APPARATUS AND METHOD FOR CHANGE PRIMARY CELL IN A WIRELESS COMMUNICATION SYSTEM - Patent application

Abstract

The present disclosure relates to an apparatus and method for changing a primary cell (PCell) in a wireless communication system, and an operation method of a terminal may include the steps of performing a random access procedure with a base station, setting a first cell among the cells of the base station as a PCell, setting a second cell among the cells of the base station as an SCell (secondary cell), receiving an instruction to change the PCell to the second cell, and, if the second cell is in an inactivation state or an active BWP (bandwidth part) of the terminal in the second cell is in a dormant state, 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.

Description

[Technical Field]

[0001] BACKGROUND I. Field The following description relates to wireless communication systems, and more particularly to apparatus and methods for changing a primary cell (PCell) in a wireless communication system. [Background technology]

[0002] Wireless access systems have been widely deployed to provide various types of communication services such as voice and data. Generally, wireless access systems are multiple access systems that can support communication with multiple users by sharing available system resources (e.g., bandwidth and transmission power). 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, as many communication devices require large communication capacities, enhanced mobile broadband (eMBB) communication technology, which is more advanced than existing radio access technology (RAT), has been proposed. In addition, not only massive machine-type communications (mMTC) that connects multiple devices and things to provide a variety of services anytime, anywhere, but also communication systems that take reliability and latency-sensitive services / user equipment (UE) into consideration have been proposed. Various technical configurations have been proposed for this purpose. Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure can provide an apparatus and method for dynamically changing a primary cell (PCell) in a wireless communication system.

[0005] The present disclosure can provide an apparatus and method for indicating a PCell change in a wireless communication system.

[0006] The present disclosure can provide an apparatus and method for signaling PCell change related information in a wireless communication system.

[0007] The present disclosure can provide an apparatus and method for changing a PCell from a first cell to a second cell based on a PCell change instruction in a wireless communication system.

[0008] 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.

[0009] The present disclosure can provide an apparatus and method for performing a PCell change procedure based on the state of a PCell change target cell in a wireless communication system.

[0010] The present disclosure can provide an apparatus and a method for changing a bandwidth part (BWP) of a PCell change target cell in a wireless communication system.

[0011] The present disclosure can provide an apparatus and a method for preventing deactivation of a cell subject to PCell change in a wireless communication system.

[0012] The present disclosure can provide an apparatus and method for modifying a DRX group configuration based on a PCell change in a wireless communication system.

[0013] The technical problems to be solved by the present disclosure are not limited to those described above, and other technical problems not described above can be considered by a person of ordinary skill in the art to which the technical configuration of the present disclosure is applied from the embodiments of the present disclosure described below. [Means for solving the problem]

[0014] As an example of the present disclosure, a method for operating a terminal in a wireless communication system may include the steps of performing a random access procedure with a base station, setting a first cell among the cells of the base station as a PCell (primary cell), setting a second cell among the cells of the base station as an SCell (secondary cell), receiving an instruction to change the PCell to the second cell, and, if the second cell is in an inactivation state, if the second cell is in an inactivation state or if an active BWP (bandwidth part) of the terminal in the second cell is 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.

[0015] As an example of the present disclosure, a method of operating a base station in a wireless communication system may include the steps of performing a random access procedure with a terminal, setting a first cell among the cells of the base station as a PCell (primary cell) of the terminal, setting a second cell among the cells of the base station as a SCell (secondary cell) of the terminal, and transmitting an instruction to the terminal not to change the PCell to the second cell.

[0016] As an example of the present disclosure, a terminal in a wireless communication system includes a transceiver and a processor connected to the transceiver, and the processor performs a random access procedure with a base station, sets a first cell among the cells of the base station as a PCell (primary cell), sets a second cell among the cells of the base station as an SCell (secondary cell), receives an instruction to change the PCell to the second cell, and, if the second cell is in an inactive state, if the second cell is in an inactive state or if an active BWP (bandwidth part) of the terminal in the second cell is dormant, controls to change the PCell to a third cell different from the second cell, or to change the PCell to the second cell after switching the active BWP.

[0017] As an example of the present disclosure, a base station in a wireless communication system includes a transceiver and a processor connected to the transceiver, and the processor can perform a random access procedure with a terminal, set a first cell among the cells of the base station as a PCell (primary cell) of the terminal, set a second cell among the cells of the base station as a SCell (secondary cell) of the terminal, and transmit an instruction to the terminal to change the PCell to the second cell.

[0018] As an example of the present disclosure, a communication device includes at least one processor and at least one computer memory connected to the at least one processor and storing instructions that instruct operations when executed by the at least one processor, wherein the operations include performing a random access procedure with a base station, setting a first cell among the cells of the base station as a PCell (primary cell), setting a second cell among the cells of the base station as an Scell ​​(secondary cell), receiving an instruction to change the PCell to the second cell, and, if the second cell is in an inactivation state or an active BWP (bandwidth part) 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.

[0019] As an example of the present disclosure, a non-transitory computer-readable medium storing at least one instruction includes the at least one instruction executable by a processor, and the at least one instruction can control the device to perform a random access procedure with a base station, set a first cell among the base station's cells as a PCell (primary cell), set a second cell among the base station's cells as an SCell (secondary cell), receive an instruction to change the PCell to the second cell, and if the second cell is in an inactivation state or an active BWP (bandwidth part) of the terminal in the second cell is 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.

[0020] The above-described aspects of the present disclosure are merely some of the preferred embodiments of the present disclosure, and various embodiments reflecting the technical features of the present disclosure can be derived and understood by those having ordinary skill in the art based on the detailed description of the present disclosure set forth below. [Effects of the Invention]

[0021] The embodiments according to the present disclosure may have the following advantages.

[0022] According to the present disclosure, the energy consumption of the base station can be reduced.

[0023] The effects obtained by the embodiments of the present disclosure are not limited to the effects described above, and other effects not described above can be clearly derived and understood by a person skilled in the art to which the technical configuration of the present disclosure is applied from the following description of the embodiments of the present disclosure. In other words, unintended effects resulting from implementing the configurations described in the present disclosure can also be derived by a person skilled in the art from the embodiments of the present disclosure. [Brief explanation of the drawings]

[0024] [Figure 1] 1 illustrates the structure of a wireless communication system to which the present disclosure can be applied. [Figure 2] 1 illustrates an example of a wireless device to which the present disclosure can be applied. [Figure 3] 1 illustrates a frame structure in a wireless communication system to which the present disclosure can be applied. [Figure 4] 1 illustrates an example of a resource grid in a wireless communication system to which the present disclosure can be applied. [Figure 5] 1 illustrates an example of a physical resource block in a wireless communication system to which the present disclosure can be applied. [Figure 6] 1 illustrates an example of a slot structure in a wireless communication system to which the present disclosure can be applied. [Figure 7]1 illustrates examples of physical channels used in a wireless communication system to which the present disclosure can be applied, and a general signal transmission / reception method using these channels. [Figure 8] 1 illustrates an example of mapping physical channels within a slot in a wireless communication system to which the present disclosure can be applied. [Figure 9] 1 shows the structure of a synchronization signal and broadcast channel block (SSB) applicable to the present disclosure. [Figure 10] 1 shows SSB transmission applicable to the present disclosure. [Figure 11] 1 shows examples of SSB candidate locations applicable to the present disclosure. [Figure 12] 10 illustrates an example of downlink time synchronization information applicable to the present disclosure. [Figure 13] 1 illustrates an example of a system information acquisition procedure applicable to the present disclosure. [Figure 14] 1 shows an example of multi-beam transmission applicable to the present disclosure. [Figure 15] 10 shows an example of indicating the actual transmitted SSBs applicable to the present disclosure. [Figure 16] 1 illustrates an example of a collision-based random access procedure applicable to the present disclosure. [Figure 17] 1 illustrates an example of a non-collision based random access procedure applicable to the present disclosure. [Figure 18] 1 illustrates an example of a network initial connection and communication procedure applicable to the present disclosure. [Figure 19] 1 shows an example of a DRX cycle applicable to the present disclosure. [Figure 20] 10 illustrates an example of a PCell change instruction procedure in a wireless communication system according to an embodiment of the present disclosure. [Figure 21] 10 illustrates an example of a procedure for changing a PCell in a wireless communication system according to an embodiment of the present disclosure. [Figure 22] 10 illustrates an example of a procedure for transferring at least a portion of the functionality of a PCell in a wireless communication system according to one embodiment of the present disclosure. [Figure 23]10 illustrates an example of a procedure for changing a PCell based on the state of a target cell in a wireless communication system according to an embodiment of the present disclosure. [Figure 24] 10 illustrates an example of a procedure for preventing deactivation of a cell that is a target for PCell change in a wireless communication system according to an embodiment of the present disclosure. [Figure 25] 10 illustrates an example of a procedure for changing a PCell in a wireless communication system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following examples combine the components and features of the present disclosure in a predetermined form. Each component or feature can be considered optional unless otherwise explicitly stated. Each component or feature can be implemented in a form not combined with other components or features. Also, some components and / or features can be combined to form an embodiment of the present disclosure. The order of operations described in the embodiments of the present disclosure can be changed. Some components or features of any embodiment may be included in other embodiments or may be replaced with corresponding components or features of other embodiments.

[0026] In describing the drawings, procedures or steps that may obscure the gist of the present disclosure are not described, and procedures or steps that can be understood by a person skilled in the art are not described.

[0027] Throughout the specification, when a part "comprising" or "including" a certain element(s), this does not mean that the part or part "comprising" or "including" a certain element(s) does not exclude other elements, but may further include other elements, unless otherwise specified to the contrary. Furthermore, terms such as "unit," "unit," and "module" used in the specification refer to a unit that processes at least one function or operation, which can be realized by hardware, software, or a combination of hardware and software. Furthermore, in the context of describing this disclosure (particularly in the context of the claims below), the words "a" or "an," "one," "the," and similar related words can be used to include both the singular and the plural, unless otherwise indicated in the specification or clearly contradicted by the context.

[0028] In this specification, the embodiments of the present disclosure have been described with a focus on the data transmission / reception relationship between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. Certain operations described herein as being performed by a base station may also be performed by an upper node of the base station in some cases.

[0029] That is, in a network consisting of multiple network nodes including a base station, various operations performed for communication with a mobile station may be performed by the base station or other network nodes other than the base station. In this case, the term "base station" may be replaced with terms such as fixed station, Node B, eNB (eNode B), gNB (gNode B), ng-eNB, advanced base station (ABS), or access point.

[0030] Furthermore, in the embodiments of the present disclosure, the term "terminal" may be replaced with terms such as user equipment (UE), mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, or advanced mobile station (AMS).

[0031] Also, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in the case of an uplink, a mobile station can be the transmitting end and a base station can be the receiving end. Similarly, in the case of a downlink, a mobile station can be the receiving end and a base station can be the transmitting end.

[0032] Embodiments of the present disclosure may be supported by standard documents disclosed in at least one of wireless access systems, such as an IEEE 802.xx system, a 3GPP (registered trademark) (3rd Generation Partnership Project) system, a 3GPP LTE (Long Term Evolution) system, a 3GPP 5G (5th generation) NR (New Radio) system, and a 3GPP2 system. In particular, embodiments of the present disclosure may be supported by 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321, and 3GPP TS 38.331 documents.

[0033] Furthermore, the embodiments of the present disclosure may be applied to other wireless access systems and are not limited to the above-mentioned systems, for example, to systems that are later adopted after the 3GPP 5G NR system, and are not limited to a specific system.

[0034] That is, any obvious steps or parts not described in the embodiments of the present disclosure can be explained by referring to the above documents, and all terms disclosed in this specification can be explained by the above standard documents.

[0035] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to explain exemplary embodiments of the present disclosure, and is not intended to show the only embodiments in which the technical configuration of the present disclosure can be implemented.

[0036] Furthermore, specific terms used in the embodiments of the present disclosure are provided to aid in understanding the present disclosure, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present disclosure.

[0037] The following techniques can be applied to various wireless 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), and single carrier frequency division multiple access (SC-FDMA).

[0038] For clarity of the following description, the description will be based on a 3GPP communication system (e.g., LTE, NR, etc.), but the technical idea of ​​the present disclosure is not limited thereto. LTE may refer to technology from 3GPP TS 36.xxx Release 8 or later. Specifically, LTE technology from 3GPP TS 36.xxx Release 10 or later may be referred to as LTE-A, and LTE technology from 3GPP TS 36.xxx Release 13 or later may be referred to as LTE-A pro. 3GPP NR may refer to technology from TS 38.xxx Release 15 or later. 3GPP 6G may refer to technology from TS Release 17 and / or Release 18 or later. "xxx" refers to the specific number of the standard document. LTE / NR / 6G may be referred to as 3GPP systems.

[0039] 3GPP 6G may refer to technology after 3GPP NR based on the 3GPP system. 3GPP 6G is not limited to a release or a specific TS document, and the name may be in a form different from 3GPP 6G. That is, 3GPP 6G may refer to technology introduced after 3GPP NR and is not limited to a specific form.

[0040] The following description will focus on the 3GPP NR system, but is not limited thereto and can also be applied to 3GPP 6G. Furthermore, the following description may be partially modified in consideration of the 3GPP 6G system and is not limited to a specific form. However, for the sake of convenience, the following description will focus on the 3GPP NR system. For background techniques, terms, abbreviations, etc. used in this disclosure, reference may be made to the matters described in standard documents published prior to this disclosure. For example, reference may be made to the 36.xxx and 38.xxx standard documents.

[0041] System in general

[0042] As more communication devices require greater communication capacity, there is a growing need for improved mobile broadband communication compared to existing radio access technologies (RATs). Massive Machine Type Communications (MTC), which connects a large number of devices and objects to provide a variety of services anytime, anywhere, is also one of the major issues being considered for next-generation communications. Furthermore, communication system designs that take into account reliability- and latency-sensitive services / terminals are being discussed. Thus, the introduction of next-generation RATs that take into account enhanced mobile broadband communication (eMBB), massive MTC (mMTC), and Ultra-Reliable and Low Latency Communication (URLLC), etc., is being discussed. For convenience, these technologies are referred to as NR in this disclosure. NR is an example of a 5G RAT.

[0043] New RAT systems, including NR, use an OFDM transmission scheme or a similar transmission scheme. A new RAT system may follow OFDM parameters different from those of LTE. Alternatively, a new RAT system may follow the existing LTE / LTE-A numerology but support a larger system bandwidth (e.g., 100 MHz). Alternatively, one cell may support multiple numerologies. That is, terminals operating with different numerologies can coexist within one cell.

[0044] A numerology corresponds to one subcarrier spacing in the frequency domain. Different numerologies can be defined by scaling the reference subcarrier spacing by an integer N.

[0045] Additionally, new RAT systems, including 6G, can be considered as next-generation RATs. New RAT systems, including 6G, can consider, but are not limited to, i) extremely high data rates per device, ii) a very large number of connected devices, iii) global connectivity, iv) very low latency, v) low energy consumption for battery-free IoT devices, vi) ultra-reliable connections, and vii) connected intelligence with machine learning capabilities. Taking into account the above-mentioned aspects, new RAT systems, including 6G, can consider using the terahertz (THz) frequency band at a higher frequency than NR systems for wider bandwidth and higher transmission speeds. New RAT systems, including 6G, can overcome existing limitations by applying AI / ML (artificial intelligence / machine learning), but are not limited to this.

[0046] FIG. 1 is a diagram illustrating the structure of a wireless communication system to which the present disclosure can be applied. Referring to FIG. 1, the NG-RAN is composed of a gNB that provides an NG-Radio Access (NG-RA) user plane (i.e., a new access stratum (AS) sub-layer / Packet Data Convergence Protocol (PDCP) / Radio Link Control (RLC) / MAC / PHY) and a control plane (RRC) protocol termination for a UE. The gNBs are interconnected via an Xn interface. The gNBs are also connected to a New Generation Core (NGC) via an NG interface. More specifically, the gNBs are connected to an Access and Mobility Management Function (AMF) via an N2 interface and to a User Plane Function (UPF) via an N3 interface. FIG. 1 is a structure based on an NR system. In a 6G system, the structure of FIG. 1 may be used identically or with some modifications, and is not limited to a specific form.

[0047] FIG. 2 is a diagram illustrating an example of a wireless device to which the present disclosure can be applied.

[0048] 2, a wireless device 200 may transmit and receive wireless signals via various wireless access technologies (e.g., LTE, LTE-A, LTE-A pro, 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.

[0049] The processor 202 may be configured to control the memory 204 and / or the transceiver 206 to implement the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. For example, the processor 202 may process information in the memory 204 to generate first information / signals, and then transmit a wireless signal containing the first information / signals via the transceiver 206. The processor 202 may also receive a wireless signal containing second information / signals via the transceiver 206, and then store information obtained from signal processing of the second information / signals in the memory 204. The memory 204 may be connected to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software code including instructions for performing some or all of the processes controlled by the processor 202 or for implementing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. Here, the processor 202 and the memory 204 may be part of a communications modem / circuit / chip designed to implement wireless communication technology. The transceiver 206 may be connected to the processor 202 and may transmit and / or receive wireless signals via at least one antenna 208. The transceiver 206 may include a transmitter and / or a receiver. The transceiver 206 may be mixed with an RF (radio frequency) unit. In this disclosure, a wireless device may also refer to a communication modem / circuit / chip.

[0050] The hardware elements of the wireless device 200 are described in more detail below. Without limitation, at least one protocol layer may be implemented by the at least one processor 202. For example, the at least one processor 202 may implement at least one layer (e.g., functional layers such as physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), radio resource control (RRC), and service data adaptation protocol (SDAP)). The at least one processor 202 may generate at least one protocol data unit (PDU) and / or at least one service data unit (SDU) in accordance with the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The at least one processor 202 may generate messages, control information, data, or information in accordance with the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein. The at least one processor 202 can generate and provide signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information to the at least one transceiver 206 according to the functions, procedures, suggestions, and / or methods disclosed herein. The at least one processor 202 can receive signals (e.g., baseband signals) from the at least one transceiver 206 and obtain the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein.

[0051] The at least one processor 202 may also be referred to as a controller, microcontroller, microprocessor, or microcomputer. The at least one processor 202 may be implemented using hardware, firmware, software, or a combination thereof. For example, the at least one processor 202 may include 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). The descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein may be included in the at least one processor 202 or may be stored in at least one memory 204 and executed by the at least one processor 202. The descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein may be implemented using firmware or software in the form of code, instructions and / or collections of instructions.

[0052] At least one memory 204 may be coupled to the at least one processor 202 and may store various types of data, signals, messages, information, programs, code, instructions, and / or instructions. The at least one memory 204 may be comprised of read only memory (ROM), random access memory (RAM), erasable programmable read only memory (EPROM), flash memory, a hard drive, registers, cache memory, computer-readable storage media, and / or combinations thereof. The at least one memory 204 may be located internal and / or external to the at least one processor 202. Additionally, the at least one memory 204 may be coupled to the at least one processor 202 via various technologies, such as wired or wireless connections.

[0053] The at least one transceiver 206 can transmit user data, control information, wireless signals / channels, etc., as described in the methods and / or operational flowcharts herein, etc., to at least one other device. The at least one transceiver 206 can receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, suggestions, methods and / or operational flowcharts disclosed herein, etc., from at least one other device. For example, the at least one transceiver 206 can be coupled to at least one processor 202 and can transmit and receive wireless signals. For example, the at least one processor 202 can control the at least one transceiver 206 to transmit user data, control information, or wireless signals to at least one other device. The at least one processor 202 can also control the at least one transceiver 206 to receive user data, control information, or wireless signals from at least one other device. Furthermore, the at least one transceiver 206 may be connected to at least one antenna 208, and the at least one transceiver 206 may be configured to transmit and receive user data, control information, radio signals / channels, etc., as described in the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed herein, via the at least one antenna 208. In this specification, the at least one antenna may refer to multiple physical antennas or multiple logical antennas (e.g., antenna ports). The at least one transceiver 206 may convert the received user data, control information, radio signals / channels, etc., from RF band signals to baseband signals for processing using the at least one processor 202. The at least one transceiver 206 may convert the user data, control information, radio signals / channels, etc., processed using the at least one processor 202, from baseband signals to RF band signals. For this purpose, the at least one transceiver 206 may include an (analog) oscillator and / or a filter.

[0054] The components of the wireless device described with reference to Figure 2 may be referred to by other terms from a functional standpoint. For example, the processor 202 may be referred to as a control unit, the transceiver 206 as a communication unit, and the memory 204 as a storage unit. In some cases, the communication unit may be used to include at least a part of the processor 202 and the transceiver 206.

[0055] The structure of the wireless device described with reference to Fig. 2 can be understood as the structure of at least a portion of various devices. For example, it may be at least a portion of various devices (e.g., a robot, a vehicle, an XR device, a mobile device, a home appliance device, an IoT device, an AI device / server, etc.). Furthermore, in various embodiments, the device may further include other components in addition to the components illustrated in Fig. 2.

[0056] For example, the device may be a portable device such as a smartphone, a smart pad, a wearable device (e.g., a smart watch, smart glasses), a portable computer (e.g., a laptop, etc.), 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 connection to another device (e.g., an audio input / output port, a video input / output port), and an input / output unit for inputting and outputting image information / signals, audio information / signals, data, and / or information input by a user.

[0057] For example, the device may be a mobile device such as a mobile robot, a vehicle, a train, an airborne / unmanned vehicle (AV), a ship, etc. In this case, the device may further include at least one of a driving unit including at least one of an engine, a motor, a powertrain, wheels, a brake, and a steering unit of the device, a power supply unit that supplies power and includes a wired / wireless charging circuit, a battery, etc., a sensor unit that detects status information, environmental information, and user information of the device or its surroundings, an autonomous driving unit that performs functions such as route maintenance, speed adjustment, and destination setting, and a position measurement unit that obtains position information of the mobile device through a global positioning system (GPS) and various sensors.

[0058] For example, the device may be an XR device such as an HMD, a head-up display (HUD) installed in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, 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 and a battery, an input / output unit that acquires control information, data, etc. from the outside and outputs the generated XR object, and a sensor unit that detects status information, environmental information, and user information of the device or its surroundings.

[0059] For example, the device may be a robot that can be classified into industrial, medical, domestic, military, etc. depending on the purpose or field of use. In this case, the device may further include at least one of a sensor unit that detects status information, environmental information, and user information of the device or its surroundings, and a driving unit that performs various physical operations such as moving robot joints.

[0060] For example, the device may be an AI device such as a television, projector, smartphone, PC, laptop, digital broadcasting terminal, tablet PC, wearable device, set-top box (STB), radio, washing machine, refrigerator, digital signage, robot, or vehicle. In this case, the device may further include at least one of an input unit that acquires various types of data from the outside, an output unit that generates output related to vision, hearing, or touch, a sensor unit that detects status information, environmental information, or user information about the device or its surroundings, and a training unit that trains a model configured with an artificial neural network using learning data. The structure of the wireless device illustrated in FIG. 2 can be understood as part of a RAN node (e.g., a base station, DU, RU, RRH, etc.). That is, the device illustrated in FIG. 2 may be a RAN node. In this case, the device may further include a wired transceiver for fronthaul and / or backhaul communication. However, if the fronthaul and / or backhaul communication is based on wireless communication, at least one transceiver 206 illustrated in FIG. 2 may be used for the fronthaul and / or backhaul communication, and no wired transceiver may be included.

[0061] FIG. 3 is a diagram illustrating a frame structure in a wireless communication system to which the present disclosure can be applied.

[0062] An NR system can support multiple numerologies. Here, a numerology can be defined by subcarrier spacing and cyclic prefix (CP) overhead. In this case, multiple subcarrier spacings can be derived by scaling the base (reference) subcarrier spacing by an integer N (or μ). Furthermore, even if it is assumed that very low subcarrier spacings are not used at very high carrier frequencies, the numerology used can be selected independently of the frequency band. Furthermore, an NR system can support various frame structures with multiple numerologies.

[0063] The following describes OFDM numerologies and frame structures that can be considered in an NR system. A number of OFDM numerologies supported in an NR system can be defined as shown in Table 1 below.

[0064] [Table 1]

[0065] NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands, a 30 kHz / 60 kHz SCS supports dense urban areas, lower latency, and wider carrier bandwidths, and an SCS of 60 kHz or higher supports bandwidths wider than 24.25 GHz to overcome phase noise. NR frequency bands are defined by two types of frequency ranges (FR1 and FR2). FR1 and FR2 can be configured as shown in Table 2 below. FR2 can also refer to millimeter wave (mmW).

[0066] [Table 2]

[0067] JPEG2025534341000004.jpg129162

[0068] JPEG2025534341000005.jpg31161

[0069] [Table 3]

[0070] [Table 4]

[0071] FIG. 3 shows an example when μ=2 (SCS is 60 kHz). Referring to Table 3, one subframe can include four slots. The one subframe = {1, 2, 4} slots shown in FIG. 3 is an example, and the number of slots that can be included in one subframe is defined as shown in Table 3 or Table 4. In addition, a mini-slot may include 2, 4, or 7 symbols, or may include more or fewer symbols. Possible physical resources in an NR system include an antenna port, a resource grid, a resource element, a resource block, and a carrier part. The physical resources that can be considered in an NR system will now be described in detail.

[0072] First, with regard to antenna ports, an antenna port is defined such that the channel on which a symbol on the antenna port is carried can be inferred from the channel on which another symbol on the same antenna port is carried. If the large-scale properties of the channel on which a symbol on one antenna port is carried can be inferred from the channel on which a symbol on the other antenna port is carried, the two antenna ports are said to have a QC / QCL (quasi co-located or quasi co-location) relationship. Here, the large-scale properties include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0073] In the 6G system, communication can be performed at the above-mentioned terahertz frequency, which is higher than millimeter wave (mmW), and the frame structure can be the same as that shown in FIG. 3 or a separate frame structure for the 6G system, and is not limited to a specific form.

[0074] FIG. 4 illustrates a resource grid in a wireless communication system to which the present disclosure can be applied.

[0075] JPEG2025534341000008.jpg138160

[0076] Point A serves as a common reference point of the resource block grid and is obtained as follows:

[0077] -OffsetToPointA for the primary cell (PCell) downlink indicates the frequency offset between point A and the lowest subcarrier of the lowest resource block that overlaps with the SSB block used by the terminal for initial cell selection. It is expressed in resource block units assuming a subcarrier spacing of 15 kHz for FR1 and a subcarrier spacing of 60 kHz for FR2.

[0078] -absoluteFrequencyPointA indicates the frequency location of point A expressed as ARFCN (absolute radio-frequency channel number).

[0079] Common resource blocks are numbered from 0 upward in the frequency domain for subcarrier spacing setting μ. The center of subcarrier 0 of common resource block 0 for subcarrier spacing setting μ coincides with "point A". Common resource block number in the frequency domain The relationship between JPEG2025534341000009.jpg9154 and the resource elements (k, l) for the subcarrier spacing setting μ is given by the following Equation 1.

[0080] [Formula 1]

number

[0081] JPEG2025534341000011.jpg38161

[0082] [Formula 2]

number

[0083] JPEG2025534341000013.jpg12143 is the common resource block where the BWP starts relative to common resource block 0.

[0084] Fig. 5 illustrates a physical resource block in a wireless communication system to which the present disclosure can be applied, and Fig. 6 illustrates a slot structure in a wireless communication system to which the present disclosure can be applied.

[0085] 5 and 6, a slot includes multiple symbols in the time domain. For example, in the case of the normal CP, one slot includes seven symbols, while in the case of the extended CP, one slot includes six symbols.

[0086] A carrier includes multiple subcarriers in the frequency domain. A resource block (RB) is defined by multiple (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) is defined by multiple consecutive (physical) resource blocks in the frequency domain and can correspond to one numerology (e.g., SCS, CP length, etc.). A carrier can include up to N (e.g., 5) BWPs. Data communication is performed via activated BWPs, and only one BWP can be activated for one terminal. In the resource grid, each element is called a resource element (RE), and one complex symbol can be mapped to it.

[0087] The NR system can support up to 400 MHz per component carrier (CC). If a terminal operating on such a wideband CC keeps the radio frequency (RF) chip for the entire CC on at all times, the terminal's battery consumption may increase. Considering various use cases (e.g., eMBB, URLLC, MMTc, V2X, etc.) operating within a single wideband CC, different numerologies (e.g., subcarrier spacing, etc.) may be supported for each frequency band within the CC. Alternatively, different terminals may have different capabilities for maximum bandwidth. In consideration of this, a base station may instruct a terminal to operate only with a portion of the bandwidth of a wideband CC, rather than the entire bandwidth. For convenience, this portion of the bandwidth is defined as a bandwidth part (BWP). A BWP can consist of consecutive RBs on the frequency axis and correspond to one numerology (e.g., subcarrier spacing, CP length, slot / minislot duration).

[0088] Meanwhile, the base station can configure multiple BWPs even within one CC configured for a terminal. For example, a BWP occupying a relatively small frequency region can be configured in a PDCCH monitoring slot, and the PDSCH indicated in the PDCCH can be scheduled on a larger BWP. Alternatively, if UEs are concentrated in a specific BWP, some terminals can be configured in other BWPs for load balancing. Alternatively, taking into account frequency domain inter-cell interference cancellation between neighboring cells, a central portion of the spectrum in the entire bandwidth can be excluded and both-side BWPs can be configured within the same slot. That is, the base station can configure at least one DL / UL BWP for a terminal associated with a wideband CC. The base station can activate at least one DL / UL BWP among the DL / UL BWPs configured at a particular time (by L1 signaling, MAC control element (CE), RRC signaling, etc.). In addition, the base station can instruct switching to another configured DL / UL BWP (by L1 signaling, MAC CE, RRC signaling, etc.). Alternatively, switching to the configured DL / UL BWP can be performed on a timer basis when a timer value expires. In this case, the activated DL / UL BWP is defined as an active DL / UL BWP. However, in situations such as when the UE is performing an initial access procedure or before an RRC connection is set up, the UE may not be able to receive the configuration for the DL / UL BWP. Therefore, the DL / UL BWP assumed by the UE in such a situation is defined as the initially active DL / UL BWP.

[0089] FIG. 7 illustrates physical channels used in a wireless communication system to which the present disclosure can be applied, and a general signal transmission / reception method using these channels.

[0090] In a wireless communication system, a terminal receives information from a base station via a downlink and transmits information to the base station via an uplink. Information exchanged between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type / use of the information exchanged.

[0091] When a terminal is powered on or newly enters a cell, it performs an initial cell search, such as synchronizing with a base station (S701). To this end, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and acquire information such as a cell identifier (ID). Thereafter, the terminal receives a physical broadcast channel (PBCH) from the base station to acquire broadcast information within the cell. Meanwhile, the terminal receives a downlink reference signal (DL RS) during the initial cell search phase to check the downlink channel status.

[0092] After completing the initial cell search, the terminal can acquire more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) based on the information carried on the PDCCH (S702).

[0093] On the other hand, when the terminal first connects to the base station or when there are no radio resources for signal transmission, the terminal can perform a random access procedure (RACH) with the base station (steps S703 to S706). To this end, the terminal can transmit a specific sequence to a preamble via a physical random access channel (PRACH) (S703 and S705) and receive a response message to the preamble via a PDCCH and a corresponding PDSCH (S704 and S706). In the case of a contention-based RACH, a contention resolution procedure can also be performed.

[0094] After performing the above-described procedures, the UE can then perform a general uplink / downlink signal transmission procedure, such as PDCCH / PDSCH reception (S707) and Physical Uplink Shared Channel (PUSCH) / Physical Uplink Control Channel (PUCCH) transmission (S708). In particular, the UE receives downlink control information (DCI) via the PDCCH. Here, the DCI includes control information such as resource allocation information for the UE, and its format varies depending on its purpose.

[0095] Meanwhile, control information that a terminal transmits to a base station via an uplink or receives from a base station includes downlink / uplink ACK / NACK (Acknowledgement / Non-Acknowledgement) signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indicator), etc. In the case of a 3GPP LTE system, a terminal can transmit the above-mentioned control information such as CQI / PMI / RI via a PUSCH and / or a PUCCH.

[0096] FIG. 8 shows an example of mapping physical channels within a slot in a wireless communication system to which the present disclosure can be applied.

[0097] Referring to Figure 8,

[0098] A DL control channel, DL or UL data, and UL control channel can all be included in one slot. For example, the first N symbols in a slot can be used to transmit the DL control channel (hereinafter referred to as the "DL control region"), and the last M symbols in the slot can be used to transmit the UL control channel (hereinafter referred to as the "UL control region"). N and M are integers equal to or greater than 0. A resource region between the DL control region and the UL control region (hereinafter referred to as the "data region") can be used for DL ​​data transmission or UL data transmission. A time gap for DL-to-UL or UL-to-DL switching can be present between the control region and the data region. The PDCCH can be transmitted in the DL control region, and the PDSCH can be transmitted in the DL data region. Some symbols at the time of transition from DL to UL within a slot can be used as the time gap.

[0099] Downlink (DL) Physical Channels / Signals

[0100] (1) PDSCH

[0101] The PDSCH carries downlink data (e.g., DL-shared channel transport block (DL-SCH TB)). The TB is encoded with a codeword (CW) and then scrambled and modulated before transmission. The CW includes one or more code blocks (CB). One or more CBs can be grouped into a CBG (CB group). Depending on the cell configuration, the PDSCH can carry up to two CWs. Scrambling and modulation are performed for each CW, and modulation symbols generated from each CW are mapped to one or more layers. Each layer is precoded, mapped to resources with DMRS, and transmitted via the corresponding antenna port. The PDSCH can be dynamically scheduled by the PDCCH (configured scheduling) or semi-statically scheduled based on higher layer (e.g., RRC) signaling (and / or Layer 1 (L1) signaling (e.g., PDCCH)). Therefore, in dynamic scheduling, PDSCH transmission is accompanied by PDCCH, but in CS, PDSCH transmission is not accompanied by PDCCH. CS includes SPS (semi-persistent scheduling).

[0102] (2) PDCCH

[0103] The PDCCH carries Downlink Control Information (DCI). For example, the PCCCH (i.e., DCI) carries the transmission format and resource allocation of the DL-SCH, frequency / time resource allocation information for the UL-SCH (shared channel), paging information for the PCH (paging channel), system information on the DL-SCH, frequency / time resource allocation information for higher layer control messages such as a random access response (RAR) transmitted on the PDSCH, a transmission power control command, information on activation / deactivation of SPS / CS (Configured Scheduling), etc. Various DCI formats are provided depending on the information in the DCI.

[0104] Table 5 illustrates DCI formats transmitted via the PDCCH.

[0105] [Table 5]

[0106] DCI format 0_0 is used to schedule a TB-based (or TB-level) PUSCH, and DCI format 0_1 ​​can be used to schedule a TB-based (or TB-level) PUSCH or a CBG-based (or CBG-level) PUSCH. DCI format 1_0 is used to schedule a TB-based (or TB-level) PDSCH, and DCI format 1_1 can be used to schedule a TB-based (or TB-level) PDSCH or a CBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0 / 0_1 may be referred to as UL grant DCI or UL scheduling information, and DCI format 1_0 / 1_1 may be referred to as DL grant DCI or UL scheduling information. DCI format 2_0 is used to convey dynamic slot format information (e.g., dynamic SFI) to a terminal, and DCI format 2_1 is used to convey downlink pre-emption information to a terminal. DCI format 2_0 and / or DCI format 2_1 can be transmitted to terminals in a group via a group common PDCCH, which is a PDCCH transmitted to terminals defined as one group.

[0107] The PDCCH / DCI includes a cyclic redundancy check (CRC), and the CRC is masked / scrambled with various identifiers (Radio Network Temporary Identifier, RNTI) depending on the owner or use of the PDCCH. For example, if the PDCCH is for a specific terminal, the CRC is masked with a Cell-RNTI (C-RNTI). If the PDCCH is related to paging, the CRC is masked with a P-RNTI (Paging-RNTI). If the PDCCH is related to system information (e.g., System Information Block, SIB), the CRC is masked with a System Information RNTI (SI-RNTI). If the PDCCH is related to a random access response, the CRC is masked with a Random Access-RNTI (RA-RNTI).

[0108] Table 6 illustrates the use and transmission channel of the PDCCH according to the RNTI. The transmission channel indicates the transmission channel associated with the data carried by the PDSCH / PUSCH scheduled by the PDCCH.

[0109] [Table 6]

[0110] The modulation method of the PDCCH is fixed (e.g., Quadrature Phase Shift Keying, QPSK), and one PDCCH consists of 1, 2, 4, 8, or 16 CCEs (Control Channel Elements) depending on the AL (Aggregation Level). One CCE consists of six REGs (Resource Element Groups). One REG is defined by one OFDMA symbol and one (P)RB.

[0111] The PDCCH is transmitted via a Control Resource Set (CORESET). The CORESET corresponds to a physical resource / parameter set used to carry the PDCCH / DCI in the BWP. For example, the CORESET includes a REG set having a given numerology (e.g., SCS, CP length, etc.). The CORESET can be configured via system information (e.g., MIB) or UE-specific higher layer (e.g., RRC) signaling. Examples of parameters / information used to configure the CORESET are as follows: One or more CORESETs can be configured for one UE, and multiple CORESETs can overlap in the time / frequency domain.

[0112] -controlResourceSetId: Indicates the identification information (ID) of the CORESET.

[0113] -frequencyDomainResources: Represents the frequency domain resources of CORESET. It is indicated via a bitmap, and each bit corresponds to an RB group (= 6 consecutive RBs). For example, the MSB (Most Significant Bit) 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.

[0114] -duration: represents the time domain resource of CORESET. It represents the number of consecutive OFDMA symbols that make up CORESET. For example, duration has a value of 1 to 3.

[0115] -cce-REG-MappingType: Represents the CCE-to-REG mapping type. Interleaved and non-interleaved types are supported.

[0116] -precoderGranularity: represents the precoder granularity in the frequency domain.

[0117] -tci-StatesPDCCH: Information indicating the TCI (Transmission Configuration Indication) state for the PDCCH (e.g., TCI-StateID). The TCI state is used to provide the Quasi-Co-Location (QCL) relationship between DL RSs and PDCCH DMRS ports in the RS set (TCI state).

[0118] -tci-PresentInDCI: Indicates whether the TCI field in the DCI is included.

[0119] -pdcch-DMRS-ScramblingID: represents information used to initialize the PDCCH DMRS scrambling sequence.

[0120] For PDCCH reception, the UE can monitor (e.g., blind decode) a set of PDCCH candidates in the CORESET. A PDCCH candidate represents a CCE that the UE monitors for PDCCH reception / detection. PDCCH monitoring can be performed in one or more CORESETs on an active DL BWP in each activated cell where PDCCH monitoring is configured. The set of PDCCH candidates that the UE monitors 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.

[0121] Table 7 illustrates the PDCCH search space.

[0122] [Table 7]

[0123] The SS sets can be configured via system information (e.g., MIB) or UE-specific higher layer (e.g., RRC) signaling. Up to S (e.g., 10) SS sets can be configured for each DL BWP of the serving cell. For example, the following parameters / information can be provided for each SS set: Each SS set is associated with one CORESET, and each CORESET configuration can be associated with one or more SS sets.

[0124] -searchSpaceId: Represents the ID of the SS set.

[0125] -controlResourceSetId: Represents the CORESET associated with the SS set.

[0126] - monitoringSlotPeriodicityAndOffset: Represents the PDCCH monitoring periodicity interval (slot unit) and the PDCCH monitoring period offset (slot unit).

[0127] -monitoringSymbolsWithinSlot: Represents the first OFDMA symbol for PDCCH monitoring within a slot where PDCCH monitoring is configured. It is indicated via a bitmap, and each bit corresponds to each OFDMA symbol within the slot. The MSB of the bitmap corresponds to the first OFDMA symbol within the slot. The OFDMA symbol corresponding to the bit with a bit value of 1 corresponds to the first symbol of CORESET within the slot.

[0128] -nrofCandidates:AL={1,2,4,8,16} represents the number of different PDCCH candidates (for example, one of the values ​​0, 1, 2, 3, 4, 5, 6, or 8).

[0129] -searchSpaceType: Indicates whether the SS type is CSS or USS.

[0130] DCI format: Indicates the DCI format of the PDCCH candidate.

[0131] Based on the CORESET / SS set configuration, the terminal can monitor PDCCH candidates in one or more SS sets within a slot. An opportunity (e.g., a time / frequency resource) during which the terminal must monitor PDCCH candidates is defined as a PDCCH (monitoring) opportunity. One or more PDCCH (monitoring) opportunities can be configured within a slot.

[0132] Uplink (DL) physical channels / signals

[0133] (1) PUSCH

[0134] The PUSCH carries uplink data (such as a 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. When the PUSCH is transmitted based on a DFT-s-OFDM waveform, the UE transmits the PUSCH by applying transform precoding. For example, if transform precoding is not possible (e.g., transform precoding is disabled), the UE may transmit the PUSCH based on the CP-OFDM waveform, and if transform precoding is possible (e.g., transform precoding is enabled), the UE may transmit the PUSCH based on the CP-OFDM waveform or the DFT-s-OFDM waveform. The PUSCH can be dynamically scheduled by the PDCCH (dynamic scheduling) or semi-statically scheduled based on higher layer (e.g., RRC) signaling (and / or Layer 1 (L1) signaling (e.g., PDCCH)) (Configured Scheduling, CS). Thus, in dynamic scheduling, PUSCH transmission is accompanied by PDCCH, while in CS, PUSCH transmission is not accompanied by PDCCH. CS includes Type-1 CG (Configured Grant) PUSCH transmission and Type-2 CG PUSCH transmission. In Type-1 CG, all parameters for PUSCH transmission are signaled by higher layers. In Type-2 CG, some parameters for PUSCH transmission are signaled by higher layers, and the rest are signaled by PDCCH. Essentially, in CS, PUSCH transmission is not accompanied by PDCCH.

[0135] (2) PUCCH

[0136] The PUCCH carries Uplink Control Information (UCI), which includes:

[0137] - SR (Scheduling Request): Information used to request UL-SCH resources.

[0138] HARQ-ACK (Hybrid Automatic Repeat and reQuest Acknowledgement): A reception acknowledgement signal for a DL signal (e.g., PDSCH, SPS disabled PDCCH). The HARQ-ACK response can include positive ACK (simply ACK), negative ACK (NACK), DTX (Discontinuous Transmission), or NACK / DTX. HARQ-ACK can be mixed with A / N, ACK / NACK, HARQ-ACK / NACK, etc. HARQ-ACK can be generated on a TB-by-TB basis / CBG-by-CBG basis. CSI (Channel Status Information): Feedback information for a DL channel. CSI includes CQI (Channel Quality Information), RI (Rank Indicator), PMI (Precoding Matrix Indicator), PTI (Precoding Type Indicator), etc.

[0139] Table 8 shows an example of a 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), and transmission structure. The PUCCH format can be classified into Short PUCCH (formats 0 and 2) and Long PUCCH (formats 1, 3, and 4) according to the transmission length.

[0140] [Table 8]

[0141] (0) PUCCH Format 0 (PF0)

[0142] -Supported UCI payload size: up to K bits (e.g., K = 2)

[0143] Number of OFDM symbols constituting a single PUCCH: 1 to X symbols (e.g., X = 2)

[0144] - Transmission structure: Consists of only UCI signals without DM-RS, and transmits UCI status by selecting and transmitting one of multiple sequences

[0145] (1) PUCCH Format 1 (PF1)

[0146] -Supported UCI payload size: up to K bits (e.g., K = 2)

[0147] Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y = 4, Z = 14)

[0148] - Transmission structure: DM-RS and UCI are configured in TDM format on different OFDM symbols, and UCI is a form in which a specific sequence is multiplied by a modulation (e.g., QPSK) symbol. CDM is supported between multiple PUCCH resources (in the same RB) (according to PUCCH format 1) by applying CS (Cyclic Shift) / OCC (Orthogonal Cover Code) to both UCI and DM-RS.

[0149] (2) PUCCH Format 2 (PF2)

[0150] -Supported UCI payload size: more than K bits (e.g., K = 2)

[0151] Number of OFDM symbols constituting a single PUCCH: 1 to X symbols (e.g., X = 2)

[0152] Transmission structure: DMRS and UCI are configured / mapped in the same symbol in FDM format, and transmitted by applying only IFFT to the coded UCI bits without DFT.

[0153] (3) PUCCH Format 3 (PF3)

[0154] -Supported UCI payload size: more than K bits (e.g., K = 2)

[0155] Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y = 4, Z = 14)

[0156] - Transmission structure: DMRS and UCI are configured / mapped to different symbols in TDM format, and the coded UCI bits are transmitted after applying DFT. OCC is applied to UCI before DFT, and CS (or IFDM mapping) is applied to DMRS, supporting multiplexing to multiple terminals.

[0157] (4) PUCCH Format 4 (PF4)

[0158] -Supported UCI payload size: more than K bits (e.g., K = 2)

[0159] Number of OFDM symbols constituting a single PUCCH: Y to Z symbols (e.g., Y = 4, Z = 14)

[0160] Transmission structure: DMRS and UCI are configured / mapped to different symbols in TDM format, and the coded UCI bits are transmitted between terminals without multiplexing by applying DFT.

[0161] SSB (Synchronization Signal Block) transmission and related operations

[0162] Figure 9 shows a structure of a synchronization signal and broadcast channel block (SSB) applicable to the present disclosure. Figure 9 illustrates an example of an SSB structure. A terminal can perform cell search, system information acquisition, beam alignment for initial connection, DL measurement, etc. based on the SSB. The SSB is used together with a synchronization signal / physical broadcast channel (SS / PBCH) block.

[0163] Referring to Figure 9, an SSB consists of a PSS, SSS, and PBCH. The SSB is configured with four consecutive OFDM symbols, and the PSS, PBCH, SSS / PBCH, and PBCH are transmitted in each OFDM symbol. The PSS and SSS each consist of one OFDM symbol and 127 subcarriers, and the PBCH consists of three OFDM symbols and 576 subcarriers. Polar coding and Quadrature Phase Shift Keying (QPSK) are applied to the PBCH. The PBCH consists of data REs and Demodulation Reference Signal (DMRS) REs for each OFDM symbol. There are three DMRS REs per RB, and three data REs exist between the DMRS REs.

[0164] Cell search

[0165] Cell search refers to a process in which a terminal acquires time / frequency synchronization of a cell and detects the cell ID (identifier) ​​(e.g., physical layer cell ID, PCID) of the cell. The PSS is used to detect a cell ID within a cell ID group, and the SSS is used to detect a cell ID group. The PBCH is used for SSB (time) index detection and half-frame detection.

[0166] The cell search process of the terminal is summarized in Table 9 below.

[0167] [Table 9]

[0168] There are 336 cell ID groups, and each cell ID group has 3 cell IDs, for a total of 1008 cell IDs, which can be defined by Equation 3.

[0169] [Formula 3]

number

[0170] where: JPEG2025534341000020.jpg9130 indicates a cell ID (e.g., PCID). JPEG2025534341000021.jpg11135 indicates the cell ID group and is provided / obtained via SSS. JPEG2025534341000022.jpg10152 indicates the cell ID within the cell ID group and is provided / obtained via PSS.

[0171] PSS sequence JPEG2025534341000023.jpg10137 can be defined to satisfy Equation 4.

[0172] [Formula 4]

number

[0173] JPEG2025534341000025.jpg37150

[0174] SSS Sequence JPEG2025534341000026.jpg8134 can be defined to satisfy Equation 5.

[0175] [Formula 5]

number

[0176] JPEG2025534341000028.jpg49139

[0177] FIG. 10 illustrates SSB transmission applicable to the present disclosure. SSBs are transmitted periodically in accordance with the SSB periodicity. The SSB basic period assumed by a terminal during initial cell search is defined as 20 ms. After cell connection, the SSB can be set to one of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms} by the network (e.g., base station). An SSB burst set is configured at the beginning of the SSB period. The SSB burst set is configured in a 5 ms time window (i.e., half frame), and an SSB can be transmitted a maximum of L times within the SSB burst set. The maximum number of SSB transmissions, L, is given as follows depending on the frequency band of the carrier: One slot contains a maximum of two SSBs.

[0178] -For frequency range up to 3GHz, L=4

[0179] -For frequency range from 3GHz to 6GHz, L=8

[0180] -For frequency range from 6GHz to 52.6GHz, L=64

[0181] The time position of a candidate SSB within an SSB burst set can be defined by the SCS as follows: The time position of the candidate SSB is indexed (SSB index) from 0 to L-1 in time order within the SSB burst set (i.e., half frame). In this specification, the terms candidate SSB and SSB candidate are used interchangeably.

[0182] - Case A - 15kHz SCS: The index of the starting symbol of the candidate SSB is given by {2,8}+14*n.

[0183] -For operation without shared spectrum channel access (e.g., 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.

[0184] -For operation with shared spectrum channel access (e.g., U-band, UCell): n = 0, 1, 2, 3, 4.

[0185] Case B - 30kHz SCS: The index of the starting symbol of the candidate SSB is given by {4, 8, 16, 20} + 28*n. If the carrier frequency is 3GHz or less, n = 0. If the carrier frequency is 3GHz to 6GHz, n = 0, 1.

[0186] - Case C-30kHz SCS: The index of the starting symbol of the candidate SSB is given by {2, 8}+14*n.

[0187] -If shared spectrum channel connection operation is not performed / supported: (1) For paired spectrum operation, if the carrier frequency is less than or equal to 3 GHz, n = 0, 1. If the carrier frequency is within FR1 and greater than 3 GHz, n = 0, 1, 2, 3. (2) For unpaired spectrum operation, if the carrier frequency is less than or equal to 2.4 GHz, n = 0, 1. If the carrier frequency is within FR1 and greater than 2.4 GHz, n = 0, 1, 2, 3.

[0188] -When shared spectrum channel access operation is performed / supported: n=0, 1, 2, 3, 4, 6, 7, 8, 9.

[0189] Case D-120kHz SCS: The index of the starting symbol of the candidate SSB is given by {4, 8, 16, 20}+28*n, where n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 for carrier frequencies in FR2.

[0190] Case E-240kHz SCS: The index of the starting symbol of the candidate SSB is given by {8, 12, 16, 20, 32, 36, 40, 44}+56*n, where n=0, 1, 2, 3, 5, 6, 7, 8 for carrier frequencies in FR2.

[0191] JPEG2025534341000029.jpg93163

[0192] [Table 10]

[0193] JPEG2025534341000031.jpg52162

[0194] FIG. 11 shows an example of SSB candidate positions applicable to the present disclosure. FIG. 11 illustrates a case where Q is 4 and ssb-PositionsInBurst is set to "10100000." In this case, only SSBs with SSB (SS / PBCH block) indexes #0 and #2 can be transmitted. ssb-PositionsInBurst and Q can be used to provide a rate matching pattern within a Discovery Reference Signal (DRS) transmission window (or discovery burst transmission window). For example, a terminal can perform rate matching on the actually transmitted SSB index provided by ssb-PositionsInBurst and all QCL-defined SSB candidate position indexes. In FIG. 11, the terminal can perform rate matching on time / frequency resources with SSB candidate position indexes 0, 2, 4, 6, 8, 10, 12, 14, 16, and 18. Therefore, when receiving a PDSCH scheduled by a PDCCH CRC-scrambled by the C-RNTI, MCS-C-RNTI, CS-RNTI, RA-RNTI, MsbB-RNTI, P-RNTI, or TC-RNTI (or scrambled by the PDSCH with SPS (or with CRC) and the system information indicator in the PDCCH (i.e., DCI) is set to 1), the terminal can assume SSB transmission according to ssb-PositionsInBurst if the PDSCH resource allocation overlaps with a PRB including SSB transmission resources (e.g., SS / PBCH block candidate position indices (0 / 2 / 4 / 6 / 8 / 10 / 12 / 14 / 16 / 18)). That is, the terminal can assume that the PRB including the SSB transmission resource in the OFDM symbol in which the SSB is transmitted is not available for PDSCH (i.e., not mapped).

[0195] FIG. 12 illustrates an example of downlink time synchronization information applicable to the present disclosure. FIG. 12 illustrates a terminal acquiring information related to downlink time synchronization. The terminal can acquire downlink synchronization by detecting SSBs. The terminal can identify the structure of the SSB burst set based on the detected SSB index, thereby detecting symbol / slot / half-frame boundaries. The frame / half-frame number to which the detected SSB belongs can be identified using SFN information and half-frame indication information.

[0196] Specifically, the terminal can acquire 10-bit SFN (System Frame Number) information from the PBCH (s0 to s9). Of 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).

[0197] Next, the terminal can obtain 1-bit half-frame indication information (c0). If the carrier frequency is 3 GHz or less, the half-frame indication information can be implicitly signaled using the PBCH DMRS. The PBCH DMRS indicates 3-bit information by using one of the eight PBCH DMRS sequences. Therefore, when L=4, of the 3 bits that can be indicated using the eight PBCH DMRS sequences, the remaining 1 bit indicates the SSB index and can be used for half-frame indication.

[0198] Finally, the terminal can obtain an SSB index based on the DMRS sequence and the PBCH payload. SSB candidates are indexed from 0 to L-1 in time order within an SSB burst set (i.e., a half-frame). When L = 8 or 64, the three least significant bits (LSBs) of the SSB index can be indicated using eight different PBCH DMRS sequences (b0 to b2). When L = 64, the three most significant bits (MSBs) of the SSB index are indicated via the PBCH (b3 to b5). When L = 2, the two least significant bits of the SSB index can be indicated using four different PBCH DMRS sequences (b0, b1). When L = 4, of the three bits that can be indicated using eight PBCH DMRS sequences, the remaining bit after indicating the SSB index can be used to indicate a half-frame (b2).

[0199] Getting System Information

[0200] 13 illustrates a system information (SI) acquisition process. A UE can acquire AS- / NAS-information through the SI acquisition process. The SI acquisition process is applicable to UEs in the RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED states.

[0201] SI is divided into MIB (Master Information Block) and multiple SIBs (System Information Blocks). SI other than MIB is called RMSI (Remaining Minimum System Information). For details, please refer to the following.

[0202] -MIB contains information / parameters related to the reception of SIB1 (System Information Block Type 1) and is transmitted via the PBCH of the SSB.

[0203] -MIB contains information / parameters related to the reception of SIB1 (System Information Block Type 1) and is transmitted via the PBCH of SSB. MIB information may refer to 3GPP TS 38.331 and may include the following fields:

[0204] -subCarrierSpacingCommon ENUMERATED{scs15or60,scs30or120},

[0205] -ssb-SubcarrierOffset INTEGER(0..15),

[0206] -pdcch-ConfigSIB1 INTEGER(0..255),

[0207] -dmrs-TypeA-Position ENUMERATED{pos2,pos3},

[0208] ...

[0209] -spare BIT STRING(SIZE(1))

[0210] See Table 11 for a description of each field.

[0211] [Table 11]

[0212] During initial cell selection, the terminal assumes that half frames with SSBs are repeated at a period of 20 ms. The terminal can check whether a CORESET (Control Resource Set) (e.g., CORESET #0) for the Type 0-PDCCH common search space exists based on the MIB. SSB <=23(for FR1) or k SSBIf k <= 11 (for FR2), the terminal can determine that a CORESET for the Type0-PDCCH common search space exists. SSB >23(for FR1) or k SSB >11 (for FR2), the UE may 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 and is used to transmit a PDCCH that schedules SI messages. If the Type0-PDCCH common search space exists, the UE may determine (i) a plurality of consecutive RBs and one or more consecutive symbols constituting a CORESET (e.g., CORESET#0) and (ii) a PDCCH opportunity (i.e., a time-domain location for PDCCH reception) (e.g., search space#0) based on information in the MIB (e.g., pdcch-ConfigSIB1). If the Type0-PDCCH common search space does not exist, pdcch-ConfigSIB1 provides information about the frequency location where SSB / SIB1 exists and the frequency range where SSB / SIB1 does not exist.

[0213] SIB1 includes information related to the availability and scheduling (e.g., transmission period, SI-window size) of the remaining SIBs (hereinafter, SIBx, where x is an integer equal to or greater than 1). For example, SIB1 may indicate whether SIBx is broadcast periodically or provided in response to a terminal request in an on-demand manner. If SIBx is provided in an on-demand manner, SIB1 may include information necessary for the terminal to perform an SI request. SIB1 is transmitted via a PDSCH, and a PDCCH that schedules SIB1 is transmitted via a Type0-PDCCH common search space, and SIB1 is transmitted via a PDSCH indicated by the PDCCH.

[0214] The SIBx are included in SI messages and transmitted via the PDSCH. Each SI message is transmitted within a periodically occurring time window (i.e., an SI window).

[0215] beam alignment

[0216] FIG. 14 shows an example of multi-beam transmission that can be applied to the present disclosure.

[0217] Beam sweeping refers to a Transmission Reception Point (TRP) (e.g., a base station / cell) varying the beam (direction) of a radio signal over time (hereinafter, the terms beam and beam direction may be used interchangeably). SSBs can be transmitted periodically using beam sweeping. In this case, the SSB index is implicitly linked to the SSB beam. The SSB beam is changed either on an SSB (index) basis or on an SSB (index) group basis. In the latter case, the SSB beam remains the same within the SSB (index) group. That is, the transmission beam direction of the SSB is repeated for multiple consecutive SSBs. The maximum number of SSB transmissions L within an SSB burst set is 4, 8, or 64, depending on the frequency band to which the carrier belongs. Therefore, the maximum number of SSB beams within an SSB burst set is also given as follows, depending on the frequency band of the carrier:

[0218] -For frequency range up to 3GHz, Max number of beams=4

[0219] -For frequency range from 3GHz to 6GHz, Max number of beams=8

[0220] -For frequency range from 6GHz to 52.6GHz, Max number of beams=64

[0221] *If multi-beam transmission is not applied, the number of SSB beams is one.

[0222] When a terminal attempts initial connection to a base station, the terminal can align a beam with the base station based on the SSB. For example, the terminal performs SSB detection and then identifies the best SSB. The terminal can then transmit a RACH preamble to the base station using a PRACH resource linked to / corresponding to the index (i.e., beam) of the best SSB. The SSB can also be used to align beams between the base station and the terminal after initial connection.

[0223] Channel Measurement and Rate-Matching

[0224] FIG. 15 shows an example of indicating an actually transmitted SSB (SSB_tx) that can be applied to the present disclosure.

[0225] A maximum of L SSBs can be transmitted within an SSB burst set, and the number / positions at which the SSBs are actually transmitted may vary for each base station / cell. The number / positions at which the SSBs are actually transmitted are used for rate matching and measurement, and information about the actually transmitted SSBs (e.g., ssb-PositionsInBurst) is indicated as follows:

[0226] - In the case of rate matching, it can be indicated via UE-specific RRC signaling or RMSI. UE-specific RRC signaling includes a full (e.g., length L) bitmap in both the frequency ranges below 6 GHz and above 6 GHz. Meanwhile, RMSI includes the full bitmap below 6 GHz and a compressed bitmap above 6 GHz as shown. Specifically, information about the actually transmitted SSB can be indicated using a group-bitmap (8 bits) + a bitmap within the group (8 bits). Here, resources (e.g., REs) indicated via UE-specific RRC signaling or RMSI are reserved for SSB transmission, and PDSCH / PUSCH, etc. can be rate-matched taking the SSB resources into consideration.

[0227] - Measurement-related: In RRC connected mode, the network (e.g., base station) can indicate the SSB set to be measured within the measurement interval. The SSB set can be indicated per frequency layer. If there is no indication regarding the SSB set, a default SSB set is used. The default SSB set includes all SSBs within the measurement interval. The SSB set can be indicated using a full (e.g., length L) bitmap in RRC signaling. In RRC idle mode, the default SSB set is used.

[0228] Random Access (RA) process

[0229] General Procedure

[0230] The random access procedure is used for various purposes. For example, the random access procedure can be used for network initial connection, handover, and UE-triggered UL data transmission. A UE can acquire 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 or dedicated procedure. The random access procedure is also used interchangeably with the Random Access Channel (RACH) procedure.

[0231] FIG. 16 illustrates an example of a collision-based random access procedure applicable to the present disclosure. Referring to FIG. 16, a terminal receives information regarding random access from a base station via system information. Thereafter, if random access is required, the terminal transmits 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 transmits a random access response (RAR) message (message 2) to the terminal (S720). Specifically, scheduling information for the random access response message may be CRC-masked with the random access-RNTI (RA-RNTI) and transmitted on an L1 / L2 control channel (PDCCH). The PDCCH masked with the RA-RNTI can only be transmitted via a common search space (CSS). When the terminal receives a scheduling signal masked with the RA-RNTI, the terminal may receive a random access response message from a PDSCH indicated by the scheduling information. The terminal then checks whether the random access response message contains the random access response information indicated to the terminal. The presence of the random access response information designated to the terminal can be confirmed by checking whether a Random Access Preamble ID (RAID) for the preamble transmitted by the terminal exists. The random access response information includes timing offset information (e.g., Timing Advance Command, TAC) for UL synchronization, UL scheduling information (e.g., UL grant), and terminal temporary identification information (e.g., Temporary-C-RNTI, TC-RNTI). If the random access response information is received, the terminal transmits UL-SCH (Shared Channel) data (message 3) via a PUSCH according to the UL scheduling information (S730). After receiving the UL-SCH data, the base station transmits a contention resolution message (message 4) to the terminal (S740).

[0232] 17 shows an example of a non-contention-based random access procedure that can be applied to the present disclosure. The non-contention-based random access procedure can be used in a handover process or can exist when required by a base station command. The basic procedure is the same as the contention-based random access procedure.

[0233] Referring to Figure 17, a terminal is assigned a dedicated random access preamble from a base station (S810). Dedicated random access preamble indication information (e.g., a preamble index) may be included in an RRC message (e.g., a handover command) or may be received via a PDCCH order. After initiating the random access procedure, the terminal transmits the dedicated random access preamble to the base station (S820). Thereafter, the terminal receives a random access response from the base station (S830) and terminates the random access procedure. The random access procedure on an SCell can only be initiated by a PDCCH order.

[0234] In NR, DCI format 1_0 is used to start a non-collision-based random access procedure with a PDCCH order. DCI format 1_0 is used to schedule a PDSCH in one DL cell. Meanwhile, when the CRC (Cyclic Redundancy Check) of DCI format 1_0 is scrambled with the C-RNTI and the bit values ​​of the 'Frequency domain resource assignment' field are all 1, DCI format 1_0 is used as a PDCCH order to indicate a random access procedure. In this case, the fields of DCI format 1_0 are set as follows:

[0235] -RA preamble index: 6 bits

[0236] -UL / SUL (Supplementary UL) indicator: 1 bit. If the bit value of the RA preamble index is not all 0 and SUL is set in the cell for the terminal, it indicates the UL carrier on which the PRACH is transmitted in the cell. Otherwise, it is reserved.

[0237] SSB index: 6 bits. If the bit value of the RA preamble index is not all 0, it indicates the SSB used to determine the RACH opportunity for PRACH transmission. Otherwise, it is reserved.

[0238] PRACH Mask Index: 4 bits. If the bit value of the RA Preamble Index is not all 0, it indicates the RACH opportunity associated with the SSB indicated by the SSB Index. Otherwise, it is reserved.

[0239] -Reserved: 10 bits

[0240] If DCI format 1_0 does not correspond to a PDCCH command, DCI format 1_0 consists of fields used to schedule the PDSCH (e.g., Time domain resource assignment, MCS (Modulation and Coding Scheme), HARQ process number, PDSCH-to-HARQ_feedback timing indicator, etc.).

[0241] Network connection and communication process

[0242] The terminal may perform a network access process. For example, the terminal may receive and store in memory system information and configuration information required to perform the procedures and / or methods described / proposed below while connecting to a network (e.g., a base station). The configuration information required for the present invention may be received via signaling in an upper layer (e.g., RRC layer; Medium Access Control, MAC, layer, etc.).

[0243] FIG. 18 shows an example of a network initial connection and communication procedure applicable to the present disclosure. Physical channels and reference signals in NR can be transmitted using beamforming. If beamforming-based signal transmission is supported, a beam management process may be involved to align beams between a base station and a terminal. Furthermore, signals proposed in the present invention can be transmitted / received using beamforming. In Radio Resource Control (RRC) IDLE mode, beam alignment can be performed based on SSB. Meanwhile, in RRC CONNECTED mode, beam alignment can be performed based on CSI-RS (in DL) and SRS (in UL). Meanwhile, if beamforming-based signal transmission is not supported, beam-related operations can be omitted in the following description.

[0244] Referring to FIG. 18, a base station (e.g., BS) may periodically transmit SSBs (S1802). Here, the SSBs include PSS / SSS / PBCH. The SSBs may be transmitted using beam sweeping (see FIG. 14). Then, the base station may transmit RMSI (Remaining Minimum System Information) and OSI (Other System Information) (S1804). The RMSI may include information (e.g., PRACH configuration information) required for the terminal to initially connect to the base station. Meanwhile, the terminal identifies the best SSB after performing SSB detection. Then, the terminal may transmit a RACH preamble (Message 1, Msg 1) to the base station using a PRACH resource linked / 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) can be set via system information (e.g., RMSI). Then, as part of the RACH process, the base station transmits a Random Access Response (RAR) (Msg2) in response to the RACH preamble (S1808), the terminal transmits Msg3 (e.g., an RRC Connection Request) using the UL grant in the RAR (S1810), and the base station can transmit a contention resolution message (Msg4) (S1812). Msg4 can include an RRC Connection Setup.

[0245] Once an RRC connection is established between the base station and the terminal through the RACH procedure, subsequent beam alignment can be performed based on SSB / CSI-RS (in DL) and SRS (in UL). For example, the terminal may receive SSB / CSI-RS (S1814). The SSB / CSI-RS can be used by the terminal to generate a beam / CSI report. Meanwhile, the base station may request a beam / CSI report from the terminal via DCI (S1816). In this case, the terminal may generate a beam / CSI report based on the SSB / CSI-RS and transmit the generated beam / CSI report to the base station via PUSCH / PUCCH (S1818). The beam / CSI report may include information about a preferred beam, a beam measurement result, etc. The base station and the terminal may switch beams based on the beam / CSI report (S1820a, S1820b).

[0246] The terminal and the base station can then perform procedures and / or methods described / proposed hereinafter. For example, the terminal and the base station can process information in memory and transmit a radio signal according to the proposal of the present invention based on configuration information obtained in a network connection process (e.g., a system information acquisition process, an RRC connection process via RACH, etc.), or process a received radio signal and store it in memory. Here, the radio signal may include at least one of a PDCCH, a PDSCH, and a Reference Signal (RS) in the downlink, and at least one of a PUCCH, a PUSCH, and an SRS in the uplink.

[0247] DRX (Discontinuous Reception) operation

[0248] The terminal can perform DRX operation. A terminal configured for DRX can reduce power consumption by discontinuously receiving DL signals. DRX can be performed in the RRC (Radio Resource Control)_IDLE state, RRC_INACTIVE state, and RRC_CONNECTED state. In the RRC_IDLE state and RRC_INACTIVE state, DRX is used to discontinuously receive paging signals. Below, DRX performed in the RRC_CONNECTED state (RRC_CONNECTED DRX) will be described.

[0249] FIG. 19 shows an example of a DRX cycle applicable to the present disclosure (RRC_CONNECTED state).

[0250] Referring to FIG. 19, a DRX cycle consists of On Duration and Opportunity for DRX. The DRX cycle defines the time interval during which On Duration is periodically repeated. On Duration indicates the time period during which the UE monitors to receive the PDCCH. When DRX is configured, the UE monitors the PDCCH during On Duration. If a PDCCH is successfully detected during PDCCH monitoring, the UE operates the inactivity timer and maintains an awake state. On the other hand, if a PDCCH is not successfully detected during PDCCH monitoring, the UE enters a sleep state after the On Duration expires. Therefore, when DRX is configured, PDCCH monitoring / reception can be performed discontinuously in the time domain when performing the above / proposed procedures and / or methods. For example, when DRX is configured, PDCCH reception opportunities (e.g., slots having a PDCCH search space) in the present invention can be set to be discontinuous according to the DRX configuration. On the other hand, when DRX is not configured, PDCCH monitoring / reception can be performed continuously in the time domain when performing the above-described / proposed procedures and / or methods. For example, when DRX is not configured, in the present invention, PDCCH reception opportunities (e.g., slots having PDCCH search spaces) can be configured continuously. Meanwhile, regardless of whether DRX is configured, PDCCH monitoring can be restricted in the time interval configured for the measurement gap.

[0251] Table 12 shows the process of the UE related to DRX (RRC_CONNECTED state). Referring to Table 12, DRX configuration information is received via higher layer (e.g., RRC) signaling, and DRX ON / OFF is controlled by a DRX command in the MAC layer. When DRX is configured, the UE can perform PDCCH monitoring discontinuously when performing the procedures and / or methods described / proposed in the present invention, as illustrated in FIG. 19.

[0252] [Table 12]

[0253] Here, MAC-CellGroupConfig includes configuration information necessary for setting MAC (Medium Access Control) parameters for a cell group. MAC-CellGroupConfig may also include configuration information related to DRX. For example, MAC-CellGroupConfig may include information necessary for defining DRX as follows:

[0254] - Value of drx-OnDurationTimer: Defines the length of the start period of the DRX cycle

[0255] Value of drx-InactivityTimer: defines the length of the time interval in which the UE is awake after a PDCCH opportunity in which a PDCCH indicating initial UL or DL ​​data is detected

[0256] - Value of drx-HARQ-RTT-TimerDL: Defines the maximum time interval between when a DL initial transmission is received and when a DL retransmission is received

[0257] - Value of drx-HARQ-RTT-TimerDL: Defines the maximum time interval from when a grant for UL initial transmission is received until when a grant for UL retransmission is received

[0258] -drx-LongCycleStartOffset: Defines the length and start of a DRX cycle

[0259] -drx-ShortCycle (optional): Defines the time length of a short DRX cycle

[0260] Here, if any of the drx-OnDurationTimer, drx-InactivityTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerDL is operating, the terminal performs PDCCH monitoring at each PDCCH opportunity while remaining in an awake state.

[0261] Specific Examples of the Disclosure

[0262] The present disclosure is for dynamically changing a primary cell (PCell) in a wireless communication system, and proposes a technique for changing the PCell based on a PCell change-related instruction. Specifically, the present disclosure describes a procedure for changing the PCell and various embodiments related to the PCell change.

[0263] Energy conservation in base stations can contribute to building environmentally friendly networks by reducing carbon emissions and reducing operational expenditures (OPEX) for telecommunications companies. Therefore, energy conservation in base stations is considered important in wireless communication systems, including 3GPP. In particular, with the introduction of 5G, which requires high transmission rates, base stations must be equipped with more antennas and provide services over wider bandwidths and frequency bands. As a result, research results have been published showing that base station energy costs have reached 20% of total OPEX. In response to growing interest in energy conservation in base stations, a new study item (SI) called "study on network energy savings" was approved in 3GPP NR release 18.

[0264] Specifically, enhancement techniques have been considered to improve energy saving capabilities, i.e., network energy saving (NES), from the perspective of base station transmission and reception. For example, methods have been considered to achieve dynamic and / or semi-statically efficient operation in one or more network energy saving techniques in the time, frequency, space, and power domains that utilize potential assistance / feedback from UEs (user equipments) and potential UE assistance information, and to achieve finer granularity adaptation of transmission and / or reception.

[0265] For the purpose of NES, the base station may activate a technique for adjusting on / off for a certain duration on the time axis, adjusting transmission / reception resources for UE-common or UE-specific signals / channels, changing the amount of frequency axis resources, adjusting transmission power, or turning on / off antenna ports or transmission reception points (TRPs) in the spatial domain. Hereinafter, in this disclosure, a state in which the above-mentioned NES-related technologies (hereinafter referred to as "NES technologies") are applied is referred to as an NES mode or NES state. Hereinafter, in this disclosure, according to Approach 1, the base station may inform the terminal which NES technology is applied for each NES technology or NES technology group. Alternatively, according to Approach 2, the base station can pre-configure a corresponding NES technology or NES technology group for each code point of a specific indicator (e.g., an indicator indicated via DCI or MAC CE, or an indicator set by higher layer signaling).

[0266] In approach 1, if at least one NES technology is applied, the terminal may define the corresponding state as an NES mode or an NES state. Alternatively, depending on which NES technology is applied, the terminal may define different NES modes or different NES states as being applied. In approach 2, the terminal may define the corresponding state according to the NES technology associated with the indicator. For example, if a 1-bit indicator is used, and an NES technology corresponding to "0" is not associated, and one or more NES technologies corresponding to "1" are associated, the terminal may define the corresponding state as an NES mode or an NES state when an indicator with a value of "1" is received. As another example, if a 2-bit indicator is used, and an NES technology corresponding to "00" is not associated, and one or more NES technologies_A are associated, and "01" is associated, and one or more NES technologies_B are associated, and "10" is associated, and one or more NES technologies_C are associated, and an indicator with a code point other than "00" is received, the terminal may define the corresponding state as an NES mode or an NES state. In this case, the terminal can distinguish whether or not it is in an NES state for each code point, or which NES state it is in, by defining "01" as NES state #1, "10" as NES state #2, and "11" as NES state #3.

[0267] Meanwhile, a base station can operate multiple frequency bands and / or multiple carriers (or serving cells). Thus, the serving cell corresponding to frequency F1 can operate as a PCell for a first terminal (UE#1), and the serving cell corresponding to frequency F2 can operate as a PCell for a second terminal (UE#2). In this case, the base station must periodically transmit SSB and / or SIB1, etc. over F1 and F2 to operate the two serving cells as PCells. However, when the first terminal (UE#1) and the second terminal (UE#2) have no data to transmit and / or receive, or the amount of data to transmit and / or receive is small, it may be advantageous from the viewpoint of energy conservation of the base station to operate only one of the serving cells corresponding to F1 or F2. That is, when the PCell of the second terminal UE#2 is changed to a serving cell corresponding to F1 instead of F2, energy of the base station can be saved.

[0268] Therefore, the present disclosure proposes a method for dynamically changing the PCell. For convenience of the following description, the present disclosure may refer to a serving cell that has been operating as an existing PCell as PCell_old, and a serving cell that operates as a new PCell in response to a PCell change instruction from the base station as PCell_new.

[0269] According to an embodiment of the present disclosure, PCell change-related information may be dynamically signaled as shown in Fig. 20. Fig. 20 illustrates an example of a PCell change indication procedure in a wireless communication system according to an embodiment of the present disclosure. Fig. 20 illustrates signal exchange between a terminal 2010 and a base station 2020.

[0270] 20, in step S2001, the base station 2020 transmits instruction information regarding a PCell change to the terminal 2010. For example, the base station 2020 may dynamically transmit the instruction information regarding a PCell change via DCI, MAC CE, or the like.

[0271] In step S2003, the terminal 2010 changes the PCell based on the instruction information regarding the PCell change. That is, the terminal 2010 changes the PCell from PCell_old to PCell_new, and can perform at least some of the functions or operations that were being performed on the existing PCell_old on PCell_new. According to an embodiment, the at least some of the functions may include at least one of a function of monitoring a PDCCH on a CSS set, a random access procedure-related function, or a PUCCH transmission function. For example, by changing the PCell from PCell_old to PCell_new, the terminal 2010 can monitor the PDCCH configured to be monitored on the CSS set of PCell_new without monitoring the PDCCH configured to be monitored on the CSS set of PCell_old.

[0272] [Example #1] Example of signaling PCell change

[0273] A base station can instruct a terminal to change its PCell via DCI or MAC CE. The DCI or MAC CE instructing a PCell change can be transmitted UE-specific, UE group-common, or cell-specific. The DCI can be transmitted after being scrambled with an identifier (e.g., a Radio Network Temporary Identifier (RNTI)) set to be UE-specific, UE group-common, or cell-specific. The MAC CE can be transmitted via a scheduled PDSCH with the DCI scrambled with an identifier set to be UE-specific, UE group-common, or cell-specific. According to an embodiment, a bit location at which a PCell change is indicated in the MAC CE can be pre-configured.

[0274] 21 illustrates an example of a procedure for changing a PCell in a wireless communication system according to an embodiment of the present disclosure. 21 illustrates an operation method of a terminal.

[0275] 21, in step S2101, a terminal configures a PCell and an SCell and performs communication. That is, the terminal performs a random access procedure with a base station, configures a first serving cell of the base station as a PCell for carrier aggregation, and can add at least one other serving cell as an SCell. This allows the terminal to perform communication using multiple cells including a PCell and an SCell.

[0276] In step S2103, the UE receives an instruction for PCell change. That is, the UE may receive the instruction for PCell change via DCI or MAC CE. For example, the PCell change may be indicated using DCI indicating PUCCH cell switching, a PDCCH order, an SPS / CG configuration, an NES state, etc.

[0277] In step S2105, the UE performs a PCell change procedure. That is, the UE may perform a procedure to change the PCell from the first cell to the second cell based on the instruction for PCell change. Here, the second cell may or may not be one of the serving cells of the UE. The procedure to change the PCell may include at least one operation to enable the second cell to perform at least some of the functions that were performed in the first cell.

[0278] When a PCell change is indicated using DCI, at least one of the following embodiments may be applied.

[0279] Example #1-1) As shown in Table 13 below, a DCI indicating PUCCH cell switching may be used for a PCell change instruction. As an example, an indicator indicating PUCCH cell switching may be configured in a DCI format (e.g., DCI format 1_1 or DCI format 1_2). If the indicator is '0', the UE transmits the PUCCH via the PCell, and if the indicator is '1', the UE may transmit the PUCCH via a previously configured PUCCH-sSCell. According to an embodiment of the present disclosure, when the PUCCH cell switching indicator configured in the DCI format is used as a PCell change instruction, the UE may determine a cell in which at least some functions of the PCell should be performed based on the PUCCH cell switching indicator. For example, if the PUCCH cell switching indicator is '0', the UE maintains all functions of the PCell in the existing PCell, and if the PUCCH cell switching indicator is '1', the UE may perform at least some functions of the PCell in a previously configured PUCCH-sSCell. Whether the PUCCH cell switching indicator can be used as PCell change indication information can be configured in advance via higher layer signaling. Alternatively, the UE can determine whether the PUCCH cell switching indicator can be used as PCell change indication information based on whether the UE is in the NES state. For example, in the NES state, the UE can 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.

[0280] Table 13 shows the procedure for PUCCH cell switching excerpted from TS 38.213v17.3.0.

[0281] [Table 13]

[0282] Example #1-2) A PDCCH order can be used to indicate a PCell change. For example, a PDCCH order indicating the initiation of a random access procedure can be used to indicate a PCell change. The random access procedure can be initiated by a PDCCH order when DCI format 1_0 is scrambled with the C-RNTI and the frequency domain resource assignment (FDRA) field is all ones. As an example, a PCell change can be indicated via a bit, code point, or combination of code points in a specific field of the PDCCH order. For example, a random access preamble index field, an UL / SUL indicator field, an 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 UE can receive a PUCCH configuration for the PCell_new to be changed via higher layer signaling (e.g., a handover command) and transmit a PUCCH on the PCell_new in response to receiving the PDCCH order. That is, the terminal can notify the base station of a PCell change by transmitting a PUCCH on PCell_new without transmitting a PRACH in response to receiving a PDCCH order.

[0283] Example #1-3) When activation of the SPS / CG configuration of a specific index on a PCell or SCell is indicated, a PCell change can be performed. The specific index can be predefined or configured by higher layer signaling. For example, the specific index can be predefined as a lowest configuration index or a higher configuration index.

[0284] Example #1-4) PCell change can be performed when an NES state or a specific NES state is indicated. Or, when a specific DRX configuration (e.g., a cell-specific DTX and / or DRX configuration) is activated while multiple DRX configurations (e.g., cell-specific DTX and / or DRX configurations) are configured, PCell change can be performed. When an NES state is indicated, PCell change can be performed. Or, when switching to a specific BWP occurs on a PCell or SCell, PCell change can be performed. For example, when switching from BWP#1 to BWP#2 occurs on a PCell, the UE's existing PCell becomes PCell_old, and the pre-configured existing SCell can be changed to PCell_new.

[0285] In the above-described and below-described embodiments, the PCell may be replaced with a PSCell, i.e., in the present disclosure, the PCell may be understood as a PSCell, and the proposed embodiments may also be applied to the change of the PSCell.

[0286] Through the PCell change indication proposed in Examples #1-1 to #1-4, a certain SCell belonging to an SCG can be dynamically changed to a PCell or a PSCell. In the above-mentioned embodiments, there may be a plurality of candidate SCells that can be changed to a PCell. In this case, all serving cells excluding the PCell may be included in the candidate SCells, or some serving cells may be included in the candidate SCells. Whether each serving cell belongs to a candidate SCell may be configured and / or indicated by the base station. For example, whether a serving cell is a candidate SCell for PCell change may be indicated in the procedure for SCell addition. When a plurality of candidate SCells are configured, one SCell among the plurality of candidate SCells may be indicated via DCI or MAC CE, and the indicated one SCell may be changed to a PCell.

[0287] When a DCI or MAC CE indicating a PCell change is received, the UE may perform the PCell change operation after a certain time. That is, the UE may perform the PCell operation after delaying application for a certain time from the time when the DCI or MAC CE indicating the PCell change is received. For example, the UE may perform the PCell change operation K1 symbols later, at the nearest slot after K1 symbols, or at the nearest slot-group boundary after K1 symbols from the time when the DCI or MAC CE indicating the PCell change is received. As another example, the UE may perform the PCell change operation K2 msec later, at the nearest symbol after K2 msec, or at the nearest slot-group boundary after K2 msec from the time when the UE transmits HARQ-ACK feedback corresponding to the DCI or MAC CE indicating the PCell change. Here, the certain time for delaying the PCell change operation, such as K1 symbols or K2 msec, may be predefined or configured, or may be configured by a UE capability signaling report. The fixed time can be set in units of symbols, slots, or msec.

[0288] According to an embodiment, a timer value for a PCell change operation may be set and / or defined in advance. The UE may start the timer when the PCell is changed from PCell_old to PCell_new, and when the timer value expires, the UE may change the PCell from PCell_new to PCell_old again.

[0289] [Example #2] Example in which at least some of the functions of the existing PCell are performed by PCell_new when the PCell is changed

[0290] The PCell may be temporarily changed in consideration of the traffic load. That is, since the amount of traffic load may change over time, the PCell may be temporarily changed from PCell_old to PCell_new during a period when the load is low, and then restored to the existing PCell_old. In this case, a lot of higher layer signaling may be required to transfer all the functions of the PCell from PCell_old to PCell_new and then restore it to PCell_old. This may also lead to an increase in latency and require a significant change in the operation of the UE. Therefore, when the PCell is changed according to the above-described embodiment #1, only some of the functions performed or supportable in the existing PCell_old may be performed in the PCell_new. For example, as shown in the following embodiments #2-1 to #2-3, at least some of the functions executable in the PCell_old may be performed in the PCell_new.

[0291] 22 illustrates an example of a procedure for transferring at least a portion of the functionality of a PCell in a wireless communication system according to an embodiment of the present disclosure.

[0292] 22, in step S2201, the UE determines a PCell change from a first cell to a second cell. That is, the UE can determine that the PCell should be changed from the first cell to the second cell by receiving an instruction for PCell change from the base station. The instruction for PCell change can be sent via at least one of the signaling methods described in Example #1.

[0293] In step S2203, the UE checks the PCell capabilities to be transferred to the second cell. That is, the UE can check at least one PCell capability to be performed on the second cell, which is a new PCell (e.g., PCell_new), among the PCell capabilities that were operating on the first cell, which is an existing PCell (e.g., PCell_old), and / or the PCell capabilities configured to operate on the first cell. The PCell capabilities to be transferred to the second cell can be determined based on a preset rule or an instruction from the base station (e.g., an instruction based on higher layer signaling or DCI).

[0294] In step S2205, the UE performs the confirmed PCell functionality in the second cell. That is, the UE can perform the confirmed PCell functionality in the second cell by transferring the confirmed PCell functionality from the first cell to the second cell. At this time, the UE can perform signaling necessary to transfer the confirmed PCell functionality from the first cell to the second cell. Here, the remaining PCell functionality other than the confirmed PCell functionality can continue to be performed in the first cell. That is, the remaining PCell functionality other than at least one PCell functionality transferred to the second cell among the PCell functionality that was operating in the first cell and / or PCell functionality configured to operate in the first cell can be maintained to continue operating in the first cell. Alternatively, according to another embodiment, the remaining PCell functionality other than the confirmed PCell functionality may not be performed in the first cell, and the UE may not transmit or receive signals via the first cell.

[0295] In the embodiment described with reference to FIG. 22, at least one confirmed function is transferred to the second cell, and at least one remaining function is provided in the first cell. In another embodiment, at least one confirmed function is transferred to the second cell, some of the at least one remaining function is provided in the first cell, and at least one remaining function is suspended. By suspending at least one function, energy saving efficiency can be increased. Here, the at least one function to be suspended can be predefined, or configured or indicated by the base station. The at least one function to be suspended can be preconfigured and / or indicated during a carrier aggregation configuration process, or configured and / or indicated together with an instruction for PCell change. For example, in one embodiment, a paging function can be suspended.

[0296] As in the embodiment described with reference to Figure 22, only some functions may be transferred to the PCell_new due to the PCell change. The at least one function to be transferred may be defined in various ways depending on a specific embodiment. In addition, the at least one function to be transferred may be predefined or may be configured or signaled by the base station and thus indicated to the terminal. Specifically, the following functions may be transferred to the PCell_new:

[0297] Example #2-1) PDCCH monitoring function

[0298] All or part of the PDCCH monitoring performed or configured to be performed on PCell_old can be performed on PCell_new. Specifically, PDCCH monitoring functions for a specific type of CSS set, a specific DCI format, and / or a specific SS set index (e.g., SS set index 0) can be controlled to be performed on PCell_new instead of PCell_old. Here, the specific type of CSS set can include at least one of the 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 defined in the TS 38.213 standard. Alternatively, the specific DCI format can include at least one of DCI format 0_0, DCI format 1_0, DCI format 2_X, or DCI format 4_X.

[0299] Of the PDCCH monitoring performed or configured to be performed on the PCell_old, some PDCCH monitoring performed on the PCell_new instead of the PCell_old may be predefined or configured by higher layer signaling. For example, the type of CSS set, DCI format, and SS set index for which PDCCH monitoring is performed on the PCell_new may be predefined or configured by higher layer signaling.

[0300] According to alternative embodiment #2-1-1, when PDCCH monitoring for a specific CSS set is performed in PCell_new, configuration related to PDCCH monitoring for the specific CSS set can be configured for each serving cell. The configuration related to PDCCH monitoring for the specific CSS set may include configuration related to a monitoring pattern for the CSS set, a CORESET index, and / or the number of PDCCH candidates for each aggregation level. Here, the monitoring pattern for the CSS set may include at least one of periodicity, offset, and symbol position of a PDCCH opportunity within a slot.

[0301] According to alternative embodiment #2-1-2, when PDCCH monitoring for a specific CSS set is performed in PCell_new, the settings regarding PDCCH monitoring for the specific CSS set already configured in PCell_old can be inherited directly to PCell_new.

[0302] In the case of alternative embodiment #2-1-2, in order to minimize ambiguity that may occur when applying a monitoring pattern, a constraint that the SCS and / or duplex mode (e.g., FDD or TDD) between PCell_new and PCell_old must be the same may be applied. Alternatively, regardless of the alternative embodiment, a constraint that the SCS and / or duplex mode (e.g., FDD or TDD) between PCell_new and PCell_old must be the same may be applied to a target SCell that is a PCell change. Alternatively, due to SS set index linkage between PCell_new and PCell_old, the PCell function for PDCCH monitoring can be performed on PCell_new. For example, when PCell_new and PCell_old have a predefined or configured linkage relationship, the terminal can perform PDCCH monitoring on PCell_new by replacing at least a portion of the configuration for SS set index m of PCell_new with the configuration for SS set index n of PCell_old. The connection relationship between the SS set index n of PCell_old and the SS set index m of PCell_new may be set in advance or may be automatically set when n=m.

[0303] Example #2-2) Random access procedure related functions

[0304] At least some of the functions related to the random access procedure may be performed in PCell_new. For example, at least some of the HARQ-ACK transmissions corresponding to msg1 / 2 / 3 / 4 and msg4 in the 4-step RACH procedure and msgA / B and msgB in the 2-step RACH procedure may be performed in PCell_new.

[0305] According to alternative embodiment #2-2-1, when PRACH (or msgA) transmission is performed on PCell_new, the configuration of the PRACH (or msgA) transmission resource can be configured for each serving cell. According to alternative embodiment #2-2-2, when PRACH (or msgA) transmission is performed on PCell_new, the configuration of the PRACH (or msgA) transmission resource already configured in PCell_old can be inherited to PCell_new as is.

[0306] Example #2-3) PUCCH transmission function

[0307] At least some of the PUCCH transmissions may be performed on PCell_new. That is, at least some of the transmissions for PUCCHs whose transmission is instructed to be performed periodically and / or semi-statically for transmitting SR and / or CSI, etc., and / or whose transmission is instructed to be performed aperiodically for transmitting HARQ-ACK, etc., may be performed on PCell_new. According to alternative embodiment #2-3-1, when PUCCH transmission is performed on PCell_new, the configuration of the PUCCH transmission resources may be configured for each serving cell. According to alternative embodiment #2-3-2, when PUCCH transmission is performed on PCell_new, the configuration of the PUCCH transmission resources already configured in PCell_old may be inherited to PCell_new.

[0308] Among the functions (or operations) performed in the PCell_old, at least some of the functions performed in the PCell_new can be configured by higher layer signaling. According to one embodiment, some K candidate functions among the functions performed in the PCell_old are configured by higher layer signaling, and at least one operation among the K operations to be performed on the actual PCell_new can be dynamically indicated in the manner proposed in embodiment #1.

[0309] According to one embodiment, the terminal may perform some of the functions of PCell_old on PCell_new only for a certain period of time (e.g., T1 slot or T2 msec) from the time the PCell is changed from PCell_old to PCell_new in accordance with a PCell change instruction, and may perform all of the functions of PCell_old on PCell_new after the certain period of time has elapsed.

[0310] [Example #3] Example of PCell change when SCell operating as PCell_new is in deactivation state or dormant state

[0311] 23 illustrates an example of a procedure for changing a PCell based on the state of a target cell in a wireless communication system according to an embodiment of the present disclosure.

[0312] Referring to FIG. 23, in step S2301, the UE checks the status of a target cell for PCell change. That is, the UE may determine a target cell to operate as a PCell_new from among multiple SCells configured for carrier aggregation, and check the status of the determined target cell. The target cell to operate as a PCell_new may be an SCell instructed to operate as a PCell via DCI or MAC CE, as described in Example #1. Here, the status of the target cell may include a status indicating whether the target cell is activated and / or dominant. For example, if the target cell is a cell operating in BWP, which is an inactive state, or BWP, which is a dormant state, the UE may determine that the status of the target cell is an inactive state.

[0313] In step S2303, the UE determines whether a PCell change to the target cell is possible. If the state of the target cell is in a deactivation state or an active BWP in the target cell is in a dormant state, the UE determines that a PCell change to the target cell is impossible. On the other hand, if the state of the target cell is in an activation state and the active BWP is not in a dormant state, the UE determines that a PCell change to the target cell is possible.

[0314] If PCell change to the target cell is not possible, in step S2305, the UE performs additional operations for PCell change. For example, the UE may perform operations to change the state of the target cell or select a new target cell. To this end, the UE may transmit and / or receive at least one message or signal with the base station. According to one embodiment, the UE may perform BWP switching to a BWP that is not in an idle state among BWPs configured for the target cell. A BWP that is not in an inactive state or an idle state may be configured in advance. According to another embodiment, the UE may select another SCell that is not in an inactive state as the target cell. For example, the UE may select an SCell having a designated serving cell index as the new target cell from among SCells included in the same CG or the same PUCCH group as the PCell. The designated serving cell index may be the lowest serving cell index, the highest serving cell index, or a pre-configured serving cell index.

[0315] In step S2307, the UE performs a PCell change procedure. That is, if an additional operation is performed in step S2305, the UE can change the PCell in the switched BWP or change the PCell to another SCell. Alternatively, if it is determined in step S2303 that a PCell change to the target cell is possible, the UE can change the PCell from the existing PCell_old to the target cell. As a result, the target cell can become the PCell_new of the UE.

[0316] In the description with reference to Figure 23, if PCell change to the target cell is not possible, the UE performs an additional operation for PCell change and then performs a PCell change procedure. However, according to an embodiment of the present disclosure, the UE can maintain the existing PCell_old without performing the PCell change procedure. That is, if the state of the PCell change target cell is an inactive state, the UE can continue to perform the PCell function with the existing PCell_old without changing the PCell.

[0317] 24 illustrates an example of a procedure for preventing deactivation of a PCell change target cell in a wireless communication system according to an embodiment of the present disclosure.

[0318] 24, in step S2401, the UE checks target cell candidates for PCell change. According to an embodiment, the target cell candidates for PCell change may be indicated by the base station via DCI or MAC CE. According to an embodiment, the target cell candidates for PCell change may be determined during the SCell configuration process.

[0319] In step S2403, the UE applies an inactivation prevention configuration for the confirmed target cell candidate. That is, the UE can restrict the confirmed target cell candidate from transitioning to an inactive state. For example, the UE may not run a timer related to SCell inactivation to restrict the target cell candidate from transitioning to an inactive state. The timer related to SCell inactivation can be configured not to be run via a data scheduling DCI of DCI format 2_6 or DCI format 0_1 / 0_2 / 1_1 / 1_2. As another example, the UE may ignore a transition instruction to an inactive state for the target cell candidate to prevent the target cell candidate from transitioning to an inactive state.

[0320] In the description with reference to Figure 24, the terminal restricts the target cell candidate from transitioning to the inactive state, but the present disclosure is not limited thereto. For example, the terminal may restrict the target cell candidate from transitioning to the dormant state. The transition to the dormant state may be restricted by prohibiting the execution of a dormant-related timer or ignoring an instruction to transition to the dormant state.

[0321] 25 illustrates an example of a procedure for changing a PCell in a wireless communication system according to an embodiment of the present disclosure. 25 illustrates an operation method of a terminal.

[0322] 25, in step S2501, a terminal communicates through a first cell which is a PCell and a second cell which is an SCell. That is, the terminal performs a random access procedure with a base station, and can configure a first cell among serving cells of the base station as a PCell and at least one second cell as an SCell. Here, the first cell is a cell in which the random access procedure is performed, and the at least one second cell may be a cell belonging to the same cell group as the first cell, i.e., a main cell group (MCG), or a cell belonging to another cell group, a secondary cell group (SCG). The terminal can communicate through the first cell which is a PCell and the second cell which is an SCell.

[0323] In step S2503, the UE receives an instruction for PCell change to the second cell. That is, the UE may receive information instructing to change the PCell from the first cell to the second cell via DCI or MAC CE. For example, as described in Example #1, the UE may receive the instruction for PCell change via DCI instructing PUCCH cell switching, a PDCCH order, an SPS / CG configuration, or an NES state.

[0324] In step S2505, the UE determines whether the second cell is in an inactive state. That is, the UE can determine whether the second cell, which is a target cell for PCell change, is in an inactive state. If the second cell is in an inactive state, the UE proceeds to the next step S2507. Alternatively, the UE can proceed to the next step S2507 if the BWP used for the SCell in the second cell is a dormant BWP.

[0325] If the second cell is in an inactive state, in step S2507, the UE changes the PCell to the third cell or another BWP of the second cell. That is, if the second cell is in an inactive state, the UE may change the PCell to a third cell that is not in an inactive state. In this case, the third cell may be an SCell with the lowest, highest, or specified serving cell index among SCells in the same CG or the same PUCCH group as the first cell. Alternatively, if an active BWP for the SCell in the second cell is in a dormant state, the UE may change the PCell to the second cell by performing BWP switching to another BWP that is not in a dormant state. Here, the other BWP may be a BWP that is not in a dormant state and may be configured in advance. Then, the UE can perform at least some of the functions of the PCell that are performed or configured to be performed in the first cell in the other BWP of the second cell or the third cell.

[0326] If the second cell is not in an inactive state, in step S2507, the terminal performs a procedure to change the PCell to the second cell. That is, the terminal can change the PCell from the first cell to the second cell. Thereafter, the terminal can perform, on the second cell, at least some of the functions of the PCell that are performed or configured to be performed on the first cell.

[0327] [Example #4] When both the primary DRX group and secondary DRX group of the UE are configured, and the FR (frequency range) 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 belonged to the secondary DRX group before the PCell change, the secondary DRX group configuration may not be applied after the PCell change, and the primary DRX group configuration may be commonly applied to all serving cells. As another example, if PCell_new belonged to the secondary DRX group before the PCell change, primary DRX group configuration parameters may be applied to the serving cell corresponding to the FR to which PCell_new belongs, and secondary DRX group configuration parameters may be applied to the serving cell corresponding to the FR to which PCell_old belongs. This may have the advantage that the configuration for the DRX group to which the PCell belongs remains the same as the configuration for the primary DRX group before and after the PCell change.

[0328] As described above, the present disclosure can achieve energy conservation in a base station by dynamically changing the PCell of a terminal through PCell change instruction signaling and suggesting terminal operations related to PDCCH monitoring, random access procedure, PUCCH transmission, or DRX in response to the PCell change.

[0329] The above-mentioned proposed methods may be implemented independently, or may be implemented in a combined (or merged) form of some of the proposed methods. Rules can be defined so that the base station notifies the terminal of the application information of these proposed methods (or information on the rules of the proposed methods) via a predefined signal (e.g., a physical layer signal or a higher layer signal).

[0330] The present disclosure may be embodied in other specific forms without departing from the technical ideas and essential features described in the present disclosure. Therefore, the above detailed description should not be interpreted as limiting in all respects, but should be considered as illustrative. The scope of the present disclosure should be determined by reasonable interpretation of the appended claims, and all modifications within the scope of equivalence of the present disclosure are included in the scope of the present disclosure. In addition, claims that do not have an explicit reference relationship in the claims may be combined to form embodiments, or new claims may be included by amendment after filing. [Industrial Applicability]

[0331] The embodiments of the present disclosure can be applied to various wireless access systems, such as 3GPP (3rd Generation Partnership Project) and 3GPP2 systems.

[0332] The embodiments of the present disclosure can be applied not only to the various wireless access systems described above, but also to any technical field to which the various wireless access systems are applied. Furthermore, the proposed method can also be applied to mmWave and THz communication systems that use ultra-high frequency bands.

[0333] Furthermore, embodiments of the present disclosure may be applied to a variety of applications, such as free-floating vehicles and drones.

Claims

1. 1. A method of operating a terminal in a wireless communication system, comprising: performing a random access procedure with a base station; setting a first cell among the cells of the base station as a PCell (primary cell); setting a second cell among the cells of the base station as an SCell (secondary cell); receiving an instruction to change the PCell to the second cell; If the second cell is in an inactivation state or an active bandwidth part (BWP) of the terminal in the second cell is 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.

2. 2. The method of claim 1, wherein the instruction to change to the second cell is received based on at least one of downlink control information (DCI) indicating physical uplink control channel (PUCCH) cell switching, a physical downlink control channel (PDCCH) order, a configured scheduling (SPS / CG) configuration of a specific index, or a network energy saving (NSE) state.

3. The method of claim 1 , further comprising transferring at least some functionality of the PCell from the first cell to the second cell.

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

5. The method of claim 3 , wherein the at least some of the capabilities are indicated based on at least one of higher layer signaling or DCI.

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

7. The method of claim 6 , wherein after the PCell is changed, a secondary DRX group configuration is applied to the first cell.

8. Identifying at least one candidate target cell that can be changed to the PCell; The method of claim 1 , further comprising restricting deactivation state transitions for the at least one candidate target cell.

9. 9. The method of claim 8, wherein the restriction on the transition to the deactivation state is based on at least one of prohibiting execution of a timer related to deactivation or ignoring an instruction to transition to the deactivation state for the at least one target cell candidate.

10. The method of claim 1 , wherein the PCell change is performed after a predefined or set time has elapsed since receiving an instruction to change the PCell to the second cell.

11. 2. The method of claim 1, further comprising: after changing the PCell to the second cell or the third cell, changing the PCell to the first cell based on expiration of a timer started by the PCell change.

12. 1. A method of operating a base station in a wireless communication system, comprising: performing a random access procedure with a terminal; Setting a first cell among the cells of the base station as a PCell (primary cell) of the terminal; Setting a second cell among the cells of the base station as an SCell (secondary cell) of the terminal; and sending to the terminal an indication not to change the PCell to the second cell.

13. A terminal in a wireless communication system, A transmitter / receiver, a processor connected to the transceiver; The processor: Perform a random access procedure with the base station, Setting a first cell among the cells of the base station as a PCell (primary cell); Setting a second cell among the cells of the base station as an SCell (secondary cell); receiving an instruction to change the PCell to the second cell; If the second cell is in an inactivation state or the active BWP (bandwidth part) of the terminal in the second cell is dormant, the terminal changes the PCell to a third cell different from the second cell, or controls the terminal to change the PCell to the second cell after switching the active BWP.

14. A base station in a wireless communication system, comprising: A transmitter / receiver, a processor connected to the transceiver; The processor: Perform random access procedures with the terminal, Setting a first cell among the cells of the base station as a PCell (primary cell) of the terminal; Setting a second cell among the cells of the base station as an SCell (secondary cell) of the terminal; A base station that controls to send an instruction to the terminal to change the PCell to the second cell.

15. A communication device, at least one processor; at least one computer memory coupled to the at least one processor and storing instructions that direct operations to be executed by the at least one processor; The operation is performing a random access procedure with a base station; setting a first cell among the cells of the base station as a PCell (primary cell); setting a second cell among the cells of the base station as an SCell (secondary cell); receiving an instruction to change the PCell to the second cell; If the second cell is in an inactivation state or the active bandwidth part (BWP) of the terminal in the second cell is 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 bandwidth part (BWP).

16. A non-transitory computer-readable medium storing at least one instruction, The at least one instruction executable by a processor is included; The at least one command may be used by the device to: The processor: Perform a random access procedure with the base station, Setting a first cell among the cells of the base station as a PCell (primary cell); Setting a second cell among the cells of the base station as an SCell (secondary cell); receiving an instruction to change the PCell to the second cell; If the second cell is in an inactivation state or the active bandwidth part (BWP) of the terminal in the second cell is dormant, the PCell is changed to a third cell different from the second cell, or the active bandwidth part (BWP) is switched and then the PCell is changed to the second cell.

Images