Apparatus and method for changing primary cell in wireless communication system

Abstract

The present disclosure relates to an apparatus and a method for changing a primary cell (PCell) in a wireless communication system. An operation method of a terminal may comprise the steps of: performing a random access procedure with a base station; configuring a first cell in the plurality of cells of the base station as a PCell; configuring a second cell among the plurality of cells of the base station as a secondary cell (SCell); receiving an indication to change the PCell to a second cell; and when the second cell is in an inactive state or an active bandwidth portion (BWP) of the terminal in the second cell is dormant, changing the PCell to a third cell different from the second cell, or switching the active BWP and then changing the PCell to the second cell.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly, to an apparatus and method for changing a primary cell (PCell) in a wireless communication system. Background Art

[0002] Wireless communication systems have been widely deployed to provide various types of communication services, such as voice or data. Generally speaking, wireless communication systems are multiple access systems that support communication for multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency division multiple access (SC-FDMA) systems.

[0003] In particular, since a large number of communication devices require a large communication capacity, an enhanced mobile broadband (eMBB) communication technology is being proposed compared to a conventional radio access technology (RAT). In addition, not only a large-scale machine type communication (massive MTC) that provides various services anytime and anywhere by connecting multiple devices and objects is being proposed, but also a communication system that takes into account services / user terminal devices (UEs) that are sensitive to reliability and latency is being proposed. Various technical configurations are proposed for this purpose. Summary of the invention

[0004] Technical issues

[0005] The present disclosure may provide an apparatus and method for dynamically changing a primary cell (PCell) in a wireless communication system.

[0006] The present disclosure may provide an apparatus and method for indicating a PCell change in a wireless communication system.

[0007] The present disclosure may provide an apparatus and method for signaling PCell change-related information in a wireless communication system.

[0008] The present disclosure may provide an apparatus and method for changing a PCell from a first cell to a second cell based on a PCell change indication in a wireless communication system.

[0009] The present disclosure may provide an apparatus and method for transferring at least some functions of a PCell from a first cell to a second cell in a wireless communication system.

[0010] The present disclosure may provide an apparatus and method for performing a PCell change procedure based on a state of a PCell change target cell in a wireless communication system.

[0011] The present disclosure may provide an apparatus and method for changing a bandwidth part (BWP) of a PCell change target cell in a wireless communication system.

[0012] The present disclosure may provide an apparatus and method for preventing a PCell from changing a target cell to inactivation in a wireless communication system.

[0013] The present disclosure may provide an apparatus and method for changing a DRX group configuration based on a PCell change in a wireless communication system.

[0014] The technical objectives to be achieved by the present disclosure are not limited to the contents mentioned above, and those skilled in the art to which the technical configuration of the present disclosure is applied can consider other technical objectives not mentioned therein from the embodiments of the present disclosure to be described below.

[0015] Technical Solution

[0016] As an example of the present disclosure, a method for operating a terminal in a wireless communication system may include: performing a random access process with a base station, configuring a first cell among multiple cells of the base station as a primary cell (PCell), configuring a second cell among multiple cells of the base station as a secondary cell (SCell), receiving an indication to change the PCell to a second cell, and based on the second cell being in an inactive state, and based on the second cell being in an inactive state or an active bandwidth part (BWP) of the terminal in the second cell being dormant, changing the PCell to a third cell different from the second cell, or changing the PCell to the second cell after switching the active BWP.

[0017] As an example of the present disclosure, a method for operating a base station in a wireless communication system may include: performing a random access process with a terminal, configuring a first cell among multiple cells of the base station as a primary cell (PCell) of the terminal, configuring a second cell among multiple cells of the base station as a secondary cell (SCell) of the terminal, and sending an indication to the terminal to change the PCell to the second cell.

[0018] As an example of the present disclosure, a terminal in a wireless communication system may include: a transceiver, and a processor connected to the transceiver, the processor may be configured to: perform a random access process with a base station, configure a first cell among multiple cells of the base station as a primary cell (PCell), configure a second cell among multiple cells of the base station as a secondary cell (SCell), receive an indication to change the PCell to a second cell, and based on the second cell being in an inactive state, and based on the second cell being in an inactive state or the active bandwidth part (BWP) of the terminal in the second cell being dormant, change the PCell to a third cell different from the second cell, or change the PCell to the second cell after switching the active BWP.

[0019] As an example of the present disclosure, a base station in a wireless communication system may include: a transceiver, and a processor connected to the transceiver, and the processor may be configured to: perform a random access process with a terminal, configure a first cell among multiple cells of the base station as a primary cell (PCell) of the terminal, configure a second cell among multiple cells of the base station as a secondary cell (SCell) of the terminal, and send an indication to the terminal to change the PCell to the second cell.

[0020] As an example of the present disclosure, a communication device may include: at least one processor, and at least one computer memory, which is connected to the at least one processor and stores instructions, which indicate operations when the instructions are executed by the at least one processor, and the operations include: performing a random access process with a base station, configuring a first cell among multiple cells of the base station as a primary cell (PCell), configuring a second cell among multiple cells of the base station as a secondary cell (SCell), receiving an indication to change the PCell to a second cell, and based on the second cell being in an inactive state or the active bandwidth part (BWP) of the terminal in the second cell being dormant, changing the PCell to a third cell different from the second cell, or changing the PCell to the second cell after switching the active BWP.

[0021] As an example of the present disclosure, a non-temporary computer-readable medium storing at least one instruction may include at least one instruction executable by a processor, and the at least one instruction may control a device to: perform a random access procedure with a base station, configure a first cell among multiple cells of the base station as a primary cell (PCell), configure a second cell among multiple cells of the base station as a secondary cell (SCell), receive an indication to change the PCell to a second cell, and based on the second cell being in an inactive state or an active bandwidth part (BWP) of a terminal in the second cell being dormant, change the PCell to a third cell different from the second cell, or change the PCell to the second cell after switching the active BWP.

[0022] The above-mentioned aspects of the present disclosure are only a part of exemplary embodiments of the present disclosure, and those skilled in the art can derive and understand various embodiments reflecting the technical features of the present disclosure based on the following detailed description of the present disclosure.

[0023] Beneficial Effects

[0024] As is apparent from the above description, the embodiments of the present disclosure have the following effects.

[0025] According to the present disclosure, the energy consumption of a base station can be reduced.

[0026] Those skilled in the art will appreciate that the effects that can be achieved by the embodiments of the present disclosure are not limited to the above effects, and other beneficial effects of the present disclosure will be more clearly understood from the following detailed description. That is, those skilled in the art can derive unexpected effects according to the embodiments of the present disclosure from the embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An example of a structure of a wireless communication system to which the present disclosure can be applied is illustrated.

[0028] Figure 2 An example of a wireless device applicable to the present disclosure is illustrated.

[0029] Figure 3 The frame structure in a wireless communication system to which the present disclosure can be applied is illustrated.

[0030] Figure 4 An example of a resource grid in a wireless communication system to which the present disclosure can be applied is illustrated.

[0031] Figure 5 An example of a physical resource block in a wireless communication system to which the present disclosure can be applied is illustrated.

[0032] Figure 6 An example of a time slot structure in a wireless communication system to which the present disclosure can be applied is illustrated.

[0033] Figure 7 An example of a physical channel used in a wireless communication system to which the present disclosure can be applied and an example of a general signal transmission and reception method using the physical channel are illustrated.

[0034] Figure 8 An example of mapping physical channels within time slots in a wireless communication system to which the present disclosure can be applied is illustrated.

[0035] Fig. 9 The structure of an SSB (synchronization signal and broadcast channel block) applicable to the present disclosure is illustrated.

[0036] Fig.10 The transmission of SSB applicable to the present disclosure is illustrated.

[0037] Fig.11 Examples of SSB candidate positions applicable to the present disclosure are illustrated.

[0038] Fig.12 An example of downlink time synchronization information applicable to the present disclosure is illustrated.

[0039] Fig.13 An example of a process of obtaining system information applicable to the present disclosure is illustrated.

[0040] Fig.14 An example of multi-beam transmission applicable to the present disclosure is illustrated.

[0041] Fig.15 An example of indication of an actually transmitted SSB applicable to the present disclosure is illustrated.

[0042] Fig.16 An example of a contention-based random access procedure applicable to the present disclosure is illustrated.

[0043] Fig.17 An example of a non-contention-based random access procedure applicable to the present disclosure is illustrated.

[0044] Fig.18 An example of network initial access and communication procedures applicable to the present disclosure is illustrated.

[0045] Fig.19 An example of a DRX cycle applicable to the present disclosure is illustrated.

[0046] Fig. 20 An example of a PCell change indication procedure in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0047] Fig.21 An example of a process of changing a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0048] Fig. 22 An example of a process of transferring at least some functions of a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0049] Fig.23 An example of a process of changing a PCell based on a state of a target cell in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0050] Fig.24 An example of a process of preventing deactivation of a PCell change target cell in a wireless communication system according to an embodiment of the present disclosure is illustrated.

[0051] Fig.25 An example of a process of changing a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated. DETAILED DESCRIPTION

[0052] The embodiments of the present disclosure described below are combinations of elements and features of the present disclosure in a particular form. Unless otherwise mentioned, elements or features may be considered to be selective. Each element or feature may be put into practice without being combined with other elements or features. In addition, embodiments of the present disclosure may be constructed by combining some elements and / or features. The order of operations described in the embodiments of the present disclosure may be rearranged. Some structures or elements of any one embodiment may be included in another embodiment and may be replaced by the corresponding structures or features of another embodiment.

[0053] In the description of the drawings, processes or steps that render the scope of the present disclosure unnecessarily ambiguous will be omitted, and processes or steps that can be understood by those skilled in the art will be omitted.

[0054] Throughout the specification, when a part "includes" or "comprises" a component, this indicates that other components are not excluded and may further be included, unless otherwise specified. The terms "unit", "-or / er" and "module" described in this specification indicate a unit for processing at least one function or operation, which can be implemented by hardware, software or a combination thereof. In addition, "a" or "an", "one", "the", etc. in the context of the present disclosure (more specifically, in the context of the appended claims) may include singular and plural expressions, unless otherwise specified in the specification or unless the context clearly indicates otherwise.

[0055] In the embodiments of the present disclosure, the data transmission and reception relationship between the base station (BS) and the mobile station is mainly described. The BS refers to the terminal node of the network, which directly communicates with the mobile station. The specific operation described as being performed by the BS can be performed by the upper node of the BS.

[0056] That is, it is apparent that in a network composed of a plurality of network nodes including a BS, various operations performed for communication with a mobile station may be performed by the BS or network nodes other than the BS. The term "BS" may be replaced with a fixed station, a Node B, an evolved Node B (eNode B or eNB), an advanced base station (ABS), an access point, etc.

[0057] In an embodiment of the present disclosure, the term terminal may be replaced with UE, mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, advanced mobile station (AMS), etc.

[0058] The transmitter is a fixed and / or mobile node that provides data services or voice services, and the receiver is a fixed and / or mobile node that receives data services or voice services. Therefore, on the uplink (UL), the mobile station can act as a transmitter and the BS can act as a receiver. Similarly, on the downlink (DL), the mobile station can act as a receiver and the BS can act as a transmitter.

[0059] The embodiments of the present disclosure may be supported by at least one of the standard specifications disclosed for wireless access systems including the Institute of Electrical and Electronics Engineers (IEEE) 802.xx system, the 3rd Generation Partnership Project (3GPP) system, the 3GPP Long Term Evolution (LTE) system, the 3GPP Fifth Generation (5G) New Radio (NR) system, and the 3GPP2 system. Specifically, the embodiments of the present disclosure may be supported by the standard specifications 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS36.321, and 3GPP TS 36.331.

[0060] In addition, the embodiments of the present disclosure are applicable to other radio access systems and are not limited to the above-mentioned systems. For example, the embodiments of the present disclosure are applicable to systems applied after the 3GPP 5G NR system and are not limited to a specific system.

[0061] That is, steps or parts that are not described to clarify the technical features of the present disclosure may be supported by those documents. In addition, all terms as proposed herein may be interpreted by standard documents.

[0062] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The detailed description given below with reference to the accompanying drawings is intended to explain exemplary embodiments of the present disclosure, rather than to show the only embodiments that can be implemented according to the present disclosure.

[0063] The following detailed description includes specific terms in order to provide a thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that other terms may be used to replace specific terms without departing from the technical spirit and scope of the present disclosure.

[0064] The embodiments of the present disclosure can be applied to various radio access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc.

[0065] Hereinafter, in order to clarify the following description, the description is based on the 3GPP communication system (e.g., LTE, NR, etc.), but the technical spirit of the present disclosure is not limited thereto. LTE may refer to the technology after 3GPP TS 36.xxx version 8. Specifically, the LTE technology after 3GPP TS 36.xxx version 10 may be referred to as LTE-A, and the LTE technology after 3GPP TS 36.xxx version 13 may be referred to as pre-LTE-A. 3GPP NR may refer to the technology after TS 38.xxx version 15. 3GPP 6G may refer to the technology after TS version 17 and / or version 18. "xxx" may refer to the detailed number of the standard document. LTE / NR / 6G may be collectively referred to as the 3GPP system.

[0066] 3GPP 6G may refer to post-3GPP NR technology based on the 3GPP system. 3GPP 6G may not be limited to a version or a specific TS document, and its name may have a different form from 3GPP 6G. That is, 3GPP 6G may refer to a technology introduced after 3GPP NR, and is not limited to a specific form.

[0067] The following description will mainly focus on the 3GPP NR system, but is not limited thereto, and can be applied to 3GPP 6G. In addition, the content described below may be partially modified to be used in consideration of the 3GPP 6G system, and is not limited to a specific form. However, in the following, for ease of explanation, the 3GPP NR system will be mainly described. For the background technology, terms, abbreviations, etc. used in this disclosure, please refer to the matters described in the standard documents published before this disclosure. For example, standard documents 36.xxx and 38.xxx may be referenced.

[0068] Overall system

[0069] As more and more communication devices require greater communication capacity, the demand for mobile broadband communications that are more enhanced than existing radio access technologies (RATs) is rising. In addition, large-scale machine type communications (MTC) that provide various services anytime and anywhere by connecting multiple devices and things is also one of the main issues worth considering in next-generation communications. In addition, the design of communication systems that consider services / terminals that are sensitive to reliability and latency is also under discussion. Therefore, the introduction of next-generation RATs that consider enhanced mobile broadband communications (eMBB), massive MTC (mMTC), ultra-reliable low-latency communications (URLLC), etc. is under discussion, and for convenience, the corresponding technology is referred to as NR in this disclosure. NR is an expression representing an example of 5G RAT.

[0070] The new RAT system including NR uses an OFDM transmission method or a similar transmission method. The new RAT system may follow OFDM parameters different from those of LTE. Alternatively, the new RAT system may follow the parameter set of the existing LTE / LTE-A as is, but support a wider system bandwidth (e.g., 100MHz). Alternatively, a cell may support multiple parameter sets. In other words, terminals operating according to different parameter sets may coexist in one cell.

[0071] A parameter set corresponds to one subcarrier spacing in the frequency domain. Because the reference subcarrier spacing is scaled by an integer N, different parameter sets can be defined.

[0072] In addition, new RAT systems including 6G may be considered as next generation RATs. New RAT systems including 6G may consider i) very high data speeds per device, ii) a large number of connected devices, iii) global connectivity, iv) very low latency, v) reduced energy consumption of battery-free IoT devices, vi) ultra-high reliability connectivity, and vii) connectivity intelligence with machine learning capabilities, but are not limited thereto. In view of the above, new RAT systems including 6G may consider using the terahertz (THz) band, i.e., a frequency higher than the NR system, for wider bandwidth and higher transmission speeds. RAT systems including 6G may overcome existing limitations by applying artificial intelligence / machine learning (AI / ML), but may not be limited thereto.

[0073] Figure 1 The structure of a wireless communication system to which the present disclosure can be applied is illustrated. Figure 1 , NG-RAN consists of gNBs that provide control plane (RRC) protocol terminations for the NG-Radio Access (NG-RA) user plane (i.e., new access stratum (AS) sublayer / packet data convergence protocol (PDCP) / radio link control (RLC) / MAC / PHY) and UE. The gNBs are interconnected through the Xn interface. In addition, the gNBs are connected to the new generation core (NGC) through the N2 interface. More specifically, the gNB is connected to the access and mobility management function (AMF) through the N2 interface and to the user plane function (UPF) through the N3 interface. Figure 1 It can be based on the structure of the NR system. Figure 1 The structure can be used in the 6G system as it is or by being partially modified, and is not limited to a specific form.

[0074] Figure 2 An example of a wireless device applicable to the present disclosure is illustrated.

[0075] Reference Figure 2The wireless device 200 may send / receive radio signals via various wireless access technologies (e.g., LTE, LTE-A, pre-LTE-A, NR, 5G, 5G-A, 6G). The wireless device 200 may include at least one processor 202 and at least one memory 204, and may further include at least one transceiver 206 and / or at least one antenna 208.

[0076] The processor 202 may be configured to control the memory 204 and / or the transceiver 206 and implement the description, function, process, proposal, method and / or operation flow chart disclosed in this document. For example, the processor 202 may generate a first information / signal by processing the information in the memory 204, and then send a radio signal including the first information / signal through the transceiver 206. In addition, the processor 202 may receive a radio signal including a second information / signal through the transceiver 206, and then store information obtained from the signal processing of the second information / signal in the memory 204. The memory 204 may be connected to the processor 202 and store various information associated with the operation of the processor 202. For example, the memory 204 may store software code including instructions for implementing part or all of the processes controlled by the processor 202 or for implementing the description, function, process, proposal, method and / or operation flow chart disclosed in this document. Here, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement wireless communication technology. The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals through at least one antenna 208. The transceiver 206 may be a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with a radio frequency (RF) unit. In the present disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0077] Hereinafter, the hardware elements of the wireless device 200 will be described in further detail. Although not limited thereto, at least one processor 202 may implement at least one protocol layer (e.g., functional layers such as physical (PHY), medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), radio resource control (RRC), and service data adaptation protocol (SDAP)). At least one processor 202 may generate at least one protocol data unit (PDU) and / or at least one service data unit (SDU) according to the description, function, process, proposal, method, and / or operation flow chart disclosed in this document. At least one processor 202 may generate a message, control information, data, or information according to the description, function, process, proposal, method, and / or operation flow chart disclosed in this document. At least one processor 202 may generate a signal (e.g., a baseband signal) including a PDU, SDU, message, control information, data, or information according to the function, process, proposal, and / or method disclosed in this document, and provide the signal to at least one transceiver 206. At least one processor 202 can receive a signal (e.g., a baseband signal) from at least one transceiver 206 and obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, processes, proposals, methods, and / or operational flow charts disclosed in this document.

[0078] At least one processor 202 may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. At least one processor 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, at least one application specific integrated circuit (ASIC), at least one digital signal processor (DSP), at least one digital signal processing device (DSPD), at least one programmable logic device (PLD), or at least one field programmable gate array (FPGA) may be included in at least one processor 202. The description, functions, processes, proposals, methods, and / or operational flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, processes, or functions. Firmware or software configured to execute the description, functions, processes, proposals, methods, and / or operational flowcharts disclosed in this document may be included in at least one processor 202, or may be stored in at least one memory 204 and executed by at least one processor 202. The description, functions, processes, proposals, methods, and / or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of code, instructions, and / or instruction sets.

[0079] At least one memory 204 may be connected to at least one processor 202 and store various forms of data, signals, messages, information, programs, codes, instructions, and / or instructions. At least one memory 204 may be configured as a read-only memory (ROM), a random access memory (RAM), an erasable programmable read-only memory (EPROM), a flash memory, a hard disk, a register, a cache memory, a computer-readable storage medium, and / or a combination thereof. At least one memory 204 may be located inside and / or outside of at least one processor 202. In addition, at least one memory 204 may be connected to at least one processor 202 via various technologies such as a wired or wireless connection.

[0080] At least one transceiver 206 can send user data, control information, and wireless signals / channels mentioned in the method and / or operation flow chart of this document to at least one other device. At least one transceiver 206 can receive user data, control information, and wireless signals / channels mentioned in the description, function, process, proposal, method, and / or operation flow chart disclosed in this document from at least one other device. For example, at least one transceiver 206 can be connected to at least one processor 202 and send and receive radio signals. For example, at least one processor 202 can control at least one transceiver 206 to send user data, control information, or radio signals to at least one other device. In addition, at least one processor 202 can control at least one transceiver 206 to receive user data, control information, or radio signals from at least one other device. In addition, at least one transceiver 206 can be connected to at least one antenna 208, and at least one transceiver 206 can be configured to send and receive user data, control information, and radio signals / channels mentioned in the description, function, process, proposal, method, and / or operation flow chart disclosed in this document through at least one antenna 208. In this document, at least one antenna may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). At least one transceiver 206 may convert received radio signals / channels from RF band signals to baseband signals in order to facilitate processing of received user data, control information, and radio signals / channels using at least one processor 202. At least one transceiver 206 may convert user data, control information, and radio signals / channels processed using at least one processor 202 from baseband signals to RF band signals. To this end, at least one transceiver 206 may include an (analog) oscillator and / or a filter.

[0081] Reference Figure 2The components of the described wireless device may be referred to by other terms from the functional aspect. For example, the processor 202 may be referred to as a control unit, the transceiver 206 may be referred to as a communication unit, and the memory 204 may be referred to as a storage unit. In some cases, the communication unit may be used to mean at least a part of the processor 202 and the transceiver 206.

[0082] Reference Figure 2 The structure of the wireless device described may be understood as the structure of at least a portion of various devices. As an example, the structure may be at least a portion of various devices (e.g., a robot, a vehicle, an XR device, a handheld device, a home appliance, an IoT device, an AI device / server, etc.). In addition, according to various embodiments, in addition to Figure 2 In addition to the components illustrated in the figure, the device may further include other components.

[0083] For example, the device may be a handheld device such as a smart phone, a smart tablet, a wearable device (e.g., a smart watch, smart glasses), and a handheld computer (e.g., a laptop computer, etc.). In this case, the device may further include at least one of: a power supply unit that supplies power and includes a wired / wireless charging circuit, a battery, etc.; an interface unit that includes at least one port for connecting to another device (e.g., an audio input / output port, a video input / output port); and an input / output unit for inputting and outputting video information / signals, audio information / signals, data, and / or information input from a user.

[0084] For example, the device may be a mobile device such as a mobile robot, a vehicle, a train, a manned / unmanned aerial vehicle (AV), and a ship. In this case, the device may further include at least one of the following: a drive unit including at least one of an engine, a motor, a power train, wheels, brakes, and a steering device of the device; a power supply unit that supplies power and includes a wired / wireless charging circuit, a battery, etc.; a sensor unit that senses state information, environmental information, and user information of the device or the surroundings of the device; an automatic driving unit that performs functions such as route maintenance, speed control, and destination setting; and a position measurement unit that obtains mobile object position information through a global positioning system (GPS) and various sensors.

[0085] For example, the device may be an XR device such as an HMD, a head-up display (HUD) provided in a vehicle, a TV, a smartphone, a wearable device, a home appliance device, a digital signage, a vehicle, and a robot. In this case, the device may further include at least one of: a power supply unit that supplies power and includes a wired / wireless charging circuit, a battery, etc.; an input / output unit that obtains control information and data from the outside and outputs a generated XR object; and a sensor unit that senses state information, environmental information, and user information of the device or the surroundings of the device.

[0086] For example, the device may be a robot, which may be classified according to the purpose or field of use as industrial use, medical use, home use, military use, etc. In this case, the device may further include at least one of: a sensor unit that senses state information, environmental information, and user information of the device or the surroundings of the device; and a drive unit that moves robot joints and performs various other physical operations.

[0087] For example, the device may be an AI device such as a TV, a projector, a smartphone, a PC, a laptop, a digital broadcast terminal, a tablet, a wearable device, a set-top box (STB), a radio, a washing machine, a refrigerator, a digital signage, a robot, and a vehicle. In this case, the device may further include at least one of: an input unit that obtains various types of data from the outside; an output unit that generates an output associated with vision, hearing, or touch; a sensor unit that senses state information, environmental information, and user information of the device or the surroundings of the device; and a training unit that uses learning data to learn a model composed of an artificial neural network. Figure 2 The structure of the wireless device illustrated in the example can be understood as a part of a RAN node (eg, a base station, a DU, a RU, a RRH, etc.). That is, Figure 2 The device illustrated in the example may be a RAN node. In this case, the device may further include a wired transceiver for fronthaul and / or backhaul communication. However, in the case where the fronthaul and / or backhaul communication is based on wireless communication, Figure 2 The at least one transceiver 206 illustrated in FIG. 2 may be used for fronthaul and / or backhaul communications and may not include a wired transceiver.

[0088] Figure 3 The frame structure in a wireless communication system to which the present disclosure can be applied is illustrated.

[0089] The NR system may support multiple parameter sets. Here, the parameter set may be defined by a subcarrier spacing and a cyclic prefix (CP) overhead. Here, multiple subcarrier spacings may be derived by scaling the default (reference) subcarrier spacing by an integer N (or μ). In addition, although it is assumed that very low subcarrier spacing is not used in very high carrier frequencies, the parameter set used herein may be selected independently of the frequency band. In addition, various frame structures according to multiple parameter sets may be supported in the NR system.

[0090] In the following, OFDM parameter sets and frame structures that can be considered in the NR system will be described. The various OFDM parameter sets supported in the NR system can be defined as shown in Table 1 below.

[0091] [Table 1]

[0092] μ <![CDATA[Δf=2 μ ·15[kHz]]]> CP 0 15 normal 1 30 normal 2 60 Normal, Extended 3 120 normal 4 240 normal

[0093] NR supports multiple parameter sets (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15kHz, a wide area of ​​the traditional cellular band is supported, and when the SCS is 30kHz / 60kHz, dense urban areas, lower latency and wider carrier bandwidth are supported, and when the SCS is 60kHz or higher, bandwidths greater than 24.25GHz are supported to overcome phase noise. The NR band is defined as two types of frequency ranges (FR1, FR2). FR1 and FR2 can be configured according to Table 2 below. In addition, FR2 can mean millimeter wave (mmW).

[0094] [Table 2]

[0095] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 410MHz-7125MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0096] Regarding the frame structure in the NR system, the sizes of various fields in the time domain are expressed in T c =1 / (Δf max ·N f ) is expressed in multiples of the time unit. Here, Δf max 480·10 3 Hz, and N f is 4096. Downlink and uplink transmissions are configured (organized) with T f =1 / (Δf max ·N f / 100)T c =10ms duration radio frame. Here, the radio frames are respectively configured with T sf =(Δf max ·N f / 1000)T c=10 subframes of duration of 1ms. In this case, there is one set of frames for uplink and one set of subframes for downlink. In addition, the transmission in uplink frame number i from the terminal should start T earlier than the corresponding downlink frame in the corresponding terminal. TA =(N TA +N TA，offset )T c For the subcarrier spacing configuration μ, the time slots in the subframe are The time slots in a radio frame are numbered in ascending order of A time slot is configured with A continuous OFDM symbol configuration is determined based on the CP Time slot in subframe The start time is the same as the OFDM symbol in the same subframe It is impossible for all terminals to perform transmission and reception at the same time, which means that not all OFDM symbols of a downlink time slot or an uplink time slot are available.

[0097] Table 3 shows the number of OFDM symbols per time slot in a normal CP Number of time slots per radio frame and the number of time slots per subframe And Table 4 represents the number of OFDM symbols per slot, the number of slots per radio frame, and the number of slots per subframe in the extended CP.

[0098] [Table 3]

[0099]

[0100] [Table 4]

[0101]

[0102] Figure 3 This is an example about μ=2 (SCS is 60 kHz), and referring to Table 3, 1 subframe may include 4 slots. Figure 3 1 subframe = {1, 2, 4} slots shown in is an example, and the number of slots that can be included in 1 subframe is as defined in Table 3 or Table 4. In addition, a micro slot may include 2, 4, or 7 symbols or more or less. Regarding physical resources in the NR system, antenna ports, resource grids, resource elements, resource blocks, carrier parts, etc. may be considered. Hereinafter, the physical resources that may be considered in the NR system will be described in detail.

[0103] First, with respect to antenna ports, the antenna ports are defined so that the channel carrying the symbol in the antenna port can be inferred from the channel carrying another symbol in the same antenna port. When the large-scale characteristics of the channel carrying the symbol in one antenna port can be inferred from the channel carrying the symbol in another antenna port, the two antenna ports can be said to be in a quasi-co-location or quasi-co-location (QC / QCL) relationship. In this case, the large-scale characteristics include one or more of delay spread, Doppler spread, frequency offset, average received power, and receive timing.

[0104] In the 6G system, communication can be performed at the above-mentioned THz frequency band higher than the millimeter wave (mmW) frequency, and the same Figure 3 The same frame structure as shown, or a separate frame structure for the 6G system may be used, but is not limited to a specific form.

[0105] Figure 4 A resource grid in a wireless communication system to which the present disclosure can be applied is illustrated.

[0106] Reference Figure 4 , as an illustrative description, the resource grid is configured in the frequency domain with subcarriers, and one subframe is configured with 14·2 μ OFDM symbols, but the resource grid and subframe are not limited to this. In the NR system, the transmitted signal consists of OFDM symbols and One or more resource grids for each subcarrier. Here, represents the maximum transmission bandwidth, which may differ between uplink and downlink and between parameter sets. In this case, one resource grid can be configured for each μ and antenna port p. Each element of the resource grid for μ and antenna port p is called a resource element and is uniquely identified by an index pair (k, l'). Here, is an index in the frequency domain, and refers to the position of a symbol in a subframe. When referring to a resource element in a slot, an index pair (k, l) is used. Here, The resource element (k, l') for μ and antenna port p corresponds to the complex value When there is no risk of confusion or no specific antenna port or parameter set is specified, the indices p and μ can be discarded and the complex value can be or a k，l′ In addition, a resource block (RB) is defined as consecutive subcarriers.

[0107] Point A plays the role of a common reference point for the resource block grid and is obtained as follows.

[0108] -OffsetToPointA for the primary cell (PCell) downlink represents the frequency offset between point A and the lowest subcarrier of the lowest resource block overlapping with the SS / PBCH block used by the terminal for initial cell selection. It is expressed in resource blocks, assuming that the subcarrier spacing for FR1 is 15kHz and the subcarrier spacing for FR2 is 60kHz.

[0109] -absoluteFrequencyPointA represents the frequency location of point A, as expressed in absolute radio frequency channel number (ARFCN).

[0110] For subcarrier spacing configuration μ, the common resource blocks are numbered from 0 upwards in the frequency domain. The center of subcarrier 0 of common resource block 0 for subcarrier spacing configuration μ is the same as "point A". Number of common resource blocks for subcarrier spacing configuration μ in the frequency domain The relationship between and resource element (k, l) is given by the following formula 1.

[0111] [Formula 1]

[0112]

[0113] In equation 1, k is defined relative to point A, so that k=0 corresponds to a subcarrier centered at point A. Physical resource blocks are spaced from 0 to 1 in a bandwidth part (BWP). where i is the number of the BWP. Physical resource block n in BWP i PRB and public resource block n CRB The relationship between is given by the following formula 2.

[0114] [Formula 2]

[0115]

[0116] is the common resource block where the BWP starts relative to common resource block 0.

[0117] Figure 5 The physical resource blocks in the wireless communication system to which the present disclosure can be applied are illustrated. Figure 6 The following illustrates a time slot structure in a wireless communication system to which the present disclosure can be applied.

[0118] Reference Figure 5 and Figure 6 , a slot includes a plurality of symbols in the time domain. For example, for a normal CP, a slot includes 7 symbols, but for an extended CP, a slot includes 6 symbols.

[0119] A carrier includes multiple subcarriers in the frequency domain. A resource block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) is defined as multiple consecutive (physical) resource blocks in the frequency domain and may correspond to a parameter set (e.g., SCS, CP length, etc.). A carrier may include up to N (e.g., 5) BWPs. Data communication may be performed through an activated BWP, and only one BWP may be activated for one terminal. In a resource grid, each element is called a resource element (RE) and may map a complex symbol.

[0120] In the NR system, each component carrier (CC) can support up to 400MHz. If the terminal working in such a wideband CC always operates with the radio frequency (FR) chip for the entire CC turned on, the terminal battery consumption may increase. Alternatively, when considering several application scenarios operating in a wideband CC (e.g., eMBB, URLLC, Mmtc, V2X, etc.), different parameter sets (e.g., subcarrier spacing, etc.) can be supported in each frequency band in the corresponding CC. Alternatively, each terminal may have a different maximum bandwidth capability. In this regard, the base station may instruct the terminal to operate only in part of the bandwidth instead of the total bandwidth of the wideband CC, and for convenience, the corresponding part of the bandwidth is defined as a bandwidth part (BWP). BWP can be configured with continuous RBs on the frequency axis and may correspond to a parameter set (e.g., subcarrier spacing, CP length, slot / microslot duration).

[0121] At the same time, even in one CC configured for the terminal, the base station can configure multiple BWPs. For example, a BWP occupying a relatively small frequency domain can be configured in the PDCCH monitoring time slot, and the PDSCH indicated by the PDCCH can be scheduled in a larger BWP. Alternatively, when the UE is congested in a specific BWP, some terminals can be configured with another BWP for load balancing. Alternatively, considering the frequency domain inter-cell interference elimination between adjacent cells, etc., some middle spectrums of the entire bandwidth can be excluded, and BWPs on two edges can be configured in the same time slot. In other words, the base station can configure at least one DL / UL BWP for a terminal associated with a broadband CC. The base station can activate at least one DL / UL BWP in the configured DL / UL BWP at a specific time (through L1 signaling or MAC control unit (CE) or RRC signaling, etc.). In addition, the base station can indicate switching to another configured DL / UL BWP (through L1 signaling or MAC CE or RRC signaling, etc.). Alternatively, based on a timer, when the timer value expires, it can switch to the determined DL / UL BWP. Here, the activated DL / UL BWP is defined as the active DL / UL BWP. However, when the terminal performs the initial access process or has not yet established an RRC connection, the configuration of the DL / UL BWP may not be received, so the DL / UL BWP assumed by the terminal in this case is defined as the initial active DL / UL BWP.

[0122] Figure 7 Physical channels used in a wireless communication system to which the present disclosure can be applied and a general signal transmission and reception method using the physical channels are illustrated.

[0123] In a wireless communication system, a terminal receives information from a base station via a downlink, and a terminal sends information to a base station via an uplink. The information sent and received by the base station and the terminal includes data and various control information, and there are various physical channels according to the type / purpose of the information they send and receive.

[0124] When the terminal is turned on or newly enters a cell, the terminal performs an initial cell search, which includes synchronization with a base station (S701). To this end, the terminal can synchronize with the base station by receiving a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station, and obtain information such as a cell identifier (ID). Next, the terminal can obtain broadcast information in the cell by receiving a physical broadcast channel (PBCH) from the base station. At the same time, the terminal can check the downlink channel state by receiving a downlink reference signal (DL RS) in the initial cell search step.

[0125] The terminal that has completed the initial cell search can obtain more detailed system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information carried in the PDCCH (S702).

[0126] Meanwhile, if the terminal accesses the base station for the first time or does not have radio resources for signal transmission, the terminal may perform a random access procedure (RACH) on the base station (S703 to S706). To this end, the terminal may send a specific sequence as a preamble through a physical random access channel (PRACH) (S703 and S705), and receive a response message to the preamble through a PDCCH and a corresponding PDSCH (S704 and S706). In the case of a contention-based RACH, a contention resolution process may be additionally performed.

[0127] The terminal that has performed the above process may then perform PDCCH / PDSCH reception (S707) and physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) transmission (S708) as a general uplink / downlink signal transmission process. Specifically, the terminal receives downlink control information (DCI) through PDCCH. Here, DCI includes control information such as resource allocation information for the terminal, and has different formats depending on its purpose of use.

[0128] At the same time, the control information sent by the terminal to the base station through the uplink or received by the terminal from the base station includes downlink / uplink confirmation / non-confirmation (ACK / NACK) signal, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), etc. For the 3GPP LTE system, the terminal can send the above-mentioned CQI / PMI / RI and other control information through PUSCH and / or PUCCH.

[0129] Figure 8 An example of physical channel mapping within a time slot in a wireless communication system applicable to the present disclosure is illustrated.

[0130] Reference Figure 8 ,

[0131] DL control channel, DL or UL data and UL control channel can all be included in one time slot. For example, the first N symbols in the time slot can be used to send the DL control channel (hereinafter referred to as the DL control region), and the last M symbols in the time slot can be used to send the UL control channel (hereinafter referred to as the UL control region). N and M are integers greater than or equal to 0, respectively. The resource area between the DL control region and the UL control region (hereinafter referred to as the data region) can be used to send DL data or send UL data. There may be a time gap between the control region and the data region for DL ​​to UL switching or UL to DL switching. PDCCH can be sent in the DL control region, and PDSCH can be sent in the DL data region. Some symbols in the time slot when switching from DL to UL can be used for time gaps.

[0132] Downlink (DL) physical channel / signal

[0133] (1)PDSCH

[0134] PDSCH carries downlink data (e.g., DL shared channel transport block, DL-SCH TB). TB is encoded in a codeword (CW) and then sent through a scrambling and modulation process. CW includes one or more code blocks (CB). One or more CBs can be combined into a CB group (CBG). Depending on the configuration of the cell, PDSCH can carry up to 2 CWs. Scrambling and modulation are performed according to each CW, and the modulation symbols generated from each CW are mapped to one or more layers. Each layer is precoded, mapped to resources together with DMRS, and sent through the corresponding antenna port. PDSCH can be dynamically scheduled by PDCCH, or semi-statically scheduled (configuration scheduling (CS)) based on a high-level (e.g., RRC and / or layer 1 (L1)) signal (e.g., PDCCH). Therefore, in dynamic scheduling, PDSCH transmission is accompanied by PDCCH, while in CS, PDSCH transmission is not accompanied by PDCCH. CS includes semi-persistent scheduling (SPS).

[0135] (2)PDCCH

[0136] PDCCH carries downlink control information (DCI). For example, PCCCH (i.e., DCI) carries the transmission format and resource allocation of DL-SCH, frequency / time resource allocation information of UL shared channel (SCH), paging information of paging channel (PCH), system information in DL-SCH, frequency / time resource allocation information of high-layer control messages such as random access response (RAR) sent in PDSCH, transmission power control command, activation / release information about SPS / configuration scheduling (CS), etc. Various DCI formats are provided according to the information in DCI.

[0137] Table 5 illustrates a DCI format provided through the PDCCH.

[0138] [Table 5]

[0139]

[0140] DCI format 0_0 can be used to schedule TB-based (or TB-level) PUSCH, and DCI format 0_1 ​​can be used to schedule TB-based (or TB-level) PUSCH or code block group (CBG)-based (or CBG-level) PUSCH. DCI format 1_0 can be used to schedule TB-based (or TB-level) PDSCH, and DCI format 1_1 can be used to schedule TB-based (or TB-level) PDSCH or CBG-based (or CBG-level) PDSCH (DL authorization DCI). DCI format 0_0 / 0_1 can be called UL authorization DCI or UL scheduling information, and DCI format 1_0 / 1_1 can be called DL authorization DCI or UL scheduling information. DCI format 2_0 is used to convey dynamic time slot format information (e.g., dynamic SFI) to the terminal, and DCI format 2_1 is used to convey downlink preemption information to the terminal. DCI format 2_0 and / or DCI format 2_1 can be delivered to terminals within a single group via a group common PDCCH (i.e., a PDCCH delivered to the terminal defined as the group).

[0141] The PDCCH / DCI includes a cyclic redundancy check (CRC), and the CRC is masked / scrambled using various identifiers (e.g., a radio network temporary identifier (RNTI)) according to the owner or purpose of the PDCCH. For example, if the PDCCH is targeted at a specific terminal, the CRC uses a cell-RNTI (C-RNTI) mask. If the PDCCH is related to paging, the CRC uses a paging-RNTI (P-RNTI) mask. If the PDCCH is related to system information (e.g., a system information block (SIB)), the CRC uses a system information RNTI (SI-RNTI) mask. If the PDCCH is related to a random access response, the CRC uses a random access RNTI (RA-RNTI) mask.

[0142] Table 6 illustrates the usage of PDCCH and transport channels according to RNTI. Transport channels are transport channels related to data carried by PDCCH / PUSCH scheduled by PDCCH.

[0143] [Table 6]

[0144]

[0145]

[0146] The modulation scheme of PDCCH is fixed (e.g., Quadrature Phase Shift Keying, QPSK), and one PDCCH consists of 1, 2, 4, 8, or 16 Control Channel Elements (CCEs) depending on the aggregation level (AL). One CCE consists of 6 Resource Element Groups (REGs). One REG is defined by one OFDMA symbol and one (P)RB.

[0147] PDCCH is sent through a control resource set (CORESET). CORESET corresponds to a physical resource / parameter set used to carry PDCCH / DCI within a BWP. For example, CORESET includes a set of REGs with a given parameter set (e.g., SCS, CP length, etc.). CORESET can be configured through system information (e.g., MIB) or terminal-specific (UE-specific) high-level (e.g., RRC) signaling. Examples of parameters / information for configuring CORESET are as follows. One or more CORESETs are configured in a terminal, and multiple CORESETs may overlap in the time domain / frequency domain.

[0148] -controlResourceSetId: indicates the identification information (ID) of CORESET.

[0149] -frequencyDomainResources: indicates the frequency domain resources of CORESET. It is indicated by a bitmap, and each bit corresponds to an RB group (= 6 consecutive RBs). For example, the most significant bit (MSB) of the bitmap corresponds to the first RB group in the BWP. The RB group corresponding to the bit with a bit value of 1 is allocated as the frequency domain resource of CORESET.

[0150] -duration: Indicates the time domain resource of CORESET. It indicates the number of consecutive OFDMA symbols that constitute CORESET. For example, the value of duration is 1 to 3.

[0151] -cce-REG-MappingType: indicates the mapping type from CCE to REG. Both interleaved and non-interleaved types are supported.

[0152] -precoderGranularity: Indicates the precoder granularity in the frequency domain.

[0153] -tci-StatesPDCCH: Information indicating the transmission configuration indication (TCI) state for PDCCH (eg, TCI-StateID). The TCI state is used to provide a quasi co-location (QCL) relationship between a DL RS within an RS set (TCI-state) and a PDCCH DMRS port.

[0154] -tci-PresentInDCI: indicates whether the TCI field is included in the DCI.

[0155] -pdcch-DMRS-ScramblingID: indicates information used to initialize the PDCCH DMRS scrambling sequence.

[0156] In order to receive PDCCH, the terminal can monitor a set of PDCCH candidates in CORESET (e.g., blind decoding). PDCCH candidates represent CCEs monitored by the terminal for PDCCH reception / detection. The terminal can perform PDCCH monitoring in one or more CORESETs of active DL BWPs in each activated cell where PDCCH monitoring is configured. A set of PDCCH candidates monitored by the terminal is defined as a PDCCH search space (SS) set. The SS set can be a common search space (CSS) set or a UE-specific search space (USS) set.

[0157] Table 7 illustrates a PDCCH search space.

[0158] [Table 7]

[0159]

[0160]

[0161] SS sets may be configured via system information (e.g., MIB) or UE-specific high-level (e.g., RRC) signaling. Each DL BWP of a serving cell may have S (e.g., 10) or fewer configured SS sets. For example, the following parameters / information may be provided for each SS set. Each SS set is associated with a CORESET, and each CORESET configuration may be associated with one or more SS sets.

[0162] -searchSpaceId: indicates the ID of the SS set.

[0163] -controlResourceSetId: Indicates the CORESET associated with the SS set.

[0164] -monitoringSlotPeriodicityAndOffset: indicates the PDCCH monitoring periodic slot (in time slot units) and the PDCCH monitoring slot offset (in time slot units).

[0165] -monitoringSymbolsWithinSlot: indicates the first OFDMA symbol for PDCCH monitoring within the slot for which PDCCH monitoring is configured. It is indicated by a bitmap, with each bit corresponding to each OFDMA symbol within the slot. The most significant bit (MSB) of the bitmap corresponds to the first OFDM symbol within the slot. The OFDMA symbol corresponding to the bit with a bit value of 1 corresponds to the first symbol of the CORESET within the slot.

[0166] -nrofCandidates: indicates the number of PDCCH candidates according to AL={1,2,4,8,16} (eg, one of 0, 1, 2, 3, 4, 5, 6, and 8).

[0167] -searchSpaceType: indicates whether the SS type is CSS or USS.

[0168] -DCI format: indicates the DCI format of the PDCCH candidate.

[0169] Based on the CORESET / SS set configuration, the terminal can monitor PDCCH candidates in one or more SS sets in a time slot. The timing (e.g., time / frequency resources) at which PDCCH candidates are to be monitored is defined as a PDCCH (monitoring) opportunity. One or more (monitoring) opportunities can be configured in a time slot.

[0170] Uplink (DL) physical channels / signals

[0171] (1) PUSCH

[0172] The PUSCH carries uplink data (e.g., UL-SCH TB) and / or uplink control information (UCI), and is transmitted based on a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform or a discrete Fourier transform spread OFDM (DFT-s-OFDM) waveform. In the case where the PUSCH is transmitted based on the DFT-s-OFDM waveform, the terminal transmits the PUSCH by applying transform precoding. For example, if transform precoding is not possible (e.g., transform precoding is disabled), the terminal may transmit the PUSCH based on the CP-OFDM waveform, and if transform precoding is possible (e.g., transform precoding is enabled), the terminal may transmit the PUSCH based on the CP-OFDM waveform or the DFT-s-OFDM waveform. The PUSCH may be dynamically scheduled by the PDCCH (dynamic scheduling), or semi-statically scheduled (configuration scheduling (CS)) based on higher layer (e.g., RRC) signaling and / or layer 1 (L1) signaling (e.g., PDCCH). Therefore, in dynamic scheduling, PUSCH transmission is accompanied by PDCCH, while in CS, PUSCH transmission is not accompanied by PDCCH. CS includes type 1 configuration grant (CG) PUSCH transmission and type 2CG PUSCH transmission. In type 1CG, each parameter used for PUSCH transmission is signaled by high-layer signaling. In type 2CG, some parameters used for PUSCH transmission are signaled by high-layer signaling, and the rest are signaled by PDCCH. Basically, in CS, PUSCH transmission is not accompanied by any PDCCH.

[0173] (2) PUCCH

[0174] PUCCH carries uplink control information (UCI). UCI includes the following contents.

[0175] - Scheduling Request (SR): information used to request UL-SCH resources.

[0176] -Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK): A reception response signal for a DL signal (e.g., PDSCH, SPS release PDCCH). The HARQ-ACK response may include a positive ACK (abbreviated as ACK), a negative ACK (NACK), a discontinuous transmission (DTX), or NACK / DTX. HARQ-ACK may be used interchangeably with A / N, ACK / NACK, HARQ-ACK / NACK, etc. HARQ-ACK may be generated in TB units / CBG units.

[0177] - Channel State Information (CSI): Feedback information about DL channels. CSI includes channel quality information (CQI), rank indicator (RI), precoding matrix indicator (PMI), precoding type indicator (PTI), etc.

[0178] [Table 8] illustrates the PUCCH format. The PUCCH format can be classified according to the UCI payload size / transmission length (e.g., the number of symbols constituting the PUCCH resource) / transmission structure. Based on the transmission length, the PUCCH format can be classified into short PUCCH (format 0, 2) and long PUCCH (format 1, 3, 4).

[0179] [Table 8]

[0180]

[0181] (0)PUCCH format 0 (PF0)

[0182] - Supportable UCI payload size: up to K bits (e.g., K=2)

[0183] -Number of OFDM symbols constituting a single PUCCH: 1 to X symbols (e.g., X=2)

[0184] - Transmission structure: consists of only UCI signal, without DM-RS, and the UCI status is transmitted by selecting and transmitting one of multiple sequences.

[0185] (1) PUCCH format 1 (PF1)

[0186] - Supportable UCI payload size: up to K bits (e.g., K=2)

[0187] -Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y=4, Z=14)

[0188] - Transmission structure: DM-RS and UCI are configured in different OFDM symbols in TDM form, and UCI is formed by multiplying a specific sequence by a modulation symbol (e.g., QPSK). By applying cyclic shift (CS) / orthogonal cover code (OCC) to both UCI and DM-RS, CDM (within the same RB) for multiple PUCCH resources (compliant with PUCCH format 1) is supported.

[0189] (2) PUCCH format 2 (PF2)

[0190] - Supportable UCI payload size: more than K bits (e.g., K=2)

[0191] -Number of OFDM symbols constituting a single PUCCH: 1 to X symbols (e.g., X=2)

[0192] - Transmission structure: A structure in which DMRS and UCI are configured / mapped in the same symbol in an FDM form and transmitted by applying IFFT only to the coded UCI bits without applying DTF.

[0193] (3) PUCCH format 3 (PF3)

[0194] - Supportable UCI payload size: more than K bits (e.g., K=2)

[0195] -Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y=4, Z=14)

[0196] - Transmission structure: DMRS and UCI are configured / mapped in different symbols in TDM form and transmitted by applying DFT to the coded UCI bits. Multiplexing is supported in multiple terminals by applying OCC before DFT in UCI and CS (or IFDM mapping) in DMRS

[0197] (4) PUCCH format 4 (PF4)

[0198] - Supportable UCI payload size: more than K bits (e.g., K=2)

[0199] -Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y=4, Z=14)

[0200] - Transmission structure: DMRS and UCI are configured / mapped in different symbols in a TDM form and transmitted without multiplexing between terminals by applying DFT to the coded UCI bits.

[0201] SSB (Synchronization Signal Block) transmission and related operations

[0202] Fig. 9 The structure of an SSB (synchronization signal and broadcast channel block) applicable to the present disclosure is illustrated. Fig. 9 The SSB structure is illustrated. The terminal can perform cell search, system information acquisition, beam alignment for initial access, DL measurement, etc. based on the SSB. The SSB is used interchangeably with the SS / PBCH (Synchronization Signal / Physical Broadcast Channel) block.

[0203] Reference Fig. 9, SSB consists of PSS, SSS and PBCH. SSB consists of 4 consecutive OFDM symbols, and PSS, PBCH, SSS / PBCH and PBCH are sent for each OFDM symbol. PSS and SSS each consist of 1 OFDM symbol and 127 subcarriers, and PBCH consists of 3 OFDM symbols and 576 subcarriers. Polarization coding and QPSK (quadrature phase shift keying) are applied to PBCH. PBCH consists of data RE and DMRS (demodulation reference signal) RE for each OFDM symbol. Each RB has 3 DMRS REs, and there are 3 data REs between DMRS REs.

[0204] Community Search

[0205] Cell search refers to the process by which a terminal acquires time / frequency synchronization of a cell and detects the cell ID (identifier) ​​of the cell (e.g., physical layer cell ID, PCID). PSS is used to detect a cell ID within a cell ID group, and SSS is used to detect a cell ID group. PBCH is used for SSB (time) index detection and half-frame detection.

[0206] The cell search process of the terminal can be summarized as shown in the following [Table 9].

[0207] [Table 9]

[0208]

[0209] There are 336 cell ID groups, and each cell ID group has 3 cell IDs. There are 1008 cell IDs in total, and the cell ID can be defined by [Formula 3].

[0210] [Formula 3]

[0211] in, and

[0212] in, represents the cell ID (e.g., PCID), represents a cell ID group and is provided / obtained through SSS, Indicates a cell ID within a cell ID group and is provided / obtained through the PSS.

[0213] PSS sequence d PSS (n) can be defined as satisfying [Equation 4].

[0214] [Formula 4]

[0215] d Pss (n) = 1-2x(m)

[0216]

[0217] Among them, 0≤n<127, x(i+7)=(x(i+4)+x(i))mod 2, and [x(6) x(5) x(4) x(3) x(2) x(1)x(0)]=[1 1 1 0 1 1 0].

[0218] SSS sequence d SSS (n) can be defined as satisfying [Equation 5].

[0219] [Formula 5]

[0220] d SSS (n)=[1-2x0((n+m0)mod 127)][1-2x1((n+m1)mod 127)]

[0221]

[0222] Among them, 0≤n<127, x0(i+7)=(x0(i+4)+x0(i))mod2, x1(i+7)=(x1(i+1)+x1(i))mod2, [x0(6) x0(5) x0(4) x0(3) x0(2) x0(1) x0(0)]=[0 0 0 0 0 0 1] and [x1(6) x1(5) x1(4) x1(3) x1(2) x1(1) x1(0)]=[0 0 0 0 0 0 1].

[0223] Fig.10 The transmission of SSB applicable to the present disclosure is illustrated. The SSB is transmitted periodically according to the SSB period. The SSB basic period assumed by the terminal during the initial cell search is defined as 20ms. After cell access, the network (e.g., base station) can set the SSB to one of {5ms, 10ms, 20ms, 40ms, 80ms, 160ms}. The SSB burst set is configured at the beginning of the SSB period. The SSB burst set consists of a 5ms time window (i.e., half a frame), and the SSB can be transmitted up to L times within the SSB burst set. Depending on the frequency band of the carrier, the maximum number L of SSB transmissions can be given as follows. A time slot includes at most two SSBs.

[0224] - For the frequency range up to 3 GHz, L = 4

[0225] - For the frequency range of 3 GHz to 6 GHz, L = 8

[0226] - For the frequency range of 6 GHz to 52.6 GHz, L = 64

[0227] The temporal position of a candidate SSB within an SSB burst set may be defined according to the SCS as follows. The temporal position of a candidate SSB is indexed in temporal order from 0 to L-1 within an SSB burst set (ie, half-frame) (SSB index). Candidate SSB and SSB candidate may be used interchangeably in the specification.

[0228] - Case A - 15kHz SCS: The index of the starting symbol of the candidate SSB is given as {2, 8} + 14*n.

[0229] - For operation without shared spectrum channel access (eg, L-band, LCell): If the carrier frequency is 3 GHz or less, n = 0, 1. If the carrier frequency is 3 GHz to 6 GHz, n = 0, 1, 2, 3.

[0230] - For operation with shared spectrum channel access (eg, U-band, UCell): n=0, 1, 2, 3, 4.

[0231] - Case B - 30kHz SCS: The index of the starting symbol of the candidate SSB is given as {4, 8, 16, 20} + 28*n. If the carrier frequency is 3 GHz or less, n = 0. If the carrier frequency is 3 GHz to 6 GHz, n = 0, 1.

[0232] - Case C - 30kHz SCS: The index of the starting symbol of the candidate SSB is given as {2, 8}+14*n.

[0233] - For operation without shared spectrum channel access: (1) For paired spectrum operation, when the carrier frequency is 3 GHz or less, n = 0, 1. When the carrier frequency is within FR1 and greater than 3 GHz, n = 0, 1, 2, 3. (2) For non-paired spectrum operation, when the carrier frequency is 2.4 GHz or less, n = 0, 1. When the carrier frequency is within FR1 and greater than 2.4 GHz, n = 0, 1, 2, 3.

[0234] - For operation without shared spectrum channel access: n=0, 1, 2, 3, 4, 6, 7, 8, 9.

[0235] - Case D - 120kHz SCS: The index of the starting symbol of the candidate SSB is given as {4,8,16,20}+28*n. For carrier frequencies in FR2, n=0,1,2,3,5,6,7,8,10,11,12,13,15,16,17,18.

[0236] - Case E - 240kHz SCS: The indices of the starting symbols of the candidate SSBs are given as {8, 12, 16, 20, 32, 36, 40, 44} + 56*n. For carrier frequencies within FR2, n = 0, 1, 2, 3, 5, 6, 7, 8.

[0237] For operation with shared spectrum channel access, in the case of shared spectrum channel access operation, the terminal assumes that the SSB transmission within the half frame is within the discovery burst transmission window starting from the first symbol of the first time slot within the half frame. The discovery burst transmission window period for each serving cell may be provided to the terminal. If the discovery burst transmission window period is not provided, the terminal regards the discovery burst transmission window period as a half frame. For each serving cell, the terminal assumes that the repetition period of the discovery burst transmission window is the same as the repetition period of the half frame used for SSB reception. The terminal may assume that among the SSBs of the serving cell, the discovery burst transmission window has the same repetition period within the same discovery burst transmission window or across different discovery burst transmission windows. The SSB of the value is in a QCL (quasi co-location) relationship. represents the DM-RS sequence index of the PBCH of the SSB, and (i) provided by ssbPositionQCL-Relationship, or (ii) if ssbPositionQCL-Relationship is not provided, it can be obtained from the MIB (Master Information Block) of the SSB based on [Table 10].

[0238] [Table 10]

[0239]

[0240] ssbSubcarrierSpacingCommon represents the SCS of the RMSI used only for "operation without shared spectrum". The terminal assumes that the number of SSBs sent on the serving cell within the discovery burst transmission window is no greater than The terminal can be based on or to determine the SSB index. Here, i represents the candidate SSB index. Accordingly, more than one candidate SSB may correspond to one SSB index. Candidate SSBs corresponding to the same SSB index are quasi-co-located.

[0241] Fig.11 Examples of SSB candidate positions applicable to the present disclosure are illustrated. Fig.11The case where Q is 4 and ssb-PositionsInBurst is set to "10100000" is illustrated. In this case, only SSBs with SSB (SS / PBCH block) index #0 / #2 can be transmitted. ssb-PositionsInBurst and Q can be used to provide a rate matching mode within a DRS (discovery reference signal) transmission window (or discovery burst transmission window). For example, the terminal can perform rate matching for all SSB candidate position indices that are consistent with the actual transmitted SSB index QCL provided by ssb-PositionsInBurst. Fig.11 In the example, the terminal can perform rate matching on the time / frequency resources of SSB candidate position index 0 / 2 / 4 / 6 / 8 / 10 / 12 / 14 / 16 / 18. Therefore, when receiving a PDSCH scheduled by a PDCCH scrambled with CRC by C-RNTI, MCS-C-RNTI, CS-RNTI, RA-RNTI, MsbB-RNTI, P-RNTI, TC-RNTI (or a PDSCH with SPS (or with CRC) scrambled by SI-RNTI and the system information indicator (i.e., DCI) in the PDCCH is set to 1), if the PDSCH resource allocation overlaps with the PRB including the SSB transmission resources (e.g., SS / PBCH block candidate position index 0 / 2 / 4 / 6 / 8 / 10 / 12 / 14 / 16 / 18), the terminal can assume SSB transmission according to ssb-PositionsInBurst. That is, the terminal may assume that a PRB including SSB transmission resources in an OFDM symbol in which an SSB is transmitted is unavailable for a PDSCH (ie, not mapped).

[0242] Fig.12 An example of downlink time synchronization information applicable to the present disclosure is illustrated. Fig.12 The terminal obtains information about DL time synchronization. The terminal can obtain DL synchronization by detecting SSB. The terminal can identify the structure of the SSB burst set based on the detected SSB index, and can detect the symbol / time slot / half-frame boundary accordingly. The SFN information and half-frame indication information can be used to identify the number of frames / half-frames to which the detected SSB belongs.

[0243] Specifically, the terminal can obtain 10-bit SFN (system frame number) information (s0 to s9) from the PBCH. Among the 10-bit SFN information, 6 bits are obtained from the MIB (master information block) and the remaining 4 bits are obtained from the PBCH TB (transport block).

[0244] Next, the terminal can obtain 1 bit of half-frame indication information (c0). When the carrier frequency is 3 GHz or less, the half-frame indication information can be implicitly signaled using PBCH DMRS. PBCH DMRS indicates 3 bits of information by using one of 8 PBCH DMRS sequences. Therefore, in the case of L=4, among the 3 bits that can be indicated using 8 PBCH DMRS sequences, the remaining 1 bit after indicating the SSB index can be used to indicate the half-frame.

[0245] Finally, the terminal can obtain the SSB index based on the DMRS sequence and the PBCH payload. The SSB candidates are indexed in time order from 0 to L-1 within the SSB burst set (i.e., half-frame). When L=8 or 64, 8 different PBCH DMRS sequences can be used to indicate the 3 bits (b0 to b2) of the least significant bit (LSB) of the SSB index. When L=64, the 3 bits (b3 to b5) of the most significant bit (MSB) of the SSB index are indicated via PBCH. When L=2, 4 different PBCH DMRS sequences can be used to indicate the 2 bits (b0, b1) of the LSB of the SSB index. When L=4, among the 3 bits that can be indicated using 8 PBCH DMRS sequences, the remaining 1 bit after indicating the SSB index can be used to indicate the half frame (b2).

[0246] Obtaining system information

[0247] Fig.13 The process of obtaining system information (SI) is illustrated. The terminal can obtain AS / NAS information through the process of obtaining SI. The process of obtaining SI can be applied to the terminal in RRC_IDLE state, RRC_INACTIVE state and RRC_CONNECTED state.

[0248] SI is divided into a master information block (MIB) and multiple system information blocks (SIBs). In addition to MIB, SI can be called residual minimum system information (RMSI). For reference, further details are described as follows.

[0249] -MIB includes information / parameters related to receiving SystemInformationBlockType1 (SIB1) and is sent via PBCH of SSB.

[0250] -MIB includes information / parameters related to receiving SIB1 and is sent through the PBCH of SSB. For information about MIB, please refer to 3GPP TS 38.331, which may include the following fields.

[0251] -subCarrierSpacingCommon ENUMERATED{scs1 5or60, scs30or120},

[0252] -ssb-SubcarrierOffset INTEGER(0..15),

[0253] -pdcch-ConfigSIB 1 INTEGER (0..255),

[0254] -dmrs-TypeA-Position ENUMERATED{pos2, pos3},

[0255] …

[0256] -spare BIT STRING (SIZE(1))

[0257] Please refer to Table 11 for the description of each field.

[0258] [Table 11]

[0259]

[0260]

[0261] When selecting the initial cell, the terminal assumes that the half frame with SSB is repeated with a periodicity of 20ms. Based on the MIB, the terminal can check whether there is a control resource set (CORESET) (e.g., CORESET#0) for the Type0-PDCCH common search space. If kSSB<=23 (for FR1) or kSSB<=11 (for FR2), the terminal can determine that there is a CORESET for the Type0-PDCCH common search space. If kSSB>23 (for FR1) or kSSB>11 (for FR2), the terminal can determine that there is no CORESET for the Type0-PDCCH common search space. The Type0-PDCCH common search space is a type of PDCCH search space used to send PDCCH scheduling SI messages. When the Type0-PDCCH common search space exists, the terminal can determine (i) multiple consecutive RBs and one or more symbols constituting a CORESET (e.g., CORESET#0) and (ii) a PDCCH opportunity (i.e., a time domain position of PDCCH reception) (e.g., search space #0) based on information in the MIB (e.g., pdcch-ConfigSIB1). When the Type0-PDCCH common search space does not exist, pdcch-ConfigSIB1 provides information about the frequency position where SSB / SIB1 exists and the frequency range where SSB / SIB1 does not exist.

[0262] -SIB1 includes information related to the availability and scheduling (e.g., transmission periodicity, SI window size) of the remaining SIBs (hereinafter referred to as SIBx, where x is an integer greater than or equal to 2). For example, SIB1 may inform whether SIBx is broadcast periodically and whether it is provided on demand when requested by the terminal. If SIBx is provided on demand, SIB1 may include the information required by the terminal to perform the SI request. SIB1 is transmitted via PDSCH, the PDCCH that schedules SIB1 is transmitted via the Type0-PDCCH common search space, and SIB1 is transmitted via the PDSCH indicated by the PDCCH.

[0263] -SIBx is included in the SI message and sent through the PDSCH. Each SI message is sent within a periodic time window (ie, SI window).

[0264] Beam alignment

[0265] Fig.14 An example of multi-beam transmission applicable to the present disclosure is illustrated.

[0266] Beam scanning means that the transmit receive point (TRP) (e.g., base station / cell) changes the beam (direction) of the radio signal according to time (hereinafter, the terms "beam" and "beam direction" can be used interchangeably). SSB can be transmitted periodically by using beam scanning. In this case, the SSB index is implicitly associated with the SSB beam. The SSB beam can be changed in SSB (index) units, or in SSB (index) group units. In the latter case, the SSB beam remains unchanged within the SSB (index) group. That is, the transmission beam direction of the SSB is repeated in multiple consecutive SSBs. In an SSB burst set, the maximum number of transmissions L of the SSB has a value of 4, 8, or 64 depending on the frequency band to which the carrier belongs. Therefore, in an SSB burst set, the maximum number of SSB beams can also be given as follows according to the frequency band of the carrier.

[0267] - For frequency range up to 3 GHz, maximum number of beams = 4

[0268] - For frequency range from 3 GHz to 6 GHz, maximum number of beams = 8

[0269] - For the frequency range from 6 GHz to 52.6 GHz, the maximum number of beams = 64

[0270] *If multi-beam transmission is not applied, there is only one SSB beam.

[0271] When the terminal attempts to initially access the base station, the terminal can align the beam with the base station based on the SSB. For example, after the terminal performs SSB detection, the terminal identifies the best SSB. The terminal can then send a RACH preamble to the base station by using the PRACH resource associated / corresponding to the index (i.e., beam) of the best SSB. Even after initial access, the SSB can be used for beam alignment between the base station and the terminal.

[0272] Channel Measurement and Rate Matching

[0273] Fig.15 An example of an actual transmitted SSB (SSB_tx) indication applicable to the present disclosure is illustrated.

[0274] In an SSB burst set, a maximum of L SSBs can be sent, and the number / position of SSBs actually sent may vary according to each base station / cell. The number / position of SSBs actually sent is used for rate matching and measurement, and information about the SSBs actually sent (e.g., ssb-PositionsInBurst) is indicated as follows.

[0275] -Regarding rate matching: It can be indicated by terminal-specific RRC signaling or RMSI. Terminal-specific RRC signaling includes a complete (e.g., L-length) bitmap in both the frequency range below 6 GHz and above 6 GHz. On the other hand, RMSI includes a complete bitmap below 6 GHz and a compressed bitmap above 6 GHz, as shown in the figure. Specifically, information about the SSB actually transmitted can be indicated by using a group bitmap (8 bits) + an intra-group bitmap (8 bits). Here, the resources (e.g., REs) indicated by terminal-specific RRC signaling or RMSI can be reserved for SSB transmission, and rate matching can be performed on PDSCH / PUSCH by considering the SSB resources.

[0276] -About measurement: In RRC connected mode, the network (e.g., base station) can indicate the SSB set to be measured within the measurement slot. The SSB set can be indicated on a per-frequency layer basis. If there is no indication of an SSB set, a default SSB set is used. The default SSB set includes all SSBs within the measurement slot. The SSB set can be indicated by using a full (e.g., L-length) bitmap of RRC signaling. In RRC idle mode, the default SSB set is used.

[0277] Random Access (RA) Procedure

[0278] General process

[0279] The random access procedure is used for various purposes. For example, the random access procedure can be used for initial access, handover, and UL data transmission triggered by the terminal. The terminal can obtain UL synchronization and UL transmission resources through the random access procedure. The random access procedure is divided into a contention-based procedure and a non-contention-based procedure or a dedicated procedure. The random access procedure and the random access channel (RACH) procedure can be used interchangeably.

[0280] Fig.16 An example of a contention-based random access procedure applicable to the present disclosure is illustrated. Fig.16, the terminal receives information about random access from the base station through system information. Next, when random access is required, the terminal sends a random access preamble (message 1) to the base station (S710). When the base station receives the random access preamble from the terminal, the base station sends a random access response (RAR) message (message 2) to the terminal (S720). Specifically, the scheduling information of the RAR message can be CRC-masked with a random access-RNTI (RA-RNTI) and sent through an L1 / L2 control channel (PDCCH). The PDCCH masked with RA-RNTI can only be sent through a common search space (CSS). When receiving a scheduling signal masked with RA-RNTI, the terminal can receive a RAR message from the PDSCH indicated by the scheduling information. Next, the terminal checks whether the RAR message includes random access response information indicated to the terminal. Whether the RAR message includes random access response information indicated to the terminal can be determined based on whether there is a random access preamble ID (RAID) for the preamble sent to the terminal. The random access response information includes timing offset information for UL synchronization (e.g., timing advance command (TAC)), UL scheduling information (e.g., UL grant), and terminal temporary identification information (e.g., temporary-C-RNTI (TC-RNTI)). If the terminal receives the random access response information, the terminal sends UL shared channel (SCH) data (message 3) through PUSCH according to the UL scheduling information (S730). After receiving the UL-SCH data, the base station sends a contention resolution message (message 4) to the terminal (S740).

[0281] Fig.17 An example of a non-contention-based random access procedure applicable to the present disclosure is illustrated. The non-contention-based random access procedure can be used for a handover procedure or exists when a base station commands a request. The basic procedure is the same as the contention-based random access procedure.

[0282] Reference Fig.17 , the terminal is allocated a dedicated random access preamble from the base station (S810). The dedicated random access preamble indication information (e.g., preamble index) may be included in an RRC message (e.g., a handover command) or received via a PDCCH command. After the random access procedure is initiated, the terminal sends a dedicated random access preamble to the base station (S820). Next, the terminal receives a random access response from the base station (S830), and the random access procedure ends. The random access procedure in the SCell can only be initiated via a PDCCH command.

[0283] In NR, DCI format 1_0 is used to start a non-contention-based random access procedure through a PDCCH command. DCI format 1_0 is used to schedule PDSCH in one DL cell. At the same time, if the cyclic redundancy check (CRC) of DCI format 1_0 is scrambled with C-RNTI and each bit value of the "frequency domain resource assignment" field is 1, DCI format 1_0 is used as a PDCCH command indicating a random access procedure. In this case, the fields of DCI format 1_0 are configured as follows.

[0284] -RA preamble index: 6 bits

[0285] -UL / Supplementary UL (SUL) indicator: 1 bit. If all bit values ​​of the RA preamble index are not 0 and SUL is configured for the terminal in the cell, it indicates the UL carrier that transmits PRACH in the cell. Otherwise, reserved.

[0286] -SSB Index: 6 bits. If all bit values ​​of RA preamble index are not 0, it indicates the SSB used to determine the RACH timing of PRACH transmission. Otherwise, reserved.

[0287] -PRACH Mask Index: 4 bits. If all bit values ​​of RA Preamble Index are not 0, it indicates the RACH opportunity associated with the SSB indicated by SSB Index. Otherwise, reserved.

[0288] - Reserved: 10 bits

[0289] If DCI format 1_0 does not correspond to a PDCCH command, DCI format 1_0 consists of fields for scheduling PDSCH (eg, time domain resource assignment, modulation and coding scheme (MCS), HARQ process number, PDSCH to HARQ feedback timing indicator, etc.).

[0290] Network access and communication process

[0291] The terminal may perform a network access process. For example, when performing network (e.g., base station) access, the terminal may receive system information and configuration information required to perform the process and / or method described / proposed below, and store the information in a memory. The configuration information required for the present disclosure may be received via high-level (e.g., RRC layer, media access control (MAC) layer, etc.) signaling.

[0292] Fig.18An example of network initial access and communication procedures applicable to the present disclosure is illustrated. In NR, physical channels and reference signals can be sent by using beamforming. In the case of supporting beamforming-based signal transmission, there may be a beam management process for aligning the beam between the base station and the terminal. In addition, the signal proposed in the present disclosure can be sent / received by using beamforming. In radio resource control (RRC) idle (IDLE) mode, beam alignment can be performed based on SSB. On the other hand, in RRC-CONNECTED mode, beam alignment can be performed based on CSI-RS (in DL) and SRS (in UL). At the same time, in the case where beamforming-based signal transmission is not supported, the beam-related operations described below can be skipped.

[0293] Reference Fig.18 , a base station (eg, BS) may periodically transmit SSB (S1802). Here, SSB includes PSS / SSS / PBCH. SSB may be transmitted by using beam scanning (refer to Fig.14 ). Next, the base station may send remaining minimum system information (RMSI) and other system information (OSI) (S1804). RMSI may include information required for the terminal to initially access the base station (e.g., PRACH configuration information). At the same time, after performing SSB detection, the terminal identifies the best SSB. Next, the terminal may send a RACH preamble (message 1 (Msg1)) to the base station by using a PRACH resource associated / corresponding to the index (i.e., beam) of the best SSB (S1806). The beam direction of the RACH preamble is associated with the PRACH resource. The association between the PRACH resource (and / or RACH preamble) and the SSB (index) may be configured by system information (e.g., RMSI). Next, as part of the RACH process, the base station may send a random access response (Msg2) as a response to the RACH preamble (S1808), the terminal may send Msg3 (e.g., RRC connection request) by using the UL grant in the RAR (S1810), and the base station may send a contention resolution message (Msg4) (S1812). Msg4 may include RRC connection setup.

[0294] When the RRC connection between the base station and the terminal is configured through the RACH process, subsequent beam alignment can be performed based on SSB / CSI-RS (in DL) and SRS (in UL). For example, the terminal can receive SSB / CSI-RS (S1814). SSB / CSI-RS can be used for the terminal to generate a beam / CSI report. At the same time, the base station can request a beam / CSI report from the terminal through DCI (S1816). In this case, the terminal can generate a beam / CSI report based on SSB / CSI-RS and send the generated beam / CSI report to the base station through PUSCH / PUCCH (S1818). The beam / CSI report may include beam measurement results, information about preferred beams, etc. The base station and the terminal can switch beams based on the beam / CSI report (S1820a and S1820b).

[0295] Next, the terminal and the base station may perform the process and / or method described below. For example, based on the configuration information obtained from the network access process (e.g., the system information acquisition process, the RRC connection process through the RACH, etc.), the terminal and the base station may process the information present in the memory (as proposed in the present disclosure), and send a radio signal or process and store a received radio signal. Here, the radio signal may include at least one of the PDCCH, PDSCH, and reference signal (RS) in the downlink, and at least one of the PUCCH, PUSCH, and SRS in the uplink.

[0296] Discontinuous Reception (DRX) Operation

[0297] The terminal can perform DRX operation. A terminal configured with DRX can reduce power consumption by discontinuously receiving DL signals. DRX can be performed in the radio resource control (RRC)_IDLE state, the RRC_INACTIVE state, and the RRC_CONNECTED state. In the RRC_IDLE state and the RRC_INACTIVE state, DRX is used to discontinuously receive paging signals. The following will describe DRX performed in the RRC_CONNECTED state (RRC_CONNECTED DRX).

[0298] Fig.19 An example of a DRX cycle applicable to the present disclosure (RRC_CONNECTED state) is illustrated.

[0299] Reference Fig.19, the DRX cycle consists of an on duration and an opportunity for DRX. The DRX cycle defines the time interval at which the on duration is periodically repeated. The on duration represents the time slot in which the terminal performs monitoring to receive the PDCCH. When DRX is configured, the terminal performs PDCCH monitoring during the on duration. If the PDCCH is successfully detected during the PDCCH monitoring, the terminal operates the inactive timer and maintains the awake state. On the other hand, if the PDCCH is not successfully detected during the PDCCH monitoring, the terminal enters a sleep state after the on duration. Therefore, in the case where DRX is configured, when the above-mentioned / proposed process and / or method is performed, PDCCH monitoring / reception can be performed discontinuously in the time domain. For example, in the case where DRX is configured, the PDCCH reception opportunity (e.g., a time slot with a PDCCH search space) in the present disclosure can be configured discontinuously according to the DRX configuration. On the other hand, in the case where DRX is not configured, when the above-mentioned / proposed process and / or method is performed, PDCCH monitoring / reception can be performed continuously in the time domain. For example, when DRX is not configured, the PDCCH reception opportunities (eg, time slots with PDCCH search spaces) in the present disclosure may be configured continuously. Meanwhile, regardless of whether DRX is configured, PDCCH monitoring may be limited to time slots configured as measurement gaps.

[0300] Table 12 shows the terminal process related to DRX (RRC_CONNECTED state). Referring to Table 12, DRX configuration information is received through high-layer (e.g., RRC) signaling, and DRX ON / OFF is controlled by the DRX command of the MAC layer. If DRX is configured, such as Fig.19 As shown, when executing the process and / or method described / proposed in the present disclosure, the terminal may not continuously perform PDCCH monitoring.

[0301] [Table 12]

[0302]

[0303] Here, MAC-CellGroupConfig includes configuration information required to configure the medium access control (MAC) parameters of the cell group. MAC-CellGroupConfig may also include configuration information related to DRX. For example, MAC-CellGroupConfig may include the following information defining DRX.

[0304] -drx-OnDurationTimer value: defines the length of the start interval of the DRX cycle.

[0305] -drx-InactivityTimer value: defines the length of the time interval that the terminal stays awake after detecting a PDCCH opportunity indicating a PDCCH for initial UL or DL ​​data.

[0306] -drx-HARQ-RTT-TimerDL value: defines the length of the maximum time interval after receiving a DL initial transmission until a DL retransmission is received.

[0307] -drx-HARQ-RTT-TimerDL value: defines the length of the maximum time interval after receiving the UL initial transmission grant until receiving the UL retransmission grant.

[0308] -drx-LongCycleStartOffset: defines the time length and starting point of the DRX cycle.

[0309] -drx-ShortCycle (optional): defines the length of the short DRX cycle.

[0310] Here, if any one of drx-OnDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerDL is running, the terminal remains awake and performs PDCCH monitoring at each PDCCH opportunity.

[0311] Specific embodiments of the present disclosure

[0312] The present disclosure relates to dynamically changing a primary cell (PCell) in a wireless communication system, and proposes a technology for changing a PCell based on a PCell change-related indication. Specifically, the present disclosure describes a process of changing a PCell and various implementations related to the PCell change.

[0313] Energy saving of base stations can contribute to building environmentally friendly networks by reducing carbon emissions and reducing the operating expenses (OPEX) of communication service providers. Therefore, energy saving of base stations is an important consideration in wireless communication systems including 3GPP. In particular, with the introduction of 5G, which requires high transmission rates, base stations need to have more antennas and provide services through wider bandwidths and wider frequency bands. Therefore, according to a study, the energy cost of base stations has reached about 20% of the total OPEX. As base station energy saving has received more attention than ever before, 3GPP NR Release 18 approved a new study item (SI) called "Network Energy Saving Research".

[0314] Specifically, enhancement techniques are being considered to improve energy-saving capabilities (i.e., network energy saving) from the perspective of transmission and reception of base stations. For example, through one or more network energy-saving techniques, the currently considered methods aim to achieve dynamic and / or semi-static efficient operation, and with potential user equipment support and feedback, and to achieve finer-grained adaptation of transmission and / or reception in the time, frequency, space, and power domains using potential UE support information.

[0315] For NES, the base station can control on / off during a predetermined duration on the time axis, control the transmit / receive resources used for UE common or UE specific signals / channels, change the frequency axis resource amount, control the transmit power, or operate the antenna port or transmit receive point (TRP) on / off technology in the spatial domain. Hereinafter, in the present disclosure, the state of applying the above-mentioned NES related technology (hereinafter referred to as "NES technology") will be referred to as NES mode or NES state. Hereinafter, in the present disclosure, according to method 1, the base station can notify the terminal whether to apply each NEX technology or which NES technology to apply according to each NEX technology group. Alternatively, according to method 2, the base station can configure the NES technology or NES technology group corresponding to each code point of a specific indicator (e.g., an indicator indicated by DCI or MAC CE, an indicator configured by high-level signaling).

[0316] In method 1, when at least one NES technology is applied, the terminal may define the corresponding state as NES mode or NES state. Alternatively, according to the NES technology applied, the terminal may define different NES modes or different NES states. In method 2, the terminal may define the corresponding state according to the NES technology associated with the indicator. For example, when a 1-bit indicator is used, no NES technology is associated with "0", one or more NES technologies are associated with "1", and if an indicator with a value of 1 is received, the terminal may define the state as NES mode or NES state. As another example, when a 2-bit indicator is used, no NES technology is associated with "00", one or more NES technology_A is associated with "01", one or more NES technology_B is associated with "10", and one or more NES technology_C is associated with "11", and if an indicator with a code point other than "00" is received, the terminal may define the state as NES mode or NES state. Here, if "01" is received, the terminal defines NES state #1, if "10" is received, the terminal defines NES state #2, and if "11" is received, the terminal defines NES state #3, so the terminal can identify whether each code point is a NES state or corresponds to which NES state.

[0317] At the same time, the base station can operate multiple frequency bands and / or multiple carriers (or service cells). Therefore, the service cell corresponding to frequency F1 can be operated as the PCell of the first terminal (UE#1), and the service cell corresponding to frequency F2 can be operated as the PCell of the second terminal (UE#2). In this case, in order to operate these two service cells as PCells, the base station should periodically send SSB and / or SIB1 through F1 and F2. However, when the first terminal (UE#1) and the second terminal (UE#2) have no data to send and / or receive or only a small amount of data to send and / or receive, operating only one of the service cells corresponding to F1 or F2 may be advantageous in terms of base station energy saving. That is, if the PCell of the second terminal (UE#2) is changed to a service cell corresponding to F1 instead of F2, the base station can save energy.

[0318] Therefore, the present disclosure proposes a method for dynamically changing PCell. In the following, for ease of description, a serving cell operating as an existing PCell may be referred to as PCell_old, and a serving cell operating as a new PCell under a PCell change instruction of a base station may be referred to as PCell_new.

[0319] According to the embodiments of the present disclosure, Fig. 20 As shown, PCell change related information can be dynamically signaled. Fig. 20 An example of a PCell change indication procedure in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig. 20 Signal exchange between the terminal 2010 and the base station 2020 is illustrated.

[0320] Reference Fig. 20 In step S2001, the base station 2020 sends indication information related to the PCell change to the terminal 2010. For example, the base station 2020 may dynamically send the indication information related to the PCell change through DCI or MAC CE.

[0321] In step S2003, the terminal 2010 changes the PCell based on the indication information related to the PCell change. That is, the terminal 2010 can change the PCell from PCell_old to PCell_new, and perform at least some of the functions or operations performed in the existing PCell_old in PCell_new. According to an embodiment, the at least some functions may include at least one of the following items: a function of monitoring the PDCCH in the CCS set, a function related to the random access process, or a PUCCH transmission function. For example, by changing the PCell from PCell_old to PCell_new, the terminal 2010 may not monitor the PDCCH configured to be monitored in the CSS set of PCell_old, but monitor the PDCCH configured to be monitored in the CSS set of PCell_new.

[0322] [Implementation #1] Example of Signaling PCell Change

[0323] The base station may indicate the PCell change to the terminal via DCI or MAC CE. The DCI or MAC CE indicating the PCell change may be delivered in a UE-specific, UE group common, or cell-specific manner. The DCI may be delivered after being scrambled using an identifier (e.g., a radio network temporary identifier (RNTI)) configured in a UE-specific, UE group common, or cell-specific manner. The MAC CE may be delivered via a PDSCH scheduled in the DCI, which is scrambled using an identifier configured in a UE-specific, UE group common, or cell-specific manner. According to an embodiment, the bit position indicating the PCell change in the MAC CE may be pre-configured.

[0324] Fig.21 An example of a process of changing a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig.21 A method for operating a terminal is illustrated.

[0325] Reference Fig.21 In step S2101, the terminal configures the PCell and the SCell and performs communication. That is, the terminal can perform a random access process with the base station, configure the initial serving cell of the base station as the PCell for carrier aggregation, and add at least one different serving cell as the SCell. Therefore, the terminal can perform communication by using multiple cells including the PCell and the SCell.

[0326] In step S2103, the terminal receives an indication of a PCell change. That is, the terminal may receive an indication of a PCell change via a DCI or a MAC CE. For example, the PCell change may be indicated by using a DCI indicating a PUCCH cell switch, a PDCCH command, an SPS / CG configuration, or an NES state.

[0327] In step S2105, the terminal performs a PCell change process. That is, the terminal may perform a process of changing the PCell from the first cell to the second cell based on the indication of the PCell change. Here, the second cell may be one of the serving cells of the terminal or not. The process of changing the PCell may include at least one operation for performing at least some of the functions performed in the first cell in the second cell.

[0328] In case of indicating the PCell by using DCI, at least one of the following embodiments may be applied.

[0329] [Implementation #1-1] As described in Table 13 below, the DCI indicating the PUCCH cell switching can be used to indicate a PCell change. As an example, the indicator indicating the PUCCH cell switching can be configured in a DCI format (e.g., DCI format 1_1 or DCI format 1_2). If the indicator is "0", the terminal can send the PUCCH through the PCell, and if the indicator is "1", the terminal can send the PUCCH through the preconfigured PUCCH-sSCell. According to an implementation of the present disclosure, if the PUCCH cell switching indicator configured in the corresponding DCI format is used to indicate the PCell, the terminal can determine the cell in which at least some functions of the PCell are to be performed based on the PUCCH cell switching indicator. For example, if the PUCCH cell switching indicator is "0", the terminal can retain all PCell functions in the existing PCell, and if the PUCCH cell switching indicator is "1", the terminal can perform at least some functions of the PCell in the preconfigured PUCCH-sSCell. Whether the PUCCH cell switching indicator can be used as PCell change indication information can be pre-configured by high-level signaling. Alternatively, the terminal may determine whether the PUCCH cell switching indicator is used as PCell change indication information based on whether the PUCCH cell switching indicator is in the NES state. For example, in the case of the NES state, the terminal may determine that the PUCCH cell switching indicator can be used as PCell change indication information, and perform the PCell change function according to the PUCCH cell switching indicator.

[0330] Table 13 is extracted from TS 38.213v17.3.0 and describes the procedures related to PUCCH cell switching.

[0331] [Table 13]

[0332]

[0333]

[0334] [Implementation #1-2] A PDCCH command can be used to indicate a PCell change. For example, a PDCCH command indicating the start of a random access process can be used to indicate a PCell change. When DCI format 1_0 is scrambled by C-RNTI and the frequency domain resource assignment (FDRA) field is all 1, the random access process can be started by a PDCCH command. As an example, a PCell change can be indicated by a bit (or multiple bits), a code point, or a combination of code points in a specific field of a PDCCH command. For example, a random access preamble index field, a UL / SUL indicator field, a SS / PBCH index field, a PRACH mask index field, or a reserved bit field can be used to indicate a PCell change. In this case, the terminal can receive the PUCCH configuration of the PCell_new to be changed through high-level signaling (e.g., a handover command), and send a PUCCH in PCell_new as a response to the reception of the PDCCH command. That is, in response to the reception of the PDCCH command, the terminal does not send PRACH but sends PUCCH, thereby notifying the base station of the PCell change.

[0335] [Implementation #1-3] If an SPS / CG configuration with a specific index in a PCell or SCell is indicated for activation, a PCell change may be performed. The specific index may be predefined or set by higher layer signaling. For example, the specific index may be predefined as a minimum configuration index or a higher configuration index.

[0336] [Implementation #1-4] If the NES state or the specific NES state is indicated, the PCell change can be performed. Alternatively, if a specific DRX configuration (e.g., cell-specific DTX and / or DRX configuration) is activated among the set multiple DRX configurations (e.g., cell-specific DTX and / or DRX configuration), the PCell change can be performed. When the NES state is indicated, the PCell can be performed. Alternatively, if a switch to a specific BWP is performed in the PCell or SCell, the PCell change can be performed. For example, if a switch from BWP#1 to BWP#2 is performed in the PCell, the existing PCell of the terminal may become PCell_old, and the pre-configured existing SCell may become PCell_new.

[0337] In the above embodiments and the embodiments described below, PCell may be replaced by PSCell. That is, in the present disclosure, PCell may be understood as PSCell, and the embodiments proposed herein may also be applied to the change of PSCell.

[0338] Through the PCell change indication proposed in implementation #1-1 to implementation #1-4, a certain SCell belonging to the SCG can be dynamically changed from PCell to PSCell. In the above implementation, there may be multiple candidate SCells that can be changed to PCell. Here, all service cells except PCell can be included in the candidate SCells, or some service cells can be included in the candidate SCells. Whether each service cell is included in the candidate SCell can be set and / or indicated by the base station. For example, in the process of adding an SCell, it can be indicated whether it is a candidate SCell for PCell change. If multiple candidate SCells are configured, one SCell among the multiple candidate SCells can be indicated by DCI or MAC CE, so that the indicated one SCell is changed to PCell.

[0339] When receiving a DCI or MAC CE indicating a PCell change, the terminal may perform a PCell change operation after a certain time. That is, the terminal delays the application for a certain time after receiving the DCI or MAC CE indicating the PCell change, and then the terminal may perform the PCell operation. For example, after receiving K1 symbols after the DCI or MAC CE indicating the PCell change, the terminal may perform a PCell change operation at the nearest time slot after K1 symbols or at the nearest time slot group boundary after K1 symbols. As another example, after sending K2 milliseconds of HARQ-ACK feedback corresponding to the DCI or MAC CE indicating the PCell change, the terminal may perform a PCell change operation at the nearest time slot after K2 milliseconds or at the nearest time slot group boundary after K2 milliseconds. Here, a certain time (e.g., K1 symbols or K2 milliseconds) for delaying the PCell change operation may be predefined or configured, or configured by a terminal (or UE) capability signaling report. A certain time may be set in units of symbols, time slots, or milliseconds.

[0340] According to an embodiment, a timer value for a PCell change operation may be preset and / or defined. The terminal may operate a timer when the PCell changes from PCell_old to PCell_new, and when the timer value expires, the terminal may change the PCell from PCell_new to PCell_old again.

[0341] [Implementation #2] An example of executing at least some of the functions of the existing PCell when changing the PCell.

[0342] Taking into account the traffic load, PCell can be temporarily changed. That is, as the amount of traffic load changes over time, when the load amount is small, PCell can be temporarily changed from PCell_old to PCell_new, and then returned to the existing PCell_old. In this case, more high-layer signaling may be required to transfer all functions of PCell from PCell_old to PCell_new, and then return the functions to PCell_old. In addition, this may result in increased latency, which may require significant changes in the operation of the terminal. Therefore, if PCell is changed according to the above-mentioned implementation #1, only some of the functions that are performed or supported in PCell_old can be performed in PCell_new. For example, as shown in the following implementations #2-1 to #2-3, at least some of the functions that can be performed in PCell_old can be performed in PCell_new.

[0343] Fig. 22 An example of a process of transferring at least some functions of a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig. 22 A method for operating a terminal is illustrated.

[0344] Reference Fig. 22 In step S2201, the terminal determines that the PCell is changed from the first cell to the second cell. That is, by receiving an indication of the PCell change from the base station, the terminal can determine that the PCell is to be changed from the first cell to the second cell. The indication of the PCell change can be performed by at least one of the signaling described in implementation mode #1.

[0345] In step S2203, the terminal identifies the PCell function to be transferred to the second cell. That is, the terminal can identify at least one PCell function to be performed in the second cell as a new PCell (e.g., PCell_new) from the PCell functions performed in the first cell as an existing PCell (e.g., PCell_old), and / or the PCell function configured to operate in the first cell. The PCell function to be transferred to the second cell can be determined based on a preconfigured rule or an indication of the base station (e.g., a high-layer signaling or an indication based on DCI).

[0346] In step S2205, the terminal performs the identified PCell function in the second cell. That is, by transferring the PCell function from the first cell to the second cell, the terminal can perform the PCell function in the second cell. Here, the terminal can perform the signaling required to transfer the identified PCell function from the first cell to the second cell. Here, the remaining PCell functions other than the identified PCell function can still be performed in the first cell. That is, among the PCell functions operating in the first cell and / or the PCell functions configured to operate in the first cell, the remaining PCell functions other than at least one PCell function transferred to the second cell can be maintained to operate in the first cell. Alternatively, according to another embodiment, the remaining PCell functions other than the identified PCell functions may not be performed in the first cell, and the terminal may not perform signal sending and receiving through the first cell.

[0347] In reference Fig. 22 In the described embodiment, at least one identified function is transferred to the second cell, and the remaining at least one function is provided in the first cell. According to another embodiment, at least one identified function may be transferred to the second cell, some of the remaining at least one function may be provided in the first cell, and the remaining at least one function may be suspended. By suspending at least one function, energy saving efficiency may be improved. Here, the at least one function to be suspended may be predefined or set or indicated by the base station. The at least one function to be suspended may be preconfigured and / or indicated during the carrier aggregation configuration process, or may be set and / or indicated together with an indication of a PCell change. For example, according to an embodiment, a paging function may be suspended.

[0348] As reference Fig. 22 In the described implementation, due to the change of PCell, only some functions can be transferred to PCell_new. Therefore, at least one function transferred can be defined in various ways according to the specific implementation. In addition, at least one function transferred can be predefined or set by the base station or signaled to the terminal. Specifically, the following functions can be transferred to PCell_new.

[0349] [Implementation #2-1] PDCCH monitoring function

[0350] In the PDCCH monitoring performed or configured to be performed in PCell_old, all or some of the monitoring can be performed in PCell_new. Specifically, the PDCCH monitoring function for a specific type of CCS set, a specific DCI format and / or a specific SS set index (e.g., SS set index 0) can be controlled to be performed in PCell_new instead of in PCell_old. Here, the specific type of CCS set may include at least one of the following items defined in TS 38.213: Type0-PDCCH CSS set, Type0A-PDCCH CSS set, Type0B-PDCCH CSS set, Type1-PDCCH CSS set, Type1A-PDCCH CSS set, Type2-PDCCH CSS set, Type2A-PDCCH CSS set or Type3-PDCCH CSS set. Alternatively, the specific DCI format may include at least one of the following items: DCI format 0_0, DCI format 1_0, DCI format 2_X or DCI format 4_X.

[0351] Among the PDCCH monitoring performed or configured to be performed in PCell_old, some PDCCH monitoring to be performed in PCell_new instead of PCell_old can be predefined or set by high-level signaling. For example, the CSS set type, DCI format and SS set index for PDCCH monitoring that can be performed in PCell_new can be predefined or set by high-level signaling.

[0352] According to alternative implementation #2-1-1, when PDCCH monitoring for a specific CSS set is performed in PCell_new, settings related to PDCCH monitoring for a specific CSS set may be set according to each serving cell. Settings related to PDCCH monitoring for a specific CSS set may include settings for a monitoring mode for a corresponding CCS set, a CORESET index, and / or the number of PDCCH candidates for each aggregation level. Here, the monitoring mode for the corresponding CSS set may include at least one of periodicity, offset, and symbol position of the PDCCH opportunity within a time slot.

[0353] According to alternative implementation #2-1-2, when PDCCH monitoring for a specific CSS set is performed in PCell_new, PDCCH monitoring related settings for the specific CSS set preconfigured in PCell_old can be inherited to PCell_new.

[0354] In alternative implementation #2-1-2, in order to minimize the ambiguity that may arise due to the application of the monitoring mode, a constraint may be applied that PCell_new and PCell_old should have the same SCS and / or duplex mode (e.g., FDD or TDD). Alternatively, regardless of the alternative implementation, for the target SCell to be changed to PCell, a constraint may be applied that PCell_new and PCell_old should have the same SCS and / or duplex mode (e.g., FDD or TDD). Alternatively, through the SS set index association between PCell_new and PCell_old, the PCell function for PDCCH monitoring may be performed in PCell_new. For example, if PCell_new and PCell_old have a predefined or preconfigured association relationship, the terminal may perform PDCCH monitoring in PCell_new by replacing the settings of the SS set index n of PCell_old with at least some settings of the SS set index m of PCell_new. The association relationship between the SS set index n of PCell_old and the SS set index m of PCell_new may be pre-configured, or automatically set when n=m.

[0355] [Implementation #2-2] Functions related to random access procedure

[0356] At least some functions related to the random access procedure may be performed in PCell_new. For example, HARQ-ACK transmission corresponding to msg1 / 2 / 3 / 4 and msg4 of the 4-step RACH procedure and at least part of HARQ-ACK transmission corresponding to msgA / B and msgb of the 2-step RACH procedure may be performed in PCell_new.

[0357] According to alternative implementation #2-2-1, when PRACH (or msgA) transmission is performed in PCell_new, the setting of the corresponding PRACH (or msgA) transmission resources may be set according to each serving cell. According to alternative implementation #2-2-2, when PRACH (or msgA) transmission is performed in PCell_new, the setting of the corresponding pre-configured PRACH (or msgA) transmission resources in PCell_old may be inherited to PCell_new.

[0358] [Implementation #2-3] PUCCH transmission function

[0359] At least some of the PUCCH transmissions may be performed in PCell_new. That is, at least some of the PUCCH transmissions that are periodically and / or semi-statically indicated for SR and / or CSI transmissions, and / or at least some of the PUCCH transmissions that are non-periodically indicated for HARQ-ACK transmissions may be performed in PCell_new. According to alternative implementation #2-3-1, when PUCCH transmissions are performed in PCell_new, the settings of the corresponding PUCCH transmission resources may be set according to each serving cell. According to alternative implementation #2-3-2, when PUCCH transmissions are performed in PCell_new, the settings of the corresponding pre-configured PUCCH transmission resources in PCell_old may be inherited to PCell_new.

[0360] Among the functions (or operations) executed in PCell_old, at least some of the functions to be executed in PCell_new may be configured by high-layer signaling. According to an embodiment, among the functions executed in PCell_old, some (K) candidate functions may be configured by high-layer signaling, and at least one operation to be actually executed in PCell_new among the K operations may be dynamically indicated in the same manner as proposed in embodiment #1.

[0361] According to an embodiment, the terminal may execute some functions of PCell_old in PCell_new only within a certain time (e.g., T1 time slot or T2 milliseconds) after changing PCell from PCell_old to PCell_new according to a PCell change indication, and execute all functions of PCell_old in PCell_new after the certain time has passed.

[0362] [Implementation #3] Example of PCell Change When SCell to be Operated as PCell_new is Deactivated or Sleeps

[0363] Fig.23 An example of a process of changing a PCell based on a state of a target cell in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig.23 A method of operating a terminal is illustrated.

[0364] Reference Fig.23In step S2301, the terminal identifies the state of the target cell for PCell change. That is, the terminal can determine the target cell to be operated as PCell_new among multiple SCells configured for carrier aggregation, and identify the state of the determined target cell. The target cell to be operated as PCell_new may be an SCell indicated by DCE or MAC CE to be operated as PCell, as described in implementation #1. Here, the state of the target cell may include a state showing whether the target cell is activated and / or whether the target cell is dormant. For example, if the target cell is a cell operating in an inactive BWP or a dormant BWP, the terminal may determine that the state of the target cell is a deactivated state.

[0365] In step S2303, the terminal determines whether the target cell can be changed to PCell. If the state of the target cell is deactivated or the active BWP in the target cell is dormant, the terminal determines that the PCell cannot be changed to the target cell. On the other hand, if the state of the target cell is activated and the active BWP is not dormant, the terminal determines that the PCell can be changed to the target cell.

[0366] When the PCell cannot be changed to the target cell, in step S2305, the terminal performs additional operations for the PCell change. For example, the terminal may perform an operation for changing the state of the target cell or selecting a new target cell. To this end, the terminal may send and / or receive at least one message or signal to the base station. According to an embodiment, the terminal may perform a BWP switch to a BWP that is not in a dormant state among the BWPs configured in the target cell. A BWP that is not in a deactivated state or a dormant state may be preconfigured. According to another embodiment, the terminal may select another SCell that is not in a deactivated state as the target cell. For example, in an SCell included in the same CG or PUCCH group as the PCell, the terminal may select an SCell with a specified service cell index as the new target cell. The specified service cell index may be the lowest service cell index, the highest service cell index, or a preconfigured service cell index.

[0367] In step S2307, the terminal performs a PCell change process. That is, if an additional operation is performed in step S2305, the terminal can change the PCell in the BWP after switching or change the PCell to another SCell. Alternatively, if it is determined in step S2303 that the PCell can be changed to the target cell, the terminal can change the PCell from the existing PCell_old to the target cell. Therefore, the target cell can become the PCell_new of the terminal.

[0368] In reference Fig.23In the description, if the PCell cannot be changed to the target cell, the terminal performs additional operations for the PCell change and then performs the PCell change process. However, according to an embodiment, the terminal may not perform any PCell change process but maintain the existing PCell_old. That is, if the PCell change target cell is in a deactivated state, the terminal may not change the PCell but perform the functions of the PCell in the existing PCell_old.

[0369] Fig.24 An example of a process of preventing a PCell from changing a target cell to be inactive in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig.24 A method of operating a terminal is illustrated.

[0370] Reference Fig.24 In step S2401, the terminal identifies a target cell candidate for PCell change. According to an embodiment, the target cell candidate for PCell change may be indicated by the base station through DCI or MAC CE. According to an embodiment, the target cell candidate for PCell change may be determined during the SCell configuration process.

[0371] In step S2403, the terminal applies the inactivity prevention configuration of the identified target cell candidate. That is, the terminal can restrict the identified target cell candidate from undergoing a transition to an inactive state. For example, in order to restrict the identified target cell candidate from undergoing a transition to an inactive state, the terminal may not operate a timer related to the inactivity of the SCell. The timer related to the inactivity of the SCell can be configured to be inactive through a data scheduling DCI of a DCI format 2_6 or a DCI format 0_1 / 0_2 / 1_1 / 1_2. As another example, in order to prevent the target cell candidate from undergoing a transition to an inactive state, the terminal may ignore the transition indication of the inactive state of the target cell candidate.

[0372] In reference Fig.24 In the description of , the terminal restricts the target cell candidate from undergoing a transition to an inactive state, but the present disclosure is not limited thereto. For example, the terminal may restrict the target cell candidate from undergoing a transition to a dormant state. The transition to the dormant state may be restricted by prohibiting the operation of a dormant-related timer or ignoring a transition indication to the dormant state.

[0373] Fig.25 An example of a procedure for changing a PCell in a wireless communication system according to an embodiment of the present disclosure is illustrated. Fig.25 A method of operating a terminal is illustrated.

[0374] Reference Fig.25In step S2501, the terminal performs communication in the first cell (ie, PCell) and the second cell (ie, SCell). That is, the terminal can perform a random access process with the base station, configure the first cell as PCell in the service cell of the base station, and configure at least one second cell as SCell. Here, the first cell may be a cell in which the random access process is performed, and the at least one second cell may be a cell belonging to the same cell group (ie, primary cell group (MCG)) as the first cell, or a cell belonging to a different cell group (ie, secondary cell group (SCG)). The terminal can perform communication through the first cell (ie, PCell) and the second cell (ie, SCell).

[0375] In step S2503, the terminal receives an indication to change the PCell to the second cell. That is, the terminal may receive information indicating that the PCell will be changed from the first cell to the second cell through DCI or MAC CE. For example, as described in implementation #1, the terminal may receive an indication for the PCell change through DCI indicating PUCCH cell switching, PUCCH command, SPS / CG configuration, or NES state.

[0376] In step S2505, the terminal determines whether the second cell is in an inactive state. That is, the terminal can determine whether the second cell, which is the target cell of the PCell change, is in an inactive state. If the second cell is in an inactive state, the terminal continues to perform the following step S2507. Alternatively, when the BWP used by the SCell in the second cell is a dormant BWP, the terminal can also continue to perform step S2507.

[0377] If the second cell is in an inactive state, in step S2507, the terminal changes the PCell to a third cell or another BWP of the second cell. That is, if the second cell is in an inactive state, the terminal may change the PCell to a third cell that is not in an inactive state. Here, the third cell may be an SCell with the lowest serving cell index, the highest serving cell index, or a specified value index in the SCell in the same CG or PUCCH group as the first cell. Alternatively, if the active BWP of the SCell in the second cell is dormant, the terminal may perform a BWP switch to another BWP that is not in a dormant state and change the PCell to the second cell. Here, the other BWP is a BWP that is not in a dormant state and may be pre-set. Next, the terminal may perform at least some of all the functions of the PCell that is performed or configured to be performed in the first cell in another BWP of the second cell or in the third cell.

[0378] If the second cell is not in an inactive state, in step S2507, the terminal performs a process of changing the PCell to the second cell. That is, the terminal can change the PCell from the first cell to the second cell. Next, the terminal can perform at least some of all functions of the PCell performed or configured to be performed in the first cell in the second cell.

[0379] [Implementation #4] When both the primary DRX group and the secondary DRX group of the terminal are configured, if the frequency range (FR) to which PCell_old belongs is different from the FR to which PCell_new belongs, the DRX group configuration may be changed. For example, if PCell_new belongs to the secondary DRX group before the PCell is changed, the secondary DRX group configuration may not be applied after the PCell group is changed, and the primary DRX group configuration may be applied to each service cell in common. As another example, if PCell_new belongs to the secondary DRX group before the PCell is changed, the primary DRX group configuration parameters may be applied to the service cell corresponding to the FR to which PCell_new belongs, and the secondary DRX group configuration parameters may be applied to the service cell corresponding to the FR to which PCell_old belongs. In this case, there may be an advantage in maintaining the DRX group configuration to which PCell belongs as the primary DRX group configuration before and after the PCell is changed.

[0380] As described above, the present disclosure proposes dynamically changing the PCell of the terminal through PCell change indication signaling, and terminal operations related to PDCCH monitoring, random access process, PUCCH transmission or DRX according to the PCell change, so as to save energy for the base station.

[0381] The example of the above-mentioned proposed method may be included as one of the implementation methods of the present disclosure, and thus may be regarded as a type of the proposed method. In addition, the above-mentioned proposed method may be implemented independently, or some of the proposed methods may be combined (or merged). The rule may be defined so that the base station notifies the UE of information on whether to apply the proposed method (or information about the rule of the proposed method) through a predefined signal (e.g., a physical layer signal or a higher layer signal).

[0382] Those skilled in the art will appreciate that the present disclosure can be implemented in other specific ways than those described herein without departing from the spirit and essential characteristics of the present disclosure. Therefore, the above exemplary embodiments should be interpreted in all respects as illustrative and not restrictive. The scope of the present disclosure should be determined by the appended claims and their legal equivalents, rather than by the above description, and it is intended that all changes that come within the meaning and equivalent range of the appended claims are covered therein. In addition, it will be apparent that some claims that refer to specific claims can be combined with another claim that refers to other claims other than the specific claims to constitute an embodiment, or new claims can be added by amendment after the application is submitted.

[0383] Industrial Applicability

[0384] Embodiments of the present disclosure are applicable to various radio access systems. Examples of various radio access systems include the 3rd Generation Partnership Project (3GPP) or 3GPP2 system.

[0385] The embodiments of the present disclosure are applicable not only to various radio access systems but also to all technical fields to which various radio access systems are applied. In addition, the proposed method is applicable to millimeter wave and terahertz wave communication systems using ultra-high frequency bands.

[0386] Additionally, embodiments of the present disclosure are applicable to a variety of applications, such as autonomous vehicles, drones, and the like.

Claims

1. A method for operating a terminal in a wireless communication system, the method comprising: Performing a random access procedure with a base station; Configure a first cell among the multiple cells of the base station as a primary cell PCell; Configure a second cell among the multiple cells of the base station as a secondary cell (SCell); receiving an instruction to change the PCell to the second cell; as well as Based on the second cell being in an inactive state or the active bandwidth part BWP of the terminal in the second cell being dormant, the PCell is changed to a third cell different from the second cell, or the PCell is changed to the second cell after switching the active BWP.

2. The method according to claim 1, wherein: The indication to change the PCell to the second cell is received based on at least one of the following items: downlink control information DCI indicating physical uplink control channel PUCCH cell switching, physical downlink control channel PDCCH command, SPS / configuration scheduling CG configuration of a specific index, or network energy saving NES state.

3. The method according to claim 1, further comprising: At least some of the functions of the PCell are transferred from the first cell to the second cell.

4. The method according to claim 3, wherein: The at least some functions include at least one of the following items: a function of monitoring the PDCCH in a common search space CSS set, a function related to a random access procedure, or a PUCCH transmission function.

5. The method according to claim 3, wherein: The at least some functions are indicated based on at least one of higher layer signaling or DCI.

6. The method according to claim 1, wherein: The primary DRX group configuration is applied to at least one of: another BWP of the second cell to which the PCell is changed or the third cell.

7. The method according to claim 6, wherein: After the PCell is changed, the secondary DRX group configuration is applied to the first cell.

8. The method according to claim 1, further comprising: identifying at least one target cell candidate that can be changed to the PCell; as well as Transition of the at least one target cell candidate to an inactive state is restricted.

9. The method according to claim 8, wherein: The limiting the transition to the inactive state is performed based on at least one of: disabling operation of an inactivity-related timer or ignoring an indication of the transition to the inactive state.

10. The method according to claim 1, wherein: The changing of the PCell is performed after a predefined or configured time has passed from a time when the indication to change the PCell to the second cell is received.

11. The method according to claim 1, further comprising: After the PCell is changed to the second cell or the third cell, the PCell is changed to the first cell based on expiration of a timer that starts running due to the change of the PCell.

12. A method for operating a base station in a wireless communication system, the method comprising: Performing a random access procedure with a terminal; Configure a first cell among the multiple cells of the base station as a primary cell PCell of the terminal; Configure a second cell among the multiple cells of the base station as a secondary cell SCell of the terminal; as well as An instruction to change the PCell to the second cell is sent to the terminal.

13. A terminal in a wireless communication system, the terminal comprising: Transceiver; as well as a processor coupled to the transceiver, Wherein, the processor is configured to: Performing a random access procedure with a base station; Configure a first cell among the multiple cells of the base station as a primary cell PCell; Configure a second cell among the multiple cells of the base station as a secondary cell (SCell); receiving an instruction to change the PCell to the second cell; and Based on the second cell being in an inactive state or the active bandwidth part BWP of the terminal in the second cell being dormant, the PCell is changed to a third cell different from the second cell, or the PCell is changed to the second cell after switching the active BWP.

14. A base station in a wireless communication system, the base station comprising: Transceiver; as well as a processor coupled to the transceiver, Wherein, the processor is configured to: Performing a random access procedure with a terminal; Configure a first cell among the multiple cells of the base station as a primary cell PCell of the terminal; configuring a second cell among the multiple cells of the base station as a secondary cell (SCell) of the terminal; and An instruction to change the PCell to the second cell is sent to the terminal.

15. A communication device, comprising: at least one processor; as well as at least one computer memory coupled to the at least one processor and storing instructions that, when executed by the at least one processor, indicate operations, The operations include: Performing a random access procedure with a base station; Configure a first cell among the multiple cells of the base station as a primary cell PCell; Configure a second cell among the multiple cells of the base station as a secondary cell (SCell); receiving an instruction to change the PCell to the second cell; and Based on the second cell being in an inactive state or the active bandwidth part BWP of the terminal in the second cell being dormant, the PCell is changed to a third cell different from the second cell, or the PCell is changed to the second cell after switching the active BWP.

16. A non-transitory computer-readable medium storing at least one instruction, the non-transitory computer-readable medium including the at least one instruction executable by a processor, in, The at least one instruction controls the device to: Performing a random access procedure with a base station; Configure a first cell among the multiple cells of the base station as a primary cell PCell; Configure a second cell among the multiple cells of the base station as a secondary cell (SCell); receiving an instruction to change the PCell to the second cell; as well as Based on the second cell being in an inactive state or the active bandwidth part BWP of the terminal in the second cell being dormant, the PCell is changed to a third cell different from the second cell, or the PCell is changed to the second cell after switching the active BWP.

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