Method and apparatus for reporting power headroom of sounding reference signal for indicating power imbalance in wireless communication system

Abstract

The present disclosure relates to an apparatus and a method capable of effectively providing a service in a mobile communication system. A method performed by a terminal according to an embodiment of the present disclosure comprises the steps of: receiving configuration information on SRS resources from a base station; transmitting an SRS to the base station on the basis of the configuration information; and transmitting, to the base station, a power headroom report including information on transmission power of the SRS resources associated with antenna switching.

Description

Method and device for reporting power headroom of sounding reference signal for power imbalance indication in 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 for a terminal to report power headroom and additional information to a base station to improve the channel estimation accuracy of the base station during enhanced downlink channel estimation based on SRS antenna switching, and to a device 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 the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

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

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

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] As described above and with the development of wireless communication systems, various services have become available, and thus, methods for smoothly providing these services are required. In particular, methods for terminals to report power headroom and additional information to base stations are required to improve the accuracy of channel estimation of base stations.

[0009] The disclosed embodiment seeks to provide a device and method capable of effectively providing a service in a mobile communication system.

[0010] The present invention, for solving the above problems, provides a method performed by a terminal of a wireless communication system, comprising: receiving configuration information regarding SRS (sounding reference signal) resources from a base station; transmitting an SRS to the base station based on the configuration information; and transmitting a power headroom report (PHR) including information regarding transmission power of the SRS resources associated with antenna switching to the base station.

[0011] The disclosed embodiments provide devices and methods capable of effectively providing services in a mobile communication system. The effects achieved by the present disclosure are not limited to those mentioned above, and other effects not mentioned will be readily apparent to those skilled in the art to which the present disclosure pertains, based on the description below.

[0012] FIG. 1 is a diagram illustrating a medium access control (MAC) control element (CE) structure including single power headroom (PHR) information in a wireless communication system according to one embodiment of the present disclosure.

[0013] FIG. 2 is a diagram illustrating a MAC CE structure including a plurality of PHR pieces of information in a wireless communication system according to one embodiment of the present disclosure.

[0014] FIG. 3 is a diagram illustrating a sounding reference signal (SRS) antenna switching operation in a wireless communication system according to an embodiment of the present disclosure.

[0015] FIG. 4 is an example comparing a method of estimating a downlink channel based on a channel state information-reference signal (CSI-RS) and a method of estimating a downlink channel based on SRS and reciprocity in a wireless communication system according to an embodiment of the present disclosure.

[0016] FIG. 5 illustrates an example of a case in which a terminal performs SRS antenna switching and a base station acquires a downlink channel when the terminal supports 1T4R in a wireless communication system according to an embodiment of the present disclosure.

[0017] FIG. 6 is a diagram illustrating an example of a terminal structure supporting four receiving antennas in a wireless communication system according to an embodiment of the present disclosure.

[0018] FIG. 7 illustrates an example of a case where two power headroom prohibition timers operate independently in a wireless communication system according to an embodiment of the present disclosure.

[0019] FIG. 8 illustrates an example of a case in which an existing power headroom prohibition timer operates depending on whether a new power headroom prohibition timer expires in a wireless communication system according to an embodiment of the present disclosure.

[0020] FIG. 9 illustrates an example of a case in which a new power headroom prohibition timer operates depending on whether an existing power headroom prohibition timer has expired in a wireless communication system according to one embodiment of the present disclosure.

[0021] FIG. 10 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting maximum transmit power for each SRS resource of an SRS resource set for antenna switching (SRS AS) in a wireless communication system according to an embodiment of the present disclosure.

[0022] FIG. 11 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting a difference value between the maximum transmit power for each SRS resource of an SRS AS and the largest maximum transmit power among the maximum transmit powers of SRS resources within the SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0023] FIG. 12 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting power headroom for each SRS resource of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0024] FIG. 13 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting power imbalance information of SRS resources of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0025] FIG. 14 illustrates examples of a single entry power headroom MAC CE format capable of reporting power headroom and maximum transmit power and power imbalance information of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0026] FIG. 15 illustrates examples of a single entry power headroom MAC CE format that can report power headroom of a PUSCH transmitting MAC CE and power headroom and power imbalance information of an SRS AS together in a wireless communication system according to an embodiment of the present disclosure.

[0027] FIG. 16 illustrates an example of a multi-entry power headroom MAC CE format capable of additionally reporting maximum transmission power for each SRS resource of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0028] FIG. 17 illustrates a method for determining a transmission time of a physical uplink shared channel (PUSCH) performing power headroom reporting of an aperiodic (AP) SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0029] FIG. 18 illustrates another method for determining a transmission time of a PUSCH for performing power headroom reporting of an AP SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0030] FIG. 19 is a diagram illustrating the structure of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0031] FIG. 20 is a diagram illustrating the structure of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

[0033] In describing the embodiments, descriptions of technical details that are well known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to ensure that the gist of the present disclosure is conveyed more clearly without obscuring it by omitting unnecessary explanations.

[0034] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0035] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of 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. Like reference numerals designate like elements throughout the specification. In addition, when describing the present disclosure, if a specific description of a related function or configuration is determined to unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions of the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, their definitions should be made based on the contents throughout the specification.

[0036] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. In addition, although the LTE or LTE-A system may be described below as an example, the embodiments of the present disclosure may also be applied to other communication systems having a similar technical background or channel type. For example, the 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included here, and the 5G below may also be a concept that includes existing LTE, LTE-A, and other similar services. Furthermore, the present disclosure may be applied to other communication systems with some modifications, as determined by a person skilled in the art, without significantly departing from the scope of the present disclosure. The contents of the present disclosure are applicable to FDD and TDD systems.

[0037] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0038] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0039] Here, the term '~ part' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium or may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, 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'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. In addition, in an embodiment, the '~parts' may include one or more processors.

[0040] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the attached drawings.

[0041] Wireless communication systems are evolving from providing voice-oriented services in the early days to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards such as 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.

[0042] As a representative example of the above broadband wireless communication system, the LTE system adopts the OFDM (Orthogonal Frequency Division Multiplexing) method in the downlink (DL) and the SC-FDMA (Single Carrier Frequency Division Multiple Access) method in the uplink (UL). The uplink refers to a wireless link in which a terminal (User Equipment (UE) or Mobile Station (MS)) transmits data or control signals to a base station (eNode B or base station (BS)), and the downlink refers to a wireless link in which a base station transmits data or control signals to a terminal. The above multiple access method can distinguish the data or control information of each user by allocating and operating the time-frequency resources for transmitting data or control information to each user so that they do not overlap, that is, so as to achieve orthogonality.

[0043] As a future communication system beyond LTE, for example, 5G communication systems must be able to freely reflect the diverse needs of users and service providers, and thus support services that simultaneously satisfy these diverse requirements. Services being considered for 5G communication systems include enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), and Ultra Reliability Low Latency Communication (URLLC).

[0044] eMBB aims to provide data transmission rates that are significantly higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to support a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. Furthermore, 5G communication systems must simultaneously provide the peak data rate and an increased user-perceived data rate for terminals. To meet these requirements, improvements in various transmission and reception technologies, including improved multi-input, multi-output (MIMO) transmission technology, are required. Furthermore, while LTE transmits signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, 5G communication systems can meet the data transmission rates required by 5G communication systems by using a wider frequency bandwidth than 20 MHz in the 3-6 GHz or higher 6 GHz band.

[0045] At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide the IoT, mMTC requires supporting large-scale terminal connections within a cell, improved terminal coverage, enhanced battery life, and reduced terminal costs. The IoT requires the ability to support a large number of terminals (e.g., 1,000,000 terminals / km^2) within a cell, as it provides communication capabilities through the attachment of various sensors and devices. Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in shadow areas not covered by cells, such as basements, and thus may require wider coverage than other services provided by 5G communication systems. Terminals supporting mMTC must be inexpensive, and since frequent battery replacement is unlikely, they may require extremely long battery lifespans, such as 10 to 15 years.

[0046] Finally, URLLC refers to cellular-based wireless communication services used for specific mission-critical purposes. Examples include remote control of robots or machinery, industrial automation, unmanned aerial vehicles (UAVs), remote health care, and emergency alerts. Therefore, URLLC communications must offer extremely low latency and high reliability. For example, URLLC-enabled services must meet air interface latency requirements of less than 0.5 milliseconds and a packet error rate (PER) of less than 10^-5. Therefore, for services supporting URLLC, 5G systems must provide shorter Transmit Time Intervals (TTIs) than other services, and design considerations may require the allocation of extensive resources in the frequency band to ensure communication link reliability.

[0047] The three 5G services (e.g., eMBB, URLLC, and mMTC) can be multiplexed and transmitted on a single system. To meet the different requirements of each service, different transmission and reception techniques and parameters can be used. Of course, 5G is not limited to the three services described above.

[0048] Hereinafter, a / b may be understood as at least one of a or b. In addition, upper signaling may be understood as upper layer signaling or upper layer signaling.

[0049] [Uplink: PUSCH]

[0050] [PUSCH: Transmission Method Related]

[0051] Next, the scheduling method for PUSCH transmission can be described. PUSCH transmission can be dynamically scheduled by the UL grant within the DCI or can operate by configured grant Type 1 or Type 2. Dynamic scheduling instructions for PUSCH transmission can be provided in DCI format 0_0 or 0_1.

[0052] Configured grant Type 1 PUSCH transmission of the UE can be semi-statically configured by receiving configuredGrantConfig including rrc-ConfiguredUplinkGrant of [Table 1] through higher-order signaling, without receiving UL grant in DCI. Configured grant Type 2 PUSCH transmission of the UE can be semi-persistently scheduled by UL grant in DCI after receiving configuredGrantConfig not including rrc-ConfiguredUplinkGrant of [Table 1] through higher-order signaling. When PUSCH transmission operates by configured grant, parameters applied to PUSCH transmission can be applied through configuredGrantConfig of higher-order signaling of [Table 1], except for dataScramblingIdentityPUSCH, txConfig, codebookSubset, maxRank, and scaling of UCI-OnPUSCH provided by pusch-Config of [Table 2], which is higher-order signaling. If the terminal has been provided with transformPrecoder in configuredGrantConfig, which is the upper signaling of [Table 1], the terminal can apply tp-pi2BPSK in pusch-Config of [Table 2] to PUSCH transmission operated by configured grant.

[0053] [Table 1]

[0054]

[0055]

[0056] Next, the PUSCH transmission method is described. The DMRS antenna port for PUSCH transmission may be the same as the antenna port for SRS transmission. PUSCH transmission may follow a codebook-based or non-codebook-based transmission method, respectively, depending on whether the value of txConfig in the upper signaling, pusch-Config in [Table 2], is 'codebook' or 'nonCodebook'.

[0057] As described above, PUSCH transmission can be dynamically scheduled via DCI format 0_0 or 0_1, and can be semi-statically configured by configured grant. If the UE is instructed to schedule PUSCH transmission via DCI format 0_0, the UE can perform beam configuration for PUSCH transmission using pucch-spatialRelationInfoID corresponding to the UE-specific PUCCH resource corresponding to the minimum ID within the activated uplink BWP within the serving cell, and the PUSCH transmission can be based on a single antenna port. The UE may not expect scheduling for PUSCH transmission via DCI format 0_0 within a BWP where a PUCCH resource including pucch-spatialRelationInfo is not configured. If the UE has not configured txConfig in pusch-Config of [Table 2], the UE may not expect to be scheduled with DCI format 0_1.

[0058] [Table 2]

[0059]

[0060] Next, we can explain codebook-based PUSCH transmission. Codebook-based PUSCH transmission can be dynamically scheduled via DCI format 0_0 or 0_1, and can operate semi-statically based on a configured grant. When codebook-based PUSCH is dynamically scheduled via DCI format 0_1 ​​or semi-statically configured via a configured grant, the UE can determine a precoder for PUSCH transmission based on the SRS Resource Indicator (SRI), Transmission Precoding Matrix Indicator (TPMI), and transmission rank (the number of PUSCH transmission layers).

[0061] At this time, the SRI can be given through the SRS resource indicator field in the DCI or can be set through the srs-ResourceIndicator higher-order signaling. When transmitting a codebook-based PUSCH to a UE, at least one SRS resource can be set, and up to two can be set. When the UE receives the SRI through the DCI, the SRS resource indicated by the SRI provided through the DCI can refer to an SRS resource corresponding to the SRI among the SRS resources transmitted before the PDCCH including the SRI provided through the DCI. In addition, the TPMI and transmission rank can be given through the precoding information and number of layers fields in the DCI or can be set through the precodingAndNumberOfLayers higher-order signaling. The TPMI can be used to indicate the precoder applied to the PUSCH transmission. If one SRS resource is configured for the UE, the TPMI can be used to indicate the precoder to be applied in the configured one SRS resource. When multiple SRS resources are configured in a terminal, TPMI can be used to indicate the precoder to be applied in the SRS resource indicated through SRI.

[0062] The precoder to be used for PUSCH transmission can be selected from an uplink codebook having the same number of antenna ports as the nrofSRS-Ports value in the upper layer signaling, SRS-Config. In codebook-based PUSCH transmission, the UE can determine the codebook subset based on the TPMI and codebookSubset in the upper layer signaling, pusch-Config. The codebookSubset in the upper layer signaling, pusch-Config, can be set to any one of 'fullyAndPartialAndNonCoherent', 'partialAndNonCoherent', or 'nonCoherent' based on the UE capability reported by the UE to the base station. If the UE reported 'partialAndNonCoherent' as the UE capability, the UE may not expect the value of codebookSubset in the upper layer signaling to be set to 'fullyAndPartialAndNonCoherent'. Additionally, if the UE reports 'nonCoherent' as the UE capability, the UE may not expect the value of codebookSubset, which is an upper layer signaling, to be set to 'fullyAndPartialAndNonCoherent' or 'partialAndNonCoherent'. If nrofSRS-Ports in SRS-ResourceSet, which is an upper layer signaling, points to two SRS antenna ports, the UE may not expect the value of codebookSubset, which is an upper layer signaling, to be set to 'partialAndNonCoherent'.

[0063] A terminal may configure one SRS resource set in which the usage value in the upper signaling SRS-ResourceSet is set to 'codebook', and one SRS resource within the configured SRS resource set may be indicated via SRI. If multiple SRS resources are configured within an SRS resource set in which the usage value in the upper signaling SRS-ResourceSet is set to 'codebook', the terminal may expect that the value of nrofSRS-Ports within the upper signaling SRS-Resource is set to the same value for all SRS resources.

[0064] A terminal can transmit to a base station one or more SRS resources included in an SRS resource set in which the usage value is set to 'codebook' according to upper signaling, and the base station can select one of the SRS resources transmitted by the terminal and instruct the terminal to perform PUSCH transmission using transmission beam information of the selected SRS resource. At this time, in codebook-based PUSCH transmission, the SRI is used as information for selecting an index of one SRS resource and can be included in the DCI. Additionally, the base station can include in the DCI information indicating a TPMI and rank to be used by the terminal for PUSCH transmission. The terminal can perform PUSCH transmission by applying the indicated rank and the precoder indicated by the TPMI based on the transmission beam of the SRS resource indicated by the SRI, using the SRS resource indicated by the SRI.

[0065] Next, we describe non-codebook-based PUSCH transmission. Non-codebook-based PUSCH transmission can be dynamically scheduled via DCI format 0_0 or 0_1, and can operate semi-statically based on a configured grant. If at least one SRS resource is configured within an SRS resource set in which the usage value in the upper signaling SRS-ResourceSet is set to 'nonCodebook', non-codebook-based PUSCH transmission can be scheduled to the UE via DCI format 0_1.

[0066] For an SRS resource set in which the usage value in the upper signaling SRS-ResourceSet is set to 'nonCodebook', one NZP CSI-RS resource (non-zero power CSI-RS) connected to the terminal can be configured. The terminal can perform calculations for a precoder for SRS transmission through measurements on the NZP CSI-RS resource connected to the SRS resource set. If the difference between the last received symbol of the aperiodic NZP CSI-RS resource connected to the SRS resource set and the first symbol of the aperiodic SRS transmission at the terminal is less than 42 symbols, the terminal may not expect that information on the precoder for SRS transmission is updated.

[0067] If the value of resourceType in the upper signaling SRS-ResourceSet is set to 'aperiodic', the connected NZP CSI-RS can be indicated by the SRS request field in DCI format 0_1 ​​or 1_1. At this time, if the connected NZP CSI-RS resource is an aperiodic NZP CSI-RS resource, the presence of the connected NZP CSI-RS can be indicated when the value of the field SRS request in DCI format 0_1 ​​or 1_1 is not '00'. At this time, the DCI may not indicate cross-carrier or cross BWP scheduling. In addition, if the value of the SRS request indicates the presence of the NZP CSI-RS, the NZP CSI-RS can be located in the slot in which the PDCCH including the SRS request field is transmitted. At this time, the TCI states set in the scheduled subcarriers may not be set to QCL-TypeD.

[0068] If a periodic or semi-persistent SRS resource set is configured, the associated NZP CSI-RS can be indicated through the associatedCSI-RS within the upper layer signaling SRS-ResourceSet. For non-codebook-based transmission, the UE may not expect the upper layer signaling for the SRS resource, spatialRelationInfo, and the associatedCSI-RS within the upper layer signaling SRS-ResourceSet to be configured together.

[0069] When multiple SRS resources are configured for a UE, the UE can determine the precoder and transmission rank to be applied to PUSCH transmission based on the SRI indicated by the base station. At this time, the SRI can be indicated through the SRS resource indicator field in the DCI or can be configured through the srs-ResourceIndicator, which is a higher-order signaling. Similar to the codebook-based PUSCH transmission described above, when the UE receives the SRI through the DCI, the SRS resource indicated by the SRI provided through the DCI can refer to an SRS resource corresponding to the SRI among the SRS resources transmitted before the PDCCH including the SRI provided through the DCI. The UE can use one or more SRS resources for SRS transmission, and the maximum number of SRS resources that can be simultaneously transmitted in the same symbol within one SRS resource set and the maximum number of SRS resources can be determined by the UE capability reported by the UE to the base station. At this time, the SRS resources that the UE simultaneously transmits can occupy the same RB. A terminal can configure one SRS port for each SRS resource. Only one SRS resource set with the usage value set to "nonCodebook" within the upper-level signaling SRS-ResourceSet can be configured, and up to four SRS resources for non-codebook-based PUSCH transmission can be configured.

[0070] A base station can transmit one NZP-CSI-RS associated with an SRS resource set to a terminal, and the terminal can calculate a precoder to be used when transmitting one or more SRS resources within the SRS resource set based on a result measured upon reception of the NZP-CSI-RS. When the terminal transmits one or more SRS resources within an SRS resource set in which usage is set to 'nonCodebook' to the base station, the terminal can apply the calculated precoder described above, and the base station can select one or more SRS resources from among the received one or more SRS resources. At this time, in non-codebook based PUSCH transmission, an SRI can indicate an index that can express a combination of one or more SRS resources, and the SRI can be included in the DCI. At this time, the number of SRS resources indicated by the SRI transmitted by the base station can be the number of transmission layers of the PUSCH, and the terminal can transmit the PUSCH by applying the precoder applied to the SRS resource transmission to each layer.

[0071] [PUSCH: Transmission Power Related]

[0072] Below, a method for determining the transmission power of an uplink data channel in a 5G system is specifically described.

[0073] In a 5G system, the transmission power of an uplink data channel can be determined using the following [Mathematical Formula 1].

[0074] [Mathematical Formula 1]

[0075]

[0076] In [Mathematical Formula 1], j represents the grant type of PUSCH. Specifically, j = 0 is a PUSCH grant for random access response, j = 1 is a configured grant, and j {2,3,..., J-1} means dynamic grant. means the maximum output power set to the terminal for carrier f of supporting cell c for PUSCH transmission occasion i. is set as a higher layer parameter and can be determined through upper layer settings and SRI (in case of dynamic grant PUSCH). It is a parameter composed of the sum of . means the bandwidth for resource allocation expressed as the number of resource blocks for PUSCH PUSCH transmission occasion i, It means a value determined according to the MCS (Modulation Coding Scheme) and the type of information transmitted via PUSCH (e.g., whether UL-SCH is included or CSI is included, etc.). refers to a value that can be determined (in case of dynamic grant PUSCH) through upper layer settings and SRI (SRS Resource Indicator) as a value to compensate for path loss. is the reference signal index q d It means the downlink path loss estimate estimated by the terminal through the reference signal, and the reference signal index q. dThe UE can decide this via upper layer configuration and SRI (in case of dynamic grant PUSCH or configured grant PUSCH based on ConfiguredGrantConfig that does not include upper layer configuration rrc-ConfiguredUplinkGrant (type 2 configured grant PUSCH)) or via upper layer configuration. can be supported in both accumulation and absolute modes as closed loop power adjustment values. If the upper layer parameter tpc-Accumulation is not set in the terminal, the closed loop power adjustment value can be determined in accumulation mode. In this case, is the closed loop power adjustment value for the previous PUSCH transmission occasion i-i0 to transmit PUSCH transmission occasion i-i0. PUSCH Transmitting PUSCH transmission occasion i from (i-i0)-1 symbols K PUSCH (i) Between symbols, the sum of the TPC command values ​​for the closed loop index l received via DCI is determined. If the upper layer parameter tpc-Accumulation is set in the terminal, is the TPC command value for the closed loop index l received via DCI. is determined. The closed loop index l can be set to 0 or 1 if the upper layer parameter twoPUSCH-PC-AdjustmentStates is set in the terminal, and its value can be determined through the upper layer configuration and SRI (in case of dynamic grant PUSCH). The TPC command field and TPC value in the DCI according to the accumulation method and the absolute method. The mapping relationship can be defined as shown in [Table 3] below.

[0077] [Table 3]

[0078]

[0079] [PHR related]

[0080] The power headroom report may mean that the UE measures and transmits to the base station the difference between the nominal UE maximum transmit power and the estimated power for uplink transmission (e.g., indicating the available transmit power of the UE). The power headroom report may be used to support power-aware packet scheduling. The estimated power for uplink transmission may be the estimated power for UL-SCH (PUSCH) transmission per activated serving cell, the estimated power for UL-SCH and PUCCH transmission in SpCell of another MAC entity (e.g., E-UTRA MAC entity in EN-DC, NE-DC, and NGEN-DC cases in 3GPP standards), the estimated power for SRS transmission per activated serving cell, etc. The UE may trigger the power headroom report if any of the following trigger events are met:

[0081] - [Trigger Event 1] When the upper layer parameter phr-ProhibitTimer expires and the MAC entity has uplink resources for new transmission, the path loss for at least one activated supporting cell may change by more than the upper layer parameter phr-Tx-PowerFactorChange dB since the most recent PHR transmission. Here, the activated downlink bandwidth part for the at least one activated supporting cell may not be a dormant bandwidth part. In this case, the path loss change for one cell may be determined as the difference between the currently measured path loss with respect to the current path loss reference and the path loss measured at that point in time with respect to the path loss reference at the time of the most recent PHR transmission.

[0082] - [Trigger Event 2] The upper layer parameter phr-PeriodicTimer may expire.

[0083] - [Trigger Event 3] Power headroom reporting function may be set or reset by a higher layer, rather than a setting or reset that does not support power headroom reporting.

[0084] - [Trigger Event 4] A SCell may be activated for any MAC entity having an uplink for which firstActiveDownlinkBWP-Id is not set to dormant bandwidth part. The firstActiveDownlinkBWP-Id may mean the identifier of the DL BWP to be activated when performing RRC (re)configuration (if configured for the SpCell) or the identifier of the DL BWP to be used when activating the SCell (if configured for the SCell).

[0085] - [Trigger Event 5] A PSCell is added (e.g., a new PSCell is added or changed).

[0086] - [Trigger Event 6] The upper layer parameter phr-PrhoibitTimer has expired, and for any activated supporting cells of any MAC entity with uplink configured when the MAC entity has uplink resources for a new transmission, both the following conditions a) and b) can be met:

[0087] a) There are uplink resources allocated for transmission or the PUCCH can be transmitted to the cell.

[0088] b) When a MAC entity has uplink resources for transmission or transmits PUCCH to a cell, the required power backoff due to power management for that cell may be greater than the upper layer parameter phr-Tx-PowerFactorChange dB since the most recent PHR transmission.

[0089] - [Trigger Event 7] The activated bandwidth part of the SCell for any MAC entity with configured uplink can be changed from the dormant bandwidth part to the non-dormant downlink bandwidth part.

[0090] - [Trigger Event 8] If the upper layer parameter mpe-Reporting-FR2 is set in the UE to indicate whether to report MPE P-MPR (Maximum allowed UE output power reduction) to satisfy the maximum permissible exposure (MPE) in FR2, and mpe-ProhibitTimer may not operate, then the measured P-MPR applied to satisfy the FR2 MPE requirement for at least one activated FR2-capable cell since the most recent power headroom report may be greater than or equal to the upper layer parameter mpe-Threshold, if the power headroom report is referred to as 'MPE P-MPR report'.

[0091] Power headroom reporting may be triggered based on the above trigger events, and the terminal may decide to report power headroom based on the following additional conditions.

[0092] - [Additional conditions for temporary required power backoff] When the required power backoff is temporarily reduced (e.g., up to tens of milliseconds) due to power management, the MAC entity may not trigger power headroom reporting. If the required power backoff is temporarily reduced and power headroom reporting is triggered by other trigger events, this may result in P representing the ratio between the maximum power and the remaining (available) power. CMAX,f,c / PH values ​​may need to be prevented from being temporarily reduced. For example, a temporary power backoff may not trigger the PHR. For example, if the PHR is triggered by another PHR trigger event (such as the expiration of a periodic timer), a condition may be added so that the PH reflecting the temporary power reduction due to the demand power backoff is not reported, and the PH excluding the effect of the demand power backoff is reported.

[0093] - [Power headroom reporting conditions according to terminal implementation] If one HARQ process is set to cg-RetransmissionTimer and a power headroom report has already been included in the MAC PDU for transmission by the corresponding HARQ process but transmission through the lower layer has not yet been performed, the method of processing the corresponding power headroom report can be determined according to the terminal implementation.

[0094] If one or more of the above trigger events occur to trigger a power headroom report, and the uplink transmission resources allocated through the downlink control information can accommodate a MAC entity and a subheader for the power headroom report, the terminal can perform a power headroom report through the corresponding uplink resources. In this case, the corresponding uplink resources may refer to resources for uplink transmission scheduled by the first downlink control information format (DCI format) that schedules the initial transmission of a transport block (TB) after the power headroom trigger or by the first uplink grant. For example, after the power headroom trigger occurs, the terminal can perform a power headroom report through an uplink transmission scheduled by the first downlink control information format or the first uplink grant among the uplink resources that can accommodate a MAC entity and a subheader for the power headroom. Alternatively, after a power headroom trigger occurs, the terminal can perform power headroom reporting through a configured grant PUSCH transmission capable of accommodating a MAC entity for power headroom and its subheader.

[0095] When reporting power headroom for a specific cell, a UE may select and calculate one of two types of power headroom information. The first type is actual PHR, which may be power headroom information calculated based on the transmit power of an uplink signal (e.g., PUSCH) actually transmitted. The second type is virtual PHR (or reference format), which may be power headroom information calculated based on transmit power parameters set in a higher layer, even though there is no actual uplink signal (e.g., PUSCH) transmitted. After a power headroom report is triggered, the UE may calculate the actual PHR based on the downlink control information received up to a point including the PDCCH monitoring interval in which the first DCI format scheduling the PUSCH to transmit the MAC CE including the power headroom report, as described above, and the higher layer information for periodic / semi-persistent SRS transmission and configured grant transmission. If the UE receives downlink control information or decides to transmit periodic / semi-persistent SRS or configured grant after the PDCCH monitoring period in which the first DCI format is received, the UE can calculate virtual PHR for the corresponding cell. Alternatively, after the power headroom report is triggered, the UE calculates T' corresponding to the PUSCH preparation process time described above based on the first uplink symbol of the configured grant PUSCH that can transmit the power headroom information. proc,2 =T proc,2The actual PHR can be calculated based on the downlink control information received up to the previous point in time and the upper layer information for periodic / semi-persistent SRS transmission and configured grant transmission. If T' is based on the first uplink symbol of the configured grant PUSCH, proc,2 If the terminal receives downlink control information after the previous point in time, or decides to transmit periodic / semi-persistent SRS or configured grant, the terminal can calculate a virtual PHR for the corresponding cell.

[0096] If the terminal calculates the actual PHR based on the actual PUSCH transmission, the power headroom reporting information for the support cell c, carrier f, bandwidth part b, and PUSCH transmission time point i can be expressed as in the following [Mathematical Formula 2].

[0097] [Equation 2]

[0098]

[0099] As another example, if a terminal calculates a virtual PHR based on a transmission power parameter set in a higher layer, the power headroom reporting information for support cell c, carrier f, bandwidth part b, and PUSCH transmission time point i can be expressed as in the following [Mathematical Formula 3].

[0100] [Equation 3]

[0101]

[0102] According to the above [Mathematical Equation 2], power headroom information can be calculated by using the difference in transmission power for PUSCH transmission occasion i at the maximum output power. According to [Mathematical Equation 3], parameters related to MPR (Maximum Power Reduction) (e.g., MPR, A-MPR (Additional MPR), P-MPR (Power Management MPR), etc.) T c The maximum output power when assuming 0 is and default transmit power parameters (e.g., , p0 and alpha of P0-PUSCH-AlphaSetId=0, corresponding to pusch-PathlossReferenceRS-Id=0 And the power headroom information can be calculated using the difference of the reference PUSCH transmission power using the closed loop power adjustment value with the closed loop index l = 0). The description of each variable in the above [Mathematical Expressions 2] and [Mathematical Expressions 3] can refer to the description of the variables in the above [Mathematical Expression 1]. The above A-MPR can be an MPR that satisfies the additional emission requirement indicated by the base station by the upper layer signaling (for example, by combining the additionalSpectrumEmission indicated by RRC and the NR freq. band (Table 6.2.3.1-1A in TS 38.101-1), the network signaling label is identified, and the A-MPR value accordingly is defined as Table 6.2.3.1-1 in TS 38.101-1). The above P-MPR is a maximum allowed UE output power reduction for serving cell c, and its purpose may be an MPR that can satisfy applicable electromagnetic energy absorption requirements. The above A-MPR and P-MPR may refer to 3GPP standard TS 38.101-1 section 6.2. In a communication system to which the present disclosure may be applied, the first type of power headroom information may mean power headroom information for PUSCH transmission power. In addition, the second type of power headroom information may mean power headroom information for PUCCH transmission power. In addition, the third type of power headroom information may mean power headroom information for SRS transmission power. Meanwhile, the present disclosure is not limited thereto.

[0103] If MR-DC or UL-CA is not supported, the base station may set the upper layer parameter 'multiplePHR' to 'false' for the corresponding terminal.

[0104] FIG. 1 is a diagram illustrating a medium access control (MAC) control element (CE) structure including a single power headroom (PHR) information in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 1, setting 'multiplePHR' to 'false' may mean that the terminal supports power headroom reporting for the PCell with a MAC CE having a single entry, as shown in (110) of FIG. 1. Each field of FIG. 1 may be defined as shown in [Table 4] below. However, this is merely an example and the present disclosure is not limited thereto.

[0105] [Table 4]

[0106]

[0107]

[0108] If the terminal supports MR-DC (multi-RAT dual connectivity) or UL-CA (uplink carrier aggregation), the base station can set the upper layer parameter 'multiplePHR' to 'true' for the corresponding terminal to perform power headroom reporting for each supported cell.

[0109] FIG. 2 is a diagram illustrating a MAC CE structure including multiple PHR information in a wireless communication system according to an embodiment of the present disclosure. Referring to FIG. 2, setting 'multiplePHR' to 'true' may mean that the terminal supports power headroom reporting for multiple supported cells with a MAC CE having multiple entries, such as the first format (200) or the second format (202) illustrated in FIG. 2.

[0110] The first format (200) of FIG. 2 may be a PHR MAC CE format that can be used when multiple serving cells are set and the largest index value among the serving cells is less than 8. The second format (202) of FIG. 2 may be a PHR MAC CE format that can be used when multiple serving cells are set and the largest index value among the serving cells is greater than or equal to 8. Unlike the PHR MAC CE format illustrated in FIG. 1, the first format (200) or the second format (202) illustrated in FIG. 2 may have a variable size depending on the set or number of serving cells set. The information may include a second type of PH information for a SpCell (special cell) of another MAC entity (e.g., LTE) and a first type of PH information for a PCell. When the largest index value among the serving cells is less than 8, the field indicating the serving cell information may be configured as one octet. If the largest value of the index among the corresponding serving cells is greater than or equal to 8, a field indicating serving cell information may be composed of 4 octets. Power headroom information may be included in the PHR MAC CE according to the order of the serving cell index. When power headroom reporting is triggered, the MAC entity may transmit the PHR MAC CE including the power headroom information through the transmittable PUSCH. At this time, whether the power headroom information is calculated based on actual transmission (e.g., whether it is an actual PHR) or calculated based on a transmission power parameter set in a higher layer (e.g., whether it is a virtual PHR) is determined at a specific time point (e.g., a time point including a PDCCH monitoring period in which the first DCI format is detected or T' in the first symbol of the first PUSCH, as described above. proc,2It can be determined based on the upper signal and downlink control information received up to the previous point in time. Meanwhile, the fields of the PHR MAC CE format illustrated in Fig. 2 may have the same meaning (definition) as most of the fields of the PHR MAC CE format illustrated in Fig. 1, and C i and V can have the same meaning as described in [Table 5] below.

[0111] [Table 5]

[0112]

[0113] [Uplink: RS]

[0114] [SRS related]

[0115] Next, we describe an uplink channel estimation method using the Sounding Reference Signal (SRS) transmission of a terminal. The base station can configure at least one SRS configuration for each uplink BWP to convey configuration information for SRS transmission to the terminal, and can also configure at least one SRS resource set for each SRS configuration. For example, the base station and the terminal can exchange the following upper-level signaling information to convey information regarding the SRS resource set.

[0116] - srs-ResourceSetId: SRS resource set index

[0117] - srs-ResourceIdList: A set of SRS resource indices referenced in the SRS resource set.

[0118] - resourceType: This is the time axis transmission setting of the SRS resource referenced in the SRS resource set, and can be set to one of 'periodic', 'semi-persistent', and 'aperiodic'. If set to 'periodic' or 'semi-persistent', associated CSI-RS information can be provided depending on the usage of the SRS resource set. If set to 'aperiodic', an aperiodic SRS resource trigger list and slot offset information can be provided, and associated CSI-RS information can be provided depending on the usage of the SRS resource set.

[0119] - usage: This is a setting for the usage of the SRS resource referenced in the SRS resource set, and can be set to one of 'beamManagement', 'codebook', 'nonCodebook', and 'antennaSwitching'.

[0120] - alpha, p0, pathlossReferenceRS, srs-PowerControlAdjustmentStates: Provides parameter settings for adjusting the transmission power of the SRS resource referenced in the SRS resource set.

[0121] The terminal can understand that the SRS resource included in the set of SRS resource indices referenced in the SRS resource set follows the information set in the SRS resource set.

[0122] In addition, the base station and the terminal may transmit and / or receive upper layer signaling information to convey individual configuration information for the SRS resource. For example, the individual configuration information for the SRS resource may include time-frequency axis mapping information within the slot of the SRS resource, which may include information about frequency hopping within or between slots of the SRS resource. In addition, the individual configuration information for the SRS resource may include a time-domain transmission configuration of the SRS resource, which may be set to one of 'periodic', 'semi-persistent', and 'aperiodic'. This may be restricted to have the same time-domain transmission configuration as the SRS resource set including the SRS resource. If the time-domain transmission configuration 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-domain transmission configuration.

[0123] The base station can activate, deactivate, or trigger SRS transmission to the UE through higher layer signaling, including RRC signaling or MAC CE signaling, or L1 signaling (e.g., DCI). For example, the base station can activate or deactivate periodic SRS transmission to the UE through higher layer signaling. The base station can instruct the UE to activate an SRS resource set with resourceType set to periodic through higher layer signaling, and the UE can transmit an SRS resource referenced in the activated SRS resource set. The time-frequency domain resource mapping within the slot of the transmitted SRS resource can follow the resource mapping information set in the SRS resource, and the slot mapping, including the transmission period and slot offset, can follow periodicityAndOffset set in the SRS resource. In addition, the spatial domain transmission filter applied to the transmitted SRS resource can refer to the spatial relation information set in the SRS resource, or the associated CSI-RS information set in the SRS resource set that includes the SRS resource. A terminal can transmit SRS resources within an activated uplink BWP for periodic SRS resources activated through upper layer signaling.

[0124] For example, a base station can activate or deactivate semi-persistent SRS transmission to a terminal through upper layer signaling. The base station can instruct the terminal to activate an SRS resource set through MAC CE signaling, and the terminal can transmit an SRS resource referenced in the activated SRS resource set. The SRS resource set activated through MAC CE signaling can be limited to an SRS resource set with resourceType set to semi-persistent. The time-frequency domain resource mapping within the slot of the transmitted SRS resource can follow the resource mapping information configured in the SRS resource, and the slot mapping including the transmission period and slot offset can follow periodicityAndOffset configured in the SRS resource. In addition, the spatial domain transmission filter applied to the transmitted SRS resource can refer to the spatial relation information configured in the SRS resource, or the associated CSI-RS information configured in the SRS resource set including the SRS resource. If spatial relation info is configured in an SRS resource, the spatial domain transmission filter can be determined by referring to the configuration information for spatial relation info transmitted through MAC CE signaling that activates semi-persistent SRS transmission without following it. The terminal can transmit SRS resources within the activated uplink BWP for the semi-persistent SRS resource activated through upper layer signaling.

[0125] For example, a base station can trigger aperiodic SRS transmission to a terminal via DCI. The base station can indicate one of the aperiodic SRS resource triggers (aperiodicSRS-ResourceTrigger) via the SRS request field of the DCI. The terminal can understand that an SRS resource set including the aperiodic SRS resource trigger indicated via DCI in the aperiodic SRS resource trigger list among the configuration information of the SRS resource set has been triggered. The terminal can transmit an SRS resource referenced in the triggered SRS resource set. The time-frequency domain resource mapping within the slot of the transmitted SRS resource can follow the resource mapping information configured in the SRS resource. In addition, the slot mapping of the transmitted SRS resource can be determined through a slot offset between a PDCCH including the DCI and the SRS resource, which can refer to value(s) included in a slot offset set configured in the SRS resource set. Specifically, the slot offset between the PDCCH including DCI and the SRS resource can be applied by applying the value indicated in the time domain resource assignment field of the DCI among the offset value(s) included in the slot offset set configured in the SRS resource set. In addition, the spatial domain transmission filter applied to the transmitted SRS resource can refer to the spatial relation information configured in the SRS resource, or can refer to the associated CSI-RS information configured in the SRS resource set including the SRS resource. The UE can transmit the SRS resource within the activated uplink BWP for the aperiodic SRS resource triggered through the DCI.

[0126] When a base station triggers aperiodic SRS transmission to a terminal through DCI, a minimum time interval may be required between a PDCCH including the DCI that triggers aperiodic SRS transmission and the SRS to be transmitted, so that the terminal can transmit the SRS by applying configuration information for the SRS resource. The time interval for SRS transmission of the terminal can be defined as the number of symbols between the last symbol of the PDCCH including the DCI that triggers aperiodic SRS transmission and the first symbol to which the first SRS resource to be transmitted among the SRS resource(s) is mapped. The minimum time interval can be determined with reference to the PUSCH preparation procedure time required for the terminal to prepare for PUSCH transmission. In addition, the minimum time interval can have different values ​​depending on the usage of the SRS resource set including the SRS resource to be transmitted. For example, the minimum time interval can be determined as N2 symbols, which are defined by considering the terminal processing ability according to the capability of the terminal with reference to the PUSCH preparation procedure time of the terminal. In addition, considering the usage of the SRS resource set including the SRS resource being transmitted, if the usage of the SRS resource set is set to 'codebook' or 'antennaSwitching', the minimum time interval can be set to N2 symbols, and 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 may transmit an aperiodic SRS if the time interval for aperiodic SRS transmission is greater than or equal to the minimum time interval, and may ignore the DCI that triggers the aperiodic SRS if the time interval for aperiodic SRS transmission is less than the minimum time interval.

[0127] [Table 6]

[0128]

[0129] The spatialRelationInfo setting information in [Table 6] above can be applied to the beam information of a reference signal and the beam used for SRS transmission. For example, the spatialRelationInfo setting can include information such as [Table 7] below. Of course, it is not limited to the following example.

[0130] [Table 7]

[0131]

[0132] Referring to the above spatialRelationInfo setting, the terminal can receive an index of a reference signal to be referenced in order to use beam information of a specific reference signal from the base station, that is, an SS / PBCH block index, a CSI-RS index, or an SRS index. The upper signaling referenceSignal is setting information indicating which beam information of a reference signal is to be referenced for the corresponding SRS transmission, and ssb-Index can mean the index of the SS / PBCH block, csi-RS-Index can mean the index of the CSI-RS, and srs can mean the index of the SRS, respectively. If the value of the upper signaling referenceSignal is set to 'ssb-Index', the terminal can apply the reception beam used when receiving the SS / PBCH block corresponding to ssb-Index as the transmission beam of the corresponding SRS transmission. If the value of the upper signaling referenceSignal is set to 'csi-RS-Index', the terminal can apply the reception beam used when receiving the CSI-RS corresponding to the csi-RS-Index as the transmission beam for the corresponding SRS transmission. If the value of the upper signaling referenceSignal is set to 'srs', the terminal can apply the transmission beam used when transmitting the SRS corresponding to the srs as the transmission beam for the corresponding SRS transmission.

[0133] [SRS: Antenna switching]

[0134] Below, SRS for antenna switching is described.

[0135] The SRS transmitted from the terminal can be used by the base station to acquire DL CSI (Channel State Information) information (e.g., DL CSI acquisition). As a specific example, in a single cell or multi-cell (e.g., carrier aggregation (CA)) situation based on TDD (Time Division Duplex), the BS (Base Station) can schedule the transmission of SRS to the UE (User Equipment) and then measure the SRS transmitted from the UE. In this case, the base station can regard the uplink channel information estimated based on the SRS transmitted from the terminal as downlink channel information, assuming reciprocity between the DL (downlink) / UL (uplink) channels, and can perform downlink signal / channel scheduling for the terminal using this. In this case, the terminal can be configured to use antenna switching for the SRS for acquiring downlink channel information from the base station.

[0136] For example, according to the standard (e.g., 3gpp TS38.214), the usage of SRS can be set to the base station and / or terminal using a higher layer parameter (e.g., usage of RRC parameter SRS-ResourceSet). Here, the usage of SRS can be set to beam management usage, codebook transmission usage, non-codebook transmission usage, antenna switching usage, etc.

[0137] As described above, if the terminal receives the usage parameter in the upper layer signaling SRS-ResourceSet from the base station as 'antennaSwitching', the terminal can receive at least one upper layer signaling configuration from the base station according to the reported terminal capability. At this time, the terminal can report 'supportedSRS-TxPortSwitch' as ​​the terminal capability, and the value can be as follows. In the following, 'mTnR' can mean the terminal capability that supports transmission through m antennas and reception through n antennas.

[0138] - 't1r2': Terminal capability report value indicating that the terminal is capable of 1T2R operation.

[0139] - 't1r1-t1r2': Terminal capability report value indicating that the terminal is capable of 1T1R or 1T2R operation.

[0140] - 't2r4': Terminal capability report value indicating that the terminal is capable of 2T4R operation.

[0141] - 't1r4': Terminal capability report value indicating that the terminal is capable of 1T4R operation.

[0142] - 't1r6': Terminal capability report value indicating that the terminal is capable of 1T6R operation.

[0143] - 't1r8': Terminal capability report value indicating that the terminal is capable of 1T8R operation.

[0144] - 't2r6': Terminal capability report value indicating that the terminal is capable of 2T6R operation.

[0145] - 't2r8': Terminal capability report value indicating that the terminal is capable of 2T8R operation.

[0146] - 't4r8': Terminal capability report value indicating that the terminal is capable of 4T8R operation.

[0147] - 't1r1-t1r2-t1r4': Terminal capability report value indicating that the terminal is capable of 1T1R, 1T2R, or 1T4R operation.

[0148] - 't1r4-t2r4': Terminal capability report value indicating that the terminal is capable of 1T4R or 2T4R operation.

[0149] - 't1r1-t1r2-t2r2-t2r4': Terminal capability report value indicating that the terminal is capable of 1T1R, 1T2R, 2T2R, or 2T4R operation.

[0150] - 't1r1-t1r2-t2r2-t1r4-t2r4': Terminal capability report value indicating that the terminal is capable of 1T1R, 1T2R, 2T2R, 1T4R, or 2T4R operation.

[0151] - 't1r1': Terminal capability report value indicating that the terminal is capable of 1T1R operation.

[0152] - 't2r2': Terminal capability report value indicating that the terminal is capable of 2T2R operation.

[0153] - 't1r1-t2r2': Terminal capability report value indicating that the terminal is capable of 1T1R or 2T2R operation.

[0154] - 't4r4': Terminal capability report value indicating that the terminal is capable of 4T4R operation.

[0155] - 't1r1-t2r2-t4r4': Terminal capability report value indicating that the terminal is capable of 1T1R, 2T2R, or 4T4R operation.

[0156] FIG. 3 is a diagram illustrating an SRS antenna switching operation in a wireless communication system according to an embodiment of the present disclosure.

[0157] Referring to FIG. 3, a terminal may be configured to operate in 1T4R mode and may be configured with two aperiodic SRS resource sets (e.g., SRS resource sets #0 and #1). The terminal may receive a PDCCH from a base station (300) and, through the PDCCH, may be instructed to initiate an aperiodic SRS trigger for SRS resource set #0 (310) and SRS resource set #1 (320). At this time, the slot offset value for SRS resource set #0 (310) may be configured as slotOffset, which is a higher layer signaling, and the value may be 1. In addition, the terminal may perform aperiodic SRS transmission for SRS resource set #0 at a position 1 slot later (e.g., in slot #1) from the slot in which the PDCCH is received. In addition, the slot offset value for SRS resource set #1 (320) may be configured as slotOffset, which is a higher layer signaling, and the value may be 2. Additionally, the terminal may perform aperiodic SRS transmission for SRS resource set #1 at a position two slots later (e.g., in slot #2) from the slot in which the PDCCH is received.

[0158] SRS resource #0 (311) and SRS resource #1 (312) included in SRS resource set #0 (310) can be transmitted at different OFDM symbol positions within slot #1, and at this time, Y number of OFDM symbols can exist as a guard interval between SRS resources #0 and #1 (313). In addition, when transmitting for SRS resource #0 (330), the terminal can perform SRS transmission by connecting one SRS port to the first receiving antenna port (335) of the terminal. When transmitting for SRS resource #1 (340), the terminal can perform SRS transmission by connecting one SRS port to the second receiving antenna port (345) of the terminal.

[0159] SRS resource #2 (321) and SRS resource #3 (322) included in SRS resource set #1 (320) are transmitted at different OFDM symbol positions within slot #1, and Y number of OFDM symbols may exist as a guard interval between SRS resources #2 and #3 (323). In addition, when transmitting for SRS resource #2 (350), the terminal can perform SRS transmission by connecting one SRS port to the third receiving antenna port (355) of the terminal. When transmitting for SRS resource #3 (360), the terminal can perform SRS transmission by connecting one SRS port to the fourth receiving antenna port (365) of the terminal.

[0160] By connecting the four SRS resources #0 to #3 described above to the receiving antenna ports of different terminals and transmitting SRS, the terminal can transmit SRS from all different receiving antenna ports so as to obtain channel information connected to all receiving antennas of the terminal. In addition, by transmitting SRS from all different receiving antenna ports of the terminal, the base station can obtain channel information between the base station and the terminal and utilize it for uplink or downlink scheduling.

[0161] [UE capability]

[0162] [Regarding terminal capability reporting]

[0163] In LTE and NR, a terminal, while connected to a serving base station, can perform a procedure to report its supported capabilities to the base station. In the description below, this is referred to as a UE capability report.

[0164] A base station can transmit a UE capability inquiry message requesting a capability report to a connected terminal. The UE capability inquiry message can include a UE capability request for each RAT (radio access technology) type of the base station. The UE capability request for each RAT type can include information on a combination of supported frequency bands, etc. In addition, in the case of the UE capability inquiry message, UE capabilities for multiple RAT types can be requested through a single RRC message container transmitted by the base station, or the base station can include multiple UE capability inquiry messages including UE capability requests for each RAT type and transmit them to the terminal. That is, the UE capability inquiry is repeated multiple times in a single message, and the terminal can compose a corresponding UE capability information message and report it multiple times. In the next-generation mobile communication system, a UE capability request can be made for MR-DC (Multi-RAT dual connectivity), including NR, LTE, and EN-DC (E-UTRA - NR dual connectivity). Additionally, the terminal capability inquiry message may generally be transmitted initially after the terminal is connected to the base station, but may also be requested under any conditions when the base station needs it.

[0165] In one embodiment, a terminal that receives a UE capability report request from a base station may configure terminal capability based on the RAT type and band information requested from the base station. The method by which a terminal configures UE capability in an NR system may be as follows.

[0166] 1. If the UE receives a list of LTE and / or NR bands through a UE capability request from the base station, the UE can configure a band combination (BC) for EN-DC and NR stand-alone (SA). That is, a candidate list of BCs for EN-DC and NR SA can be configured based on the bands requested to the base station via FreqBandList. In addition, the band priorities can be prioritized in the order listed in FreqBandList.

[0167] 2. If the base station requests UE capability reporting by setting the "eutra-nr-only" flag or the "eutra" flag, the UE may completely remove NR SA BCs from the configured BC candidate list. This action can only occur when the LTE base station (eNB) requests the "eutra" capability.

[0168] 3. Afterwards, the terminal can remove fallback BCs from the BC candidate list constructed in the above step. Here, a fallback BC refers to a BC obtained by removing at least one band corresponding to an SCell from a random BC. This step can be omitted because the BC before removing the band corresponding to at least one SCell can already cover the fallback BC. This step also applies to MR-DC, i.e., to LTE bands. The BCs remaining after this step can be considered the final "candidate BC list."

[0169] 4. The terminal can select BCs to report by selecting BCs that match the requested RAT type from the final "candidate BC list" above. In this step, the terminal can construct the supportedBandCombinationList in a set order. That is, the terminal can construct BCs and UE capabilities to report according to the preset rat-Type order (nr -> eutra-nr -> eutra). In addition, the terminal can construct a featureSetCombination for the constructed supportedBandCombinationList, and construct a list of "candidate feature set combinations" from the candidate BC list after removing the list for the fallback BC (which contains capabilities of the same or lower level). The "candidate feature set combinations" above include feature set combinations for both NR and EUTRA-NR BCs, and can be obtained from the feature set combinations of the UE-NR-Capabilities and UE-MRDC-Capabilities containers.

[0170] 5. Also, if the requested rat Type is eutra-nr and has influence, featureSetCombinations can be included in both containers, UE-MRDC-Capabilities and UE-NR-Capabilities. However, the feature set of NR can only be included in UE-NR-Capabilities.

[0171] After terminal capabilities are configured, the terminal can transmit a terminal capability information message containing the terminal capabilities to the base station. Based on the terminal capabilities received from the terminal, the base station can then perform appropriate scheduling and transmission and / or reception management for the terminal.

[0172] [Beginning]

[0173] [Introduction to the Example]

[0174] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. The contents of the present disclosure can be applied to FDD and TDD systems. In the present disclosure below, upper signaling (or upper layer signaling) refers to a signal transmission method in which a base station transmits a signal to a terminal using a downlink data channel of a physical layer, or a terminal transmits a signal to a base station using an uplink data channel of a physical layer, and may also be referred to as RRC signaling, PDCP signaling, or MAC (medium access control) control element (MAC control element; MAC CE).

[0175] In the present disclosure, when determining whether cooperative communication is applied, the terminal may use various methods, such as having the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied have a specific format, or including a specific indicator that indicates whether cooperative communication is applied, or scrambled with a specific RNTI by the PDCCH(s) that allocate the PDSCH to which cooperative communication is applied, or assuming cooperative communication is applied in a specific section indicated by a higher layer. For the convenience of the following description, the case where the terminal receives the PDSCH to which cooperative communication is applied based on conditions similar to the above will be referred to as the NC-JT case.

[0176] In the present disclosure, determining the priority between A and B may be referred to in various ways, such as selecting a higher priority according to a predetermined priority rule and performing an action corresponding to it, or omitting or dropping an action for a lower priority.

[0177] In the present disclosure below, the above examples are described through multiple embodiments, but they are not independent and one or more embodiments may be applied simultaneously or in combination.

[0178] For convenience in the following description of the present disclosure, cells, transmission points, panels, beams, and / or transmission directions, which 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 uniformly described 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.

[0179] Hereinafter, the base station is an entity that performs resource allocation of the terminal, and may be at least one of a gNode B, a gNB, an eNode B, a Node B, a BS (Base Station), a wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. Hereinafter, the embodiments of the present disclosure will be described using a 5G system as an example, but the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type. For example, this may include LTE or LTE-A mobile communication and mobile communication technologies developed after 5G. Therefore, the 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 determined by a person skilled in the art. The contents of the present disclosure can be applied to FDD and TDD systems.

[0180] In the following description of the present disclosure, upper layer signaling may be signaling corresponding to at least one or a combination of one or more signalings.

[0181] - MIB (Master Information Block)

[0182] - SIB (System Information Block) or SIB

[0183] - RRC (Radio Resource Control)

[0184] - MAC (Medium Access Control) CE (Control Element)

[0185] Additionally, L1 signaling may be signaling corresponding to at least one or a combination of one or more signaling methods using a physical layer channel or signaling.

[0186] - PDCCH (Physical Downlink Control Channel)

[0187] - DCI (Downlink Control Information)

[0188] - UE-specific DCI

[0189] - Group common DCI

[0190] - Common DCI

[0191] - Scheduling DCI (e.g. DCI used for scheduling downlink or uplink data)

[0192] - Non-scheduled DCI (e.g. DCI not intended for scheduling downlink or uplink data)

[0193] - PUCCH (Physical Uplink Control Channel)

[0194] - UCI (Uplink Control Information)

[0195] The term “slot” used in the present disclosure below is a general term that may refer to a specific time unit corresponding to a TTI (Transmit Time Interval), and may specifically mean a slot used in a 5G system, or a slot or subframe used in a 4G LTE system.

[0196] [Start of the implementation]

[0197] As previously explained in antenna switching, since reciprocity exists between the uplink and downlink channels in a TDD system, if channel information for one of the two channels can be acquired, information for the other channel can also be estimated. Since the base station is configured with more transmit antennas than the terminal, in order to estimate the downlink channel between the base station and the terminal, the base station must transmit to the terminal a greater number of reference signal ports than in order to estimate the uplink channel. This means that in order to orthogonally estimate the downlink channel between each transmit antenna port of the base station and all terminal antenna ports, a number of channel state information-reference signals (CSI-RS) equal to the number of transmit antennas of the base station may be required. On the other hand, in order to estimate the downlink channel based on the uplink channel and reciprocity, the terminal can only transmit to the base station a number of sounding reference signals (SRS) equal to the number of receive antennas of the terminal.

[0198] FIG. 4 is an example comparing a method of estimating a downlink channel based on CSI-RS and a method of estimating a downlink channel based on SRS and reciprocity in a wireless communication system according to an embodiment of the present disclosure.

[0199] Referring to FIG. 4, examples of a method for estimating a downlink channel based on CSI-RS and a method for estimating a downlink channel based on SRS and reciprocity are described. In FIG. 4, it can be assumed that a terminal (400) receives a downlink channel with two receive antennas and a base station (410) transmits a downlink channel with four transmit antennas. If the base station (410) transmits CSI-RSs (421, 422, 423, 424) for each transmit antenna port to the terminal (400), the terminal (400) can measure the downlink channel. Thereafter, the terminal (400) can report channel state information (CSI) of the downlink channel estimated by the received CSI-RSs (421, 422, 423, 424) to the base station (410). On the other hand, if the terminal (400) transmits SRS (431, 432) for each receiving antenna port to the base station (410), the base station (410) can measure the uplink channel. If the base station measures the uplink channel based on the SRS and estimates the downlink channel based on the SRS, the base station can obtain downlink channel information without quantization error of the downlink channel due to CSI feedback. In addition, considering the number of antenna ports of the base station and the terminal, the base station can estimate the downlink channel through a small number of SRS ports compared to the total number of ports of the CSI-RS. If a high-performance base station with a very large number of transmit antenna ports is considered (for example, a base station configured with 32 transmit antenna ports), the advantage of downlink channel estimation based on SRS can be further increased. On the other hand, since the size of the transmit power of the SRS transmitted by the terminal is very small compared to the transmit power of the CSI-RS transmitted by the base station, it may be difficult for the base station to successfully receive the SRS if the distance between the base station and the terminal is very large or sufficient uplink coverage is not sufficiently secured.Alternatively, because the uplink channel estimation error becomes very large, the base station may have difficulty estimating the downlink channel based on the reciprocity of the uplink channel. Despite this drawback, if sufficient uplink channel coverage between the base station and the terminal can be secured, utilizing a method for acquiring downlink channel information based on SRS can be advantageous in that it enables efficient use of RS resources from a system perspective and enables downlink channel acquisition without quantization errors.

[0200] A terminal can support transmission through m antennas and reception through n antennas, such as 'mTnR'. Considering the complexity and cost of the transmit antennas, the number of transmit antennas m of the terminal can be less than or equal to the number of receive antennas n. If the number of transmit antennas m and the number of receive antennas n are the same, a separate antenna switching process for acquiring a downlink channel based on SRS as described above may not be required. The lack of antenna switching can be understood as having an RF chain for uplink transmission implemented on all receive antennas as well as the corresponding antennas. On the other hand, if the number of receive antennas n is greater than the number of transmit antennas m, an antenna switching process may be required to transmit SRS through all n receive antennas as described above. For example, if a terminal is implemented with two transmit antennas and four receive antennas, the terminal needs to be implemented so that the SRS signal is transmitted through a total of four antennas by switching the two transmit antennas once each to transmit the SRS for downlink channel estimation for the four receive antennas.

[0201] Considering the cost and complexity of the terminal, the number of transmit antennas may be smaller than the number of receive antennas of the terminal. For example, receive modules such as receive filters are connected to all receive antenna parts of the terminal, so that downlink signals can be received by n receive antennas. On the other hand, transmit RF chain modules such as transmit filters, low noise amplifiers (LNAs), and power amplifiers (PAs) can be connected to only some transmit antenna parts among all antennas, so that uplink signals can be transmitted by only m transmit antennas. The above-described implementation method may be an implementation that takes into account the heat generation and cost of the terminal, and interference between components. When the terminal supports mTnR and m is less than n, the base station can schedule antenna switching for the terminal to acquire a downlink channel based on SRS as described above.

[0202] FIG. 5 illustrates an example of a case in which a terminal performs SRS antenna switching and a base station acquires a downlink channel when the terminal supports 1T4R in a wireless communication system according to an embodiment of the present disclosure.

[0203] Referring to FIG. 5, an example is described in which a base station acquires a downlink channel by performing SRS antenna switching when a terminal supports 1T4R. The terminal can perform uplink transmission based on one transmit antenna port using one transmit module (e.g., LPAF. LPAF can be composed of an LNA, a PA, and a filter) (500). If the terminal performs antenna switching for four receive antennas (501, 502, 503, 504), the terminal can transmit SRS by sequentially switching one transmit module (500) from the first antenna (501) to the fourth antenna (504) using a switch (505). At this time, the terminal can transmit SRS with a power lower than the power applied to the transmit module due to path loss depending on the form factor of the terminal and the arrangement position of the receive antennas. Transmitting SRS with a power lower than the power applied by the transmission module can be defined as insertion loss (IL). In addition, the terminal may intentionally lower the target power value to prevent interference or interference, depending on reasons such as terminal shape and path loss, as well as the operation of other components of the terminal (e.g., cameras, Bluetooth, Wi-Fi, and other RF components). For example, when performing SRS antenna switching, an imbalance may occur in the SRS transmission power (511, 512, 513, 514) transmitted by each antenna due to not only insertion loss but also interactions between other components of the terminal. As in the example illustrated in FIG. 5, the magnitude of the SRS transmission power (512 to 514) transmitted by the second to fourth antennas may be relatively smaller than the SRS transmission power (511) transmitted by the first antenna.The relatively smaller size of the SRS transmission power transmitted through the second to fourth antennas than the SRS transmission power transmitted through the first antenna can be defined as insertion loss imbalance (IL imbalance). For example, problems may arise where the SRS transmitted through each receiving antenna cannot be transmitted with uniform transmission power due to the terminal's transmission module, antenna arrangement, and interactions between other elements.

[0204] FIG. 6 is a diagram illustrating an example of a terminal structure supporting four receiving antennas in a wireless communication system according to an embodiment of the present disclosure.

[0205] Referring to FIG. 6, unlike the aforementioned FIG. 5, an example of a terminal supporting four receive antennas (601 to 604) may be illustrated. Unlike the transmit module, the receive module (DRX-M, diversity Rx module) (611 to 614) for diversity support is cheaper than the transmit module and can be implemented with a simple structure, so it can be placed and operated on all receive antennas. Accordingly, there may not be a large difference in the insertion loss between each receive antenna (601 to 604) and the receive module (611 to 614), and therefore, unlike the aforementioned case (e.g., FIG. 5), the power imbalance between downlink channels or downlink reference signals such as CSI-RS received by each antenna may be very small or non-existent.

[0206] In addition to the power imbalance (or power imbalance) caused by the Tx-Rx mismatch due to the difference between the RF structures of the transmitter and receiver of the terminal described above, the difference in transmission power between SRS resources may become larger when transmitting SRS resources for antenna switching purposes, as illustrated in FIG. 5, due to other terminal implementation elements. For example, an element for a non-communication function, such as a camera, may be implemented adjacent to a specific antenna path (e.g., the second antenna (502) of FIG. 5) and the RF transmission module (500). When power for uplink transmission is applied to a device such as a camera to an adjacent transmission RF path, RF interference may occur, which may adversely affect the image quality or operation of the camera. For this reason, if a module such as a camera is turned on (or in the 'on' state), the terminal may intentionally lower the amount of power applied to an antenna adjacent to the module such as the camera. For example, the transmission power of uplink signals transmitted through certain antennas may be intentionally reduced to account for mismatches between transmitters and receivers due to the RF structure of the terminal, as well as the impact on modules in other terminals. This may result in multiple SRS resources intended for antenna switching, which would otherwise be transmitted at the same transmission power, being transmitted at different transmission powers.

[0207] As shown in Figures 5 and 6, a difference may occur between the downlink channel estimated based on the SRS transmitted by the terminal and the downlink channel received by the terminal, depending on whether IL imbalance occurs. For example, the base station ideally expects the downlink channel received by the terminal and the downlink channel acquired through SRS antenna switching to be identical. However, due to IL imbalance, an estimation error may occur between the actual downlink channel received by the terminal and the downlink channel estimated by the base station through SRS antenna switching. If the accuracy of the downlink channel estimated by the base station through SRS antenna switching can be improved, the base station can perform accurate precoding on the downlink channel transmitted to the terminal, and the beamforming gain can be maximized through accurate precoding, thereby increasing the downlink throughput.

[0208] <First embodiment: Power headroom reporting trigger method for indicating power imbalance information to a base station>

[0209] In the first embodiment, a terminal may utilize power headroom-based reporting to convey information about power imbalances that occur when transmitting SRS resources for antenna switching purposes to a base station. Here, methods for a terminal to trigger a power headroom report that additionally includes information about power imbalances are described in detail.

[0210] As described above, when transmitting SRS resources for antenna switching purposes, the terminal may transmit the actual SRS resource at a lower power than the SRS transmission power calculated by the schedule information and RRC settings due to power back-off that takes into account the characteristics of the terminal implementation or the impact on other factors. For example, assume that four SRS resources are transmitted in an SRS resource set for 1T4R antenna switching purposes. The terminal can transmit each SRS resource by connecting to four different antennas using a single UL RF chain for uplink transmission. Such SRS for antenna switching purposes can be used to estimate the downlink channel received through the four antennas using the uplink channel and channel reciprocity characteristics estimated from the SRS transmitted by the terminal in a TDD system. As described above, in order to accurately estimate the downlink channel transmitted through the SRS through the SRS, the transceiver of the base station and the transceiver of the terminal may need to be the same (or similar). If the base station can transmit a downlink signal to the base station transmit antenna with the same power and the terminal can receive the downlink signal transmitted by the base station using the terminal receive antenna with the same gain (or similar gain), then in order to estimate the downlink channel using the SRS, the terminal may have to transmit the SRS to the base station with similarly the same (or similar) power and the base station may have to receive the SRS transmitted by the terminal using the base station receive antenna with the same (or similar) gain.Although a base station can receive SRS using a base station receive antenna with the same (or similar) gain, as described above, due to characteristics of the terminal implementation such as power back-off considering the terminal circuit configuration and interference, the terminal may not transmit the SRS at the same (or similar) power. If the terminal transmits an SRS resource for antenna switching at a power different from the transmission power calculated according to scheduling information (e.g., a power transmission parameter indicated by TCI, etc.) and RRC parameters (e.g., a value indicated by the indicated transmission power parameter), the base station may estimate the uplink channel received with the SRS resource having different actual transmission power. Since the base station estimates the uplink channel with the SRS resource transmitted with different actual power rather than the SRS resource transmitted with the same power, the accuracy of the estimated uplink channel decreases, and the accuracy of the downlink channel estimated based on channel reciprocity may also decrease. Mathematical Equation 4 below can represent an uplink channel estimated with an SRS resource transmitted by a terminal with different transmission power.

[0211] [Equation 4]

[0212]

[0213] Here refers to the SRS received by the base station, refers to the four SRS resource signals transmitted by the terminal, means an uplink channel. The four SRS resources transmitted by the terminal are transmitted through different time symbols, and the above mathematical expression 4 can mean a signal received by the base station through all SRS resources transmitted by the terminal. The base station and the terminal are each other. Since the base station knows the received signal Channel information from can be estimated. Ideally, the base station but with different transmission powers, which must be estimated. This means power imbalance because it is transmitted It can be included in the uplink channel information estimated by the base station. For example, it means the power imbalance between SRS resources transmitted by the terminal. The uplink channel estimated by the base station due to The accuracy of the downlink channel estimated by the base station based on channel reciprocity The accuracy may be reduced if the base station experiences power imbalance when the terminal transmits multiple SRS resources for antenna switching purposes. If information about the estimated downlink channel is known, the power imbalance can be compensated for or taken into account. can improve the accuracy of reporting power imbalance. As a method that can be considered for reporting power imbalance, when transmitting SRS resources in the SRS resource set for the corresponding antenna switching purpose, the terminal can report the difference in transmission power between each SRS resource to the base station. Alternatively, when the terminal transmits SRS resources in the SRS resource set for the corresponding antenna switching purpose, the terminal can determine the maximum transmission power for each SRS resource by considering both the power back-off due to the influence of the transmission RF chain and other factors, and can report the determined maximum transmission power to the base station. For example, the terminal can transmit the SRS resource transmitted through the first antenna at a maximum of 23 dBm, but the SRS resource transmitted through the fourth antenna can be transmitted at a maximum of 20 dBm due to insertion loss caused by the path between the antenna and the RF chain. At this time, if the terminal can report to the base station the maximum transmission power of 23 dBm of the SRS resource transmitted through the first antenna, the maximum transmission power of 20 dBm of the SRS resource transmitted through the fourth antenna, and the power actually transmitted for each SRS resource, the base station can take this into consideration and improve the estimation accuracy of the downlink channel.

[0214] A terminal can use a power headroom report (PHR) to report information to a base station to improve the estimation accuracy of a downlink channel. The terminal can trigger a power headroom report when certain conditions are met as described above, and the terminal can transmit a MAC CE for power headroom reporting to the base station by including it in the PUSCH. When the terminal reports power headroom, the maximum transmission power P that the terminal can transmit at the time of transmitting the PUSCH or SRS or at the time of reporting the power headroom CMAX,f,c The terminal may report to the base station the power headroom, which is the difference between the maximum power and the current transmission power (or the power determined based on the reference signal transmission when not actually transmitting an uplink signal). In addition, the terminal may additionally report to the base station the power back-off value to satisfy the maximum permissible emission (MPE) requirement in FR2. In addition, if multiple beams are supported in FR2, the terminal may additionally report to the base station the power back-off values ​​to satisfy the MPE requirement for each candidate beam. If the terminal transmits multiple SRS resources in the SRS resource set for antenna switching to the base station and applies power back-off considering the implementation of the terminal or interference from other elements, resulting in an imbalance in the transmission power between the multiple SRS resources transmitted by the terminal, the terminal may report additional information to the base station using the power headroom report.

[0215] However, if the trigger condition for the power headroom report described above is not met, when the UE transmits an SRS for antenna switching purposes and the eNB estimates the channel based on the SRS, it may not receive additional information that can improve the estimation accuracy. The power headroom trigger condition described above may be when the change in the transmit power of the PUSCH to be transmitted is greater than a certain threshold compared to the previous PHR report, depending on the change in path loss that can be measured through the downlink reference signal, or when an event such as SCell activation or PSCell addition occurs. In particular, the behavior of the UE may be defined so that a temporary power back-off does not trigger a power headroom report or so as not to reflect a power reduction due to a temporary power back-off. If the UE reflects the effect of a temporary power back-off only for PUSCH transmission in the power headroom report, it may be difficult for the eNB to accurately grasp the current transmit power situation of the UE, and therefore the constraints on the UE behavior described above may be defined. However, if the terminal does not report to the base station the impact of power back-off, etc. that occurs when transmitting an SRS resource set for antenna switching purposes as described above, there may be a problem in that the base station cannot identify channel distortion caused by transmission power imbalance between SRS resources during channel estimation. For example, if the terminal transmits multiple SRS resources within an SRS resource set for antenna switching purposes and the actual transmission power of the multiple SRS resources includes an imbalance, a condition that can trigger a separate power headroom report can be added. Accordingly, the terminal can assist the base station in identifying transmission power imbalance between the multiple SRS resources through power headroom reporting, and the base station can improve channel estimation accuracy based on the reported additional information.

[0216] When a terminal transmits a certain SRS, it can trigger a power headroom report and report the power headroom information and additional information for each transmitted SRS resource to the base station. For example, the terminal can transmit multiple SRS resources configured in an SRS resource set of 'antenna switching' usage and trigger a power headroom report to report the power headroom information and additional information about the associated SRS resource set to the base station. The SRS resource set for antenna switching usage can be configured to perform antenna switching for x transmit antennas and y receive antennas, where y > x. In this case, the SRS resource set for 'antenna switching' usage can be configured with a number of SRS resources greater than one. The trigger for the power headroom report associated with the transmission of the SRS resource set for 'antenna switching' usage can operate independently from the trigger event that triggers the power headroom report described above. Alternatively, some trigger events can be reused to trigger the power headroom report associated with the SRS resource set for 'antenna switching' usage.

[0217] If a power headroom report is triggered every time a terminal transmits an SRS resource set for 'antenna switching' purposes (for convenience of explanation, the SRS resource set for antenna switching purposes can be abbreviated as 'SRS AS', hereinafter, SRS AS), the terminal may frequently report power headroom to the base station and waste unnecessary uplink resources. Therefore, in order to limit unnecessary or frequent power headroom reporting, additional information may be checked after the terminal transmits an SRS AS to trigger a power headroom report. The terminal may determine whether to trigger a power headroom report by considering each of the additional information described below or a combination of the additional information. Of course, the additional information is not limited to the examples below.

[0218] Additional Information 1) When transmitting an SRS AS, the UE can determine whether to trigger a power headroom report by considering the scheduled type according to the time domain behavior of the SRS. The time domain behavior of the SRS can be defined as one of 'aperiodic', 'semi-persistent', and 'periodic'. If the UE transmits an SRS AS scheduled with a specific time domain behavior among the three SRS time domain behaviors, the UE can trigger a power headroom report associated with the transmitted SRS AS. For example, if the base station schedules an aperiodic SRS AS to the UE, the UE can transmit the aperiodic SRS AS and trigger a power headroom report associated with it. If the UE transmits a periodic SRS AS scheduled based on the configured RRC parameters, the UE can trigger a power headroom report associated with the periodic SRS AS by considering other additional information.

[0219] Additional Information 2) A new timer may be defined for power headroom reporting associated with SRS AS. Depending on whether the new timer has expired, the UE may trigger power headroom reporting. If the UE has reported to the base station that it can support the power headroom reporting feature associated with SRS AS and the base station uses a technique to improve channel estimation accuracy by using power headroom reporting associated with SRS AS, the base station may configure an RRC parameter to support the technique in the UE. In this case, the base station may configure a prohibit timer as an RRC parameter to prevent the power headroom associated with SRS AS from being triggered unnecessarily in the UE. A time value may be configured in the UE to prohibit the power headroom reporting from being triggered for a certain period of time after the power headroom reporting in the new prohibit timer associated with SRS AS (e.g., phr-ProhibitTimerforCE). The value that can be set to the new prohibit timer (hereinafter, the 'new prohibit timer' may mean phr-ProhibitTimerforCE) may be set to a value representing a certain time (e.g., a value in subframe units). Specifically, candidate values ​​that can be set to the new prohibit timer may be sf0, sf10, sf20, sf50, sf100, sf500, or sf1000. As another example, the value that can be set to the new prohibit timer may be set in units of time, such as ms, or slots, such as sl. The UE may start or restart the new prohibit timer after performing a power headroom report associated with an SRS AS. The new prohibit timer operates until the RRC parameter value that the base station has set for the UE, and the UE may not trigger a power headroom report associated with an SRS AS while the new prohibit timer is operating.If a new prohibit timer expires after a power headroom report associated with an SRS AS for a time period set by an RRC parameter value, the UE may trigger a power headroom report depending on whether other conditions for triggering a power headroom report associated with the SRS AS are met. The new prohibit timer may operate independently from other PHR prohibit timers (e.g., phr-ProhibitTimer). Alternatively, the new prohibit timer may affect whether phr-ProhibitTimer is started or restarted. Whether the two timers are related may be determined based on the information reported through the power headroom report associated with the SRS AS. For example, if the MAC CE format for the power headroom report associated with the SRS AS of the UE only reports the power headroom, maximum transmit power, and additional information to improve channel estimation accuracy for the associated SRS AS, the two timers described above may operate independently. On the other hand, if the MAC CE format for power headroom reporting associated with an SRS AS includes a MAC CE field for reporting the power headroom for the associated SRS AS, the maximum transmit power for the SRS AS, additional information for improving channel estimation accuracy, the power headroom reported through conventional power headroom reporting, the maximum transmit power, and the power back-off value, the two timers described above may operate in conjunction with each other.

[0220] FIG. 7 illustrates an example of a case where two power headroom prohibition timers operate independently in a wireless communication system according to an embodiment of the present disclosure.

[0221] Referring to FIG. 7, an example of a case where two power headroom prohibit timers (700, 701) operate independently is illustrated. A terminal may receive RRC parameters and start a power headroom prohibit timer (700, phr-ProhibitTimer) (702). Independently, the terminal may receive RRC parameters and start a new power headroom prohibit timer (701, phr-ProhibitTimerforCE) that prohibits power headroom associated with an SRS AS (703). The power headroom prohibit timer (700) expires after a predetermined time set by RRC (704), and after the timer (700) expires, the terminal may trigger a power headroom report (706). The new prohibit timer (701) expires after a predetermined time set by RRC (705), and after the timer (701) expires, the terminal may trigger a new power headroom report associated with an SRS AS (707). If a power headroom report is triggered as described above, the terminal can perform a power headroom report (708). At this time, the power headroom report performed by the terminal can be performed independently of the SRS AS transmission. Thereafter, the terminal can restart the prohibit timer (700) for the power headroom report (710), and after a certain period of time and the timer (700) expires (712), the terminal can trigger another power headroom and perform a power headroom report (714). If a new power headroom report associated with the SRS AS is triggered independently of the existing power headroom report being triggered and reported (708), the terminal can perform the new power headroom report (709). Thereafter, the terminal can restart the prohibit timer (701) for the new power headroom report (711), and after a certain period of time and the timer (701) expires (713), the terminal can trigger another new power headroom and perform the new power headroom report (715).

[0222] FIG. 8 illustrates an example of a case in which an existing power headroom prohibition timer operates depending on whether a new power headroom prohibition timer expires in a wireless communication system according to an embodiment of the present disclosure.

[0223] Referring to FIG. 8, an example is shown in which an existing power headroom prohibit timer (800) operates depending on whether a new power headroom prohibit timer (801) expires. Similar to or identical to FIG. 7 described above, the terminal may not trigger power headroom until two prohibit timers (phr-ProhibitTimer, phr-ProhibitTimerforCE) (800, 801) are started (802, 803) and expire. If the two prohibit timers (800, 801) are started (802, 803) and expire after a certain period of time (804, 805), the terminal may trigger a power headroom report or a new power headroom report (806, 807). If a new power headroom report is triggered, the terminal can perform the new power headroom report (809), and while the new power headroom report is triggered and performed (809), the terminal cannot trigger the existing power headroom report (808). After the new power headroom report is performed (809), the terminal can restart both inhibit timers (800, 801) (810, 811). After the terminal restarts both inhibit timers (800, 801) (810, 811) and after a certain period of time (812, 813) when both timers expire, the terminal can trigger the power headroom report or the new power headroom report (814, 815). If the existing power headroom report is triggered and performed (818) during the period in which a power headroom or new power headroom report can be triggered (816, 817), and the existing power headroom prohibit timer (800) is restarted (819), the new power headroom report can be triggered and performed (817). The terminal can restart the power headroom prohibit timer (800) (819) after the existing power headroom report is triggered and performed (818).If a new power headroom report associated with an SRS AS is triggered and performed (820), the UE cannot trigger and perform an existing power headroom report (821) while the new power headroom report is being performed (820). After the UE performs the new power headroom report (820), both inhibit timers (800, 801) can be restarted (822, 823). After the UE restarts both inhibit timers (800, 801) (822, 823) and both timers expire after a certain period of time (824, 825), the UE can trigger either the existing power headroom report or the new power headroom report (826, 827).

[0224] FIG. 9 illustrates an example of a case in which a new power headroom prohibition timer operates depending on whether an existing power headroom prohibition timer has expired in a wireless communication system according to one embodiment of the present disclosure.

[0225] Referring to FIG. 9, an example is shown where a new power headroom prohibit timer (901, phr-ProhibitTimerforCE) operates depending on whether an existing power headroom prohibit timer (900, phr-ProhibitTimer) has expired. The terminal may not trigger power headroom until both prohibit timers (900, 901) have started (902, 903) and expired. If both prohibit timers (900, 901) have started (902, 903) and after a certain period of time (904, 905), the terminal may trigger a power headroom report or a new power headroom report (906, 907). If an existing power headroom report is triggered, the terminal may perform a power headroom report (908), and while a power headroom report is triggered and being performed (908), the terminal cannot trigger a new power headroom report (909). After the existing power headroom report is performed (908), the terminal can restart both inhibit timers (900, 901) (910, 911). After the terminal restarts both inhibit timers (900, 901) (910, 911) and after a certain period of time (912, 913) when both timers expire, the terminal can trigger a power headroom report or a new power headroom report (914, 915). Even if the new power headroom inhibit timer (901) is restarted (919) after the new power headroom report is triggered and performed (918) during the period in which the power headroom or new power headroom can be triggered (916, 917), the existing power headroom report can be triggered and performed (920). After the terminal triggers and performs the new power headroom report (919), the terminal can restart the new power headroom inhibit timer (901) (919).If an existing power headroom report is triggered and performed (920), the terminal cannot trigger and perform a new power headroom report (921) while the existing power headroom report is being performed (920). After the terminal performs the existing power headroom report (920), both inhibit timers (900, 910) can be restarted (922, 923). After the terminal restarts both inhibit timers (900, 901) (922, 923) and both timers expire after a certain period of time (924, 925), the terminal can trigger either the existing power headroom report or the new power headroom report (926, 927).

[0226] The examples of FIGS. 7 to 9 described above illustrate a case where the time (e.g., in subframe units) values ​​set in the RRC parameters of the two prohibit timers are identical. However, the methods described above can be equally applied even when the RRC parameter values ​​set in the two prohibit timers are different.

[0227] Additional Information 3) If a certain condition is met by comparing a certain power value for an SRS AS at the time of calculating the power headroom associated with a previously reported SRS AS with a certain power value for a currently transmitting SRS AS, the terminal can trigger and perform a power headroom report associated with the SRS AS. As a specific example, if the difference between the following transmission power values ​​is greater than a certain threshold, the terminal can trigger a power headroom report associated with the SRS AS. Of course, the present invention is not limited to the following examples.

[0228] - Power Comparison 1) The UE can compare the transmit power difference between the two SRS resources with the largest transmit power difference among the SRS resources within the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS with the transmit power difference between the two SRS resources with the largest transmit power difference among the SRS resources within the currently transmitting SRS AS. If the difference between the two values ​​is greater than or equal to a certain threshold, the UE can trigger and perform power headroom reporting associated with the SRS AS. For example, four SRS resources can be configured within an SRS resource set for the SRS AS, and the UE can switch antennas to transmit the four SRS resources to the base station so that the base station can estimate the downlink channel. If the transmit power difference between any two SRS resources (e.g., the first SRS resource and the fourth SRS resource) within the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS is greater than the transmit power difference between any two other SRS resources, and the value is assumed to be 3 dB. If the difference in transmission power between any two SRS resources (e.g., the first SRS resource and the fourth SRS resource) among the SRS resources to be transmitted by the current terminal in the SRS AS is greater than the difference in transmission power between any other two SRS resources, and the value is assumed to be 9 dB,If a threshold (e.g., phr-Tx-PowerFactorChangeforSRS) is set to 'dB3' according to power comparison 1, the difference in transmission power according to power comparison 1 becomes greater than 3 dB, which is the threshold set, because the difference in power between SRS resources at the time of reporting power headroom associated with the previous SRS AS is 3 dB, which is the maximum difference in power between SRS resources in the current transmitting SRS AS, which is 9 dB, which is a difference of 6 dB. Therefore, the terminal can trigger and perform power headroom reporting associated with the new SRS AS.

[0229] - Power comparison 2) The UE can compare the transmit power value of the SRS resource with the lowest transmit power among the SRS resources in the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS with the transmit power value of the SRS resource with the lowest transmit power among the SRS resources in the currently transmitting SRS AS. If the difference between the two values ​​is greater than or equal to a certain threshold, the UE can trigger and perform power headroom reporting associated with the SRS AS. For example, it is assumed that the transmit power of any one of the four SRS resources in the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS (for example, the fourth SRS resource) is the lowest, and its value is 20 dBm. It is also assumed that the transmit power of any one of the four SRS resources in the SRS AS to which the UE will currently transmit (for example, the fourth SRS resource) is the lowest, and its value is 16 dBm. If a threshold (e.g., phr-Tx-PowerFactorChangeforSRS) is set to 'dB3' according to power comparison 2, the UE can trigger and perform power headroom reporting associated with a new SRS AS because the difference between the transmit power of the SRS resource with the lowest transmit power at the time of reporting power headroom associated with the previous SRS AS and the transmit power of the SRS resource with the lowest transmit power in the current transmitting SRS AS is 4 dB, which is greater than the 3 dB set as the threshold.

[0230] - Power comparison 3) The UE can compare the transmit power value of the SRS resource with the highest transmit power among the SRS resources in the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS with the transmit power value of the SRS resource with the highest full-rate power among the SRS resources in the currently transmitting SRS AS. If the difference between the two values ​​is greater than or equal to a certain threshold, the UE can trigger and perform power headroom reporting associated with the SRS AS. For example, it is assumed that the transmit power of any one of the four SRS resources in the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS (for example, the first SRS resource) is the highest, and its value is 23 dBm. It is also assumed that the transmit power of any one of the SRS resources in the SRS AS to which the UE will currently transmit (for example, the first SRS resource) is the highest, and its value is 20 dBm. If a threshold (e.g., phr-Tx-PowerFactorChangeforSRS) is set to 'dB3' according to power comparison 3, the UE can trigger and perform power headroom reporting associated with a new SRS AS because the difference between the transmit power of the SRS resource with the highest transmit power at the time of reporting power headroom associated with the previous SRS AS and the transmit power of the SRS resource with the highest transmit power in the current transmitting SRS AS is 3 dB, which is the same as the 3 dB set as the threshold.

[0231] In the power comparison 1 to power comparison 3 described above, the power comparison was made between the SRS AS at the time of calculating the power headroom associated with the SRS AS to be currently transmitted and the SRS AS previously reported, but the method described above may be extended to the SRS AS at the time of calculating any power headroom reported before the base station reports additional information that can improve the channel estimation accuracy.

[0232] Additional Information 4) If a combination of two SRS resources having the largest (or smallest) transmit power difference among SRS resources within the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS and two SRS resources within the currently transmitting SRS AS having the largest (or smallest) transmit power difference is changed, the UE may trigger and perform a new power headroom report associated with the SRS AS. For example, if a combination of two SRS resources (e.g., the first SRS resource and the fourth SRS resource) within the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS and a combination of two SRS resources (e.g., the first SRS resource and the second SRS resource) within the currently transmitting SRS AS having the largest (or smallest) transmit power difference are different, the UE may trigger and perform a new power headroom report associated with the SRS AS.

[0233] In Additional Information 4, we compared the change of the two SRS resource combinations with the largest (or smallest) difference in transmit power within the SRS AS at the time of calculating the power headroom associated with the currently transmitting SRS AS and the previously reported SRS AS, but it may also be extended to the SRS AS at the time of calculating any power headroom reported before the base station reports the additional information that can improve the channel estimation accuracy, to determine whether to trigger power headroom reporting according to Additional Information 4.

[0234] Additional Information 5) If the relationship between the transmit power of SRS resources within the SRS AS currently transmitting changes compared to the relationship between the transmit power of SRS resources within the SRS AS at the time of calculating the power headroom associated with the previously reported SRS AS, the terminal can trigger and perform a new power headroom report associated with the SRS AS. For example, if the transmission power of SRS resources within an SRS AS at a time of calculating power headroom associated with a previously reported SRS AS has a certain magnitude relationship (e.g., the magnitude of transmission power decreases in the order of first SRS resource > second SRS resource > third SRS resource > fourth SRS resource), and the transmission power of SRS resources within an SRS AS to be currently transmitted has a different magnitude relationship (e.g., the magnitude of transmission power decreases in the order of second SRS resource > first SRS resource > fourth SRS resource > third SRS resource), the UE may determine that the magnitude relationship of the transmission power of SRS resources within the SRS AS at two different times has changed and may trigger and perform a new power headroom report associated with the SRS AS.

[0235] In Additional Information 5, the relationship between the size of the SRS AS SRS resources at the time of calculating the power headroom associated with the SRS AS to be currently transmitted and the previously reported SRS AS is compared, but whether or not to trigger power headroom reporting according to Additional Information 5 may be determined by extending to the SRS AS at the time of calculating any power headroom reported before the base station reports the additional information that can improve channel estimation accuracy.

[0236] Additional Information 6) If the base station transmits an SRS resource to perform switching for all antennas according to the xTyR configuration configured in the terminal among the antenna switching configurations that the terminal can support, the terminal can determine whether to trigger a power headroom report. For example, if the terminal supports 1T4R, the terminal may have to transmit SRS using 1Tx antenna for up to four Rx antennas, so a total of four SRS resources may have to be transmitted using different Rx antennas. If the terminal has transmitted all four SRS resources to perform antenna switching and determines that power headroom reporting is necessary based on the additional information(s) described above, the terminal may trigger a power headroom report. On the other hand, if the terminal has transmitted only some of the four SRS resources to perform antenna switching, the terminal may not trigger a power headroom report even if it determines that power headroom reporting is necessary based on the additional information(s) described above. In this case, the terminal may trigger a power headroom report after transmitting the remaining SRS resources that were not transmitted.

[0237] <Second embodiment: Method for configuring a MAC CE format for power headroom reporting including power imbalance information>

[0238] In the second embodiment, a MAC CE format transmitted by a terminal to a base station to perform power headroom including power imbalance information is specifically described.

[0239] As described above, if a terminal triggers a power headroom report to report power imbalance information to a base station, the terminal can transmit a MAC CE for power headroom reporting to the base station using the PUSCH. Since power imbalance information is a new type of information, it may be difficult for the terminal to report the power imbalance information to the base station if the MAC CE format illustrated in FIG. 1 or FIG. 2 is used. A new MAC CE format may be required for the terminal to report power imbalance information to the base station via a power headroom report. Therefore, a new MAC CE format for power headroom reporting that includes power imbalance information can be defined, as described below.

[0240] A terminal may additionally configure a MAC CE field to report power imbalance information in the MAC CE format for single entry power headroom reporting.

[0241] Single Entry Power Headroom Configuration 1) In addition to the power headroom information for the PUSCH transmitting the MAC CE for single entry power headroom reporting, power imbalance information may be added for the maximum transmit power for each SRS resource of the SRS AS associated with the MAC CE.

[0242] FIG. 10 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting maximum transmission power for each SRS resource of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0243] Referring to Figure 10, an example of a single entry power headroom MAC CE format that can additionally report the maximum transmit power for each SRS resource of an SRS AS is shown. The example P field and PH field and MPE (or DPC or R) field and P CMAX,f,cThe field may be identical to the field of the same name described in [Table 4] in 'PHR related'. The C field (1001) may indicate whether a field (1002) for reporting the maximum transmission power for each SRS resource of the SRS AS to be described later exists. For example, if the C field (1001) is set to 1, a field (1002) for reporting the maximum transmission power for each SRS resource of the SRS AS to be described later may exist. If the C field (1001) is set to 0, a field (1002) for reporting the maximum transmission power for each SRS resource of the SRS AS to be described later may not exist. If the C field (1001) is set to 1 and there is a field (1002) for reporting the maximum transmission power for each SRS resource of the SRS AS, the UE can determine the number of the corresponding fields (1002) according to xTyR set by the base station to the UE based on the UE capability report of the UE. For example, the UE can set and report to the base station y / x fields (1002) in order to report the maximum transmission power for y / x SRS resources. For example, if the base station sets one SRS resource set whose resourceType is 'aperiodic' and whose purpose is 'antennaSwitching' for a UE that supports 1T4R antenna switching (e.g., a terminal implemented with 1 Tx chain and 4 Rx chains), the base station can set four SRS resources within the SRS resource set whose purpose is 'antennaSwitching', and the UE can configure the field (1002) for reporting the maximum transmission power for the four SRS resources.Alternatively, if the base station configures two SRS resource sets for the terminal, each of which has a resourceType of 'aperiodic' and a purpose of 'antennaSwitching', the base station may configure each SRS resource set to include two SRS resources, so that a total of four SRS resources are included in the two SRS resource sets. Thereafter, the terminal may configure a field (1002) for reporting the maximum transmission power for the four SRS resources included in the two SRS resource sets. If the terminal has transmitted only some of the two SRS resource sets and triggers a power headroom report to report power imbalance information to the base station, the terminal may calculate the expected maximum transmission power based on the current status of the terminal for the untransmitted SRS resources and determine the value of the field (1002) for reporting the maximum transmission power. Alternatively, the terminal may not configure the field (1002) for the untransmitted SRS resources or may report a dummy value. The terminal may configure the field (1002) for the transmitted SRS resources and report it to the base station. The example illustrated in Fig. 10 is only an example, and the same or similar application can be applied to xTyR of other settings than 1T4R to configure the MAC CE format for the terminal to additionally report the maximum transmission power of each SRS resource.

[0244] In addition to the fields described above, the terminal may also add information about the SRS AS to which the power headroom report is associated. As in the second MAC CE format (1010) of FIG. 10, at least one field may be additionally configured among a field (1011) for indicating a serving cell in which the SRS AS to which the power headroom report is associated is configured, a field (1012) for indicating a BWP within the serving cell in which the SRS AS is configured, and a field (1013) for indicating an SRS Resource Set Id of the SRS AS. The terminal may also configure the MAC CE by including a field for indicating the SRS AS to which the power headroom report is associated in other examples described below.

[0245] In FIG. 10, the first MAC CE format (1000) may include a field (1002) for reporting the maximum transmit power for each SRS resource of the SRS AS.

[0246] Single Entry Power Headroom Configuration 2) In addition to the power headroom information for the PUSCH transmitting the corresponding MAC CE, the difference between the maximum transmit power of the SRS resource that can be transmitted with the highest maximum transmit power among the SRS resources within the SRS AS associated with the corresponding MAC CE and the maximum transmit power of each SRS resource can be added as power imbalance information.

[0247] FIG. 11 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting a difference value between the maximum transmit power for each SRS resource of an SRS AS and the largest maximum transmit power among the maximum transmit powers of SRS resources within the SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0248] Referring to Figure 11, an example of a single entry power headroom MAC CE format that can additionally report the difference between the maximum transmit power for each SRS resource of an SRS AS and the largest maximum transmit power among the maximum transmit powers of SRS resources within the SRS AS is shown. The example P field and the PH field and the MPE (or DPC or R) field and the P CMAX,f,cThe field may be the same as the field of the same name described in [Table 4] in 'PHR related'. The C field (1101) may indicate whether a field (1102) for reporting a difference value between the maximum transmit power of each SRS resource and the largest maximum transmit power among the maximum transmit powers of the SRS resources within the SRS AS exists. For example, if the C field (1101) is set to 1, a field (1102) for reporting a difference value between the maximum transmit power of each SRS resource described later and the largest maximum transmit power among the maximum transmit powers of the SRS resources within the SRS AS may exist. If the C field (1101) is set to 0, a field (1102) for reporting a difference value between the maximum transmit power of each SRS resource described later and the largest maximum transmit power among the maximum transmit powers of the SRS resources within the SRS AS may not exist. If the C field (1101) is set to 1 and there is a field (1102) for reporting the difference between the maximum transmit power of each SRS resource and the largest maximum transmit power among the maximum transmit powers of SRS resources within the SRS AS, the terminal can determine the number of the fields (1102) according to xTyR set to the terminal by the base station based on the UE capability report of the terminal. For example, the terminal can set y / x fields (1102) and report to the base station in order to report the difference between the maximum transmit power of y / x SRS resources and the largest maximum transmit power among the maximum transmit powers of y / x SRS resources. Alternatively, the terminal can indicate the SRS resource with the largest calculated maximum transmit power among the y / x SRS resources by using some of the R fields in the MAC CE, and can set y / x - 1 fields (1102) and report to the base station.For example, if a base station configures an SRS resource set whose resourceType is 'aperiodic' and whose purpose is 'antennaSwitching' for a terminal that supports 2T4R antenna switching (e.g., a terminal implemented with two Tx chains and four Rx chains), the terminal may configure a field (1102) to report a difference value between the maximum transmit power of two SRS resources in the SRS resource set whose purpose is 'antennaSwitching' and the largest transmit power among the maximum transmit powers of the two SRS resources. Alternatively, if the base station configures two SRS resource sets whose resourceType is 'aperiodic' and whose purpose is 'antennaSwitching' for the terminal, the base station may configure each SRS resource set to include one SRS resource. In addition, the terminal may configure a field (1102) to report a difference value between the maximum transmit power of a total of two SRS resources and the largest maximum transmit power among the maximum transmit powers of the two SRS resources. If the UE transmits only a part of the two SRS resource sets and triggers a power headroom report to report power imbalance information to the base station, the UE can calculate the expected maximum transmit power based on the current UE status for the untransmitted SRS resources and determine the highest maximum transmit power. In addition, the UE can determine the value of the field (1102) for reporting the difference value between the maximum transmit power of each SRS resource and the highest maximum transmit power. Alternatively, the UE may not configure the field (1102) for the untransmitted SRS resources or may report a dummy value.At this time, the terminal can report the difference value between the maximum transmission power of the transmitted SRS resource and the maximum transmission power of each transmitted SRS resource in the corresponding field (1102). The example illustrated in Fig. 11 is only an example, and a MAC CE format for the terminal to report power headroom can be configured by applying the same or similar method to xTyR of a setting other than 2T4R.

[0249] In addition to the fields described above, the terminal may also add information about the SRS AS to which the power headroom report is associated. As in the second MAC CE format (1110) of FIG. 11, at least one field may be additionally configured among a field (1111) for indicating a serving cell in which the SRS AS to which the power headroom report is associated is configured, a field (1112) for indicating a BWP within the serving cell in which the SRS AS is configured, and a field (1113) for indicating an SRS Resource Set Id of the SRS AS.

[0250] In Fig. 11, the field (1102) for reporting the difference value between the maximum transmission power of each SRS resource in the SRS AS and the largest maximum transmission power among the maximum transmission powers of the SRS resources in the SRS AS is configured with 6 bits, but it may also be configured with bits smaller than 6 bits (e.g., 4 bits) or larger than 6 bits.

[0251] Single Entry Power Headroom Configuration3) In addition to the power headroom information for the PUSCH transmitting the MAC CE for single entry power headroom reporting, the power headroom for the SRS resource within the SRS AS associated with the MAC CE can be added as power imbalance information.

[0252] FIG. 12 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting power headroom for each SRS resource of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0253] Referring to Figure 12, an example of a single entry power headroom MAC CE format that can additionally report power headroom for each SRS resource of an SRS AS is shown. The example P field and PH field and MPE (or DPC or R) field and P CMAX,f,cThe field may be the same as the field of the same name described in [Table 4] in 'PHR related'. The C field (1201) may indicate whether a field (1202) for reporting the power headroom for each SRS resource of the SRS AS described later exists. For example, if the C field (1201) is set to 1, a field (1202) for reporting the power headroom for each SRS resource of the SRS AS may exist. If the C field (1201) is set to 0, a field (1202) for reporting the power headroom for each SRS resource of the SRS AS may not exist. If the C field (1201) is set to 1 and a field (1202) for reporting the power headroom for each SRS resource of the SRS AS exists, the UE may determine the number of the corresponding field (1202) according to the xTyR set to the UE by the base station based on the UE capability report of the UE. For example, a terminal can configure y / x fields (1202) to report power headroom for y / x SRS resources to the base station. For example, if a terminal supporting 2T6R antenna switching (e.g., a terminal implemented with 2 Tx chains and 6 Rx chains) configures three SRS resource sets with resourceType of 'aperiodic' and purpose of 'antennaSwitching', the base station can configure each SRS resource set to include one SRS resource. In addition, the terminal can configure a field (1202) to report power headroom for a total of three SRS resources included in the three SRS resource sets.If the terminal transmits only some of the two SRS resource sets and triggers power headroom reporting to report power imbalance information to the base station, the terminal may calculate the expected maximum transmission power for the untransmitted SRS resources based on the current status of the terminal and determine the value of the field (1202) for reporting the power headroom of the untransmitted SRS resources. Alternatively, the terminal may not configure the field (1202) for the untransmitted SRS resources or may report a dummy value. The terminal may configure the field (1202) for the transmitted SRS resources and report it to the base station. The example illustrated in FIG. 12 is only an example, and the MAC CE format for the terminal to report the power headroom may be configured in the same or similar manner for xTyR of a setting other than 2T6R.

[0254] In addition to the fields described above, the terminal may also add information about the SRS AS to which the power headroom report is associated. As in the second MAC CE format (1210) of FIG. 12, at least one field may be additionally configured among a field (1211) for indicating a serving cell in which the SRS AS to which the power headroom report is associated is configured, a field (1212) for indicating a BWP within the serving cell in which the SRS AS is configured, and a field (1213) for indicating an SRS Resource Set Id of the SRS AS.

[0255] Single Entry Power Headroom Configuration4) In addition to power headroom information for the PUSCH transmitting the MAC CE for single entry power headroom reporting, power imbalance information of SRS resources within the SRS AS associated with the MAC CE may be added.

[0256] FIG. 13 illustrates an example of a single entry power headroom MAC CE format capable of additionally reporting power imbalance information of SRS resources of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0257] Referring to Figure 13, an example of a single entry power headroom MAC CE format that can additionally report power imbalance information of SRS resources of an SRS AS is shown. The example P field and PH field and MPE (or DPC or R) field and P CMAX,f,cThe field may be identical to the field of the same name described in [Table 4] in 'PHR related'. The C field (1301) may indicate whether a field (1302) for reporting implicit or explicit information on the power imbalance relationship and ratio of SRS resources within the SRS AS, which will be described later, exists. For example, if the C field (1301) is set to 1, a field (1302) for power imbalance information may exist. In addition, if the C field (1301) is set to 0, a field (1302) for power imbalance information may not exist. If the C field (1301) is set to 1 and a field (1302) for reporting power imbalance information of SRS resources within the SRS AS exists, the number of bits of the field (1302) and the information signified by each code point may be determined by the base station according to xTyR set to the UE based on the UE capability report of the UE. For example, the number of bits in the field (1302) and the information that each code point signifies can be determined according to the power imbalance between y / x SRS resources, and the larger the number of y / x, the more bits and code points may be required. For example, if the terminal supports 1T8R, 8 bits may be required to indicate the power imbalance relationship between 8 SRS resources, and a total of 256 code points can directly or indirectly indicate the degree of power imbalance between the 8 SRS resources. If the terminal supports 1T2R, 3 bits less than 8 bits may be required to indicate the power imbalance relationship between 2 SRS resources, and a total of 8 code points can directly or indirectly indicate the degree of power imbalance between the 2 SRS resources.As a specific example, the first code point ('000') among the eight code points may mean that the maximum transmit power between the two SRS resources is the same. The second code point ('001') among the eight code points may mean that the maximum transmit power of the second SRS resource (the SRS resource with a larger SRS-ResourceId among the two SRS resources) among the two SRS resources is 3 dB lower than the maximum transmit power of the first SRS resource (the SRS resource with a smaller SRS-ResourceId among the two SRS resources). The third code point ('010') among the eight code points may mean that the maximum transmit power of the first SRS resource (the SRS resource with a smaller SRS-ResourceId among the two SRS resources) among the two SRS resources is 3 dB lower than the maximum transmit power of the second SRS resource (the SRS resource with a larger SRS-ResourceId among the two SRS resources). Similarly, each code point can indicate information that can directly or indirectly indicate the magnitude relationship between the maximum transmit power between SRS resources.

[0258] In addition to the fields described above, the terminal may also add information about the SRS AS to which the power headroom report is associated. As in the second MAC CE format (1310) of FIG. 13, at least one field may be additionally configured among a field (1311) for indicating a serving cell in which the SRS AS to which the power headroom report is associated is configured, a field (1312) for indicating a BWP within the serving cell in which the SRS AS is configured, and a field (1313) for indicating an SRS Resource Set Id of the SRS AS.

[0259] The single entry power headroom configurations 1 to 4 described above exemplify various MAC CE formats for additionally reporting power imbalance information in addition to power headroom information for a PUSCH transmitting a MAC CE for single entry power headroom reporting. However, when a terminal triggers power headroom to report power imbalance information occurring when transmitting an SRS AS to a base station, the terminal may report to the base station the power headroom information and power imbalance information for the SRS AS associated with the power headroom report, rather than the power headroom information for the PUSCH transmitting the MAC CE. For example, the PH field illustrated in FIGS. 10 to 13 is used to report power headroom information for a PUSCH transmitting a corresponding MAC CE, but as illustrated in FIG. 14, the terminal reports an average power headroom value for an SRS AS to which the corresponding power headroom report is associated (e.g., an average value of power headroom values ​​of each SRS resource, a minimum value among power headrooms of the SRS resource, or a maximum value among power headrooms of the SRS resource) as the PH field and reports the largest value (or average value or smallest value) among the maximum transmission powers of the SRS resources in the SRS AS as the P CMAX,f,c You can report it to the field.

[0260] FIG. 14 illustrates examples of a single entry power headroom MAC CE format capable of reporting power headroom and maximum transmit power and power imbalance information of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0261] Referring to FIG. 14, it is assumed that the terminal supports 1T4R, and the terminal can report to the base station fields (1402, 1412, 1422, 1432) for reporting power imbalance information in a manner identical to or similar to that described above in single entry power headroom configuration 1 to single entry power headroom configuration 4.

[0262] As another example, a terminal may report power headroom information for a PUSCH transmitting a MAC CE for a single entry power headroom report, power headroom information for the SRS AS to which the power headroom report is associated, and power imbalance information all in the MAC CE.

[0263] FIG. 15 illustrates examples of a single entry power headroom MAC CE format that can report power headroom of a PUSCH transmitting MAC CE and power headroom and power imbalance information of an SRS AS together in a wireless communication system according to an embodiment of the present disclosure.

[0264] Referring to FIG. 15, the terminal includes a power headroom value for a PUSCH including a power headroom report and a maximum transmission power when transmitting a PUSCH in the first PH field and the first P CMAX,f,c In addition, the terminal may report the average power headroom value for the SRS AS associated with the power headroom report (e.g., the average of the power headroom values ​​of each SRS resource, the minimum power headroom of the SRS resource, or the maximum power headroom of the SRS resource) as the second PH field, and the largest value (or the average value or the smallest value) among the maximum transmit powers of the SRS resources within the SRS AS as the second P CMAX,f,ccan be reported as fields. The first P field and the second P field can be set to 0 or 1 depending on whether P-MPR is applied or its value or DPC (delta power class) is applied when transmitting PUSCH or SRS AS, respectively. In Fig. 15, it is assumed that the terminal supports 1T4R, and the terminal can configure fields (1502, 1512, 1522, 1532) for reporting power imbalance information to the base station in the same or similar manner as described above in Single Entry Power Headroom Configuration 1 to Single Entry Power Headroom Configuration 4. Alternatively, one of the first or second P fields can be omitted and reserved as an R field, and the MPE or DPC field associated with the omitted P field (for example, if the first P field is omitted, the first MPE or DPC field) is omitted and the P configured in the same octet as the omitted field. CMAX,f,c Fields may also be omitted. For example, the octets that constitute an omitted MPE or DPC field may be omitted. And P CMAX,f,c The octets that make up a field may be omitted.

[0265] In the above-described MAC CE format example, the number of fields for reporting power imbalance information may be determined by the base station with reference to the xTyR antenna switching configuration configured in the terminal. However, the number of fields for reporting power imbalance information included in the MAC CE format may also be determined according to the value set in a certain RRC parameter configured by the base station. For example, if the base station sets the RRC parameter called NrofImbalanceInfo to '2' in the terminal, the terminal may configure up to two fields for reporting power imbalance information in the MAC CE format. Here, the value that can be set in NrofImbalanceInfo may be less than or equal to the value of y / x. Alternatively, only a specific number of power imbalance information may be reported according to rules defined in advance by the base station and the terminal. For example, only the largest value or the smallest value may be reported as power imbalance information.

[0266] The terminal may additionally configure a MAC CE field for additionally reporting power imbalance information in the MAC CE format for multiple entry power headroom reporting. The above-described example may include a method for configuring a MAC CE format for single entry power headroom reporting. However, if multiple entry power headroom reporting is supported, the terminal may configure the field for reporting power imbalance information in the MAC CE format for multiple entry power headroom reporting together with or separately from the power headroom field and the maximum transmit power field of the serving cell to which the terminal wishes to report.

[0267] FIG. 16 illustrates an example of a multi-entry power headroom MAC CE format capable of additionally reporting maximum transmission power for each SRS resource of an SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0268] Referring to FIG. 16, an example of a multi-entry power headroom MAC CE format capable of additionally reporting the maximum transmit power for each SRS resource of an SRS AS is shown. Similar to the MAC CE format for single-entry power headroom reporting, the MAC CE format according to the embodiment of the present disclosure includes an I field for indicating whether a field exists for reporting the maximum transmit power for each SRS resource of an SRS AS as power imbalance information for each serving cell. C The field (1601) may be added as many times as the number of serving cells. For example, if the I0 field (1601) is set to 1, a field (1602) may be configured to report the maximum transmission power for each SRS resource of the SRS AS for the PCell. At this time, the number of the corresponding fields (1602) may be determined based on the antenna switching xTyR setting configured for the corresponding serving cell. On the other hand, if the I2 field (1601) is set to 0, a field for reporting the maximum transmission power for each SRS resource of the SRS AS for the serving cell 2 may not be configured. Although the case of reporting the maximum transmission power for each SRS resource with power imbalance information is described in FIG. 16, a multi-entry power headroom may be configured by including fields for reporting various types of power imbalance information as described in Single Entry Power Headroom Configuration 1 to Single Entry Power Headroom Configuration 4.

[0269] <Third embodiment: PUSCH transmission method for transmitting a power headroom report including power imbalance information>

[0270] In the third embodiment, a method for a terminal to transmit a PUSCH for transmitting a MAC CE for power headroom reporting to a base station when an SRS resource of an SRS resource set for antenna switching purposes is transmitted and a power headroom report including power imbalance information is triggered is specifically described.

[0271] The terminal can transmit an SRS AS scheduled by the base station. If a power headroom report associated with the aforementioned SRS AS is triggered, the terminal can configure a MAC CE format for the power headroom report, including power imbalance information, and transmit it on the PUSCH. The PUSCH to be transmitted by the terminal can be determined using the following method. Of course, the present invention is not limited to the following examples.

[0272] PUSCH scheduling method 1) If an Aperiodic (AP) SRS AS is scheduled and transmitted and a power headroom report associated with the AP SRS AS is triggered, the base station can transmit scheduling information of a PUSCH for transmitting the power headroom MAC CE to the UE through a DCI (e.g., DCI format 0_1 ​​or DCI format 0_2 or DCI format 0_3) for scheduling the associated AP SRS AS. For example, an SRS request field for scheduling an AP SRS AS and scheduling information of a PUSCH for transmitting a MAC CE for power headroom reporting including power imbalance information of an SRS AS scheduled by the corresponding DCI can be indicated by the same DCI. The transmission timing of the associated SRS AS triggered by the same DCI as the transmission timing of the PUSCH for reporting the power headroom associated with the SRS AS can be determined according to any rule. For example, a PUSCH for reporting power headroom associated with an SRS AS can be transmitted a certain period of time (e.g., Offset 1) after the associated SRS AS is transmitted. In this case, the certain period of time may refer to the time required for the UE to generate and encode information for power headroom reporting and prepare to transmit MAC CE on the PUSCH after the SRS AS is transmitted. In addition, the UE may notify the base station of the above-described certain period of time through the UE capability report, and the base station may determine that the UE can report power headroom a certain period of time after transmitting the SRS AS based on the UE capability report notified by the UE. The UE may refer to the TDRA (time domain resource assignment) in the DCI that schedules the SRS AS and the PUSCH to determine the time domain resources of the PUSCH for reporting the power headroom MAC CE associated with the SRS AS.The terminal may refer to the TDRA field indicated by the DCI scheduling the PUSCH to determine the slot in which the PUSCH is transmitted. In addition, the terminal may define differently the reference slot to which the K2 value indicated by the TDRA field is applied. The terminal may refer to the TDRA field indicated by the DCI scheduling the PUSCH to determine the slot in which the PUSCH is transmitted. In addition, the terminal may apply the K2 value indicated by the TDRA field based on the slot n in which the DCI is received, so that n + K2 (for example, assuming that the SCS of the serving cell receiving the DCI and the SCS of the serving cell transmitting the PUSCH are the same). In this case, the base station may need to determine the K2 value indicated by the TDRA field so that the terminal can transmit the PUSCH a certain time after the slot in which the SRS AS associated with the power headroom report is transmitted. Alternatively, the terminal may refer to the TDRA field indicated by the DCI scheduling the PUSCH to determine the slot in which the PUSCH is transmitted. In addition, the terminal may apply the K2 value indicated by the TDRA field based on the slot in which the SRS AS is transmitted, and transmit the PUSCH after the K2 slot based on the (t+1)-th available slot (e.g., flexible symbols or UL symbols capable of transmitting all SRS resources of the SRS resource set) from the n + k (e.g., slotOffset set in the triggered SRS AS) (for example, assuming that the terminal supports the terminal capability to determine available slot-based SRS transmission resources and has received RRC configuration from the base station to support available slot-based operation, and that the SCS of the serving cell receiving the DCI is the same as the SCS of the serving cell transmitting the PUSCH).In order to support the operation of applying the K2 value indicated by the TDRA field based on the slot in which the SRS AS is transmitted as described above, the terminal must support power headroom reporting associated with the SRS AS, and the base station may configure a new RRC parameter to support power headroom reporting associated with the SRS AS in the terminal. If the terminal receives a new RRC parameter to support power headroom reporting associated with the SRS AS from the base station, the terminal may apply the K2 value indicated by the TDRA field based on the slot in which the SRS AS is transmitted as described above. The terminal may check a new RRC parameter to support power headroom reporting associated with the SRS AS in order to determine whether to apply the K2 value indicated by the TDRA field based on the slot in which the SRS AS is transmitted as described above. In addition, the terminal may check whether the SRS AS to which the corresponding RRC parameter is associated is triggered. For example, a new RRC parameter may be configured in a certain SRS resource set for antenna switching purposes. If the UE receives a DCI that triggers an SRS AS with some new RRC parameters set to support power headroom reporting associated with the SRS AS, the UE may apply the K2 value indicated by the TDRA field as described above based on the slot in which the SRS AS is transmitted to determine the transmission timing of the PUSCH scheduled with the same DCI.

[0273] Alternatively, if an AP SRS AS is scheduled and transmitted and a power headroom report associated with the AP SRS AS is triggered, the UE may complete transmission of all SRS resources within the AP SRS AS and transmit a MAC CE for power headroom report to the base station using the fastest scheduled PUSCH (for example, any PUSCH among DCI-based DG PUSCH or RRC-based CG PUSCH can be used) after a certain period of time. In this case, the period of time may be notified by the UE to the base station through the UE capability report as described above, and the base station may configure a certain RRC parameter or schedule the PUSCH considering the period of time reported through the UE capability. Alternatively, the base station and the UE may recognize in advance that a certain specific time will be defined in advance to transmit the SRS AS and that a power headroom report can be transmitted through the PUSCH after the certain time.

[0274] FIG. 17 illustrates a method for determining a transmission time of a PUSCH for performing power headroom reporting of an AP SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0275] The UE may receive DCI (1700) scheduling AP SRS AS (1701). If the UE triggers a power headroom report associated with the AP SRS AS (1701), the UE may determine a slot for transmitting a PUSCH (1702) by applying K2 (1704) indicated by the TDRA field in the DCI (1700) to slot n in which the DCI (1700) is received. At this time, the UE may need to transmit the PUSCH (1702) after a certain time Offset1 (1703) from the time at which all AP SRS ASs (1701) are transmitted. If the AP SRS AS (1701) means multiple SRS resource sets for antenna switching purposes, the UE may use the time at which all SRS resources for performing xTyR antenna switching are transmitted as a reference.

[0276] FIG. 18 illustrates another method for determining a transmission time of a PUSCH for performing power headroom reporting of an AP SRS AS in a wireless communication system according to an embodiment of the present disclosure.

[0277] The UE may receive DCI (1800) scheduling the AP SRS AS (1801). If the UE triggers a power headroom report associated with the AP SRS AS (1801), the UE may determine a slot for transmitting the PUSCH (1802) by applying K2 (1804) indicated by the TDRA field in the DCI (1800) to slot m in which all AP SRS CSs (1801) have been transmitted. At this time, the UE may need to transmit the PUSCH (1802) after a certain time Offset1 (1803) from the time at which all AP SRS ASs (1801) have been transmitted. If the AP SRS AS (1801) means multiple SRS resource sets for antenna switching purposes, the UE may use the time at which all SRS resources for performing xTyR antenna switching have been transmitted as a reference.

[0278] PUSCH scheduling method 2) If a semi-persistent (SP) SRS AS is activated with MAC CE and transmits at a period configured by RRC, and a power headroom report associated with the SP SRS AS is triggered, the base station may configure the RRC parameters of the Configured grant (CG) type 1 PUSCH or CG type 2 PUSCH for transmitting the power headroom MAC CE to the UE and activate the CG type 2 PUSCH. The base station may configure the RRC parameters (e.g., periodicity in ConfiguredGrantConfig and periodicityAndOffset-sp in SRS-Resource) to the UE so that the CG type 1 PUSCH or CG type 2 PUSCH, through which power headroom for the SP SRS AS is transmitted, can be transmitted at the same period as the associated SP SRS AS. The base station may set timeDomainOffset for the terminal to transmit CG type 1 PUSCH or CG type 2 PUSCH, in which power headroom for the SP SRS AS is transmitted, a predetermined time after the terminal has transmitted all SRS resources within the SP SRS AS (when performing power headroom reporting associated with the SP SRS AS with CG type 1 PUSCH), or may indicate a TDRA field in the activation DCI (when performing power headroom reporting associated with the SP SRS AS with CG type 2 PUSCH). In addition, when the base station sets timeDomainOffset for the terminal or indicates a TDRA field in the DCI, the base station may need to set timeDomainOffset or indicate a TDRA field in the DCI so that power headroom reporting is performed a predetermined time (e.g., Offset1) after transmitting the SP SRS AS, but within another predetermined time (e.g., Offset2 having a value greater than Offset1).The above-described operation of the base station may be to quickly perform DL precoding by having the base station receive the SP SRS AS and the power headroom report and perform channel estimation and channel estimation correction. If the SP SRS AS is received by the base station and the power headroom report including power imbalance information is performed late, the base station may not be able to quickly correct the UL channel (or DL ​​channel) estimated through the SP SRS AS, which may reduce the effectiveness of the technique.

[0279] Alternatively, if an SP SRS AS is activated and transmitted and a power headroom report associated with the SP SRS AS is triggered, the UE may complete transmission of all SRS resources within the SP SRS AS and transmit a MAC CE for power headroom report to the base station using the fastest scheduled PUSCH (for example, any PUSCH among DCI-based DG PUSCH or RRC-based CG PUSCH can be used) after a certain period of time. At this time, the period of time can be notified by the UE to the base station through the UE capability report as described above, and the base station can set a certain RRC parameter or schedule the PUSCH considering the period of time reported through the UE capability. Alternatively, the base station and the UE may recognize in advance that a certain specific time can be defined in advance to transmit an SRS AS and that a power headroom report can be transmitted through the PUSCH after the certain time.

[0280] PUSCH scheduling method 3) If a Periodic (P) SRS AS is configured by RRC to transmit at a configured periodicity and a power headroom report associated with the P SRS AS is triggered, the base station may configure RRC parameters of a Configured grant (CG) type 1 PUSCH for transmitting the corresponding power headroom MAC CE. In addition, the UE may report the power headroom for the P SRS AS with the configured CG type 1 PUSCH. The base station may configure RRC parameters (e.g., periodicity in ConfiguredGrantConfig and periodicityAndOffset-p in SRS-Resource) for the UE so that the CG type 1 PUSCH, in which the power headroom for the P SRS AS is transmitted, can be transmitted at the same period as the associated P SRS AS. The base station may configure timeDomainOffset so that the CG type 1 PUSCH, in which the power headroom for the P SRS AS is transmitted, can be transmitted a certain time after the time at which the UE transmits all SRS resources in the P SRS AS. In addition, when the base station sets timeDomainOffset to the terminal, the base station may need to set timeDomainOffset so that power headroom reporting is performed a certain time (e.g., Offset1) after transmitting the P SRS AS, but within another certain time (e.g., Offset2 having a value greater than Offset1). The above-described operation of the base station may be such that the base station receives the P SRS AS and receives the power headroom report to perform channel estimation and channel estimation correction to quickly perform DL precoding.If the P SRS AS is received by the base station and the power headroom report including the power imbalance information is performed late, the effectiveness of the technique may be reduced because the base station cannot quickly correct the UL channel (or DL ​​channel) estimated through the P SRS AS.

[0281] Alternatively, if a P SRS AS is activated and transmitted and a power headroom report associated with the P SRS AS is triggered, the UE may complete transmission of all SRS resources within the P SRS AS and transmit a MAC CE for power headroom report to the base station using the fastest scheduled PUSCH (for example, any PUSCH among DCI-based DG PUSCH or RRC-based CG PUSCH may be used) after a certain period of time. At this time, the period of time may be notified by the UE to the base station through the UE capability report as described above, and the base station may configure a certain RRC parameter or schedule the PUSCH considering the period of time reported through the UE capability. Alternatively, the base station and the UE may recognize that a certain specific time may be defined in advance to transmit the SRS AS and that a power headroom report may be transmitted through the PUSCH after the certain time.

[0282] If a power headroom report is triggered according to a trigger condition of a power headroom report associated with the above-described SRS AS, the UE may transmit a PUSCH including a MAC CE for reporting the power headroom to the base station. However, if the power headroom report is not triggered, the UE may not transmit the PUSCH for the purpose of transmitting the MAC CE for reporting the power headroom. For example, an AP SRS AS is scheduled according to the PUSCH scheduling method 1, and the UE may transmit the AP SRS AS. If the AP SRS AS transmitted by the UE does not satisfy the conditions for triggering the power headroom report and / or the conditions for triggering the power headroom report, and thus does not trigger the power headroom report, and there is no UL-SCH for the UE to transmit to the base station, the UE may not transmit the PUSCH to the base station.

[0283] [Terminal / Base Station]

[0284] FIG. 19 is a diagram illustrating the structure of a terminal in a wireless communication system according to an embodiment of the present disclosure.

[0285] Referring to FIG. 19, the terminal may include a transceiver, which refers to a terminal receiving unit (1900) and a terminal transmitting unit (1910), a memory (not shown), and a terminal processing unit (1905, or a terminal control unit or processor). Depending on the communication method of the terminal described above, the transceiver units (1900, 1910), the memory, and the terminal processing unit (1905) 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 or fewer components than the components described above. In addition, the transceiver units (1900, 1910), the memory, and the processor (1905) may be implemented in the form of a single chip.

[0286] The transceiver (1900, 1910) can transmit and receive signals with a base station. Here, the signals may include control information and data. To this end, the transceiver (1900, 1910) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts the frequency of a received signal. However, this is only one embodiment of the transceiver, and the components of the transceiver are not limited to the RF transmitter and RF receiver.

[0287] Additionally, the transceiver (1900, 1910) can receive a signal through a wireless channel and output it to the processor (1905), and transmit a signal output from the processor (1905) through the wireless channel.

[0288] Memory can store programs and data necessary for the terminal's operation. Furthermore, memory can store control information or data included in signals transmitted and received by the terminal. Memory can be comprised of a storage medium, such as ROM, RAM, a hard disk, CD-ROM, or DVD, or a combination of such storage media. Furthermore, there can be multiple memories.

[0289] Additionally, the processor (1905) may control a series of processes to enable the terminal to operate according to the aforementioned embodiments. For example, the processor (1905) may receive a DCI composed of two layers and control components of the terminal to simultaneously receive multiple PDSCHs. There may be multiple processors, and the processor (1905) may perform component control operations of the terminal by executing a program stored in memory.

[0290] FIG. 20 is a diagram illustrating the structure of a base station in a wireless communication system according to an embodiment of the present disclosure.

[0291] Referring to FIG. 20, the base station may include a transceiver, which refers to a base station receiver (2000) and a base station transmitter (2010), a memory (not shown), and a base station processor (2005, or a base station control unit or processor). Depending on the communication method of the base station described above, the transceiver (2000, 2010), the memory, and the base station processor (2005) 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 or fewer components than the components described above. In addition, the transceiver (2000, 2010), the memory, and the processor may be implemented in the form of a single chip.

[0292] The transceiver (2000, 2010) can transmit and receive signals with the terminal. Here, the signals can include control information and data. To this end, the transceiver (2000, 2010) can be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts a received signal. However, this is only one embodiment of the transceiver (2000, 2010), and the components of the transceiver are not limited to the RF transmitter and RF receiver.

[0293] Additionally, the transceiver (2000, 2010) can receive a signal through a wireless channel and output it to the processor (2005), and transmit the signal output from the processor (2005) through the wireless channel.

[0294] The memory can store programs and data necessary for the operation of the base station. Furthermore, the memory can store control information or data included in signals transmitted and received by the base station. The memory can be comprised of a storage medium, such as ROM, RAM, a hard disk, CD-ROM, or DVD, or a combination of such storage media. Furthermore, there can be multiple memories.

[0295] The processor (2005) may control a series of processes so that the base station can operate according to the embodiments of the present disclosure described above. For example, the processor (2005) may configure two layers of DCIs containing allocation information for multiple PDSCHs and control each component of the base station to transmit the same. There may be multiple processors (2005), and the processors may perform component control operations of the base station by executing programs stored in memory.

[0296] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0297] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present disclosure.

[0298] These programs (software modules, software) may be stored in a non-volatile memory including random access memory, flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0299] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a 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 via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

[0300] In the specific embodiments of the present disclosure described above, components included in the invention are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0301] Meanwhile, the embodiments of the present disclosure disclosed in this specification and drawings are only specific examples to easily explain the technical contents of the present disclosure and help understand the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of ​​the present disclosure are possible. In addition, the above-mentioned embodiments can be combined and operated with each other as needed. For example, parts of one embodiment of the present disclosure and parts of another embodiment can be combined with each other to operate a base station and a terminal. For example, parts of the first embodiment and the second embodiment of the present disclosure can be combined with each other to operate a base station and a terminal. In addition, although the above-mentioned embodiments have been presented based on an FDD LTE system, other modifications based on the technical idea of ​​the above-mentioned embodiments can be implemented with other systems such as a TDD LTE system, 5G, or NR system.

[0302] Meanwhile, the order of description in the drawings explaining the method of the present invention does not necessarily correspond to the order of execution, and the order of precedence may be changed or executed in parallel.

[0303] Alternatively, the drawings illustrating the method of the present invention may omit some components and include only some components within a scope that does not harm the essence of the present invention.

[0304] 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 harm the essence of the invention.

[0305] Various embodiments of the present disclosure have been described above. The foregoing description of the present disclosure is for illustrative purposes only, and the embodiments of the present disclosure are not limited to the disclosed embodiments. Those skilled in the art will appreciate that the present disclosure can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present disclosure. The scope of the present disclosure is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present disclosure.

Claims

1. In a method performed by a terminal of a wireless communication system, A step of receiving configuration information regarding SRS (sounding reference signal) resources from a base station; A step of transmitting SRS to the base station based on the setting information; and A method comprising the step of transmitting a power headroom report (PHR) including information about the transmission power of the SRS resources associated with antenna switching to the base station.

2. In paragraph 1, A method wherein the transmission of the PHR is based on at least one of the scheduling type of the SRS, a timer for transmission of the PHR, power comparison information based on the transmission power value of the SRS at the time of calculating the power headroom for the previously transmitted SRS and the transmission power value at the time of transmitting the SRS, or whether or not the SRSs are transmitted for all antennas.

3. In paragraph 1, A method wherein information about the transmission power of the above SRS resources includes information about a power imbalance that occurs when transmitting the SRS on the above SRS resources.

4. In paragraph 3, A method wherein a medium access control (MAC) CE (control element) for transmitting the PHR includes at least one field including information regarding the power imbalance.

5. In a method performed by a base station of a wireless communication system, A step of transmitting configuration information regarding SRS (sounding reference signal) resources to a terminal; A step of receiving SRS from the terminal based on the setting information; and A method comprising the step of receiving, from the terminal, a power headroom report (PHR) including information on transmission power of the SRS resources associated with antenna switching.

6. In paragraph 5, A method wherein reception of the PHR is based on at least one of a scheduling type of the SRS, a timer for transmission of the PHR, power comparison information based on a transmission power value of the SRS at the time of calculating power headroom for a previously transmitted SRS and a transmission power value at the time of transmitting the SRS, or whether SRSs are transmitted for all antennas.

7. In paragraph 5, A method wherein information about the transmission power of the above SRS resources includes information about a power imbalance that occurs when transmitting the SRS on the above SRS resources.

8. In paragraph 7, A method wherein a medium access control (MAC) CE (control element) for transmitting the PHR includes at least one field including information regarding the power imbalance.

9. At the terminal: At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor, so that the terminal: Receive configuration information about SRS (sounding reference signal) resources from the base station, To the above base station, transmit SRS based on the above setting information, and A terminal configured to transmit a power headroom report (PHR) including information about the transmission power of the SRS resources associated with antenna switching to the base station.

10. In paragraph 9, A terminal wherein transmission of the PHR is based on at least one of: a scheduling type of the SRS, a timer for transmission of the PHR, power comparison information based on a transmission power value of the SRS at the time of calculating power headroom for a previously transmitted SRS and a transmission power value at the time of transmitting the SRS, or whether SRSs are transmitted for all antennas.

11. In paragraph 9, A terminal, wherein information about the transmission power of the above SRS resources includes information about a power imbalance that occurs when transmitting the SRS on the above SRS resources.

12. In paragraph 11, A terminal, wherein a MAC (medium access control) CE (control element) for transmitting the PHR includes at least one field including information regarding the power imbalance.

13. At the base station: At least one transceiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions, The above instructions are executed individually or in any combination by the at least one processor so that the base station: Transmits configuration information about SRS (sounding reference signal) resources to the terminal, Receive SRS from the terminal based on the setting information, and A base station configured to receive, from the terminal, a power headroom report (PHR) including information on transmission power of the SRS resources associated with antenna switching.

14. In paragraph 13, A base station, wherein reception of the PHR is based on at least one of: a scheduling type of the SRS, a timer for transmission of the PHR, power comparison information based on a transmission power value of the SRS at the time of calculating power headroom for a previously transmitted SRS and a transmission power value at the time of transmitting the SRS, or whether SRSs are transmitted for all antennas.

15. In paragraph 13, Information about the transmission power of the above SRS resources includes information about power imbalance that occurs when transmitting the SRS on the above SRS resources, and A base station, wherein a MAC (medium access control) CE (control element) for transmitting the PHR includes at least one field including information regarding the power imbalance.

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