transmitted in CORESET #X is QCLed with an SS / PBCH block identified during an initial access procedure.

[0274] Hereinafter, a method of configuring a QCL relationship of an NR PDCCH when a 5G cell (SCell) performs cross-carrier scheduling on a DSS cell (PCell) after the DSS cell and the 5G cell are aggregated together using CA is described, which is a key feature of the second embodiment. According to the first embodiment, a CSS for a PCell and a USS for the PCell can exist on the PCell and the SCell, respectively (i.e., NR PDCCH search space configuration methods 1 and 3), and a difference in QCL characteristics can occur between the PCell and the SCell due to factors such as a difference in frequency therebetween. Therefore, it is necessary to independently operate a QCL configuration for the CSS and a QCL configuration for the USS.

[0275] NR PDCCH QCL configuration method 1 (separate QCL configuration for CSS and USS):

[0276] The NR PDCCH QCL configuration method 1 can operate separate QCL configurations for the CSS and the USS. Therefore, the BS can inform the UE of QCL configuration information for the CSS and QCL configuration information for the USS via signaling. Alternatively, the BS can separately inform the UE of QCL configuration information for a CORESET defining the CSS and QCL configuration information for a CORESET defining the USS through signaling.

[0277] NR PDCCH QCL configuration method 2:

[0278] In the case where the UE does not receive a MAC CE activation command for a TCI state of an NR PDCCH for a specific cell, a QCL to which a QCL of the NR PDCCH is assumed by the UE by default is limited to an available QCL in a corresponding cell in which the NR PDCCH is transmitted. For example, when the UE monitors an NR PDCCH for scheduling an NR PDSCH on a PCell on an SCell, if the UE does not receive a MAC CE activation command for a TCI state of a CORESET to which the NR PDCCH is mapped, the UE can assume that a QCL of the NR PDCCH most recently identified in the SCell is used for a DMRS transmitted in the CORESET. That is, unlike in the existing 5G system, the UE can not determine that the DMRS is QCLed with an SS / PBCH block on the PCell identified by the UE during an initial access procedure.

[0279] <Third embodiment>

[0280] The third embodiment proposes a procedure for configuring a 5G CA between a DSS cell and a 5G cell and performing cross-carrier scheduling from the 5G cell to the DSS cell. Hereinafter, the procedure is described with reference to Figure 21Operations for a UE to be configured with CA are described.

[0281] Figure 21 A procedure for configuring CA in a wireless communication system according to an embodiment of the disclosure is shown.

[0282] Reference Figure 21 In operation 2104, the UE 2100 performs initial access to the BS 2101. During the initial access procedure, the UE can perform cell search to obtain DL time-frequency synchronization with a cell and obtain a cell identity (ID) from a synchronization signal transmitted by the BS. Then, the UE can receive a PBCH using the obtained cell ID and obtain an MIB as basic system information from the PBCH. In addition, the UE can receive a system information (SIB) transmitted by the BS to obtain cell common transmission / reception related control information. The cell common transmission / reception related control information can include random access related control information, paging related control information, common control information on various physical channels, etc. The cell accessed by the UE in operation 2104 can be a PCell.

[0283] In operation 2105, the UE performs random access to the BS by using random access related control information obtained from the system information. The UE that has successfully completed the random access procedure can obtain UL time-frequency with the BS. Then, the UE can transition to a connected state to enable one-to-one communication between the BS and the UE.

[0284] In operation 2106, the UE performs transmission and reception of data to and from the BS through the PCell. The UE can report UE capability information to the BS to inform the BS of whether the UE itself supports a specific function, a maximum allowed value of a function supported by the UE, etc. The UE capability information can include whether the UE supports CA and CA related information. In operation 2106, the UE can perform measurement reporting on a neighboring cell. For example, if a signal strength received from a neighboring cell observed by the UE is greater than a preset threshold, the UE can transmit a measurement report including an ID of the corresponding cell and the received signal strength to the BS. A reference signal for measurement reporting observed by the UE can be an SS / PBCH block or a CSI-RS transmitted by the neighboring cell. The BS can inform the UE of control information for UE measurement reporting through signaling. The control information for UE measurement reporting can include at least some of the following related control information.

[0285] - information on a reference signal of a neighboring cell to be measured, such as whether the reference signal is an SS / PBCH block or a CSI-RS

[0286] - subcarrier spacing of the reference signal

[0287] - Position of the reference signal in time / frequency domain

[0288] - Size of the reference signal in time / frequency domain

[0289] - Whether to report periodically or based on a predetermined event when reporting the measurement result performed by the UE to the BS

[0290] The BS can determine whether to configure CA or instruct handover to another cell to the UE based on the measurement report from the BS. The determination as to whether to configure CA can mean determining whether to combine, for example, a secondary carrier (SCell) with the PCell of the current UE. If the BS determines to configure CA to the UE, the BS can transmit, to the UE, an "RRC reconfiguration" message including relevant information required for SCell addition at the UE in operation 2107. The relevant information required for CA can include carrier bandwidth and center frequency information of the SCell, common control information on a physical channel of the SCell, etc.

[0291] After the process of performing communication with the SCell according to the received "RRC reconfiguration" message is completed, the UE transmits an "RRC reconfiguration complete" message to the BS in operation 2108. From operation 2109, the UE is fully ready to transmit and receive data from the PCell and the SCell of the BS.

[0292] Table 10 below shows the phases such as UE initial access and configuration and release of CA.

[0293] [Table 10]

[0294] Case Description Case 1 Initial access, single cell operation Case 2 SCell addition Case 3 SCell activation Case 4 SCell deactivation Case 5 SCell release Case 6 Handover

[0295] Case 1: Case 1 corresponds to a phase between UE initial access and execution of CA, and the UE supports only self-carrier scheduling operation. Accordingly, the UE determines scheduling for the PCell by monitoring the NR PDCCH transmitted on the PCell.

[0296] Case 2: Case 2 corresponds to an SCell addition phase in which the BS instructs the UE to perform CA by adding a certain SCell. The BS configures the UE for SCell addition via RRC signaling. The RRC signaling for SCell addition includes cross-carrier scheduling configuration information listed in Table 11 below. The RRC signaling for SCell addition is included in the "RRC reconfiguration" message described above. Figure 21

[0297] [Table 11]

[0298] ​

[0299] The BS can inform the UE of whether the PCell is cross-carrier scheduled by the SCell by adding the following signaling to the cross-carrier scheduling configuration information.

[0300] 1) Signaling 1: indicates the PCell ID as index information ("scheduledCellId") of a scheduled cell on which an NR PDSCH / NR PUSCH scheduled by an NR PDCCH is transmitted, or

[0301] 2) Signaling 2: explicitly indicates that the PCell is cross-carrier scheduled by the SCell

[0302] Table 12 shows a specific example of the cross-carrier scheduling configuration information including the above-described signaling 1 or signaling 2. "PcellCrossCarrierScheduling" specified in the following Table 12 can indicate whether the PCell is cross-carrier scheduled by the SCell ("enabled") or indicate whether the PCell is not cross-carrier scheduled by the SCell ("prohibited"). "CIF-InSchedulingCell" information in "PcellCrossCarrierScheduling" can indicate a carrier indicator field (CIF) value to be included in the DCI, and the value is used when the SCell performs cross-carrier scheduling on the PCell.

[0303] [Table 12]

[0304]

[0305] Even when the BS configures that the PCell is cross-carrier scheduled by the SCell, before the SCell is activated, the UE determines scheduling for the PCell by monitoring the NR PDCCH transmitted on the PCell.

[0306] According to an embodiment, in the above-described case 2, whether the PCell is cross-carrier scheduled by the SCell is configured in the RRC signaling for SCell addition, but as a modified example of case 2, a method of changing the PCell existing configuration can also be used. For example, the cross-carrier scheduling configuration information in the above-described Table 11 can be included in the configuration information of the PCell, and whether the PCell is cross-carrier scheduled by the SCell can be updated at the SCell addition stage.

[0307] - Case 3: Case 3 corresponds to the SCell activation phase in which the BS indicates SCell activation to the UE which has completed SCell configuration through SCell addition. When the SCell is activated, the UE monitors NR PDCCH for scheduling the corresponding SCell and performs operations such as SRS transmission, CSI reporting, and PUCCH transmission on the SCell UL. The BS can inform the UE of SCell activation via MAC signaling or physical layer signaling.

[0308] The BS can include in the SCell activation signaling whether the PCell is cross-carrier scheduled by the SCell. If the BS has informed the UE of whether the PCell is cross-carrier scheduled by the SCell in the SCell addition phase, the control information of whether the PCell is cross-carrier scheduled by the SCell can be omitted from the SCell activation signaling.

[0309] When the BS configures the PCell to be cross-carrier scheduled by the SCell and indicates SCell activation, the UE determines scheduling for the PCell by monitoring NR PDCCH transmitted on the SCell (NR PDCCH search space configuration method 2) or by monitoring NR PDCCH transmitted on the PCell and the SCell, respectively (NR PDCCH search space configuration methods 1 and 3).

[0310] - Case 4: Case 4 corresponds to the SCell deactivation phase in which the currently activated SCell becomes a deactivated state. When the SCell is deactivated, the UE does not monitor NR PDCCH for scheduling the corresponding SCell and does not perform operations such as SRS transmission, CSI reporting, and PUCCH transmission in the SCell UL. The BS can inform the UE of SCell deactivation via MAC signaling or physical layer signaling.

[0311] If the BS has configured the PCell to be cross-carrier scheduled by the SCell, the UE determines scheduling for the PCell by monitoring NR PDCCH transmitted on the PCell according to SCell deactivation.

[0312] Case 5: Case 5 corresponds to the SCell release phase in which the BS indicates to the UE to release the current SCell from CA operation. The BS configures the UE of SCell release via RRC signaling. Similar to the SCell deactivation operation, the UE determines scheduling for the PCell by monitoring NR PDCCH transmitted from the PCell.

[0313] - Case 6: It corresponds to a handover phase of changing a serving cell of the UE, in which the BS can indicate to the UE whether to configure CA after the handover, whether to configure cross-carrier scheduling, and whether the SCell is to perform cross-carrier scheduling on the PCell by including it in the handover command.

[0314] As a modified example of Case 2 and Case 3, the following operation can be performed. When the BS informs the UE that the SCell performs cross-carrier scheduling on the PCell in the SCell addition phase, the UE can determine the scheduling on the PCell by monitoring the NR PDCCH transmitted on the SCell (NR PDCCH search space configuration method 2) or by monitoring the NR PDCCH transmitted on the PCell and the SCell, respectively (NR PDCCH search space configuration methods 1 and 3) even without an additional SCell activation command. On the other hand, in the case of monitoring the NR PDCCH for scheduling the SCell, the UE can perform monitoring in the corresponding SCell after the SCell activation, not before the SCell activation.

[0315] <Fourth Embodiment>

[0316] In the procedure for configuring 5G CA between a DSS cell and a 5G cell and performing cross-carrier scheduling from the 5G cell to the DSS cell, the fourth embodiment describes a specific method of monitoring the NR PDCCH by the UE at the time of SCell activation (Case 3) and SCell deactivation (Case 4).

[0317] Hereinafter, referring to Figure 25 and Figure 26 SCell activation operation and SCell deactivation operation are described, respectively.

[0318] As described above, the BS can instruct the UE to perform CA by adding a specific SCell (SCell addition). In addition, the BS can inform the UE of whether the PCell is cross-carrier scheduled by the SCell. In Figure 25 an example, it can be assumed that the BS configures the UE so that the PCell is cross-carrier scheduled by the SCell through the SCell addition operation. In addition, in Figure 25 an example, it can be assumed that the NR PDCCH search space configuration method 1 is used.

[0319] Referring to Figure 25 , the SCell activation state according to the SCell activation command 2504 is described, and on which cell of the PCell 2501 or the SCell 2502 the UE should monitor the search space of the NR PDCCH. In Figure 25In the example, the UE can receive the SCell activation command 2504 from the BS in time slot n 2503. The UE can complete the SCell activation in time slot n+k1 2505, which is after a specific processing time k1 used to process the SCell activation command. Therefore, until time slot n+k1 (i.e., before completing the SCell activation), the UE can monitor the CSS and USS (2506 and 2507) of the PCell on the PCell to obtain the NR PDCCH for scheduling the PCell. Then, after completing the SCell activation in time slot n+k1, the UE can monitor the CSS (2508) of the PCell on the PCell and the USS (2509) of the PCell on the SCell to obtain the NRPDCCH for scheduling the PCell. Additionally, the UE can monitor the USS (2509) of the SCell on the SCell to obtain the NR PDCCH for scheduling the SCell.

[0320] Figure 25 The example can be modified using various operations. For instance, if we assume the use of NR PDCCH search space configuration method 3, then even after slot n+k1 of SCell activation is completed, the UE can monitor the USS of the PCell on the PCell. In other words, after slot n+k1, the UE can monitor the USS of the PCell in both the PCell and SCell.

[0321] exist Figure 25 In the example, according to NR PDCCH search space configuration methods 1 and 3, the UE can monitor the CSS of the PCell on the PCell, regardless of whether the SCell is active.

[0322] In the following text, see references Figure 26 It describes the SCell disable status according to SCell disable command 2604, and the search space on which cell in PCell 2601 or SCell 2602 the UE should monitor the NR PDCCH.

[0323] exist Figure 26 In the example, it can be assumed that the BS configures the UE to have the PCell scheduled across carriers via SCell add operation and SCell activation command. Additionally, it can be assumed that NR PDCCH search space configuration method 1 is used.

[0324] exist Figure 26In an example of FIG. 26, the UE can receive the SCell deactivation command 2604 from the BS in slot n 2603. The UE can complete the SCell deactivation in slot n+k2 2605, which is after a certain processing time k2 for processing the SCell deactivation command. Thus, until slot n+k2 (i.e., before completion of the SCell deactivation), the UE can monitor the CSS of the PCell on the PCell to obtain the NR PDCCH scheduling the PCell (2606). Also, until slot n+k2, the UE can monitor the USS of the PCell on the SCell to obtain the NR PDCCH scheduling the PCell, and monitor the USS of the SCell on the SCell to obtain the NR PDDCH scheduling the SCell (2609). Then, after the slot n+k2 of completion of the SCell deactivation, the UE can monitor the CSS of the PCell on the PCell (2607) and the USS of the PCell on the PCell (2608) to obtain the NR PDCCH scheduling the PCell. Also, the UE can no longer monitor the NR PDCCH for scheduling the SCell.

[0325] Figure 26 The example of FIG. 26 can be modified with various operations. For example, if assuming the NR PDCCH search space configuration method 3 is used, the UE can monitor the USS of the PCell on both the PCell and the SCell before slot n+k2 (i.e., before completion of the SCell deactivation).

[0326] In an example of FIG. 27, the UE can monitor the CSS of the PCell on the PCell, and the USS of the PCell on the SCell, regardless of whether the SCell is deactivated or not, according to the NR PDCCH search space configuration method 1 and 3. Figure 26

[0327] Figure 22 FIG. 28 is a diagram illustrating a transmitter and a receiver of a UE in a wireless communication system according to an embodiment of the disclosure. For convenience of description, devices not directly related to the disclosure are not shown or described.

[0328] Referring to FIG. 28, Figure 22 The UE can include a transmitter 2204 including a UL transmit (TX) processing block 2201, a multiplexer 2202, and a TX radio frequency (RF) block 2203, a receiver 2208 including a DL receive (RX) processing block 2205, a demultiplexer 2206, and a RX RF block 2207, and a controller 2209. The controller 2209 can control the blocks in the receiver 2208 to receive a data channel or a control channel transmitted by the BS as described above, and control the blocks in the transmitter 2204 to transmit a UL signal. ​

[0329] The UL TX processing block 2201 in the transmitter 2204 of the UE can generate a signal to be transmitted by performing processes such as channel coding, modulation, etc. The signal generated by the UL TX processing block 2201 can be multiplexed with other UL signals through the multiplexer 2202, undergo signal processing through the TX RF block 2203, and then be transmitted to the BS.

[0330] The receiver 2208 of the UE can demultiplex signals received from the BS and allocate the resulting signals to the respective DL RX processing blocks. The DL RX processing block 2205 can obtain control information or data transmitted by the BS by performing processes such as demodulation, channel decoding, etc. on the DL signals from the BS. The receiver 2208 of the UE can support the operation of the controller 2209 by providing the output of the DL RX processing block to the controller 2209.

[0331] Figure 23 is a block diagram of a configuration of a UE according to an embodiment of the disclosure.

[0332] Referring to Figure 23 , the UE can include a processor 2330, a transceiver 2310, and a memory 2320. However, the components of the UE are not limited to the above-described examples. For example, the UE can include more or less components than those described above. In addition, the processor 2330, the transceiver 2310, and the memory 2320 can be implemented as a single chip. According to an embodiment, the transceiver 2310 can include Figure 22 the transmitter 2204 and the receiver 2208 of Figure 23 the processor 2330 of Figure 22 the controller 2209.

[0333] According to an embodiment, the processor 2330 can control a series of processes so that the UE can operate according to an embodiment of the disclosure. For example, according to an embodiment of the disclosure, the processor 2330 can control the components of the UE so that the UE performs a transmission and reception method in a wireless communication system to which CA is applied. According to the disclosure, the processor 2330 can include a plurality of processors, and perform the UE transmission and reception method in a wireless communication system to which CA is applied by executing programs stored in the memory 2320.

[0334] The transceiver 2310 can transmit and receive a signal to and from a BS. The signal transmitted to or received from the BS can include control information and data. The transceiver 2310 can include an RF transmitter for up-converting and amplifying a frequency of a signal to be transmitted and an RF receiver for low-noise amplifying and down-converting a frequency of a received signal. However, this is merely an example of the transceiver 2310, and components of the transceiver 2310 are not limited to the RF transmitter and the RF receiver. In addition, the transceiver 2310 can receive a signal via a radio channel and output the signal to the processor 2330, and transmit a signal output from the processor 2330 via a radio channel.

[0335] According to an embodiment, the memory 2320 can store data and programs necessary for UE operations. In addition, the memory 2320 can store control information or data included in a signal transmitted or received by the UE. The memory 2320 can be composed of a storage medium such as read-only memory (ROM), random access memory (RAM), a hard disk, a compact disk (CD)-ROM, and a digital versatile disk (DVD), or a combination thereof. In addition, the memory 2320 can be configured as multiple memories. According to an embodiment, the memory 2320 can store programs for performing transmission and reception operations of the UE in a wireless communication system to which CA is applied according to the embodiments of the disclosure.

[0336] Figure 24 is a block diagram of a configuration of a BS according to an embodiment of the disclosure.

[0337] Referring to Figure 24 , the BS can include a transceiver 2410, a memory 2420, and a processor 2430. However, components of the BS are not limited to the above-described examples. For example, the BS can include more or less components than the above-described ones. In addition, the transceiver 2410, the memory 2420, and the processor 2430 can be implemented as a single chip.

[0338] According to an embodiment, the processor 2430 can control a series of processes so that the BS can operate according to the embodiments of the disclosure. For example, according to the embodiments of the disclosure, the processor 2430 can control components of the BS to perform a method of scheduling a UE in a mobile communication system to which CA is applied. According to the disclosure, the processor 2430 can include a plurality of processors, and perform a method of scheduling a UE in a mobile communication system to which CA is applied by executing programs stored in the memory 2420.

[0339] The transceiver 2410 can transmit and receive a signal to and from a UE. The signal transmitted to or received from the UE can include control information and data. The transceiver 2410 can include an RF transmitter for up-converting and amplifying a signal to be transmitted and an RF receiver for low-noise amplifying and down-converting a signal received. However, this is merely an example of the transceiver 2410, and the components of the transceiver 2410 are not limited to the RF transmitter and the RF receiver. Also, the transceiver 2410 can receive a signal via a radio channel and output the signal to the processor 2430, and transmit a signal output from the processor 2430 via a radio channel.

[0340] According to an embodiment, the memory 2420 can store data and programs necessary for the operation of the BS. Also, the memory 2420 can store control information or data included in a signal transmitted or received by the BS. The memory 2420 can be composed of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination thereof. The memory 2420 can also be configured as multiple memories. According to an embodiment, the memory 2420 can store a program for a method of scheduling a UE in a mobile communication system to which CA is applied according to an embodiment of the disclosure.

[0341] According to an embodiment of the disclosure, the operation method of the UE in the wireless communication system can include receiving, from the BS, configuration information related to CA, wherein the configuration information related to CA includes information related to cross-carrier scheduling between a PCell and an SCell, performing a configuration related to CA based on the configuration information related to CA, and monitoring a CSS of the PCell on the PCell and a USS of the SCell on the SCell based on the performed configuration related to CA, and receiving a PDCCH based on the monitoring.

[0342] According to an embodiment, the operation method of the UE can further include monitoring a USS of the PCell on the PCell based on the performed configuration related to CA.

[0343] According to an embodiment, based on a search space configuration of the USS of the SCell monitored on the SCell, a search space configuration of the USS of the PCell monitored on the SCell is determined, and based on a CORESET configuration of the USS of the SCell monitored on the SCell, a CORESET configuration of the USS of the PCell monitored on the SCell is determined.

[0344] According to embodiments, the operation method of the UE can further include receiving, from the BS, information related to a search space configuration of a USS of a PCell monitored on a SCell via radio resource signal (RRC) signaling, and information related to a CORESET configuration of the USS of the PCell.

[0345] According to embodiments, the information related to cross-carrier scheduling between the PCell and the SCell can include an indicator indicating whether the PCell is cross-carrier scheduled by the SCell, and when the PCell is cross-carrier scheduled by the SCell, the information related to cross-carrier scheduling between the PCell and the SCell can include a carrier indicator field (CIF) value.

[0346] According to embodiments, when the indicator indicates that the PCell is cross-carrier scheduled by the SCell, the operation method of the UE can further include receiving a command message related to SCell activation from the BS, monitoring a CSS of the PCell and a USS of the PCell on the PCell from a slot in which the command message related to SCell activation is received to a slot in which SCell activation is completed, and monitoring the CSS of the PCell on the PCell and at least one of the USS of the PCell or a USS of the SCell on the SCell until a predetermined slot after the slot in which SCell activation is completed.

[0347] According to embodiments, when the indicator indicates that the PCell is cross-carrier scheduled by the SCell, the operation method of the UE can further include receiving a command message related to SCell deactivation from the BS, monitoring the CSS of the PCell on the PCell and at least one of the USS of the PCell or a USS of the SCell on the SCell from a slot in which the command message related to SCell deactivation is received to a slot in which SCell deactivation is completed, and monitoring the CSS of the PCell and the USS of the PCell on the PCell until a predetermined slot after the slot in which SCell deactivation is completed.

[0348] According to embodiments, when the information related to cross-carrier scheduling between the PCell and the SCell does not include an indicator indicating whether the PCell is cross-carrier scheduled by the SCell, the operation method of the UE can further include receiving a SCell activation message including information on whether the PCell is cross-carrier scheduled by the SCell from the BS.

[0349] According to embodiments of the disclosure, a UE in a wireless communication system can include a transceiver and at least one processor. The at least one processor is configured to: receive, from a BS via the transceiver, CA-related configuration information including information related to cross-carrier scheduling between a PCell and an SCell; perform a CA-related configuration based on the CA-related configuration information; monitor a CSS of the PCell on the PCell and a USS of the SCell on the SCell based on the performed CA-related configuration; and receive, via the transceiver, a PDCCH based on the monitoring.

[0350] According to embodiments, the at least one processor can monitor the USS of the PCell on the PCell based on the performed CA-related configuration.

[0351] According to embodiments, a search space configuration of the USS of the PCell monitored on the SCell can be determined based on a search space configuration of the USS of the SCell monitored on the SCell, and a CORESET configuration of the USS of the PCell monitored on the SCell can be determined based on a CORESET configuration of the USS of the SCell monitored on the SCell.

[0352] According to embodiments, the information related to cross-carrier scheduling between the PCell and the SCell can include an indicator indicating whether the PCell is cross-carrier scheduled by the SCell, and when the PCell is cross-carrier scheduled by the SCell, the information related to cross-carrier scheduling between the PCell and the SCell can include a CIF value.

[0353] According to embodiments, when the indicator indicates that the PCell is cross-carrier scheduled by the SCell, the at least one processor can: receive, from the BS via the transceiver, a command message related to SCell activation; monitor the CSS of the PCell and the USS of the PCell on the PCell from a time slot in which the command message related to SCell activation is received to a time slot in which the SCell activation is completed; and monitor the CSS of the PCell on the PCell and at least one of the USS of the PCell or the USS of the SCell on the SCell until a predetermined time slot after the time slot in which the SCell activation is completed.

[0354] According to embodiments, when the indicator indicates that the PCell is cross-carrier scheduled by the SCell, the at least one processor can receive, via the transceiver, a command message related to SCell deactivation from the BS, monitor a CSS of the PCell on the PCell, and monitor a USS of the PCell and a USS of the SCell on the SCell. From a time slot at which the command message related to SCell deactivation is received to a time slot at which SCell deactivation is completed, and monitor the CSS of the PCell on the PCell and the USS of the PCell until a predetermined time slot after the time slot at which SCell deactivation is completed.

[0355] According to embodiments, when the information related to cross-carrier scheduling between the PCell and the SCell does not include the indicator indicating whether the PCell is cross-carrier scheduled by the SCell, the at least one processor can receive, via the transceiver, an SCell activation message from the BS, the SCell activation message including information on whether the PCell is cross-carrier scheduled by the SCell.

[0356] The method according to the embodiments of the disclosure described in the appended claims or the specification can be implemented by hardware, software, or a combination of hardware and software.

[0357] When the method is implemented by software, a computer-readable storage medium storing one or more programs (software modules) can be provided. The one or more programs stored in the computer-readable storage medium can be configured to be executed by one or more processors within the electronic device. At least one program can include instructions that cause the electronic device to execute the methods according to the embodiments of the disclosure described in the claims or the specification.

[0358] The programs (software modules or software) can be stored in RAM, nonvolatile memory including a flash memory, ROM, electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a CD-ROM, a DVD, or other types of optical storage devices, and a magnetic cassette. Alternatively, the programs can be stored in a memory configured as a combination of some or all of the above-mentioned devices. A plurality of such devices can be included in the memory.

[0359] In addition, the programs can be stored in an attached storage device, and the attached storage device can be accessed through a communication network configured by a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), and a storage area network (SAN), or a combination thereof. The storage device can be connected to the device for implementing the embodiments of the disclosure via an external port. In addition, a separate storage device on the communication network can also be connected to the device for implementing the embodiments of the disclosure.

[0360] In the disclosure, the term "computer program product" or "computer readable medium" is used to collectively refer to a medium such as a memory, a hard disk installed in a hard disk drive, a signal, etc. According to the disclosure, the "computer program product" or "computer readable medium" is a means for providing a method for a UE to transmit and receive in a wireless communication system to which CA is applied.

[0361] In specific embodiments of the disclosure, the components included in the disclosure are expressed in singular or plural form according to the specific embodiment presented. However, the singular or plural expression is selected to be appropriate for the situation presented for ease of description, and the disclosure is not limited to the elements in singular or plural form, i.e., the elements expressed in plural form can be configured as a single element, or the elements expressed in singular form can be configured as multiple elements.

[0362] In addition, although embodiments of the disclosure are disclosed in the specification and drawings of the disclosure, and specific terms have been used, they are provided only in the general sense in order to easily describe the technical idea of the disclosure and to facilitate understanding of the disclosure, and are not intended to limit the scope of the disclosure. For example, although the disclosure is based on a scenario in which different systems such as LTE and 5G are combined, it can be generalized and applied to CA within the same system (e.g., 5G). Alternatively, the disclosure can be applied to a scenario in which 5G is combined with a 6G system to be launched in the future. It will be obvious to those of ordinary skill in the art that other modifications based on the technical spirit of the disclosure can be implemented in addition to the embodiments disclosed herein. In addition, these embodiments can be combined with each other to operate if necessary.

[0363] In addition, although specific embodiments have been described in the detailed description of the disclosure, various modifications can be made thereto without departing from the scope of the disclosure. Therefore, the scope of the disclosure should not be limited to the described embodiments, but should be defined by the appended claims and their equivalents.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: receiving, from a base station, a radio resource control (RRC) message including configuration information associated with cross-carrier scheduling; determining whether information indicating that a primary cell (PCell) is scheduled by a secondary cell (SCell) is configured in the configuration information; and monitoring a physical downlink control channel (PDCCH) on the SCell and the PCell in a case that the information indicating that the PCell is scheduled by the SCell is configured, wherein the PDCCH schedules at least one of a physical downlink shared channel (PDSCH) of the PCell and a physical uplink shared channel (PUSCH) of the PCell. The information indicating that the PCell is scheduled by the SCell includes a scheduling cell identifier (ID) and a carrier indicator field (CIF) value corresponding to the SCell.

2. The method of claim 1, wherein, 3.The method of claim 1, further comprising: stopping monitoring the PDCCH on the SCell in a case that the SCell is disabled. 4.The method of claim 1, further comprising: stopping physical uplink control channel (PUCCH) transmission in a case that the SCell is disabled. The configuration information associated with cross-carrier scheduling is included in configuration information of the PCell.

5. The method of claim 1, wherein, 6.A user equipment (UE) in a wireless communication system, comprising: a transceiver; at least one processor coupled with the transceiver and configured to: receive, from a base station, a radio resource control (RRC) message including configuration information associated with cross-carrier scheduling; determine whether information indicating that a primary cell (PCell) is scheduled by a secondary cell (SCell) is configured in the configuration information; and monitor a physical downlink control channel (PDCCH) on the SCell and the PCell in a case that the information indicating that the PCell is scheduled by the SCell is configured, wherein the PDCCH schedules at least one of a physical downlink shared channel (PDSCH) of the PCell and a physical uplink shared channel (PUSCH) of the PCell. The information indicating that the PCell is scheduled by the SCell includes a scheduling cell identifier (ID) and a carrier indicator field (CIF) value corresponding to the SCell. The processor is further configured to:

7. The UE of claim 6, wherein, stop monitoring the PDCCH on the SCell in a case that the SCell is disabled.

8. The UE of claim 6, wherein, The processor is further configured to: stop physical uplink control channel (PUCCH) transmission in a case that the SCell is disabled.

9. The UE of claim 6, wherein, The configuration information associated with cross-carrier scheduling is included in configuration information of the PCell. 11.A method performed by a base station in a wireless communication system, the method comprising:

10. The UE of claim 6, wherein, transmitting, to a user equipment (UE), a radio resource control (RRC) message including configuration information associated with cross-carrier scheduling, wherein the configuration information indicates that a primary cell (PCell) is scheduled by a secondary cell (SCell); and ​ ​ transmitting control information related to the PCell to the UE via a physical downlink control channel (PDCCH) on the SCell and the PCell, wherein the PDCCH schedules at least one of a physical downlink shared channel (PDSCH) of the PCell and a physical uplink shared channel (PUSCH) of the PCell.

12. The method of claim 11, wherein, the information indicating that the PCell is scheduled by the SCell includes a scheduling cell identifier (ID) and a carrier indicator field (CIF) value corresponding to the SCell.

13. A base station in a wireless communication system, comprising: a transceiver; at least one processor coupled with the transceiver and configured to: transmit, to a user equipment (UE), a radio resource control (RRC) message including configuration information associated with cross-carrier scheduling, wherein the configuration information indicates that a primary cell (PCell) is scheduled by a secondary cell (SCell); and transmit control information related to the PCell to the UE via a physical downlink control channel (PDCCH) on the SCell and the PCell, wherein the PDCCH schedules at least one of a physical downlink shared channel (PDSCH) of the PCell and a physical uplink shared channel (PUSCH) of the PCell.

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