Method and device for early transmission of sounding reference signal in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present disclosure relates to operations of a terminal and a base station in a wireless communication system, and, specifically, the present disclosure relates to a method for transmitting / receiving an uplink reference signal in a wireless communication system, and a device capable of performing same. The present disclosure provides a device and a method capable of effectively providing a service in the wireless communication system.

Description

Method and apparatus for early transmission of a sounding reference signal in a wireless communication system

[0001] The present disclosure relates to the operation of a terminal and a base station in a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for early transmission of a sounding reference signal in a wireless communication system. The present disclosure relates to a method for obtaining early UL / DL MIMO performance gain by rapidly transmitting a sounding reference signal (SRS) during the process of a terminal in inactive mode switching to an RRC connected mode, and an apparatus capable of performing the same.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands called millimeter waves (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz band (e.g., 3 terahertz (3 THz) band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology.

[0003] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), technologies such as beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands, support for various numerologies (such as the operation of multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources, initial access techniques to support multi-beam transmission and broadband, definition and operation of Band-Width Parts (BWP), Low Density Parity Check (LDPC) codes for high-volume data transmission, new channel coding methods such as Polar Codes for the reliable transmission of control information, and L2 pre-processing (L2 Standardization has been carried out for pre-processing, network slicing which provides a dedicated network specialized for specific services, and other methods.

[0004] Currently, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology, taking into account the services that the 5G mobile communication technology was intended to support. Additionally, standardization of the physical layer is in progress for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0005] In addition, standardization is underway in the field of wireless interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes to expand network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step Random Access (2-step RACH for NR) which simplifies random access procedures. Standardization is also underway in the field of system architecture / services for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for the integration of Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0006] When such 5G mobile communication systems are commercialized, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] Furthermore, the advancement of these 5G mobile communication systems encompasses multi-antenna transmission technologies such as new waveforms to guarantee coverage in the terahertz band of 6G mobile communication technology, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas; metamaterial-based lenses and antennas to improve terahertz band signal coverage; high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum); and Reconfigurable Intelligent Surface (RIS) technology; as well as Full Duplex technology for enhancing frequency efficiency and system networks in 6G mobile communication technology; AI-based communication technologies that realize system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions; and the realization of services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could serve as a foundation for the development of next-generation distributed computing technologies.

[0008] As a result of the aforementioned developments and advancements in mobile communication systems, it has become possible to provide a variety of services, and thus measures to effectively provide these services are required.

[0009] The disclosed embodiments aim to provide an apparatus and method capable of effectively providing services in a mobile communication system.

[0010] The present invention, for solving the above-mentioned problems, is characterized in that a method for processing a control signal in a wireless communication system comprises: a step of receiving a first control signal transmitted from a base station; a step of processing the received first control signal; and a step of transmitting a second control signal generated based on the processing to the base station.

[0011] The disclosed embodiments provide an apparatus and method capable of effectively providing services in a mobile communication system.

[0012] FIG. 1 is a diagram illustrating the operation of DRX in a wireless communication system according to one embodiment of the present disclosure.

[0013] FIG. 2 is a diagram illustrating a method for configuring a DCI format 2_7 that can trigger an SRS when the PEI can indicate whether to page four paging occasions according to one embodiment of the present disclosure.

[0014] FIG. 3 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while the base station switches a terminal in an inactive state to a connected state when DL traffic occurs, according to one embodiment of the present disclosure.

[0015] FIG. 4 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while performing a RACH procedure using a PRACH resource that is not dedicated to the terminal, in order for a terminal in an inactive state to transition to a connected state when UL traffic occurs, according to one embodiment of the present disclosure.

[0016] FIG. 5 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while performing a RACH procedure using a PRACH resource dedicated to the terminal, in order for the terminal to transition to a connected state when UL traffic occurs, according to one embodiment of the present disclosure.

[0017] FIG. 6 is a drawing illustrating the structure of a terminal in a wireless communication system according to one embodiment of the present disclosure.

[0018] FIG. 7 is a drawing illustrating the structure of a base station in a wireless communication system according to one embodiment of the present disclosure.

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0020] In describing the embodiments of the present disclosure, descriptions of technical details that are well known in the art to which the present disclosure belongs and are not directly related to the present disclosure are omitted. This is intended to convey the essence of the present disclosure more clearly without obscuring it by omitting unnecessary explanations.

[0021] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the dimensions of each component do not entirely reflect their actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference numbers.

[0022] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided to ensure that the present disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present disclosure, if it is determined that a detailed description of a related function or configuration might unnecessarily obscure the essence of the present disclosure, such detailed description is omitted. Additionally, the terms described below are defined considering their functions in the present disclosure, and these may vary depending on the intentions or conventions of the user or operator. Therefore, their definitions should be based on the content throughout the specification.

[0023] Hereinafter, a base station is an entity that performs resource allocation for terminals and may be at least one of a gNode B, eNode B, Node B, BS (base station), radio access unit, base station controller, or a node on a network. A terminal may include a UE (user equipment), MS (mobile station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. In this disclosure, a downlink (DL) may be a wireless transmission path for a signal transmitted by a base station to a terminal. An uplink (UL) may refer to a wireless transmission path for a signal transmitted by a terminal to a base station. Furthermore, while LTE or LTE-A systems may be described as examples below, embodiments of this disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, 5th generation mobile communication technologies (5G, new radio, NR) developed after LTE-A may be included therein, and the 5G below may be a concept that includes existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without departing significantly from the scope of the present disclosure. Various embodiments of the present disclosure may be applied in FDD (frequency division duplex) or TDD (time division duplex).

[0024] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Computer program instructions may be loaded onto the processor of a general-purpose computer, a specialized computer, or other programmable data processing equipment. The instructions executed through the processor of the computer or other programmable data processing equipment will produce means to perform the functions described in the flow diagram block(s). Computer program instructions may be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the functions in a specific manner. Instructions stored in computer-available or computer-readable memory may produce a manufactured item containing instruction means to perform the functions described in the flow diagram block(s). Computer program instructions may be loaded onto a computer or other programmable data processing equipment. Instructions for performing a series of operation steps on a computer or other programmable data processing equipment to create a process to be executed on the computer or other programmable data processing equipment may provide steps for executing the functions described in the flowchart block(s).

[0025] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). Furthermore, in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For example, two blocks described in succession may actually be executed substantially simultaneously. It is also possible for the blocks to be executed in reverse order according to their corresponding functions.

[0026] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Thus, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Furthermore, in various embodiments of the present disclosure, the 'parts' may include one or more processors. In the following description of the present disclosure, detailed descriptions of related known functions or configurations may be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Various embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0027] Wireless communication systems are evolving from providing early voice-oriented services to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards like 3GPP’s HSPA (high speed packet access), LTE (long term evolution or E-UTRA (evolved universal terrestrial radio access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2’s HRPD (high rate packet data), UMB (ultra mobile broadband), and IEEE’s 802.16e.

[0028] As a representative example of the above-mentioned broadband wireless communication system, the LTE system employs the orthogonal frequency division multiplexing (OFDM) method for the downlink (DL) and the single carrier frequency division multiple access (SC-FDMA) method for the uplink (UL). The uplink refers to a wireless link through which a terminal (UE (user equipment) or MS (mobile station)) transmits data or control signals to a base station (eNode B, or base station (BS)), and the downlink refers to a wireless link through which a base station transmits data or control signals to a terminal. The aforementioned multiple access method can distinguish the data or control information of each user by allocating and operating time-frequency resources to be carried on each user so that they do not overlap, that is, so that orthogonality is established.

[0029] As a future communication system following LTE, 5G communication systems must be able to freely reflect the diverse requirements of users and service providers, and therefore, services that satisfy various requirements simultaneously must be supported. Services being considered for 5G communication systems include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra reliability low latency communication (URLC).

[0030] eMBB aims to provide data transmission speeds that are superior to those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a peak data rate of 20 Gbps in the downlink and 10 Gbps in the uplink from the perspective of a single base station. Furthermore, while providing these peak data rates, the 5G communication system must also provide an increased user-perceived data rate. To satisfy these requirements, it necessitates improvements in various transmission and reception technologies, including enhanced multi-input multi-output (MIMO) transmission technology. Additionally, while LTE transmits signals using a maximum bandwidth of 20 MHz in the 2 GHz band, the 5G communication system can meet the data transmission speeds required by using a frequency bandwidth wider than 20 MHz in frequency bands of 3–6 GHz or above 6 GHz.

[0031] Simultaneously, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide IoT, mMTC requires support for a large number of terminal connections within a cell, improved terminal coverage, enhanced battery life, and reduced terminal costs. Since IoT devices are attached to various sensors and equipment to provide communication functions, the system must be able to support a large number of terminals within a cell (e.g., 1,000,000 terminals / km²). Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in dead zones not covered by cells, such as building basements; therefore, they may require wider coverage compared to other services provided by 5G communication systems. Terminals supporting mMTC must consist of low-cost devices, and since it is difficult to frequently replace terminal batteries, a very long battery life of 10 to 15 years may be required.

[0032] URLLC is a mission-critical cellular-based wireless communication service. Examples include services used for remote control of robots or machinery, industrial automation, unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, the communication provided by URLLC must offer very low latency and very high reliability. For instance, services supporting URLLC must satisfy air interface latency of less than 0.5 milliseconds, and simultaneously 10 -5It has the following packet error rate requirements. Therefore, for services supporting URLLC, 5G systems must provide a transmit time interval (TTI) smaller than other services, and at the same time, design considerations may be required to allocate a wide resource in the frequency band to ensure the reliability of the communication link.

[0033] The three 5G services, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted within a single system. In this case, different transmission and reception techniques and parameters may be used between the services to satisfy the different requirements of each service. Of course, 5G is not limited to the three services mentioned above.

[0034] Hereinafter, a / b may be understood as at least one of a or b. For convenience of explanation, some terms and names defined in 3GPP standards (specifications for 5G, NR, LTE, or similar systems) may be used. However, the present disclosure is not limited by these terms and names and may be equally applied to systems conforming to other standards. Furthermore, terms used in the following description to identify a connection node, to refer to network entities, to refer to messages, to refer to interfaces between network entities, to refer to various identification information, etc., are examples provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms used in it, and other terms referring to objects having equivalent technical meanings may be used.

[0035] [SS / PBCH Block]

[0036] Next, we will explain the SS (synchronization signal) / PBCH (physical broadcast channel) blocks in 5G.

[0037] An SS / PBCH block may refer to a physical layer channel block composed of PSS (primary synchronization signal), SSS (secondary synchronization signal), and PBCH. Specifically, it is as follows.

[0038] - PSS: A signal that serves as the reference for downlink time / frequency synchronization and provides some information about the cell ID.

[0039] - SSS: Serves as the reference for downlink time / frequency synchronization and provides the remaining cell ID information not provided by PSS. Additionally, it can serve as a reference signal for PBCH demodulation.

[0040] - PBCH: Provides essential system information required for transmitting and receiving data channels and control channels of the terminal. The essential system information may include search space-related control information representing wireless resource mapping information of the control channel, scheduling control information for a separate data channel that transmits system information, etc.

[0041] - SS / PBCH block: An SS / PBCH block is composed of a combination of PSS, SSS, and PBCH. One or more SS / PBCH blocks may be transmitted within a time of 5ms, and each transmitted SS / PBCH block may be distinguished by an index.

[0042] The terminal can detect PSS and SSS during the initial connection phase and can decode PBCH. It can obtain a master information block (MIB) from PBCH and receive a control resource set (CORESET) #0 corresponding to the control area with a control area index of 0. The terminal can perform monitoring of control area #0 by assuming that the selected SS / PBCH block and the demodulation reference signal (DMRS) transmitted from control area #0 are quasi-co-located (QCL). The terminal can receive system information using downlink control information transmitted from control area #0. The terminal can obtain configuration information related to the random access channel (RACH) required for initial connection from the received system information. The terminal can transmit a physical RACH (PRACH) to the base station considering the selected SS / PBCH index, and the base station receiving the PRACH can obtain information regarding the SS / PBCH block index selected by the terminal. The base station can know that the terminal has selected a block among the respective SS / PBCH blocks and is monitoring the associated control area #0.

[0043] [DRX]

[0044] FIG. 1 is a diagram illustrating a discontinuous reception (DRX) operation in a wireless communication system according to one embodiment of the present disclosure.

[0045] DRX (discontinuous reception) is an operation in which a terminal using a service receives data discontinuously while in an RRC connected state, where a wireless link is established between the base station and the terminal. When DRX is applied, the terminal can turn on the receiver at specific points to monitor the control channel, and turn off the receiver if no data is received for a certain period to reduce the terminal's power consumption. DRX operation can be controlled by a MAC layer device based on various parameters and timers.

[0046] Referring to FIG. 1, Active time (105) may be the time during which the terminal wakes up at each DRX cycle to monitor the PDCCH. Active time (105) may be defined as follows.

[0047] - drx-onDurationTimer or drx-InactivityTimer or drx-RetransmissionTimerDL or drx-RetransmissionTimerUL or ra-ContentionResolutionTimer is running; or

[0048] - a Scheduling Request is sent on PUCCH and is pending; or

[0049] - a PDCCH indicating a new transmission addressed to the C-RNTI of the MAC entity has not been received after successful reception of a Random Access Response for the Random Access Preamble not selected by the MAC entity among the contention-based Random Access Preamble

[0050] drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, ra-ContentionResolutionTimer, etc. are timers whose values ​​are set by the base station, and may have the function of setting the terminal to monitor the PDCCH when certain conditions are satisfied.

[0051] Drx-onDurationTimer (115) may be a parameter for setting the minimum time the terminal stays awake in a DRX cycle. drx-InactivityTimer (120) may be a parameter for setting the additional time the terminal stays awake when receiving a PDCCH (130) instructing a new uplink transmission or downlink transmission. drx-RetransmissionTimerDL may be a parameter for setting the maximum time the terminal stays awake to receive a downlink retransmission in a downlink HARQ procedure. drx-RetransmissionTimerUL may be a parameter for setting the maximum time the terminal stays awake to receive an uplink retransmission grant in an uplink HARQ procedure. drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, and drx-RetransmissionTimerUL may be set, for example, to time, number of subframes, number of slots, etc. ra-ContentionResolutionTimer can be a parameter for monitoring PDCCH in a random access procedure.

[0052] The inActive time (110) is a time during which the PDCCH is not monitored or / or the PDCCH is not received during the DRX operation. The remaining time after subtracting the Active time (105) from the total time of performing the DRX operation may be the inActive time (110). If the terminal does not monitor the PDCCH during the Active time (105), it may enter a sleep or inActive state to reduce power consumption.

[0053] The DRX cycle can refer to the period during which a terminal wakes up and monitors the PDCCH. The DRX cycle can refer to the time interval or on-duration occurrence cycle between when the terminal monitors a PDCCH and when it monitors the next PDCCH. There are two types of DRX cycles: short DRX cycle and long DRX cycle. The short DRX cycle can be applied optionally.

[0054] Long DRX cycle (125) may be the longer of the two DRX cycles set in the terminal. While operating with Long DRX, the terminal restarts Drx-onDurationTimer (115) at a point where Long DRX cycle (125) has elapsed from the starting point (e.g., start symbol) of Drx-onDurationTimer (115). When operating with Long DRX cycle (125), the terminal may start Drx-onDurationTimer (115) in a slot after drx-SlotOffset in a subframe satisfying [Equation 1] below. Here, drx-SlotOffset refers to the delay before starting Drx-onDurationTimer (115). For example, drx-SlotOffset can be set to time, the number of slots, etc.

[0055]

[0056] At this time, drx-LongCycleStartOffset can be used to define the subframe to start the Long DRX cycle (125) and drx-StartOffset can be used to define the subframe to start the Long DRX cycle (125). For example, drx-LongCycleStartOffset can be set to a time, the number of subframes, the number of slots, etc.

[0057] [Regarding SRS]

[0058] Next, a method for estimating an uplink channel using the transmission of a terminal's SRS (sounding reference signal) is described. A base station may set at least one SRS configuration for each uplink BWP to transmit configuration information for SRS transmission to the terminal. A base station may set at least one SRS resource set for each SRS configuration. According to one embodiment, the base station and the terminal may exchange upper-level signaling information as follows to transmit information regarding the SRS resource set.

[0059] - srs-ResourceSetId: SRS resource set index

[0060] - srs-ResourceIdList: A set of SRS resource indices referenced by the SRS resource set

[0061] - resourceType: A time-axis transmission setting for the SRS resource referenced in the SRS resource set, which can be set to at least one of 'periodic', 'semi-persistent', or 'aperiodic'. If set to 'periodic' or 'semi-persistent', associated CSI-RS information may be provided depending on the use case of the SRS resource set. If set to 'aperiodic', a non-periodic SRS resource trigger list and slot offset information may be provided, and associated CSI-RS information may be provided depending on the use case of the SRS resource set.

[0062] - usage: A setting for the usage of an SRS resource referenced in an SRS resource set, which can be set to at least one of 'beamManagement', 'codebook', 'nonCodebook', or 'antennaSwitching'.

[0063] - alpha, p0, pathlossReferenceRS, srs-PowerControlAdjustmentStates: Provides parameter settings for controlling the transmit power of the SRS resource referenced in the SRS resource set.

[0064] The terminal can understand that the SRS resources included in the set of SRS resource indices referenced in the SRS resource set follow the information set in the SRS resource set.

[0065] Additionally, the base station and the terminal may transmit and receive upper-layer signaling information to transmit individual configuration information for an SRS resource. According to one embodiment, the individual configuration information for an SRS resource may include time-frequency axis mapping information within the slot of the SRS resource. The individual configuration information for an SRS resource may include information regarding frequency hopping within or between slots of the SRS resource. Additionally, the individual configuration information for an SRS resource may include a time-axis transmission setting of the SRS resource and may be set to at least one of 'periodic', 'semi-persistent', and 'aperiodic'. This may be limited to having the same time-axis transmission setting as the SRS resource set containing the SRS resource. If the time-axis transmission setting of the SRS resource is set to 'periodic' or 'semi-persistent', the SRS resource transmission period and slot offset (e.g., periodicityAndOffset) may additionally be included in the time-axis transmission setting.

[0066] A base station can enable, deactivate, or trigger SRS transmission to a terminal via upper-layer signaling, including RRC signaling or MAC CE signaling, or L1 signaling (e.g., DCI). For example, a base station can enable or deactivate periodic SRS transmission to a terminal via upper-layer signaling. A base station can instruct an SRS resource set with resourceType set to periodic to be enabled via upper-layer signaling, and the terminal can transmit an SRS resource referenced in the enabled SRS resource set. The time-frequency axis resource mapping within the slot of the transmitted SRS resource follows the resource mapping information set in the SRS resource, and the slot mapping, including the transmission period and slot offset, may follow the periodicityAndOffset set in the SRS resource. A spatial domain transmission filter applied to the transmitted SRS resource may refer to spatial relation info set in the SRS resource. A spatial domain transmission filter applied to the transmitted SRS resource may refer to associated CSI-RS information set in the SRS resource set containing the SRS resource. The terminal can transmit an SRS resource within an active uplink BWP for a periodic SRS resource activated through upper layer signaling.

[0067] For example, a base station can enable or disable semi-persistent SRS transmission to a terminal via upper-layer signaling. The base station can instruct the terminal to enable an SRS resource set via MAC CE signaling. The terminal can transmit an SRS resource referenced in the enabled SRS resource set. The SRS resource set enabled via MAC CE signaling may be limited to an SRS resource set where resourceType is set to semi-persistent. The time-frequency axis resource mapping within the slot of the transmitted SRS resource follows the resource mapping information set in the SRS resource, and the slot mapping, including the transmission period and slot offset, may follow the periodicityAndOffset set in the SRS resource. Additionally, the spatial domain transmission filter applied to the transmitted SRS resource may refer to spatial relation info set in the SRS resource or associated CSI-RS information set in the SRS resource set containing the SRS resource. If spatial relation info is configured in an SRS resource, a spatial domain transmission filter can be determined by referring to the configuration information regarding the spatial relation info transmitted via MAC CE signaling that enables semi-persistent SRS transmission without adhering to it. The terminal can transmit the SRS resource within the uplink BWP enabled for the semi-persistent SRS resource activated via upper layer signaling.

[0068] For example, a base station can trigger an aperiodic SRS transmission to a terminal via the DCI. The base station can indicate one of the aperiodic SRS resource triggers (aperiodicSRS-ResourceTrigger) through the SRS request field of the DCI. The terminal can understand that among the configuration information of the SRS resource set, an SRS resource set containing the aperiodic SRS resource trigger indicated via the DCI from the list of aperiodic SRS resource triggers has been triggered. The terminal can transmit the SRS resource referenced in the triggered SRS resource set. The time-frequency axis resource mapping within the slot of the transmitted SRS resource may follow the resource mapping information set in the SRS resource. Additionally, the slot mapping of the transmitted SRS resource may be determined through the slot offset between the PDCCH containing the DCI and the SRS resource, which may reference at least one value included in the set of slot offsets set in the SRS resource set. Specifically, the slot offset between the PDCCH containing the DCI and the SRS resource may be the value indicated in the time domain resource assignment field of the DCI among at least one offset value included in the set of slot offsets set in the SRS resource set. The spatial domain transmission filter applied to the transmitting SRS resource may refer to the spatial relation info set in the SRS resource. The spatial domain transmission filter applied to the transmitting SRS resource may refer to the associated CSI-RS information set in the SRS resource set containing the SRS resource.The terminal can transmit an SRS resource within an uplink BWP that is enabled for a non-periodic SRS resource triggered via DCI.

[0069] When a base station triggers aperiodic SRS transmission to a terminal via DCI, a minimum time interval may be required between the PDCCH containing the DCI triggering the aperiodic SRS transmission and the transmitted SRS so that the terminal can apply configuration information for the SRS resource and transmit the SRS. The time interval for the terminal's SRS transmission may be defined as the number of symbols between the last symbol of the PDCCH containing the DCI triggering the aperiodic SRS transmission and the first symbol mapped to the first transmitted SRS resource among at least one transmitted SRS resource. The minimum time interval may be determined by referencing the PUSCH preparation procedure time required for the terminal to prepare for PUSCH transmission. Additionally, the minimum time interval may have different values ​​depending on the usage of the SRS resource set containing the transmitted SRS resource. For example, the minimum time interval may be determined by N2 symbols defined by considering the terminal's processing capability according to the terminal's capability, referencing the terminal's PUSCH preparation procedure time. Additionally, considering the usage of the SRS resource set including the transmitted SRS resource, if the usage of the SRS resource set is set to 'codebook' or 'antennaSwitching', the minimum time interval can be set to N2 symbols. Considering the usage of the SRS resource set including the transmitted SRS resource, if the usage of the SRS resource set is set to 'nonCodebook' or 'beamManagement', the minimum time interval can be set to N2+14 symbols.The terminal transmits an aperiodic SRS when the time interval for the aperiodic SRS transmission is greater than or equal to the minimum time interval, and can ignore the DCI that triggers the aperiodic SRS when the time interval for the aperiodic SRS transmission is less than the minimum time interval.

[0070]

[0071] The spatialRelationInfo setting information in [Table 1] above may be applied to the beam used for SRS transmission by referencing a single reference signal and the beam information of the reference signal. For example, the spatialRelationInfo setting may include information such as that in [Table 2] below.

[0072]

[0073] Referring to the spatialRelationInfo setting above, the index of the reference signal to be referenced in order to use the beam information of a specific reference signal—namely, the SS / PBCH block index, CSI-RS index, or SRS index—can be set. The upper signaling referenceSignal is configuration information indicating which reference signal's beam information to reference for the corresponding SRS transmission, and ssb-Index can mean the SS / PBCH block index, csi-RS-Index the CSI-RS index, and srs the SRS index, respectively. If the value of the upper signaling referenceSignal is set to 'ssb-Index', the terminal can apply the receiving beam used when receiving the SS / PBCH block corresponding to ssb-Index as the transmitting beam for the corresponding SRS transmission. If the value of the upper signaling referenceSignal is set to 'csi-RS-Index', the terminal can apply the receiving beam used when receiving the CSI-RS corresponding to csi-RS-Index as the transmitting beam for the corresponding SRS transmission. When the value of the upper signaling referenceSignal is set to 'srs', the terminal can apply the transmission beam used during the transmission of the SRS corresponding to srs as the transmission beam for the transmission of the SRS.

[0074] The contents of this disclosure are applicable to FDD and TDD systems. Hereinafter, upper signaling (or upper layer signaling) in this disclosure is a signal transmission method transmitted from a base station to a terminal using a physical layer downlink data channel, or from a terminal to a base station using a physical layer uplink data channel, and may be referred to as RRC signaling, PDCP signaling, or a MAC (medium access control) control element (MAC CE).

[0075] In the present disclosure, when determining whether cooperative communication is applied, the terminal may use various methods, such as the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied having a specific format, or the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied including a specific indicator indicating whether cooperative communication is applied, or the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied being scrambled with a specific RNTI, or assuming the application of cooperative communication in a specific section indicated to an upper layer. For convenience of explanation, the case in which the terminal receives a PDSCH to which cooperative communication is applied based on conditions similar to those above will be referred to as the NC-JT case.

[0076] In the following disclosure, determining the priority between A and B may be referred to in various ways, such as selecting the one with the higher priority according to a predetermined priority rule and performing the corresponding action, or omitting or dropping the action for the one with the lower priority.

[0077] In the following disclosure, the examples are described through a number of embodiments, but these are not independent, and one or more embodiments may be applied simultaneously or in combination.

[0078] For convenience in the following description of the present disclosure, cells, transmission points, panels, beams, and / or transmission directions that can be distinguished through upper layer / L1 parameters such as TCI state or spatial relation information, or indicators such as cell ID, TRP ID, and panel ID, may be described uniformly as TRP (transmission reception point), beam, or TCI state. Therefore, in actual application, TRP, beam, or TCI state can be appropriately replaced with one of the above terms.

[0079] In the present disclosure, when determining whether cooperative communication is applied, the terminal may use various methods, such as the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied having a specific format, or the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied including a specific indicator indicating whether cooperative communication is applied, or the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied being scrambled with a specific RNTI, or assuming the application of cooperative communication in a specific section indicated to an upper layer. For convenience of explanation thereafter, the case in which the terminal receives a PDSCH to which cooperative communication is applied based on conditions similar to those above will be referred to as the NC-JT case.

[0080] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Hereinafter, a base station is an entity that performs resource allocation for terminals and may be at least one of a gNode B, gNB, eNode B, Node B, BS (Base Station), wireless access unit, base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. Although embodiments of the present disclosure are described below using a 5G system as an example, embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel types. For example, LTE or LTE-A mobile communication and mobile communication technologies developed after 5G may be included therein. Accordingly, embodiments of the present disclosure may be applied to other communication systems with some modifications without significantly departing from the scope of the present disclosure, as judged by a person skilled in the art. The content of the present disclosure is applicable to FDD and TDD systems.

[0081] Furthermore, in describing the present disclosure, if it is determined that a detailed description of related functions or configurations could unnecessarily obscure the essence of the present disclosure, such detailed description is omitted. Additionally, the terms described below are defined in consideration of their functions within the present disclosure, and these definitions may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0082] In describing the present disclosure below, the term "upper layer signaling" may refer to a signaling corresponding to at least one or a combination of at least one of the following signalings.

[0083] - MIB (Master Information Block)

[0084] - SIB (System Information Block) or SIB

[0085] - RRC (Radio Resource Control)

[0086] - MAC (Medium Access Control) CE (Control Element)

[0087] In addition, L1 signaling may be a signaling corresponding to at least one or a combination of at least one of the following physical layer channels or signaling methods using signaling.

[0088] - PDCCH (Physical Downlink Control Channel)

[0089] - DCI (Downlink Control Information)

[0090] - Terminal-specific (UE-specific) DCI

[0091] - Group common DCI

[0092] - Common DCI

[0093] - Scheduling DCI (e.g., DCI used for the purpose of scheduling downlink or uplink data)

[0094] - Non-scheduling DCI (e.g., DCI not intended for scheduling downlink or uplink data)

[0095] - PUCCH (Physical Uplink Control Channel)

[0096] - UCI (Uplink Control Information)

[0097] The term "slot" used in the present disclosure below is a general term that may refer to a specific time unit corresponding to TTI (Transmit Time Interval), and specifically, it may refer to a slot used in a 5G NR system, or a slot or subframe used in a 4G LTE system.

[0098] In the following disclosure, the examples are described through a number of embodiments, but these are not independent, and one or more embodiments may be applied simultaneously or in combination.

[0099] The terminal can use energy saving technology to conserve the terminal's energy. As described above, the terminal can switch to an RRC-INACTIVE state (hereinafter 'inactive state') through DRX operation, and at the physical layer, the terminal can reduce power consumption by turning off the receiver if there is no signaling from the base station to switch to an RRC-CONNECTED state (hereinafter 'connected state') after monitoring the control channel at a specific time.

[0100] If DL (downlink) traffic is generated to be transmitted to a terminal in an inactive state, the base station may signal to switch the terminal from an inactive state to a connected state, and the terminal may initiate a procedure to switch from an inactive state to a connected state through periodic monitoring.

[0101] If the base station has DL traffic to transmit to a terminal in an inactive state, the base station may transmit a DCI for paging purposes to the terminal to resume the terminal to a connected state. After receiving a Paging Occasion (PO) that identifies the terminal's UE ID, the terminal may perform a RACH procedure. Through the RACH procedure, the terminal transmits PRACH and receives a Random Access Response (RAR) to obtain a value for Timing Adjustment (TA), after which it transmits PUSCH (Msg3) to the base station. Finally, the base station transmits Msg4 to the terminal to inform it of the contention resolution for the terminal that has transitioned to a connected state, thereby resuming the terminal to a connected state. Subsequently, if necessary, the base station may update RRC parameters by reconfiguring some RRCs. After the base station and the terminal transmit and receive DL / UL channels and the base station has transmitted all DL traffic to the terminal, if no additional traffic (DL or UL) occurs, the terminal can switch back to the inactive state or enter the idle state (RRC_IDLE state).

[0102] If a terminal in an inactive state has UL traffic to transmit to a base station, the terminal may perform a RACH procedure to resume to a connected state. Similar to the above, the terminal performs a RACH procedure to receive TA information, adjusts the TA, and finally resumes to a connected state after contention resolution. Likewise, the base station resets some RRCs if necessary, and the terminal may transmit UL traffic to the base station via CG (configured grant) based UL transmission (i.e., CG type 1 PUSCH) according to the RRC parameters set (or reset) by the base station, or transmit UL traffic to the base station via CG type 2 PUSCH or DG (dynamic grant) based PUSCH according to the DCI information transmitted by the base station to the terminal.

[0103] In the process of resuming the terminal by switching it to a connected state when UL or DL ​​traffic occurs on a terminal in an inactive state, it can be assumed that the terminal monitors the SSB to achieve synchronization in the time domain.

[0104] The sounding reference signal (SRS) is used by a base station to measure the UL channel to support uplink precoding (UL precoding). To schedule the SRS for UL precoding to a terminal, the base station may set RRC parameters so that the usage of the SRS triggers an SRS resource set configured as codebook or non-Codebook, or transmits it periodically (periodically or semi-persistently). Alternatively, the SRS may be used in a TDD system to support downlink precoding (DL precoding) by the base station measuring the UL channel with the SRS and estimating the DL channel using channel reciprocity. In this case, to schedule the SRS for DL ​​precoding to a terminal, the base station may set RRC parameters so that the usage of the SRS triggers an SRS resource set configured as antennaSwitching, or transmits it periodically (periodically or semi-persistently). At this time, the terminal must be configured so that the antenna port used to transmit the SRS (hereinafter SRS AS) for antenna switching purposes and the antenna port used to receive the DL channel transmitted by the base station are the same.

[0105] The RRC parameters for the aforementioned SRS are set in the SRS-Config, and since the SRS-Config is set within the terminal-specific (UE dedicated or UE specific) BWP-UplinkDedicated, the terminal can transmit the SRS after receiving the UE dedicated RRC parameters following the transition to the connected state. The terminal cannot transmit the SRS during the initial access (IA) process, such as the RACH procedure, and before receiving the UE dedicated RRC parameters following the transition to the connected state.

[0106] As such, SRS can only be used after the terminal has transitioned to a connected state and received UE-dedicated RRC parameters. There can be a significant delay in the base station receiving the SRS and estimating the UL channel after the terminal receives the DCI (if it is aperiodic SRS) to trigger the SRS and transmits the SRS. If the terminal transitions from an inactive state to a connected state, there is no need to receive UE-dedicated RRC parameters (unless the RRC parameters are reset), so no time is required to receive the RRC parameters. However, the time required for the process of the terminal transitioning from an inactive state to a connected state, the time required for the base station to receive the SRS after the terminal transmits it, and the time required for the base station to use the received SRS (which may include the time required to estimate the channel with the SRS and calculate the precoder) can be very large. Consequently, a long delay may occur when the base station performs UL precoding or DL ​​precoding using the SRS.

[0107] As described above, since SRS is transmitted according to UE-dedicated RRC parameter settings, the terminal may be unable to transmit SRS while transitioning to a connected state and while receiving RRC resets. Furthermore, because the base station and the terminal cannot perform DL precoding and UL precoding, high-efficiency transmission techniques based on MIMO cannot be utilized. Consequently, performance in terms of the overall system (especially data throughput) is significantly reduced compared to when using MIMO-based precoding techniques. SRS transmission and reception delays can cause problems not only with data throughput loss resulting from the inability to use DL / UL precoding but also with supporting multi-user (MU) support. If the base station can receive SRS from terminals, the base station's central processing unit (e.g., DU (distributed unit or digital unit) or CU (control unit or central unit)) can determine which terminals to support simultaneously (UE pairing or MU pairing) using the same time and frequency resources based on the UL channel estimated from the SRS transmitted by each terminal. However, if a delay occurs at the time of transmitting and receiving SRS, a delay may occur in the base station performing UE pairing using the UL channels of the terminals estimated by the SRS. If, due to such a delay in the base station performing UE pairing, only a single terminal is supported by the time and frequency resources, the spectral efficiency (SE) for those resources may decrease. Similarly, since the spectral efficiency for those time and frequency resources decreases, the overall system throughput may be degraded.

[0108] In this way, if the terminal can trigger an SRS and transmit it while the terminal transitions from an inactive state to a connected state due to the occurrence of data traffic for the purpose of energy saving, it will be possible to resolve the performance degradation of the overall system throughput that may occur due to the delay in SRS transmission and reception as described above.

[0109] In the first embodiment among the various embodiments of the present disclosure, a method for setting RRC parameters to transmit SRS in an inactive state is specifically described. In particular, a new SRS setting method for efficiently operating SRS in an inactive state is proposed.

[0110] In the second embodiment among the various embodiments of the present disclosure, when DL traffic to be transmitted to a terminal in an inactive state occurs, a method is described to trigger the terminal, which is transitioning from an inactive state to a connected state, to transmit the SRS early, and for the terminal to transmit it.

[0111] In the third embodiment among the various embodiments of the present disclosure, when UL traffic to be transmitted to a base station occurs for a terminal in an inactive state, a method is described to trigger the terminal transitioning from an inactive state to a connected state to transmit the SRS early, and for the terminal to transmit it.

[0112] [First Embodiment: RRC configuration method for transmitting SRS in an inactive state]

[0113] In the first embodiment, if the terminal can transmit SRS in an inactive state, a method for setting RRC parameters for the base station to transmit SRS in an inactive state is described.

[0114] If a terminal is triggered to transmit an SRS during the transition from an inactive state to a connected state, and the base station receives the transmitted SRS to support DL / UL MIMO-based transmission and reception techniques, the overall system throughput performance can be improved because SRS-based DL / UL MIMO transmission and reception techniques can be supported without delay or with minimal delay. To support this technique, the terminal must have the capability to transmit an SRS while transitioning from an inactive state to a connected state, and the base station can set RRC parameters on the terminal to support this. Furthermore, the base station must store RRC settings (i.e., context information) for the terminal in the inactive state, and based on the stored context, it can clearly understand the terminal's behavior in the inactive state and its behavior in the connected state. If the base station with which the terminal intends to communicate does not store the terminal's context information, the base station can clearly understand the terminal's behavior after receiving context information from another base station that does store the terminal's context information.

[0115] The base station may set RRC parameters for SRS that the terminal can transmit in the inactive state in SuspendConfig. The base station may set new RRC parameters (e.g., srs-RRC-Inactive or srs-RRC-InactiveEnhanced) on the terminal to support a method of transmitting SRS in the inactive state. The base station may set the following parameters in the new RRC parameters to support the method of transmitting SRS in the inactive state (hereinafter referred to as the early SRS transmission method):

[0116] - SRS resources

[0117] - BWP where SRS is transmitted

[0118] - UL band (NUL or SUL) containing the BWP through which SRS is transmitted

[0119] - Cell ID (CellIdentity) to indicate a valid zone where SRS can be transmitted

[0120] The SRS configured within the above-described SuspendConfig can be defined as an SRS for UL / DL transmission and reception rather than an SRS for positioning purposes. Specifically, the base station may configure RRC parameters to support an early SRS transmission method in the terminal by considering some or a combination of various methods for configuring RRC parameters to set SRS resources as follows.

[0121] - In a TDD system, considering UL and DL transmissions, two SRS resource sets with different usages can be configured to support the early SRS transmission method. For example, a base station can configure an SRS resource set with usage 'codebook' and an SRS resource set with usage 'antennaSwitching' for a terminal. Alternatively, the base station can configure an SRS resource set with usage 'nonCodebook' and an SRS resource set with usage 'antennaSwitching' for the terminal. That is, the base station can configure either an SRS resource set with usage 'codebook' or an SRS resource set with usage 'nonCodebook' for the terminal, and in addition, configure an SRS resource set with usage 'antennaSwitching'. The two SRS resource sets configured in this way may have the following characteristics.

[0122] -- The base station may set RRC parameters so that the same SRS resource is included in the two SRS resource sets configured on the terminal. Some SRS resource(s) within the two SRS resource sets configured on the terminal by the base station may be identical. Alternatively, all SRS resource(s) within the two SRS resource sets configured on the terminal by the base station may be identical.

[0123] -- The base station can set the aperiodicSRS-ResourceTrigger (or aperiodicSRS-ResourceTriggerList) for two SRS resource sets to the same value so that two SRS resource sets configured in the terminal can be triggered with the same trigger state of the same DCI.

[0124] -- The base station can set the slotOffset for two SRS resource sets to the same value so that the two SRS resource sets configured in the terminal can be transmitted to the same time resource.

[0125] -- The base station can set availableSlotOffsetList to the same value so that the terminal can transmit two SRS resource sets configured in the terminal by checking availability up to the same time resource.

[0126] -- The base station may set alpha and / or p0 and / or pathlossReferenceRS and / or srs-PowerControlAdjustmentStates and / or pathlossReferenceRSList and / or followUnifiedTCI-STateSRS and / or applyIndicatedTCI-State to the same value so that the terminal can transmit two SRS resource sets configured in the terminal with the same transmission power.

[0127] - In a TDD system, an SRS resource set capable of supporting multiple usages can be configured by considering UL transmission and DL transmission. For example, a base station can set the usage of the SRS resource set for early SRS transmission configured in SuspendConfig to either 'codebook-antennaSwitching' or 'nonCodebook-antennaSwitching'. Alternatively, the base station can set usage1 and usage2 in the SRS resource set for early SRS transmission configured in SuspendConfig to indicate both usages. In this case, the base station can set usage1 and usage2 to 'codebook' and 'antennaSwitching', respectively, or set usage1 and usage2 to 'nonCodebook' and 'antennaSwitching', respectively.

[0128] - In the TDD system, considering UL transmission and DL transmission, the base station sets the usage of the SRS resource set for early SRS transmission configured in SuspendConfig to 'antennaSwitching'. However, through the conditions described below, the base station and the terminal can establish a rule so that the antenna port transmitting PUSCH and the antenna port configured to transmit the SRS resource for antennaSwitching match, so that some of the SRS resources transmitted for 'antennaSwitching' can be used to calculate the precoders of codebook PUSCH or non-codebook PUSCH.

[0129] Among the multiple SRS resources configured in the SRS resource set for 'antenna switching', it is assumed that the base station and the terminal use the same terminal antenna port and PUSCH antenna port to transmit the first SRS resource (the SRS-Resource with the smallest SRS-ResourceId value).

[0130] Among the multiple SRS resources configured in the SRS resource set for 'antenna switching', it is assumed that the terminal antenna port used to transmit the last SRS resource (the SRS-Resource with the largest SRS-ResourceId value) and the PUSCH antenna port are the same for the base station and the terminal.

[0131] Among the multiple SRS resources configured in the 'antenna switching' SRS resource set, any antenna port used to transmit an SRS resource may also be used as an antenna port for transmitting a PUSCH, and the base station may indicate a single SRS resource using the SRS resource indicator (SRI) within the DCI for scheduling the PUSCH. In this case, it is assumed that the terminal antenna port used to transmit the indicated SRS resource and the terminal antenna port to be used to transmit the PUSCH scheduled by the base station are configured identically.

[0132] - If the base station sets the usage of the SRS resource set for early SRS transmission configured in SuspendConfig to 'nonCodebook' through some or a combination of the methods described above, the following additional settings and actions are required.

[0133] -- The base station may additionally configure a CSI-RS resource that can be associated with an SRS resource set for 'nonCodebook' use in the terminal. Similar to the SRS resource set, NZP-CSI-RS-Resource may be configured within SuspendConfig, and the base station may additionally configure an NZP-CSI-RS-ResourceId associated within the RRC parameter for the SRS resource set for 'nonCodebook' use in the terminal.

[0134] -- If an SRS resource set for 'non-Codebook' is associated with NZP-CSI-RS-Resource, the base station must transmit NZP-CSI-RS-Resource to the terminal before the terminal transmits the SRS resource set for 'non-Codebook'. That is, the terminal must be able to receive NZP-CSI-RS-Resource while transitioning from an inactive state to a connected state, and the base station must set RRC parameters for this in the terminal.

[0135] If the terminal has mobility, it can perform a procedure to transition from an inactive state to a connected state at a base station different from the base station it was connected to while in a connected state. As described above, base stations within a certain range store the context for the terminal (i.e., the terminal's RRC parameter information configured when in a connected state), and the terminal can determine the SRS resource set to transmit to the base station performing the procedure to transition from an inactive state to a connected state. At this time, the base station can set the RRC parameters for multiple cells as shown in the following table to enable the transmission of SRS to one (or more) of the multiple cells in the SuspendConfig of the terminal that transitioned from a connected state to an inactive state. Table 3 below shows an example of the settings for RRC parameters for early SRS transmission configured in the SuspendConfig set by the base station for the terminal. The terminal can identify the SRS resource set settings for the corresponding cell through the base station's Cell ID (CellIdentity) that can be identified while performing the procedure to transition from an inactive state to a connected state, and use this to transmit SRS to the corresponding base station. The number of cells adjacent to the terminal can be defined as a maximum maxNrOfCellsInVA, and SRS can be transmitted for a number of cells less than or equal to a maximum maxNrOfCellsInVA (e.g., 16).

[0136]

[0137]

[0138] [Second Embodiment: Method for triggering and transmitting early SRS when DL traffic occurs]

[0139] In the second embodiment, when DL traffic to be transmitted to a terminal in an inactive state occurs at a base station, a method for triggering an early SRS while the base station transitions the inactive terminal to a connected state and a method for the terminal to transmit the triggered SRS to the base station early are described.

[0140] If a base station has DL traffic to transmit to a terminal in an inactive state, the base station can page the terminal to transition it to a connected state. The terminal monitors the paging occasion (PO) for the relevant base station to receive a PDCCH for paging purposes and a PDSCH scheduled to that PDCCH to identify the RACH occasion (RO) on which the terminal will perform the RACH procedure. Subsequently, the terminal can transition to a connected state according to the RACH procedure, and after the RRC setup is complete, the terminal can receive DL traffic from the base station.

[0141] Since the terminal cannot determine whether the base station is performing paging on the terminal due to the occurrence of DL traffic to be transmitted to the terminal, the terminal can check whether the base station is paging the terminal by monitoring the PO configured by the base station. In this case, since the terminal must periodically monitor the PO, the energy saving (ES) effect may be reduced. To compensate for this, a new DCI format 2_7 may be introduced for the purpose of providing a new paging early indication (PEI). The terminal receives the DCI format 2_7 for PEI (hereinafter PEI) and can identify the bits for indicating whether paging is required for the terminal by referring to the terminal ID and RRC parameter settings. More specifically, the terminal can identify the subgroup to which it belongs based on the terminal ID (UE ID) and / or RRC parameters. The subgroup may include multiple terminals. Furthermore, the PEI may indicate one of the subgroups to monitor each PO for multiple POs. If PEI sets the bit corresponding to the subgroup containing the terminal among the bits corresponding to the subgroup of a PO to 1, the terminal can monitor the PO. If PEI sets the bit corresponding to the subgroup containing the terminal to 1 for multiple POs, the terminal may need to monitor all multiple POs for which the bit corresponding to the subgroup containing the terminal is set to 1. In this case, the terminal monitors the multiple POs that PEI instructs to monitor, and can monitor the multiple POs sequentially in the time domain.If a terminal monitors multiple POs sequentially, and receives a PDCCH for the terminal from a particular PO (i.e., the terminal successfully receives the PDCCH via P-RNTI), the terminal does not monitor the subsequent PO(s) following the PO that received the PDCCH among the multiple POs to be monitored for its subgroup. In other words, the terminal can identify a single PO among the multiple POs that can be indicated by PEI that is capable of receiving the PDCCH for paging the terminal. Alternatively, the base station may utilize multiple POs to page a single terminal, judging that the terminal may fail to receive the PDCCH from a particular PO; similarly, if the terminal successfully receives the PDCCH from a particular PO, it may no longer monitor subsequent POs.

[0142] The base station may trigger an SRS to enable the terminal to transmit an SRS while transitioning the terminal from an inactive state to a connected state. The base station may trigger an SRS at the following times to trigger an SRS for a terminal transitioning from an inactive state to a connected state.

[0143] [Trigger Method 1]

[0144] According to one embodiment, a base station may add an SRS request field corresponding to a bit of each paging indication field to DCI format 2_7 for indicating PEI. A terminal may transmit an SRS according to the SRS request field corresponding to the bit indicating the PO that detected its own PDCCH among the bits of the paging indication field. If the base station and the terminal support DCI format 2_7 for PEI (hereinafter PEI), SRS request fields may be added to DCI format 2_7. The number of SRS request fields may be defined as the number of paging occasions that can be indicated by PEI. For example, if the number of paging occasions indicated by DCI format 2_7 is 4 (this is just an example and can be set to one of 1, 2, 4, or 8 via the RRC parameter po-NumPerPEI) and the number of subgroups of paging occasions is 8 (this is just an example and can be set to one of 1 to 8 via the RRC parameter subgroupsNumPerPO (or subgroupsNumForUEID)), the number of bits in the paging indication field can be defined as 32. In this case, 4 SRS request fields may be added to DCI format 2_7, and each SRS request field may be used to trigger an SRS for a terminal detecting a PDCCH for paging for each paging occasion. Specifically, the first SRS request field can be used to trigger the SRS of a terminal that has successfully received a PDCCH for paging purposes (PDCCH detected by P-RNTI) through the first paging occasion that can direct monitoring via PEI.Similarly, the fourth SRS request field can be used to trigger the SRS of a terminal that has successfully received a paging PDCCH via the fourth paging occasion, which can be directed to monitor via PEI. If no terminal has successfully received a paging PDCCH via PEI for a specific paging occasion (e.g., the second paging occasion), the SRS request field associated with that paging occasion (e.g., the second SRS request field) may be ignored. The number of bits in the SRS request field associated with each paging occasion can be defined as 1 bit. If the 1 bit of any SRS request field is 0, the base station does not trigger the SRS for a terminal receiving a paging PDCCH via the paging occasion associated with that SRS request field. If 1 bit of any SRS request field is 1, the base station triggers one SRS resource set set as an RRC parameter or multiple SRS resource sets with the same trigger state set to transmit an SRS (meaning an SRS not for positioning purposes as described in the first embodiment) in the inactive state within the SuspendConfig of a terminal receiving a PDCCH for paging purposes through a paging occasion associated with the said SRS request field. If multiple SRS resource sets within the SuspendConfig are set to transmit an SRS in the inactive state as described in the first embodiment, and the multiple SRS resource sets are set to different trigger states, the number of bits in the SRS request field can be determined as 'ceil(log2(number of different trigger states + 1)).Here, ceil means that if the number inside ceil is not an integer, it is rounded up to an integer. As a specific example, if the number of different trigger states set in multiple SRS resource sets within a SuspendConfig that can be configured on a terminal is 3, the number of bits in the SRS request field can be determined as ceil (log2(3+1)) = 2 bits. The number of bits in each SRS request field associated with each paging occasion can all be the same.

[0145] Alternatively, the number of SRS request fields added to DCI format 2_7 may be defined by the number of bits in the paging indication field that can be indicated by PEI, and each SRS request field may be mapped to a bit of each paging indication field. Each SRS request may be used to trigger the SRS of a terminal that has successfully detected a PDCCH for paging according to the bit of each paging indication field. According to the example described above, if the number of bits in the paging indication field is 32, 32 SRS request fields may be added to DCI format 2_7. And, for example, the first SRS request field may be used to trigger the SRS of a terminal that has successfully received a PDCCH for paging by the first bit of the paging indication field. If no terminal has successfully received a PDCCH for paging by the first bit of the paging indication field, the corresponding SRS request field may be ignored. As previously explained, the number of bits in the SRS request field can be determined based on the number of trigger states in the SRS resource set configured to transmit SRS in the inactive state within the terminal's SuspendConfig.

[0146] FIG. 2 is a diagram illustrating a method for configuring a DCI format 2_7 that can trigger an SRS when the PEI can indicate whether to page four paging occasions according to one embodiment of the present disclosure.

[0147] According to one embodiment, with reference to FIG. 2, the number of paging occasions indicated by PEI in DCI format 2_7, po-NumPerPEI, is set to 'po2', and the paging indication field (201) can indicate a subgroup of terminals monitoring two paging occasions (202, 203). With reference to FIG. 2, the number of terminal subgroups in DCI format 2_7 may be 4. Therefore, the number of bits in the paging indication field (201) may be defined as 2*4 = 8 bits. The paging indication field may consist of the first four bits to indicate one subgroup to monitor the first paging occasion (202) among four terminal subgroups (204, 205, 206, 207), and the subsequent four bits to indicate one subgroup to monitor the second paging occasion (203) among four terminal subgroups (204, 205, 206, 207). For example, if the four bits for indicating the subgroup to monitor the first paging occasion (202) are indicated as '1000', terminals included in the first subgroup (204) of the four subgroups can monitor the first paging occasion (202) to receive the PDCCH for paging. For example, if the four bits for indicating the subgroup to monitor the second paging occasion (203) are indicated as '0010', terminals included in the third subgroup (206) of the four subgroups can monitor the second paging occasion (203) to receive the PDCCH for paging.For example, if both 8 bits for the two paging occasions are indicated as '10001000', terminals included in the first subgroup (204) can monitor the first paging occasion (202) and the second paging occasion (203) to receive the PDCCH for paging. For example, terminals included in the subgroup that are not instructed to monitor the paging occasions can go back to sleep for energy saving. A TRS availability indication field (208) may be added, and detailed operation may follow technical specification TS 38.212. The first example in FIG. 2 may show a case where an SRS request field (209, 210) is set for each paging occasion. In the second example of FIG. 2, the SRS request field (211, 212, 213, 214, 215, 216, 217, 218) may be set for every bit of the paging indication field. In the first example of FIG. 2, the first SRS request field (209) may be used to trigger an SRS for a terminal paging to the first paging occasion (202). In the first example of FIG. 2, the second SRS request field (210) may be used to trigger an SRS for a terminal paging to the second paging occasion (203). In the second example of FIG. 2, the first SRS request field (211) may be used to trigger an SRS for a terminal paging to the first bit of the paging indication field (201).In the second example of FIG. 2, the second SRS request field (212) may be used to trigger an SRS for a terminal that can be paged to the second bit of the paging indication field (201). In the second example of FIG. 2, the third SRS request field (213) through the eighth SRS request field (218) may each be used to trigger an SRS for a terminal that can be paged to the second through eighth bits of the paging indication field (201). The DCI format of FIG. 2 may be DCI format 2_7, enhanced DCI format 2_7, or a new DCI format.

[0148] [Trigger Method 2]

[0149] According to one embodiment, a base station may transmit a PDCCH for paging the terminal to the terminal in DCI format 1_0 scrambled with P-RNTI on a paging occasion set for paging the terminal. The terminal may monitor a set number of paging occasions to receive a PDCCH for paging purposes. The terminal may receive a PDCCH for paging the terminal on one of the paging occasions. Depending on the base station implementation, the base station may transmit a PDCCH for paging the terminal on a number of paging occasions, but if the terminal receives one PDCCH for paging the terminal, it may no longer monitor other paging occasions thereafter. The base station may add an SRS request field to the DCI format 1_0 transmitted as a PDCCH for paging the terminal. The terminal identifies that it is a PDCCH for paging of the terminal and checks the field of DCI format 1_0 transmitted to the PDCCH to determine whether to transmit SRS in an inactive state through the SRS request field included in the same DCI. As described in [Trigger Method 1] above, the number of bits in the SRS request field can be determined according to the number of different trigger states set in multiple SRS resource sets within SuspendConfig to transmit SRS in an inactive state.

[0150] [Trigger Method 3]

[0151] According to one embodiment, for a terminal performing a RACH procedure after paging, the base station may add an SRS request field to the PDCCH for the base station to transmit Msg2 or Msg4 to the terminal during the RACH procedure to trigger an SRS. If a 2-step RACH procedure is supported, the base station may add an SRS request field to the PDCCH for the base station to transmit MsgB to the terminal during the RACH procedure to trigger an SRS. The terminal can determine whether to transmit an SRS in an inactive state by checking the PDCCH for receiving Msg2, Msg4, or MsgB during the RACH procedure through the SRS request field. As described in [Trigger Method 1] above, the number of bits in the SRS request field may be determined according to the number of different trigger states set in a plurality of SRS resource sets within SuspendConfig to transmit an SRS in an inactive state.

[0152] [Trigger Method 4]

[0153] According to one embodiment, the base station and the terminal can set RRC parameters in SuspendConfig to receive DCI format 2_3 in an inactive state, and the terminal can receive DCI format 2_3 and check whether an SRS trigger is present through the SRS request within DCI format 2_3. In addition to RRC parameters for indicating the starting bit that the terminal must interpret within DCI format 2_3 in SuspendConfig, information for receiving DCI format 2_3 can also be set as RRC parameters. The number of bits in the SRS request field included in DCI format 2_3 received in an inactive state may be 2 bits. As described in [Trigger Method 1] above, the number of bits in the SRS request field may be determined according to the number of different trigger states set in a plurality of SRS resource sets in SuspendConfig to transmit SRS in an inactive state.

[0154] [Trigger Method 5]

[0155] According to one embodiment, a new DCI format may be introduced and scrambled with a new RNTI to trigger an SRS in an inactive state. A base station may scramble the new DCI format with a new RNTI and transmit it to a terminal capable of transmitting an SRS in an inactive state. The terminal may receive a PDCCH containing the new DCI format at some point while transitioning from an inactive state to a connected state. The terminal may receive the new DCI format by descrambling it with a new RNTI. The new DCI format may include an SRS request field. As described in [Trigger Method 1] above, the number of bits in the SRS request field may be determined according to the number of different trigger states set in a plurality of SRS resource sets within SuspendConfig to transmit an SRS in an inactive state.

[0156] [Trigger Method 6]

[0157] According to one embodiment, if a terminal receives DCI format 2_7 from a base station to indicate PEI, checks whether PO monitoring is performed for the subgroup to which the terminal belongs within the PEI DCI field, performs PO monitoring according to the DCI instructing to perform monitoring, and succeeds in receiving a PDCCH for paging of the terminal, the terminal can trigger and transmit an SRS resource set configured in SuspendConfig to transmit SRS in an inactive state, even if no separate SRS trigger is instructed by the base station. If the terminal does not support PEI, as described in [Trigger Method 2], if the terminal monitors all paging occasions and succeeds in receiving a PDCCH for paging the terminal (the terminal no longer monitors paging occasions after successfully receiving the PDCCH during monitoring), the terminal can trigger and transmit an SRS resource set configured in SuspendConfig to transmit SRS in an inactive state, even if no separate SRS trigger is instructed by the base station. If a terminal receives a PDCCH for paging purposes and a PDSCH scheduled by the PDCCH and performs a RACH procedure, the terminal can trigger and transmit an SRS resource set configured in SuspendConfig to transmit SRS in an inactive state even if no separate SRS trigger is instructed by the base station after receiving Msg2, Msg4, or MsgB.

[0158] Furthermore, according to one embodiment of the present disclosure, it is obvious to those skilled in the art that some or all of the aforementioned trigger methods may be combined. That is, some of the steps of each trigger method may be combined to perform a new trigger method.

[0159] According to one embodiment, the terminal may be triggered to transmit an SRS according to one or a combination of the various trigger methods described above.

[0160] According to one embodiment, the terminal may check the following conditions before transmitting a triggered SRS. If some or all of the following conditions are satisfied, the terminal transitioning from an inactive state to a connected state may transmit the SRS.

[0161] [Verification Condition 1]

[0162] According to one embodiment, the terminal can verify whether the timing advance (TA) is valid. In order for the terminal to perform UL transmission, it may need to adjust the timing advance by considering the timing difference between the base station and the terminal. The TA between the base station and the terminal is adjusted before the terminal transitions to an inactive state, and even after the terminal transitions to an inactive state, if the terminal's mobility is very low or the amount of channel change is small, the change in the TA may remain small or similar. If there is a large difference in timing between the base station and the terminal, a problem may arise where the reception performance of the UL signal is reduced because interference occurs when receiving the UL signal from the base station and transmitting the DL signal, or because the UL signal cannot be received with the same UL frame as other terminals. Therefore, a terminal transmitting an SRS in an inactive state can verify whether the TA is valid before transmitting the SRS. The terminal in an inactive state can verify the validity of the TA as follows.

[0163] - The terminal can receive a setting from the base station for transmitting SRS in RRC_INACTIVE, and the terminal can store the current RSRP value of the DL (downlink) pathloss reference as the RSRP of the DL pathloss reference.

[0164] - If the terminal receives a TAC (timing advance command) MAC CE or receives a TAC or absolute TAC through a successfully completed RACH procedure, the terminal may update the RSRP of the stored DL pathloss reference to the current RSRP value of the DL pathloss reference. In this case, the DL pathloss reference RSRP updated by the terminal may be defined as the stored RSRP value.

[0165] - When a terminal in an inactive state checks the validity of a TA before transmitting an SRS, the terminal compares the DL pathloss reference RSRP value stored by the terminal with the current RSRP value of the DL pathloss reference. If the value has not increased or decreased significantly above the threshold value set by the RRC parameter (e.g., inactiveSRS-RSRP-ChangeThreshold), and a timer (e.g., inactiveSRS-TimeAlignmentTimer) indicating the validity of a TA is running, the terminal determines that the TA for transmitting the SRS is still valid and can transmit the SRS through the physical layer.

[0166] [Verification Condition 2] According to one embodiment, if a terminal verifies TA validity according to [Verification Condition 1] but determines that the TA is not valid, the terminal may transmit an SRS while performing the RACH procedure. Specifically, a terminal transitioning from an inactive state to a connected state may receive Msg2 from a base station to receive TA information, and then transmit an SRS after adjusting the TA according to the received TA information. A terminal transitioning from an inactive state to a connected state may receive TA information via Msg2 and verify contention resolution via Msg4, and then transmit an SRS through the adjusted TA. If the terminal supports two-step RACH, a terminal transitioning from an inactive state to a connected state may transmit an SRS through the adjusted TA after receiving MsgB.

[0167] Furthermore, according to one embodiment of the present disclosure, it is obvious to those skilled in the art that some or all of the aforementioned verification conditions may be combined. That is, some of the verification conditions may be combined to verify a new verification condition.

[0168] FIG. 3 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while the base station switches a terminal in an inactive state to a connected state when DL traffic occurs, according to one embodiment of the present disclosure.

[0169] According to one embodiment, referring to 301 in FIG. 3, a base station may receive UE capability from a terminal. The base station may receive UE capability from the terminal indicating that it can support early SRS. According to one embodiment, referring to 302 in FIG. 3, the base station may set RRC parameters. The base station may also set RRC parameters for transmitting an early SRS while the terminal transitions from an inactive state to a connected state. According to one embodiment, referring to 303 in FIG. 3, if there is no traffic to transmit or receive to the terminal, the base station may release the terminal to transition it to an inactive state. According to one embodiment, referring to 304 in FIG. 3, DL traffic may occur at the base station to be transmitted to the terminal in an inactive state. According to one embodiment, referring to 305 in FIG. 3, the base station may initiate an RRC resume procedure including paging and RACH procedures to transition the inactive terminal to a connected state to transmit DL traffic. According to one embodiment, referring to 306 in FIG. 3, a base station may trigger an SRS so that a terminal can transmit an SRS early before the RRC resume is completed by using one or a combination of the various trigger methods described above. According to one embodiment, referring to 307 in FIG. 3, a base station may receive the SRS transmitted early by the terminal. According to one embodiment, referring to 308 in FIG. 3, a base station may complete the terminal's RRC resume and transmit DL traffic to be transmitted to the terminal based on the SRS received early and RRC configuration information.

[0170] According to one embodiment, referring to 311 in FIG. 3, the terminal can transmit UE capability to the base station. The terminal can transmit UE capability indicating that it can support early SRS. According to one embodiment, referring to 312 in FIG. 3, the terminal can receive RRC parameters from the base station. The terminal can receive RRC parameters for transmitting early SRS from the base station while transitioning from an inactive state to a connected state. According to one embodiment, referring to 313 in FIG. 3, the terminal can receive a request from the base station to transition from a connected state to an inactive state and transition to an inactive state. The terminal can leave specific RRC parameters (e.g., suspendConfig) in place to perform a specific action (e.g., transmitting early SRS) while in the inactive state. According to one embodiment, referring to 314 in FIG. 3, the terminal can monitor to periodically receive PO or PEI from the base station. The terminal can receive paging messages transmitted by the base station. According to one embodiment, referring to 315 in FIG. 3, while the terminal receives a paging message via PO or PEI, or while receiving a paging message and performing a RACH procedure, the terminal may receive an early SRS trigger from the base station that schedules the early transmission of an SRS from an inactive state. According to one embodiment, referring to 316 in FIG. 3, the terminal may check the validity of a TA. According to one embodiment, referring to 317 in FIG. 3, the terminal may transmit an SRS early depending on whether the TA is valid. According to one embodiment, referring to 318 in FIG. 3, the terminal may complete an RRC resume procedure and transition to a connected state. The terminal may receive DL traffic based on RRC configuration information.

[0171] [Third Embodiment: Method for triggering and transmitting an early SRS when UL traffic occurs]

[0172] In the third embodiment, when UL traffic to be transmitted from a terminal in an inactive state to a base station is generated, a method is described for the terminal to trigger an early SRS while performing a RACH procedure to transition from an inactive state to a connected state, and for the terminal to transmit the triggered SRS to the base station early.

[0173] If UL traffic occurs at a terminal that cannot be processed by small data transmission (SDT), or if UL traffic cannot be processed by SDT because the base station or the terminal does not support SDT, the terminal can perform a RACH procedure to switch to a connected state and transmit the UL traffic to the base station.

[0174] When a terminal in an inactive state transmits a PRACH to a base station to transition to a connected state, the timing at which the terminal can transmit an SRS may vary depending on whether the PRACH resource is operated exclusively for the terminal (UE dedicated PRACH) or whether contention resolution is required because multiple terminals can use the same PRACH resource.

[0175] If the PRACH resource is not exclusive to the terminal, the base station may trigger an SRS on the terminal using various options. As described in the second embodiment, the base station may trigger an SRS on the terminal by considering the following options.

[0176] - Option 1) The base station may add an SRS request field to the PDCCH for transmitting Msg2 to the terminal to trigger SRS. As described above in the second embodiment, the number of bits in the SRS request field may be determined according to the number of different trigger states set in a plurality of SRS resource sets within SuspendConfig to transmit SRS in an inactive state.

[0177] - Option 2) The base station may add an SRS request field to the PDCCH for transmitting Msg4 to the terminal to trigger SRS. As described above in the second embodiment, the number of bits in the SRS request field may be determined according to the number of different trigger states set in a plurality of SRS resource sets within SuspendConfig to transmit SRS in an inactive state.

[0178] - Option 3) If the base station and the terminal support a 2-step RACH procedure, the base station may add an SRS request field to the PDCCH for transmitting the MsbB to the terminal to trigger the SRS. As described above in the second embodiment, the number of bits in the SRS request field may be determined according to the number of different trigger states set in the multiple SRS resource sets within the SuspendConfig to transmit the SRS in an inactive state.

[0179] However, if a RACH procedure is performed using a PRACH resource that is not dedicated to the terminal, the terminal must ultimately receive a Msg4 for contention resolution to resolve the ambiguity as to whether the RACH procedure is intended to transition the terminal to a connected state or to another terminal transitioning to a connected state or making an initial access (IA) at the same time using the same PRACH resource. After confirming through the contention resolution received via the Msg4 that the terminal transitioning to a connected state via the RACH procedure is the terminal in question, the terminal can transmit an SRS to the base station. If terminals attempting an RRC connection resume (transitioning from an inactive state to a connected state) and terminals attempting an initial access transmit an SRS without verifying the contention resolution, severe performance degradation due to interference may occur as the base station may receive an SRS transmitted by a terminal other than the one intending to transition to a connected state.

[0180] FIG. 4 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while performing a RACH procedure using a PRACH resource that is not dedicated to the terminal, in order for a terminal in an inactive state to transition to a connected state when UL traffic occurs, according to one embodiment of the present disclosure.

[0181] According to one embodiment, referring to 401 in FIG. 4, the base station may receive UE capability from the terminal. The base station may receive UE capability from the terminal indicating that it can support early SRS. According to one embodiment, referring to 402 in FIG. 4, the base station may allow the terminal to set RRC parameters. The base station may also set RRC parameters to transmit an early SRS while the terminal transitions from an inactive state to a connected state. According to one embodiment, referring to 403 in FIG. 4, the base station may release the terminal to transition it to an inactive state if there is no traffic to transmit or receive to the terminal. According to one embodiment, referring to 404 in FIG. 4, the base station may receive a PRACH that is not dedicated to the terminal or receive a MsgA from the terminal. According to one embodiment, referring to 405 in FIG. 4, the base station may transmit a RAR to transition the terminal from an inactive state to a connected state. The base station may transmit a MsgB to transition the terminal from an inactive state to a connected state. The base station may trigger an SRS so that the terminal can transmit an SRS early. According to one embodiment, referring to 406 in FIG. 4, the base station may receive Msg3 from the terminal. The base station may transmit Msg4 to the terminal for contention resolution regarding Msg3. If a 2-step RACH procedure is supported, step 406 in FIG. 4 may be omitted. If the base station did not trigger an SRS when transmitting RAR or MsgB, the base station may trigger an SRS when transmitting Msg4 so that the terminal can transmit an SRS early. According to one embodiment, referring to 407 in FIG. 4, the base station may receive an SRS early from the terminal.According to one embodiment, with reference to 408 in FIG. 4, the base station can receive UL traffic by completing the RRC resume of the terminal and scheduling UL transmission to the terminal based on the SRS and RRC configuration information received early.

[0182] According to one embodiment, referring to 411 in FIG. 4, the terminal can transmit UE capability to the base station. The terminal can transmit UE capability to the base station indicating that it can support early SRS. According to one embodiment, referring to 412 in FIG. 4, the terminal can receive RRC parameters from the base station. The terminal can receive RRC parameters for transmitting early SRS from the base station while transitioning from an inactive state to a connected state. According to one embodiment, referring to 413 in FIG. 4, the terminal can receive a request from the base station to transition from a connected state to an inactive state and transition to an inactive state. The terminal can leave specific RRC parameters (e.g., suspendConfig) in place to perform a specific action (e.g., transmitting early SRS) while in the inactive state. According to one embodiment, referring to 414 in FIG. 4, if UL traffic to be transmitted to the base station occurs for the terminal, the terminal can transmit PRACH or MsgA to the base station. According to one embodiment, referring to 415 in FIG. 4, the terminal may receive a RAR from a base station. The terminal may receive a MsgB from the base station. The terminal may receive an early SRS trigger that schedules the early transmission of an SRS along with the RAR or MsgB transmitted by the base station. According to one embodiment, referring to 416 in FIG. 4, the terminal may transmit Msg3 to the base station. The terminal may receive Msg4 from the base station. If a 2-step RACH procedure is supported, step 416 in FIG. 4 may be omitted. If the terminal did not receive an SRS trigger when receiving the RSR or MsgB, the terminal may receive an early SRS trigger that schedules the early transmission of an SRS when receiving Msg4 from the base station.According to one embodiment, referring to 417 in FIG. 4, the terminal can verify the validity of the TA. According to one embodiment, referring to 418 in FIG. 4, the terminal can transmit the SRS early depending on whether the TA is valid. According to one embodiment, referring to 419 in FIG. 4, the terminal can complete the RRC resume procedure and transition to a connected state. The terminal can transmit UL traffic to the base station based on RRC configuration information and the base station's UL channel scheduling information.

[0183] If a terminal according to one embodiment performs a RACH procedure through a terminal-dedicated PRACH resource, the base station and the terminal can know that the RACH procedure is being performed by the terminal even without a contention resolution process. Therefore, the terminal can transmit an SRS to the base station before receiving Msg4. That is, the terminal can receive a RAR containing an SRS trigger for SRS scheduling from the base station and transmit an SRS to the base station (depending on the conditions). At this time, the terminal can check the validity of the TA and, if the TA is valid, transmit the SRS, and if it is not valid, decode the TA information received via the RAR, apply it, and then transmit the SRS to the base station.

[0184] FIG. 5 is a diagram illustrating the operation of a base station and a terminal to trigger early transmission of an SRS while performing a RACH procedure using a PRACH resource dedicated to the terminal, in order for the terminal to transition to a connected state when UL traffic occurs, according to one embodiment of the present disclosure.

[0185] According to one embodiment, referring to 501 in FIG. 5, the base station may receive UE capability from the terminal. The base station may receive UE capability from the terminal indicating that it can support early SRS. According to one embodiment, referring to 502 in FIG. 5, the base station may set RRC parameters. At this time, the base station may also set RRC parameters for transmitting an early SRS while the terminal transitions from an inactive state to a connected state. According to one embodiment, referring to 503 in FIG. 5, the base station may release the terminal to transition it to an inactive state if there is no traffic to transmit or receive to the terminal. According to one embodiment, referring to 504 in FIG. 5, the base station may receive a PRACH from the terminal that is not dedicated to the terminal. The base station may receive a MsgA from the terminal. According to one embodiment, referring to 505 in FIG. 5, the base station may transmit a RAR to transition the terminal from an inactive state to a connected state. The base station may transmit MsgB to transition the terminal from an inactive state to a connected state. The base station may trigger an SRS so that the terminal can transmit an SRS early. According to one embodiment, referring to 506 in FIG. 5, the base station may receive an SRS early from the terminal. According to one embodiment, referring to 507 in FIG. 5, the base station may receive Msg3 from the terminal. The base station may transmit Msg4 to the terminal. If a 2-step RACH procedure is supported, step 507 in FIG. 5 may be omitted. If the terminal has not transmitted an SRS after receiving a RAR or MsgB, the base station may receive an SRS early from the terminal after transmitting Msg4.According to one embodiment, with reference to 508 in FIG. 5, the base station can receive UL traffic by completing the RRC resume of the terminal and scheduling UL transmission to the terminal based on the SRS and RRC configuration information received early.

[0186] According to one embodiment, referring to 511 in FIG. 5, the terminal may transmit UE capability to the base station. The terminal may transmit UE capability indicating that it can support early SRS. According to one embodiment, referring to 512 in FIG. 5, the terminal may receive RRC parameters from the base station. The terminal may receive RRC parameters for transmitting early SRS from the base station while transitioning from an inactive state to a connected state. According to one embodiment, referring to 513 in FIG. 5, the terminal may receive a request from the base station to transition from a connected state to an inactive state and transition to an inactive state. The terminal may leave specific RRC parameters (e.g., suspendConfig) in place to perform a specific action (e.g., transmitting early SRS) while in the inactive state. According to one embodiment, referring to 514 in FIG. 5, if UL traffic to be transmitted to the base station occurs to the terminal, the terminal may transmit PRACH or MsgA to the base station. According to one embodiment, referring to 515 in FIG. 5, the terminal may receive a RAR from the base station. The terminal may receive a MsgB from the base station. The terminal may receive an early SRS trigger that schedules the early transmission of an SRS along with the RAR or MsgB transmitted by the base station. According to one embodiment, referring to 516 in FIG. 5, the terminal may check the validity of a TA. According to one embodiment, referring to 517 in FIG. 5, the terminal may transmit an SRS early depending on whether the TA is valid. According to one embodiment, referring to 518 in FIG. 5, the terminal may transmit a Msg3 to the base station. The terminal may receive a Msg4 from the base station. If a 2-step RACH procedure is supported, step 518 in FIG. 5 may be omitted.If the terminal has not transmitted an SRS after receiving a RAR or MsgB, the terminal may transmit an SRS early after receiving a Msg4. According to one embodiment, with reference to 519 in FIG. 5, the terminal can complete the RRC resume procedure to transition to a connected state and transmit UL traffic to the base station based on RRC configuration information and the base station's UL channel scheduling information.

[0187] In addition, according to one embodiment of the present disclosure, it is obvious to those skilled in the art that some or all of the above-described embodiments may be combined. For example, a new embodiment may be performed by combining the first embodiment and the second embodiment, and a new embodiment may be performed by combining some of the first embodiment and the third embodiment. The combination of embodiments is not limited to the examples described above.

[0188] FIG. 6 is a drawing illustrating the structure of a terminal in a wireless communication system according to one embodiment of the present disclosure.

[0189] According to one embodiment, with reference to FIG. 6, the terminal may include a transceiver (referring to a terminal receiver (600) and a terminal transmitter (610)), a memory (not shown), and a terminal processing unit (605, or a terminal control unit or processor). Depending on the communication method of the terminal described above, the transceiver (600, 610), memory, and terminal processing unit (605) of the terminal may operate. However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more components or fewer components than the components described above. Furthermore, the transceiver, memory, and processor may be implemented in the form of a single chip.

[0190] According to one embodiment, the transceiver can transmit and receive signals with a base station. Here, the signal may include control information and data. To this end, the transceiver may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, the components of the transceiver are not limited to an RF transmitter and an RF receiver.

[0191] According to one embodiment, the transceiver receives a signal through a wireless channel and outputs it to a processor, and can transmit the signal output from the processor through the wireless channel.

[0192] According to one embodiment, the memory may store programs and data necessary for the operation of the terminal. Additionally, the memory may store control information or data included in signals transmitted and received by the terminal. The memory may be composed of a storage medium or a combination of storage media, such as ROM, RAM, a hard disk, CD-ROM, and DVD. Additionally, there may be multiple memories.

[0193] According to one embodiment, a processor can control a series of processes to enable the terminal to operate. For example, the processor can receive a DCI composed of two layers and control the components of the terminal to receive multiple PDSCHs simultaneously. There may be multiple processors, and the processors can perform the operation of controlling the components of the terminal by executing a program stored in memory.

[0194] FIG. 7 is a drawing illustrating the structure of a base station in a wireless communication system according to one embodiment of the present disclosure.

[0195] According to one embodiment, with reference to FIG. 7, a base station may include a transceiver unit (referring to a base station receiver unit (700) and a base station transmitter unit (710)), a memory (not shown), and a base station processing unit (705, or a base station control unit or processor). Depending on the communication method of the base station described above, the transceiver unit (700, 710), the memory, and the base station processing unit (705) of the base station may operate. However, the components of the base station are not limited to the examples described above. For example, the base station may include more components or fewer components than the components described above. In addition, the transceiver unit, the memory, and the processor may be implemented in the form of a single chip.

[0196] According to one embodiment, the transceiver can transmit and receive signals with a terminal. Here, the signal may include control information and data. To this end, the transceiver may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, the components of the transceiver are not limited to an RF transmitter and an RF receiver.

[0197] According to one embodiment, the transceiver receives a signal through a wireless channel and outputs it to a processor, and can transmit the signal output from the processor through the wireless channel.

[0198] According to one embodiment, the memory can store programs and data necessary for the operation of a base station. Additionally, the memory can store control information or data included in signals transmitted and received by the base station. The memory may be composed of a storage medium or a combination of storage media, such as ROM, RAM, a hard disk, a CD-ROM, and a DVD. Additionally, there may be multiple memories.

[0199] According to one embodiment, a processor can control a series of processes to enable a base station to operate. For example, the processor can control each component of the base station to configure two layers of DCIs containing allocation information for a plurality of PDSCHs and to transmit them. There may be multiple processors, and the processors can perform control operations on the components of the base station by executing a program stored in memory.

[0200] Methods according to the claims or embodiments described in the specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0201] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the claims or embodiments described in the specification of this disclosure.

[0202] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0203] Additionally, the program may be stored on an attachable storage device accessible via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0204] In the specific embodiments of the present disclosure described above, the components included in the invention are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0205] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are merely specific examples provided to facilitate the explanation of the technical content of the present disclosure and to aid in understanding the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other variations based on the technical concept of the present disclosure are possible. Furthermore, each of the above embodiments may be combined and operated as needed. For example, a base station and a terminal may be operated by combining parts of one embodiment of the present disclosure with parts of another embodiment. For example, a base station and a terminal may be operated by combining parts of the first embodiment and the second embodiment of the present disclosure. In addition, although the above embodiments are presented based on an FDD LTE system, other variations based on the technical concept of the above embodiments may be implemented in other systems such as TDD LTE systems, 5G, or NR systems.

[0206] Meanwhile, the order of description in the drawings illustrating the method of the present invention does not necessarily correspond to the order of execution, and the order of execution may be changed or executed in parallel.

[0207] Alternatively, drawings describing the method of the present invention may omit some components and include only some components to the extent that the essence of the present invention is not impaired.

[0208] In addition, the method of the present invention may be implemented by combining some or all of the contents included in each embodiment within a scope that does not impair the essence of the invention.

[0209] Various embodiments of the present disclosure have been described above. The foregoing description of the present disclosure is for illustrative purposes only and is not limited to the embodiments disclosed. Those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present disclosure. The scope of the present disclosure is defined by the claims set forth below rather than by the foregoing detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included within the scope of the present disclosure.

Claims

1. Regarding the method performed by the UE (user equipment), A step of receiving configuration information for transmitting an early SRS (sounding reference signal) from a base station; Step of transitioning from a connected state to an inactive state; A step of identifying an early SRS trigger based on DCI (downlink control information) received in the above inactive state; and A method comprising the step of transmitting an SRS to the base station in the inactive state as the early SRS trigger is identified.

2. In Paragraph 1, A method comprising at least one of the above-mentioned configuration information, at least one of an SRS resource set, a BWP (bandwidth part) where the SRS is transmitted, an UL (uplink) band containing the BWP where the SRS is transmitted, or cell ID information for indicating a valid area where the SRS can be transmitted.

3. In Paragraph 2, A method in which at least one SRS resource set of the SRS transmitted in the inactive state is configured to support at least one usage among codebook, non-codebook, codebook and antenna-switching, or non-codebook and antenna-switching.

4. In Paragraph 1, The step of identifying an early SRS trigger based on the DCI received in the above inactive state is: A method comprising the step of identifying an SRS request field included in a PEI (paging early indication).

5. In Paragraph 1, The step of identifying an early SRS trigger based on the DCI received in the above inactive state is: A method comprising the step of identifying an SRS request field in DCI format 1_0 transmitted to a PDCCH (physical downlink control channel) for paging.

6. In Paragraph 1, The step of identifying an early SRS trigger based on the DCI received in the above inactive state is: A method comprising the step of identifying an SRS request field in a PDCCH for transmitting at least one of Msg 2, Msg 4, or Msg B during a RACH (random access channel) procedure.

7. In Paragraph 1, The step of identifying an early SRS trigger based on the DCI received in the above inactive state is: A method comprising the step of identifying an SRS request field in DCI format 2_3 received in the above inactive state.

8. In Paragraph 1, The above method is, The method further includes the step of transmitting at least one of PRACH (physical random access channel) or Msg A to the base station during the RACH procedure in the inactive state as UL traffic to be transmitted to the base station is generated. The step of identifying an early SRS trigger based on the DCI received in the above inactive state is: A method comprising the step of identifying the early SRS trigger based on the DCI containing at least one of scheduling information among Msg B or Msg 2 received from the base station.

9. In Paragraph 1, The step of transmitting SRS to the base station in the above inactive state is, A method comprising the step of transmitting an SRS to a base station when a TA (timing advance) received from the base station is valid.

10. Regarding UE (user equipment): At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the UE: Receive configuration information for transmitting an early SRS (sounding reference signal) from a base station, and Switch from connected state to inactive state, and Identify an early SRS trigger based on DCI (downlink control information) received in the above inactive state, and A UE that transmits an SRS to the base station in the inactive state as the above early SRS trigger is identified.

11. In Paragraph 10, A UE comprising at least one of the above configuration information, which includes at least one SRS resource set, a BWP (bandwidth part) where the SRS is transmitted, an UL (uplink) band containing the BWP where the SRS is transmitted, or cell ID information for indicating a valid area where the SRS can be transmitted.

12. In Paragraph 11, A UE in which at least one SRS resource set of the SRS transmitted in the above inactive state is configured to support at least one usage among codebook, non-codebook, codebook and antenna-switching, or non-codebook and antenna-switching.

13. In Paragraph 10, the above commands are: the UE A UE that identifies the early SRS trigger by identifying the SRS request field included in the PEI (paging early indication).

14. In the method performed by the base station, A step of transmitting configuration information for transmitting an early SRS (sounding reference signal) to the UE (user equipment); A step of transmitting DCI (downlink control information) including an early SRS trigger to the above UE in an inactive state; A method comprising the step of receiving an SRS from the above UE.

15. Regarding base stations: At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the base station: Transmit configuration information for early SRS (sounding reference signal) transmission to UE (user equipment), and Transmit DCI (downlink control information) including an early SRS trigger to the above UE in an inactive state, and A base station that receives SRS from the above UE.

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